JPH0749630A - Thermal fixing device and temperature control method - Google Patents

Abstract

PURPOSE:To provide a thermal fixing device and a temperature control method shortening a waiting time for attaining a fixing temperature after a power is supplied and capable of temperature control having excellent followup ability for a set temperature. CONSTITUTION:A press-contact roller 4 comes in press-contact with a heating roller 27 constituted so that a releasable coating layer is provided on the outer surface of a thin pipe-like fiber reinforced composite material assemblage disposed of fiber reinforced composite material on an uniform density and impregnated with heat-resistant resin as a binder, and a halogen lamp 5 is internally provided; and the halogen lamp 5 is continuously turned on up to a first set temperature at which fixing can be performed, and the heating roller 27 is heated by switching to flickering lighting where the upper limit of lighting time is set as <=50% of a rush current flow time up to a second set temperature that is a little higher control reference value than the first set temperature after attaining the first set temperature, and is respectively rotated in the directions of arrows A and B so as to come in press-contact with the paper 2, so that the toner 2a is stuck by fusion to the paper 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat fixing device used in electrophotographic printers, copying machines, facsimiles and the like.

[0002]

2. Description of the Related Art Conventionally, in an electrophotographic printer, a copying machine, a facsimile, etc., a pressure roller which is rotatable relative to a heating roller having a heating element therein with a conveying path for a sheet on which a toner is transferred being sandwiched. A heating and fixing device is used in which a sheet of paper is pressed against a sheet of paper while the sheet of paper is pressed against the sheet of paper while rotating a heating roller heated to a preset temperature at which fixing can be performed by a heating element.

FIG. 9 is a schematic block diagram showing a conventional example. The heating and fixing device 1 is provided with a heating roller 3 and a pressure contact roller 4 with a sheet conveying path for the sheet 2 interposed therebetween. Heating roller 3
Has a halogen lamp 5 as a heating element inside an aluminum roller base material. The pressure contact roller 4 has silicone rubber or the like as a releasable elastic layer 7 on the surface of the roller base material 6, and is supported by a bearing urged toward the heating roller 3 by a coil spring (not shown). There is. The bearing is slidably supported on a side frame of a main body device (not shown). Temperature detecting means 8 such as a thermistor for detecting the surface temperature is provided on the surface of the heating roller 3. The energization control unit 9 energizes the halogen lamp 5 via the temperature detecting means 8 so that the surface temperature of the heating roller 3 follows the set temperature at which fixing is possible.

FIG. 10 shows a conventional time chart.

At time t0, the power is turned on. The energization controller 9 energizes the halogen lamp 5 to continuously light the halogen lamp 5 to heat it. The energization controller 9 detects the surface temperature of the heating roller 3 via the temperature detector 8.

At time t1, the energization control unit 9 detects that the surface temperature of the heating roller 3 has reached a set temperature T at which fixing is possible, and thereafter controls the temperature based on the set temperature T. That is, the set temperature T is used as the reference while following the overshoot.
When the fixing operation is started in this state, the heating roller 3 and the pressure contact 4 roller are rotated in the directions of arrows A and B, respectively, by the driving means (not shown). Then, the sheet 2 conveyed in the direction of the arrow C along the sheet conveying path is heated and pressure-contacted to the toner-2a.
Is fused to paper 2.

[0007]

In the conventional heat fixing device, since the roller made of aluminum having a thickness of 2 to 3 mm is used as the roller base material of the heating roller, the heat capacity is large. Therefore, there is a problem that a long waiting time is required until the set temperature is reached after the power is turned on.

Further, in addition to having a large heat capacity, the thick wall of the roller base material causes a delay in heat conduction, and the overshoot temperature range with respect to the set temperature is widened to be fine. There was also the problem of obstructing temperature control.

It is an object of the present invention to provide a heating and fixing device and a temperature control method which shorten the waiting time from turning on the power to reach the set temperature and have excellent followability to the set temperature. .

[0010]

In order to achieve the above object, in the heat fixing device of the present invention, the heating roller has the fiber reinforced composite material arranged at a uniform density and impregnated with a heat resistant resin as a binder. The thin-walled pipe-shaped fiber-reinforced composite material aggregate is provided, and a coat layer having releasability is applied to the outer surface.

[0011]

The heating roller of the heating and fixing device configured as described above is composed of a thin pipe-shaped fiber-reinforced composite material aggregate and has a small heat capacity and a thin wall thickness, so that it is easy to warm up and Is easily conducted to the surface of the roller.

