JP3207749B2 - Fixing roller - 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 roller (heating fixing roller) constituting a fixing device provided in an image forming apparatus such as a copying machine, a facsimile, and a printer.

[0002]

2. Description of the Related Art FIG. 6 is a schematic explanatory view showing an example of a conventional copying machine. In this figure, 21 is a copying machine main body, 22 is a cover, 23 is a paper feeding unit, 23a is a recording sheet, 24 is a photosensitive member having a photosensitive layer 24a on its surface, 25 is a transfer device,
5a is a conveying roller, 25b is an endless belt, 26 is a fixing device, and 30 is an auxiliary roller. The fixing device 26 includes a pressure roller 27 and a fixing roller 28. Fixing roller 2
8 contacts the pressure roller 27 and rotates following the rotation of the pressure roller 27 to form a nip portion 29. The fixing roller 28 includes a cylindrical cored bar 28a made of aluminum or the like and having a built-in heater (not shown) such as a halogen lamp.
And a protective layer 28b provided on the outer peripheral surface of the cored bar 28a for preventing toner from sticking, such as a fluororesin. The pressure roller 27 has an elastic body 27 such as rubber on the outer peripheral surface of a metal core 27a made of a metal material such as aluminum.
b.

In the above copying machine, a recording sheet 23a set in a sheet feeding section 23 is fed to a photoconductor 24 at a predetermined timing. The toner image formed on the photoreceptor 24 is transferred to a recording sheet 23 a by a transfer device 25, and the recording sheet 23 a
9, where the recording sheet 23a is fixed to the fixing roller 28.
The toner image is fixed by being heated by the outer peripheral surface of the toner image.

However, in the above fixing device, the fixing roller 2
A relatively long warm-up time was required from when power was supplied to the heater No. 8 to when the outer peripheral surface of the fixing roller 28 reached a temperature required for fixing. In order to solve this problem, a method of preheating the fixing roller 28 when the main power is turned on has been generally adopted. However, this method has a new problem that power is wasted.

Japanese Patent Application Laid-Open No. 7-140823 discloses a fixing roller capable of shortening a warm-up time. This fixing roller is intended to solve the above problem. For example, as shown in FIGS. 7 and 8, in a fixing roller for electrophotographic fixing having a cored bar 31 having a built-in heater (not shown), In the middle between the metal core 31 and the protective layer 33, the 3B group to 6 group of the periodic table (long period type)
A heating layer 32 made of an amorphous material selected from one or more elements belonging to Group B is provided.

The above-mentioned amorphous material is a material capable of undergoing a phase transition between crystalline and amorphous, and has a property of releasing crystallization heat when the amorphous is crystallized by heating. That is, an exothermic phase change material. Specific examples of such an amorphous material include selenium and a selenium-tellurium alloy.

In the fixing roller described in the above publication, when the heater generates heat when energized when the fixing device is started,
When the heat generating layer (amorphous material layer) 32 is heated and reaches the crystallization temperature, the crystallization heat is released. For this reason, since the outer peripheral surface of the fixing roller quickly reaches the fixing-possible temperature, the warm-up time can be reduced. Thereafter, the temperature of the outer peripheral surface of the fixing roller is controlled by the heat generated by the heater, and the fixing operation is performed as described above. At the time of fixing, the heat generating layer 32 is maintained in a crystallized state.

After the fixing device is used, a large electric power is temporarily supplied to the heater to heat and crystallize the crystallized heat generating layer 32 to a temperature higher than its melting point, and then turn off the power and rapidly cool. In this case, the liquid heating layer 32 becomes amorphous. If the heating layer 32 in this state is heated again by the heater, the fixing roller can be quickly heated by releasing the heat of crystallization in the same manner.

As described above, the above-mentioned amorphous material undergoes a phase change in accordance with the heating / cooling cycle of “crystallization / heating by heating → liquefaction by heating / melting → amorphization by rapid cooling → crystallization / heating by heating”. Is what you do. Therefore, the fixing roller described in the above publication has a structure in which the liquid amorphous material is sealed by a protective layer also serving as a release layer in order to prevent the liquid amorphous material from leaking to the outside. .

