JP2003036964A - Induction heating roller device, fixing device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an induction heating roller device provided with a heating roller in which the resistance value is managed as a prescribed value in an empty core transformer coupling method, and provide a fixing device and an image forming device provided with this. SOLUTION: The induction heating roller device has a heating roller HR provided with the first metal coating film ws to form the secondary coil of a closed circuit wherein the secondary current flows mainly in the peripheral direction to generate heat as the film is arranged and installed at the surface of the roller substrate 1 and air-core transformer coupled to the postscript induction coil, and provided with the second oxidation resistant metal coating film ns to cover the surface of the first metal coating film ws, and has the induction coil arranged and installed by being wound around in the periphery of the shaft in the inside of the heating roller HR. The structure of the heating roller HR is simple, and superior in durability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction heating roller device, a fixing device including the induction heating roller device, and an image forming apparatus.

[0002]

2. Description of the Related Art In order to thermally fix a toner image, a heating roller using a halogen bulb as a heat source has been conventionally used, but it is inefficient and requires a large amount of electric power. Therefore, development is being carried out to introduce the induction heating method to solve this problem.

Japanese Patent Laid-Open No. 2000-215974 discloses that
An exciting coil, which is arranged close to a heated body and generates an induced current in a heating roller made of a magnetic material, which is a heated body, is a coil wire wound in a plane. Described is an exciting coil that is deformed along a curved surface and has a magnetic core arranged along the curved surface of the exciting coil on the side opposite to the heated body at both ends in the longitudinal direction of the exciting coil. . (Prior Art 1) Japanese Unexamined Patent Publication No. 2000-215971 has a heating rotating body, that is, a heating roller, having an electromagnetic induction heat generating property, and a magnetic flux generating means disposed inside the heating rotating body. An induction heating device that heats an object to be heated by electromagnetically heating a heating rotating body by the generated high-frequency induction magnetic flux, wherein the magnetic flux generating means includes a core made of a magnetic material and an electromagnetic conversion coil wound around the core. The magnetic core has a magnetic flux that is opposed to the core part around which the electromagnetic conversion coil is wound, and a magnetic space gap between the tips to concentrate the magnetic flux from the core part to a part of the heating rotor. A structure having an inductive core portion is described. (Prior Art 2) Both of the prior arts 1 and 2 are heating methods utilizing eddy current loss (hereinafter referred to as "eddy current loss method").
The operating principle is the same as that put to practical use in H jars and the like. The frequency of the high frequency used in the eddy current loss method is about 20 to 100 kHz.

On the other hand, Japanese Patent Laid-Open No. 59-33787 discloses a cylindrical roller body made of a conductive member, that is, a heating roller, a cylindrical bobbin concentrically arranged in the roller body, and an outer circumference of the bobbin. , A high-frequency induction heating roller provided with an induction coil that is spirally wound and induces an induction current in the roller body by energization to heat the same. (Prior Art 3) In the prior art 3, the cylindrical roller body has a closed circuit of 2
It becomes the secondary coil, the induction coil becomes the primary coil, and transformer coupling occurs between the two, and
A secondary voltage is induced in the secondary coil. Then, based on this secondary voltage, a secondary current flows in the closed circuit of the secondary coil, so that the cylindrical roller body generates heat, and the secondary side resistance generates heat (hereinafter referred to as a "transformer method"). )
Is. The transformer method has a higher magnetic coupling than the eddy current loss method, so that the steady efficiency is high, and the entire heating roller can be heated. Therefore, the structure of the fixing device is simpler than those of the prior arts 1 and 2. is there. In addition, by setting the operating frequency to a high frequency of 100 kHz or higher, preferably 1 MHz or higher, the Q of the induction coil can be increased and the power transfer efficiency can be increased. Therefore, the overall efficiency of heating is increased, and power saving can be achieved. There is also an advantage that the structure of the fixing device is simpler than that of the eddy current loss method. Further, the heat capacity can be made considerably smaller than that of the eddy current loss type heating roller. Therefore, the transformer method is very suitable for speeding up heat fixing.

The inventors of the present invention first form a closed circuit having a secondary side resistance value of a heating roller having a hollow structure rotatably supported by an air core transformer coupled to an induction coil and having a secondary reactance substantially equal to the secondary reactance. As a result, the efficiency of electric power transmission from the induction coil to the heating roller is increased, and the invention of the transformer coupling type is obtained in which the remarkable effect that the heating roller can be efficiently heated is obtained. This invention is disclosed in Japanese Patent Application No. 2001-016.
No. 335 has been filed by the applicant. According to the present invention, it is possible to save the electric power for the induction heating of the heating roller and speed up the heat fixing.

[0006]

However, in the air-core transformer coupling method, a heating roller whose resistance value is controlled to a predetermined value as described above is produced on an industrial scale and at low cost, and the heating roller is The technology for easy mounting on equipment has not been established.

Further, it is necessary to appropriately maintain the temperature distribution of the heating roller regardless of the presence or absence of a heat load, but the temperature control technology of the heating roller in the air core transformer coupling system has not been established.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an induction heating roller device including a heating roller whose resistance value is controlled to a predetermined value in an air-core transformer coupling system, a fixing device including the heating roller device, and an image forming apparatus. To do.

Still another object of the present invention is to provide an induction heating roller device configured to appropriately maintain the temperature distribution of the heating roller in the air-core transformer coupling method, a fixing device including the induction heating roller device, and an image forming apparatus. The purpose of.

Another object of the present invention is to provide an induction heating roller device which facilitates mounting on an apparatus in an air-core transformer coupling system, a fixing device and an image forming apparatus having the induction heating roller device.

[0011]

According to the induction heating roller device of the present invention, the secondary current is mainly circulated by being provided on the surface of the roller base body and the roller base body and coupled to the induction coil by an air core transformer. A first metal coating forming a closed-circuit secondary coil that flows in a direction to generate heat, and a heating roller having an oxidation-resistant second metal coating covering the surface of the first metal coating; And an induction coil wound around the axis inside the roller.

In the present invention and the following respective inventions, the definitions and technical meanings of terms are as follows unless otherwise specified.

<Regarding Heating Roller> The heating roller comprises a roller base, a first metal coating and a second metal coating.

The roller base body is made of a metal or a heat resistant insulator. If metal is heat resistant and has high mechanical strength,
Any metal may be used with or without conductivity.
However, Fe or Al is preferable in terms of workability and cost. Even if the roller base body is made of both conductive metals, if the secondary side resistance value is a value greatly different from the secondary reactance, high frequency power is substantially transmitted from the induction coil to the roller base body. There is no such thing. The heat-resistant insulator may be any insulator as long as it has heat resistance and high mechanical strength. However, it is preferably ceramics or glass. As ceramics,
For example, alumina, mullite, aluminum nitride and silicon nitride. Examples of the glass include crystallized glass, quartz glass and Pyrex (registered trademark)
And so on.

