JPH1091025A - Heat roller, manuracture of it and fixing device using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the temperature of an offset preventive layer on an electrode layer from being extreamly lower than that of the offset preventive layer of an other part by transferring heat generated at a resistance heat generating layer which is not brought into contact with an electrode member in the direction of the center axis of a heat roller at the inside of a high heat conductive substrate. SOLUTION: This device is provided with a cylindrical high heat conductive substrate 12, the offset preventive layer 13 provided on the outer face of the substrate 12, an electrically insulated layer 11 provided on the inner face of the substrate 12 and the resistance heat generating layer 10 provided on the inner face of the layer 11. Also, plural ring-like high electrically conductive electrode members 14a and 14b splitting the heat generating area of the layer 10 in the axial direction of the substrate 12 are provided. Thus, in the case that the layer 10 is made to generate heat in a maximum heat generating area, the heat generated by the layer 10 that is not brought into contact with the members 14a and 14b is transferred in the direction of the center axis of the heat roller 1 at the inside of the substrate 12, so that the temperature of the layer 13 on the members 14a and 14b is prevented from being extreamly low.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat roller for fixing a toner on a toner support by heating and melting the toner on the toner support in a copying machine, a facsimile, a printer, and the like, and a method for manufacturing the same. And a fixing device using the heat roller.

[0002]

2. Description of the Related Art Conventionally, a fixing device using a heat roller in which a resistance heating layer is provided on the outer surface of an electrically insulating ceramic substrate and an offset preventing layer is further provided on the outer surface is disclosed in Japanese Patent Application Laid-Open No. 58-221875. Japanese Unexamined Patent Publication (Kokai) No. H10-264, pp. 157-334 is known. The purpose of the fixing device is to save energy by shortening the heating time, and to fix the toner on a plurality of toner supports having a width smaller than the length of the resistance heating layer continuously even if the toner is fixed on the toner support. An object of the present invention is to prevent an abnormal temperature rise of a heat roller in a non-contact portion.

FIG. 11 is a sectional view showing a heat roller in the prior art. Hereinafter, a conventional heat roller will be described with reference to FIG. As shown in FIG.
An insulating coating 10 is provided on both ends of the rotating shaft 101 made of metal.
5, conductive ring members 107 and 108 are fixed. The conductive ring members 107 and 108 are respectively connected to the journal members 102 and 103 via an electrically insulating member 106.
Is attached. Journal members 102, 103
Holds a cylindrical substrate 104 having electrical insulation. A plurality of holes are formed at both ends of the base 104. On the other hand, a plurality of projecting pieces are formed on the outermost peripheral portions of the journal members 102 and 103. Then, the protrusions of the journal members 102 and 103 are fitted into the holes of the base 4, thereby connecting the journal members 102 and 103 and the base 104. The base 104 is formed of ceramic having electrical insulation. This substrate 104
As the material, a material having heat resistance and small heat conductivity and heat capacity is desirable. On the outer surface of the base 104, a resistance heating layer 109 made of a metal such as nichrome or tungsten is provided.
Are formed. On the outer surface of the resistance heating layer 109, an anti-offset layer 110 made of polytetrafluoroethylene or silicone rubber is applied and formed. Inner surface of resistance heating layer 109 and journal members 102 and 103
Between the protruding pieces, strip-shaped electrode layers 111 and 112 made of copper or the like are formed so as to be in contact therewith. Band-shaped electrode layers 113 and 114 made of copper or the like are formed at predetermined intervals on the inner surface of the intermediate portion of the resistance heating layer 109 so as to be in contact with the resistance heating layer 109. The electrode layers 113 and 114 are connected to the conductive ring members 107 and 108 by conducting wires 115 made of copper or the like. The power supply brushes 116 and 117 are arranged so as to contact the outer peripheral surfaces of the journal members 102 and 103, and the power supply brushes 118 and 119 are arranged so as to contact the outer peripheral surfaces of the conductive ring members 107 and 108. I have. These power supply brushes 116 to 119 are connected to a power supply circuit 120. The power supply circuit 120 includes power supply brushes 116 and 117
Is applied to the entire range of the resistance heating layer 109 through the journal members 102 and 103 and the electrode layers 111 and 112, or the voltage is applied to the power supply brushes 118 and 119 to form the conductive ring member 107. , 108, the conductor 115, and the electrode layers 113 and 114, and power is supplied only to a predetermined range in the central portion of the resistance heating layer 109. The length of the resistance heating layer 109 is substantially the same as the width of the toner support having a large width, and the interval between the two electrode layers 113 and 114 is substantially the same as the width of the toner support having a small width. When fixing the support, power is supplied only to the portion between the electrode layers 113 and 114 of the resistance heating layer 109 by the power supply circuit 120. When fixing the toner support having a large width, the power supply circuit 120 supplies the power to the resistance heating layer. Power is supplied to the entire range of 109.

The resistance heating layer 109 generates Joule heat only in the portion where power is supplied, and the toner on the toner support contacting the offset prevention layer 110 is heated and melted by the heat generated by the resistance heating layer 109. The toner is fixed on the toner support.

[0005]

However, in the conventional heat roller as described above, even if an attempt is made to generate heat over the entire area of the resistance heating layer 109 in order to fix the toner on the toner support having a large width, the electrode is not heated. Since the resistance value of the layers 113 and 114 is extremely smaller than the resistance value of the resistance heating layer 109, most of the current flows through the electrode layers 113 and 114, and the resistance heating layer 109 on the electrode layers 113 and 114
Has almost no fever. As a result, the electrode layers 113 and 11
4, the temperature of the offset prevention layer 110 becomes extremely lower than the temperature of the offset prevention layer 110 in other portions. For this reason, the toner on the toner support at the positions of the electrode layers 113 and 114 is completely melted, the toner on the toner support does not fix to the toner support, or uneven fixing on the toner on the toner support occurs. There is a problem that it occurs.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems in the prior art, and when the resistance heating layer is caused to generate heat over its entire range, the temperature of the offset prevention layer on the electrode layer may be different from that of other parts. It is an object of the present invention to provide a heat roller that does not become extremely lower than the temperature of the offset prevention layer, a method for manufacturing the same, and a fixing device using the heat roller.

[0007]

Means for Solving the Problems To achieve the above object, a heat roller according to the present invention comprises a cylindrical substrate having high thermal conductivity, an offset prevention layer provided on an outer surface of the substrate, An electrical insulating layer provided on the inner surface of the base; a resistance heating layer provided on the inner surface of the electrical insulating layer; and a heating region of the resistance heating layer provided inside the resistance heating layer. A plurality of ring-shaped electrode members having high conductivity divided in a direction, a first power supply unit for supplying power to a maximum heat generation area of the resistance heating layer, and a second power supply unit for supplying power to the electrode members It is provided with. According to the configuration of the heat roller, when the resistance heat generation layer generates heat in the maximum heat generation region, heat generated in the resistance heat generation layer that is not in contact with the electrode member is transferred to the central axis of the heat roller in the high heat conductive base. To prevent the temperature of the offset prevention layer on the electrode member from becoming extremely lower than the temperature of the surrounding offset prevention layer. As a result, it is possible to solve the problems that the toner on the toner support does not fix to the toner support and that the toner on the toner support has uneven fixing.

Further, in the configuration of the heat roller of the present invention, the ratio t ₂ / t ₁ between the thickness t ₁ of the thickness t ₂ and the base electrode member is preferably 0.5 or less. According to this preferred example, even when the thickness of the substrate is reduced, the current flowing through the electrode member is reduced, and the current flowing through the resistance heating layer is increased, so that the temperature of the offset prevention layer on the electrode member is reduced by 5 ° C. Within.

In the heat roller according to the present invention, the ratio C ₂ / C ₁ of the heat capacity C _{2 of the} electrode member to the heat capacity C ₁ of the substrate in the width of the electrode member is 0.55 or less. Is preferred. According to this preferred example, even when the thickness of the base is reduced, the flow of heat to the electrode member can be reduced, and the temperature decrease of the offset prevention layer on the electrode member can be suppressed within 5 ° C. As a result, the rise time can be reduced.

Further, in the configuration of the heat roller of the present invention, the ratio W of the width W _{1 of the} electrode member to the thickness t _{1 of the} base is W.
₁ / t ₁ is preferably 10 or less. According to this preferred example, even when the thickness of the base member is reduced, the moving distance of the heat generated in the resistance heating layer not in contact with the electrode member to the base member on the electrode member is shortened, and the offset on the electrode member is reduced. The temperature decrease of the prevention layer can be suppressed within 5 ° C.
As a result, the rise time can be reduced.

In the heat roller according to the present invention, the resistance value of the resistance heating layer is set so that the power consumption of the resistance heating layer in the minimum divided area divided by the electrode member is always 1 kW or less. It is preferred that
According to this preferred example, generation of unnecessary radiation and noise can be suppressed, and adverse effects on other electric devices can be prevented.

