JP2001272875A - Fixing device and image forming apparatus to which fixing device is attached - Google Patents

Abstract

PROBLEM TO BE SOLVED: To optimize the coating weight of silicone oil impregnating a web. SOLUTION: The coating mass λ (mg/sheet) of the silicone oil used for recording for one sheet 2, thickness t1 (μm) of the web 4, impregnation rate k1 (mg/mm3) of the silicone oil in the whole thickness of the web, thickness t0 (μm) of the web not impregnated with the silicone oil, thickness t1' (μm) impregnated with a silicone oil release agent, impregnation rate k1' (mg/mm3) of the silicone oil which impregnate this part, residual impregnation rate k2 (mg/mm3) after applying the silicone oil, width B (mm) of the web 4, feeding length V (mm/sheet) of the web per one sheet 2 are controlled to satisfy the relation of λ=(k1'×(1-t0/t1)-k2)×t1×B×V/1000.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a fixing device such as a laser printer and an image forming apparatus to which the fixing device is attached.

[0002]

2. Description of the Related Art A conventional fixing device of an electrophotographic image forming apparatus employs a technique of applying a release agent such as silicone oil to a fixing roller to prevent the toner from being offset to the fixing roller. Have been.

In particular, in a full-color image forming apparatus which performs printing by mixing a plurality of different color toners, the fixing roller needs a very high releasability, so that a large amount of release agent is applied to the fixing roller. You.

Next, a fixing device mounted on a conventional full-color image forming apparatus will be described.

A fixing device for fixing a toner image on paper is
A fixing roller, a pressing roller that rotates while nipping the conveyed unfixed toner image-transferred paper together with the fixing roller, and applying a silicone oil as a release agent to the fixing roller and fixing the toner image after the fixing operation is completed. A web unit having a built-in web for cleaning the surface of the roller and detachably attached thereto.

[0006] The web is stretched around a web roller around which an unused portion is wound and a winding roller which winds up a used portion. Then, the pressing roller is pressed against the front surface of the fixing roller from the back side.

[0007] Such a web is fed through a plurality of gears so as to be taken up by a take-up roller which is driven to rotate by an independent drive source, pressed against the fixing roller by a pressing roller, and offset by the fixing roller. The prevention layer is coated with silicone oil.

Next, the operation of the conventional fixing device configured as described above will be described.

In a state where the fixing roller and the pressure roller are rotated in directions opposite to each other, the toner image is formed by moving in the transport direction while nipping a sheet carrying a plurality of toner images composed of toners of a plurality of colors. The image is heat-fixed while being mixed on paper to form a full-color image on paper.

At this time, the web is sent out by a fixed amount from a web roller rotating in synchronization with the rotation of the fixing roller, and is wound by a winding roller. As a result, the web is coated with a fixed amount of silicone oil on the fixing roller, and the toner adhered to the fixing roller is removed from the sheet to clean the surface of the fixing roller.

[0011]

However, according to the above-mentioned prior art, when the amount of the silicone oil impregnated in the web is too large, excess silicone oil is supplied to the fixing roller, and the recording medium has a streak of the silicone oil. A phenomenon called oil streaks occurs.

If the amount of the silicone oil impregnated in the web is too small, the toner on the recording medium is melted and adheres to the fixing roller, and in the worst case, the recording medium is wound around the fixing roller. A phenomenon called wrapping jam occurs.

To prevent these phenomena, it is necessary to apply an appropriate amount of silicone oil to the fixing roller. However, the amount of silicone oil applied to the fixing roller depends on the type of silicone oil, the material of the web, Because it changes depending on the speed and the amount of silicone oil impregnated into the web,
In order to determine the optimum conditions, it is necessary to repeat trial and error, and it takes time, and the design efficiency of the apparatus is significantly reduced.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a fixing device capable of easily and optimally adjusting the applied mass of a release agent impregnated in a web, and an image forming apparatus to which the fixing device is attached.