The first metal coating is provided on the surface of the roller base. Then, a secondary coil of a closed circuit is formed, and this secondary coil is coupled to the primary coil by an air-core transformer. The resistance value of the secondary side of the closed circuit is 2
It preferably has a value approximately equal to the secondary reactance. The expression "equal to the secondary side resistance value and the secondary reactance" means that when the secondary side resistance value is Ra, the secondary reactance is Xa, and α = Ra / Xa, The range can be satisfied. Further, the secondary side resistance value can be obtained by measurement. The secondary side reactance can be calculated.

[0016]

0.25 <α <4 Further, the heating roller can be arranged so that the secondary coil has a single or plural form. In the case of a single secondary coil, it is desirable to arrange the secondary coil so as to extend over almost the entire effective length along the axial direction of the heating roller. Further, when a plurality of secondary coils are arranged, it is desirable to disperse them in the axial direction of the heating roller.

Further, for the first metal film forming the secondary coil, the following materials and manufacturing methods can be adopted in order to obtain a desired secondary side resistance value. Electroplating,
When forming by vapor deposition or sputtering,
It is preferable to use a material selected from the group of Cu, Ni, Ag and Al. On the other hand, when the film is formed by the thick film forming method (coating + baking), Cu, Ag and A
It is preferable to use a material selected from the group consisting of g + Pd. As a coating method, a screen printing method, a roll coater method, a spray method or the like can be used. However, the most industrially mass-producible and inexpensive method is to form the first metal film by Cu electroplating.

Next, the second metal coating is made of a metal having oxidation resistance and covers the surface of the first metal coating. That is, the second metal coating protects the surface of the first metal coating and prevents oxidation. It should be noted that “having oxidation resistance” means that the oxidation of the first metal film can be substantially prevented, and therefore the surface may be oxidized. Suitable metals include Zn, Sn, Ni and Ti, and the second metal film can be formed by electroplating, vapor deposition, sputtering, thick film forming method and the like. However, the most industrially mass-producible and inexpensive method is to form the second metal coating by electroplating Zn.

Further, the first and second metal coating films are
It can be disposed on either or both of the outer and inner surfaces of the roller base. Further, the first and second metal coatings may be composed of a plurality of layers.

In order to obtain a more practical heating roller, it is permissible to add the following configuration as required.

1 Protective Layer The protective layer may be provided as necessary for mechanical protection and electrical insulation of the heating roller, or for improving elastic contact property or toner releasability. Glass can be used as the constituent material of the protective layer for the former, and synthetic resin can be used as the constituent material of the protective layer for the latter. As the glass, zinc borosilicate glass,
It can be selected from the group consisting of lead borosilicate glass, borosilicate glass and aluminosilicate glass. The latter can be selected from the group consisting of silicone resin, fluorine resin, polyimide resin + fluorine resin and polyamide + fluorine resin. In addition, polyimide resin +
In the case of the fluororesin and polyamide + fluororesin, the fluororesin is disposed on the outside.

2 Regarding the shape of the heating roller If desired, a crown can be formed on the heating roller. The crown may have either a drum shape or a barrel shape.

3 Rotating Mechanism of Heating Roller A known mechanism can be appropriately selected and employed as a mechanism for rotating the heating roller.

4 Temperature Sensor In order to control the temperature of the heating roller, the temperature sensor can be thermally conductively contacted in place on the heating roller. When a plurality of induction coils are arranged dispersedly in the axial direction of the heating roller, a plurality of temperature sensors can be arranged so as to be sensitive to the temperature of the position facing each induction coil. Then, by controlling the electric power supplied from the induction coil according to the temperature of the axial region, it is possible to improve the temperature uniformity of the heating roller.

<Induction coil> A single induction coil or a plurality of induction coils are wound around the axis inside the heating roller. When using multiple induction coils,
Multiple induction coils can be connected in parallel or series to a single high frequency power supply. Further, if a plurality of induction coils are connected to respective high frequency power sources, it becomes possible to adjust the input power individually or in groups. Furthermore, when using a plurality of induction coils, it is preferable to disperse them in the axial direction. In this case, an appropriate space may be provided between the adjacent induction coils, or if there is no problem with insulation, they may partially overlap each other. When the induction coil is energized, that is, excited by a high-frequency power source, it generates a magnetic field, and the magnetic field interlinks with the secondary coil of the heating roller and flows in the secondary coil mainly in the circumferential direction of the heating roller. The next current is generated. That is, the induction coil and the secondary coil function as the primary coil and the secondary coil of the transformer via the high-frequency AC magnetic field. At this time, both perform air core transformer coupling. It should be noted that even if an eddy current is generated in the secondary coil when a part of the magnetic flux passes through the secondary coil, it does not matter if most of the secondary current flows in the circumferential direction.

Therefore, the induction coil is a means for transferring high frequency power to the secondary coil of the heating roller.
For that purpose, the induction coil is inserted inside the hollow heating roller, but the one acting as the core is not used. The induction coil may be stationary with respect to the rotating heating coil, or together with the heating roller,
Alternatively, it may be rotated separately. In addition, when rotating,
A rotary current collecting mechanism may be interposed between the high frequency power source and the induction coil. Further, the "air-core transformer coupling" is meant to include not only a complete air-core transformer coupling but also a transformer coupling that can be regarded as a substantially air-core. For example, the induction coil does not have a magnetic material inside.

<Regarding Other Configurations> Although not an essential component of the present invention, a more effective induction heating roller device can be obtained by selectively implementing the following configurations as desired.

In order to maintain the predetermined shape and position of the induction coil for one reel, it is possible to support the induction coil by using a reel made of a material with as little dielectric loss as possible. . In this case, the bobbin may be hollow or may be solid inside. A winding groove for aligned winding and an axial groove for accommodating the feeding lead wire can be formed in the winding frame. However, instead of the bobbin, the induction coils may be directly molded or adhered with a synthetic resin or a glass material to maintain the plurality of induction coils in a predetermined shape.

Regarding the power supply lead wire, a power supply lead wire can be used for supplying high frequency power from the high frequency power supply to the induction coil, or in addition to this, for connecting to the capacitor. The power supply lead wire is preferably arranged at a position close to the inner surface or the outer surface of the induction coil. When the power supply lead wire is passed inside the induction coil, if the power supply lead wire is close to the center axis of the induction coil, the magnetic flux interlinking with the power supply lead wire will increase, resulting in eddy current loss inside the power transfer. This is not preferable because it lowers efficiency. On the other hand, by configuring as described above,
Since the magnetic flux interlinking with the power supply lead wire is reduced, the decrease in power transmission efficiency is relatively suppressed.

3. Capacitor in parallel with induction coil A capacitor can be connected in parallel with the induction coil. The capacitor forms a resonant circuit with the induction coil. In this case, the position where the capacitor is provided is not particularly limited. If the heat resistant temperature of the condenser and the space inside the heating roller are allowed, it may be placed inside the heating roller close to the induction coil, or the condenser may be placed away from the induction coil and heating roller. Good.

