JPH08262901A - Fixing heater, fixing device and image forming device - Google Patents

Abstract

PURPOSE: To make it possible to shorten the warming up time before a roller base body is heated up to a prescribed temp. and to prolong the life of the base body by directly adhering a resistance heating element which is faster in rising of heating than a halogen lamp and has high exothermic efficiency on the inside surface of the roller base body. CONSTITUTION: This fixing heater 10 is constituted to a roller type by forming a heating roller 11 which is the roller base body of a heat resistant and electrically insulating material, for example, alumina ceramics, to a straight cylindrical shape in such a manner that the heater is freely rotatably supported. The heating roller 11 is constituted by forming the film-like resistance heating element 12 mainly composed of, for example, silver, palladium alloy, nickel-tin alloy, etc., directly on nearly the entire inner peripheral surface exclusive of both ends in the axial direction of the roller by thick film printing, etc., to an annular band shape over the entire periphery. The film thickness of the resistance heating element 12 is set to, for example, <=30μm. The resistance heating element 12 which is faster in rising of heating than the halogen lamp and has the high exothermic efficiency is directly deposited on the inside surface of the heating roller 11 in such a manner.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing heater suitable for a roller type to be used by being mounted in small equipment such as office automation equipment, household electric equipment and precision manufacturing equipment, and a copying machine equipped with this fixing heater. The present invention relates to a fixing device used for fixing a toner such as a facsimile and an image forming apparatus using the fixing device.

[0002]

2. Description of the Related Art Generally, in an electronic copying machine, a copy sheet on which a toner image is formed is passed between a fixing heater and a pressure roller while directly or indirectly with a heat-resistant sheet sandwiched between them. The toner on the copy paper is heated and melted and fixed by the heating.

As a conventional fixing heater of this type, for example, a roller type heater constructed as shown in FIG. 10 has been put into practical use. The roller-type fixing heater 1 has a halogen lamp 3 as a heat source and is concentrically built in a base of a cylindrical heating roller 2 made of a metal such as aluminum (Al), stainless steel (SUS), or iron (Fe). On the other hand, a Teflon-based or fluorine-based coating 4 is formed on the outer surface of the heating roller 2, and the heating roller 2 heated by the radiant heat of the halogen lamp 3 is rotatably supported.

The heating roller 2 of the fixing heater 1
And a rotatable pressure roller 5 is lightly and elastically circumscribed to be opposed to each other to form a fixing device. By rotation of both rollers 2 and 5, heat resistance and coating 4 of these rollers 2 and 5 are formed. The copy sheet P on which the toner image T supplied between the film 6 and the film 6 is formed is heated while being pinched, and the toner image T is fixed on the copy sheet P.

[0005]

However, in such a conventional roller type fixing heater 1, the halogen lamp 3 built in the heating roller 2 as a heat source has its electrodes sealed at both ends in the axial direction. Therefore, the amount of heat generated at the axial end of this lamp is low. For this reason, the temperature of both ends of the heating roller 2 in the axial direction corresponding to the both ends of the lamp in the axial direction is lower than that of the intermediate portion, and both ends are exposed to the outside air, so that the heat escape is large and the thermal efficiency is high. Is not good.

Therefore, there is a problem in that the warm-up time required for raising the temperature of the entire heating roller 2 including both axial end portions to a predetermined temperature is, for example, about 40 seconds, and the start-up of heating is prolonged. .

Further, since the heating roller 2 is heated by the radiant heat of the halogen lamp 3, both the heating and pressing rollers 2,
When 5 is rotated at a high speed, both of the rollers 2 and 5 are cooled by the rotating wind and the temperature is lowered, and the toner image T
Is not fixed to the copy paper P. Further, since full power is applied to the halogen lamp 3 at the time of this high speed rotation, power consumption is large and, in addition, disconnection occurs due to electrode wear and the lamp life is not necessarily long.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a fixing heater, a fixing device, and an image forming apparatus which have good heat generation efficiency, a short warm-up time, and a long life. To do.

[0009]

A fixing heater according to a first aspect of the present invention comprises a roller base formed of a heat-resistant electric insulating material in a cylindrical shape; and a resistance heating element directly attached to the inner surface of the roller base. Is provided.

A fixing heater according to a second aspect of the present invention includes a roller base formed of a heat-resistant electric insulating material in a cylindrical shape; a resistor having a film thickness of 30 μm or less, which is directly or indirectly adhered to the inner surface of the roller base. And a heating element.

