JP2006259724A - Heating roller and fixing device - Google Patents

Abstract

To provide a heating roller and a fixing device capable of reducing deterioration due to thermal fatigue and suppressing deterioration in performance of a heating member that secures a certain nip width between the pressure member and the pressure member.
A shaft core 1a, an elastic layer 1b formed around the shaft core 1a, a conductive layer 1e disposed outside the elastic layer 1b and containing metal particles, an elastic layer 1b and a conductive layer 1e, at least one impedance matching layer 11c, 12c, 13c.
[Selection] Figure 2

Description

  The present invention relates to a fixing device that is mounted on an image forming apparatus such as a copying machine or a printer and fixes a developer image on a sheet, and a heating roller that is mounted on the fixing device.

  An image forming apparatus using digital technology, such as an electronic copying machine, has a fixing device that fixes a developer image melted by heating to a sheet by applying pressure.

  The fixing device includes a heating member that melts a developer, for example, toner, and a pressure member that provides a predetermined pressure to the heating member. A predetermined region is provided in a contact area (nip portion) between the heating member and the pressure member. A contact width (nip width) is formed. On the paper passing through the nip portion, the developer image on the paper melted by the heat from the heating member is fixed by the pressure from the pressure member.

For example, as a method of heating a heating member using induction heating, a heating member having a conductive thin film on a roller-shaped outer peripheral surface is provided with a magnetic field generated from an exciting coil to cause an eddy current to flow and generate heat. Are known. In this case, in order to maintain rigidity, a thin metal film made of metal (for example, nickel) has been used as the conductive thin film.
JP 2002-93566 A

  However, a metal film made of metal is easily oxidized. For example, if a metal film of a heating member made of nickel is heated to 200 ° C. or more and further subjected to pressure from a pressure member, it deteriorates due to thermal fatigue, and over a long period of time. It is difficult to maintain the function. Further, when the heating is finished and the metal film is cooled, the metal film may be damaged by the heat history, and it is difficult to maintain the performance of the heating member for a long time.

  Conventionally, a heating member having a metal film made of a nickel layer formed by electroforming or plating is known. In this case, nickel is prone to thermal degradation around 200 ° C. and has great restrictions on use, problems related to the manufacturing method by plating, that is, increase in equipment and difficulty in managing the deposition thickness. There are environmental problems related to waste liquid.

  Therefore, a heating member having a conductive film that can solve these problems is required.

  The present invention is for solving the above-described problems, and its purpose is to reduce deterioration due to thermal fatigue, and to suppress a deterioration in performance of a heating member that secures a certain nip width between the pressure member and the pressure member. It is an object of the present invention to provide a heating roller and a fixing device that can be used.

  According to one aspect of the present invention, the heating roller includes a shaft core, an elastic layer formed around the shaft core, a conductive layer disposed outside the elastic layer and including metal particles, and the elastic layer. And at least one impedance matching layer disposed between the conductive layer and the conductive layer.

  According to another aspect of the present invention, there is provided a fixing device comprising: a shaft core; an elastic layer formed around the shaft core; a conductive layer disposed outside the elastic layer and including metal particles; A heating member comprising at least one impedance matching layer disposed between an elastic layer and the conductive layer, a pressure member in pressure contact with the heating member, and the conductive layer using induction heating And a heating mechanism for generating heat.

  The present invention can provide a heating roller and a fixing device that can reduce deterioration due to thermal fatigue and can suppress a decrease in performance of a heating member that secures a certain nip width between the pressure member and the pressure member.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows an example of a fixing device of the present invention.

  As shown in FIG. 1, the fixing device includes a heating member (heating roller) 1 that heats the toner T on the paper P, a pressure member (pressure roller) 2 that applies a predetermined pressure to the heating roller 1, and an application force. A pressure mechanism 3 that provides a predetermined pressure of the pressure roller 2 and a heating mechanism 5 that heats the outer peripheral surface of the heating roller 1 by induction heating are provided.