[0010]

However, in the fixing roller having the above structure, there is no problem if the heating temperature is strictly controlled at or near the melting point when the amorphous material is melted.
If the heating temperature is too high, the liquefied amorphous material has a large decrease in viscosity, is fluidized by its own weight inside the protective layer, and collects at the lower portion of the fixing roller. For this reason, the thickness of the amorphous material layer becomes large on the lower side of the fixing roller and becomes thinner on the upper side. As a result, the temperature of the outer peripheral surface of the fixing roller becomes uneven. In the recording sheet, the toner may have a non-fixed state due to the temperature non-uniformity, and may not be fixed. When the pressure in the space sealing the amorphous material is non-uniform, the thickness of the amorphous material layer becomes thinner in a portion where the pressure is high, and becomes amorphous in a portion where the pressure is low. The thickness of the material layer is increased, and the same problem as described above may occur. Further, there is a concern that the fixing roller may be deformed due to uneven temperature.

Therefore, an object of the present invention is to provide a fixing roller having an amorphous material layer, that is, a heating layer for emitting crystal heating, between a cored bar and a protective layer. Even when heating is performed at a temperature considerably higher than the temperature required for melting, or when the pressure in the space sealing the amorphous material is not uniform, a fixing roller that does not cause temperature unevenness on the outer peripheral surface. To provide.

[0012]

The fixing roller according to the present invention comprises:
A dam-shaped convex portion for suppressing the liquefied amorphous material from flowing in the space enclosing the amorphous material is formed by (1) outside the cored bar.
(2) Secured to the inner peripheral surface of the protective layer by the member fixed to the peripheral surface
These are formed by the members described above.

[0013] In the fixing roller according to the first aspect, a heating layer made of a phase change material capable of phase transition between crystalline and amorphous is sealed between the core metal and the protective layer. A fixing roller provided so as to increase the temperature of the outer peripheral surface by heat generated at the time of the phase transition of the phase change material by heating. A plurality of protrusions are provided in the circumferential direction of the gold, and the protrusions on the outer peripheral surface side of the core metal correspond to the outer peripheral surface of the core metal.
Formed of a material fixed to the
Has a thermal conductivity equivalent to that of the crystallized phase change material
It is characterized by that. Claim 2
2. The core roller according to claim 1, wherein the application roller is an outer periphery of the core metal.
In the convex part on the surface side, the shape of the core
The bottom is trapezoidal located on the core metal side, or the base is the core metal
And the vertex angle is an acute triangle, and its height is
It is characterized by being smaller than the thickness of the heat generating layer.

According to a third aspect of the present invention, in the fixing roller, a heat generating layer made of a phase transition material capable of phase transition between crystalline and amorphous is sealed between the core metal and the protective layer. A fixing roller provided so that a temperature rise of an outer peripheral surface is promoted by heat generated at the time of phase transition of the phase change material by heating; A plurality of protrusions are provided in the direction, the protrusion on the inner peripheral surface side of the protective layer is formed of a material fixed to the inner peripheral surface of the protective layer, and the material is formed of a phase change material in a crystallized state. It is characterized by having a thermal conductivity equivalent to the thermal conductivity. Claim 4
The fixing roller according to claim 3, wherein in the convex portion on the inner peripheral surface side of the protective layer, the shape of the core metal in a section perpendicular to the axis is a trapezoid whose lower bottom is located on the protective layer side . ,
Alternatively, it is characterized in that the base is on the side of the protective layer, the vertex is an acute triangle with an acute angle, and the height is smaller than the thickness of the heat generating layer.

[0015]

In the fixing roller according to the first and third aspects, the flow of the liquefied phase change material in the annular space that seals the heat generating layer is suppressed by the convex portions existing in the annular space. Therefore, the above-described conventional problem is solved. In other words, when the fixing roller warms up and the toner is fixed, the heat generating layer (the heat generating layer changes from an amorphous state to a crystalline state in the former case, and is in a crystalline state in the latter case). Although if it is maintained in a uniform thickness over the fixing roller entire conventional problems are solved, after the heat generation layer of the liquid was flowing inside the annular space, uneven thickness of the heating layer of the amorphous state However, when the amorphous state changes to the crystalline state (at the time of warm-up) and also after the crystallization is completed, the thickness of the heat generating layer (at the time of fixing the toner) also becomes uneven. For this reason, the heating temperature of the fixing roller becomes non-uniform at the time of warm-up and at the time of toner fixing, and the above-described conventional problem occurs.

