JPH06175528A - Thermal fixing device - Google Patents

Abstract

PURPOSE:To rise the temperature of a heating roller up to the temperature suitable for heating/fixing in a short time after starting up by using an electrically heating means as a heat-generating resistor arranged on the cylindrical surface of the heating roller. CONSTITUTION:The electrically heating means includes the heat-generating resistor 21 arranged on the cylindrical surface of the heating roller 20, a brush 25 as a closee coiled contact power feeding means supplying a current to the heat-generating resistor 21 and a contact part for energization 22 being a heat- generating resistor. The outside surface of the heat-generating resistor 21 is covered with a thin protective film for releasing 23. The contact part for energization 22 is brought into contact with the heating roller 20 by the brush 25 as a contact member for supplying power. When the power of a several amperes is supplied to a resistance wire via the contact part for the energization 22, the resistance wire generates the heat with the quantity of the heat corresponding to the resistance value of the resistance wire and the protective film 23 on the surface of the heating roller 20 quickly obtains a high temperature. In other words, a heating up time is extremely short.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is used in a printing apparatus, an electrostatic copying apparatus, a facsimile receiving apparatus and the like. INDUSTRIAL APPLICABILITY The present invention is used as a device for fixing an image formed on the surface of paper or film to the surface by heating and pressing.

[0002]

2. Description of the Related Art Laser beam printers have become widespread as printing devices for office equipment equipped with computers. This device modulates and polarizes a laser beam with an input data signal, electrostatically forms a latent image on a photoconductor, forms a video by a developing machine, and transfers this video to the surface of paper,
The paper surface is heat-fixed by a heat-fixing device.
24 and 25 show the outline of the structure. FIG. 24 is a structural diagram of a laser beam printer. FIG. 25 is a block diagram of a laser beam printer. The thermal fixing device is mounted in the portion surrounded by the broken line in the figure. In addition to this laser beam printer, this principle is widely applied to electrostatic copying machines, facsimile receivers, and the like.

Next, a conventional heat fixing device will be described with reference to FIGS. 26 and 27. FIG. 26 is a configuration diagram of the pressure roller and its pressure mechanism. FIG. 27 is a block diagram of a conventional heat fixing device. As shown in FIG. 27, in the conventional thermal fixing device, the recording medium 3 such as paper or film is supplied between the heating roller 20 and the pressure roller 10 and transferred while heating the surface thereof. The image is crimped. FIG. 26 shows the pressure roller 10 and its pressure mechanism. The pressure roller 10 is composed of the shaft body 1 and the elastic layer 2,
It is attached to the support fitting 4 by a coil spring 5. The pressure roller 10 constitutes a heat fixing device together with the heating roller 20 as shown in FIG. The heating roller 20 of this conventional example device has a power consumption of 500 W and a surface temperature of 160 to 170 ° C. in a steady state.

As a heating means for the heating roller 20, a technique of arranging a halogen lamp inside the heating roller 20 is widely used. That is, in this type of conventional device, a halogen lamp is built in the heating roller 20 in a non-contact manner independently of the rotation mechanism of the roller, and the radiant heat of the halogen lamp supplies heat to the roller from the inside. This is a device with an excellent structure that allows heat to be radiated from the inside toward the surface to make the temperature distribution on the surface uniform.

[0005]

However, this conventional device has a drawback that it takes a long time to start because the halogen lamp is used. That is, it takes several minutes for the halogen lamp to reach a steady state after the device is started, and it takes 1 minute for the entire heating roller to reach an appropriate temperature for fixing.
Since it takes about 2 minutes, it takes about 5 minutes from turning on the power switch until the apparatus can be used.

For this reason, it has become general to keep the power supply of the device continuously turned on during business hours even when the device is not used. For this reason, the amount of power used becomes large, and since the device is always placed in a high temperature state, the device is inevitably consumed.

In particular, when this apparatus is used as a facsimile receiving apparatus, if the facsimile receiving apparatus starts the electric heating means of the heating roller after receiving the calling signal of the communication line, it enters the image receiving state. Since the heating is not in time by the time, in the facsimile receiving device that uses plain paper as the receiving paper, the heating roller remains set to the operating state for 24 hours, the power consumption is large and the device is in the high temperature state. Because it is maintained, its life is also shortened.