Therefore, it is possible to provide a heating and fixing device and a temperature control method which can shorten the waiting time from when the power is turned on until the fixing temperature is reached and which is excellent in followability to the set temperature.

[0013]

Embodiments of the present invention will be described with reference to the drawings. Elements common to the drawings are given the same reference numerals.

First Embodiment FIG. 2 is a schematic configuration diagram of an electrophotographic printer showing a first embodiment. The electrophotographic printer has a paper feed unit 12 at one end of the paper transport path 11 and a paper discharge unit 13 at the other end. A registration roller 14, an image forming unit 15, and a heat fixing device 16 are arranged on the sheet conveying path 11 from the side of the sheet feeding unit 12. In the paper feed unit 12, the feeding roller 17 separates the paper 2 from the paper cassette 18 one by one and feeds it. The registrar roller 14 is used to feed the paper 2 once fed out.
After the front end of the sheet is stopped and the skew is corrected, the sheet 2 is rotated to convey the sheet 2 to the image forming section 15.

The image forming section 15 is provided with a photoconductor drum 20 and a toner transfer device 21 with the sheet conveying path 11 interposed therebetween.
The photosensitive drum 20 is rotatably supported by a side frame (not shown), and is rotated at a predetermined rotation speed by a driving means (not shown). A charger 22 and a light source 2 are provided around the photosensitive drum 20.
3, a developing device 24, a separation charging device 25, a cleaner 26 and the like are provided.

The surface of the photosensitive drum 20 is a separation charger 2
5. After being made uncharged by the cleaner 26, it is uniformly negatively charged by the charger 22. The surface of the photosensitive drum 20, which is uniformly negatively charged, is exposed by the light source 23 based on the print data, and the exposed portion is made conductive to form an electrostatic latent image in a state of approximately 0V. Developer 2
In No. 4, a toner charged negatively is attached to the electrostatic latent image for development.

The toner transfer device 21 applies a positive charge from the back side of the paper 2 on the paper transport path 11 by corona discharge, and transfers the toner from the photosensitive drum 20 to the front side of the paper 2 by electrostatic attraction. The heat fixing device 16 heats and presses the sheet 2 to which the toner is attached to fuse the toner to the sheet 2.

FIG. 1 is a schematic configuration diagram of a heat fixing device of the first embodiment, and FIG. 3 is an enlarged partial sectional view of a heating roller. The difference from the prior art is the structure and temperature control of the heating roller. The heating roller 27 is a thin-walled pipe-shaped fiber-reinforced composite material assembly in which the fiber-reinforced composite material is arranged at a uniform density and is impregnated with a heat-resistant resin as a binder, and a coating layer having releasability is provided on the outer surface. It was applied to. For example, in FIG.
As shown in (A), a large number of single fiber carbon fibers 28 having the same length as the heating roller 27 are arranged at a uniform density.
A thin-walled pipe-shaped carbon fiber assembly having an outer diameter of 20 mm and a wall thickness of 0.1 to 0.8 mm impregnated with a heat-resistant resin as a binder 29 in an amount of 5 to 50 wt% (weight%). On the surface, a coat layer 30 of fluorine resin or the like is provided which has excellent releasability and prevents toner offset.

A commercially available single fiber carbon fiber 28 having a diameter of 5 to 10 μm is suitable. The single fiber carbon fiber 28 may be arranged not only in the roller axial direction but also in a direction perpendicular to the axial direction as shown in FIG. 3 (B), or as shown in FIG. 3 (C). The fibers may be woven in the axial direction and in a direction perpendicular to the axial direction as shown. When weaving, glass fiber may be used instead of carbon fiber.

Polyimide, polyphenylene sulfide and the like are also suitable for the binder 29, but the binder 29 is not limited to these.

The heating roller 27 thus constructed has a specific strength (strength / specific gravity) of about 3 times that of steel, and a specific elasticity of about 3 to 3 times that of steel.
4 times as much, and high flexural rigidity is obtained compared to aluminum products, and the thickness is 1/10 to 1/1 compared to aluminum products.
It can be set to 3.

Further, since the thermal conductivity of the carbon fiber is at the same level as that of mild steel, it is easy to make the temperature gradient in the axial direction uniform.
This reduces the heat capacity of the heating roller.

Therefore, since it is easy to warm up, it is possible to shorten the waiting time from turning on the power to reaching the fixing temperature.

Further, since the heat capacity is reduced and the wall thickness is thinned, heat is easily transferred to the roller surface, so that temperature control with excellent followability with respect to the set temperature is possible. Become.

