JPH08227245A - Heater for heating, heat roller for fixing, and fixing device - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: To minimize the change in resistance value when a thermal cycle is applied by repeating ON-OFF and to maintain the same resistance value as an initial value for a long period of time.
Get. An insulating layer 3 made of an organic resin is formed on the surface of a metal pipe 2, and a heat generating resistor layer 4 formed by mixing a crystallized glass and a conductive material is provided on the insulating layer 3 to provide a fixing heat roller. Make up 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heater for heating, and more particularly to a heat roller for fixing toner and a fixing device in an electrophotographic apparatus such as a printer.

[0002]

2. Description of the Related Art Conventionally, in a toner fixing device in an electrophotographic apparatus such as a printer, a heat roller having a heat generating means and a pressure roller are arranged so as to face each other, and a sheet after printing is passed between these rollers. By doing so, the toner is heated and fixed.

As the heat roller, a metal pipe made of aluminum, stainless steel or the like provided with a heating element such as a halogen lamp has been used. However, since the heat generation efficiency is poor, a warm-up time of 1 minute or more is required. In addition, there is a problem that the power consumption is large.

Therefore, a heating resistor is provided on the outer periphery of the metal pipe through an insulating layer made of an organic resin such as polyimide,
Further, a heat roller having a structure provided with a release layer on its surface has been proposed (Japanese Patent Laid-Open Nos. 55-72390 and 6-62).
2-200380, etc.).

On the other hand, it has also been proposed to use a mixture of glass and a conductive material such as metal as the heating resistor layer of the heat roller (see Japanese Patent Laid-Open No. 63-158582). This is because a conductive material such as a metal has good wettability with glass and is easily adapted to the glass, so that a heating resistor layer having a uniform thickness can be formed.

[0006]

However, in a conventional heat roller having a heating resistor layer formed of a mixture of glass and a conductive material, when the heater roller is repeatedly turned on and off, heating resistor layer is repeatedly heated and cooled. There was a problem that the resistance value of was changed. Therefore, there is a disadvantage that the initial characteristics are changed while the heat roller is used, and the heat roller cannot be used for a long time.

Silver (Ag) is preferably used as a conductive material for the heating resistor layer of the heat roller because it has high electric conductivity and excellent oxidation resistance. But,
Since Ag is difficult to sinter at low temperatures, when an organic resin is used as the insulating layer as described above, it is difficult to sinter the heating temperature, which makes it difficult to sinter the heating resistor containing Ag.

Further, in the conventional heat roller, since the electrode for energizing is on almost the same surface as the outer surface of the heat roller, toner powder or paper powder adheres to the electrode, causing sparks or noise. There was also a problem.

Further, in the conventional fixing device, the heat of the heat roller is radiated in a direction other than the pressure roller side.
There was also a problem that the heating efficiency was poor.

[0010]

Therefore, according to the present invention, a heating heater is constructed by providing a heating resistor formed by mixing crystallized glass and a conductive material on a base body having at least an insulating surface. In particular, the heat roller for fixing is configured by using the above substrate as a pipe.

That is, according to the present invention, by using crystallized glass as the glass forming the heating resistor layer, it is possible to obtain a heat roller having a small change in resistance value with repeated heating and cooling cycles.

Further, according to the present invention, there is provided a heating heater comprising a heating resistor formed by mixing a conductive material containing AgO and glass on a substrate having an insulating property at least on the surface thereof. A fixing heat roller is constituted by using the above-mentioned substrate as a pipe.

That is, according to the present invention, if a conductive material that forms Ag is used as the conductive material forming the heating resistor layer and is fired in an oxidizing atmosphere to generate AgO, Ag can be fired at a relatively low temperature, so that the oxidation resistance is improved. It was found that an excellent heating resistor layer can be obtained.

The heating heater of the present invention can be used not only as a fixing heat roller but also as a liquid crystal substrate or heater for heating various elements, or a heater for fluid heating.

Further, according to the present invention, the electrode for energizing the heating resistor layer is projected from the outer surface of the release layer to prevent the adhesion of toner powder or paper powder.