In order to shorten the start-up time, it is possible to prepare a second heating means and use the second heating means together at the time of start-up for rapid heating. However, this method requires a large current at start-up. Therefore, it is necessary to prepare the power equipment with a capacity that is several times the capacity of the steady state, or the overcurrent breaker of the power equipment operates frequently. It is not suitable as a device for easy use. Further, since the inside of the heating roller is hollow and a heat source such as a halogen lamp is arranged therein, there is a limit to downsizing of the roller diameter. In the conventional apparatus shown in FIG. 27, the heating roller 20 has a diameter of 40φ. Further, the pressure roller 10 also has a diameter of 40φ in order to correspond to it. Furthermore, in order to quickly transfer the heat from the heating element inside the heating roller 20 to the entire surface of the heating roller 20,
The material of the heating roller, including the surface thereof, must be metal, which is a good conductor of heat, and since the elastic layer 2 is provided only on the pressure roller 10, the nip width (heating roller and pressure roller Is in close contact with a recording medium such as paper and can transfer heat to the recording medium).

The present invention has been made against such a background. Even when the starting time is short, that is, even when the power supply is cut off for a long time, the heating roller is heated to a temperature suitable for heat fixing in a short time after starting. It is an object of the present invention to provide a thermal fixing device that can raise the temperature of the heating roller to a uniform value and can make the surface temperature of the heating roller uniform. In particular, in the present invention, when the heat fixing device is used for a facsimile receiving device, even if the heating roller is started after the facsimile receiving device outputs a calling signal, the heating roller is not heated at the time of executing the reception response procedure. An object of the present invention is to provide a heat fixing device that can be activated in a short time so that it can be sufficiently made. INDUSTRIAL APPLICABILITY According to the present invention, the power supply current can be cut off when not in use, the amount of power used can be reduced, the life of the device can be lengthened, and further, the size and size of the thermal fixing device can be reduced and the cost can be reduced. The purpose is to provide. A further object of the present invention is to provide a device capable of increasing the nip width between the heating roller and the pressure roller, and capable of executing practically effective thermal fixing even at a low temperature.

[0010]

According to the present invention, there is provided a heating roller provided with an electric heating means, a rotating shaft of the heating roller and a pressure roller arranged so that the rotating shaft is parallel to each other, In a thermal fixing device including a pressing unit that applies a force in a direction of reducing the distance between the rotation axes of the rollers, and a unit that supplies a recording medium between the two rollers, the electrical heating unit includes the heating roller. It is characterized in that it includes a heating resistor arranged on the cylindrical surface and a contact feeding means for supplying a current to the heating resistor.

Further, it is desirable that the outer surface of the heating resistor is covered with a thin protective film. Further, the heating roller includes a cylindrical shaft body and an insulating layer formed on the surface of the shaft body, and the heating resistor is a resistance wire mounted on the insulating layer or a film-like shape. It is also possible to have a structure formed in. It is desirable that the heating resistor is set so that the current density flowing inside the heating resistor becomes dense in the vicinity of the shaft end portion in the axial direction of the heating roller. Further, the heating roller may include an elastic layer between the shaft body and the surface. Further, the contact power supply means may be configured to include a conductor ring formed at both ends of the heating roller and a brush in contact with the ring.

[0012]

Since the heating resistor is arranged on the surface of the heating roller, it is not necessary to raise the temperature of the entire roller to a high temperature, and the heat capacity of the portion to be heated at the time of starting is extremely small. Therefore, it is possible to heat to a steady temperature in a short time with a small amount of electric power.

By covering the outer surface of the heating resistor with a thin protective film, the recording medium and the heating resistor do not come into direct contact with each other, so that the mechanical wear of the heating resistor is reduced and the service life is extended. By setting the density of the heating resistor, to be more precise, the current density in the axial direction flowing through the heating resistor to be large in the vicinity of the shaft end, the temperature at the shaft end becomes low and uneven fixing occurs. Can be avoided.

Since it is not necessary to conduct heat from the inside of the heating roller, a mechanical elastic layer can be provided between the shaft and the surface of the heating roller to impart elasticity to the surface of the heating roller. Therefore, the nip width that comes into contact with the recording medium can be made larger between the pressure roller that has an elastic layer in advance, and substantially effective heat fixing can be performed even if the surface temperature of the heating roller is low. can do.