A fixing heater according to a third aspect of the present invention includes a roller base formed of a heat-resistant electric insulating material in a cylindrical shape; a resistance heating element directly or indirectly attached to an inner surface of the roller base; An electric connection end smaller than the inner diameter of the roller base electrically connected to the heating element is exposed at one end side, and the outer surface other than this electric connection end is constituted by an electric insulator. A terminal internally provided with a resistance heating element and a conductive portion for electrically connecting the electrical connection end portion;

In the fixing heater according to the fourth aspect of the invention, the surface roughness of the outer surface of the roller base is 5 μm or less. Here, the surface roughness means that the height of the minute protrusion protruding on the surface is 5 μm or less.

In the fixing heater according to the fifth aspect of the present invention, a portion of the outer surface of the roller base body that comes into contact with the carrier is covered with a smooth layer.

In the fixing heater according to the sixth aspect of the invention, the portion of the outer surface of the roller base body that comes into contact with the carrier is covered with a smooth layer having elasticity.

A fixing heater according to a seventh aspect of the present invention comprises a conductive layer formed on the outer surface side of the roller base body and charged with the same polarity as that of carbon; and an electrically insulating material for coating the outer surface of the conductive layer with an electrically insulating material. And layers;

The fixing device according to the invention of claim 8 is the fixing device according to claim 1.
7. The fixing heater according to any one of 7 above; disposed so as to press-contact the outer surface or smooth layer of the roller base of the fixing heater, and heat from the resistance heating element forms an image on the fixing target. And a pressure roller that acts on the existing toner and conveys the fixing target.

In the image forming apparatus according to the invention of claim 9, a toner is attached to the electrostatic latent image formed on the medium to form a reverse image, and the reverse image is transferred to a fixing member to form a predetermined image. And a fixing device according to claim 8.

[0018]

In each of the first to seventh aspects of the invention, the heating of the inner surface of the roller base is faster than that of the halogen lamp,
Since the resistance heating element having a high heating efficiency is directly applied, the warming-up time for raising the roller base to a predetermined temperature can be shortened. Moreover, since the resistance heating element does not have an electrode like a halogen lamp, it has a long life.

When the roller base is made of ceramics which is a heat-resistant electric insulating material and the outer surface of the roller base is used as the sliding surface of the body to be fixed, the smoothness of the sliding surface should be improved. In addition, since the ceramic has good thermal conductivity, the heat loss of the resistance heating element can be suppressed as much as possible and efficiently transmitted to the sliding surface.

According to a second aspect of the invention, the film thickness of the resistance heating element is 3
When the thickness is 0 μm or more, when the paste of the resistance heating element is applied by printing on the circular inner peripheral surface of the roller base, sagging occurs and unevenness in the film thickness after firing occurs. For this reason, unevenness in the temperature distribution in the circumferential direction of the roller base body occurs, resulting in uneven fixing of the image. However, in the present invention, the film thickness of the resistance heating element is set to 30 μm or less. It is possible to avoid inconveniences such as drooling that at least affects the image.

According to the third aspect of the present invention, the resistance heating element of the rotating roller base body can be supplied with electric power to be electrically heated via the electric power feeding support portion and the conductive portion of the electric power feeding means.

Since the conductive portion covers the outer surface except the electrical connection end portion projecting outward from the inside of the roller base with an electrically insulating material, the exposure of the conductive portion to the outside is suppressed to a minimum. It is possible to ensure electrical safety such that electrical troubles such as short-circuit with other conductors can be minimized.

According to the fourth aspect of the present invention, since the surface roughness of the outer surface of the roller base body on which the body to be fixed such as copy paper slides is formed to be a smooth surface of 5 μm or less, the fine irregularities on the outer surface cause the surface roughness. Fixing unevenness can be reduced or effectively prevented.

According to the invention of claim 5, since the outer surface of the roller base body on which the carrier slides is coated with the smooth layer, the slidability of the carrier can be improved and the outer surface of the roller base body can be improved. It is possible to effectively prevent the long-life of the roller base body from being shortened due to clogging of many fine holes with the toner adhering to the fixing body.

When the smooth layer is a glass layer having an electric insulation property and a low dielectric constant, the glass layer slides on the resistance heating element on the inner surface side of the roller base and on the outer surface side. Since it is arranged to be interposed between the toner of the carrier and the toner, the toner and the roller base can be electrically insulated by this glass layer. Therefore, it is possible to prevent the toner from being attracted to the roller base body side by the electric attraction force.

