JPH11287238A - Heating roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a temperature distribution over the whole surface of a roller by arranging a heating layer, in which a plurality of heating elements made of a PTC characteristic substance are connected together in parallel electrically in the roller axial direction according to a pattern arrangement on the same plane, in a heating roller for a fixing device for an electronic photocopy machine and the like. SOLUTION: In a heating roller 1, a mold releasing layer 11 is formed in the outer circumference of a base body 12, while on the inside face of the base body 12, an insulating layer 13, a heating layer 14, and an electrode are arranged. The heating layer 14 is formed by connecting two heating elements R1 , R2 made of PTC characteristic material together in parallel electrically in the roller axial direction according to a pattern arrangement on the same plane. In usage of this kind of heating roller 1 as a fixing roller, for example, when a temperature of the left side heating element is lowered because of passage of paper and the like, resistance of this heating element is reduced and a heating value V<2> /R1 is increased higher than N<2> /R2 , so that the temperature in the axial direction of the heating roller 1 works so as to be unified, and consequently, the temperature of the heating layer 14 is unified.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrophotographic copying machine,
The present invention relates to a heat generating roller of a fixing device used for an apparatus using an electrophotographic process, such as a facsimile and a printer, and may be applied to a heat roller for erasing a rewritable recording card.

[0002]

2. Description of the Related Art As a fixing method of a toner image, a heat fixing method, a pressure fixing method, and a solvent fixing method are known.
The heat fixing method is a method in which toner is melted by heat and pressure is applied to paper to fix the paper, and is widely adopted.
The most common of the heat fixing methods is a method of heating with a halogen lamp from inside a metal roller. However, this type has a drawback that the radiant heat is used, so that the energy conversion efficiency is low, the power consumption is large, and the warm-up time is long.

Therefore, as one of means for solving such a drawback, a fixing roller of a direct heating type using a heating roller in which a heating layer is disposed inside or outside a base (namely, a metal core) has been proposed. .

The direct heating type fixing roller has advantages such as a shorter warm-up time and less power consumption than the indirect heating method using the halogen lamp. However, when several types of copy paper having different paper widths are passed, there is a common drawback with the indirect heating method in that a difference occurs in the temperature distribution between the paper passing portion and the non-paper passing portion. In general, the copy paper passes through the center of the fixing roller, and at that time, heat is taken away by the paper, so that the temperature at the roller end becomes higher than that at the center, and when the center is heated to an appropriate temperature, The temperature at the end of the roller is too high (hereinafter, referred to as an end temperature increase). Usually, the edge temperature rise occurs when narrow paper is continuously passed. When wide paper is passed in a state where the edge temperature rises, an image defect called an offset occurs because the roller edge is higher than a temperature suitable for fixing. Conversely, since heat is radiated from both ends of the heat generating roller, there is a disadvantage that the temperature of the end is low at the time of startup.

[0005] As a method of solving such a problem,
When the heat generating layer has a PTC characteristic (a characteristic in which the electric resistance increases as the temperature rises, that is, the temperature coefficient of resistance is positive),
It has been proposed to arrange an even number of electrodes on the heat generating layer, connect an odd numbered electrode and an even numbered electrode from one end of the roller to form a parallel circuit, and achieve a uniform temperature distribution. ing. In this method, it is sufficient to arrange the heat generating layer approximately uniformly over the entire roller, and there is an advantage that the temperature distribution can be made uniform by appropriately arranging the electrodes on the heat generating layer. However, the fact that this method requires at least two electrodes in addition to the two electrodes at both ends which are required at the minimum causes the following inconveniences. That is, since a large current flows through the heating element in the energizing heating element, the reliability of contact between the electrode portions is important, but it is difficult to ensure the reliability of this connection portion.

As a heating element used for the heating roller, there is a heating element in which a meandering pattern is formed by a foil-shaped resistor. This is because the resistance value is adjusted by increasing the length of the current supply path, and the power consumption is set to a desired value. However, in a simple meandering pattern, the creepage length of the cut surface (hereinafter, referred to as creepage length)
However, when the heat generating roller is manufactured, the heat generating roller is likely to be scattered, which is extremely difficult to handle. In addition, even if this inconvenience does not cause a problem during manufacturing, the heating element easily peels off from the roller during use, and the temperature of the roller surface does not increase in the area where the heating element has peeled off and floated, and the heating element itself is locally abnormally heated. There is a drawback that causes.