  The heating roller 1 includes a shaft member (shaft core) 1a, which is a shaft made of a material having rigidity (hardness) that does not deform with a predetermined pressure, and an elastic layer (first layer) arranged around the shaft member 1a. 1 elastic layer, foamed rubber layer) 1b, impedance matching layer 1c, heat resistant resin layer 1d, conductive layer 1e that is induction-heated by the heating mechanism 5, solid rubber layer (second elastic layer) 1f, and release layer 1g. Have. The lamination of the impedance matching layer 1c to the release layer 1g disposed outside the elastic layer 1b is hereinafter referred to as an outer layer portion 1H (see FIG. 2). The outer layer portion 1H is bonded to both end portions of the elastic layer 1b with, for example, a heat resistant adhesive.

  The pressure roller 2 includes a shaft member 2a, an elastic layer (for example, silicon rubber) 2b disposed outside the shaft member 2a, and a release layer (for example, fluorine rubber) 2c.

  The pressure mechanism (pressure providing mechanism) 3 presses the pressure roller 2 toward the heating roller 1 by a pressure spring 3b through a bearing member 3a connected to the shaft member 2a. Thus, a nip portion 4 having a certain width (nip width) in the conveyance direction of the paper P is formed at the contact portion between the heating roller 1 and the pressure roller 2.

  The heating roller 1 that is in contact with the pressure roller 2 while maintaining a certain nip width or more by the pressure from the pressure mechanism 3 is rotated in the direction of the arrow (CW) by a drive motor (not shown). The With the rotation of the heating roller 1, the pressure roller 2 is rotated in the arrow direction (CCW).

  Outside the heating roller 1, there is disposed a heating mechanism 5 including an exciting coil 5a that provides a predetermined magnetic field to the conductive layer 1e of the heating roller 1, and a magnetic core 5b that is disposed outside the exciting coil 5a. Yes. The number of windings of the exciting coil 5a can be reduced by providing the magnetic core 5b.

  When a high-frequency current having a predetermined frequency is provided from an excitation circuit (inverter circuit) not shown, the excitation coil 5a generates a predetermined magnetic field corresponding to this frequency. By providing this magnetic field, an eddy current flows in the conductive layer 1e, and the heating roller 1 generates heat due to Joule heat generated according to the resistance of the conductive layer 1e.

  The toner T melted by the heat from the heating roller 1 passes through the nip portion 4 between the heating roller 1 and the pressure roller 2 and the pressure roller 2 applies a predetermined pressure to the paper P to which the toner T adheres. By being added, it is fixed on the paper P.

  Here, each component of the heating roller 2 will be described in more detail.

  The conductive layer 1e is formed by uniformly applying a conductive paste to the solid rubber layer 1f serving as a base during formation and then sintering the conductive paste. This conductive paste is a resin paste mixed with any one metal particle (metal filler) among gold, silver, platinum, copper, aluminum, nickel, stainless steel, a composite material of aluminum and stainless steel, iron, tin, or the like. It has been done. The conductive layer 1e has a specific magnetic permeability and resistance value according to the thickness and the type of metal particles to be configured. The conductive layer 1e has a predetermined value corresponding to the frequency of the current flowing through the exciting coil 5a. A penetration depth current (eddy current) flows. Incidentally, when the thickness of the conductive layer 1e is thinner than the penetration depth, the magnetic field generated from the exciting coil 5a may heat the shaft member 1a to heat the inside of the heating roller 1, for example. Further, since a magnetic field that is not used for induction heating is generated, there is a problem that the loss occurs and the heat generation efficiency deteriorates. However, in order to reduce the penetration depth, the frequency must be increased. In a fixing device that uses a frequency within a predetermined range, the current supplied to the exciting coil 5a according to the penetration depth. It is difficult to freely set the frequency.

  The impedance matching layer 1c matches the impedance of the entire heat generation target that is induction-heated by the magnetic field from the excitation coil 5a so that the magnetic field generated from the excitation coil 5a is used as induction heating near the outer peripheral surface of the heating roller 1. To do. In the present embodiment, the impedance matching layer 1c is constituted by a conductive paste that is uniformly applied to the heat-resistant resin layer 1d that is a base during formation and then sintered. This conductive paste is a resin paste mixed with any one metal particle (metal filler) among gold, silver, platinum, copper, aluminum, nickel, stainless steel, a composite material of aluminum and stainless steel, iron, tin, or the like. It has been done.