In the case where the heating element is a halogen lamp, if the supply current is temporarily cut off, the operation is stopped and it takes time to restart. However, in the present invention, the heating element is Since is an electric resistor, its temperature does not change even if the current is interrupted. Therefore, even if conductor rings are provided at both ends of the heating roller and a brush in contact with this ring is used to supply the current required for heating by contact, there is almost no effect due to instantaneous interruption of the current.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a side view of the first embodiment device of the present invention. FIG. 2 is a top view of the essential parts of the device of the first embodiment of the present invention. FIG. 3 is a vertical cross-sectional view of the heating roller of the first embodiment device of the present invention.

According to the present invention, a heating roller 20 provided with an electric heating means, a pressure roller 10 arranged such that the rotation axis of the heating roller 20 is parallel to the rotation axis, and rotation of these two rollers. In the thermal fixing device, which is provided with a coil spring 5 as a pressurizing means for applying a force in the direction of reducing the axial distance and a recording medium supply guide 6 as a means for supplying the recording medium 3 between the two rollers, The electric heating means includes a heating resistor 21 arranged on the cylindrical surface of the heating roller 20, a brush 25 as a contact power feeding means for supplying a current to the heating resistor 21, and a closely wound heating resistor. It is characterized by including a certain energizing contact portion 22. In addition, the outer surface of the heating resistor 21 is covered with a thin protective film 23 for release. Further, the heating roller 20 includes a cylindrical shaft body 1 and an insulating layer 24 formed on the surface of the shaft body 1, and the heating resistor 21 is a resistance wire mounted on the insulating layer 24. It is configured. The shaft body 1 is formed of stainless steel having high bending rigidity. The insulating layer 24 is made of Teflon. Also,
The resistance wire of the heating resistor 21 is formed to have a circular cross section by extending a heating long resistor of nickel-chromium alloy to have a diameter of about 0.1 to 0.5 mm.
It is wound so as to form a spiral of equal diameter with respect to the center of the. The winding pitch of the resistance wire is set to the heating roller 20.
The resistance value of the resistance wire (proportional to length ÷ cross-sectional area) is determined according to the amount of heat required (current × resistance value ² ), so the length of the resistance wire and the diameter of the heating roller 20 Although it is determined according to this, it is appropriately adjusted so that the temperature distribution in the axial direction of the heating roller 20 becomes uniform. The protective film 23 is formed as a flexible heat resistant film by applying Teflon thinly and drying it. The protective film 23 prevents the toner, which is the fixing target, from adhering to the heating roller 20, and also serves as an insulating film.

Next, the operation of the heat fixing device and its heating roller 20 according to the first embodiment of the present invention will be described with reference to FIGS. FIG. 4 shows the heating roller 20 of the first embodiment device of the present invention.
3 is a side sectional view of the pressure roller 10. FIG. FIG. 5 is a view showing a mounting state of the pressure roller 10 on the support fitting 4. FIG. 6 is an outside diameter dimension diagram of the device of the first embodiment of the present invention. FIG. 7 is a perspective view showing a brush mounted state of the first embodiment device of the present invention. FIG. 8 is a diagram showing a recording medium and an object to be fixed. Figure 4
As shown in FIG. 1, the pressure roller 10 in which the elastic layer 2 is applied to the heating roller 20 in a layer thickness on the shaft body 1 is shown in FIGS.
Is arranged so as to be in pressure contact with each other by a pressing mechanism by a coil spring 5 as shown in FIG.
Nip width X, which is a heating region, is set by the elasticity of the.

The heating roller 20 and / or the pressure roller 10 are rotationally driven by a drive source (not shown). Further, the heating roller 20 has a contact point 2 for energization, which is a closely-wound heating resistor for energizing both ends.
As shown in FIG. 7, the brush 2 is a contact member for power supply.
5, the heating resistor 21 is supplied with power through the energizing contact portion 22. Heat is conducted from the energizing contact portion 22 to the brush 25, so that the temperature distribution of the heating roller 20 has a temperature gradient that becomes lower at both ends. This temperature gradient is compensated by making the winding pitch closer to both ends. When the resistance wire is energized through the energizing contact portion 22 by about several amperes, the resistance wire generates heat with an amount of heat corresponding to the resistance value, and the protective film 23 on the surface of the heating roller 20 is quickly heated to a high temperature. Become. That is, the heat-up time is extremely short. From this state, as shown in FIG. 8, when the recording medium 3 such as paper having toner adhered to the surface is fed between the heating roller 20 and the pressure roller 10 which rotate at a constant peripheral speed while being pressed. At the same time, the heating roller 20 contacts the surface of the recording medium 3 to heat-melt the toner, and at the same time, the heat-melted toner is pressed by the uniform contact pressure from the pressure roller 10 to ensure the surface of the recording medium 3. Is fixed in.