Further, in the configuration of the heat roller of the present invention, it is preferable that the electrode member is provided on the inner surface of the resistance heating layer so as to be continuous without any gap in the circumferential direction of the resistance heating layer. According to this preferred example, when power is supplied to the electrode members, the resistance heating layer between the electrode members can be uniformly heated over the entire circumferential direction.

In the heat roller according to the present invention, the electrode member has a gap that is discontinuous in the circumferential direction of the resistance heating layer, and the width W _{2 of the} gap and the width of the base are different. the ratio W ₂ / t ₁ between the thickness t ₁ is is preferably 10 or less. According to this preferred example, even when an electrode member having a gap portion is used, the moving distance of heat generated in the resistance heating layer other than the resistance heating layer on the non-heating region to the base on the non-heating region is shortened. In addition, the temperature reduction of the offset prevention layer on the non-heat-generating region can be suppressed within 5 ° C.

In the heat roller according to the present invention, the electrode member has a gap portion that is discontinuous in a circumferential direction of the resistance heating layer, and the gap portion is formed of the resistance heating layer. At least one of parallel lines drawn parallel to the central axis of the resistance heating layer and both ends of the resistance heating layer from an end point of the electrode member inside the center axis direction does not include the end point. It is preferable that the shape is such that it intersects the edge of the electrode member. According to this preferred example, since the current can be made to flow uniformly from the electrode member, it is possible to prevent the generation of a non-heating region in the resistance heating layer.

In the heat roller according to the present invention, the second power supply means includes a plurality of electrodes having one end connected to the inner surface of the electrode member, and an electrode connected to the other end of the plurality of electrodes. It preferably comprises an axis. According to this preferred example, the power supply line to the electrode member can be easily drawn out. Further, in this case, it is preferable that the center of gravity of the shape connecting the connection portions of the electrodes and the electrode members passes through the central axis of the resistance heating layer. According to this preferred example, speed unevenness and vibration of the heat roller during rotation of the heat roller can be suppressed. In this case, it is preferable that the electrode and the electrode member are provided with means for restricting relative movement of the electrode and the electrode member in the circumferential direction of the resistance heating layer. According to this preferred example, it is possible to prevent the electrode and the electrode member from sliding in the circumferential direction of the resistance heating layer, thereby preventing sparking and poor contact between the electrode and the electrode member. When an electrode member having a gap portion is used, the electrode may slide and come into contact with the resistance heating layer in the gap portion, which may cause local high heat to be generated. Is done. In this case, it is preferable that the electrode and the electrode member are provided with means for restricting the relative movement of the electrode and the electrode member in the central axis direction of the resistance heating layer. According to this preferred example, the second
Can easily be positioned. In this case, it is preferable that the electrode is made of a material which is separated from and separated from the electrode member at a certain temperature or higher. According to this preferred example, it is possible to prevent the temperature of the resistance heating layer from reaching a certain temperature or higher. When an electrode member having a gap portion is used, the electrode may slide and come into contact with the resistance heating layer in the gap portion, which may cause local high-temperature heat generation. Will be resolved. In this case, it is preferable that the electrode member has a gap portion that is discontinuous in the circumferential direction of the resistance heating layer, and the electrode is connected to the electrode member other than the gap portion. According to this preferred example, the electrode does not come into contact with the resistance heating layer in the gap portion to generate local high heat. In this case, it is preferable that an electrode shaft supporting member having an electrical insulation property for supporting the electrode shaft is further provided. According to this preferred example, the electrode shaft can be stably supported. In this case, it is preferable that a cushion layer is further provided at a portion of the electrode shaft supporting member that comes into contact with the resistance heating layer. According to this preferred example, damage to the resistance heating layer when the electrode shaft support member is inserted inside the resistance heating layer is prevented. Further, in this case, it is preferable that the cushion layer be made of a material having electrical insulation. According to this preferred example, as the material of the electrode shaft support member, a metal material or the like can be used in addition to a resin or an inorganic material.
The range of material selection for the electrode shaft support member is expanded. In this case, it is preferable that the center of gravity of the electrode shaft support member passes through the center axis of the resistance heating layer. According to this preferred example, speed unevenness and vibration of the heat roller during rotation of the heat roller can be suppressed. In this case, it is preferable that the first power supply means is provided inside the resistance heating layer in a state where the electrode shaft is penetrated. According to this preferred example,
The power supply line to the electrode member can be easily pulled out in a state where the first power supply means is provided inside the resistance heating layer. In this case, it is preferable that an electrode support member having electrical insulation is interposed between the electrode shaft and the first power supply means. According to this preferred example, the first power supply unit and the second power supply unit are integrated, and the first and second power supply units can be stably fixed inside the resistance heating layer. In this case, it is preferable that a first power supply means supporting member having an electrical insulation property for supporting the first power supply means is further provided. According to this preferred example, the first power supply means can be fixed more stably.

Further, in the configuration of the heat roller of the present invention, it is preferable that the first and second power supply means are housed inside the resistance heating layer. According to this preferred example, when the heat roller is attached to the fixing device, the first and second power supply units are not carelessly touched.
Handling of the heat roller becomes easy.

Further, a first configuration of the method for manufacturing a heat roller according to the present invention comprises: a cylindrical base having high thermal conductivity;
An anti-offset layer provided on the outer surface of the base, an electrical insulating layer provided on the inner surface of the base, a resistance heating layer provided on the inner surface of the electrical insulation layer, and provided inside the resistance heating layer A plurality of ring-shaped electrode members having high conductivity for dividing a heating region of the resistance heating layer in the axial direction of the base; and a first power supply unit for supplying power to a maximum heating region of the resistance heating layer. A method for manufacturing a heat roller, comprising: a second power supply unit that supplies power to the electrode member, wherein the electrode member is made of an elastic body, and the outer diameter of the electrode member is set to be smaller than the inner diameter of the resistance heating layer. After the electrode member is inserted into the resistance heating layer in a state where the resistance is also reduced, the outer diameter of the electrode member is increased by elastic deformation, and the electrode member is mounted inside the resistance heating layer. And According to the first configuration of the method for manufacturing a heat roller, the electrode member is installed inside the heat roller without damaging the resistance heating layer between the end of the heat roller and the installation position of the electrode member. Can be.

Further, in the first configuration of the method for manufacturing a heat roller of the present invention, it is preferable to use an electrode member provided with a shrinking means for reducing the outer diameter. According to this preferred example, the electrode member can be easily inserted into the resistance heating layer without using a complicated jig. In addition, the conductive adhesive can be uniformly applied to the outer surface of the electrode member, and the electrode member can be inserted into the resistance heating layer without bringing the conductive adhesive into contact with the resistance heating layer.

In the first configuration of the method for manufacturing a heat roller according to the present invention, a conductive adhesive is applied to an outer surface of the electrode member, and the electrode member is mounted inside the resistance heating layer. Preferably, the conductive adhesive is dried or cured at a predetermined temperature to bond the electrode member and the resistance heating layer. According to this preferred example, even if there are gaps such as irregularities on the contact surface between the electrode member and the resistance heating layer, the conductive adhesive enters these gaps and fills the gaps. As a result, the current can flow more uniformly from the electrode member to the resistance heating layer, and the electrode member can be more firmly fixed to the inner surface of the resistance heating layer.

Further, a second configuration of the method for manufacturing a heat roller according to the present invention comprises: a cylindrical base having high thermal conductivity;
An anti-offset layer provided on the outer surface of the base, an electrical insulating layer provided on the inner surface of the base, a resistance heating layer provided on the inner surface of the electrical insulation layer, and provided inside the resistance heating layer A plurality of ring-shaped electrode members having high conductivity for dividing a heating region of the resistance heating layer in the axial direction of the base; and a first power supply unit for supplying power to a maximum heating region of the resistance heating layer. And a second power supply means for supplying power to the electrode member, wherein the second power supply means comprises a plurality of elastic bodies each having one end connected to an inner surface of the electrode member. And an electrode shaft connected to the other ends of the plurality of electrodes, and the second power supply means is connected to the resistance heating layer while the outer diameter of the electrode is smaller than the inner diameter of the electrode member. After being inserted inside, By increasing the pole profile, characterized by connecting the electrode to the electrode member. According to the second configuration of the method of manufacturing the heat roller, the second power supply unit can be connected to the electrode member without damaging the resistance heating layer.

Further, in the second configuration of the method for manufacturing a heat roller according to the present invention, after a curable conductive adhesive is applied to the electrodes and the electrodes are connected to the electrode members,
It is preferable that the conductive adhesive is cured at a predetermined temperature to bond the electrode and the electrode member. According to this preferred example, even if there are gaps such as irregularities on the contact surface between the electrode and the electrode member, the conductive adhesive enters these gaps and fills the gaps. As a result, a current can be more uniformly applied from the electrode to the electrode member, and the electrode can be more firmly fixed to the electrode member.