According to the sixth aspect of the present invention, since the elastic layer of the fifth aspect uses an elastic material, the toner is fixed by increasing the degree of adhesion with the fixing member sliding on the smooth layer. You can improve your sex.

According to the seventh aspect of the invention, since the conductive layer that is charged to the same electric potential as that of carbon, which is the main component of the toner, is provided on the outer surface side of the roller base, the toner is electrically repelled by the conductive layer. Can be made. This makes it possible to prevent the toner from being electrically attracted to the roller base. Further, since the outer surface of the conductive layer is covered with an electrically insulating layer such as a glass layer, electrical troubles such as short circuit with other conductors of the conductive layer can be prevented and electrical characteristics can be stabilized. can do.

Since the fixing device of the eighth aspect of the invention and the image forming apparatus of the ninth aspect have the fixing heater according to any one of the first to seventh aspects, the function of the fixing heater can be obtained.

[0029]

Embodiments of the present invention will be described below with reference to FIGS. 1 to 9, the same or corresponding parts are designated by the same reference numerals.

FIG. 1 is a half-cut vertical sectional view of an embodiment of a fixing heater according to the present invention. As shown in FIG. 1, the fixing heater 10 includes a heating roller 11 which is a roller base and a heat-resistant and electrically insulating material. It is made of a conductive material such as alumina (Al ₂ O ₃ ) ceramics in the form of a straight cylinder, and is of a roller type so as to be rotatably supported.

The heating roller 11 is formed, for example, to have an outer diameter of 15 mm, an inner diameter of 11 mm, a wall thickness of 2 mm, and an axial length of 360 mm, and as shown in FIG. For example, silver / palladium (Ag / Pd) alloy or (A
g.Pt), nickel-tin (Ni.Sn) alloy, and other film-shaped resistance heating elements 12 are formed in an annular band shape over the entire circumference by thick film printing or the like. Film thickness is set to, for example, 30 μm or less.

Further, as shown in FIG. 3, the heating roller 11 has silver or silver-platinum (Ag.Pt) alloy, silver-palladium alloy (Ag.P) on the inner peripheral surfaces of both axial ends thereof.
A pair of left and right electrodes 13a, 13b in the shape of an annular band made of a good conductor film such as d) are formed over the entire circumference by thick film printing. The inner ends of the electrodes 13a and 13b are electrically connected to both ends of the resistance heating element 12 by overlapping in the vertical direction, for example.

FIG. 4 shows an example of the power feeding means 14,
This is a pair of cylindrical left and right conductive end plugs 1 made of a conductor.
The large diameter inner ends 15a and 16a of the heating roller 1
The inner surfaces of the large diameter inner ends 15a and 16a are firmly fitted and fixed to the inner surfaces of the electrodes 13a and 13b, and are electrically connected.

The outer ends of the respective conductive end plugs 15 and 16 are reduced in diameter so as to slightly project axially outward from both axial ends of the heating roller 11, and the outer peripheral surfaces of the projecting outer ends 15b and 16b. The outer surface of each conductive end plug 15, 16 other than
It is covered with 7a and 17b.

A pair of left and right ring-shaped end rings 1 made of an electrically insulating material are provided on the outer circumferences of the small-diameter end portions of the conductive end plugs 15 and 16.
8 and 19 are tightly fitted to each other, and the small-diameter inner ends 18a and 19a of the end rings 18 and 19 are tightly fitted to both ends of the heating roller 11 so that the conductive cylinders 15 and 16 are fitted to both ends of the heating roller 11. It is firmly fixed in the department.

Each of the conductive end plugs 15 and 16 has a projecting outer end portion 15b or 16b as a power feeding support portion 2 serving as a power feeding support portion.
It is rotatably supported by 0 and 21 and can be fed freely, and a feeding line (not shown) and a temperature control circuit are electrically connected to each feeding bearing 20 and 21. For this purpose, from the power supply line to the power supply bearings 20 and 21, the conductive cylinders 15 and 16,
Power can be supplied to the resistance heating element 12 through the electrodes 13a and 13b in sequence, and the temperature of the resistance heating element 12 can be, for example,
The electric power is controlled to a predetermined electric power of W to 500 W so that the electric power is controlled to be almost constant at a predetermined temperature. The feeding bearings 20 and 21 are electrical insulators 22 and 2
It is fixed to a stationary body such as the chassis 24 via the unit 3.

The outer surface of the heating roller 11 is formed as a smooth surface having a surface roughness of 5 μm or less. Here, the surface roughness of 5 μm or less means that the height of the minute protrusions is 5 μm or less.