The recording medium 3 on which the toner is fixed is sent out of the heat fixing device as the heating roller 20 and the pressure roller 10 rotate. The first embodiment of the present invention can be realized with the dimensions shown in FIG. When compared with the size of the conventional device shown in FIG. 27, which has already been described, it can be seen that the size has been dramatically reduced. Such miniaturization can be realized by providing the heat source on the surface of the heating roller 20, which is conventionally provided inside the heating roller 20.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 9 shows the heating roller 2 of the second embodiment device of the present invention.
It is a longitudinal cross-sectional view of 0. A feature of the second embodiment of the present invention is that the shaft body 1 made of stainless steel having high bending rigidity is used.
Is to have an elastic layer 2 which is formed to have a smaller diameter and which is attached to the peripheral surface in a layer thickness. The elastic layer 2 is formed of the same material as the elastic layer 2 of the pressure roller 10, and is formed by molding a silicon-based heat resistant elastomer material. The characteristics of this elastic layer 2 are rubber hardness (A scale) 4
It was set to about 0 to 80 °.

As an advantage of the second embodiment of the present invention, the basic operation of the heat fixing device and the heating roller 20 is the same as that of the first embodiment of the present invention, but the heating roller 20 is also provided with the elastic layer 2. Therefore, as compared with the first embodiment of the present invention, the contact area between the heating roller 20 and the pressure roller 10 is expanded, and the nip width X can be further increased. Further, since the shaft body 1 is already electrically insulated by the elastic layer 2, the insulating layer 24 may be omitted.

Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 10 is a vertical cross-sectional view of the heating roller 20 of the third embodiment device of the present invention. The feature of the third embodiment of the present invention is that
The shaft body 1 is made of synthetic resin, and the heating resistor 21 is not a resistance wire but a resistance band having a rectangular cross section. As the material for the shaft body 1, polyphenylene sulfide, which is a synthetic resin having high bending rigidity, was used. The resistance band is formed by extending and rolling a long resistor of nickel-chromium alloy so as to have a rectangular cross section, and is wound so as to have a spiral shape having an equal diameter with respect to the center of the shaft body 1.

The winding pitch of this resistance band is set so that the temperature distribution in the axial direction of the heating roller 20 becomes uniform as already described. This resistance band is tightly wound, and the energizing contact portions 22 that are tightly wound heating resistors are provided at both ends of the shaft body 1 as in the case of the resistance wire.

An advantage of the third embodiment of the present invention is that the resistance of the heating resistor 21 is changed from a resistance wire to a resistance band, and therefore the unevenness of the protective film 23 on the surface of the heating roller 20 is further improved as compared with the case where a resistance wire is used. This is a point that can be reduced. Further, since the shaft body 1 is made of synthetic resin and is an insulator, the insulating layer 24 is unnecessary, and the number of manufacturing steps can be reduced.

Next, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 11 is a vertical sectional view of the heating roller 20 of the fourth embodiment device of the present invention. The features of the fourth embodiment of the present invention are:
The shaft 1 made of synthetic resin shown in the third embodiment of the present invention, which uses a resistance band instead of the resistance wire, is formed to have a small diameter, and the elastic layer 2 is provided on the peripheral surface thereof.

The advantage of the fourth embodiment of the present invention is that the heating roller 20 and the pressure roller 1 are the same as in the second embodiment of the present invention.
Since the elastic layer 2 is provided on both sides of the shaft 0, the nip width X can be increased, and the shaft body 1 and the elastic layer 2 are both insulators as in the case of the third embodiment of the present invention. 24 is unnecessary, and the number of manufacturing steps can be reduced.