This disadvantage is not limited to the case where the heating element has a meandering pattern. In the heating roller of the direct heating system, uniform and efficient heat conduction cannot be obtained unless the layers are in close contact with each other. For example, if a heating layer made of a linear or foil-shaped resistor is disposed on the inner surface of the base with an insulating layer interposed therebetween, and the heating layer is separated from the insulating layer, the temperature of the roller surface is increased at the separated portion. Does not rise. On the other hand, the heat generation layer itself does not deprive the generated heat to the insulating layer and the substrate, and thus causes local abnormal overheating. Therefore, in the worst case, the insulating layer is broken and a leak occurs. Also,
Even if the insulating layer is separated from the base, the temperature of the roller surface does not increase in that portion. As a cause of the separation of the layers, a difference in linear expansion between the layers can be considered. However, those that are generally used for the insulating layer, such as laminated mica, heat-resistant resin such as polyimide, aramid insulating paper, etc., which have a proven track record in heat-resistant insulation with a thickness of about 10 to 500 μm, all have a higher elastic modulus than metal. In a configuration sandwiched between metal materials, its expansion is dominated by the metal material. Therefore, a difference in the coefficient of linear expansion between the inner surface of the base and the heat generating layer poses a problem.

In order to shorten the heating time of the heating roller, there is a method of reducing the heat capacity of the heating roller. For this reason, it is required to reduce the thickness of the base of the heat generating roller. However, in order to efficiently transfer heat to the object to be heated, the rigidity of the roller is necessary, and a high-elasticity material is also required for the heating element material. Naturally, heat resistance and corrosion resistance are required. Can be For such a purpose, the heat capacity per elastic modulus is important as a material property. This is advantageous in that iron is 57% of aluminum when compared with iron and aluminum which are widely used as base materials. However, there are disadvantages in that (1) thermal conductivity is 30% of that of aluminum and temperature unevenness easily occurs, and (2) rust is generated, so that rust prevention treatment is required. If it is a SUS alloy,
There is no problem with rust, and the heat capacity per elastic modulus is 65% of aluminum, which is equivalent to iron. However, since the thermal conductivity is extremely small, 7 to 12% of that of aluminum, temperature unevenness is very likely to occur and has not been put to practical use.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to eliminate the above-mentioned disadvantages and to provide a heat generating roller having a simple structure and a good temperature distribution over the entire surface of the roller. One issue. It is a second object of the present invention to solve the above-mentioned problems and to construct a heat generating layer which is easy to handle and can cope with thinning of the substrate.

[0010]

The first object is to provide a PT.
A heating roller is characterized in that a heating layer is formed by electrically connecting a plurality of heating elements made of a substance having the C characteristic in parallel in at least a roller axial direction by pattern arrangement in the same plane. . Further, the second problem is that the heating element is formed of a foil-shaped resistor having a meandering pattern, and the meandering patterns of the heating elements located adjacent to each other in the roller axis direction have the same pitch and the meandering direction is different. This problem is solved by the heat generating roller described above, wherein the heat generating elements are electrically connected in parallel in the roller axial direction by integrating the meandering patterns at the meandering top.

[0011]

Next, an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic sectional view of one embodiment of a heat generating roller according to the present invention. The heat generating roller 1 has a release layer 11 on the outer periphery of a metal base (that is, a metal core) 12.
Is formed, and the (multi-layer) insulating layer 13 and the heat generating layer 1 are formed on the inner surface of the substrate.
4 and electrodes (not shown).

As shown in FIG. 2A, the heating layer is divided into two heating elements in the axial direction of the roller, and these are arranged by pattern arrangement in the same plane (that is, the heating elements are provided with patterns in the same plane, The case where the heating elements are electrically connected in parallel will be described. Here, a heating element having PTC characteristics (resistance increases as the temperature rises and resistance decreases as the temperature falls) is considered.