Next, the operation of the first embodiment will be described with reference to FIG. FIG. 4 is a time chart of the heat fixing device of the first embodiment.

The power is turned on at time t0. The energization controller 9 energizes the halogen lamp 5 to continuously light the halogen lamp 5 to heat it. The energization control unit 9 detects the surface temperature of the heating roller 27 via the temperature detecting means 8. Heating roll
The la 27 is likely to be warmed due to the reduced heat capacity, and the surface temperature rises rapidly.

At time t1, the energization control unit 9 turns on the heating roller 27.
It is detected that the surface temperature of has reached the first settable temperature TL at which fixing is possible, and the halogen lamp 5 is switched from continuous lighting to blinking lighting. The first settable temperature TL at which fixing is possible means, for example, the lower limit temperature of the fixing temperature range.

At time t2, the energization control unit 9 turns on the heating roller 27.
It is detected that the surface temperature has reached the second set temperature TS, which is a control reference value slightly higher than the first set temperature TL, and thereafter the temperature is controlled based on the second set temperature TS. That is, follow-up control is performed with respect to the second set temperature TS. Heating roller 2
Since the heat capacity of No. 7 is small and the wall thickness is thin, the thermal conductivity is improved and the temperature control excellent in followability by narrowing the overshoot temperature range can be performed. Then, as shown in FIG. 1, the sheet 2 to which the toner-2a is attached is conveyed from the image forming section 15 to the heat fixing device 16 during this period.
The energization controller 9 rotates the heating roller 27 together with the pressure roller to heat and press the sheet 2 to fuse the toner-2a to the sheet 2.

When the fixing operation is completed at time t3, the energization control unit 9 does not need to heat the heating roller 27, so that the energization of the halogen lamp 5 is stopped.

At time t4, the energization controller 9 starts the fixing operation again. At this time, the energization controller 9 continuously lights the halogen lamp 5 if the surface temperature of the heating roller 27 is lower than the first set temperature TL, and flashes it if it is higher than the first set temperature TL.

At time t5, the energization control unit 9 switches the halogen lamp 5 from continuous lighting to blinking lighting. After that, the same operation is repeated.

In the case of performing the fine control as in this embodiment, the halogen lamp has a lamp wall temperature of about 250 in a lighting state.
If you do not cycle the halogen cycle above ℃,
Care must be taken as the lamp life will be shortened.

Further, the upper limit of the lighting time for one halogen lamp is 5 which is the time for generating the inrush current to the lamp in consideration of the life of the lamp.
It is preferable to suppress it to about 0%.

Although a halogen lamp of the type used in the prior art may be used as the halogen lamp, the halogen lamp 32 as shown in FIG. 5 is used by taking advantage of the low heat capacity of the heating roller according to the present invention. When used, the heating effect can be further enhanced.

FIG. 5 is a sectional view of the improved halogen lamp. That is, the reflecting mirror surface 34 is provided on the surface of the lamp tube wall 33, and the radiation rays from the filament 35 are collected in the sheet carrying-in direction including the pressure contact portion. That is, the surface of the heating roller may be supplied with radiant rays so as to reach the set temperature before reaching the pressure contact portion. By heating an unnecessary area of the heating roller by this, the internal temperature rise of the heat fixing device can be reduced, and by extension, the internal temperature rise of the printer can be reduced.
The reflecting mirror surface 34 is formed by plating or vapor-depositing gold or aluminum on the outer wall 33 of the lamp tube.

The halogen lamp and the heating roller are not concentric with each other, and may be eccentric in order to efficiently heat the heating range.

Second Embodiment FIG. 6 is a schematic diagram of the heat fixing device of the second embodiment.
FIG. 7 is a sectional view taken along the line AA of FIG. FIG. 6 is a sectional view showing a portion necessary for explanation.

The major difference between this embodiment and the first embodiment is that the heating element is a carbon fiber and the jule heat generated when an electric current is passed through the carbon fiber is used. Therefore, the structure of the heating roller is
When it is composed of a bon fiber, the heating roller of the first embodiment is used.
However, when it is constructed with glass fibers, a thin layer in which glass fibers having a diameter of about 5 to 10 μm are arranged in parallel in the axial direction is provided inside and a thin layer of carbon fibers is provided outside. .