However, if the outer surface of the heating roller 11 is exposed to the outside as described above, the toner may be clogged in many fine holes on the outer surface of the ceramic heating roller 11. Once this toner is clogged, it is almost impossible to remove it. In addition, this clogged toner attracts other toner by an electric attraction force, so that the toner is more and more attracted to the outer surface of the heating roller 11. Will shorten the life.

Therefore, as shown in FIG. 5, the heating roller 1
A smooth layer 25 such as a glass layer, a Teflon layer, a fluororesin layer or the like is provided on a portion of the outer surface of No. 1 where a carrier such as a copy sheet comes into contact.
By forming the entire circumference by thick film printing, etc.,
You may comprise so that adhesion of the toner to the outer surface with the heating roller 11 may be prevented.

Further, as shown in FIG. 6, the heating roller 11
A conductive layer 26 charged to the same polarity as carbon, which is the main component of the toner, is formed over the entire circumference by thick film printing or the like, and the conductive layer 26 is covered with an electrically insulating layer such as a glass layer 27. You may.

Therefore, according to this embodiment, the resistance heating element 12 having a higher heating efficiency than the halogen lamp 3 and having a higher heating efficiency is directly attached to the inner surface of the heating roller 11, so that the curve A in FIG. As shown in, the warming-up time for raising the heating roller 11 to a predetermined temperature can be shortened as compared with the conventional example (see FIG. 10) indicated by the curve B in FIG. Moreover, since the resistance heating element 12 does not have an electrode like the halogen lamp 3, it has a long life.

The base of the heating roller 11 is made of ceramics, which is a heat-resistant electric insulating material, and the outer surface of the heating roller 11 is used as the sliding surface of the fixed body such as copy paper. The smoothness can be improved.
Further, since ceramics have good thermal conductivity, it is possible to suppress the loss of heat generated by the resistance heating element 12 as much as possible and efficiently transmit the heat to the sliding surface.

If the resistance heating element 12 is thickened to 30 μm or more by thick film printing or the like, the resistance heating element 12 is thickened.
When this paste is applied by printing onto the circular inner peripheral surface of the heating roller 11, sagging occurs and unevenness occurs in the film thickness after firing.
For this reason, unevenness occurs in the temperature distribution in the circumferential direction of the heating roller 11, which causes uneven fixing. However, in the present embodiment, the film thickness of the resistance heating element 12 is set to 30 μm or less. It is possible to prevent the sagging of the film and the inconvenience such as uneven fixing.

Further, the feeding bearing 2 of the feeding means 14
It is possible to supply electricity to the resistance heating element 12 of the rotating heating roller 11 through the 0, 21, the conductive cylinders 15, 16, and the electrodes 13a, 13b in order to perform electric heating.

The conductive cylinders 15 and 16 are covered with electrical insulating layers 17a and 17b on the outer surfaces other than the projecting outer end portions 15b and 16b which project outward from both ends of the heating roller 11. Since exposure to the outside is suppressed as much as possible, electrical troubles such as short-circuit with other conductors can be effectively prevented, and electrical safety can be ensured.

Further, since the surface roughness of the outer surface of the heating roller 11 on which the object to be fixed such as copy paper slides is formed to be a smooth surface of 5 μm or less, uneven fixing due to minute irregularities on the outer surface is reduced. Or can be effectively prevented.

The heating roller 11 on which the carrier slides
When the outer surface of the heating roller 11 is covered with the smooth layer 35, the slidability of the carrier can be improved, and at the same time, many fine holes on the outer surface of the heating roller 11 are filled with the toner adhering to the fixing target. It is possible to effectively prevent clogging and shortening of the life of the roller base body. As a result, it is possible to prevent the copy sheet from being soiled with the toner.

When the smooth layer 25 is a glass layer having an electric insulating property and a low dielectric constant, the glass layer covers the resistance heating element 12 on the inner surface side of the heating roller 11 and the outer surface side. Since it is arranged to intervene between the sliding carrier and the toner, the toner and the roller base can be electrically insulated by this glass layer. Therefore, it is possible to prevent the toner from being attracted to the heating roller 11 side by the electric attraction force.

Moreover, when an elastic material is used as the smooth layer, the toner fixability can be improved by increasing the degree of adhesion with the fixed body sliding on the smooth layer.