  The elastic layer 1b is made of foamed rubber obtained by foaming silicon rubber or the like, for example. In addition, the elastic layer 1b may be provided with a plurality of vent holes penetrating in the axial direction so as to positively escape the air inside the heating roller 1 to the outside in order to prevent deformation of the heating roller 2 due to thermal expansion. Further, the vent hole may be a cutout from the outer peripheral surface toward the shaft member 1a, or may be a plurality of holes reaching the shaft member 1a from the outer peripheral surface. For the same purpose, the elastic layer 1b may be formed of continuous bubbles, and both ends of the conductive layer 1e may be formed with mesh-shaped or dot-shaped air holes. Furthermore, the elastic layer 1b may be formed in a shape having a different diameter in the axial direction, for example, a tapered shape, in order to form a gap between the elastic layer 1b and the conductive layer 1e (or the heat resistant resin layer 1d). . Further, it is preferable that the elastic layer 1b and the conductive layer 1e are bonded not on the entire surface but only on a predetermined portion.

  The heat resistant resin layer 1d is made of, for example, a heat resistant resin containing polyimide. The heat resistant resin layer 1d is disposed between the impedance matching layer 1c containing the conductive paste and the conductive layer 1e, and supplements the mechanical strength of the outer layer portion 1H of the heating roller 1.

  In the present embodiment, the heating roller 1 has a diameter of 40 mm, the pressure roller 2 has a diameter of 40 mm, the elastic layer 1b has a thickness of 5 mm, the conductive layer 1e has a thickness of 10 μm, and the solid rubber layer 1f has a thickness of 200 μm. The release layer 1g is formed to a thickness of 30 μm. The solid rubber layer 1f is made of heat-resistant silicon rubber and has a function of increasing the adhesion strength between the conductive layer 1e and the release layer 1g. The release layer 1g is made of fluororesin (PFA or PTFE (polytetrafluoride). Ethylene) or a mixture of PFA and PTFE).

  In the present embodiment, the laminate composed of the impedance matching layer 1c, the heat resistant resin layer 1d, the conductive layer 1e, the solid rubber layer 1f, and the release layer 1g (hereinafter referred to as conductive layer laminate) is the outer release layer 1g. The solid rubber layer 1f, the conductive layer 1e, the heat-resistant resin layer 1d, and the impedance matching layer 1c are sequentially laminated on a cylindrical core material serving as a base material, and then turned inside out. Therefore, as described above, the conductive layer 1e is composed of the solid rubber layer 1f, and the impedance matching layer 1c is formed by uniformly applying a conductive paste to the heat-resistant resin layer 1d and then sintering. Explained. However, the conductive layer lamination of the present invention is not limited to this, and a cylindrical core material serving as a base material in the order of the impedance matching layer 1c, the heat resistant resin layer 1d, the conductive layer 1e, the solid rubber layer 1f, and the release layer 1g. The structure formed by laminating may be used. That is, the conductive layer 1e may be formed by applying a conductive paste uniformly to the heat-resistant resin layer 1d serving as a base and then sintering it.

  As shown in FIG. 1, around the heating roller 1, a peeling blade 6 for peeling the paper P from the heating roller 1 in order of rotation from the nip portion of the heating roller 1 and the pressure roller 2, and heating A cleaning roller 8 for removing toner adhering to the roller 1 is disposed. Further, at a predetermined position in the longitudinal direction of the heating roller 1, a thermistor 9 for detecting the temperature in the vicinity of the peripheral surface of the heating roller 1, and detecting that the surface temperature of the heating roller 1 has risen to an abnormal temperature, are excited. A thermo stud 10 for cutting off the electric power supplied to the coil 5a is arranged.

  Around the pressure roller 2, a peeling blade 7 for peeling the paper P from the pressure roller 2 and a cleaning roller 11 for removing the toner adhering to the heating roller 1 are arranged.