Further, according to the present invention, by providing a reflector on the side of the heat roller opposite to the pressure roller, the heat radiated in this direction is reflected and the pressure roller side is efficiently heated.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

As shown in the fixing heat roller 1 in FIG. 1, a heating resistor layer 4 is provided on the outer peripheral surface of a metal pipe 2 with an insulating layer 3 interposed therebetween, and a release layer 5 is formed on the outermost surface. ,
Ring-shaped electrodes 6 are attached to both ends of the heating resistor layer 4.

The metal pipe 2 has a thermal conductivity of 0.03 ca.
It is made of a metal of 1 / ° C. · cm · sec or more, and specifically, aluminum, aluminum alloy, stainless steel or the like is used, and the thickness thereof is 0.5 to 1 mm. The insulating layer 3 is made of an organic resin having excellent heat resistance such as polyimide, phenol, silicon, borosiloxane, and the thickness thereof varies depending on the dielectric strength, but in the case of polyimide, a thickness of 10 to 200 μm is preferable. As the polyimide forming the insulating layer 3, one having a small difference in coefficient of thermal expansion from the metal pipe 2 is used. Further, the release layer 5 is made of fluororesin, silicone, or the like, which has excellent releasability from the toner.

When the heat roller 1 is rotated while being energized between the electrodes 6, 6 at both ends by a brush-shaped power feeding member (not shown), the heating resistor layer 4 generates heat and acts as a fixing heat roller. can do.

The heating resistor layer 4 is made of a mixture of glass and a conductive material, and the content of the conductive material in the heating resistor layer 4 is 5 to 40% by weight. This is because if the conductive material is less than 5% by weight, the heating resistor layer 4
Is too high, while 40% by weight
This is because if it exceeds, the adhesion of the heating resistor layer 4 deteriorates and peeling easily occurs.

Further, as the conductive material forming the heating resistor layer 4, a material containing 5% or more of Ag is used, and if it is fired in an oxidizing atmosphere with an oxygen concentration of 1% or more, it can be fired at a relatively low temperature. Since AgO is present in the heat generating resistor layer 4, the oxidation resistance can be increased. The presence of AgO means
This is a layer in which even if a peak of AgO is detected even when the heating resistor layer 4 is analyzed by X-ray diffraction.

Other components include Ni, Au,
Metal materials such as Pd, Mo, Mn, W, or Re
_At least one metal compound such as ₂ O ₃ , Mn ₂ O ₃ and LaMnO ₃ may be used. Of these ingredients, A
As described above, g has high electrical conductivity and excellent oxidation resistance, and Pd is mainly the temperature coefficient of resistance (TCR).
In addition, metal compounds such as Mn ₂ O ₃ and LaMnO ₃ are used for lowering the TCR and adjusting the specific resistance. Also,
When the TCR of the heating resistor layer 4 is set to 3000 ppm / ° C. or less, the rate of temperature rise is high and local heat generation and temperature variation can be reduced.

Here, the TCR of the heating resistor layer 4 is set to 300.
In order to set the concentration to 0 ppm / ° C. or less, for example, Ag and Pd are used as the conductive material of the heating resistor layer 4, and the weight ratio thereof is A.
It may be set within the range of g / Pd = 0.5 to 19.

Furthermore, by using crystallized glass as the glass forming the heating resistor layer 4, it is possible to obtain the heating resistor layer 4 in which the resistance value changes little even by the heating and cooling cycle. As its composition, one containing 50% by weight or more of PbO is used. This is because it has a low melting point, and it is preferable that the softening point is 500 ° C. or lower. Then, as components other than PbO, B ₂ O ₃ ,
A material containing SiO ₂ , ZnO, BaO, or the like is used.

Further, as the crystallized glass, one having a crystallinity of 0.5 or more is used. Here, the crystallinity is a scale showing the degree of crystallinity of glass, and is measured as follows.

First, the heat-generating resistor layer 4 containing the above-mentioned crystallized glass is crushed and Ni or ZrO 2 is used as a standard sample.
₂ is added in the range of 10 to 100% and mixed. The crushed product was subjected to X-ray diffraction, and from the obtained chart, the ratio P ₁ / P of the PbO crystal peak P ₁ to the standard sample peak P ₂ was obtained.
₂ is obtained and this is defined as the crystallinity. And this P
_If a crystallized glass having a crystallinity defined by ₁ / P ₂ of 0.5 or more is used, the heating resistor layer 4 having a small resistance change due to the heating / cooling cycle can be obtained.