Further, since the conductive layer 26 that is charged to the same electric potential as the main component of the toner, carbon, is provided on the outer surface side of the heating roller 11, the toner is electrically repelled by the conductive layer 26. You can This can prevent the toner from adsorbing to the heating roller 11. Further, since the outer surface of the conductive layer 26 is covered with an electrically insulating layer such as the glass layer 27, electrical troubles such as short circuit with other conductors of the conductive layer 26 can be prevented and the electrical characteristics can be prevented. Can be stable.

FIG. 8 shows the construction of an embodiment of an electronic copying machine 31 which is a kind of the image forming apparatus of the present invention. The copying machine 31 has a casing 32 and a copy sheet P in a cassette 33. And an image forming unit 34 that forms a toner image corresponding to an image of an original document (not shown) and a fixing device 35 that fixes the toner image on the copy sheet P.

The fixing device 35 is constructed, for example, as shown in FIG. 9, and faces the pressure roller 36 to face the fixing heater 1.
The fixing heater 10 is rotatably supported by the housing 32, and the silicone rubber layer 3 of the pressure roller 36 is arranged.
It is in elastic contact with 7.

The fixing heater 10 includes a pair of electrodes 13
The resistance heating element 12 is energized through the conductive cylinders 115 and 16 in contact with a and 13b and the power feeding bearings 20 and 21.
Heats up and is heated by the heating roller 11. Therefore,
The unfixed toner image T is melted by pinching the copy paper P on which the toner image T is formed and heating it by the fixing heater 10 between the outer surface of the heating roller 11 and the silicone rubber layer 37 of the pressure roller 36. However, it can be fixed on the copy paper P.

Further, since the fixing heater 10 has a good heat generation efficiency, a short warming-up time and a long life as described above, the fixing heater 35 and the electronic copying machine 31 have a short warming-up time. It has a long life.

[0055]

As described above, in each of the first to seventh aspects of the invention, the resistance heating element, which has a higher heating efficiency than the halogen lamp and has a higher heating efficiency, is directly attached to the inner surface of the roller base. Therefore, it is possible to shorten the warm-up time for raising the roller base body to a predetermined temperature. Moreover, since the resistance heating element does not have an electrode like a halogen lamp, it has a long life.

When the roller base is made of ceramics, which is a heat-resistant electric insulating material, and the outer surface of the roller base is used as the sliding surface of the body to be fixed, the smoothness of the sliding surface should be improved. In addition, since the ceramic has good thermal conductivity, the heat loss of the resistance heating element can be suppressed as much as possible and efficiently transmitted to the sliding surface.

According to a second aspect of the invention, the film thickness of the resistance heating element is set to 3
When the thickness is 0 μm or more, when the paste of the resistance heating element is applied by printing on the circular inner peripheral surface of the roller base, sagging occurs and unevenness in the film thickness after firing occurs. For this reason, unevenness in the temperature distribution in the circumferential direction of the roller base body occurs, resulting in uneven fixing of the image. However, in the present invention, the film thickness of the resistance heating element is set to 30 μm or less. It is possible to avoid inconveniences such as drooling that at least affects the image.

According to the third aspect of the present invention, the resistance heating element of the rotating roller base body can be supplied with electric power to be electrically heated via the electric power feeding support portion and the conductive portion of the electric power feeding means.

Since the conductive portion covers the outer surface other than the electrical connection end portion projecting outward from the inside of the roller base with an electrically insulating material, the exposure of the conductive portion to the outside is suppressed to a minimum. It is possible to ensure electrical safety such that electrical troubles such as short-circuits with other conductors can be minimized.

According to the fourth aspect of the present invention, since the surface roughness of the outer surface of the roller base body on which the object to be fixed such as copying paper slides is formed to be a smooth surface of 5 μm or less, the unevenness of the outer surface is caused. Fixing unevenness can be reduced or effectively prevented.

According to the fifth aspect of the present invention, since the outer surface of the roller base on which the carrier slides is coated with the smooth layer, the slidability of the carrier can be improved and the outer surface of the roller base can be improved. It is possible to effectively prevent the long-life of the roller base body from being shortened due to clogging of many fine holes with the toner adhering to the fixing body.

When the smooth layer is a glass layer having an electric insulation property and a low dielectric constant, the glass layer slides on the resistance heating element on the inner surface side of the roller base and on the outer surface side. Since it is arranged to be interposed between the toner of the carrier and the toner, the toner and the roller base can be electrically insulated by this glass layer. Therefore, it is possible to prevent the toner from being attracted to the roller base body side by the electric attraction force.

According to the sixth aspect of the present invention, since an elastic layer is used as the smoothing layer of the fifth aspect of the invention, the fixing property is improved by increasing the degree of adhesion with the fixed body sliding on the smoothing layer. Can be increased.