Assuming that the resistance of the heating element on the left side of FIG. 2A is R ₁ and the resistance of the heating element on the right side is R ₂ , they form a parallel circuit as shown in FIG. 2B. At this time, a power supply voltage V is applied to each of these heating elements, and V ² / R ₁ [heating value is current (V / R ₁ ) × voltage (V)], V ² / R ₂ [heating value] Generates Joule heat of current (V / R ₂ ) × voltage (V)]. For example, when the heat generating roller is used as a fixing roller, when the temperature of one of the heat generating elements, for example, the left side, becomes low due to paper passing or the like, the resistance of the heat generating element decreases due to the PTC characteristic, and the heat generation amount V ² / R. ₁ increases from V ² / R _2, and acts in a direction to make the temperature in the axial direction of the heat generating roller uniform.

On the other hand, as shown in FIG.
The thermal layer is divided into two heating elements in the axial direction and electrically connected in series.
If connected, set the resistance of the left heating element to R₁₀, Right
The resistance of the heating element of R₂₀Then, as shown in FIG.
A series circuit. In this case, it differs from the case of FIG.
Each of these heating elements has V × R₁₀/ (R
₁₀+ R₂₀), V × R₂₀/ (R₁₀+ R₂₀)
Pressure is applied. Therefore, V²× R₁₀/ (R₁₀
+ R₂₀)²[The amount of generated heat is current (V / (R₁₀+
R ₂₀)) × voltage (V × R₁₀/ (R₁₀+
R₂₀))], V²× R₂₀/ (R_{1 0}+ R₂₀)
²[The amount of generated heat is current (V / (R₁₀+ R₂₀)) × voltage
(V × R₂₀/ (R₁₀+ R₂₀))]
Occur. Depending on the paper passing etc.
When the temperature of the heating element decreases, the PTC characteristic causes
Body resistance R₁₀Of the heating element on the left side
The calorific value is smaller than the calorific value of the right heating element.
It works in the direction to increase the temperature difference in the direction.

As described above, when a plurality of heating elements having PTC characteristics are electrically connected in parallel, there is an effect of eliminating the temperature difference and making the temperature difference uniform. In addition, the temperature of the heat generating layer is easily made uniform.

However, if it is divided into too many parts, the temperature will be uniform, but the pattern will be complicated, the production means will be limited to etching and the like, and the heating element will be thin and easily broken. Therefore, the heat radiation from the roller end, the temperature rise at the end, which is the largest cause of an axial temperature difference when the fixing roller is used, the size of paper that can be passed, etc. It is advantageous to divide into effective numbers.

Example 1 A roller was manufactured using a heat generating layer having a structure as shown in FIG. A heating element pattern was formed by etching or pressing using a SUS304 foil having a thickness of 40 μm having a positive temperature coefficient of resistance for an aluminum alloy having a diameter of 30 mm and a heating layer having a positive resistance temperature coefficient. A PFA resin was used for the release layer, and a mica sheet was used for the insulating layer. The width of the entire heat generating layer was set to 300 mm, which was slightly longer than the A4 vertical width (297 mm), and divided by the A4 horizontal width (210 mm). In the example shown in FIG. 2A, the left end of the heating element is divided so as to have an A4 width based on the paper passing reference on the left end. The line width (pattern width) of the heating element pattern was adjusted so that the heat generation density of the heat generating layer became uniform (the line width of the pattern is indicated by a thin line and a thick line in the figure).

When a sheet of A4 width is continuously passed using the fixing roller having such a configuration with the left end as a reference, if the temperature of the right end of the roller becomes higher than that of the left side, the right side of the roller will have a PTC characteristic, so As a result, the calorific value of the right end portion was reduced, and the width of the temperature distribution was reduced. The roller surface temperature difference was 20 ° C. or less. After continuously passing A4 width paper, A4 length paper was passed.
No offset occurred.

A similar experiment was conducted using a heating layer having a heating element pattern as shown in FIGS. 3 to 7 instead of the heating layer having the heating element pattern shown in FIG. 2A. In each case, the roller surface temperature difference was 10 ° C. to 30 ° C., which was smaller than Comparative Example 1 described below.

