JPH05188809A - Fixing device - Google Patents

Abstract

PURPOSE:To provide a fixing device whose structure is simple, which can be miniaturized as a whole and increases heat efficiency and keeps high reliability over a long period. CONSTITUTION:In the fixing device which forms an image by interposing and carrying a recording medium 13 on which the image of unfixed toner 20 is mounted between a heating means and a pressurizing means and fixing the image of the toner 20 on the medium 13, a heat generating roll integrally formed by mixing at least a heating element in a heat resistant and insulating resin substrate is used for the heating means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device, and more particularly to a fixing device.
The present invention relates to a fixing device suitable for, for example, a copying machine and an electrophotographic printer, which forms an image by fixing unfixed toner to a sheet-shaped transfer material or recording medium such as paper by applying pressure and heat.

[0002]

2. Description of the Related Art Generally, in an image forming apparatus such as an electronic copying apparatus, a fixing device for fixing an unfixed toner image on a recording medium such as a sheet to form an image has a heating means by a fixing roll and a fixing roll. 2. Description of the Related Art A fixing device provided with a pressure roll that comes into pressure contact with and rotates following is widely used for reasons such as its safety, high speed, and good thermal efficiency.

Hereinafter, such a general fixing device will be described with reference to FIGS. 12 to 15.

FIG. 12 is a perspective view showing a main part of a conventional fixing device, and FIG. 13 is a sectional view thereof.

As shown in detail in FIGS. 12 and 13, a conventional fixing device 1 includes a frame 4 having a flat base 2 having standing portions 3 and 3 which are bent upward in the vertical direction at both longitudinal ends thereof. A fixing roll 6 rotatably supported on the upright portions 3 and 3 of the frame 4 via bearings 5 and 5, and a pressure roll adapted to be driven to rotate by a predetermined pressing force on the fixing roll 6. 7 and 7.

To further explain, the fixing roll 6 is made of a metal such as aluminum, copper, iron or the like, or a non-ferrous metal or the like, and is formed into a substantially cylindrical hollow. A thin release layer 9 made of a fluororesin such as an alkoxyethylene copolymer or a material having a good releasability such as silicone rubber is formed by coating. Further, a rod-shaped halogen lamp 10 is arranged as a heating element in the mandrel 8 so that the surface of the fixing roll 6 can be heated to a desired temperature suitable for fixing. Further, a surface temperature of the fixing roll 6 is controlled by a temperature sensor (not shown) so as to be always a desired temperature. As a power supply means for the halogen lamp 10, both ends of the halogen lamp 10 are supported by fixed electrodes 11, 11 made of a conductive member provided outside the standing portions 3, 3 of the frame 4, and a power source (not shown) is provided. Power is supplied from. A driven gear 23, to which a driving force from a drive source (not shown) is transmitted, is fixed to a desired position at one end of the fixing roll 6 so that the fixing roll 6 can be rotated in a desired direction. There is.

Further, on the surface of the fixing roll 6, a recording medium 13 such as a paper is wound around the fixing roll 6 on a support column 12 which is horizontally attached and fixed at appropriate positions of the standing portions 3 and 3 of the frame 4. A desired number of separation claws 14 for preventing the above are abutted. Further, a cleaning device (not shown) for removing offset toner, paper dust, etc. is provided as necessary.

The pressure roll 7 is made of aluminum,
An outer peripheral surface of a mandrel 15 formed of a metal such as copper or iron or a non-ferrous metal having a circular cross section is covered with an elastic layer 16 made of silicone rubber or the like. Both ends of the pressure roll 7 are rotatably supported by support members 17 and 17 and one end of each of the support members 17 and 17 is located at an appropriate position of the standing portions 3 and 3 of the frame 4. And the other end is fastened to a desired position of the standing portions 3, 3 of the frame 4 via springs 18, 18 which are biasing members.

Further, the fixing roll 6 and the pressure roll 7 are configured to form a nip 19 by being brought into contact with each other with a desired force by the above-mentioned springs 18, 18.

The operation of the conventional fixing device 1 will be described. In the recording medium 13 such as a sheet on which the image of the unfixed toner 20 is transferred, the image of the unfixed toner 20 is made to face the fixing roll 6, and It is conveyed by an appropriate conveying means in the direction indicated by arrow A in the figure. The recording medium 13 onto which the image of the unfixed toner 20 is transferred is the fixing roll 6 and the pressure roll 7.
By being nipped and conveyed between the sheet and the sheet, the image of the unfixed toner 20 is fixed on the recording medium 13 by being pressed and heated.