Next, a fifth embodiment of the present invention will be described with reference to FIGS. FIG. 12 is a plan view of the heating roller 20 of the fifth embodiment device of the present invention. FIG. 13 is a side sectional view of the heating roller 20 and the pressure roller 10 of the device of the fifth embodiment of the present invention. As shown in FIG. 12, the fifth embodiment of the present invention is characterized in that the resistance wire forming the heating resistor 21 is arranged so as to meander along the longitudinal direction of the heating roller 20, and the contact portion 22 for energization is provided. That is, a conductive metal ring made of aluminum was used in place of the heat-generating resistor that was tightly wound.

The advantage of the fifth embodiment of the present invention is that the resistance wire is meandered along the longitudinal direction of the heating roller 20,
Compared to the case where the resistance wire is spirally wound, the heating roller 20
The deformation rate that the resistance wire receives when elastically deformed under high pressure can be reduced. Further, by replacing the energizing contact portion 22 with a conductive metal ring, the surface of the energizing contact portion 22 becomes smooth, and the contact resistance with the power feeding brush 25 can be reduced. Further, here, in order to reduce the unevenness of the protective film 23, the resistance wire is formed to have an elliptical cross section.

Next, a sixth embodiment of the present invention will be described with reference to FIG. FIG. 14 is a side sectional view of the heating roller 20 of the sixth embodiment device of the present invention. The characteristics of the sixth embodiment of the present invention are:
This means that the shaft 1 in the fifth embodiment of the present invention has a small diameter and the elastic layer 2 is provided on the peripheral surface thereof.

The advantage of the sixth embodiment of the present invention is that, in addition to the advantages of the fifth embodiment of the present invention, the heating roller 20 also has the elastic layer 2 together with the elastic layer 2 of the pressure roller 10, so that the nip width X
Is to spread.

Next, a seventh embodiment of the present invention will be described with reference to FIG. FIG. 15 is a side sectional view of the heating roller 20 of the seventh embodiment device of the present invention. The features of the seventh embodiment of the present invention are:
The point is that a thin film resistor is used as the heating resistor 21. A nickel chrome alloy is vapor-deposited on the peripheral surface of the elastic layer 2 to form a thin film resistor foil as the heating resistor 21, and a protective film 23 is applied thereon. Further, the protective film 23 is removed only on both ends of the heating roller 20, and this is used as the energizing contact portion 22.

The advantage of the seventh embodiment of the present invention is that there is no unevenness on the surface due to the resistance wire or the resistor, and there is no break in the heating element, so it is suitable for uniforming the temperature distribution. Further, the processing of the energizing contact portion 22 can be simplified.

Next, an eighth embodiment of the present invention will be described with reference to FIG. FIG. 16 is a plan view of the heating roller 20 of the device of the eighth embodiment of the present invention. The eighth embodiment of the present invention is characterized in that a thin film resistor is used as the heating resistor 21 as in the seventh embodiment of the present invention, but the surface temperature of the heating roller 20 when the thin film resistor is energized. Corresponding to the temperature gradient obtained by measuring the distribution, the pitch of the band of the thin film resistor formed by forming the groove 27 on the surface of the thin film resistor is changed.
In the seventh embodiment of the present invention, the heating resistor 21 has no gap,
Although it looks ideal to make the temperature distribution uniform,
In order to actually make the temperature distribution uniform, it is necessary to control the homogeneity of the material by extremely strict quality control in the process of manufacturing the thin film resistor used for it.
Further, even if the thin film resistor is uniform, a temperature gradient is generated depending on the mounting state of the heating roller 20 for the reason already explained. Therefore, an advantage of the eighth embodiment of the present invention is that the "unevenness" in the temperature distribution of the heating roller 20 can be compensated by changing the pitch of the strip of the thin film resistor formed by the groove 27.

Next, a ninth embodiment of the present invention will be described with reference to FIG. FIG. 17 is a vertical sectional view of the heating roller 20 of the ninth embodiment device of the present invention. The features of the ninth embodiment of the present invention are:
That is, the elastic layer 2 itself is used as the heating resistor 21. The elastic layer 2 is formed of a material formed by dispersing conductive carbon in a silicon-based synthetic resin. The characteristics of the conductive elastic layer 2 are that the specific resistance value is 100 Ωcm or less, the resistance value between both end surfaces is 1000 Ω or less, and the rubber hardness A scale is 40 to 8
It is about 0 °. The diameter near both ends of the elastic layer 2 is processed to be small, and a conductive metal ring is fitted therein to form the energizing contact portion 22.