Next, a specific structure for supplying power to the heating roller will be described. The ends of the heating roller 40 are fitted with bearing rings 41 and 42 on the outer circumference, respectively, and the conductive ring 4 is fitted on the inner circumference.
3, 44 are fitted and the periphery is joined with a rivet 45. The bearing rings 41 and 42 are supported by bearings 46 and 47 fixed to a frame (not shown). Bearing ring 41
The outer circumference of the heating roller engages with a drive gear (not shown).
A driven gear 41a for rotating the rotor 40 is provided.

The feeding means 4 is provided on the conductive rings 43 and 44.
8 and 49 are provided respectively. The power supply means 48 comprises a conductive spring spring 50, a magnetic electrode plate 52, a fixed electrode 54, and an electromagnetic magnet 56. Similarly, the power feeding means 49 comprises a conductive spring 51, a magnetic electrode plate 53, a fixed electrode 55, and an electromagnetic magnet 57.
One end of each of the springs 50 and 51 has a conductive ring 43,
It is fixed to 44 with one rivet 45. The magnetic electrode plates 52 and 53 are disposed so as to face the mainsprings 50 and 51, respectively, and the plate surfaces 52a and 53a are substantially aligned with the axis of the heating roller 40 so that the heating roller 40 is heated. Shafts 52b and 53b extending to the 40 side are integrally provided. The other ends of the springs 50 and 51 are fixed to the shafts 52b and 53b, respectively.

Electromagnetic magnets 56 and 57 are fixed to the side frames 58 and 59, and the cores 56a and 57a of the electromagnetic magnets 56 and 57 are fixed electrodes 5.
The magnetic electrode plates 52 and 53 are provided so as to face each other through the magnetic field plates 4 and 55. Coil 56 of electromagnetic magnets 56 and 57
b and 57b and the fixed electrodes 54 and 55 are connected to the energization control unit 60 shown in FIG.

The pressure contact roller 4 has a shaft 4a supported by a frame (not shown) via bearings 61 and 62. Bearing 61,
Reference numeral 62 denotes an urging member (not shown) which is urged toward the heating roller 40, and the roller surface is in pressure contact with the heating roller 40. A sensor 63 for detecting the rear end of the sheet 2 is provided on the sheet conveyance path 11 and is connected to the energization control unit 60.

Next, the operation of the second embodiment will be described.
Since the control method is the same as that of the first embodiment, refer to FIG.

At time t0, the power is turned on. Energization control unit 60
Energizes the coils 56b and 57b of the electromagnetic magnets 56 and 57 and the fixed electrodes 54 and 55. Electromagnetic magnet 5
6 and 57 are excited to attract the magnetic electrode plates 52 and 53 to the fixed electrodes 54 and 55. The heating roller 40 is energized through mainspring springs 50 and 51 and conductive rings 43 and 44 to generate jule heat. The energization control unit 60 detects the surface temperature of the heating roller 40 via the temperature detecting means 8. Since the heating roller 40 has a small heat capacity, the heating roller 40 is easily warmed, and the surface temperature rises rapidly.

At time t1, the energization controller 60 controls the heating roller 4
It is detected that the surface temperature of 0 has reached the first settable temperature TL at which fixing is possible, and the heating roller 40 is switched from continuous energization to intermittent energization. The first settable temperature TL at which fixing is possible means, for example, the lower limit temperature of the fixing temperature range.

At time t2, the energization controller 60 controls the heating roller 4
Detecting that the surface temperature of 0 has reached the second set temperature TS, which is a control reference value slightly higher than the first set temperature TL,
After that, the temperature is controlled based on the second set temperature TS. That is,
Follow-up control is performed with respect to the second set temperature TS. Since the heat capacity of the heating roller 40 is reduced and the wall thickness is reduced, the thermal conductivity is improved and the temperature control with excellent followability by narrowing the overshoot temperature range can be performed. Then, as shown in FIG. 7, the sheet 2 having the toner-2a attached thereto is conveyed from the image forming section 15 to the heating and fixing device 16 during this period, so that the energization control section 60 presses the heating roller 40 into pressure contact with the roller. 4, the paper 2 is heated and pressed to fuse the toner-2a to the paper 2. While the sheet 2 is passing through the heat fixing device 16, the energization controller 60 detects the rear end of the sheet 2 via the sensor 63.

When the energization controller 60 detects the trailing edge of the sheet 2 at time t3, energization of the heating roller 40 is stopped. Then, the electromagnetic magnets 56 and 57 are demagnetized.

At time t4, the energization controller 60 restarts the fixing operation. At this time, the energization control unit 60 causes the heating roller 4 to
If the surface temperature of 0 is lower than the first set temperature TL, continuous energization is performed, and if the surface temperature is higher than the first set temperature TL, intermittent energization is performed.