  Note that a plurality of thermistors 9 and thermostats 10 may be provided in the longitudinal direction of the heating roller 1. Further, a plurality of peeling blades 6 and 7 may be provided if the paper P is difficult to peel off, and may not be provided if the paper P is easily peeled off.

  In the present embodiment, the exciting coil 5a has a shape in which an electric wire is wound around an imaginary axis, and is longer than at least the sheet passing area (area in contact with the sheet P) in the longitudinal direction of the heating roller 1. Have a length. The exciting coil 5a having such a shape can generate magnetic flux in a concentrated manner, and can locally heat the conductive layer 1c of the heating roller 1.

  In addition, as the electric wire of the exciting coil 5a, a litz wire in which a plurality of coated copper wires whose surfaces are insulated is bundled is used. By using a litz wire as the electric wire of the exciting coil 5a, a magnetic field can be generated effectively. In this embodiment, a litz wire in which 18 copper wires (polyamideimide copper wire) having a diameter of 0.3 mm, the surface of which is insulated with heat-resistant polyamideimide, is used. However, the present invention is not limited to this. For example, a litz wire in which 19 copper wires having a diameter of 0.5 mm are bundled can be used.

  In the present embodiment, the exciting coil 5a is supplied with a high-frequency current in a frequency range of 20 to 50 kHz from an inverter circuit (not shown), and the amount of heat generated from the heating roller 1 varies in a range of 300 to 1500 W. To do. The frequency of the current supplied from the inverter circuit (not shown) can be arbitrarily selected, and a predetermined frequency can be selectively used while avoiding a specific frequency (for example, 40 kH, 60 kH).

  As described above, the conductive layer 1e made of a conductive paste is superior in bending resistance compared to a metal film made of metal. Further, the heating roller 1 is reinforced with mechanical strength by the heat-resistant resin layer 1d and has excellent flexibility. For this reason, the heating roller 1 according to the present invention reduces the deterioration due to thermal fatigue and thermal history even in an environment where induction heating is performed by the heating mechanism 5 and pressure is applied by the pressure roller 2, and the performance is maintained for a longer time. be able to. Therefore, the nip width of the nip portion 4 can be secured to a certain level or more, and the life of the heating member can be extended.

  In the present embodiment, it has been described that the heat-resistant resin layer 1d is disposed between the elastic layer 1b and the conductive layer 1e. However, the present invention is not limited to this, and the conductive layer 1e and the solid rubber layer 1f. May be arranged between the two, or may be arranged in both of them. Moreover, as long as sufficient mechanical strength can be ensured, the heat resistant resin layer 1d may not be provided.

  Further, by using a conductive paste containing copper for the conductive layer 1e, it is easily affected by an oxide film, and it is possible to use chemical sintering by supplying a known copper ion.

  Further, when the fixing device of the present invention is mounted on an image forming apparatus capable of color copying, the solid rubber layer 1f and the release layer 1g are made of a material having higher thermal conductivity in order to increase the area of the nip portion 4. Composed.

(Second Embodiment)
Next, another embodiment of the present invention will be described with reference to FIG.

  As shown in FIG. 2, the heating roller 1 is disposed between the shaft member 1a, the elastic layer 1b, the plurality of impedance matching layers 11c, 12c, and 13c, and the plurality of impedance matching layers 11c, 12c, and 13c. A plurality of heat-resistant resin layers 200, a conductive layer 1e disposed outside the plurality of impedance matching layers 11c, 12c, and 13c, a solid rubber layer 1f, and a release layer 1g. In addition, the same code | symbol is attached | subjected to the component which has the same structure as FIG. 1, and the detailed description is abbreviate | omitted below.

  The plurality of impedance matching layers 11c, 12c, and 13c are conductive layers in the order of the first impedance matching layer 11c, the second impedance matching layer 12c, and the third impedance matching layer 13c between the elastic layer 1b and the conductive layer 1e. It is arranged from the side closer to 1e.

