JPH096170A - Fixing roller - Google Patents

Abstract

PURPOSE: To reduce the warming-up time by providing a heat generating part and an insulating layer outside the heat generating part and providing a phase transition layer transforming the phase between amorphous structure and crystal structure outside the insulating layer. CONSTITUTION: A heat generating layer 21 by energizing is formed by using a hard glass as a core bar 1, milk-printing with a ceramic agent, in which gold(Au) and palladium(Pd) are dispersed, and heating. Next, a heat shrinkable PTFE resin tube as the insulating layer 12 is applied on the surface of the heat generating layer 21 and heated. After that, the phase transition layer 13 is formed in a prescribed thickness by vacuum-depositing a selenium-tellurium(Se-Te) alloy containing tellurium(Te). Further, a protective layer 14 used also for preventing the sticking of a toner is formed by applying a heat shrinkable conductive PFA resin tube on the surface of the phase transition layer 13. In such a case, the input variation of current is suppressed since the heat generation in the heat generating layer 21 by energizing is stabilized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing roller for electrophotography, and more specifically, it is incorporated in an apparatus for thermally fixing a toner image transferred onto a recording sheet by an electrophotographic method in a copying machine, a printer, a facsimile or the like. The present invention relates to a fixing heating roller.

[0002]

2. Description of the Related Art An electrophotographic apparatus, such as a laser printer, has a rotating photosensitive drum, and a photosensitive member portion of the photosensitive drum is uniformly charged by a charging unit, and then a laser beam from a laser scanner unit. Information is recorded as an electrostatic latent image by the toner in the developing unit by attaching toner to the electrostatic latent image, and the toner image is transferred onto the recording sheet conveyed in the transfer unit. The recording sheet is passed through a thermal fixing device to thermally fix the toner image.

In such a conventional heat fixing device,
As shown in FIG. 4, there is used a fixing roller in which a sticking prevention layer 2 made of a fluororesin layer or the like for preventing sticking of toner is provided on the outer peripheral surface of a core metal 1 made of a hollow cylinder such as aluminum. In such a fixing roller, a heater such as a halogen lamp is arranged along the center of rotation in the hollow portion of the core metal, and the radiant heat heats the fixing roller from the inside. A pressure roller that is in pressure contact with the fixing roller is provided parallel to the fixing roller, and the pressure roller and the fixing roller are rotated so as to move in the same direction with respect to the rotation of the fixing roller. The recording sheet is held and moved. Then, during this movement, the toner adhered on the recording sheet is softened by the heat of the fixing roller, and is fused on the recording sheet by the pressure.

However, in such a thermal fixing device, it takes a relatively long warm-up time after the power is turned on at the time of startup until the surface of the fixing roller reaches the required temperature. Therefore, generally, when the main power is turned on, the heater of the fixing roller is also energized to preheat the fixing roller, but this is a waste of power. In order to avoid this, various means for shortening the warm-up time of the fixing roller have been proposed.

That is, by blackening the inner surface of the hollow portion of the roller to increase the copy rate and increase the heat absorption efficiency, a method of similarly providing unevenness on the inner surface to increase the surface area (JP-A-4-34483 and JP-A-4-34483). No. 4-134387), and a method of forming the roller with a heat pipe (Japanese Patent Laid-Open No. 3-1396).
84), a method of heating the roller by electromagnetic induction (actual open flat 4-5
5055), a method in which the roller is made of a conductive elastic material and is energized to directly generate heat (JP-A-4-18627).
0), a method of fixing with a cylindrical heater using a positive temperature coefficient thermistor material (Japanese Patent Laid-Open No. 4-42185). However, in order for these proposals to be effective, it is premised that the heat transfer of the core metal itself is good,
Since there is a limit to reducing the thickness of the core metal of the fixing roller from the viewpoint of mechanical strength, the thermal conductivity of the constituent material of the fixing roller is limited and the effect cannot be sufficiently exerted. There is a problem that it is not practical because it is too much.

[0006]

Therefore, the present invention is capable of shortening the warm-up time without being restricted by the thermal conductivity of the constituent material of the fixing roller, and is desired from the heat generating portion formed on the fixing roller. The present invention provides a novel fixing roller capable of obtaining the heat generation amount.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
This is achieved by a fixing roller characterized in that a heat generating portion and an insulating layer is provided outside the heat generating portion, and a phase transition layer that makes a phase transition between amorphous and crystalline is provided outside the insulating layer. .

Further, in the case of a system in which the base body of the fixing roller itself is a member capable of generating heat, and in the case of a heat generating layer in which a heat generating portion is provided on a cored bar, a general electric wire such as a nichrome wire is wound on the cored bar. There is a method of silk printing gold, vanadium, etc.