In the first to fourth aspects of the present invention , the phase change substance is a substance having a property of becoming amorphous when the molten state is quenched.
No. 823 can be adopted. Specifically, one selected from one or more elements belonging to groups 3B to 6B of the periodic table, such as chalcogen, chalcogenide compounds, selenium, selenium-tellurium alloy, germanium-tellurium alloy, indium-selenium alloy, indium・ Tellurium alloy, antimony selenium alloy, antimony
Tellurium alloy can be adopted. As the phase transition material, a crystalline thermoplastic polymer having an amorphous region, for example, a polyester resin (PET or the like) can also be used. These phase change materials preferably have a crystallization temperature in the range of 80 to 200 ° C. In addition, selenium or a selenium-tellurium alloy is particularly desirable in view of the fact that the fixing temperature is about 180 ° C. and that it is preferable that heat is generated during crystallization.

As the core metal, a conventionally used metal having a high thermal conductivity, for example, aluminum can be adopted. The protective layer is made of a material (release resin) that can prevent the toner from sticking,
For example, it may be formed only of a fluorine resin, or may be formed by providing a release resin layer on the surface of a base layer made of a metal having high thermal conductivity, for example, aluminum.

According to the first aspect of the present invention, in the fixing roller, the outer peripheral surface of the cored bar is provided.
Is formed of a material fixed to the outer peripheral surface of the cored bar.
As a material, the heat conductivity and heat capacity were equivalent to those of the phase change material in the crystallized state, and the heat conductivity and heat capacity of the projections were defined as described above. The entire outer peripheral surface of the fixing roller can be more uniformly heated by the heater. If the thermal conductivity or heat capacity is significantly different from those of the crystallized phase change material, deformation or protrusion may occur on the protective layer (and thus on the outer peripheral surface of the fixing roller ).

[0020] Also, unlike the phase transition material, the above-mentioned protruding portion is made of a metal.
In the fixing roller according to claim 1, it is preferable that the width of the convex portion on the outer peripheral surface side of the core metal is as narrow as possible. (1) The shape of the core metal in a cross section perpendicular to the axis is a trapezoid whose lower part is located on the core metal side, or whose bottom is located on the core metal side and whose acute angle is an acute triangle with an acute angle, (2) It is preferable that the height is lower than the thickness of the heat generating layer. In the case of (2), it is desirable that the height of the projection is as close as possible to the thickness of the heating layer.

The above (1) is preferable because, when a convex portion is formed on the outer peripheral surface side of the metal core, the processing becomes easy, and
This is because, in order to quickly heat the outer peripheral surface of the fixing roller due to the heat generated by the phase change material, the smaller the width of the convex portion, the better. The reason (2) is desirable is that the closer the height of the convex portion is to the thickness of the heat generating layer, the higher the flow prevention effect of the liquefied phase change material is. If they match, or if the height of the projection is higher than the thickness of the crystallized phase-change heating layer, the phase-change heating layer does not exist in the projection and immediately above the projection. Since no heat is generated by the crystallization of the fixing roller, the effect of sealing the phase change material becomes insufficient or the fixing roller has uneven temperature.

In the fixing roller according to the third aspect, the convex portion on the inner peripheral surface side of the protective layer is formed of a material fixed to the inner peripheral surface of the protective layer. Since the thermal conductivity and the thermal capacity of the projections are equivalent to those of the phase change material in the state and the thermal conductivity and the thermal capacity of the projections are defined in this manner, the same effect as the fixing roller according to the first aspect is obtained. In the convex portion on the inner peripheral surface side of the protective layer, the shape of the core metal in a cross section perpendicular to the axis is a trapezoid whose lower bottom is located on the protective layer side , or whose apex angle is acute when the bottom is located on the protective layer side. The reason why it is better to make the shape of the acute angle triangle smaller than the thickness of the heat generating layer is also as described above.