[0015]

In order to solve this problem, a fixing device according to the present invention is arranged so as to be in pressure contact with each other, and heats and presses a toner image transferred to a recording medium to apply the toner image to the recording medium. A fixing roller and a pressure roller for fixing, a sheet-like web impregnated with a release agent and pressed by a pressing roller to supply the release agent to the surface of the fixing roller, and a web roller around which an unused portion of the web is wound And a take-up roller that takes up the web after the release agent is supplied to the fixing roller. The application mass of the release agent used when fixing one recording medium is λ (mg / sheet), and the thickness of the web is T
1 (μm), the release agent impregnation rate in the total thickness of the web is k1 (m
g / mm ³ ) and the residual impregnation rate after application of the release agent is k2 (mg
/ Mm ³ ), the width of the web is B (mm), and the web feed amount per sheet when fixing the recording medium is V (mm / sheet), λ = (k1−k2) × t1 × B × V / 1000 Further, the thickness of the portion of the web impregnated with the release agent is represented by t
1 ′ (μm), the thickness of the part not impregnated with the release agent is t0
(Μm) and the impregnation rate of the release agent impregnated in this part is k1 ′ (mg / mm ³ ), the above equation is obtained from the following equation: k1 × t1 = k1 ′ × t1 ′, t1 ′ = t1−t0 , K1 = k1 ′ × (t1-t0) / t1 = k1 ′ ×
(1−t0 / t1), and λ = (k1 ′ × (1−t0 / t1) −k2) × t1 × B
It is adjusted so that the relationship of × V / 1000 is established.

This makes it possible to easily and optimally adjust the applied mass of the release agent impregnated in the web.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is directed to a fixing roller which is disposed in pressure contact with each other, heats and presses a toner image transferred to a recording medium, and fixes the toner image on the recording medium. A pressure roller, a sheet-like web impregnated with a release agent and pressed by a pressing roller to supply the release agent to the surface of the fixing roller, a web roller around which an unused portion of the web is wound, and a release agent. And a take-up roller for taking up the web after being supplied to the fixing roller, wherein the applied mass of the release agent used when fixing one recording medium is λ.
(Mg / sheet), the thickness of the web is t1 (μm), the release agent impregnation rate in the total thickness of the web is k1 (mg / mm ³ ), and the thickness of the portion of the web impregnated with the release agent is t1 ′ (Μ
m), the thickness of the portion not impregnated with the release agent is t0 (μm)
And the impregnation rate of the release agent impregnated in this portion is k
1 ′ (mg / mm ³ ), the residual impregnation rate after application of the release agent is k2 (mg / mm ³ ), the web width is B (mm),
V (mm / mm)
) = (K1-k2) × t1 × B × V / 1000: k1 × t1 = k1 ′ × t1 ′, t1 ′ = t1−t0 From the equation, k1 = k1 '× (t1-t0) / t1 = k1' × (1-
t0 / t1), and λ = (k1 ′ × (1−t0 / t1) −k2) × t1 × B
The fixing device is adjusted so as to satisfy the relationship of × V / 1000, and has an effect that the applied mass of the release agent used at the time of fixing can be easily and optimally adjusted.

According to a second aspect of the present invention, in the first aspect of the invention, when the release agent is silicone oil, the applied mass λ (mg / sheet) of the release agent is 1.0 to 4.0.
(Mg / sheet), and has the effect that it is possible to easily and optimally adjust the applied mass of the release agent impregnated in the web.

According to a third aspect of the present invention, in the first or second aspect, when the web is a nonwoven fabric, the release agent impregnation rate k (mg / mm ³ ) of the web is 0.15 to 0.15. At 0.50 (mg / mm ³ ), the thickness t0 (μm) of the portion of the web not impregnated with the release agent is t0 = 2.
The fixing device is set to 0 to 40 (μm), and has an effect that the applied mass of the release agent impregnated in the web can be easily and optimally adjusted.

According to a fourth aspect of the present invention, there is provided an image forming apparatus to which the fixing device according to any one of the first to third aspects is attached, wherein the mass of the release agent impregnated in the web is applied. Can be easily and optimally adjusted.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG.

FIG. 1 is a conceptual diagram showing a fixing device according to an embodiment of the present invention, FIG. 2 is a conceptual diagram of impregnation of a web with a release agent,
FIG. 3 is a conceptual diagram in which a web is sandwiched between a pressing roller and a fixing roller, and a release agent is applied to the fixing roller. FIG. 4 shows the relationship between the thickness of the web and the amount of silicone oil impregnated in the fixing device of FIG. It is a graph.