4. Regarding High Frequency Power Supply The output frequency of the high frequency power supply is basically not limited, but it is convenient if it is configured to output a high frequency of 100 kHz or higher. Because 100
By setting the high frequency above kHz, the induction coil Q
This is because it is possible to further increase the power transmission efficiency by increasing When the power transmission efficiency is high, the overall efficiency of heating is high, and power can be saved. Note that compatible active devices (eg MOSF as described below)
ET can be used. From the viewpoints of economy and ease of suppressing high frequency noise, etc., 1 to 4 MH is preferable.
z.

To generate a high frequency, it is practical to directly or indirectly convert a direct current or a low frequency alternating current into a high frequency by using an active element such as a semiconductor switch element. In order to obtain high frequency power from the low frequency alternating current, it is preferable to convert the low frequency alternating current into direct current by using a rectifying means. The direct current may be a smoothed direct current formed by using a smoothing circuit or may be a non-smoothed direct current. Circuit elements such as an amplifier and an inverter can be used to convert direct current into high frequency. As the amplifier, for example, a class E amplifier having high power conversion efficiency can be used. Also, a half-bridge type inverter or the like can be used. Furthermore, as the active element, a MOSFET having excellent high frequency characteristics is suitable. A plurality of high frequency power supply circuits may be connected in parallel, and the high frequency outputs of the respective high frequency power supply circuits may be combined and then applied to the induction coil. As a result, the output of each high-frequency power supply circuit may be small even with the desired power, so that a high frequency can be efficiently generated at low cost by using a MOSFET as an active element.

Further, when using a plurality of induction coils,
The high frequency power supply can be common to a plurality of induction coils. Further, by variably configuring the output frequency of the high frequency power source, it becomes possible to individually control the electric power supplied to each induction coil. However, if necessary, a high-frequency power source with variable frequency can be separately provided for each induction coil.

Furthermore, if necessary, for example, the input power at the time of start-up can be made larger than that at the time of normal operation, so that the rapid heating can be performed.

5 Warm-up Control During the warm-up period after startup, that is, after power supply is started, the heating roller can be controlled to rotate at a lower rotation speed than in normal operation.

6 Regarding Temperature Control of Heating Roller The temperature of the heating roller is kept constant within a predetermined range, for example, 200 ° C.
In order to maintain the temperature of the heating roller, the heat sensitive element can be brought into thermal contact with the surface of the heating roller. Then, the heat sensitive element is connected to the temperature control circuit. As the heat sensitive element, a thermistor having a negative temperature characteristic or a non-linear resistance element having a positive temperature characteristic can be used.

7 Conveying Sheet When the heating roller is used to heat the object to be heated, the heating roller may be configured to directly contact the object to be heated. It can be configured to intervene. In this case, the transport sheet is allowed to have an endless shape or a roll shape. By using the transport sheet, it becomes possible to smoothly heat and transport the object to be heated.

<Regarding Operation of the Present Invention> When a high frequency voltage is applied to the induction coil, a high frequency magnetic field is generated from the induction coil and interlinks with the secondary coil formed by the first metal coating of the heating roller. That is, the induction coil serves as a primary coil, and air-core transformer coupling is performed between the induction coil and the secondary coil. As a result, the secondary coil forms a closed circuit, so that the secondary current mainly flows in the winding direction of the heating roller. Since the secondary coil has an appropriate secondary side resistance value, Joule heat is generated by the secondary current and the temperature of the heating roller rises. Also, 10
If the transformer coupling is performed at a high frequency of 0 kHz or more, the power transmission efficiency is increased due to the air-core transformer coupling, for example, 95% or more, so that the power is saved. On the other hand, since the roller base and the second metal coating have an inappropriate resistance value in the circumferential direction, substantial air-core transformer coupling is not performed.

Since the second metal film does not allow contact with air even when the first metal film is under high temperature of the heating roller and has an oxidation resistance, the second metal film is not corroded by oxidation. To prevent. As a result, it is possible to obtain a heating roller which has a simple structure but has excellent durability that can be used for a long period of time.

Cu is used as the first metal film and Zn is used as the second metal film.
By forming them by electroplating, the heating roller can be mass-produced on an industrial scale at low cost.

The induction heating roller device according to the second aspect of the invention is
2 by connecting the air core transformer to the induction coil
A heating roller that includes a secondary coil that forms a closed circuit in which the secondary current flows mainly in the orbiting direction and that generates heat, and that has a relatively small heat capacity at both ends in the axial direction;
And an induction coil wound around the axis inside the heating roller.

In order to reduce the heat capacity at both ends of the heating roller, for example, when the roller base body made of the same material is used in the axial direction, the wall thickness may be made thin at both ends. In this case, only both end portions may be thinner than the remaining portion, or may be sequentially thinned from the central portion. Further, the roller base bodies at both ends may be changed to a material having a small specific heat.

The heat radiation at both ends of the heating roller is larger than that at the central portion. Further, since the induction coil is generally arranged with the central portion of the heating roller as the center, the magnetic flux distribution due to the induction coil tends to be smaller than that of the central portion at both ends. Therefore, the amount of heat generated at both ends of the heating roller tends to be smaller than that at the center. As a result, generally, the temperature distribution in the axial direction of the heating roller tends to be low at both ends.

In the present invention, since the heat capacity of the heating roller is set as described above, the temperature of both ends easily rises, so that the temperature distribution of both ends approaches that of the central part, and as a result, the heating roller The uniformity of the temperature distribution along the axial direction is improved.

By implementing the present invention in combination with the invention of claim 1, a further excellent induction heating roller device can be obtained.

The induction heating roller device according to the invention of claim 3 is
2 by connecting the air core transformer to the induction coil
A heating roller provided with a secondary coil that forms a closed circuit in which a secondary current flows mainly in the circumferential direction to generate heat; and an amount of heat generation per unit length along the axial direction of both ends of the heating roller inside the heating roller. Is dispersed along the axial direction so as to be larger than the heat generation amount per unit length along the axial direction of the intermediate portion, and is configured by being wound around the axis,
And a plurality of induction coils each having substantially the same inductance.

The present invention defines a configuration in which the induction coil is improved to improve the uniformity of the temperature distribution along the axial direction of the heating roller. That is, it is possible to control the heat generation amount of the heating roller by changing the pitch of the windings or changing the coil diameter with the same number of turns of the plurality of induction coils.

When the winding pitch of the induction coil is changed, the high frequency power supplied to the heating roller by the induction coil hardly changes, but the coil length of the induction coil changes according to the winding pitch. . As a result, the area of the heating roller facing the induction coil changes, so the amount of heat received per unit length in the axial direction of the heating roller changes. Therefore, the induction coil facing the center of the heating roller makes the pitch of the winding relatively coarse,
If the winding pitch of the induction coil facing the end portion is made relatively dense, the heat generation amount per unit length in the axial direction of the heating roller changes, and the temperature distribution of the heating roller becomes uniform. The pitch of the winding of the induction coil may be constant for each induction coil, or may be continuously or stepwise changed.