  In addition to the first to third impedance matching layers 11c, 12c, and 13c, the plurality of heat resistant resin layers 200 are further provided between the first impedance matching layer 11c and the conductive layer 1e, and the third impedance matching layer. They are respectively arranged between the layer 13c and the elastic layer 1b.

  As described above, the first to third impedance matching layers 11c, 12c, and 13c are provided from the exciting coil 5a so that the magnetic field generated from the exciting coil 5a is used as induction heating near the outer peripheral surface of the heating roller 1. The impedance of the heat generation target that is induction-heated by the magnetic field is matched. Here, the heat generation target is one that is supplied with a magnetic field from the exciting coil 5a, flows an eddy current, and is heated by induction heating, and is mainly the conductive layer 1e. The layers 11c, 12c, and 13c can also generate heat upon receiving a magnetic field from the exciting coil 5a.

  In the present embodiment, the first to third impedance matching layers 11c, 12c, 13c and the conductive layer 1e are each formed to a thickness of 10 μm.

  As described above, the heating roller 1 according to this embodiment includes the thin conductive layer 1e and the first to third impedance matching layers 11c, 12c, and 13c. The conductive layer 1e and the first to third impedance matching layers 11c, 12c, and 13c are each composed of a conductive paste. For this reason, high flexibility is shown and a nip width of a certain level or more can be secured at the nip portion 4. This is particularly beneficial when the fixing device according to the present embodiment is mounted on an image forming apparatus capable of color copying.

  Further, the heating roller 1 according to the present embodiment has a configuration in which each of the first to third impedance matching layers 11c, 12c, and 13c is sandwiched between heat resistant resin layers 200. For this reason, the mechanical strength is strong, and further, the conductive paste constituting the first to third impedance matching layers 11c, 12c, 13c and the conductive layer 1e has a property of being excellent in bending resistance. Excellent in flexibility.

  Accordingly, the heating roller 1 of the present invention is induction-heated by the heating mechanism 5 and the deterioration due to thermal fatigue and thermal history is reduced even in an environment where the pressure is applied by the pressure roller 2. For this reason, the performance of the heating roller 1 can be maintained for a longer time, and the nip width of the nip portion 4 can be secured to a certain level or more.

  The plurality of impedance matching layers 11c, 12c, and 13c can be adjusted in magnetic permeability and resistance value by changing the content of metal particles contained and the type of metal, and therefore are induction-heated by a magnetic field from the excitation coil 5a. The penetration depth of the heat generation target can be adjusted to a predetermined value. The first to third impedance matching layers 11c, 12c, and 13c are each formed to a predetermined thickness, or the number of the conductive layers 1e and the entire impedance matching layer is adjusted to generate heat corresponding to the exciting coil 5a. A thickness equivalent to the penetration depth of the target can be secured.

  For example, in the fixing device in which the frequency of the current supplied to the exciting coil 5a is limited to a low frequency (for example, 30 kHz or less), the thickness of the first to third impedance matching layers 11c, 12c, and 13c is increased. Alternatively, by increasing the number of the first to third impedance matching layers 11c, 12c, and 13c, it is possible to ensure the thickness of the entire heat generation target equivalent to the penetration depth. Incidentally, if only one layer of the heat generation target having a thickness corresponding to the penetration depth is formed, sufficient flexibility cannot be obtained, and it is difficult to secure a sufficient nip width.

  In this way, by adjusting the number, thickness, and permeability of the plurality of impedance matching layers 11c, 12c, and 13c, the heat generated by induction heating by the frequency of the current flowing through the exciting coil 5a and the magnetic field from the exciting coil 5a. The heat generation efficiency of the heating roller 1 can be improved by matching the penetration depth of the target.

  Similarly, by adjusting the number, thickness, and magnetic permeability of the plurality of impedance matching layers 11c, 12c, and 13c in accordance with the thickness, material, and magnetic permeability of the conductive layer 1e disposed outside these layers. Thus, the penetration depth of the heat generation target that is induction-heated by the magnetic field from the exciting coil 5a can be adjusted to a predetermined value more effectively. The conductive layer 1e is disposed outside the heating roller 1, that is, closer to the exciting coil 5a than the plurality of impedance matching layers 11c, 12c, and 13c. Therefore, it is required to generate a lot of Joule heat and increase the heat generation efficiency by induction heating.