Further, a third configuration of the method for manufacturing a heat roller according to the present invention comprises a cylindrical base having high thermal conductivity,
An anti-offset layer provided on the outer surface of the base, an electrical insulating layer provided on the inner surface of the base, a resistance heating layer provided on the inner surface of the electrical insulation layer, and provided inside the resistance heating layer A plurality of ring-shaped electrode members having high conductivity for dividing a heating region of the resistance heating layer in the axial direction of the base; and a first power supply unit for supplying power to a maximum heating region of the resistance heating layer. And a second power supply means for supplying power to the electrode member, wherein the first power supply means penetrates through the second power supply means. Then, after being inserted into the resistance heating layer, an electrode support member having electrical insulation is interposed between the first power supply means and the second power supply means. . According to the third configuration of the method for manufacturing the heat roller, the first power supply unit and the second power supply unit are integrated, and the first and second power supply units are stably held inside the resistance heating layer. can do.

Further, in the third configuration of the method for manufacturing a heat roller according to the present invention, a hardening type conductive adhesive is applied to an outer surface of the first power supply means, and the first power supply means is provided. After being inserted into the resistance heating layer, the conductive adhesive is cured at a predetermined temperature, and the first power supply unit and the resistance heating layer are bonded to each other. After the cooling, the electrode supporting member is preferably interposed between the first power supply means and the second power supply means.
According to this preferred example, 2 is used as the material of the electrode support member.
Since a material having a heat resistance of 50 ° C. or less can be used, the range of material selection for the electrode support member is widened.

Further, the fixing device according to the present invention comprises a cylindrical base having high thermal conductivity, an offset preventing layer provided on the outer surface of the base, and an electric insulating layer provided on the inner surface of the base. A resistance heating layer provided on the inner surface of the electrical insulating layer, a power supply unit for supplying power to the resistance heating layer, a sliding contact provided in contact with the power supply unit,
A heat roller having power supply means connected to the sliding contact, and after rotating the heat roller to rub the power supply means and the sliding contact, controlling the power supply means to Control means for supplying power to the resistance heating layer. According to the configuration of the fixing device, before power is supplied from the power supply unit to the resistance heating layer, an electric insulator such as a toner and an oxide film adhered to a contact portion between the power supply unit and the sliding contact is removed. As a result, power can be stably supplied to the resistance heating layer through the sliding contact, and electrical noise and ignition due to sparks can be prevented.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described more specifically with reference to embodiments. (First Embodiment) FIG. 1 is a schematic configuration diagram showing a fixing device according to a first embodiment of the present invention, and FIG. 2 is a sectional view showing the configuration of the heat roller.

As shown in FIG. 1, a heat roller 1 for fixing toner on a toner support by heat and pressure.
Is held by the heat roller bearing 2. Here, the heat roller bearing 2 is made of a resin or a bearing having heat resistance and lubricity. A pressure roller 3 is in contact with the heat roller 1, thereby forming a nip width. Here, the pressing roller 3 includes a central shaft 3a made of a metal such as iron, and a heat-resistant elastic body 3b provided around the central shaft 3a. As the elastic body 3b, a heat-resistant rubber made of silicone, fluorine, or the like is used. To further improve the heat resistance, a copolymer of tetrafluoroethylene and perfluoroalkylvinyl ether (PF
A) is coated with a heat-resistant resin.

As shown in FIGS. 1 and 2, the large-diameter cylindrical portions of the first power supply means 6a and 6b having a large-diameter cylindrical portion and a small-diameter cylindrical portion are provided at both ends of the cylindrical resistance heating layer 10. It is inserted. On the central axis of the first power supply means 6a, a second power supply means 5a is provided while being supported by an electrode support member 9a inserted into the small-diameter cylindrical portion of the first power supply means 6a. A ring-shaped electrode member 14a is provided at an end of the second power supply means 5a located inside the resistance heating layer 10, and the outer surface of the electrode member 14a is
Is in contact with the inner surface of the A second power supply means 5b is provided on the central axis of the first power supply means 6b while being supported by an electrode support member 9b inserted into the small-diameter cylindrical portion of the first power supply means 6b. I have. A ring-shaped electrode member 14b is provided at an end of the second power supply means 5b located inside the resistance heating layer 10, and the outer surface of the electrode member 14b is in contact with the inner surface of the resistance heating layer 10. Has been. Sliding contacts 8a and 8b are in contact with the outer peripheral surfaces of the small-diameter cylindrical portions of the first power supply means 6a and 6b, respectively, and the sliding contacts 7a are on the outer peripheral surfaces of the second power supply means 5a and 5b. , 7b are in contact with each other. These sliding contacts 7a, 7b, 8a, 8b
Connected to each other.

The resistance heating layer 10 heats the heat roller 1 to melt the toner on the toner support. The resistance heating layer 10 is made of nichrome, tungsten, molybdenum, palladium silver, a mixed material of palladium silver and lead glass, or a combination of these materials, and has a thickness of about 5 to 20 μm.

The first power supply means 6a, 6b and the second power supply means 5a, 5b are made of copper, brass, brass having high conductivity,
It is made of metal such as copper alloy and silver alloy. Electrode members 14a, 1
Reference numeral 4b denotes a heat generating area of the resistance heat generating layer 10 which is a
It is for dividing in the axial direction of copper, high conductivity copper,
It is made of brass or an alloy material in which other metals such as silver and nickel are mixed. The thickness of the electrode members 14a and 14b is about 5 to 300 μm, and the width is about 0.1 to 10 mm. As a material of the electrode members 14a and 14b, a copper-based metal is particularly preferable.

The electrode supporting members 9a and 9b are electrically insulating,
It is made of a heat-resistant resin material having heat resistance and rigidity such as polyimide and polyphenylene sulfide, and an inorganic material such as glass and ceramics.

The sliding contacts 7a, 7b, 8a, 8b
And a material such as tough pitch copper, phosphor bronze, carbon, and silver alloy having abrasion resistance and high conductivity with the second power supply means 6a and 6b and the second power supply means 5a and 5b.

By adopting the above configuration,
Electric power can be supplied from the power supply means 4 to the maximum heat generation area of the resistance heating layer 10 via the sliding contacts 8a, 8b and the first power supply means 6a, 6b. Further, the electrode member 14a
And the distance between the electrode member 14b and a predetermined distance,
Power can be supplied from the power supply means 4 to the resistance heating layer 10 between the electrode members 14a, 14b via the sliding contacts 7a, 7b, the second power supply means 5a, 5b, and the electrode members 14a, 14b. Thus, heat can be generated in a predetermined region of the resistance heating layer 10 in the central axis direction.

A base 12 is provided on the outer surface of the resistance heating layer 10 via an electric insulating layer 11. On the outer surface of the base 12, an anti-offset layer 13 is applied and formed. The electric insulating layer 11 is for electrically insulating the resistance heating layer 10 from the base 12 and is made of a heat-resistant resin material such as polyimide or polyphenylene sulfide at 200 ° C. or higher, or an inorganic material such as glass or ceramic. The thickness of the electric insulating layer 11 is about 10 to 200 μm, preferably about 20 to 100 μm. As a material of the electric insulating layer 11, a material having a high thermal conductivity is preferable, and a polyimide resin is particularly preferable.

The base 12 is pressed by the pressure roller 3 to form a nip width. The base 12 is for conducting heat generated in the resistance heating layer 10 to the offset prevention layer 13. In this case, even if the heat generation amount of a part of the resistance heating layer 10 is small, the base 12 conducts the heat generated in the surrounding resistance heating layer 10 to the offset prevention layer 13. This prevents a temperature drop in the offset prevention layer 13 on the portion of the resistance heating layer 10. The base 12 is made of a material having high thermal conductivity and rigidity, specifically, iron, nickel, aluminum, copper, silver or a material having a thermal conductivity of 30 W / m · K or more or a combination thereof. As a material of the base 12, aluminum is particularly preferable. The outer diameter of the base 12 is about 8 to 60 mm, and the thickness is about 0.3 to 2.5 mm. From the viewpoint of reducing the rise time, the thickness of the base 12 is preferably less than 1.5 mm. The length of the base 12 may be any length as long as it is equal to or greater than the maximum width of the toner support to be used. In order to correspond to the A3 vertical size and to set the rise time to 20 seconds or less at 1 kW of power, in the case of the base 12 made of aluminum, the base 1
When the outer diameter of No. 2 is 35 mm or less, the thickness is 1.3 mm or less.