According to the seventh aspect of the invention, since the conductive layer charged to the same electric potential as that of carbon, which is the main component of the toner, is provided on the outer surface side of the roller substrate, the toner is electrically repelled by the conductive layer. Can be made. This makes it possible to prevent the toner from being attracted to the roller base. Further, since the outer surface of the conductive layer is covered with an electrically insulating layer such as a glass layer, it is possible to prevent electrical troubles such as a short circuit with other conductors of the conductive layer in advance.
The electric characteristics can be stabilized.

Since the fixing device of the eighth aspect of the invention and the image forming apparatus of the ninth aspect have the fixing heater according to any one of the first to seventh aspects, the effect of this fixing heater is exhibited.

[Brief description of drawings]

FIG. 1 is a longitudinal cross-sectional view of a main part of an embodiment of a fixing heater according to the present invention.

FIG. 2 is an end view of a section cut along line II-II in FIG.

FIG. 3 is an enlarged view of part III in FIG. 1.

FIG. 4 is a partially enlarged vertical cross-sectional view of an example of a power supply unit of the embodiment shown in FIG.

FIG. 5 is a longitudinal sectional view of a main part of another embodiment of the present invention.

FIG. 6 is a longitudinal sectional view of a main part of still another embodiment of the present invention.

FIG. 7 is a graph showing the rise of heating in the example shown in FIG. 1 and the like together with the conventional example.

FIG. 8 is an overall configuration diagram of an embodiment of an image forming apparatus according to the present invention.

FIG. 9 is an overall configuration diagram of an embodiment of a fixing device according to the present invention.

FIG. 10 is a configuration diagram of a conventional roller type fixing heater.

[Explanation of symbols]

 Reference Signs List 10 fixing heater 11 heating roller 12 resistance heating element 13a, 13b electrode 14 power supply means 15, 16 pair of conductive end plugs 15a, 16a protruding outer end portions of a pair of conductive end plugs 17a, 17b electric insulating layer 18, 19 pair End ring 20,21 Feeding bearing 24 Chassis 25 Smoothing layer 26 Conductive layer 27 Glass layer 31 Electronic copying machine (image forming apparatus) 32 Housing 33 Cassette 34 Image forming unit 35 Fixing device 36 Pressure roller 37 Silicon rubber layer P Copy paper T Toner image

Claims (9)

[Claims] 1. A fixing heater comprising: a roller base formed of a heat-resistant electrically insulating material in a cylindrical shape; and a resistance heating element directly attached to an inner surface of the roller base. 2. A roller base formed of a heat-resistant electric insulating material in a cylindrical shape; a resistance heating element having a film thickness of 30 μm or less, which is directly or indirectly adhered to the inner surface of the roller base;
A fixing heater comprising: 3. A roller base formed of a heat-resistant electrically insulating material in a cylindrical shape; a resistance heating element directly or indirectly attached to the inner surface of the roller base; electrically connected to the resistance heating element. The electric connection end, which is smaller than the inner diameter of the roller base, is exposed at one end side, and the outer surface other than this electric connection end is made of an electric insulator, and a resistance heating element is provided inside the electric insulator. And a terminal having a conductive portion for electrically connecting the electric connection end portion, and a fixing heater. 4. The surface roughness of the outer surface of the roller substrate is 5 μm.
The following is any one of Claims 1-3 characterized by the following.
The fixing heater according to the item. 5. The fixing heater according to claim 1, wherein the roller base is formed by covering a portion of the outer surface of the roller base that comes into contact with the carrier with a smooth layer. 6. The fixing heater according to claim 1, wherein the roller base is formed by coating a portion of the outer surface thereof that comes into contact with the carrier with a smooth layer having elasticity. . 7. A conductive layer formed on the outer surface side of the roller base body and charged with the same polarity as carbon; and an electrically insulating layer coating the outer surface of this conductive layer with an electrically insulating material. The fixing heater according to any one of claims 1 to 6, wherein: 8. The fixing heater according to any one of claims 1 to 7, which is arranged so as to press-contact an outer surface or a smooth layer of a roller base of the fixing heater, and heat generated from a resistance heating element. A fixing device comprising: a pressure roller that acts on the toner forming the image of the fixing target and conveys the fixing target. 9. A means for adhering toner to an electrostatic latent image formed on a medium to form a reversal image, and transferring the reversal image to a fixing member to form a predetermined image; An image forming apparatus comprising: a fixing device;