The thickness t of the heating resistor layer 4 is 5-10.
0 μm. This is because if the thickness t is less than 5 μm, the resistance value becomes high and variations easily occur.
This is because if the thickness exceeds μm, peeling easily occurs. The pattern shape of the heating resistor 4 can be changed in various ways such as the entire surface, a strip shape, and a meandering shape according to the required resistance value.

Further, the electrode 6 is formed of nickel-plated brass, copper, copper containing 0.01 to 0.1% of silver, etc., and fixed on the heating resistor layer 4 with silver paste. I am doing it. It is important that the electrode 6 is formed so as to protrude from the outer surface of the release layer 5 by a height h.

That is, when toner powder, paper powder or the like generated when the heat roller 1 is used adheres to the outer peripheral surface of the electrode 6,
This causes inconveniences such as sparks and noise. Therefore, by protruding the electrode 6 from the outer surface of the release layer 5 by the height h, it is possible to prevent the toner powder or the paper powder from adhering to the electrode 6. This height h is
If it is less than 0.1 mm, the above adhesion preventing effect is poor, while 5
If the thickness exceeds mm, it is difficult to assemble it in an actual machine due to a step difference.

Further, by forming a groove around the electrode 6, it is possible to prevent toner powder and paper powder from accumulating in the step portion. This groove may be formed in the axial direction so as to communicate the inside and outside of the stepped portion around the electrode 6.

Next, the heat roller 1 of the present invention shown in FIG.
The manufacturing method of will be described.

First, the metal pipe 2 is processed into a predetermined shape,
The insulating layer 3 made of an organic resin is applied on the surface by spin coating, spray coating, dipping, or the like to form 200 to 4
Bake in 50 ° C. air or nitrogen atmosphere. On this surface, a mixture of glass and a conductive material as described above is mixed with an organic solvent, a binder, a dispersant, etc. to form a paste, which is applied in a predetermined pattern shape by screen printing, dipping, spray coating or the like. 40
It is fired at 0 to 500 ° C. to form the heating resistor layer 4. In addition,
When the heating resistor layer 4 contains Ag, the atmosphere during firing is an oxidizing atmosphere having an oxygen concentration of 1% or more. After that, the electrodes 6 are joined, the release layer 5 is applied by spray coating or the like, and the firing is performed at about 390 ° C.

Even if a heating / cooling cycle is performed during such a manufacturing process, the use of crystallized glass as the heating resistor layer 4 and a material containing AgO results in little resistance change and excellent oxidation resistance. It can be used satisfactorily for a long time.

Further, in the embodiment of FIG. 1, the heat roller 1 having the insulating layer 3 and the heating resistor layer 4 on the outer surface of the metal pipe 2 is shown, but it is not shown as another embodiment, It is also possible to provide the heat roller 1 having a structure in which the insulating layer 3 and the heating resistor layer 4 are provided on the inner surface of the metal pipe 2, while the release layer 5 is provided on the outer surface of the metal pipe 2.

Further, in the above embodiment, an example in which the insulating layer 3 is provided on the surface of the metal pipe 2 is shown, but in addition to this, the pipe itself is formed of an insulating material such as glass, ceramics, resin,
The heating resistor 4 may be provided on the surface. In short, it is sufficient to prepare a pipe having at least an insulating surface and form the heating resistor 4 on this surface. In these cases, a reinforcing member may be provided inside the pipe to improve the strength.

When the heat roller 1 is used,
As shown in FIG. 2, the heat roller 1 and the pressure roller 21 are arranged so as to face each other.
The toner is fixed on top of the second. At this time, the heating efficiency can be improved by providing the reflector 23 on the opposite side of the heat roller 1 from the pressure roller 21.