At time t5, the energization control unit 60 switches from continuous energization to intermittent energization. After that, the same operation is repeated.

The control has been described above. Here, the state where the fixing operation is started and the heating roller 40 is rotated will be described. The springs 50 and 51 are connected to the shafts 52b of the magnetic electrode plates 52 and 53 as the heating roller 40 rotates.
It is wound around 53b and stores resilience. And paper 2
When the rear end is detected and the fixing operation is completed, the electromagnetic magnets 56 and 57 are demagnetized, and the magnetic electrode plates 52 and 53 are fixed to the fixed electrodes 54 and 55 by the torsional force of the springs 50 and 51.
Keep away from. The magnetic electrode plates 52 and 53 are fixed electrodes 5.
When separated from 4, 55, the restoring force stored in the springs 50, 51 is released in a short time.

Before starting the fixing operation for the next sheet, the electromagnetic magnets 56 and 57 are excited to heat the roller.
The heating roller 40 is energized and the surface temperature of the heating roller 40 is controlled at a second set temperature TS.

The mainsprings 50 and 51 are heating rollers 4
It is necessary to store the rotation amount of the heating roller 40 until 0 starts rotation and at least the rear end of the longest sheet used in this printer is detected by the sensor 63. The attraction force of the electromagnetic magnets 56 and 57 is the spring 50,
It has the strength to fix the magnetic electrode plates 52 and 53 to the fixed electrodes 54 and 55 against the restoring force of 51.

In the present embodiment, the mainsprings 50 and 51 store the rotation amount of the heating roller 40 for one sheet, but it may be stored for a plurality of sheets in consideration of the attractive force of the electromagnetic magnets 56 and 57. .

Further, the power feeding means is provided with a rotary shaft integrally with the conductive ring at the center of the conductive ring, and the rotary shaft is slidably supported by the fixed side contactor to feed power to the heating roller. Good.

According to the second embodiment, the heating roller is not directly heated by an indirect heating element such as a halogen lamp but is directly heated, so that the surface of the heating roller is heated to a set temperature with a small amount of power consumption. be able to.

As a pressure contact roller for pressure contact with the heating rollers of the first and second embodiments, as shown in FIG. 8, a pressure contact roller 71 is a heat resistant thin film belt made of silicone rubber, polyimide or the like. 72 and a pair of rotatable rollers 73 and 74 may be provided to increase the nip width at which the sheet 2 and the heating roller surface come into contact with each other. In this case, since the pressure applied to the heating roller can be reduced, the thickness of the heating roller can be further reduced, and the heat capacity can be further reduced.

[0057]

Since the present invention is constructed as described above, it has the following effects.

The heating roller is a thin-walled pipe-shaped fiber-reinforced composite material aggregate in which the fiber-reinforced composite material is arranged at a uniform density and is impregnated with a heat-resistant resin as a binder, and a coating layer having releasability. The heat capacity is small and the wall thickness is thin because it is applied to the outer surface, so it is easy to warm up and heat is easily transferred to the roller surface, so the waiting time from turning on the power to reaching the fixing temperature is shortened. You can

Further, since the heat capacity is reduced, the electric energy for heating the heating roller can be reduced and the energy can be saved.

Further, since the heat capacity is reduced, the temperature is easily warmed up and the temperature is easily cooled down. Therefore, the delay of the temperature control is reduced, and the temperature control excellent in followability with respect to the set temperature at which fixing can be performed becomes possible.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a heat fixing device according to a first embodiment.

FIG. 2 is a schematic configuration diagram of an electrophotographic printer showing a first embodiment.

FIG. 3 is an enlarged partial sectional view of a heating roller.

FIG. 4 is a time chart of the heat fixing device.

FIG. 5 is a sectional view of an improved halogen lamp.

FIG. 6 is a schematic configuration diagram of a heat fixing device according to a second embodiment.

7 is a cross-sectional view taken along the line AA of FIG.

FIG. 8 is a schematic configuration diagram showing a modified example of the present invention.

FIG. 9 is a schematic configuration diagram showing a conventional example.

FIG. 10 is a time chart of a conventional example.