Comparative Example 1 A paper-passing test similar to that of Example 1 was performed using a fixing roller having a heat generating layer having a configuration as shown in FIG. At that time, the heating element pattern line width was adjusted so that the heating density of the heating element was equalized and the same as in Example 1. As a result, the roller surface temperature difference was 50 ° C. After passing A4 width paper continuously, and then passing A4 length paper, offset occurred.

Example 2 A roller was manufactured using a heating element having the structure shown in FIG. An aluminum alloy having a thickness of 1 mm and a diameter of 30 mm was used as a substrate, and a SUS316 foil and a carbon film were used as heat generating layers, respectively, and patterns were formed by etching or cutting by pressing. A PFA resin was used for the release layer, and a mica sheet was used for the insulating layer. The overall heat generation width was 300 mm, which was slightly longer than the A4 vertical width (297 mm).

A pressure roller made of silicone rubber with a diameter of 30 and a unit were constituted by the heat generating roller having the above-mentioned structure, and a sheet of A4 width was continuously passed through the center as a reference, and the surface temperature difference was measured. Further, the surface temperature difference immediately after the temperature rise was also measured. Further, heating and cooling were repeated 10,000 times, and the durability was confirmed.

The results of the above experiments using the heating layers having the patterns shown in FIGS.
The results are shown in Table 1. Comparative Example 2: The heating element pattern shown in FIGS. 19 and 20 was used. Since these heating element patterns have a longer creepage distance of the cut surface than those obtained by integrating a plurality of heating elements shown in FIG. 9 to FIG. It was difficult to install the heating element at a desired position so as not to come into contact with the device, and it took time to finely adjust the position.

[0024]

[Table 1]

In the second embodiment, since the paper is fed on the basis of the center, a heat generating layer having PTC characteristics (in this case, SUS31)
6) is divided into three parts at the center and both ends in the roller axis direction (FIGS. 10, 14, and 15), which is suitable in that the difference in roller surface temperature during paper passing is reduced. However, if the paper passing reference is the roller end, the two divided patterns as shown in FIGS. 9 and 11 are sufficiently considered.

In order to reduce the temperature difference at the time of raising the temperature, in the case of the heating layer having the PTC characteristic, as shown in FIGS. 14 and 15, the amplitude of the meandering pattern of the heating elements located at both ends is reduced. It is advantageous to reduce the size of the heating element at the center and / or to increase the pattern line width of the meandering pattern at both ends. As far as the point of reducing the temperature difference at the time of raising the temperature is reduced, as shown in FIGS. 16 and 17, the heat generating layer is divided into a central portion and both end portions in the roller axial direction, and these are electrically connected in series. It is also effective to take measures such as making the line width of the pattern of the heating element at both ends narrower than the central part, and making the width between pattern lines narrower than the central part. However, in this case, if a heating element having the PTC characteristic is used, the temperature difference at the time of paper passing acts in a direction to increase, and therefore a heating element having the NTC characteristic is preferably used.

It can be seen that the heat generating layer having the patterns shown in FIGS. 9 to 17B is generally superior in durability to the heat generating layers having the patterns shown in FIGS. 19 and 20.

As a reference example, the same experiment as in Example 2 was performed with the thickness of the substrate set to 0.7 mm. Although the heating time was shortened, when a carbon film was used as the heating element, the occurrence of bending was observed, and the occurrence of wrinkles frequently occurred during paper passing, which made practical use difficult.

In the first and second embodiments, the SU
S304 and SUS316 were used as heating elements, but metal heating elements such as nickel chromium alloy and iron chrome alloy
Conductive pastes having C characteristics, such as metal powder and carbon, are also heating elements having PTC characteristics. If it is a liquid material such as a conductive paste, the pattern can be printed. In addition, many of semiconductors besides the carbon film are shown as those exhibiting the NTC characteristic (the temperature coefficient of resistance is negative).

Next, a description will be given of a combination of the material of the inner surface of the base and the material of the heat generating layer, which is advantageous for ensuring the adhesion of each layer constituting the heat generating roller for a long period of time.