That is, the heat of the heat roller 1 is radiated in all directions, but only the portion facing the pressure roller 21 is required, and the heat radiated to the opposite side is wasted.
Therefore, by providing the curved reflector 23 along the outer shape of the heat roller 1, the heat radiated to the side opposite to the pressure roller 21 can be reflected and the pressure roller 21 side can be efficiently heated.

The reflector 23 can be made highly reflective by using a metal material or a plastic material, the inner surface of which is metallic color or white and the surface roughness (Rz) of the inner surface of which is 100 μm or less. Also, the reflector 23
The smaller the thickness, the less power loss, so 0.1-1
It is efficient to have a thickness of mm and to stack a plurality of thin members. Further, if the distance d between the reflector 23 and the heat roller 1 is too short or too far, the efficiency becomes poor,
The range of 0.1 to 10 mm is preferable. It is more effective to coat the inner surface of the reflector 23 with a substance that emits far infrared rays.

Further, in the above embodiments, only the cylindrical fixing heat roller is described, but the present invention is not limited to this.

For example, the heating heater 1 shown in FIG.
In No. 1, an insulating layer 13 made of an organic resin is formed on a metal plate 12, and a heating resistor layer 14 made of glass and a conductive material is provided on the insulating layer 13. The material of each member, the material of the heating resistor layer 14 and the like are all the same as in the above embodiment.

Instead of the metal plate 12 and the insulating layer 13, it is also possible to form a substrate with an insulator such as glass, ceramics, resin, etc., and form the heating resistor 14 on the surface. In short, it is sufficient to prepare a substrate having at least an insulating surface and form the heating resistor 14 on this surface. Further, although the drawing shows the example in which the heating resistor 14 is applied to the entire surface, it may be formed in a predetermined pattern shape such as a strip shape or a meandering shape.

This heating heater 11 is preferably used as a fixing heater similar to the above-mentioned embodiment, or as a general heater for heating various gases and fluids, and for heating various elements. You can As in the embodiment of FIG. 1, even if a heating / cooling cycle is applied during the manufacturing process or during use, the resistance change of the heating resistor layer 4 is small and the oxidation resistance is high, so that it can be used satisfactorily for a long time. be able to.

For example, the heating heater 11 can be used for heating the liquid crystal panel. In this case, the metal plate 1
An aluminum plate having high thermal conductivity is used as 2, and a polyimide film is coated on the surface of the aluminum plate to a thickness of 20 to 30 μm to form the insulating layer 13. A heat-generating resistor layer 14 is formed on the insulating layer 13 by using a material obtained by mixing crystallized glass and Ag, Pd, Ag—Pd, or the like so as to have a uniform temperature pattern. Then, in the atmosphere 5
After firing at 00 ° C., an electrode is formed using a composite material of Ag and a polyimide resin, and if necessary, a protective layer (not shown) that covers the heating resistor layer 14 is formed of resin or the like. Then, the liquid crystal panel can be heated by placing the liquid crystal panel thereon and energizing the heating resistor layer 14.

As another embodiment, the fluid heating heater 21 shown in FIG. 3B can be used. In this case, a heating resistor layer 24 formed by coating an insulating layer 23 of polyimide or the like on the outer circumference of a metal pipe 22 of aluminum or the like and mixing glass and a conductive material is provided with a controller 25 in the heating resistor 24. A voltage can be applied via the. The fluid can be heated by energizing the heating resistor layer 24 while passing the fluid through the metal pipe 22. At this time, the controller 25
If a thermistor or the like is connected to and the temperature of the fluid is detected, the applied voltage can be adjusted so that the fluid can be heated to a predetermined temperature.

Further, it goes without saying that the present invention can be applied to heaters of various shapes and uses other than those shown in the above embodiments.

[0047]

EXPERIMENTAL EXAMPLE 1 As an example of the present invention, a metal pipe 2 made of an aluminum alloy and having a wall thickness of 0.7 mm, an outer diameter of 18 mm and a length of 260 mm was prepared, and an insulating layer made of polyimide was formed on the metal pipe 2. 3 with a thickness of 10 to 50 μm, withstand voltage of 1.5
It is formed to have a voltage of at least kV, and PbO is added to this surface in an amount of 5
70% by weight of crystallized glass containing 0% or more, Ag and Pd,
A heating resistor layer 4 was formed by coating a mixed resistor powder with 30% by weight of a conductive material such as LaMnO ₃ and baking it at 450 ° C. to crystallize the glass.