[Explanation of symbols]

 1, 16 Heat fixing device 3, 27, 40 Heating roller 4, 71 Pressure contact roller 5, 32 Halogen lamp 48, 49 Power supply means

Claims (10)

[Claims] 1. A pressure roller which is rotatable with respect to a heating roller having a heating element therein, with a sheet conveying path on which a toner is transferred being sandwiched therebetween.
In a heating and fixing device in which a sheet of paper is pressed against a sheet of paper while rotating a heating roller heated to a set temperature capable of fixing by a heating element to fuse the toner to the sheet of paper, the heating roller is fiber reinforced. A heating characterized in that a composite material is arranged at a uniform density and a coat layer having releasability is applied to the outer surface of a thin-walled pipe-shaped fiber-reinforced composite material assembly impregnated with a heat-resistant resin as a binder. Fixing device. 2. The thin-walled pipe-shaped fiber-reinforced composite material assembly is provided with carbon fibers having at least the same length as the heating roller length at a uniform density in the axial direction, and the heat-resistant resin as a binder. The heat fixing device according to claim 1, wherein the heat fixing device is impregnated with 5 to 50 wt%. 3. A heat-resistant thin film belt and a pair of rotatable rollers wound around the heat-resistant thin film belt.
The heat-fixing device according to claim 1, wherein 4. The heating element is a fiber-reinforced composite material, and a conductive ring provided in contact with the periphery of the end portion of the thin-walled pipe-shaped fiber-reinforced composite material, and power supply for supplying a current to the conductive ring. Means for producing electric current through the fiber-reinforced composite material, and using the heat generated from the fiber-reinforced composite material.
Alternatively, the heat fixing device according to claim 3. 5. The power supply means comprises a conductive spring having one end fixed to the conductive ring, a magnetic electrode plate fixed to the other end of the spring, and a magnetic electrode plate provided with a gap. 5. The heating and fixing device according to claim 4, comprising a fixed electrode opposed to the magnet and an electromagnet for attracting the magnetic electrode plate to bring the magnetic electrode plate into contact with the fixed electrode. 6. The heating element is a halogen lamp, and a reflecting mirror surface is provided on the surface of the lamp tube wall for collecting radiation rays from the filament in a paper loading direction including a pressure contact portion. Alternatively, the heat fixing device according to claim 3. 7. A pressure roller which is rotatable with respect to a heating roller having a heating element therein, with a conveyance path of the sheet on which the toner is transferred being sandwiched therebetween.
In a temperature control method in which a heating roller heated to a set temperature capable of being fixed by a heating element is pressed against a sheet to fuse the toner to the sheet, the heating roller is fiber reinforced. The composite material is arranged at a uniform density, and a thin-walled pipe-shaped fiber-reinforced composite material aggregate impregnated with a heat-resistant resin as a binder is provided with a coating layer having releasability on the outer surface, and the heating element is a halogen lamp. As a result, the halogen lamp is continuously turned on up to the first set temperature, and after reaching the first set temperature, the lighting time is set to the second set temperature which is a control reference value slightly higher than the first set temperature. A temperature control method comprising heating by switching to blinking lighting in which an upper limit is set to 50% or less of inrush current time of a halogen lamp. 8. The temperature control method according to claim 7, wherein the heating roller is impregnated with a heat resistant resin as a binder in an amount of 5 to 50 wt%. 9. A pressure roller which is rotatable with respect to a heating roller having a heating element therein, with a conveyance path for the sheet on which the toner is transferred being sandwiched therebetween.
In a temperature control method in which a sheet of paper is pressed against the sheet of paper while the roller of heating is heated to a set temperature at which it can be fixed by a heating element and the toner is fused to the sheet of paper, the heating roller is at least heated. The carbon fiber having the same length as the roller length is arranged in the axial direction at a uniform density, and the outer surface of the thin-walled pipe-shaped carbon fiber assembly impregnated with 5 to 50 wt% of heat-resistant resin as a binder. A coating layer having releasability is applied, the heating element is a carbon fiber, and a conductive ring provided in contact with the periphery of the end portion of the thin-walled pipe-shaped carbon fiber assembly, and its conductivity. A second setting which is a control reference value that is slightly higher than the first set temperature after the first set temperature is reached and the first set temperature is reached. Heat up to temperature by switching to intermittent power supply Temperature control method characterized Rukoto. 10. The feeding means comprises a conductive spring having one end fixed to the conductive ring, a magnetic electrode plate fixed to the other end of the spring, and a magnetic electrode plate provided with a gap. 10. The temperature control method according to claim 9, comprising a fixed electrode facing the magnetic field plate and an electromagnet for attracting the magnetic electrode plate to bring the magnetic electrode plate into contact with the fixed electrode.