The offset preventing layer 13 is for directly contacting the toner, melting most of the toner, and melting and fixing the toner on the toner support. The anti-offset layer 13 has a heat resistance and a releasability from the toner, and has a high thermal conductivity, specifically, a fluororesin such as polytetrafluoroethylene (PTFE), PFA, and fluororubber; It is made of a silicone resin containing silicone rubber or the like, or a mixture of these materials with carbon. The thickness of the offset prevention layer 13 is about 10 to 500 μm.
The material of the offset prevention layer 13 is particularly preferably PTFE, and the thickness is preferably 5 to 50 μm.

Next, the operation of the fixing device having the above configuration will be described with reference to FIGS.
First, a small size (for example, A6 vertical to A4 vertical)
The case where the toner on the toner support is fixed to the toner support will be described.

The distance between the electrode member 14a and the electrode member 14b is set to be equal to or larger than the width of the small-sized toner support (in this case, 210 mm + 10 mm = 2).
20 mm). First, the sliding contact 7a from the power supply means 4,
Power is supplied only to 7b. Thereby, the sliding contacts 7a, 7b, the second power supply means 5a, 5b
And the electrode member 14a via the electrode member 14a, 14b,
Electric power is supplied to the resistance heating layer 10 between the electrode members 14b, and heat is generated in the resistance heating layer 10 between the electrode members 14a and 14b. When the temperature of the offset prevention layer 13 is a predetermined temperature (for example, 18
0 ° C.) until the electrode member 14
After power is supplied to the resistance heating layer 10 between a and b, the toner support passes between the heat roller 1 and the pressure roller 3. As a result, the toner on the toner support melts and is pressed to fix the toner on the toner support. When the toner support passes between the heat roller 1 and the pressure roller 3, the temperature of the offset prevention layer 13 is controlled to be constant (for example, 170 to 190 ° C.).

If the power consumption of the resistance heating layer 10 exceeds 1 kW, unnecessary radiation and noise are generated in large amounts, which adversely affects other electric equipment. For this reason, the resistance value of the resistance heating layer 10 is set so that the power consumption of the resistance heating layer 10 in the minimum divided region (here, the region between the electrode members 14a and 14b) is always 1 kW or less. Is preferred. Here, “always” means that the resistance value of the resistance heating layer 10 increases or decreases with an increase in temperature depending on the material used, but it means under any of these conditions. In addition, the influence of temperature or some gas is included in the meaning of “always”.

Next, a large size (for example, B4 vertical to A)
A case where the toner on the (3 vertical size) toner support is fixed to the toner support will be described. First power supply means 6
The distance between a and 6b is set to be greater than or equal to the width of the large-sized toner support (here, 290 mm +
10 mm = 300 mm). First, power is supplied from the power supply means 4 only to the sliding contacts 8a and 8b. This allows
Electric power is supplied from the power supply means 4 to the maximum heat generation area of the resistance heating layer 10 via the sliding contacts 8a and 8b and the first power supply means 6a and 6b, and heat is generated on the entire surface of the resistance heating layer 10. The subsequent operation is the same as the case where the toner on the small-sized toner support is fixed to the toner support, and therefore, the description is omitted. FIG. 3 is an enlarged sectional view near the electrode member. Since the electrode members 14a and 14b are made of a highly conductive material, the resistance heating layer 10 on the electrode members 14a and 14b
In the vicinity, most of the current (alternating current) 15 flows through the electrode members 14 a and 14 b, and almost no current 15 flows through the resistance heating layer 10. As a result, the electrode members 14a, 14
Heat is hardly generated in the resistance heating layer 10 on the electrode member 14b, and the temperature of the offset prevention layer 13 on the electrode members 14a and 14b may be extremely lower than the temperature of the surrounding offset prevention layer 13. For this reason, the toner on the toner support at the positions of the electrode members 14a and 14b is not completely melted, and the toner on the toner support does not fix to the toner support or uneven fixation on the toner on the toner support. Problem.

Therefore, in the present embodiment, the base 1
By using a material having high thermal conductivity for the electrode member 2,
The heat generated in the resistance heating layer 10 that is not in contact with 4a and 14b is moved in the base 12 in the direction of the central axis of the heat roller 1 (arrow 16 in FIG. 3). Accordingly, it is possible to prevent the temperature of the offset prevention layer 13 on the electrode members 14a and 14b from becoming extremely lower than the temperature of the surrounding offset prevention layer 13.

In order to shorten the rise time, the substrate 12
It is desirable to reduce the thickness of the substrate. However, when the thickness of the base 12 is reduced, the amount of heat transfer in the base 12 is reduced, so that the heat generated in the resistance heating layer 10 that is not in contact with the electrode members 14a, 14b is transferred to the base 12 on the electrode members 14a, 14b. To the electrode member 14a,
The temperature of the offset prevention layer 13 on 14b will decrease.

Therefore, in the present embodiment, the thickness of the electrode members 14a, 14b is reduced, and the thickness of the electrode members 14a, 14b is reduced.
4b, the current flowing through the electrode member 1 is reduced.
By increasing the current flowing through the resistance heating layer 10 on the electrode members 14a, 14b, the offset prevention layer 1 on the electrode members 14a, 14b is increased.
A study was conducted to prevent the temperature drop of No. 3. As a result, the electrode member 14a, the ratio t ₂ / t ₁ between the thickness t ₁ of 14b thickness t ₂ and the substrate 12 of the by 0.5 or less, even when the thickness of the substrate 12, the electrode member 14
a, 14b to reduce the current flowing through
0, the current flowing through the electrode members 14a, 14b
It has been found that the temperature decrease of the above-described offset prevention layer 13 can be suppressed within 5 ° C.

When the thickness of the base 12 is reduced in order to shorten the rise time, the ratio C ₂ / of the heat capacity C ₂ of the electrode members 14 a and 14 b to the heat capacity C ₁ of the base 12 in the width of the electrode members 14 a and 14 b is obtained. C ₁ becomes large, heat is deprived to the electrode members 14a, 14b, and the electrode members 14a, 14b
The temperature of the offset prevention layer 13 on 14b will decrease.

Therefore, in the present embodiment, by reducing the heat capacity of the electrode members 14a, 14b, the flow of heat to the electrode members 14a, 14b is reduced, and the offset prevention layer on the electrode members 14a, 14b is reduced. A study was conducted to prevent the 13 temperature drop. As a result, the electrode members 14a, 14b of the heat capacity C ₂ and the electrode member 14a, 14b
By setting the ratio C ₂ / C ₁ to the heat capacity C ₁ of the base 12 within the range of 0.55 or less, the flow of heat to the electrode members 14 a and 14 b can be reduced even when the thickness of the base 12 is reduced. As a result, it has been found that the temperature reduction of the offset prevention layer 13 on the electrode members 14a and 14b can be suppressed within 5 ° C.

When the thickness of the substrate 12 is reduced in order to shorten the rise time, the amount of heat transfer in the substrate 12 is reduced, so that the heat generated in the resistance heating layer 10 not in contact with the electrode members 14a and 14b. Heat is applied to the electrode members 14a, 14
b, it is difficult to move the substrate 12 to the substrate 12, and the temperature of the offset prevention layer 13 on the electrode members 14a, 14b decreases.

Therefore, in the present embodiment, by reducing the width of the electrode members 14a, 14b, the heat generated in the resistance heating layer 10 that is not in contact with the electrode members 14a, 14b is formed on the electrode members 14a, 14b. A study was conducted to prevent the temperature of the offset prevention layer 13 on the electrode members 14a and 14b from lowering by shortening the moving distance of the offset prevention layer 13 on the electrode members 14a and 14b. As a result, by setting the ratio W ₁ / t ₁ of the width W ₁ of the electrode members 14 a and 14 b to the thickness t _{1 of the} base 12 to 10 or less, even when the thickness of the base 12 is reduced, the electrode members 14 a and 14 b By moving the heat generated in the resistance heating layer 10 that is not in contact with the electrode member 14a, 14b to the base 12 on the electrode members 14a, 14b, the temperature of the offset prevention layer 13 on the electrode members 14a, 14b is reduced by 5 ° C. or less. I found that it can be suppressed.

In this embodiment, a pair of electrode members (electrode members 14a, 14a) are provided inside heat roller 1.
Although the case where b) is provided has been described as an example, the present invention is not necessarily limited to this configuration, and more pairs of electrode members are provided inside the heat roller 1 according to the size of the toner support. You may.

Further, in the present embodiment, the case where the sliding contacts 7a, 7b are respectively brought into contact with the outer peripheral surfaces of the second power supply means 5a, 5b has been described as an example, but it is not necessarily limited to this configuration. The sliding contacts 7a, 7
b may be configured to directly contact the electrode members 14a and 14b.

In this embodiment, the case where the resistance heating layer 10 is provided on the entire inner surface of the heat roller 1 has been described as an example. However, the present invention is not necessarily limited to this configuration. By partially removing the resistance heating layer along the circumferential direction of the heat roller 1,
The resistance value of the resistance heating layer may be adjusted. Also, so that the temperature of both ends of the heat roller 1 becomes high,
The resistance heating layer may have a resistance value distribution. (Second Embodiment) The configuration of the heat roller according to the present embodiment is different from the configuration of the heat roller according to the first embodiment in that the electrode member is made of a plate-like elastic material. is there.