Another example of the fixing roll 6 will be described with reference to FIGS. 14 and 15.

The fixing roll 6a shown in FIG. 14 will be described. The fixing roll 6a is made of a metal such as aluminum, copper, iron or the like, or a non-ferrous metal or the like, and is a cored bar 8 formed in a substantially cylindrical shape.
An insulating layer 21 is provided on the outer peripheral surface of a, a metal resistance layer 22 is formed on the outer peripheral surface of the insulating layer 21 by plating, sputtering, or the like, and polytetrafluoroethylene, tetrafluoroethylene- A thin release layer 9 made of a fluororesin such as fluoroalkoxyethylene copolymer is formed by coating. Then, power is supplied to the metal resistance layer 22 by an appropriate power supply device (not shown) to generate heat.

The fixing roll 6b shown in FIG. 15 will be described. The fixing roll 6b has a metal resistance which is divided into a plurality of pieces in the circumferential direction on the outer peripheral surface of a mandrel 8b which is formed of an insulating material such as glass or ceramics and has a substantially cylindrical shape. The layer 22 is formed, and the outer peripheral surface of the metal resistance layer 22 is further coated with a thin release layer 9 made of a fluororesin such as polytetrafluoroethylene or tetrafluoroethylene-fluoroalkoxyethylene copolymer. .. Then, power is supplied to the metal resistance layer 22 by an appropriate power supply device (not shown) to generate heat.

[0014]

However, in the fixing device 1 to which the fixing roll 6 formed so as to have the above-mentioned conventional halogen lamp 10 therein is applied, the surface temperature of the fixing roll 6 is always desired. Since the temperature is controlled by using the radiant heat of the halogen lamp 10 to reach the temperature, the thermal efficiency is poor, and the halogen lamp 1
The heat generated by 0 consumes a large amount of power, and there is a problem that the halogen lamp 10 of 600 W or more has to be used. Further, the halogen lamp 10 is attached to the fixing roll 6
Depending on the size of the halogen lamp 10, for example, the halogen lamp 10 has a diameter of 6 m.
There is a problem in that the size of the fixing roll 6 cannot be reduced to m or less, and the size of the fixing roll 6, in particular, the outer diameter dimension is restricted, and the fixing roll 6 cannot be reduced in diameter. Further, since the diameter of the fixing roll 6 cannot be reduced, the fixing device 1 cannot be made thin, and the space of the fixing device 1 occupying the entire device is increased, which is a serious problem in downsizing the entire device.

Further, as shown in FIG. 14, in the fixing roll 6a in which the metal resistance layer 22 is formed on the outer peripheral surface of the insulating layer 21 formed on the surface of the cored bar 8a by plating or sputtering, the size of the fixing roll 6a is large. In particular, although the outer diameter size can be reduced, since the material has a multi-layered structure, the thermal expansion of each material is different, and further, the fixing roll 6a repeats the temperature rise and the temperature decrease, and the internal stress causes metal resistance. There was a problem that the layer 22 peeled off.

Further, as shown in FIG. 15, in the fixing roll 6b in which the metal resistance layer 22 is formed on the outer peripheral surface of the mandrel 8b made of an insulator, the mandrel 8b made of an insulator such as ceramic and glass is manufactured. However, there is a problem that the processing cost is increased and the economical burden is increased.

The present invention has been made in view of these points, and overcomes the above-mentioned problems in the conventional ones.
It is an object of the present invention to provide a fixing device which has a simple structure and can be downsized as a whole, and which can increase thermal efficiency and maintain high reliability for a long period of time.

[0018]

In order to achieve the above-mentioned object, the fixing device of the present invention according to claim 1 is a recording medium having an unfixed toner image mounted between a heating means and a pressure means. In a fixing device that forms an image by sandwiching and conveying and fixing the unfixed toner image on the recording medium, the heating means is integrated by mixing at least a heating element in a resin substrate having heat resistance and insulation. It is characterized in that it is a heat-generating roll that is formed.