The fixing device according to the embodiment of the present invention is used by being attached to an image forming apparatus such as a full-color image forming apparatus.

Here, in the full-color image forming apparatus, black (B), cyan (C), magenta (M), yellow ( A developing device for storing the toner of each color Y), a charging device for charging the photoreceptor belt by corona discharge, and the like are provided. In addition, a semiconductor laser element is built in, and a laser beam is applied to the photoreceptor belt while switching between laser emission and extinguishment in accordance with image data to form an electrostatic latent image (LSU).
t) is provided. Further, an intermediate transfer belt on which the toner image on the photoconductor belt is transferred is provided opposite to the photoconductor belt.

A paper transport path is formed so as to come into contact with the rotating intermediate transfer belt, and the toner image formed on the intermediate transfer belt is transferred to a paper transported on the paper transport path. You.

A fixing device shown in FIG. 1 is installed on the downstream side of the sheet conveying path, and the unfixed toner image transferred to the sheet is heated and pressed and fixed by the fixing device.

Here, as shown in FIG. 1, the fixing device for fixing the toner image on the paper (recording medium) 2 has an optimum fixing temperature (160.degree.
180 ° C.)
A pressure roller 3 which is disposed in pressure contact with the fixing roller 1 and rotates while nipping the sheet 2 on which the unfixed toner image transferred has been transferred together with the fixing roller 1; A web unit having a built-in sheet-like web 4 serving as a release agent applying means for applying oil and cleaning the surface of the fixing roller 1 having completed the fixing operation, and which is detachably attached upward (in the direction indicated by arrow A). Five.

In the present invention, a release agent other than silicone oil can be used.

The web 4 incorporated in the web unit 5 is made of, for example, a nonwoven fabric, and is impregnated with a release agent such as silicone oil having a viscosity of 500 cS. Such a web 4 is stretched on a web roller 6 around which an unused portion is wound and a take-up roller 7 which applies a release agent to the surface of the fixing roller 1 and winds up a used portion whose surface has been cleaned. It is suspended.

The web 4 is pressed against the front surface of the fixing roller 1 by the pressing roller 8 from the back side.

Here, the fixing roller 1 has an elastic layer made of a high-temperature vulcanized silicone rubber (hereinafter, referred to as "HTV silicone rubber") formed on an aluminum core (not shown) as a base material. An oil-resistant layer made of fluoro rubber is formed on the elastic layer, and an anti-offset layer made of room temperature vulcanized silicone rubber (hereinafter, referred to as "RTV silicone rubber") is formed thereon. The outer diameter of the fixing roller 1 is, for example, φ40 mm.

The pressure roller 3 is formed by forming an elastic layer made of HTV silicone rubber on an aluminum core (not shown) and forming a resin layer of a fluororesin on the elastic layer. The outer diameter is, for example, φ as in the fixing roller 1.
40 mm.

A halogen heater (not shown) is arranged in the core of the fixing roller 1 and in the core of the pressure roller 3, respectively. Then, the temperature of the fixing roller 1 is detected by a thermistor (not shown) in contact with the fixing roller 1, and the halogen heater is turned on / off to maintain the temperature of the fixing roller 1 at about 165 ° C.

The fixing roller 1 and the pressure roller 3, which are fixing means, are continuously rotated during a printing operation by a driving mechanism (not shown).

On the other hand, the web 4 may be fed intermittently as required, and its transport (winding) speed may be lower than the rotation speed of the fixing roller 1. Therefore, the web 4 is fed through the gears 9, 10, 11 so as to be taken up by the take-up roller 7, which is rotationally driven by an independent drive source (motor), and pressed against the fixing roller 1 by the pressing roller 8. Then, silicone oil is applied to the offset prevention layer of the fixing roller 1. The take-up roller 7 has a one-way clutch (not shown).
And is configured to rotate only in the direction in which the web 4 is wound.

Next, the operation of the fixing device configured as described above will be described.

The fixing roller 1 and the pressing roller 3 rotate in opposite directions, in the illustrated case, the fixing roller 1 rotates in a counterclockwise direction indicated by an arrow B, and the pressing roller 3 rotates in a clockwise direction indicated by an arrow C. . Then, the toner image composed of toners of a plurality of colors is moved in the transport direction shown by the arrow D while sandwiching the sheet 2 carrying the toner image thereon, so that the toner image is heat-fixed while being mixed on the sheet 2 and full-colored. An image is formed on paper 2.