FIG. 4 is a perspective view showing an electrode member according to the second embodiment of the present invention, and FIG. 5 is a cross-sectional view showing a method of installing the electrode member inside the heat roller according to the second embodiment of the present invention. FIG.

As shown in FIG. 4A, the electrode member 40
a and 40b are made of a spring material made of a metal material such as copper or brass, and are formed in a plate shape having a width of 0.1 to 10 mm and a thickness of 5 to 300 μm.

In FIG. 5, reference numeral 17 denotes an electrode member installation means. The electrode member installation means 17 is for holding the electrode member 40b and installing the electrode member 40b inside the heat roller 1. The electrode member installation means 17 is a cylindrical rigid body made of resin, metal, or the like, and its outer diameter is smaller than the inner diameter of the resistance heating layer 10. Also, electrode member installation means 1
At the tip of 7, a step portion for holding the electrode member 40b is provided. In FIG. 5, reference numeral 18 denotes an electrode member pushing means. The electrode member pushing means 18 is made of resin,
It is a columnar rigid body made of metal or the like, and is inserted into the electrode member installation means 17. Then, the electrode member pushing means 18 is inserted into the electrode member placing means 17, and the electrode member pushing means 1 is fixed while the electrode member pushing means 18 is fixed.
7 is moved rearward (in the direction of the arrow in FIG. 5B), the electrode member 4 held at the tip of the electrode member installation means 17 is moved.
0b can be pushed out from the electrode member installation means 17. In FIG. 5, reference numeral 19 denotes a heat roller schematic layer (electric insulating layer 1
1, a substrate 12, and an offset prevention layer 13).

The method for installing the electrode member inside the heat roller will be described below with reference to FIGS. 4, 5A, and 5B.
This will be described with reference to FIG. First, the plate-like electrode member 40b shown in FIG. 4A is bent into a ring shape as shown in FIG. 4B. Next, as shown in FIG. 5A, the outer diameter of the electrode member 40 b is made smaller than the inner diameter of the resistance heating layer 10, and the electrode member 40 b is held at the step at the tip of the electrode member installation means 17. Then, the electrode member pushing means 18 is inserted into the electrode member setting means 17. Then, FIG.
As shown in FIG. 5B, the electrode member setting means 17 is inserted to a predetermined position inside the resistance heating layer 10 and the electrode member setting means 17 is moved backward while the electrode member pushing means 18 is fixed (FIG. 5B). Arrow direction). This allows
Electrode member 40 held at the tip of electrode member installation means 17
The electrode b is extruded from the electrode member installation means 17, and the extruded electrode member 40 b is fixed to the inner surface of the resistance heating layer 10 by increasing its outer diameter due to elastic deformation.

As described above, in a state where the outer diameter of the electrode member 40b is smaller than the inner diameter of the resistance heating layer 10, the electrode member 4
0b is inserted to a predetermined position inside the resistance heating layer 10, and the outer diameter of the electrode member 40b is increased by elastic deformation so that the electrode member 40b is fixed to the inner surface of the resistance heating layer 10. 1 to the electrode member 40b
The electrode member 40b can be installed inside the heat roller 1 without damaging the resistance heating layer 10 up to the installation position.

Next, as shown in FIG. 4C, the electrode members 41a and 41b having the cylindrical contraction means 20 provided inside.
FIG. 5 shows a method of installing the heat roller 1 inside the heat roller 1.
This will be described with reference to FIG. Here, the contraction means 20
Is for reducing the outer diameter of the electrode members 41a and 41b. In FIG. 5C, reference numeral 42 denotes an electrode member installation means. The electrode member installation means 42 is a simple one in which two linear rigid bodies made of metal or the like are rotatably supported at the center, and the tip ends thereof are electrode members 41a, 4a.
1b, and inserted into the shrinking means 20 so that the electrode members 41a, 41
The outer diameter of b can be reduced.

As shown in FIG. 5 (c), first, the tip of the electrode member installation means 42 is inserted into the contraction means 20 of the electrode members 41a, 41b, and then conductive adhesive is applied to the outer surfaces of the electrode members 41a, 41b. Apply the agent evenly. Then, FIG.
As shown by the solid line arrow in FIG.
Is compressed so that the outer diameter of the electrode members 41a and 41b is once smaller than the inner diameter of the resistance heating layer 10, and the electrode members 41a and 41b are
To a predetermined position inside the. Next, the electrode member 4
1a, 41b to the electrode member setting means 42
Remove. As a result, the outer diameters of the electrode members 41a and 41b increase due to elastic deformation (dotted arrows in FIG. 5C), and the outer surfaces of the electrode members 41a and 41b become the resistance heating layer 1.
Contact the inner surface of 0. Next, when the conductive adhesive is of a dry type, it is dried at a predetermined temperature, and when it is of a curable type, it is cured at a predetermined temperature and for a predetermined time.
1 a and 41 b are bonded and fixed to the inner surface of the resistance heating layer 10.

As described above, the contraction means 20 for reducing the outer diameter of the electrode members 41a and 41b is provided, so that the electrode members 41a and 41b can be used without using a complicated jig.
41b can be easily inserted inside the resistance heating layer 10. In addition, the electrode members 41 a and 41 b having the outer surface uniformly coated with the conductive adhesive can be inserted into the resistance heating layer 10 without bringing the conductive adhesive into contact with the resistance heating layer 10. Further, since the electrode members 41a and 41b are bonded and fixed to the inner surface of the resistance heating layer 10 using a conductive adhesive, gaps such as irregularities are formed on the contact surface between the electrode members 41a and 41b and the resistance heating layer 10. Even so, the conductive adhesive enters these gaps and fills the gaps. As a result, a current can be made to flow more uniformly from the electrode members 41 a and 41 b to the resistance heating layer 10, and the electrode members 41 a and 41 b can be more firmly fixed to the inner surface of the resistance heating layer 10.

When an electrode member having a length equal to the inner circumference of the resistance heating layer 10 is used, when the electrode member is installed inside the heat roller 1, both ends of the electrode member come into contact with each other, and the electrode member becomes resistant. The heating layer 10 is fixed to the inner surface of the resistance heating layer 10 in a continuous state without any gap in the circumferential direction. As a result, when power is supplied to the electrode members, the resistance heating layer 1
It is possible to uniformly generate heat at zero in all circumferential directions.

Next, a case where the electrode member provided inside the heat roller has a gap portion that is discontinuous in the circumferential direction of the resistance heating layer 10 will be described with reference to FIG. .

As shown in FIG. 6A, the heat roller 1
A pair of electrode members 43a and 43b are installed in a state in which the electrode members 43a and 43b are in contact with the inner surface of the resistance heating layer 10. Electrode members 43a, 43b has a gap portion 21, the width of the gap portion 21 is W _2. In FIG. 6A, reference numeral 19 denotes a heat roller schematic layer (the electrical insulating layer 11, the base 12, and the offset prevention layer 13) in which the configuration of the heat roller 1 other than the resistance heating layer 10 is summarized. Electrode members 43a, 43
When electric power is supplied to b to cause the resistance heating layer 10 between the electrode members 43a and 43b to generate heat, no current flows from the gap portion 21 and a non-heating region indicated by 22 is generated. For this reason, there is a possibility that the temperature of the offset prevention layer 13 on the non-heat-generating region 22 may decrease.

Therefore, in this embodiment, the gap portion
Width W of minute 21_TwoIs reduced, the non-heating area 2
2 occurred in the resistance heating layer 10 other than the resistance heating layer 10
The movement distance of the heat to the base 12 on the non-heat-generating region 22 is shortened.
Therefore, the temperature of the offset prevention layer 13 on the non-heat-generating region 22 is low.
A study was conducted to prevent lowering. As a result, the electrode member
The width W of the gap portion 21 between 43a and 43b_TwoAnd the thickness of the substrate 12
Mi t₁And the ratio W_Two/ T ₁Is set to 10 or less,
The electrode members 43a and 43b having the gap portions 21 are used.
Even in this case, the resistance other than the resistance heating layer 10 on the non-heating area 22
Substrate 1 on non-heat-generating region 22 of heat generated in anti-heat-generating layer 10
2 to reduce the offset on the non-heating area 22.
The temperature drop of the cut prevention layer 13 can be suppressed within 5 ° C.
I found that I could.

Next, the electrode member provided inside the heat roller has a gap portion that is discontinuous in the circumferential direction of the resistance heating layer, and the gap portion is formed in the center axis direction of the resistance heating layer. At least one of parallel lines drawn parallel to the central axis of the resistance heating layer and both ends of the resistance heating layer from an end point of the electrode member located inside intersects an edge of the electrode member not including the end point. For such a shape,
This will be described with reference to FIG.