  For example, when the conductive layer 1e and the plurality of impedance matching layers 11c, 12c, and 13c are formed of the same material, the thickness of the conductive layer 1e disposed on the outermost side is reduced, and the plurality of impedance matching layers 11c, It is preferable to make 12c and 13c thicker than the thickness of the conductive layer 1e. This is because the resistance is inversely proportional to the cross-sectional area, and the higher the resistance, the more eddy current flows and the heat generation efficiency becomes higher. It should be noted that by making the layer thickness thinner than the penetration depth, it is possible to forcibly increase the density of eddy currents and generate heat.

When the conductive layer 1e and the plurality of impedance matching layers 11c, 12c, and 13c are formed with the same thickness, the outermost conductive layer 1e has the highest magnetic permeability, and the plurality of impedance matching layers 11c. , 12c, and 13c are preferably made of a material having a magnetic permeability equal to or lower than that of the conductive layer 1e. For example, it is preferable to use nickel, silver, aluminum, or the like for the outermost conductive layer 1e. This is because the penetration depth decreases as the magnetic permeability increases, as shown in the penetration depth formula shown in the following formula 1. Here, δ is the penetration depth, ρ is the body resistivity, μ is the relative permeability of the conductor, and f is the current frequency.

... (Formula 1)
Furthermore, it is preferable to make the penetration depth outside the heating roller 1 smaller than the inside penetration depth, and the conductive layer 1e has the smallest penetration depth, and a plurality of impedances arranged on the inner side. It is preferable that the penetration depth of the matching layers 11c, 12c, and 13c is gradually increased. In this case, what is arranged on the outside may be a magnetic body, and what is arranged on the inside may be non-magnetic.

  Thus, by adjusting the parameters of the conductive layer 1e and the plurality of impedance matching layers 11c, 12c, and 13c, the heat generation efficiency of the conductive layer 1e can be maximized.

A silver paste may be used as the conductive layer 1e or the plurality of impedance matching layers 11c, 12c, and 13c. This silver paste is hardened by heating silver dissolved in a binder, and the binder remains. For this reason, the resistivity 2 × 10 ⁻⁶ Ωcm of the silver paste is more than 10 times larger than the resistivity 5 × 10 ⁻⁵ Ωcm of silver itself, and the heat generation efficiency by induction heating is high. Therefore, the silver paste is more preferably used for the conductive layer 1e.

  The rigidity (hardness) of the heating roller 1 can be adjusted by adjusting the number of conductive layers 1e and the first to third impedance matching layers 11c, 12c, and 13c and the film pressure. Therefore, since the nip width of the nip portion 4 formed between the pressure roller 2 and the pressure roller 2 can also be adjusted, for example, the first to third impedance matching layers 11c, 11c, Heating the paper P, increasing the number of 12c, 13c, lowering the hardness of the heating roller 2, increasing the nip width of the nip portion 4, increasing the passage speed of the paper P, and reducing the heating time of the paper P passing through Time control is possible.

  Although not shown, the first to third impedance matching layers 11c, 12c, and 13c may be electrically connected to both ends of the heating roller 1 in the axial direction. As a result, the thermal conductivity of both ends of the heating roller 1 is improved, and the thermal energy of the third impedance matching layer 13c inside the heating roller 1 is rapidly transferred toward the outer first impedance matching layer 11c. Can lead. Therefore, since both ends of the heating roller 1 are heated by the curved portions of the exciting coils 5a arranged to face each other, the conventional problem that the surface temperature of the heating roller 1 partially decreases is improved, and the heating roller 1 heat generation unevenness can be avoided.

(Third embodiment)
Next, another embodiment of the present invention will be described with reference to FIGS.

  As shown in FIGS. 3 and 4, the heating roller 1 has a crack 300 that divides at least the conductive layer 1 e. As shown in FIG. 3, the crack 300 may divide the conductive layer 1 e linearly in the axial direction of the heating roller 1, and as shown in FIG. 4, the outer peripheral surface of the heating roller 1 is spiral. The conductive layer 1e may be divided.