When changing the coil diameter of the induction coil,
The distance between the induction coil and the heating roller changes, and the coupling coefficient between the two changes accordingly. When the coupling coefficient increases, the electric power applied to the heating roller and thus the amount of heat generated increase. As a result, the heat generation amount per unit length in the axial direction of the heating roller changes. The coil diameter of the induction coil may be constant for each induction coil, or may be continuously or stepwise changed. In addition, when changing the coil diameter, by changing the diameter of the winding frame according to the coil, the induction coil is not stressed and undesirably deformed, and the creepage insulation distance is increased. You can

No matter which of the winding pitches and coil diameters of the plurality of induction coils is changed, at least by changing the winding pitches or coil diameters of the induction coils at both ends, the remaining induction coil on the center side is changed. Even if they have the same specifications, the effect of the present invention can be obtained.

Since the plurality of induction coils have substantially the same inductance, they can be connected in parallel to a common high frequency power source. Therefore, the output voltage of the high frequency power supply can be lowered. Therefore, the cost of the induction heating roller device including the high frequency power source can be reduced.

When disposing a plurality of induction coils in a distributed manner in the axial direction of the heating roller, it is easy to secure a circular distance by setting an appropriate separation distance between adjacent induction coils. However, if there is no problem of insulation, it is possible to make the temperature distribution along the axial direction of the heating roller uniform by arranging the adjacent induction coils so that some windings overlap each other. it can.

In implementing the present invention, by combining one or both of the first and second aspects of the invention, a more excellent induction heating roller device can be obtained.

The induction heating roller device of the invention of claim 4 is
2 by connecting the air core transformer to the induction coil
A heating roller having a secondary coil that forms a closed circuit in which the secondary current flows mainly in the circumferential direction to generate heat; and the heating roller is dispersed in the axial direction inside the heating roller and is wound around the axis. At least two induction coils; and a temperature sensor arranged so as to detect the temperature of the heating roller in a portion facing each other between a pair of adjacent induction coils.

The present invention defines the arrangement of the temperature sensor in which the influence of the magnetic flux generated from the induction coil on the temperature sensor is reduced. That is, when the temperature sensor crosses the magnetic flux generated by the induction coil, an induced voltage is induced in the temperature sensor, which causes a measurement error. On the other hand, in the present invention, since the magnetic fluxes of the pair of induction coils adjacent to each other intersect in opposite directions at the position where the temperature sensor is arranged, the influence of the magnetic flux hardly occurs due to the cancellation. Therefore, the error of the temperature sensor due to the magnetic flux generated by the induction coil is substantially eliminated.

The temperature sensor may be disposed on either the outer surface side or the inner surface side of the heating roller. In the former case, although the heating roller has some shielding effect on the magnetic flux from the induction coil disposed inside, it is effective because some leakage magnetic flux is generated.

In implementing the present invention, by combining any one or more of the inventions of claims 1 to 3, a more excellent induction heating roller device can be obtained.

The induction heating roller device according to the fifth aspect of the invention is
2 by connecting the air core transformer to the induction coil
A heating roller provided with a secondary coil that forms a closed circuit in which a secondary current mainly flows in the circumferential direction to generate heat; an induction coil wound around an axis inside the heating roller; and an induction coil. It is characterized in that it is provided with a cylindrical winding frame that supports it; and a cooling means that cools the inside of the cylindrical winding frame.

The present invention defines a configuration in which the induction coil is cooled to reduce the temperature rise.

Since the conventional induction coil is disposed inside the heating roller which becomes high temperature, it may be deformed due to high temperature and may be damaged.

In the present invention, since the heating roller and the induction coil are air-core transformer coupled to heat the heating roller, the winding frame of the induction coil can be formed in a tubular shape. Therefore, the hollow portion inside the reel is used for cooling. That is, the cooling means only has to cool the inside of the cylindrical winding frame, and its specific configuration is not limited. For example, use a fan to suck out the air inside the tubular reel,
A structure in which air is pushed into the inside of the cylindrical winding frame from the outside, a spiral fin centering on the shaft is formed on the inner surface of the heating roller,
With the rotation of the heating roller, the internal air is discharged to the outside via the inside of the tubular winding frame, or the air is sent from the outside to the inside of the heating roller and then sent out from the inside of the tubular winding frame to the outside. Can be adopted. Further, the fan may be arranged outside the base end side of the tubular winding frame, or the fan can be integrally formed by cutting and raising the end plate on the drive side of the heating roller. Further, the heat absorbing end of the heat pipe may be inserted inside the tubular winding frame, and the heat exhausting end may be disposed at the heat radiating position.

In implementing the present invention, by combining any one or more of the inventions of claims 1 to 4, a more excellent induction heating roller device can be obtained.

According to the induction heating roller device of the invention of claim 6,
2 by connecting the air core transformer to the induction coil
A heating roller that has a secondary coil that forms a closed circuit in which the secondary current flows mainly in the circulating direction to generate heat, and that is rotatably supported at one end and open at the other end; An induction coil that is arranged in a rotating manner; a winding frame that supports the induction coil, is inserted inside from the other end of the heating roller, and has its base end exposed and supported from the other end of the heating roller to the outside; And bearing means for rotatably coupling the heating roller relative to each other.

The present invention defines the structure of the induction heating roller device which can be easily attached to and detached from the equipment.

A conventional induction heating device is disclosed in, for example, Japanese Patent Laid-Open No. 20
As described in JP-A-00-665453, in order to rotatably support the heating roller, both ends thereof are supported by bearings. Further, the induction coil is disposed inside the heating roller, but since high frequency power is input from an external high frequency power source, the induction coil is placed in a stationary state separately from the heating roller to support both ends in order to facilitate power supply. Is common. Therefore, both ends of the winding frame of the induction coil are exposed and supported outside the heating roller. Therefore, since the heating roller and the induction coil are separately attached and detached, the work is troublesome and the assembly property of the induction heating roller device is poor.

In the present invention, the heating roller and the induction coil are integrated so that one side supports one end of the heating roller and the other side supports the base end of the winding frame of the induction coil, thereby forming an induction heating roller device. Since it is supported at both ends, the support is stable and it is easy to attach and detach.

One end of the heating roller is rotatably supported. A bearing, a drive shaft, or the like can be used as the supporting means. Further, the support of the induction coil may be either stationary or rotatable. In order to support the induction coil, the base end of the winding frame of the induction coil is exposed to the outside from the heating roller and the exposed portion is supported. If the exposed portion is fixedly supported, the induction coil will be in a stationary state. Also, if the exposed part is rotatably supported by a rotary bearing,
The induction coil becomes rotatable.