As shown in FIG. 6B, the heat roller 1
A pair of electrode members 44a and 44b are installed in a state in which they are in contact with the inner surface of the resistance heating layer 10. The electrode members 44a and 44b have a gap portion 45. Edge 24 of electrode members 44a, 44b forming gap portion 45
Is not parallel to the central axis of the resistance heating layer 10. The electrode member 44 inside the central axis direction of the resistance heating layer 10
At least one of the parallel lines 25 drawn from the end points 23 a and 44 b toward both ends of the resistance heating layer 10 intersects the end sides 24 of the electrode members 44 a and 44 b not including the end point 23. In FIG. 6B, reference numeral 19 denotes the resistance heating layer 10.
Heat roller schematic layers (electric insulating layer 11, base 12, offset prevention layer 1)
3) is shown.

With the above configuration, power is supplied to the electrode members 44a and 44b, and the electrode members 44a and 44b are supplied.
When the resistance heating layer 10 between 4b is heated, the current from the electrode members 44a and 44b flows uniformly as indicated by an arrow 26 in FIG. 6B, thereby preventing the non-heating area from being generated in the resistance heating layer 10. be able to.

(Third Embodiment) FIG. 7 shows a third embodiment of the present invention.
FIG. 13 is a cross-sectional view illustrating a method of installing the second power supply unit in the heat roller according to the embodiment.

As shown in FIG. 7A, the heat roller 1
A ring-shaped electrode member 4 in contact with its inner surface.
6b is installed. Here, a projection 47 for fitting a fitting hole 32 of the electrode 30 described later is provided on the inner peripheral surface of the electrode member 46b. In FIG. 7, reference numeral 66 denotes a heat roller schematic layer (the resistance heating layer 10, the electric insulating layer 11, the base 12, and the offset prevention layer 13) in which the configuration of the heat roller 1 is put together. In FIG. 7A, reference numeral 28 denotes an electrode installation means. The electrode installation means 28 is for holding the second power supply means 5 and for installing the second power supply means 5 inside the heat roller 1. Electrode installation means 28
Is a cylindrical rigid body made of resin, metal, or the like, and its outer diameter is smaller than the inner diameter of the electrode member 46b. The second power supply means 5 is made of an elastic spring material,
8 to press the second power supply means 5 to the electrode installation means 2.
A pair of electrodes 30 also having a function of holding in the
It comprises a fitting hole 32 provided at the tip of the electrode 30, and an electrode shaft 31 extending along the central axis of the heat roller 1 from the connection between the pair of electrodes 30. Electrode 3
As the material of No. 0, a highly conductive shape memory alloy itself or a material obtained by laminating a shape memory alloy with a metal such as copper is used. The material of the electrode 30 may be a metal such as copper, phosphor bronze, or brass. The fitting hole 32 is fitted to the projection 47 on the inner peripheral surface of the electrode member 46b, thereby performing alignment of the second power supply means 5 and, at the same time, connecting the electrode member 46b and the electrode 30 to the circumference of the heat roller 1. It does not slide in the direction. Here, the fitting hole 32 is used as the sliding prevention means, but the present invention is not necessarily limited to this configuration. For example, a groove provided in parallel with the center axis direction of the heat roller 1 may be used. Further, the fitting hole 32 is used as the positioning means of the second power supply means 5, but the present invention is not necessarily limited to this configuration. For example, the fitting hole 32 is provided perpendicular to the recess or the center axis direction of the heat roller 1. It may be a groove or the like. FIG. 7 (a)
Reference numeral 29 denotes an electrode pushing means. The electrode pushing means 29 is a columnar rigid body made of resin, metal, or the like, and is inserted into the electrode setting means 28. Then, by inserting the electrode pushing means 29 into the electrode setting means 28 and moving the electrode setting means 28 backward (in the direction of the arrow in FIG. 7A) with the electrode pushing means 29 fixed,
The second power supply means 5 held inside the electrode installation means 28 can be pushed out from the electrode installation means 28. In FIG. 7C, reference numeral 33 denotes a disk-shaped electrode shaft support member made of an inorganic material such as resin, glass, or ceramics having electrical insulation, heat resistance, and rigidity. The electrode shaft support member 33 has a hole at its center. The electrode shaft support member 33 is inserted inside the resistance heating layer
The electrode shaft 31 of the second power supply unit 5 is supported in the central axis direction of the resistance heating layer 10 by inserting the electrode shaft 31 of the power supply unit 5 into the hole of the electrode shaft support member 33. FIG.
In (c), reference numeral 34 denotes a cushion layer made of a silicone sponge or the like having electrical insulation and heat resistance.
The cushion layer 34 is provided on the outer surface of the electrode shaft supporting member 33, thereby preventing the resistance heating layer 10 from being damaged when the electrode shaft supporting member 33 is inserted into the inside of the resistance heating layer 10. Since the cushion layer 34 is electrically insulating, the material of the electrode shaft support member 33 provided with the cushion layer 34 may be a metal material or the like in addition to the above-described materials. The range of choices expands.

Hereinafter, a method for connecting the second power supply means to the electrode member will be described with reference to FIG. FIG.
First, as shown in FIG.
8 (that is, a pair of electrodes 30).
In a state in which the outer diameter is reduced), the second power supply means 5 is held in the electrode installation means 28, and the electrode pushing means 29 is inserted into the electrode installation means 28. Next, the electrode installation means 28 is inserted into the resistance heating layer 10 until the projection 47 of the electrode member 46b and the fitting hole 32 of the electrode 30 are fitted. Next, the electrode setting means 28 is moved backward (in the direction of the arrow in FIG. 7A) while the electrode pushing means 29 is fixed. Thereby, the second power supply means 5 held inside the electrode setting means 28 is pushed out from the electrode setting means 28. The second extruded from the electrode installation means 28
The outer diameter of the pair of electrodes 30 of the power supply means 5 increases due to elastic deformation, and the fitting hole 32 of the electrode 30 fits into the projection 47 of the electrode member 46b. Thereby, the second power supply means 5 is connected to the electrode member 46b. Next, the electrode setting means 28 and the electrode pushing means 29 are connected to the resistance heating layer 1.
0 (FIG. 7B).

As described above, with the outer diameter of the pair of electrodes 30 reduced, the second power supply means 5 is inserted into the heat roller 1, and then the outer diameter of the pair of electrodes 30 is increased. Since the second power supply means 5 is fixed to the electrode member 46b, the second power supply means 5 can be connected to the electrode member 46b without damaging the resistance heating layer 10. Also, by fitting the projection 47 of the electrode member 46b with the fitting hole 32 of the electrode 30, the electrode member 46b
Since the electrode 30 and the electrode 30 do not slide in the circumferential direction of the heat roller 1, sparks and poor contact between the electrode member 46b and the electrode 30 can be prevented. In addition, since the electrode 30 is formed of a highly conductive shape memory alloy itself or a material in which a shape memory alloy is bonded to a metal such as copper,
When the temperature exceeds a certain temperature, the outer diameter of the pair of electrodes 30 becomes small, and the electrodes 30 and the electrode members 46b are separated from each other. Thereby, it is possible to prevent the resistance heating layer 10 from reaching a certain temperature or higher. When an electrode member having a gap portion is used, the electrode 30 may slide and come into contact with the resistance heating layer 10 in the gap portion, and local high heat may be generated in that portion. Is also eliminated.

FIG. 9 is a side view of the heat roller when the second power supply member is mounted on the electrode member, as viewed from the center axis direction of the heat roller. As shown in FIG. 9, in the electrode member 46 b having the gap portion 48, the protrusion 47 is provided other than the gap portion 21. For this reason, since the electrode 30 does not contact the gap portion 21, the electrode 30 does not come into contact with the resistance heating layer 10 in the gap portion 21 to generate local high heat.

The dotted lines in FIGS. 9B and 9C are lines connecting the contact portions between the electrode 30 and the electrode member 46b. The position of the electrode 30 to which the electrode shaft 31 is attached is
It is preferable that the center of gravity formed by connecting the contact portions of the heat roller 1 and the electrode member 46b passes through the central axis of the heat roller 1. According to this configuration, speed unevenness and vibration of the heat roller 1 during rotation of the heat roller 1 can be suppressed.

Next, as shown in FIG. 7C, the electrode shaft support member 33 provided with the cushion layer 34 is inserted into the heat roller 1, and the electrode shaft 31 of the second power supply means 5 is supported by the electrode shaft. It is inserted through the hole at the center of the member 33. Thus, the electrode shaft 31 of the second power supply means 5 is supported in the direction of the center axis of the heat roller 1, and the second power supply means 5 is stably held inside the heat roller 1.