In the fixing roller according to any one of claims 1 to 4, when the toner image is fixed on the recording sheet, the crystallized solid heat generating layer rotates integrally with the fixing roller. It is preferable to configure as follows. The reason is that the outer peripheral surface of the fixing roller can be stably and uniformly heated to a predetermined fixing temperature, so that a high-quality image without unevenness can be obtained. .

If the heat generating layer rattles in the annular space between the metal core and the protective layer during rotation of the fixing roller , the heat from the heater incorporated in the metal core is not accurately transferred to the protective layer of the fixing roller , and the fixing is performed. Temperature unevenness may occur on the outer peripheral surface of the roller . To surely prevent the above-mentioned rattling of the heating layer,
It is preferable that the crystallized solid heat generating layer is in a state of cutting into the concave portion formed by the convex portion.

[0025]

Embodiments of the present invention will be described below with reference to the drawings. Example 1 The surface of an outer diameter-ground aluminum core having an outer diameter of 40 mm and a surface roughness Rz of 1 μm or less was rubbed in the axial direction with sandpaper to roughen the surface, and the Rmax was set to 50 μm (convex on the outer peripheral surface of the core) Part). A 100 μm-thick polyethylene terephthalate (PET) sheet curled by preheating at 150 ° C. (trade name: Mylar, manufactured by DuPont)
Is wound around the surface of the core metal, and furthermore, a conductive P
A heat-shrinkable tube made of FA resin (PFA is a perfluoroalkoxyfluoride plastic) was covered.

The roller is set in a heating furnace, and the inside of the furnace is heated to 300 ° C. higher than the melting point of PET and lower than the melting point of PFA while depressurizing the inside of the furnace. A roller was made. This was designated as Sample No. 1
And FIG. 1 shows the cross section of the sample perpendicular to the axis.
FIG. 2 is an enlarged view of a portion A in FIG. 1. That is, the heat generating layer 2 is formed of PET after being melted and solidified (amorphized), and the protective layer 3 also serving as a release layer is formed of a PFA tube. The upper portion of the heat generating layer 2 is in close contact with the inner peripheral surface of the protective layer 3, and the lower portion is in close contact with the uneven surface formed by the convex portions 11 having an acute triangular cross section. In addition, the height of the convex portion 11 is lower than the thickness t of the heating layer 2 in the amorphous state.

Example 2 A heat dispersing agent in which a conductive dispersing agent is dispersed on the surface of an aluminum core bar having an outer diameter of 40 mm and a surface roughness Rz of 1 μm or less and having been finished along an outer diameter thereof and along the axis of the core bar. A plurality of embankments (projections) were formed in the circumferential direction of the core by applying a curable resin adhesive in a thin line shape. A 100 μm-thick PET sheet (same as in Example 1), which was preheated and curled at 150 ° C., was cut into a strip, and the width thereof was slightly smaller than the interval between the protrusions. This band-shaped sheet was inserted into the gap between the projections and attached. This cored bar was covered with a conductive PFA tube (same as in Example 1) and heated under reduced pressure in the same manner as in Example 1 to produce a fixing roller. And 2.

The thermal conductivity of the adhesive is about 10 W / mK, which is equivalent to that of the PET sheet. FIG. 3 is an enlarged view of the cross section perpendicular to the axis of the sample. The heat generating layer 2 is formed by PET after melting and solidification, and the protective layer 3 is formed by the PFA tube. The convex portion on the outer peripheral surface side of the cored bar 1 is formed by the above-mentioned adhesive fixed to the outer peripheral surface of the cored bar. In this sample, convex portions 1 having different shapes are used.
1a and 11b are formed, and the former has a cross-sectional shape of
The lower base is a trapezoidal shape located on the cored bar side, and the latter is an acute triangle having a base located on the cored bar side and an apex angle of an acute angle. The upper portion of the heat generating layer 2 is in close contact with the inner peripheral surface of the protective layer 3, and the lower portion is the convex portion 1.
It is in close contact with the uneven surface of 1a, 11b. In addition, convex part 1
The height of 1 is slightly lower than the thickness t of the heating layer 2 in the amorphous state.