  Moreover, the crack 300 is formed in each of the 1st-3rd impedance matching layers 11c, 12c, and 13c, as shown in FIG. In this case, the crack 300 is formed at a position shifted by a predetermined angle in the thickness direction in each of the conductive layer 1e and the first to third impedance matching layers 11c, 12c, and 13c.

  Thereby, even when the conductive layer 1e is pushed up from the inner side by the thermally expanded elastic layer 1b, the conductive layer 1e spreads in the circumferential direction of the heating roller 1, so that an event in which the conductive layer 1e is cracked or wrinkled can be avoided. Further, the hardness of the heating roller 2 may be too high due to the difference in thermal expansion coefficient between the elastic member 1b and the conductive layer 1e, but this phenomenon can be prevented by spreading the conductive layer 1e in the circumferential direction. .

  Moreover, as shown in FIG. 6, the crack 300 formed in each of the conductive layer 1e and the first to third impedance matching layers 11c, 12c, and 13c is formed at a position where the phase differs in the circumferential direction of the heating roller 1. The crack 300 does not overlap in the thickness direction. For this reason, even if a temperature drop occurs in the crack 300, it is a slight temperature drop that occurs in any one of the thin-film conductive layer 1e and the first to third impedance matching layers 11c, 12c, and 13c. Is negligible. Therefore, an event in which the temperature of the outer peripheral surface of the heating roller 1 is locally reduced is avoided, and uneven heat generation on the outer peripheral surface of the heating roller 1 can be prevented.

  Further, the crack 300 is not formed in the solid rubber layer 1f and the release layer 1g formed outside the conductive layer 1e so that the surface in contact with the paper P does not become uneven. In addition, as described above, the conductive layer 1e formed of the conductive paste is softer than the conductive layer made of only metal and has excellent bending resistance. Therefore, even if the crack 300 as described above is formed. The outer peripheral surface of the heating roller 1 is hardly affected.

  The crack 100 may be formed by removing a predetermined region of the conductive layer 1e by etching or the like, or may be a simple cut. Further, as shown in FIG. 6, a part of the heat-resistant resin layer 200 may enter the crack 300, or a gap may be present.

(Fourth embodiment)
Next, another embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 6, the outer layer portion 1H (see FIG. 2) outside the elastic layer 1b including the conductive layer 1e has a plurality of vent holes 400 at both ends in the axial direction.

  The air hole 400 is formed in a non-sheet passing region at both end portions of the heating roller 1, and actively guides the air inside the conductive layer 1e to the outside. In the present embodiment, the air holes 400 are preferably formed in a general circle having a diameter of 1 mm.

  Therefore, even when the conductive layer 1b is heated and the inner air is thermally expanded, the inner air is guided to the outside by the vent hole 400, and the difference in thermal expansion coefficient between the elastic member 1b and the conductive layer 1e is caused. This can prevent an event in which the hardness of the heating roller 2 becomes too high. Further, a nip width of a certain level or more for obtaining a high-quality image can be secured in the sheet passing area.

  The outer layer portion 1H is bonded to a part of the outer peripheral surface of the elastic layer 1b disposed on the inner side with, for example, a heat-resistant adhesive so as not to crush the hole of the vent hole 400. In addition, it is preferable that the outer layer portion 1H and the central portion of the elastic layer 1b are non-bonded and a gap is formed therebetween.

  Further, as shown in FIG. 6, a plurality of ventilation holes 400 may be randomly formed. For example, as shown in FIG. 7, they may be formed side by side in the radial direction, as shown in FIG. The end portion may be formed in a mesh shape.

  The present invention is not limited to the above-described embodiments, and various modifications and changes can be made without departing from the scope of the invention when it is implemented. Moreover, each embodiment may be implemented in combination as appropriate as possible, and in that case, the effect of the combination can be obtained.