An advantage of the ninth embodiment of the present invention is that since the elastic layer 2 itself forms the heating resistor 21, no obstacle such as a disconnection of the resistance wire occurs due to the elasticity change.

Next, a tenth embodiment of the present invention will be described with reference to FIG. FIG. 18 is a vertical sectional view of the heating roller 20 of the device according to the tenth embodiment of the present invention. The features of the tenth embodiment of the present invention are:
It is the shape of the energizing contact portion 22. The energizing contact portion 22 is formed by sandwiching the elastic layer 2 from both sides with a circular metal plate having a hole through which the shaft body 1 penetrates at the center portion.

The advantage of the tenth embodiment of the present invention is that since the elastic layer 2 can be formed as a column having a uniform diameter, the man-hours for processing the elastic layer 2 can be reduced, and the energizing contact portion 22.
Since the mounting of can be simplified, the number of assembling steps can be reduced.

19 and 20 are vertical sectional views of the heating roller 20 having a large diameter. Needless to say, it can be formed to have a large diameter as shown in FIG.
As shown in FIG. 20, a part of the inside of the shaft body 1 may be hollow to reduce the weight.

FIG. 21 is a view showing a mounted state of the brush 25, but the structure shown in FIG. 21 may be adopted in addition to the structure of the brush 25 shown in FIG.

As the material for forming each part, in addition to the materials described in the above embodiments, the shaft body 1 is aluminum, and the synthetic resin shaft body 1 is polysulfone, aromatic polyamide, aromatic polyester, Polyamide imide, insulating layer 2
4, a synthetic resin of silicon, an inorganic temperature insulating material of ceramic paper, a protective film 23, coating of silicon, coating of a silicon tube, an elastic layer 2 of tetra-fluoro-ethylene-propylene-based, vinylidene fluoride-based, Fluorine-based, conductive elastic layer 2 such as silicon-based or fluoro-silicon-based is used as a heat-resistant elastomer material such as tetra-fluoro-ethylene-propylene-based, vinylidene fluoride-based, silicon-based, fluoro-silicon-based, etc. Conductive carbon, conductive inorganic powder, conductive potassium titanate whiskers are dispersed. The contact point 22 for electricity is steel, metal ring made of brass, conductive resin coating, metal sputtering or vapor deposition, conductive resin made. The ring and the thin film resistor are made by depositing nickel chrome alloy on a plastic film, It is fitted. Alternatively, as the rubber / plastic-based conductive film, a cylindrical plastic film in which powdered metal-based conductive material or carbon-based conductive material is compounded is fitted on the peripheral surface of the elastic layer, or powdered metal-based conductive material or A flexible conductive film such as a coating material containing a carbon-based conductive material applied on the peripheral surface of the elastic layer and dried is used. It can also be formed by, for example.

Next, the effects of the first to tenth embodiments of the present invention will be described with reference to FIGS. 22 and 23. FIG. 22 is a diagram showing the temperature rise characteristics obtained by averaging the first to tenth embodiments of the present invention. FIG. 23 is a diagram showing current characteristics obtained by averaging the first to tenth embodiments of the present invention. FIG. 22 shows the temperature rise characteristics as an effect obtained by averaging the first to tenth embodiments of the present invention. It can be seen that the set temperature is reached about four times faster than in the conventional example. Moreover, the current characteristics are shown in FIG. 23 as an effect obtained by averaging the first to tenth embodiments of the present invention. As compared with the conventional example, the current value is about 1/15 for the inrush current and about 1/10 for the steady current.

[0043]

As described above, according to the present invention,
Even when the start-up time is short, that is, the power is cut off for a long time, the heating roller can be heated to a temperature suitable for heat fixing in a short time after start-up, and
The surface temperature of the heating roller can be made uniform. In particular, when the heat fixing device is used as a facsimile receiving device, even if the heating signal is output from the facsimile receiving device and then the heating roller is started, the heating roller is sufficiently heated in the time for executing the reception response procedure. It can be activated in a short time. Further, the power supply current can be cut off during the non-use time, the amount of power used can be reduced, and the device life can be extended. Further, the device itself can be downsized, and the structure can be simple and inexpensive. Further, the nip width between the heating roller and the pressure roller can be made large, and practically effective thermal fixing can be performed even at a low temperature.

[Brief description of drawings]

FIG. 1 is a side view showing the main configuration of a device according to a first embodiment of the present invention.