Gold that can withstand the large current density required for resistance heating
The genus heating elements include (1) a large volume resistivity, and (2)
(3) resistant to repeated heating
And (4) good corrosion resistance. So
SUS alloys, nickel
Ruchrome alloys are widely used. These alloys are wire
It is roughly divided into two based on the expansion rate. That is, one
Is (A) austenitic SUS alloy (SUS304, 30
1, 316 etc .; coefficient of linear expansion 14.4-17.3 × 10^-6/ ℃), Ni
Kerchrome alloy (linear expansion coefficient 14.4-17.0 × 10^-6/ ℃) and others
One is (B) martensitic SUS alloy (SUS410S, 4
20J2; coefficient of linear expansion 9.9 to 10.3 × 10 ^-6/ ° C), ferrite
SUS alloy (SUS405, 430, 444, etc .; linear expansion coefficient 9.9-1)
0.7 × 10^-6/ ° C).

Examples 3 to 5 and Comparative Examples 3 to 5 shown in Table 2
In this case, a roller having a configuration as shown in FIG. 1 was used. The base is φ3
The heat generating layer was formed of a metal foil patterned to have a desired resistance, or a tape-shaped metal foil or metal wire spirally arranged to have a desired resistance. The insulating layer was made of laminated mica, polyimide or aramid insulating paper. A PFA resin is applied to the roller surface as a release layer. Substrate thickness is 0.8 for aluminum
mm, and 0.35 mm for iron. In both cases, the magnitude of deflection of the rollers was comparable. The unit of the coefficient of linear expansion in the table is × 10 ⁻⁶ / ° C.

[0033]

[Table 2]

On the other hand, in Examples 6 to 11, the rollers having the structure shown in FIG. 18 were used. The base 12 is made of aluminum having a thickness of 0.4 mm, and a SUS alloy layer having a thickness of 0.15 mm is disposed as an intermediate layer 15 inside the base. That is, this alloy layer forms the inner surface of the base. Other configurations are the same as those based on the configuration of FIG. 1 described above. The magnitude of the deflection of the roller configured as described above was determined in Examples 3 to 5.
It was the same as the roller used in. The unit of the coefficient of linear expansion in the table is × 10 ⁻⁶ / ° C. The intermediate layer may be a seamless pipe, but it is difficult to make it thin with a double pipe of aluminum and SUS, a so-called clad pipe. Therefore, the intermediate layer is preferably formed by winding or winding a SUS foil one or more times into a pipe by bonding or welding.

[0035]

[Table 3]

In Examples 3 to 11 and Comparative Examples 3 to 5, the respective heating rollers and the pressure rollers made of foamed silicone rubber having a diameter of 30 mm as described above using the materials shown in Tables 2 and 3 were used. And a unit was constructed, and the surface temperature difference of the paper passing portion was measured by thermography. Further, heating and cooling were repeated 10,000 times, and durability was confirmed.

As for the heating time, power of 1200 W is supplied,
The time required to raise the temperature from room temperature 25 ° C. to the fixing temperature 180 ° C. was measured. If the temperature is uneven, the toner fixing rate varies. When there is unevenness of 30 ° C. or more, it is difficult to obtain stable fixing. When the substrate is iron, temperature unevenness tends to occur, but as can be seen from the results shown in Table 2,
When ferrite-based SUS was used for the heat generating layer (Example 3), the temperature unevenness was small. When the substrate was made of aluminum, temperature unevenness was unlikely to occur, but when ferrite-based SUS was used for the heat generating layer as in Comparative Example 5, the temperature unevenness increased. As can be seen from the results of Examples 6 to 11, in the heat generating roller in which the intermediate layer made of the SUS alloy is disposed inside the aluminum base, the temperature rise is close to that of the iron base regardless of the type of the heat generating layer used. Time was obtained. Further, the result regarding the temperature unevenness was also good.

Observation of the inside of the heat generating roller where the temperature unevenness became large revealed that the heat generating layer was separated. Therefore, in the heat generating roller in which a heat generating layer made of a linear or foil-shaped metal resistor is disposed on the inner surface of the metal base via an insulating layer, as in the case of Example 4 or Example 5, the metal base is made of aluminum. When the heat-generating layer is made of an austenitic stainless steel alloy or a nickel-chromium alloy, the difference in the coefficient of linear expansion between the inner surface of the base and the heat-generating layer becomes small, and the heat-generating layer does not separate even after repeated heating and cooling. Thus, a uniform temperature distribution can be obtained for a long period of time. Similar effects can be obtained by forming the metal substrate from steel and using a ferrite-based or martensitic-based stainless alloy for the heating layer as in the third embodiment.