According to a second aspect of the present invention, in the fixing device, the recording medium having the unfixed toner image is sandwiched and conveyed between the heating means and the pressing means to convey the unfixed toner image. In a fixing device for forming an image by fixing on a recording medium, the heating means is made of a resin roll having heat resistance and insulation, and a heat generating layer made of a carbon-containing conductive material is provided on the surface of the base. It is characterized in that the heating roll is integrally formed.

[0020]

According to the fixing device of the present invention described in claim 1,
At least a metal heating element is mixed in the resin substrate to form a small-diameter heating roll that is easily integrally molded. Then, the heat energy can be directly transferred to the toner by the heat generating roll. Therefore, the thermal efficiency of the heating means can be improved.

As described in claim 2, by using the carbon-containing conductive material formed on the surface of the resin substrate as the heat generating layer, a heat generating roll having a small diameter is formed. Then, the heat energy can be directly transferred to the toner by the heat generating roll. Therefore, the thermal efficiency of the heating means can be improved.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS.

1 to 9 show a first embodiment of a fixing device according to the present invention.

As shown in FIG. 1, the fixing device 2 of the present embodiment.
Reference numeral 4 denotes an appropriate frame 27 having standing portions 26, 26 bent upward in the vertical direction at both ends in the longitudinal direction of a flat plate-shaped base 25, and bearings 28, 28 on the standing portions 26, 26 of the frame 27. The fixing roller 29 is rotatably supported by a small diameter fixing roller 29, and the fixing roller 29 is driven by a small pressing roller 30 with a predetermined pressing force as in the conventional case. The fixing roll 29 is a heat-generating roll which itself generates heat.

Further, the fixing roll 29 and the pressure roll 3
The diameter of 0 may be the same or different as long as it is small.

Explaining further, the fixing roll 29
As shown in FIGS. 2 and 3, is composed of a substantially cylindrical mixed-molded base 31 and a release layer 32 formed on the outer surface of the mixed-molded base 31, so that these are integrated. Has been formed. Further, as shown in FIG.
The axial length Lb of 2 is shorter than the axial length La of the fixing roll 29, and the mixing and molding base 31 is exposed at both ends of the fixing roll 29 in the axial direction with an appropriate length to receive power. The parts 33, 33 are formed. A driven gear 23 to which a driving force from a drive source (not shown) is transmitted is fixed to a desired position at one end of the fixing roll 29, and the fixing roll 29 is rotated in a desired direction as in the conventional case. It is designed to let you.

Further, as shown in FIG. 1, the power receiving unit 3
Electric power is supplied to the electric power supply means 3 and 33 by pressure contact electric power supply brushes 36 and 36 formed so that the carbon block 34 is always brought into contact with the electric power receiving portion by a proper pressing force by a spring 35. The press-contact power supply brushes 36, 36 are attached to an appropriate case 37 to be integrated and fixed to a desired frame (not shown), and are connected by a power source 38 and a wiring member 39.

The mixed molding base 31 is integrally molded by mixing a heating element with a resin material and molding.
The material of the resin applied to the mixed molding base 31 is a material having heat resistance and insulation, such as polyimide (P
I), polyamideimide (PAI), polyetherimide (PEI), polyetheretherketone (PEE)
K), polyphenylene sulfite (PPS), polyether sulfone (PES), poly-P-xylylene (P)
A material appropriately selected from engineering plastics such as PX) is formed into a solid roll shape with a diameter of 15 mm in this embodiment by a desired molding method such as injection molding. The diameter of the mixed-molded substrate 31 may be appropriately determined according to design specifications, and is not particularly limited to this embodiment.

A carbon filler was used as the heating element. The content of the heating element may be appropriately determined according to design specifications.
It is advisable to mix about 0 to 90% by volume. As the heating element, carbon beads, Ti, Ta, V,
Zr and their carbides or nitrides, Ni metal, N
It may be selected from various metal fine particles of metals such as i-Cr, Ni-P, and Ni-Cr-P alloy, and is not particularly limited to this example. Further, beads, various fillers, pigments, etc. may be mixed as a reinforcing material. Further, the particle size (average particle size) distribution, shape, etc. may be appropriately selected.