The bearing means for relatively rotatably coupling the reel and the heating roller couples the reel and the heating roller in a concentric relationship. Therefore, although the number of the bearing means is not limited, it is effective to dispose a pair of bearing means at least at both ends of the winding frame.

Thus, in the present invention, in order to attach the induction heating roller device to the equipment, it suffices to attach the induction heating roller device to the equipment at two locations, one end of the heating roller and the base end of the winding frame. Therefore, the induction heating roller device can be unitized,
It becomes very easy to attach and detach the device.

In implementing the present invention, by combining any one or more of the inventions of claims 1 to 5, a more excellent induction heating roller device can be obtained.

According to the induction heating roller device of the seventh aspect of the invention,
2 by connecting the air core transformer to the induction coil
A heating roller provided with a secondary coil that forms a closed circuit in which a secondary current mainly flows in the circumferential direction to generate heat; an induction coil wound around an axis inside the heating roller; a low-frequency alternating current Rectifying circuit for rectifying power supply voltage, smoothing circuit for smoothing rectified voltage, circuit switching means for selecting rectified voltage and smoothed voltage, and selectively inputting rectified voltage and smoothed voltage for conversion to high frequency voltage And a high frequency power source having a frequency conversion circuit for energizing the induction coil.

The present invention defines the structure of the guide roller device provided with the high frequency power source capable of adjusting the high frequency output. That is, generally, in an image forming apparatus such as a copying machine, in order to heat the fixing roller to the target temperature as soon as possible at the time of startup, the power supplied to the apparatus is increased at startup. Then, once the fixing roller reaches a predetermined temperature, a smaller amount of electric power is supplied after that to prevent the fixing roller from cooling.

Therefore, in the conventional example, for example, a plurality of power supplies are operated in parallel so as to obtain a high output required for high speed heating. However, according to this configuration, since a plurality of power supplies are required, the cost for obtaining a high output becomes high.

In another conventional example, a single power source is used to supply a high output. However, according to this configuration, the DC-
It is necessary to provide a DC power converter to change the DC output. Therefore, the DC-AC power conversion unit and the DC-DC power conversion unit are required to be power conversion units, resulting in an increase in cost.

On the other hand, in the present invention, the high frequency output of the high frequency conversion circuit can be switched in two stages only by switching the input voltage of the frequency conversion circuit between the smoothed voltage and the rectified voltage. That is, the smoothed voltage is a DC voltage that is substantially equal to the peak voltage of the low frequency AC power supply voltage.
On the other hand, the rectified voltage is the average value of the low-frequency AC power supply voltage. Since the rectified voltage is an unsmoothed voltage, its instantaneous value fluctuates, but since it is a power source for heating the heating roller, the load has thermal inertia, so there is no practical problem.

In order to obtain the smoothed voltage and the rectified voltage by switching, the smoothing circuit may be operated or it may be inactively switched. Therefore, it suffices to insert a switch into the smoothing circuit and open / close it.

Further, in the present invention, the high frequency output voltage can be adjusted not only in the above two stages but also in a plurality of stages if necessary. For example, by further operating the high-frequency conversion circuit in a time-division manner to increase or decrease the OFF period of the high-frequency output, it is possible to control the high-frequency output over a wide range in multiple stages stepwise or continuously. Also in the time-division control of high frequency output, if the time interval is appropriately set, there is no problem in heating the load. Further, since the high frequency power source heats the load having thermal inertia as described above, there is no practical problem. Thus, in the present invention, since the circuit configuration is simple, it is possible to obtain an inexpensive induction heating roller device having a high frequency power supply.

The induction heating roller device according to the invention of claim 8 is
2 by connecting the air core transformer to the induction coil
A heating roller having a secondary coil that forms a closed circuit in which a secondary current mainly flows in the circumferential direction to generate heat; and a plurality of heating rollers that are axially dispersed inside the heating roller and are wound around the axis. Induction coil; sheet width detection means for detecting the axial width of the heating roller in the sheet that receives heat while moving while contacting the rotating heating roller; And a high-frequency power source that can be individually adjusted according to the detection signal of the means.

When a sheet body such as an image transfer paper is thermally contacted with the heating roller and fixed, the temperature of the heating roller at the portion where the sheet body contacts and receives heat is lowered, but the sheet body is not contacted. The temperature of the part is in a high state because it does not easily decrease. As a result, the temperature distribution in the axial direction of the heating roller becomes non-uniform. As a result, defects such as defective fixing are likely to occur.

When the sheet body does not come into contact with the heating roller in the axial direction in a part of the heat receiving relationship, the heating temperature of the heating roller in the axial direction is kept uniform by reducing the induction heating of the non-contacting portion. You can

Therefore, in the present invention, the sheet body width detecting means is provided to detect the width of the sheet body in the axial direction of the heating roller. Further, the high frequency power source is configured so that the plurality of induction coils can be individually adjusted according to the detection output of the sheet body width detecting means, thereby controlling the heating of the portion that does not contact the sheet body. As a result, the temperature distribution in the axial direction of the heating roller has an improved degree of uniformity.

The temperature sensor can be provided in each of the portions facing the plurality of induction coils so that the temperature sensor in the portion not in contact with the sheet body can have no effect on the control circuit. The switching at this time can be performed using the detection output of the sheet body width detecting means. Thus, the temperature sensor at the site where the temperature is reduced by the sheet member is made to act, and the high frequency electric power supplied from the induction coil corresponding thereto is controlled, so that the necessary portion of the induction coil can be made to act effectively.

Further, it is possible to construct a resonance circuit that operates for each induction coil by connecting a capacitor to each of the plurality of induction coils in parallel. The capacitor is connected to each induction coil, and together with the induction coil forms a resonance circuit in which the resonance points are not uniform. In addition, "the resonance points are not uniform" means that the resonance points of the plurality of resonance circuits formed by the plurality of pairs of the induction coil and the capacitor are not all the same. For example, 2
When using one induction coil, the resonance points of the respective resonance circuits are set to be different from each other. When three induction coils are used, one resonance circuit formed by at least one induction coil and a capacitor paired therewith and the remaining two resonance circuits are set to have different resonance points. I shall. It is permissible that some of the plurality of resonance circuits have the same resonance point.