Example 3 A 100 μm-thick PET sheet (cured) was preliminarily heated at 150 ° C. and curled on the surface of an aluminum core bar having an outer diameter of 40 mm and a surface roughness Rz of 1 μm or less. (Same as in Example 1). On top of this, a conductive PFA tube (the material was the same as in Example 1) having irregularities formed on one side was covered with the irregularities facing toward the metal core. Less than,
Heating under reduced pressure was performed in the same manner as in Example 1 to produce a fixing roller. It was set to 3.

FIG. 4 shows the cross-section perpendicular to the axis of this sample.
FIG. 5 is an enlarged view of a portion B in FIG.
It is formed on the inner peripheral surface of the protective layer 3 made of an A tube. The heat generating layer 2 is formed of PET after melting and solidification. The upper portion of the heat generating layer 2 is in close contact with the uneven surface formed by the convex portions 11, and the lower portion is in close contact with the outer peripheral surface of the metal core 1.

Next, a comparative example relating to a conventional fixing roller will be described. Comparative Example 1 A 100 μm-thick PET sheet curled by preheating and curling at 150 ° C. on the surface of an aluminum core bar having an outer diameter of 40 mm and a surface roughness Rz of 1 μm or less and having an outer diameter of 1 μm or less. The same). A normal conductive PFA tube (with the same material as in Example 1) having no irregularities was put thereon. Thereafter, a fixing roller was prepared by heating under reduced pressure in the same manner as in Example 1, and this was used as a sample No. And 4. As shown in FIG. 8, the cross-sectional shape of the sample perpendicular to the axis was such that no protrusion was formed on either the outer peripheral surface of the core metal or the inner peripheral surface of the protective layer.

Sample No. The fixing rollers 1 to 4 are individually incorporated into the fixing device of the electrophotographic copying machine M210 manufactured by Ricoh Co., Ltd.
00W was supplied to generate heat, the protective layer was heated to an abnormally high temperature of about 20 ° C. higher than the normal heating temperature, and the surface condition of the roller (the state of fluidized deformation of the roller heat generating layer due to abnormal temperature rise) was examined. The normal heating conditions of the fixing roller are 960 W during heating and 1100 W during initializing and melting.

As a result, the sample No. 1 (Example 1) to Sample No. 1 In No. 3 (Example 3), no abnormalities such as deformation were observed. On the other hand, the sample No. 4 (Comparative Example 1), when heating while rotating the roller,
Swelling occurred at the bottom of the roller, and dents and wrinkles occurred at the top. When heated without rotating the roller, the swelling of the lower part of the roller and the dents and wrinkles of the upper part were remarkable.

[0034]

As described above, the fixing roller according to claim 1 is used .
Over La, the fixing roller <br/> having a heat generating layer formed of a phase transition material, the outer peripheral surface side of the core, and, since is provided with a plurality of convex portions in a circumferential direction, the fixing In Laura ,
Even if the phase transition material is heated to a considerably higher temperature than the melting temperature due to an unexpected reason, or if the pressure in the annular space in which the phase transition material is sealed becomes uneven, the liquefied phase transition Since there is no flow deformation of the material, the outer peripheral surface of the fixing roller can be uniformly heated , so that the roller is not partially deformed or a projection is generated, and a stable high-quality image is obtained. Can be obtained. Also, the above-mentioned convex portion is formed of a material fixed to the outer peripheral surface of the cored bar.
And, to this material its thermal conductivity, crystal phase transition state
Since the material having the same thermal conductivity as that of the material is used, the entire outer peripheral surface of the fixing roller can be more uniformly heated by the heater built in the metal core at the time of fixing. Claim
In the fixing roller described in No. 2, since the cross-sectional shape of the projection is a trapezoid or an acute triangle , it is determined by the heat generated by the phase change material.
The outer peripheral surface of the forming roller can be made quickly, and the height of the convex
Since the thickness of the heat generating layer is set to be lower than the thickness of the heat generating layer and is made as close as possible to the thickness of the heat generating layer, the effect of preventing the liquefied phase change material from flowing is improved, and the uniformity of the outer peripheral surface temperature of the fixing roller is improved. The fixing roller according to claim 3, further comprising a phase change material.
In the fixing roller provided with the heat generation layer composed of
A plurality of protrusions are provided on the inner peripheral surface side and in the circumferential direction,
The convex portion is formed of a material fixed to the inner peripheral surface side of the protective layer,
This material has a thermal conductivity that is a phase change substance in the crystallized state.
Claim 1 because the same thermal conductivity as that of
The same effect as that of the fixing roller is obtained. Claim 4
The fixing roller has a trapezoidal or acute angle
Square and the height of the protrusion is lower than the thickness of the heat generating layer.
Comb and as close as possible to the thickness of the heating layer,
The same effect as the fixing roller according to the second aspect is obtained. What
The technique of forming a bank-shaped protrusion as in the present invention is based on a low
Means for preventing fluidization of the liquid sealed in
And can be widely applied.