Further, as in the case of Examples 6 to 11, when a metal substrate is formed of an aluminum alloy and a stainless steel alloy layer is provided on its inner surface, a martensitic or austenitic stainless steel alloy or nickel chromium Similar effects can be obtained by using an alloy for the heat generating layer. In these cases, since the base is made of aluminum having a high thermal conductivity, the temperature distribution is particularly likely to be uniform. In addition, since the SUS alloy layer having a small heat capacity per elastic modulus is disposed on the inner surface of the base, a heat roller having a low heat capacity and a high rigidity can be obtained, and a heating time close to that of an iron base can be obtained. Since SUS and aluminum do not generate rust, they are also advantageous in that rust prevention treatment is not required as in the case of an iron base.

Although the above-described embodiment is a fixing roller, the present invention can be widely applied to an electrophotographic heating roller such as a pressure roller or a fixing roller heating roller as shown in FIG.

[0041]

According to the heat generating roller according to the first aspect of the present invention, PT
Since a plurality of heating elements having C characteristics are electrically connected in parallel in the roller axis direction to form a heating layer, the end temperature rise can be reduced by self-control without using a special device. Therefore, the roller surface temperature distribution can be made uniform. Further, since the heat generating layer can be formed as a continuous body on the same plane, only minimum required electrodes at both ends are required, and high reliability can be obtained.

In the heat generating roller according to the second to fourth aspects, the heat generating layer includes a heat generating element near a paper passing reference where paper is always passed.
Since each of the heating elements having other heating elements and having PTC characteristics controls the amount of heat generated by itself, it is possible to effectively suppress temperature unevenness generated by continuous paper passing.

In the heat generating roller according to the fifth aspect, since the heat generating density (heat generation amount / area) of the heat generating elements located at both ends of the roller is larger than the other heat generating elements, the temperature generated by the heat release from the ends at the time of start-up. Unevenness can be suppressed.

In the heat generating roller according to the sixth aspect, the heat generating layer has a shape in which a plurality of meandering patterns having the same pitch and opposite to the adjacent pattern are integrated at the meandering top. The creepage length is shortened, the rigidity of the heat generating layer itself is maintained, and the roller is easy to handle and efficient at the time of manufacturing the roller. In addition, the heat generating layer can be stably used for a long time without coming off the roller.

In the heat generating roller according to the seventh aspect, since the direction connecting the start point and the end point of the meandering pattern of each heat generating element is substantially the circumferential direction of the roller, the plurality of resistive elements divided in the axial direction are provided. Are equivalent to a circuit connected in parallel, and P
Due to the TC characteristics, a portion having a low temperature has a low resistance, a large amount of current flows, heat is preferentially generated, and the temperature distribution becomes uniform.

In the heating roller according to the eighth aspect, since the integrated portion of the meandering pattern of the heating element is located at a position substantially equal to the position where the end of the paper that can be continuously passed passes, the heating layer is formed. The parallel circuit exerts its maximum capability in the direction of reducing the temperature difference due to continuous paper passing.

The heating roller according to the ninth to tenth aspects is equivalent to a circuit in which the resistance at both ends of the roller is smaller than that at the center, so that a large amount of current flows at the ends and the amount of heat generated is larger than at the center. Therefore, the temperature drop at the end portion during temperature rise is small, and the temperature distribution becomes uniform.

In the heat generating roller according to the eleventh aspect, the heat generating element has a tendency that the electric resistance decreases due to a temperature rise (NTC).
Characteristic), and since the direction connecting the start point and the end point of the meandering pattern is roughly the axial direction, the heating layer forms a circuit having a resistor connected in series in the axial direction, In this case, the resistance of the portion where the temperature is high decreases, and the calorific value also relatively decreases, so that the temperature distribution becomes uniform.

In the heating roller according to the twelfth and thirteenth aspects, the resistance of the heating element at both ends of the roller is greater than that of the heating element at the center, and the amount of heat generation is greater than that at the center. The temperature drop at the end of is small and the temperature distribution becomes uniform.