The amorphous material provided in the phase transition layer is preferably a material selected from one or more elements belonging to 3B to 6B of the periodic table, such as chalcogen or chalcogenide compound, and selenium ( Melting point of about 217 ° C), selenium-tellurium alloy (melting point of tellurium alone is about 450 ° C), germanium-tellurium alloy (melting point of germanium is about 937 ° C), indium-selenium alloy (melting point of indium is about 156 ° C), indium A tellurium-based alloy, an antimony-selenium-based alloy (melting point of antimony alone is about 631 ° C.), and the like are preferable, and selenium and a selenium-tellurium alloy are particularly preferable. The reason is that when it is cooled and solidified from the molten state, it becomes an amorphous phase, and when it is heated and reaches the crystallization temperature, it rapidly softens to the crystalline phase, but the crystallization temperature is 80 to 200 ° C. This is because the heat of crystallization is concentrated and generated within the range.

Next, as the material of the core metal which is the base of the fixing roller of the present invention, a conventionally used metal having a good thermal conductivity, such as an aluminum alloy or SUS, is used. It is not particularly limited.

When a heat generating layer is provided on the outer surface, an insulating layer may be further provided between the heat generating layer and the cored bar so as to prevent conduction to the cored bar so as to obtain a desired electric resistance.

Further, it is preferable to provide a protective layer for covering the heat generating layer. Generally, in order to crystallize an amorphous material and then to make a phase transition to an amorphous state, the amorphous material is heated to crystallize a solid, and the solidified material is once made into a molten state. To make it amorphous by cooling (quenching) from the first
And the second method in which an amorphous material is heated to crystallize a solid, and the solidified material is ion-implanted to return it to an amorphous state.

In the second method, there is a method of applying a semiconductor manufacturing technique, but in the first method, it suffices to consider only the melting state of the phase change layer. Therefore, it is necessary to provide a protective layer on the phase transition layer so that the material does not flow out when the phase transitions to the amorphous phase. Therefore, it is a condition that the protective layer has heat resistance to maintain the non-melted state even in the melted state of the phase change layer.

When the protective layer is the outermost surface of the fixing roller, it may also serve as a release layer for preventing adhesion of toner or the like. Considering these, the protective layer is preferably made of a fluororesin, and may be provided by covering with a heat-shrinkable tube and heating. At this time, the side portions of the fixing roller can be sealed by making both ends of the fixing roller larger than the axial width (hereinafter, referred to as width) of the fixing roller of the phase transition layer. A release layer may be further provided on the outer layer of the protective layer.

The insulating layer provided between the heat generating portion and the phase transition layer in the present invention has a heat resistance higher than the melting point of the amorphous material of the phase transition layer (for example, when the first method is used). Fluororesin system (PFA, PTFE) with less heat deformation, less molecular decomposition from high molecules to low molecules,
Epoxy resin, PPS resin, polyimide resin, etc. are desirable.

[0016]

The electrical resistance in the amorphous state is remarkably higher than that in the crystalline state. Therefore, when the heat generating portion and the phase change layer are in direct contact, the two resistors form a parallel circuit. Therefore, when a current is applied to the heat generating portion during warm-up, the amorphous phase change layer is formed. Although there is a possibility that a desired amount of heat generated by the heat generating portion may not be obtained due to the shunting of flow toward the material, in the present invention, since the insulating layer is provided between the heat generating portion and the phase transition layer, heat generation It is possible to prevent the partial flow from the portion to the phase transition layer.

When the phase-transition layer is heated by energizing the heat-generating layer, the heat of crystallization is released when the amorphous material reaches the crystallization temperature, the temperature rises rapidly, and the fixing quickly. Reach possible temperature. After that, the temperature is controlled by the normal heat generation of the heater, but after the crystallization, the heat conduction of the material is enhanced, so that the temperature control becomes easier. When the copying operation is completed, a large amount of power is temporarily supplied to the heater or heating layer to heat the crystallized material to a temperature above its melting point, and then the power is turned off to allow cooling or rapid cooling with a fan or the like. By carrying out, the amorphous material layer is returned to again and can be repeatedly used.

In the phase transition layer, firstly, a complete phase transition between an amorphous state and a crystalline state occurs, secondly, a glass transition point Tg is room temperature or higher, and thirdly, a crystallization temperature Tc. Is between room temperature and the fixing temperature Tt (about 200 ° C.),
Fourth, it is desirable to have characteristics such that the melting point Tm for re-amorphization is as low as Tt or higher as much as possible, and fifthly, it does not deteriorate due to repeated crystallization and melting.

Further, as the characteristics of the insulating layer, firstly, heat resistance can be obtained in a molten state of the crystallized material of the phase change layer, and secondly, the heat generating portion (base, heat generating layer, etc.) and the phase change layer. It is necessary to have good adhesion.