[0035]

[Brief description of the drawings]

FIG. 1 is a cross-sectional view (a cross-section perpendicular to an axis) of a fixing roller according to an embodiment of the present invention.

FIG. 2 is an enlarged view of a portion A in FIG.

FIG. 3 is a cross-sectional view of a fixing roller according to another embodiment, which is partially enlarged.

FIG. 4 is a cross-sectional view of a fixing roller according to still another embodiment.

FIG. 5 is an enlarged view of a portion B in FIG. 4;

FIG. 6 is a schematic explanatory view showing the structure of a conventional copying machine.

FIG. 7 is a longitudinal sectional view showing a conventional example of a fixing roller capable of shortening a warm-up time.

8 is a cross-sectional view of FIG.

[Explanation of symbols]

 1,31 core metal 2,32 heating layer 3,33 protective layer 11,11a, 11b convex part

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-7-140823 (JP, A) JP-A-2-688582 (JP, A) Japanese Utility Model Showa 58-50456 (JP, U) (58) Field (Int.Cl. ⁷ , DB name) G03G 13/20 G03G 15/20 F16C 13/00

Claims (4)

(57) [Claims] 1. A heating layer made of a phase change material capable of phase transition between crystalline and amorphous is provided between a metal core and a protective layer in a sealed manner. In the fixing roller configured to promote the temperature rise of the outer peripheral surface by heat generated at the time of phase transition, a plurality of convex portions are provided on the outer peripheral surface side of the core metal and in the circumferential direction of the core metal. A convex portion on the outer peripheral surface of the cored bar is formed of a material fixed to the outer peripheral surface of the cored bar, and the material has a thermal conductivity equivalent to that of a crystallized phase change material. A fixing roller, characterized in that: 2. In the convex portion on the outer peripheral surface side of the metal core, the shape of the metal core in a section perpendicular to the axis is a trapezoid whose lower base is located on the metal core side, or whose base is located on the metal core side and the vertical angle is 2. The fixing roller according to claim 1, wherein the fixing roller has an acute triangle and a height thereof is smaller than a thickness of the heat generating layer. 3. A heating layer made of a phase change material capable of phase transition between crystalline and amorphous is provided between the core metal and the protective layer in a sealed manner, and the phase change material by heating is provided. In the fixing roller configured so that the temperature rise of the outer peripheral surface is promoted by the heat generated at the time of the phase transition, a plurality of convex portions are provided on the inner peripheral surface side of the protective layer and in the circumferential direction of the protective layer. The projection on the inner peripheral surface side of the protective layer is formed of a material fixed to the inner peripheral surface of the protective layer, and the material has a thermal conductivity equivalent to that of a crystallized phase change material. A fixing roller having a ratio. 4. In the convex portion on the inner peripheral surface side of the protective layer, the shape of the core metal in a cross section perpendicular to the axis is a trapezoid whose lower bottom is located on the protective layer side or whose top is located on the protective layer side. 4. The fixing roller according to claim 3, wherein the angle is an acute triangle with an acute angle, and the height is smaller than the thickness of the heat generating layer.