The release layer 32 is made of a material appropriately selected from fluororesins such as polytetrafluoroethylene (PTFE) and tetrafluoroethylene-fluoroalkoxyethylene copolymer, and is appropriately coated by electrostatic coating or the like. A film is formed on the mixed-molded substrate to a thickness of about 10 to 20 μm by a means, or by covering a tube-shaped member of the material. The thickness of the release layer 32 may be appropriately determined according to design specifications, and is not particularly limited to this embodiment. Further, as the material of the release layer 32, silicone rubber, fluorine rubber or the like may be used.

It is also possible to supply an appropriate release agent such as dimethyl silicone oil to the surface of the mixed molding substrate 31 without forming the release layer 32, and it is particularly limited to this embodiment. It is not something that will be done.

Further, a pressure roller 30 having a small diameter is brought into contact with the fixing roller 29 as a pressing means as in the conventional case.

Next, the operation of this embodiment having the above-mentioned structure will be described.

First, the recording medium 13 such as a sheet on which the image of the unfixed toner 20 is transferred is made to face the image of the unfixed toner 20 with the fixing roll 29 in the same manner as in the conventional case, and is carried by an appropriate conveying means (not shown). By being nipped and conveyed in the nip 19 formed by the fixing roll 29 and the pressure roll 30 which constitute the heating means, the image of the unfixed toner 20 is fixed on the recording medium 13 by being pressed and heated. It

As shown in FIG. 1, the method of feeding power to the fixing roll 29 is as follows. As shown in FIG. 1, the pressure-feeding brushes 36, 33 are pressed against the power receiving portions 33, 33 of the mixed molding base 31 formed at both ends of the fixing roll 29. Through 36. Further, electric power is supplied to the fixing roll 29 under the control of an appropriate sensor (not shown). Further, since the fixing roll 29 has a small diameter and is formed so as to generate heat by itself, the time required for raising the temperature to a desired temperature is short and the power consumption can be reduced. For example, the fixing roll 29 of the present embodiment is provided with a mixed molding substrate 31 in which a desired amount of a carbon filler having a specific resistance value of 4 × 10 ⁻³ Ωcm is mixed with a resin material, and the mixing molding substrate 31 has a resistance of 1.0 to 1.5 Ωcm. When the fixing roll 29 as a whole has a resistance value of 20 to 25Ω with a solid roll having a specific resistance and a heat generating portion length of 240 mm and a heat generating portion diameter of 15 mm, a voltage of 100 V which is a power source for household use. When the current is applied, the power consumption can be 500 W or less at the current I = 5 A or less. Further, the mixed molding base 31 of the fixing roll 29 integrally molded.
Since heat is generated by itself, unlike the conventional case, it is possible to avoid adverse effects such as peeling due to thermal expansion, and it is possible to speed up the heat transfer response to the toner and increase the thermal efficiency.

Further, the fixing device 24 of the present embodiment is supplied with power by the pressure contact supply brush 36 as a power supply means, so that the fixing device 24 is fixed at both ends of the conventional rod-shaped halogen lamp 10 by metal fiber brushes or metal plates. Unlike the power supply means to which the electrode 11 is applied, it is possible to prevent the occurrence of contact failure due to wear and arc consumption.

The shape of the fixing roll 29 may be a fixing pipe 29a having a hollow pipe shape as the mixed molding base 31, as shown in FIG. 4, and is not particularly limited to this embodiment.

As the power feeding means, various types as described below can be used.

First, as shown in FIG. 5, a substantially Y-shaped pressure contact feeding brush in which a conductive member such as a carbon block is in contact with the power receiving portions 33, 33 of the fixing roll 29 and the semicircular contact surface. It may be 36a.

Next, as shown in FIGS. 6 (a) to 6 (c), the metal power supply electrode 40, which is a cylindrical cap with a conductive member and has a bottom, is connected to the power receiving portions 33 at both ends of the fixing rolls 29, 29a. , 33 to be fixed so as to cover them, and through fixed electrodes 41, 41 made of a conductive member provided at appropriate positions outside the erected portions 26, 26 of the frame 27 as a power feeding means for feeding power from a power source (not shown). Good.