  For example, in the above embodiment, the heat-resistant resin layer 1d shown in FIG. 1 and the heat-resistant resin layer 200 shown in FIGS. 2 and 5 have been described as being made of a heat-resistant resin such as polyimide. However, the present invention is not limited thereto, and metal particles may be included for the same purpose as that of the impedance matching layer described above. In this case, the content of the contained metal particles is set so as to reinforce the mechanical strength.

  The elastic layer 1b may be solid rubber that is not foamed.

  Furthermore, the pressure roller 2 may have a configuration having an elastic layer, a reinforcing layer, and a conductive layer, like the heating roller 1.

  Furthermore, the elastic member 2b may be made of, for example, foamed rubber in which open cells are formed. In the elastic layer 1c, in which the end portion and the central portion are made of different members, at least the end portion is foamed with open cells. It is preferable that it is made of rubber. Further, as the foamed rubber, in addition to silicon rubber, a foamed polyimide can be used. Furthermore, as the elastic layer 1c, polyimide, polyamide, or polyamideimide material can be used.

1 is a schematic diagram illustrating an example of a fixing device to which an embodiment of the present invention can be applied. Sectional drawing for demonstrating an example of the heating member shown in FIG. Schematic which shows the other example of the heating member shown in FIG. Schematic which shows the example from which the heating member shown in FIG. 3 is further different. Sectional drawing which shows an example of the heating member shown to FIG. Sectional drawing for demonstrating the further different example of the heating member which can be utilized for the fixing apparatus shown in FIG. Schematic which shows the other example of the heating member shown in FIG. Schematic which shows the example from which the heating member shown in FIG. 6 is further different.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Heat roller, 1a ... Shaft member, 1b ... Elastic layer, 1c ... Impedance matching layer, 1d ... Heat-resistant resin layer, 1e ... Conductive layer, 1f ... Solid rubber Layer, 1 g ... release layer, 2 ... pressure roller, 3 ... pressure mechanism, 4 ... nip, 5 ... heating mechanism, 6 ... peeling blade, 7 ... * Peeling blade, 8 ... cleaning member, 9 ... thermistor, 10 ... thermostat.

Claims (11)

The shaft core,
An elastic layer formed around the axis;
A conductive layer disposed outside the elastic layer and containing metal particles;
A heating roller comprising at least one impedance matching layer disposed between the elastic layer and the conductive layer. The heating roller according to claim 1, wherein the conductive layer is made of a conductive paste in which metal particles are mixed with a resin paste. The heating roller according to claim 1, wherein the impedance matching layer is made of a conductive paste in which metal particles are mixed with a resin paste. 4. The metal particle according to claim 1, wherein the metal particles include at least one of gold, silver, copper, aluminum, nickel, stainless steel, a composite material of aluminum and stainless steel, iron, and tin. The heating roller as described. 5. A plurality of impedance layers are arranged between the elastic layer and the conductive layer, and a heat resistant resin layer is formed between the plurality of impedance layers. The heating roller according to any one of the above. 5. The heat-resistant resin layer is included in at least one of the elastic layer and the impedance matching layer and at least one of the impedance matching layer and the conductive layer according to claim 1. The heating roller as described. 7. The heating roller according to claim 1, wherein at least one of the impedance layer and the conductive layer has a split that is divided in an axial direction. The heating according to any one of claims 1 to 6, wherein at least one of the impedance layer and the conductive layer has a crack that is divided into line segments inclined at a predetermined angle with respect to an axial direction. roller. The heating roller according to any one of claims 1 to 8, wherein the conductive layer is thinner than at least one impedance layer. A shaft core, an elastic layer formed around the shaft core, a conductive layer disposed outside the elastic layer and including metal particles, and at least disposed between the elastic layer and the conductive layer A heating member comprising one impedance matching layer;
A pressure member in pressure contact with the heating member;
And a heating mechanism that heats the conductive layer using induction heating. The elastic layer has an outer diameter at both end portions in the axial direction larger than an outer diameter at the center portion, and has an air gap between the impedance matching layer and the impedance matching layer at the both end portions having a larger outer diameter. The fixing device according to claim 10, wherein the fixing device is connected to the fixing device.

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