Here, a disk-shaped electrode shaft support member 33 is used, but the electrode shaft support member 33 is not necessarily limited to this shape. For example, FIGS.
As in the case of the electrode 30 shown in (c), a plurality of plate-shaped electrodes extending in the direction of the resistance heating layer 10 from the center may be used. The center of gravity of the electrode shaft support member 33 is the heat roller 1
It is desirable to pass through the central axis of. According to this configuration, speed unevenness and vibration of the heat roller 1 during rotation of the heat roller 1 can be suppressed.

FIG. 8 is a sectional view showing a method for installing the first power supply means inside the heat roller according to the third embodiment of the present invention. As shown in FIG.
A ring-shaped electrode member 4 in contact with its inner surface.
6b is installed. Here, a projection 47 is provided on the inner peripheral surface of the electrode member 46b. Second power supply means 5
Is constituted by a pair of electrodes 30, a fitting hole 32 provided at a tip end of the electrode 30, and an electrode shaft 31 extending from a connecting portion of the pair of electrodes 30 along the central axis of the heat roller 1. I have. Then, the projection 47 of the electrode member 46 b is fitted into the fitting hole 32 of the electrode 30, and the second
Is attached to the electrode member 46b.
A disk-shaped electrode shaft support member 33 having a hole at the center is inserted into the heat roller 1, and the electrode shaft 31 of the second power supply unit 5 is inserted into the hole of the electrode shaft support member 33. As a result, the electrode shaft 31 of the second power supply means 5 is supported in the central axis direction of the heat roller 1. In FIG.
Reference numeral 6 denotes first power supply means. The first power supply means 6 is formed in a disk shape. A projection 49 is provided at the center of the first power supply means 6, and the projection 49 has a through hole 50.
Are formed. In FIG. 8, reference numeral 35 denotes a disk-shaped first power supply means supporting member made of an inorganic material such as resin, glass, or ceramics having electrical insulation, heat resistance, and rigidity. The first power supply means support member 35 has a hole at its center. Then, the first power supply means support member 35 is inserted into the heat roller 1, and the protrusion 49 of the first power supply means 6 is inserted into the hole of the first power supply means support member 35, The first power supply means 6 is stably supported. In FIG. 8, reference numeral 51 denotes an electrode support member. The electrode support member 51 is made of a heat-resistant resin material having electrical insulation, heat resistance, and rigidity such as polyimide or polyphenylene sulfide, or an inorganic material such as glass or ceramics, and is filled in the through hole 50 of the first power supply unit 6. Thus, the electrode shaft 31 of the second power supply means 5 is supported.

Hereinafter, a method of installing the first power supply means inside the heat roller will be described with reference to FIG. First, as shown in FIG. 8A, a first power supply unit 6 having a curable conductive adhesive (for example, a mixture of a polyimide resin and a metal) applied to the outer surface is connected to the inside of the heat roller 1. Into the through-hole 50 of the first feeding means 6.
Through the electrode shaft 31 of the second power supply means 5.

Next, as shown in FIG. 8B, the second power supply means support member 35 is inserted into the heat roller 1. As a result, the projection 49 of the first power supply means 6 is inserted through the hole of the first power supply means support member 35, and the first power supply means 6 is stably held inside the heat roller 1. Next, at a predetermined temperature (for example, 400 ° C. in the case of a conductive adhesive obtained by mixing a metal with a polyimide resin), the conductive adhesive applied to the outer surface of the first power supply unit 6 is cured, The first power supply means 6 is adhered to the resistance heating layer 10, and the first power supply means 6 is cooled to 250 ° C. or less.

Next, as shown in FIG. 8C, a space between the electrode shaft 31 of the second power supply means 5 and the first power supply means 6 is filled with the electrode support member 51, and the electrode shaft 31 is connected to the electrode. It is supported by the support member 51. Thereby, the first power supply means 6
And the second power supply means 5 are integrated, and the first and second power supply means 6 and 5 are stably fixed inside the heat roller 1. After the first power supply means 6 is cooled to 250 ° C. or less, the electrode support member 51 is filled between the electrode shaft 31 and the first power supply means 6.
A material having a heat resistance of 250 ° C. or less can be used, and the range of material selection for the electrode support member 51 is widened. Further, as shown in FIG. 8C, when the first power supply means 6 and the second power supply means 5 are provided so as not to protrude outside the heat roller 1, when the heat roller 1 is attached to the fixing device. The first power supply means 6 and the second power supply means 5 are not inadvertently touched.
Is easier to handle.

In this embodiment, the conductive adhesive is not applied to the electrode 30. However, the conductive adhesive is applied to the electrode 30 so that the electrode 30 is bonded to the electrode members 46a and 46b. You may.

(Fourth Embodiment) FIG. 10 is a flowchart showing a control method by control means of a fixing device according to a fourth embodiment of the present invention.

The operation of the fixing device will be described below with reference to FIGS. 1, 2, and 10. First, when the main power is turned on (S1), the heat roller drive motor provided on the heat roller 1 rotates (S2), and the heat roller 1 rotates (S3). When the heat roller 1 rotates, the first power supply means 6a, 6b and the sliding contacts 8a, 8b
In addition, the second power supply means 5a, 5b and the sliding contacts 7a, 7b are rubbed. Thereby, the contact portions between the first power supply means 6a, 6b and the sliding contacts 8a, 8b and the second power supply means 5
The toner and oxide film adhering to the contact portions between the sliding contacts a and 5b and the sliding contacts 7a and 7b are removed. Next, electric power is supplied from the power supply means 4 to the resistance heating layer 10 (S4) to cause the resistance heating layer 10 to generate heat. In this case, the power supply means 4
Before the power is supplied to the resistance heating layer 10 from the contact portions between the first power supply means 6a, 6b and the sliding contacts 8a, 8b and between the second power supply means 5a, 5b and the sliding contacts 7a, 7b. Since the electrical insulator such as toner and oxide film attached to the contact portion has been removed, the sliding contacts 7a, 7b, 8a, 8
Through b, electric power can be stably supplied to the resistance heating layer 10 and electric noise and ignition due to spark can be prevented.

As described above, the heat roller 1 is rotated to rub the first power supply means 6a, 6b with the sliding contacts 8a, 8b and the second power supply means 5a, 5b with the sliding contacts 7a, 7b. Then, by using the control means for supplying power to the resistance heating layer 10, power can be stably supplied to the resistance heating layer 10 and the sliding contacts 7a, 7b, 8
The generation of sparks a and 8b can be prevented.

[0081]

As described above, according to the present invention,
The heat roller includes a cylindrical high heat conductive base, an offset prevention layer provided on the outer surface of the base, an electric insulating layer provided on the inner surface of the base, and a resistance heating provided on the inner surface of the electric insulating layer. Layer and a plurality of ring-shaped highly conductive electrode members that divide the heating region of the resistance heating layer in the axial direction of the base, so that the resistance heating layer generates heat in the maximum heating region. In this case, the heat generated in the resistance heating layer that is not in contact with the electrode member is moved in the direction of the central axis of the heat roller in the high thermal conductive base, so that the temperature of the offset prevention layer on the electrode member becomes other than that. Extremely lower than the temperature of the offset prevention layer can be prevented.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating a fixing device according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a configuration of a heat roller of the fixing device according to the first embodiment of the present invention.

FIG. 3 is an enlarged cross-sectional view around an electrode member according to the first embodiment of the present invention.

FIG. 4 is a perspective view showing an electrode member according to a second embodiment of the present invention.

FIG. 5 is a cross-sectional view illustrating a method for installing an electrode member inside a heat roller according to a second embodiment of the present invention.

FIG. 6 is a cross-sectional view of a heat roller equipped with an electrode member having a gap according to a second embodiment of the present invention.

FIG. 7 is a cross-sectional view illustrating a method for installing a second power supply unit inside a heat roller according to a third embodiment of the present invention.

FIG. 8 is a cross-sectional view showing a method of installing the first power supply means inside a heat roller according to a third embodiment of the present invention.

FIG. 9 is a side view of a heat roller when a second power supply member is mounted on an electrode member according to a third embodiment of the present invention, as viewed from the central axis direction of the heat roller.

FIG. 10 is a flowchart illustrating a control method by a control unit of a fixing device according to a fourth embodiment of the present invention.

FIG. 11 is a cross-sectional view illustrating a heat roller according to the related art.