Further, as shown in FIGS. 7 (a) to 7 (c), a desired power supply ring 42, 4 made of a conductive material, for example, metal, is attached to the power receiving portions 33, 33 of the fixing rolls 29, 29a.
2 may be detachably fixed and used as a power supply means for supplying power by the pressure contact power supply brushes 36a, 36a similar to that in FIG. The press-contact power supply brushes 36a, 36a are fixed to a desired frame (not shown), and are connected by a power source 38 and a wiring member 39. And the power supply ring 4
By using 2, 42, the power receiving units 33, 33 of the fixing roll 29, which occur when the power receiving units 33, 33 of the fixing roll 29 and the pressure contact power supply brushes 36a, 36a are in direct contact with each other in a sliding state and power is supplied. It is possible to prevent wear on the surface and abnormal wear due to arc discharge.

Further, the electromagnetic induction action may be used to supply power without using a contact. The feeding means using this electromagnetic induction action will be described with reference to FIGS. 8A and 9. In the fixing device 24a, the sub-frame 43 extending in parallel with the one standing portion 26 formed on the frame 27 is provided. It is provided. Then, as shown in FIG. 9, a power feeding coil core 44 having a substantially cylindrical shape is provided at an appropriate position of the sub-frame 43.
Is stuck. Further, an annular groove 45 having an appropriate size and depth is formed at one end of the feeding coil core 44, and a feeding coil 46 having a desired number of turns is arranged in the groove 45. The power feeding coil 46 is connected to a power source 38 provided at an appropriate position by a desired wiring member 39. Further, as shown in FIGS. 8B and 9, one end of each of the power receiving portions 33, 33 of the fixing roller 29a formed in the shape of a hollow pipe has a shaft center so as to cover the power receiving portions 33, 33. A power receiving coil core 47 having a hole formed therein is fixed.
An annular groove 45a having an appropriate size and depth is formed on the axially outer end surface of the power receiving coil core 47 so as to face the annular groove 45 formed at one end of the power feeding coil core 44. A power receiving coil 48 having a desired number of turns is arranged in 45a. Further, power supply rings 49a and 49b are fixed to the ends of the power receiving units 33 and 33 on the release layer 32 side. Then, one end of the power receiving coil 48 is connected to the one power supply ring 49a which is in close proximity from the outside of the fixing roll 29a by a connecting member 50 having an appropriate shape, and the other end of the power receiving coil 48 is fixed. The other power supply ring 4 passes through the central axis hole inside the roll 29a and a through hole (not shown) bored outward in the radial direction.
9b is connected by a connecting member 50 having an appropriate shape. Further, the power feeding coil 46 and the power receiving coil 48 are arranged in a non-contact state with an appropriate gap S.

With such a structure, electric power can be transmitted from the power feeding coil 46 to the power receiving coil 48 in a non-contact manner by using the electromagnetic induction effect. In this case,
When the number of turns of the power feeding coil 46 is n1, the number of turns of the power receiving coil 48 is n2, and the voltage E1 is applied to the power feeding coil 46,
A voltage E2 is generated in the power receiving coil 48. The relationship between them is E2 = (n2 / n1) × E1. Therefore,
The number of turns n1 of the power feeding coil 46 and the number of turns n2 of the power receiving coil 48
When n and n are the same (n1 = n2), the same voltage as that supplied to the power feeding coil 46 is generated in the power receiving coil 48 and applied to the fixing roll 29a.

FIG. 10 shows the second embodiment of the present invention, and the fixing device 24b of the present embodiment has the structure of the fixing roll 29 of the first embodiment as shown in FIG. 11 (a). And a base 51 made of a substantially cylindrical resin and the base 5
And a heat generating layer 52 formed on the outer surface of
And the release layer 32 formed on the surface of the fixing roller 53, and the fixing roll 53 is formed so as to be integrated with each other. Further, as shown in FIG. 11B, the axial length Ld of the release layer 32 is shorter than the axial length Lc of the fixing roll 53, as in the first embodiment described above. The heat generating layer 52 is exposed at appropriate lengths at both ends in the axial direction of the fixing roll 53 to form power receiving portions 54, 54.

The base 51 is made of a material having heat resistance and insulation, for example, polyimide (PI), polyamideimide (PAI), polyetherimide (PEI), polyetheretherketone (PEEK), polyphenylene sulfite. (PPS), polyether sulfone (PE
S), a material appropriately selected from engineering plastics such as poly-P-xylylene (PPX), is formed by a desired molding method such as injection molding.