A plurality of induction coils of the heating roller are paired with a plurality of capacitors to form a plurality of resonance circuits, and the following operations are performed based on the configuration in which the resonance points are nonuniform. That is, the high frequency power supplied from the induction coil changes according to the magnitude of the terminal voltage of the induction coil. On the other hand, when paying attention to the resonance circuit formed by the induction coil and the capacitor which forms a pair with the induction coil, the voltage applied to the induction coil changes depending on where in the resonance characteristic curve of the resonance circuit the circuit operates. For example, the voltage across the induction coil changes according to the degree of resonance, and the terminal voltage of the induction coil increases as the resonance point approaches. On the other hand, the resonance characteristic becomes steeper as the Q of the resonance circuit increases. Therefore, when the resonance points of the resonance circuits formed by the plurality of induction coils together with the capacitors are different, and when a high-frequency voltage of a certain frequency is commonly applied to the resonance circuits, the resonance circuits have resonance characteristic curves. The applied power to the induction coil whose operating position is closer to the resonance point is larger than that applied to the farther position. In short, if the resonance points are different, the electric power supplied to each induction coil will be different. Also, when the frequency of high frequency is changed, the operating position on the resonance characteristic curve changes,
The applied power changes differently for each induction coil. Further, the plurality of induction coils are dispersed in the axial direction of the heating roller as described above. For this reason, the distribution of the amount of heat generated in the axial direction of the heating roller due to the transformer coupling becomes uneven.

Therefore, by changing the operating frequency by using a single high frequency power source, it is possible to preferentially heat only the region where the temperature rise of the heating roller matches the paper size. However, if the frequencies are selected so that the terminal voltages of the induction coils are equal, the induction coils can be heated to have substantially equal temperatures. For this reason, it is possible to heat to fit a large paper size.

If the operating frequency is controlled by the detection output of the sheet body width detecting means, the above control can be automatically performed. The sheet body width detecting means may use not only the actual width of the sheet body but also the sheet body width selection signal.

Thus, in the present invention, it is possible to save energy and improve the fixability.

By controlling the induction heating region by changing the operating frequency, the high frequency power source can be made inexpensive and the reliability can be improved.

According to a ninth aspect of the present invention, in a fixing device, a fixing device main body having a pressure roller is provided; a heating roller is provided in pressure contact with the pressure roller of the fixing device main body, and a toner image is formed between the two rollers. The induction heating roller device according to any one of claims 1 to 8, wherein the induction heating roller device is arranged so as to fix the toner image while being conveyed while sandwiching the formed recording medium.

In the present invention, the "main body of the fixing device" means
The rest of the fixing device excluding the induction heating roller device.

The pressure roller and the heating roller may be directly in pressure contact with each other, but may be indirectly in contact with each other via a conveying sheet if necessary. The transport sheet may be endless or roll-shaped.

Thus, in the present invention, the toner image can be fixed at a high speed while the recording medium having the toner image formed thereon is conveyed while being sandwiched between the heating roller and the pressure roller.

An image forming apparatus according to a tenth aspect of the present invention includes an image forming apparatus main body provided with an image forming unit for forming a toner image on a recording medium; and a toner image on the recording medium fixed to the image forming apparatus main body. A fixing device according to claim 9;
It is characterized by having.

In the present invention, the "image forming apparatus main body" means the remaining portion of the image forming apparatus excluding the fixing device. The image forming unit is a unit that forms an image on a recording medium to form image information by an indirect method or a direct method. The "indirect method" means a method of forming an image by transfer.

The image forming apparatus corresponds to, for example, an electrophotographic copying machine, a printer, a facsimile or the like.

As the recording medium, for example, a transfer material sheet, a printing paper, an electrofax sheet, an electrostatic recording sheet or the like is applicable.

Thus, in the present invention, an image forming apparatus suitable for high speed type can be obtained.

[0098]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit block diagram showing an overall outline of the first embodiment of the induction heating roller device of the present invention.

FIG. 2 is a partially cutaway central sectional front view of the induction coil and the heating roller.

FIG. 3 is a transverse sectional view of the heating roller.

FIG. 4 is a circuit diagram mainly showing a power supply circuit.

FIG. 5 is a system diagram showing a sheet width control system of the same.

In each drawing, the induction heating roller device includes a heating roller HR, three induction coils IC1, IC2, IC.
3, three capacitors C1, C2, C3, operating circuit O
C, and the sheet body width detecting means SW. Three induction coils IC1, IC2, IC
The three and the three capacitors C1, C2, C form three resonance circuits RC1, RC2, RC3 and are energized by a high frequency power supply HFS described later.

The configuration of each of the above components will be described in detail below.

<Heating Roller HR> Heating Roller H
The R is configured to include the roller base 1, the first metal coating ws, the second metal coating ns, and the protective layer 2, and is rotationally driven by the rotating mechanism RM.

The roller base body 1 is made of a Fe-cast cylinder, and has a length of 300 mm and a thickness of 3 mm, for example.

The first metal film ws is a cylindrical film-shaped film made of a Cu film formed by electroplating.
It consists of a turn coil, and on the outer surface of the roller base 1,
It is arranged over almost the entire effective length in the axial direction.
The thickness of the first metal coating ws is equal to the heating roller HR.
The secondary side resistance value in the orbiting direction is set to 1Ω, which is almost the same value as the secondary reactance.

The second metal film ns is a Zn film formed by electroplating and covers the entire surface of the first metal film ws. The secondary side resistance values of the roller base body 1 and the second metal coating ns are set so as to be values greatly deviated from the secondary reactance.

The protective layer 2 is made of fluororesin and is formed by covering the outer surface of the second metal film ns.

The rotating mechanism RM is a mechanism for rotating the heating roller HR, and is constructed as follows. That is, as shown in FIG. 2, the first end member 3
A, a second end member 3B, a pair of bearings 4, 4, a bevel gear 5, a spline gear 6, and a motor 7 are provided.

The first end member 3A includes a cap portion 3a,
It consists of a drive shaft 3b and a tip 3c. Cap part 3a
2 is fitted to the left end of the heating roller HR in FIG. 2 from the outside, and is fixed to the heating roller HR by using a push screw (not shown).
Supports the left edge of. The drive shaft 3b is the cap portion 3a.
Projects outward from the center of the outer surface of the. Point 3c
From the center of the inner surface of the cap portion 3a to the cap portion 3a
Protruding inward.

The second end member 3B comprises a ring portion 3d. The ring portion 3d supports the right end of the heating roller HR by fitting the right end of the heating roller HR in FIG. 2 from the outside and fixing it to the heating roller HR using a push screw (not shown). There is.

One of the pair of bearings 4 and 4 rotatably supports the outer surface of the cap portion 3a of the first end member 3A. The other rotatably supports the outer surface of the second end member 3B. Therefore, the heating roller HR has the first and second end members 3A and 3B fixed to both ends thereof.
And a pair of bearings 4 and 4 are rotatably supported.

The bevel gear 5 is mounted on the drive shaft 3b of the first end plate 3A. The spline gear 6 meshes with the bevel gear 5. The rotor shaft of the motor 7 is directly connected to the spline gear 5.

<Three induction coils IC1, IC2, IC
About 3> Three induction coils IC1, IC2, IC3
Is the secondary coil w of the heating roller HR, as shown in FIG.
is magnetically coupled to s. Then, as shown in FIG. 2, it is wound around the winding frame 8 and arranged in a distributed manner in the axial direction of the heating roller HR, and is wound in the circumferential direction of the heating roller. In addition, a pair of power supply lead wires 9 are connected in parallel via impedances Z, respectively.