At this time, the web 4 is sent out from the web roller 6 which rotates in the counterclockwise direction indicated by the arrow E in synchronism with the rotation of the fixing roller 1, and is taken up by the take-up roller 7.

As a result, the web 4 applies a fixed amount of silicone oil to the fixing roller 1 at a time, and removes toner adhered to the fixing roller 1 from the paper 2 to clean the surface of the fixing roller 1.

Silicone oil application rate λ (mg / sheet)
Is determined by, for example, printing a certain number of sheets, measuring the mass before and after the printing, and dividing the difference in the mass by the number of printed sheets, and is described below in terms of the mass of silicone oil contained in the entire web.

In such a fixing device, the total mass of the silicone oil impregnated in the web 4 is represented by Ot (m
g), assuming that the remaining amount of silicone oil in the web 4 after use is Or (mg), the usage amount Om (mg) of the silicone oil actually used for fixing is: Om = Ot-Or ... ( Equation 1) is obtained.

Accordingly, the amount of silicone oil used O
m is determined by measuring the mass of the web 4 before and after use.

Next, the number of sheets 2 in the entire web is represented by P
(Sheets), the applied mass λ (mg / sheet) of the silicone oil used for recording one sheet of paper 2 is obtained by λ = Om / P (Equation 2).

Assuming that the feed amount of the web 4 when recording one sheet 2 is V (mm / sheet) and the total length of the web 4 is L (mm), P = L / V (Equation 3) Therefore, silicone oil application mass λ (mg /
Λ = Om / (L / V) = Om × V / L (Equation 4)

Here, the impregnation mass of the silicone oil is one.
Generally proportional to the effective thickness t1 '(μm) of the web
And the thickness of the web 4 is t1 (μm),
The thickness of the portion not impregnated with the silicone oil of No. 4 is t0
(Μm), the release agent impregnation rate is k1 (mg / mm^Three)
And the silicone oil impregnation rate ω1 (m
g / mm^Two) Is ω1 = k1 × t1 / 1000 = k1 ′ × t1 ′ / 1000 (Equation 5) t1 ′ = t1−t0, and also includes silicone oil per web area after use.
Immersion rate ω2 (mg / mm ^Two) Indicates the release agent impregnation rate after use.
k2 (mg / mm^Three), Ω2 = k2 × t1 / 1000.

Accordingly, if the width of the web 4 is B (mm), the amount of silicone oil used O in the entire web 4
m (mg) is as follows: Om = (ω1−ω2) × B × L (Equation 6)

By substituting (Equation 5) into (Equation 6), Om = (k1 × t1−k2 × t1) × B × L / 1000 = (k1 ′ × t1′−k2 × t1) × B × L / 1000 = k1 ′ × (t1−t0) −K2 × t1) × B × L / 1000 (Equation 7)

Then, when (Equation 7) is substituted into (Equation 4), the silicone oil application mass λ (mg / sheet) is as follows: λ = (k1 ′ × (t1−t0) −k2 × t1) × B × L / 1000 × V / L = (k1 ′ × (t1−t0) −k2 × t1) × B × V / 1000 (Equation 8)

Here, the release agent impregnation rates k1 (mg / mm ³ ) and k1 ′ (mg / m ³ ) of the web where no release agent leakage occurs.
m ³ ) and the thickness t0 (μm) at which the silicone oil in the web 4 is not impregnated are determined by the type of the web 4.

The width B (mm) of the web 4 is determined by the paper size that can be handled by the fixing device, and the required coating mass λ (mg / sheet) of the silicone oil depends on the type of the release agent such as the silicone oil and the printing. Depends on the type of toner used.

An experiment was conducted under the conditions shown in the following (Table 1) by using, for example, a nonwoven fabric of Gore-Tex manufactured by Gore as the web 4. As a result, the maximum release agent impregnation of the web was found from (Equation 7). The rate is k1 = 0.15 to 0.50 (mg / mm
³ ), k1 ′ = 0.45 to 0.55 (mg / mm ³ ), thickness t0 of the web 4 where the silicone oil is not impregnated
20 to 40 (μm) was determined.