In the heating roller according to the present invention, since the heating element is made of stainless steel having a high elastic modulus and excellent heat resistance and corrosion resistance, the rigidity of the heating roller can be increased, and the heating roller can be strongly pressed against the object to be heated. , The contact width can be increased, heat can be efficiently transferred, and it can be used for a long time.

In the heat generating roller according to the present invention, since the difference in linear expansion coefficient between the inner surface of the roller base and the heat generating layer is small, the heat generating layer is not separated even if heating and cooling are repeated. A uniform temperature distribution can be obtained over a long period.

In the heat generating roller according to the present invention, aluminum having high thermal conductivity is used as the core metal, and the temperature distribution tends to be uniform. In addition, since the SUS alloy layer having a small heat capacity per elastic modulus is disposed on the inner surface, the roller has a low heat capacity and a high rigidity, and a heating time close to that of an iron core can be obtained. Further, since rust does not occur in both SUS and aluminum, there is no need for rust prevention treatment unlike iron core metal.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of one embodiment of a heating roller according to the present invention.

FIG. 2A is a diagram of one heating element pattern according to the first embodiment of the present invention, and FIG. 2B is a diagram of an equivalent circuit of the heating element pattern.

FIG. 3 is a diagram of another heating element pattern according to the first embodiment of the present invention.

FIG. 4 is a diagram of another heating element pattern according to the first embodiment of the present invention.

FIG. 5 is a diagram of another heating element pattern according to the first embodiment of the present invention.

FIG. 6 is a diagram of another heating element pattern according to the first embodiment of the present invention.

FIG. 7 is a diagram of another heating element pattern according to the first embodiment of the present invention.

8A is a diagram of a heating element pattern according to Comparative Example 1 for the present invention, and FIG. 8B is a diagram of an equivalent circuit of the heating element pattern.

FIG. 9 is a schematic view of the structure of a heat generating layer according to the present invention,
Is the basic meandering pattern, B is the integrated pattern, C
Is a diagram of the equivalent circuit. Note that the magnitude of the amplitude in the equivalent circuit represents the magnitude of the resistance for convenience.

FIG. 10 is a schematic view of a structure of a heat generating layer according to the present invention;
A is the base meandering pattern, B is the pattern after integration,
C is a diagram of the equivalent circuit. Note that the magnitude of the amplitude in the equivalent circuit represents the magnitude of the resistance for convenience.

FIG. 11 is a schematic diagram of a structure of a heat generating layer according to the present invention;
A is the base meandering pattern, B is the pattern after integration,
C is a diagram of the equivalent circuit. Note that the magnitude of the amplitude in the equivalent circuit represents the magnitude of the resistance for convenience.

FIG. 12 is a schematic view of a structure of a heat generating layer according to the present invention;
A is the base meandering pattern, B is the pattern after integration,
C is a diagram of the equivalent circuit. Note that the magnitude of the amplitude in the equivalent circuit represents the magnitude of the resistance for convenience.

FIG. 13 is a schematic view of a structure of a heat generating layer according to the present invention;
A is the base meandering pattern, B is the pattern after integration,
C is a diagram of the equivalent circuit. Note that the magnitude of the amplitude in the equivalent circuit represents the magnitude of the resistance for convenience.

FIG. 14 is a schematic diagram of a structure of a heat generating layer according to the present invention;
A is the base meandering pattern, B is the pattern after integration,
C is a diagram of the equivalent circuit. Note that the magnitude of the amplitude in the equivalent circuit represents the magnitude of the resistance for convenience.

FIG. 15 is a schematic view of a structure of a heat generating layer according to the present invention;
A is the base meandering pattern, B is the pattern after integration,
C is a diagram of the equivalent circuit. Note that the magnitude of the amplitude in the equivalent circuit represents the magnitude of the resistance for convenience.

FIG. 16 is a schematic view of a structure of a heat generating layer according to the present invention;
A is the base meandering pattern, B is the pattern after integration,
C is a diagram of the equivalent circuit. Note that the magnitude of the amplitude in the equivalent circuit represents the magnitude of the resistance for convenience.