The winding frame 8 is made of a fluororesin cylinder and has a recess 8a, a support 8b and a wire groove 8c. The recess 8a is formed at the center of the tip of the coil bobbin 8 and is rotatably engaged with the rotating mechanism RM. The support portion 8b is formed at the base end of the winding frame 8 and is fixed to a fixing portion (not shown). The wire groove 8c is formed in a part of the outer surface of the winding frame 8 in a gutter shape along the axial direction, and accommodates the power supply lead wire 9 therein. The power supply lead wire 9
3, is housed in the wire groove 1c, led out to the outside from the base end side of the winding frame 8, and connected to the output end of the high frequency power supply HFS via a coaxial cable.

Then, the three induction coils IC1 and IC
2, IC3 are used in a stationary state, the power supply lead wire 9 is housed in the wire passage groove 1c, and the induction coils IC1, IC2,
Since it is close to the IC 3, there is almost no linkage of magnetic flux, so that almost no eddy current loss occurs in the power supply lead wire 9.
On the other hand, the three induction coils IC1, IC2, IC3 are inserted into the heating roller HR from the ring portion 3d of the second end member 3B, and the recess 1a formed at the tip of the winding frame 8 is the first. The support portion 1b formed at the base end as described above is engaged with the sharp end portion 3c of the end plate 3A and is fixed to the fixing portion, so that the support portion 1b is supported coaxially with the heating roller HR and is heated. Even if the roller HR rotates, it remains stationary.

<Regarding Three Capacitors C1, C2, C3> As shown in FIGS. 1 and 4, the three capacitors C1, C2, C3 have three induction coils IC1, IC.
2, 3 connected in parallel to IC3, three resonance circuits RC1, R
C2 and RC3 are formed. In FIG. 4, R
_ws represents the equivalent resistance of the closed circuit formed by the secondary coil _ws of the heating roller HR.

<Regarding Three Resonant Circuits RC1, RC2, and RC> Of the three resonant circuits RC1, RC2, and RC3, RC1 and RC2 have their resonance points indicated by curve A in FIG. 5, and RC3 indicates curve B. Is. That is, the resonance points of the curves A and B are deviated from each other.

<Regarding the operating circuit OC> The operating circuit OC
Is a DC power source DC as shown in FIGS. 1, 4 and 5.
And a high frequency power supply HFS.

(Regarding High-Frequency Power Supply HFS) The high-frequency power supply HFS supplies high-frequency power to each induction coil IC1, IC2, IC3, and its input end is connected to the output end of the DC power supply DC. The input end of the DC power supply DC is connected to the low frequency AC power supply AS.

As shown in FIG. 4, the high frequency power supply HFS includes a high frequency filter HFF, a variable frequency high frequency oscillator OSC, a gate drive circuit GDC, a half bridge type inverter main circuit HBI, a load circuit LC and an external signal source OSS. It is composed by.

The high frequency filter HFF is composed of a DC power source DC and a half bridge type inverter main circuit HBI which will be described later.
Is interposed between the two to prevent the high frequency from flowing out to the low frequency AC power supply AS side.

The high frequency oscillator OSC is of variable oscillation frequency, generates a high frequency signal of a predetermined frequency, and inputs it to the drive circuit DC.

The gate drive circuit GDC is composed of a preamplifier, amplifies the high frequency signal sent from the high frequency oscillator OSC and outputs a drive signal.

Half Bridge Inverter Main Circuit HBI
Are connected in series between DC power source DC output terminals, which will be described later, and are excited by a drive signal of the drive circuit DC to switch alternately, and a pair of MOSFETs Q1 and Q2 and a pair of MOSFET Q.
1, Q2, and capacitors C4 and C5 connected in parallel, and converts the DC output of the DC power supply DC into a high frequency wave having a substantially rectangular wave. The capacitors C4 and C5 perform a high frequency bypass action during the operation of the inverter.

The load circuit LC is a DC cut capacitor C
6, inductor L1, three capacitors C1, C2, C
It is composed of three. DC cut capacitor C6
Prevents the direct current component from flowing into the load circuit LC from the direct current power supply DC side via the pair of MOSFETs Q1 and Q2. Inductor L1 and three capacitors C1, C2, C3
Form a series resonance circuit to form three induction coil ICs.
The high frequency voltage applied to both ends of IC1, IC2 and IC3 is shaped into a sine wave. The three induction coils IC1, IC2, and IC3 are energized by the waveform-shaped high-frequency voltage.

The external signal source OSS is the sheet width detecting means W.
It is controlled by D to change the output frequency of the high frequency power supply HFS, and functions to control the oscillator OSC and change its oscillation frequency.

(About DC power supply DC) DC power supply DC
Is a rectifier circuit, the input end of which is connected to the low-frequency AC power supply AS to convert the low-frequency AC voltage into a non-smoothed DC voltage,
Output from the DC output terminal.

(Low Frequency AC Power Supply AS) The low frequency AC power supply AS is, for example, a 100V commercial AC power supply.

<Regarding Sheet Body Width Detection Means WS> The sheet body width detection means WS is means for detecting the width of the sheet body P that is in thermal contact with the heating roller HR and receives heat, and outputs a detection signal to the external signal source OSS. Send out.

<Regarding the Operation of the Induction Heating Roller Device> The low-frequency AC voltage of the low-frequency AC power supply AS is converted into a DC voltage by the DC power supply DC, and further converted into a high-frequency voltage by the high-frequency power supply HFS. Induction coil IC
1, IC2, IC3.

By the way, the resonance characteristic of the resonance circuit RC1 formed by the induction coil IC1 and the capacitor C1 is preset as shown by the curve A in FIG. On the other hand, the resonance characteristics of the resonance circuits RC2 and RC3 formed by the induction coils IC2 and IC3 and the capacitors C2 and C3 are similarly set in advance as indicated by the curve B in FIG.

Therefore, in FIG. 5, when the sheet body width detecting means WD detects that the width of the sheet body P that receives heat is large (for example, A3), the external signal source O of the operating circuit OC.
SS is controlled. At this time, in FIG. 4, the external signal source OSS controls the oscillator OSC of the high frequency power supply HFS to set the oscillation frequency to f1. Although the two resonance characteristics are different, impedances indicated by absolute values are equal at the frequency f1, so that the high-frequency voltage applied to the induction coils IC1, IC2, and IC3 and therefore the amount of heat generation are substantially equal. As a result, the temperature of the heating roller HR is determined by the curve C in FIG.
As shown in FIG.

FIG. 6 is a graph showing resonance characteristics of three resonance circuits in the first embodiment of the heating roller device of the present invention. In the figure, the horizontal axis represents frequency and the vertical axis represents impedance.