It should be noted that a non-woven fabric other than the above-mentioned products can be used.

[0053]

[Table 1]

When the experiment is further repeated, as shown in FIG. 4, there is a risk that in the area a, the amount of the silicone oil is too large to cause oil streaks, and in the area b, the amount of the silicone oil is too small to cause an offset. Was found to be high.

Therefore, the silicone oil impregnation rate k1 'of the web not including this region is 0.45 to 0.5.
55 (mg / sheet), it was found that the thickness t0 of the portion of the web that was not impregnated with the silicone oil should be set to 20 to 40 (μm).

As a result of an experiment conducted by using silicone oil as a release agent, as shown in the following (Table 2), the applied mass λ of the silicone oil was 1.0 to 4.0.
(Mg / sheet), it was found that no oil streaks on the sheet 2 and no offset of the sheet 2 to the fixing roller 1 occurred, and good recording could be performed.

[0057]

[Table 2]

As described above, by adjusting so as to satisfy the above numerical conditions, it is possible to easily and optimally adjust the applied mass of the release agent such as silicone oil impregnated in the web.

[0059]

As described above, according to the present invention, there is obtained an effective effect that it is possible to easily and optimally adjust the applied mass of the release agent impregnated in the web.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a fixing device according to an embodiment of the present invention;

FIG. 2 is a conceptual diagram of web impregnation with a release agent.

FIG. 3 shows a state in which a web is sandwiched between a pressing roller and a fixing roller,
Conceptual diagram of applying release agent to fixing roller

4 is a graph showing the relationship between the thickness of the web and the amount of silicone oil impregnated in the fixing device of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixing roller 2 Paper (recording medium) 3 Pressure roller 4 Web 6 Web roller 7 Take-up roller 8 Press roller

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Tetsuya Koyasu 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Inventor Junichi Terayama 1006 Kazuma Kadoma, Kazuma, Osaka Prefecture F-term in Matsushita Electric Industrial Co., Ltd. (reference) 2H033 AA09 BA46 BA51 BA55 BB01 BB28

Claims (4)

[Claims] 1. A fixing roller and a pressure roller, which are arranged in pressure contact with each other, heat and pressurize a toner image transferred to a recording medium, and fix the toner image on the recording medium, and a pressing roller impregnated with a release agent. A sheet-like web that is pressed to supply the release agent to the surface of the fixing roller; a web roller around which an unused portion of the web is wound; and the web after the release agent is supplied to the fixing roller. And a take-up roller for taking up the release agent used to record one sheet of the recording medium, the applied mass of the release agent is λ (mg / sheet), and the total thickness of the web is t1 (μ
m), the web impregnation rate of the release agent before use is k1 (mg / mg
mm ³ ), the width of the web is B (mm), the web feed amount when recording one recording medium is V (mm / sheet), and the release agent impregnation rate after use is k2 (mg / mm ³ ). , Λ = (k1−k2) × t1 × B × V / 1000 The fixing device is adjusted to satisfy the following relationship. 2. The fixing device according to claim 1, wherein when the release agent is silicone oil, the applied mass λ (mg / sheet) of the release agent is set to 1.0 to 4.0. . 3. The release agent impregnation rate k1 (mg / mm ³ ) for impregnating the entire thickness of the web in the web is 0.15 to 0.5.
0, when the thickness of the web surface layer in which the release agent in the web is not effectively impregnated is t0 (μm), t0 = 20 to
40 (μm), the effective thickness for impregnating the web with the release agent is t1 ′ (mm), and the impregnation rate of the release agent contained in the effective thickness is k1 ′ (mg / mm ^3). ), T1 ′ = t1−t0 k1 × t1 = k1 ′ × t1 ′, and the maximum release agent within the effective thickness of the release agent which does not cause the release agent to spill from the web in use and storage conditions. The impregnation rate k1 ′ (mg / mm ³ ) is 0.45 to 0.55, and the release agent impregnation rate k2 (mg / mm ³ ) after use is 0.05.
The fixing device according to claim 1, wherein the fixing device has a value of −0.10. 4. An image forming apparatus to which the fixing device according to claim 1 is attached.