[0020]

【Example】

(Example 1) A heat-shrinkable tube (made by Gunze) made of PFA resin to be the insulating layer 12 was coated on the SUS substrate 11 having an outer diameter of 20 mm and a thickness of 0.3 mm and heated at 150 ° C. Then selenium tellurium (S) containing 8% by weight tellurium (Te)
The e.Te) alloy is vacuum-deposited to a thickness of 0.1 mm to form the phase change layer 13. Or thickness 0.
You may vapor-deposit and polish so that it may become 1 mm. Next, a heat-shrinkable tube (made by Gunze) of a conductive PFA resin is coated on the surface of the phase transition layer 13 and heated at 300 ° C. to protect the toner layer having a thickness of about 20 μm, which also serves as a protective layer 14.
To obtain a fixing roller A of the present invention having a sectional structure as shown in FIG. Since the SUS substrate 11 itself serves as a heat generating portion, it is electrically connected to both ends.

(Embodiment 2) Outer diameter 20 mm, thickness 0.5 m
A hard metal of m is used as a core metal 1, and a ceramic agent (made by Noritake Co.) in which gold (Au) and palladium (Pd) are dispersed is silk-printed and heated and baked at about 500 ° C. for 30 minutes to generate an electric heating layer having an electric resistance of 10Ω. 12 is formed. Then, the surface of the electric heating layer 21 was coated with a heat-shrinkable tube of a PTFE resin to be the insulating layer 2 and heated at 150 ° C. Then 3
Se / Te alloy containing 0 wt% Te has a thickness of 0.1 m
The phase transition layer 13 is formed by performing vacuum evaporation so that the thickness becomes m. Further, the surface of the phase transition layer 13 is covered with a heat-shrinkable tube of a conductive PFA resin and heated at 300 ° C. to form a protective layer 14 having a thickness of about 10 μm which also serves as a sticking preventive agent for the toner. The fixing roller B of the present invention having such a sectional structure was obtained. The energization heat generating layer 21 is electrically connected to both ends thereof to generate desired heat.

(Embodiment 3) Outer diameter 20 mm, thickness 0.5 m
m hard glass is coated on the surface of the core metal 1 with a heat-shrinkable tube (made by Gunze) of PTFE resin to be the second insulating layer 31 and heated at 150 ° C. Then, a ceramic agent (manufactured by Noritake Co.) in which gold (Au) and palladium (Pd) are dispersed is silk-printed and heated and baked at about 500 ° C. for 30 minutes to form an electric heating layer 21 having an electric resistance of 10Ω. Next, the surface of the electric heating layer 21 was covered with a heat-shrinkable tube of PTFE resin (made by Gunze) to be the insulating layer 12 and heated at 150 ° C. After that, a Se / Te alloy containing 30 wt% Te is vacuum-deposited to a thickness of 0.1 mm to form the phase change layer 13. Further, the surface of the phase transition layer 13 is coated with a heat-shrinkable tube (made by Gunze) of a conductive PFA resin and heated at 300 ° C. to form a protective layer 14 having a thickness of about 10 μm and also for preventing adhesion of the toner. A fixing roller C of the present invention having a sectional structure as shown in FIG. 3 was obtained.

[0023]

According to the present invention, since the amount of heat generated in the heat generating portion is stable, it is possible to suppress the input fluctuation of the current, so that a uniform surface temperature distribution can be obtained and a good fixing property can be obtained. , The warm-up time can be shortened remarkably by the heat of crystallization at the phase transition from amorphous to crystalline by the phase transition layer, and the thermal conductivity becomes higher after crystallization, so the temperature equalization is improved. The offset is less likely to occur.

[Brief description of drawings]

FIG. 1 is a sectional view showing a structure of a fixing roller according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the structure of a fixing roller of Example 2 of the present invention.

FIG. 3 is a cross-sectional view showing a structure of a fixing roller of Example 3 of the present invention.

FIG. 4 is a cross-sectional view showing the structure of a conventional fixing roller.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 core metal, 2 adhesion prevention layer, 11 base | substrate, 12 insulating layer, 13 phase transition layer 14 protective layer, 21 electric heating layer, 31 2nd insulating layer

Claims (7)

[Claims] 1. A fixing roller for transferring toner onto a recording medium by an electrophotographic apparatus and fixing the toner onto the recording medium, wherein a heat generating portion and an insulating layer are provided outside the heat generating portion, and the insulating layer is further provided. A fixing roller, which is provided with a phase transition layer that makes a phase transition between amorphous and crystalline on the outside. 2. The fixing roller according to claim 1, wherein the heat generating portion is a heat generating layer provided outside the cored bar. 3. The fixing roller according to claim 2, further comprising a second insulating layer provided between the core metal and the heat generating layer. 4. The protective layer having a heat resistance higher than or equal to the melting point of the amorphous material of the phase change layer is further provided outside the phase change layer. The fixing roller described. 5. The fixing roller according to claim 4, wherein the insulating layer has heat resistance equal to or higher than the melting point of the amorphous material of the phase change layer. 6. The amorphous material of the phase transition layer is 3 of the periodic table.
The fixing roller according to claim 1, wherein the fixing roller is selected from one or more elements belonging to B to 6B. 7. The fixing roller according to claim 1, wherein the crystallization temperature of the amorphous material in the phase change layer is in the range of 80 to 200 ° C.