Electrodes 6 were attached to both ends of the heating resistor layer 3, and a release layer 5 was formed on the surface with a fluororesin to obtain the heat roller 1 of the present invention shown in FIG.

On the other hand, as a comparative example, the same as the above,
As the glass forming the heating resistor layer 4, a glass using non-crystallized glass was prepared.

For these heat rollers 1, 370 ° C.
The resistance value R after reheating for 30 minutes at three times was measured, and the resistance change rate (R−R ₀ ) / initial resistance value R ₀ was measured.
R was calculated. The results are shown in FIGS. 4 (a) and 4 (b).

From this result, it is clear that the comparative example (see FIG.
In (b), there was a resistance change of about 20% after reheating three times. On the other hand, in the example of the present invention (FIG. 4 (a)), there is only a resistance change of about ± 1% after reheating three times, and it can be seen that the resistance change due to the heat cycle is extremely small.

Experimental Example 2 Next, in the heat roller 1 of the present invention, the ones having different crystallinity were prepared by changing the firing conditions of the heating resistor layer 4 as shown in Table 1.
After repeating the thermal cycle between 40 ° C and 180 ° C for 20000 cycles, the resistance change rate (%) with respect to the initial resistance value
And 3% or less were evaluated as ◯ and those exceeding 3% were evaluated as x.

Regarding the crystallinity, as described above, 10 to 100% of Ni or ZrO ₂ as a standard sample was added to and mixed with the one obtained by peeling off the heating resistor layer 4 and mixed with this pulverized product. The crystallinity was defined as the ratio P ₁ / P ₂ between the peak P ₁ of the PbO crystal and the peak P ₂ of the standard sample when line diffraction was performed.

The results are shown in Table 1, and the crystallinity is 0.5.
If it is above, the resistance change rate after 20,000 cycles is 3
It was found that the resistance value was as low as%, and the initial resistance value could be maintained even under thermal cycling.

[0055]

[Table 1]

Next, the thickness t of the heating resistor layer 4 was variously changed, and No. 1 in Table 1 was changed. The heat roller 1 was prototyped under the conditions of No. 4. In each case, the case where the specific resistance was within ± 10% of the target value was evaluated as ◯, and the case where it was outside this range was evaluated as x. In addition, when a healing test was performed in which a cellophane tape was attached to the heating resistor layer 4 and peeled off, those without peeling of the heating resistor layer 4 were evaluated as ◯, and those with peeling were evaluated as x.

The results are shown in Table 2. From this result, when the thickness t of the heating resistor layer 4 is less than 5 μm, it is difficult to set the target value due to large variation in resistance value, while when the thickness t exceeds 100 μm, peeling easily occurs. It was found that the film thickness is preferably in the range of 5 to 100 μm.

[0058]

[Table 2]

Experimental Example 3 Next, as the conductive material forming the heating resistor layer 4, only the one using Ag and the one using Ag and Pd (Ag: Pd = 1: 1) were used. The specific resistance and the temperature coefficient of resistance (TCR) of the heating resistor layer 4 were measured when the content of the conductive material therein was changed.

As shown in the results in FIG. 5, in any case, the specific resistance can be lowered by increasing the content of the conductive material, and the inclusion of Pd can increase the specific resistance and reduce the TCR. Recognize.

Therefore, by changing the composition and content of the conductive material, the resistance value and TC of the heating resistor layer 4 can be changed.
It can be seen that the R value can be adjusted freely.

The temperature coefficient of resistance (TCR) of the heating resistor layer 4 was measured while changing the ratio of Ag and Pd in various ways. As shown in Table 3, the TCR of TCR was changed according to the ratio of Ag / Pd. The value changes and the Ag / Pd ratio is changed from 0.5 to 19
Within the range, it can be preferably used.

[0063]

[Table 3]

Experimental Example 4 Next, in the same manner as in the above experimental example, the ratio of the glass forming the heating resistor layer 4 to the conductive material was variously changed, and the specific resistance, peel strength and ON-OFF test were performed. The resistance change was measured.