The heat generating layer 52 is made of a conductive material having a predetermined resistance value, for example, a carbon-containing conductive ink containing carbon and a resin binder as main components, and the base is formed by an appropriate coating means such as printing. A film having a thickness of about 20 μm is formed thereon. The thickness of the heat generating layer 52 may be appropriately determined according to design specifications, and is not particularly limited to this embodiment.

The other structure is formed in the same manner as in the first embodiment.

According to this embodiment having such a configuration, the same effects as those of the above-described first embodiment can be obtained. For example, the fixing roll 5 used in the fixing device 24b of this embodiment.
When the carbon ink 3 having a resistance value of 4 to 5 Ω is formed on the resin substrate 51 having a diameter of 15 mm to have a thickness of 20 μm and a length of 240 mm, the axial resistance value of the fixing roll 53 is 20 to 25 Ω. Next, 10 is a power source for home use
When a voltage of 0 V is applied, the power consumption can be 500 W or less at a current I = 5 A or less.

Further, the fixing roll 53 can be formed in a hollow pipe shape or the like as in the first embodiment. Further, naturally, various kinds of power feeding means can be applied as in the first embodiment described above.

Further, by using the carbon-containing conductive ink containing carbon and a resin binder as main components, elasticity is imparted to the heat generating layer 52 by the resin binder, and it is possible to improve soft image quality and resolution with little gloss. ..

The present invention is not limited to the above embodiment, but can be modified as necessary.

[0052]

As described above, according to the present invention, a fixing roller having a small diameter which has a simple structure and can maintain high reliability for a long period of time, and a pressing force having a small diameter corresponding to the fixing roller. By using the roll, the fixing device can be downsized and the power consumption can be reduced, which is an extremely excellent effect.

[Brief description of drawings]

FIG. 1 is a perspective view showing a main part of a first embodiment of a fixing device of the present invention.

FIG. 2 is an axial sectional view showing a fixing roll applied to the first embodiment of the fixing device of the present invention.

FIG. 3 is a sectional view of a quadrant in a radial direction showing a fixing roll applied to the first embodiment of the fixing device of the present invention.

FIG. 4 is a sectional view similar to FIG. 2, showing another fixing roll applied to the first embodiment of the fixing device of the present invention.

FIG. 5 is a perspective view in which another power supply unit is applied to the first embodiment of the fixing device of the present invention.

6A is a perspective view similar to FIG. 5 in which yet another power supply means is applied to the first embodiment of the fixing device of the present invention, and b and c.
Is an enlarged sectional view of the power supply means

FIG. 7a is a view similar to FIG. 5 showing still another power supply means,
b and c are enlarged sectional views of the power feeding means, respectively.

FIG. 8 is a view similar to FIG. 5 showing a further power feeding means, and b is a perspective view of a main part.

9 is a sectional view of FIG. 8b.

FIG. 10 is a perspective view showing a main part of a second embodiment of the fixing device of the invention.

11A and 11B are cross-sectional views in a radial direction and an axial direction showing a fixing roll applied to the second embodiment of the fixing device of the present invention.

FIG. 12 is a perspective view showing a main part of a conventional fixing device.

13 is a sectional view of FIG.

FIG. 14 is a perspective view showing a main part of another fixing roll applied to a conventional fixing device.

FIG. 15 is a perspective view showing a main part of still another fixing roll applied to a conventional fixing device.

[Explanation of symbols]

 13 recording medium 19 nip 20 unfixed toner 24, 24a, 24b fixing device 27 frame 29, 29a fixing roll 30 pressure roll 31 mixed molding base 32 release layer 33 power receiving part 36, 36a pressure contact power supply brush 51 base 52 heat generation layer 53 Fixing roll 54 Power receiving unit

Claims (2)

[Claims] 1. A fixing for forming an image by sandwiching and conveying a recording medium having an unfixed toner image mounted between a heating unit and a pressure unit to fix the unfixed toner image on the recording medium. In the apparatus, the heating unit is a heat-generating roll integrally formed by mixing at least a heat-generating element in a resin substrate having heat resistance and insulation. 2. A fixing for forming an image by sandwiching and conveying a recording medium having an unfixed toner image mounted between a heating unit and a pressure unit to fix the unfixed toner image on the recording medium. In the apparatus, the heating means is a heat-generating roll in which a heat-resistant and insulating resin roll is used as a base and a heat-generating layer made of a carbon-containing conductive material is integrally formed on the surface of the base. Characterizing fixing device.