FIG. 2 is a partial top view showing the configuration of the main part of the device according to the first embodiment of the present invention.

FIG. 3 is a vertical cross-sectional view of a heating roller of the first embodiment device of the present invention.

FIG. 4 is a side sectional view of a heating roller and a pressure roller of the first embodiment device of the present invention.

FIG. 5 is a view showing a mounting state of a pressure roller to a support fitting.

FIG. 6 is a view showing the outer diameter dimension of the first embodiment device of the present invention.

FIG. 7 is a diagram showing a state where a brush of the device of the first embodiment of the present invention is attached.

FIG. 8 is a diagram showing a recording medium and an object to be fixed.

FIG. 9 is a vertical cross-sectional view of a heating roller of a second embodiment device of the present invention.

FIG. 10 is a vertical cross-sectional view of a heating roller of a third embodiment device of the present invention.

FIG. 11 is a vertical cross-sectional view of a heating roller of a fourth embodiment device of the present invention.

FIG. 12 is a plan view of a heating roller of a fifth embodiment device of the present invention.

FIG. 13 is a side sectional view of a heating roller and a pressure roller according to a fifth embodiment of the present invention.

FIG. 14 is a side sectional view of a heating roller of an apparatus according to a sixth embodiment of the present invention.

FIG. 15 is a vertical cross-sectional view of a heating roller of a seventh embodiment device of the present invention.

FIG. 16 is a plan view of a heating roller of a device of an eighth embodiment of the present invention.

FIG. 17 is a vertical cross-sectional view of a heating roller of a ninth embodiment device of the present invention.

FIG. 18 is a vertical sectional view of a heating roller of an apparatus according to the tenth embodiment of the present invention.

FIG. 19 is a vertical sectional view of a heating roller having a large diameter.

FIG. 20 is a vertical cross-sectional view of a heating roller having a large diameter.

FIG. 21 is a view showing a state where a brush is attached.

FIG. 22 is a diagram showing temperature rising characteristics obtained by averaging the first to tenth embodiments of the present invention.

FIG. 23 is a diagram showing average current characteristics of the first to tenth embodiments of the present invention.

FIG. 24 is a structural diagram of a laser beam printer.

FIG. 25 is a block diagram of a laser beam printer.

FIG. 26 is a configuration diagram of a pressure roller and its pressure mechanism.

FIG. 27 is a configuration diagram of a conventional thermal fixing device.

[Explanation of symbols]

 1 Shaft 2 Elastic Layer 3 Recording Medium 4 Supporting Metal 5 Coil Spring 6 Recording Medium Supply Guide 10 Pressure Roller 20 Heating Roller 21 Heating Resistor 22 Energizing Contact 23 Protective Film 24 Insulating Layer 25 Brush 26 Lead Wire 27 Groove X Nip width

Claims (7)

[Claims] 1. A heating roller provided with an electric heating means,
Between the rotation axis of the heating roller and the pressure roller arranged so that the rotation axis is parallel to each other, pressure means for applying a force in a direction to reduce the distance between the rotation axes of the two rollers, and between the two rollers. In the thermal fixing device including a means for supplying a recording medium, the electric heating means includes a heating resistor arranged on the cylindrical surface of the heating roller, and a contact for supplying a current to the heating resistor. A thermal fixing device comprising: a power supply unit. 2. The heat fixing device according to claim 1, wherein a thin protective film is provided on the outer surface of the heating resistor. 3. The heating roller includes a cylindrical shaft body and an insulating layer formed on a surface of the shaft body, and the heating resistor is a resistance wire mounted on the insulating layer. Item 2. A heat fixing device according to item 2. 4. The heating roller includes a cylindrical shaft body and an insulating layer formed on a surface of the shaft body, and the heating resistor is formed in a film shape on the insulating layer. The heat fixing device as described in 1 or 2. 5. The heat fixing device according to claim 1, wherein the heat generating resistor is set such that a current density flowing through the heat generating resistor becomes dense in the vicinity of a shaft end portion in the axial direction of the heating roller. apparatus. 6. The heat fixing device according to claim 1, wherein the heating roller includes an elastic layer between the shaft body and the surface. 7. The heat fixing device according to claim 1, wherein the contact power supply unit includes a ring of a conductor formed at both ends of the heating roller, and a brush in contact with the ring.