FIG. 17 is a schematic view of a structure of a heat generating layer according to the present invention;
A is the base meandering pattern, B is the pattern after integration,
C is a diagram of the equivalent circuit. Note that the magnitude of the amplitude in the equivalent circuit represents the magnitude of the resistance for convenience.

FIG. 18 is a schematic cross-sectional view of a heat roller according to another embodiment of the present invention.

FIG. 19 is a diagram of the structure of a conventional heat generating layer.

FIG. 20 is a diagram of the structure of a conventional heat generating layer.

FIG. 21 is a schematic diagram around a fixing roller heating roller as an example of use of the heat generating roller according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixing roller 11 Release layer 12 Base 13 Insulating layer 14 Heat generation layer (resistance heating element) 15 Intermediate layer 21 Sponge rubber fixing roller 22 Heat generation roller 23 Paper passing direction 24 Paper 25 Pressure roller

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Katsuhiro Echigo 1-3-6 Nakamagome, Ota-ku, Tokyo Stock inside Ricoh Company (72) Inventor Jun Yura 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Inside the company Ricoh

Claims (16)

[Claims] An exothermic layer is formed by electrically connecting a plurality of exothermic elements made of a substance having a PTC characteristic in parallel in at least a roller axial direction by a pattern arrangement in the same plane. roller. 2. A paper passing reference is located at one end of the roller, and the heat generating layer has a heating element located at least on a roller passing direction reference side and a sheet passing reference side in the roller axial direction. The heat generating roller according to claim 1. 3. The paper feeding reference is located substantially at the center of the roller, and the heating layer has a heating element located at least at the center and both ends in the roller axial direction.
The heat generating roller according to 1. 4. The heating roller according to claim 2, wherein the width of the heating element located immediately near the sheet passing reference position is substantially equal to a minimum sheet width that allows continuous sheet passing. 5. The heat generating roller according to claim 1, wherein the heat generating density of the heat generating element located at the roller end is higher than the heat generating densities of the other heat generating elements. . 6. The heating element is a foil-shaped resistor having a meandering pattern, and the meandering patterns of the heating elements located adjacent to each other in the roller axis direction have the same pitch and the meandering directions are opposite. The heating elements are electrically connected in parallel in the roller axial direction by integrating the meandering patterns with each other at the meandering top.
The heat generating roller according to any one of claims 1 to 5, wherein 7. The heat generating roller according to claim 6, wherein a direction connecting a start point and an end point of the meandering pattern is substantially a roller circumferential direction. 8. The heat generating roller according to claim 7, wherein an integrated portion of the meandering pattern is located at a position substantially equal to an end passing position of a sheet that can be continuously passed. 9. The amplitude of the meandering pattern of the heating element located on the roller end side is smaller than the amplitude of the meandering pattern of the heating element located on the inner side of the roller.
The heat-generating roller according to any one of claims 1 to 8. 10. The pattern width of the meandering pattern of the heating element located on the roller end side is wider than that of the heating element located inside the heating element. The heat generating roller according to 1. 11. The heating layer is formed by a plurality of heating elements made of a foil-like NTC characteristic resistor having a meandering pattern, and a direction connecting a start point and an end point of the meandering pattern is substantially in a roller axial direction. And the meandering patterns of the heating elements located adjacent to each other in the roller circumferential direction have the same pitch and the meandering directions are opposite, and the meandering tops of those meandering patterns are integrated with each other. A heating roller characterized by the above. 12. The heat generating roller according to claim 11, wherein the meandering pattern has a narrower conduction path width at both ends of the roller than at a central portion of the roller. 13. The heat generating roller according to claim 11, wherein the meandering pattern has a narrower pitch at both ends of the roller than at the center of the roller. 14. The heating roller according to claim 6, wherein the heating element is made of stainless steel. 15. The heat generating roller according to claim 1, wherein the heat generating layer is disposed on an inner surface of the metal base with an insulating layer interposed therebetween. A heat generating roller, wherein a combination of materials is selected such that a difference in linear expansion coefficient is so small that a heat generating layer is not separated even if heating and cooling are repeated. 16. The metal substrate is made of aluminum,
The heat-generating roller according to claim 15, wherein the inner surface of the metal base is formed by an intermediate layer formed by winding a SUS foil one or more times around a tube and bonding or welding the SUS foil.