The peel strength is a load required for vertically peeling the heating resistor layer 4 within a range of 2 × 5 mm, and is ON.
In the OFF test, the inrush power is 800 W and the heater temperature is 200.
A voltage was applied for 1 minute so that the temperature became 0 ° C., and a cycle of cutting off the voltage for 2 minutes was repeated 50,000 cycles, and then the resistance change rate was measured. If the rate of change in resistance was within 3%, it was judged as good.

The results are shown in Table 4, and the conductive material is 5 to 4
It can be seen that it is suitable to set the range of 0% by weight and the range of 95 to 60% by weight of glass.

[0067]

[Table 4]

Experimental Example 5 Next, in the same manner as in the above experimental example, the ratio of the glass forming the heating resistor layer 4 to the conductive material was variously changed, and the firing rate was changed to change the production rate of AgO. It was In the same manner as in Experimental Example 4, the peel strength and the resistance change after the ON-OFF test were measured. The production rate of AgO was measured by Auger analysis and expressed as a ratio of AgO / Ag.

As shown in Table 5, the firing temperature is 45
It can be seen that those having a temperature of 0 ° C. or higher and a ratio of AgO / Ag of 0.08 or more have a small resistance change after the ON-OFF test and have excellent durability.

[0070]

[Table 5]

[0071]

As described above, according to the present invention, a heater for heating is provided by providing a heating resistor layer formed by mixing crystallized glass and a conductive material on a substrate having at least an insulating surface. With this configuration, it is possible to extremely reduce the change in resistance value when a thermal cycle is applied by repeating ON-OFF.

Further, according to the present invention, since the mixture of the conductive material containing AgO and the glass is used as the heating resistor layer, the heating resistor layer can have high oxidation resistance.

In particular, when the above-mentioned substrate is used as a fixing heat roller in the form of a pipe, it is possible to provide a fixing heat roller which maintains its initial performance for a long period of time and has a long life.

Furthermore, according to the present invention, the electrodes of the heat roller are made to project from the outer surface of the release layer, so that toner powder and paper powder are prevented from adhering to the electrodes, and sparks and noise are not generated. Can be prevented.

Further, according to the present invention, by providing the reflector on the side opposite to the pressure roller of the heat roller, the heat radiated to the opposite side can be reflected to efficiently heat the pressure roller side. it can.

[Brief description of drawings]

FIG. 1 is a partially cutaway side view showing a fixing heat roller of the present invention.

FIG. 2 is a sectional view showing a fixing device of the present invention.

3A and 3B are perspective views showing a heating heater of the present invention.

FIG. 4 is a graph showing the relationship between the number of times of reheating and the resistance change rate in the fixing heat roller, in which (a) is an example of the present invention and (b) is a comparative example.

FIG. 5 is a graph showing the relationship between the content of the conductive material in the heating resistor layer and the specific resistance in the fixing heat roller of the present invention.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinsuke Takenishi 1-1, Yamashita-cho, Kokubun-shi, Kagoshima Prefecture Kyocera Kokubun Plant

Claims (6)

[Claims] 1. A heater for heating, comprising a heating resistor formed by mixing crystallized glass and a conductive material on a substrate having at least an insulating surface. 2. A heater for heating, comprising a heating resistor formed by mixing a conductive material containing AgO and glass on a substrate having at least an insulating surface. 3. A fixing heat roller comprising a heating resistor layer formed by mixing crystallized glass and a conductive material on a pipe having at least an insulating surface. 4. A fixing heat roller comprising a heating resistor layer formed by mixing a conductive material containing AgO and glass on a pipe having at least an insulating surface. 5. A heat roller comprising a heating resistor layer and a release layer on a pipe having an insulating property at least on the surface, and having electrodes for energizing the heating resistor layer at both ends, wherein the electrode is the electrode. The fixing heat roller is characterized in that is protruding from the outer surface of the release layer. 6. A fixing device in which a fixing heat roller and a pressure roller are arranged to face each other, and a reflector for reflecting heat is provided on a side of the fixing heat roller opposite to the pressure roller.