DESCRIPTION OF SYMBOLS 1 Heat roller 2 Heat roller bearing 3 Pressure roller 4 Power supply means 5a, 5b Second power supply means 6a, 6b First power supply means 7a, 7b, 8a, 8b Sliding contact 9a, 9b Electrode Supporting member 10 Resistance heating layer 11 Electrical insulating layer 12 Base 13 Offset prevention layer 14a, 14b Electrode member 17 Electrode member installation means 18 Electrode member pushing means 19 Heat roller schematic layer 20 Shrinking means 21 Gap portion 22 Non-heating area 23 End point 24 End Side 25 Parallel line 28 Electrode setting means 29 Electrode pushing means 30 Electrode 31 Electrode shaft 32 Fitting hole 33 Electrode shaft support member 34 Cushion layer 35 First power supply means support member

Claims (30)

[Claims] 1. A cylindrical base having a high thermal conductivity, an offset prevention layer provided on an outer surface of the base, an electric insulating layer provided on an inner surface of the base, and an inner surface of the electric insulating layer. A plurality of ring-shaped electrode members having high conductivity provided inside the resistance heating layer and dividing a heating region of the resistance heating layer in an axial direction of the base; and the resistance heating layer. A first power supply unit for supplying electric power to the maximum heat generation region of the first electrode, and a second power supply unit for supplying electric power to the electrode member.
A heat roller comprising: 2. The heat roller according to claim ₁ , wherein a ratio t ₂ / t ₁ of the thickness t _{2 of the} electrode member to the thickness t ₁ of the base is 0.5 or less. 3. The ratio C ₂ / C ₁ of the heat capacity C _{2 of the} electrode member to the heat capacity C ₁ of the substrate in the width of the electrode member is 0.5.
The heat roller according to claim 1, wherein the number is 5 or less. 4. The heat roller according to claim ₁ , wherein the ratio W ₁ / t ₁ of the width W _{1 of the} electrode member to the thickness t _{1 of the} base is 10 or less. 5. The heat roller according to claim 1, wherein the resistance value of the resistance heating layer is set such that the power consumption of the resistance heating layer in the minimum divided area divided by the electrode member is always 1 kW or less. . 6. The heat roller according to claim 1, wherein the electrode member is provided on the inner surface of the resistance heating layer so as to be continuous with no gap in the circumferential direction of the resistance heating layer. 7. The electrode member has a gap portion that is discontinuous in the circumferential direction of the resistance heating layer, and has a width W of the gap portion.
The heat roller according to claim 1 ₂ and the ratio W ₂ / t ₁ between the thickness t ₁ of the base is 10 or less. 8. The electrode, wherein the electrode member has a gap portion that is discontinuous in a circumferential direction of the resistance heating layer, and the gap portion is inside the center axis direction of the resistance heating layer. A shape in which at least one of parallel lines drawn from an end point of the member and parallel to a central axis of the resistance heating layer and both ends of the resistance heating layer intersects an edge of the electrode member not including the end point. The heat roller according to claim 1, wherein 9. The heat source according to claim 1, wherein the second power supply means includes a plurality of electrodes each having one end connected to the inner surface of the electrode member, and an electrode shaft connected to the other ends of the plurality of electrodes. roller. 10. The heat roller according to claim 9, wherein the center of gravity formed by connecting the connection portions of the electrode and the electrode member passes through the center axis of the resistance heating layer. 11. The heat roller according to claim 9, wherein the electrode and the electrode member are provided with means for restricting relative movement of the electrode and the electrode member in a circumferential direction of the resistance heating layer. 12. The heat roller according to claim 9, wherein the electrode and the electrode member are provided with means for restricting a relative movement of the electrode and the electrode member in a central axis direction of the resistance heating layer. 13. The heat roller according to claim 9, wherein the electrode is made of a material that comes into contact with and separates from the electrode member at a certain temperature or higher. 14. The electrode member according to claim 9, wherein the electrode member has a gap portion that is discontinuous in a circumferential direction of the resistance heating layer, and the electrode is connected to the electrode member other than the gap portion. Heat roller. 15. The heat roller according to claim 9, further comprising an electrode shaft supporting member having an electrical insulation property for supporting the electrode shaft. 16. The heat roller according to claim 15, wherein a cushion layer is provided at a portion of the electrode shaft supporting member that contacts the resistance heating layer. 17. The heat roller according to claim 16, wherein the cushion layer is made of a material having electrical insulation. 18. The heat roller according to claim 15, wherein the center of gravity of the electrode shaft supporting member passes through the center axis of the resistance heating layer. 19. The heat roller according to claim 9, wherein the first power supply means is provided inside the resistance heating layer while penetrating the electrode shaft. 20. An electrode supporting member having electrical insulation is interposed between the electrode shaft and the first power supply means.
10. The heat roller according to 9. 21. The heat roller according to claim 19, further comprising a first power supply means support member having an electrical insulation property for supporting the first power supply means. 22. The heat roller according to claim 1, wherein the first and second power supply means are accommodated inside the resistance heating layer. 23. A cylindrical substrate having high thermal conductivity, an offset preventing layer provided on an outer surface of the substrate, an electric insulating layer provided on an inner surface of the substrate, and an inner surface of the electric insulating layer. A plurality of ring-shaped electrode members having high conductivity provided inside the resistance heating layer and dividing a heating region of the resistance heating layer in an axial direction of the base; and the resistance heating layer. A method for manufacturing a heat roller, comprising: a first power supply unit for supplying power to the maximum heat generating region of the first embodiment; and a second power supply unit for supplying power to the electrode member, wherein the electrode member is made of an elastic body. After inserting the electrode member into the resistance heating layer in a state where the outer diameter of the electrode member is smaller than the inner diameter of the resistance heating layer, the outer diameter of the electrode member is increased by elastic deformation to increase the electrode diameter. The member of the resistance heating layer A method for manufacturing a heat roller, wherein the heat roller is fixed inside. 24. The method for manufacturing a heat roller according to claim 23, wherein an electrode member provided with shrinking means for reducing the outer shape is used. 25. A method in which a conductive adhesive is applied to an outer surface of the electrode member, and the electrode member is mounted inside the resistance heating layer, and then the conductive adhesive is dried or cured at a predetermined temperature. The method for manufacturing a heat roller according to claim 23, wherein the electrode member and the resistance heating layer are bonded to each other. 26. A cylindrical base having high thermal conductivity, an offset prevention layer provided on an outer surface of the base, an electrical insulating layer provided on an inner surface of the base, and provided on an inner surface of the electrical insulating layer. A plurality of ring-shaped electrode members having high conductivity provided inside the resistance heating layer and dividing a heating region of the resistance heating layer in an axial direction of the base; and the resistance heating layer. A method of manufacturing a heat roller, comprising: a first power supply unit that supplies power to a maximum heat generation area of the heat roller; and a second power supply unit that supplies power to the electrode member, wherein the second power supply unit includes: One end includes a plurality of electrodes made of an elastic body connected to the inner surface of the electrode member, and an electrode shaft connected to the other end of the plurality of electrodes, and the outer diameter of the electrode is smaller than the inner diameter of the electrode member. The second
A method of manufacturing a heat roller, comprising: inserting the power supply means into the resistance heating layer, and then increasing the outer shape of the electrode by elastic deformation to connect the electrode to the electrode member. 27. A method in which a curable conductive adhesive is applied to an electrode, and the electrode is connected to the electrode member. Then, the conductive adhesive is cured at a predetermined temperature to form the electrode and the electrode member. 27. The method of manufacturing a heat roller according to claim 26, wherein 28. A cylindrical substrate having high thermal conductivity, an anti-offset layer provided on an outer surface of the substrate, an electrical insulating layer provided on an inner surface of the substrate, and provided on an inner surface of the electrical insulating layer. A plurality of ring-shaped electrode members having high conductivity provided inside the resistance heating layer and dividing a heating region of the resistance heating layer in an axial direction of the base; and the resistance heating layer. A method of manufacturing a heat roller, comprising: a first power supply unit that supplies electric power to a maximum heat generating region of the heat roller; and a second power supply unit that supplies electric power to the electrode member, wherein the first power supply unit includes: After the first power supply means is inserted into the resistance heating layer so as to penetrate the second power supply means, an electric insulating property is provided between the first power supply means and the second power supply means. Characterized by interposing an electrode support member having Method of manufacturing a heat roller. 29. A curable conductive adhesive is applied to the outer surface of the first power supply means, and after inserting the first power supply means into the inside of the resistance heating layer, the conductive adhesive is applied to a predetermined position. The first power supply means and the resistance heating layer are adhered to each other, and the first power supply means is cooled to 250 ° C. or lower, and then the first power supply means and the second power supply The method for manufacturing a heat roller according to claim 28, wherein an electrode support member is interposed between the heat roller and the means. 30. A cylindrical base having high thermal conductivity, an offset prevention layer provided on an outer surface of the base, an electrical insulating layer provided on an inner surface of the base, and provided on an inner surface of the electrical insulating layer. And a power supply means for supplying power to the resistance heat generation layer, a sliding contact provided in contact with the power supply means, and a power supply means connected to the sliding contact. A fixing device comprising: a heat roller; and a control unit that controls the power supply unit to supply power to the resistance heating layer after the heat roller is rotated to rub the power supply unit and the sliding contact. apparatus.