FIG. 7 is a graph showing the temperature distribution in the axial direction of the heating roller when the frequencies are f1 and f2. In the figure, the horizontal axis represents the position (in the axial direction) of the heating roller, and the vertical axis represents the temperature.

On the other hand, when the sheet body width detecting means WS detects that the width of the sheet body P is small (for example, A4), the external signal source OSS of the operating circuit OC is controlled again. Therefore, in FIG. 4, the external signal source OSS controls the oscillator OSC of the high frequency power supply HFS again, but this time changes the oscillation frequency to f2. As a result, the resonance circuits RC2 and RC3 are energized substantially at the resonance point of the resonance characteristic, but the resonance circuit RC1 largely deviates from the resonance point, so that the terminal voltage of the former becomes higher and that of the latter becomes lower. Therefore, the temperature distribution of the heating roller HR is as shown in FIG.
As shown by the curve D in FIG. 5, the height is high over the central portion and the right area of the drawing, and the left area is low.

FIG. 8 is a system diagram showing a second embodiment of the induction heating roller device of the present invention. In the figure, the same parts as those in FIGS. 1 and 5 are designated by the same reference numerals and the description thereof will be omitted.

In this embodiment, the heating roller HR can be controlled to an appropriate temperature according to the sizes of the sheet bodies P1 and P2. Along with this, the induction coil IC
1-IC6, temperature sensors S1-S6, temperature sensor selection circuit SS, sheet body width detection means WD1, WD2, WD3, and high frequency power supply HFS are different.

The induction coils IC1 to IC6 are distributed in the axial direction of the heating roller HR.

The temperature sensors S1 to S6 are connected to the respective induction coils I
It is arranged so as to detect the surface temperature of the heating roller HR facing C1 to IC6.

The temperature sensor selection circuit SS includes a temperature sensor S
1 to S6 can be selectively actuated.

The sheet width detecting means WD1 detects the A2 size sheet P1. Sheet width detection means WD2
Detects a sheet body P2 of A3 size. In the case of A4 size sheet body P3, which sheet body width detecting means W
Since neither D1 nor WD2 is detected, it can be recognized that the sheet body P3 has A4 size.

The high frequency power supply HFS is composed of each induction coil IC1.
The input power to the IC6 can be controlled according to the width of the sheet P1 or P2.

Thus, when the sheet body P1 receives heat, the temperature sensor S1 or S6 acts. At this time, the temperature sensors S2 to S5 may be operated or may not be operated.

Next, when the sheet body P2 receives heat, the temperature sensor S2 or S5 acts. At this time,
The temperature sensors S1 and S6 are made inoperative. The temperature sensors S3 and S4 may be operated or may not be operated.

Further, when the sheet body P3 receives heat,
The temperature sensor S3 or S4 acts. At this time, the temperature sensors S1, S2, S5, S6 are made inoperative.

FIG. 9 is a schematic cross-sectional view of a heating roller in the third embodiment of the induction heating device of the present invention.

In this embodiment, the thickness of the heating roller HR is gradually reduced from the center to both ends. As a result, in general, the temperature at both ends of the heating roller HR tends to decrease as compared with the central part, but since the heat capacity at both ends is small, it is possible to reduce the temperature decrease.

FIG. 10 is a partially sectional front view showing a fourth embodiment of the induction heating device of the present invention. In the figure, the same parts as those in FIG. 2 are designated by the same reference numerals and the description thereof will be omitted.

In this embodiment, the heating roller HR and the induction coil IC are unitized to facilitate attachment / detachment to / from equipment.

That is, the heating roller HR is opened at the other end, and is supported by a device (not shown) at one end by the bearing means B1 via the drive shaft 3b.

The induction coil IC is inserted into the heating roller HR together with the winding frame 8 while being mounted on the winding frame 8. Then, both ends of the insertion portion have bearing means B2, B3.
Is rotatably coupled to the heating roller HR via.

The winding frame 8 has its base end exposed to the outside from the open end of the heating roller HR. In addition, a mounting hole 8d at the base end
Is formed and is configured to be fixed to the device.

In this way, the induction heating roller device can be attached to and detached from the device at two locations, the bearing means B1 and the mounting hole 8d.

FIG. 11 is a partially sectional front view showing a fifth embodiment of the induction heating device of the present invention. In the figure, the same parts as those in FIG. 10 are designated by the same reference numerals and the description thereof will be omitted.

In this embodiment, the induction coil IC is positively cooled through the inside of the winding frame 8.

That is, the winding frame 8 is formed hollow and both ends are open.

The fan F is integrally formed by cutting and raising the end member 3A of the heating roller HR.

The open end on the front end side of the winding frame 8 faces the fan F. The base end is fixed to the device via the fixing member 9, but the open end is opened to the inside of the device.

Since the fan F rotates in accordance with the rotation of the heating roller HR, the air inside the device is sucked into the heating roller HR as shown by the arrow in the figure, and the tip of the reel 8 is further drawn. To the inside, and is discharged into the device from the open end of the base end. Then, the induction coil IC is cooled through the wall surface of the winding frame 8 while air is moving inside the winding frame 8.

Next, sixth to eighth embodiments of the present invention in which the high frequency output is made variable will be described with reference to FIGS. 12 to 15. In the figure, the same parts as those in FIG. 4 are designated by the same reference numerals and the description thereof will be omitted.

FIG. 12 is a circuit diagram showing a sixth embodiment of the induction heating roller device of the present invention.

In this embodiment, the high frequency output of the high frequency power supply HFS can be controlled in two steps. In the figure, a series circuit of a smoothing capacitor C7 and a switch SW is connected between lines between a DC power supply DC composed of a rectifying circuit and an input end of a high frequency power supply HFS.

Then, when the switch SW is turned on, the smoothing capacitor C7 operates, so that the high and low output state of 141 V between the input terminals of the high frequency power supply HFS can be set as the start-up time.

Next, when the switch SW is turned off, the smoothing capacitor C7 becomes inactive, and a non-smoothed DC voltage is applied. The average value of the DC voltage at this time is 100V. Therefore, the high frequency power supply HFS is in a low output state. This low output state can be set to normal operation.

FIG. 13 is a circuit diagram showing a seventh embodiment of the induction heating roller device of the present invention.

This embodiment differs from FIG. 12 in that the inductor L is inserted in series in the line between the DC power supply DC and the series circuit of the smoothing capacitor C7 and the switch SW.

FIG. 14 is a circuit diagram showing an eighth embodiment of the induction heating roller device of the present invention.

FIG. 15 is also a high frequency output waveform diagram.

In addition to the configuration shown in FIG. 13, the present embodiment is constructed so that the high frequency power supply HFS can perform the time division operation by the time division control signal TS. Therefore, the high frequency power supply HFS intermittently generates the high frequency output HF as shown in FIG. 15, so that the high frequency output can be changed in multiple stages. DC power supply DC and smoothing capacitor C
Inductor L between 7 and the series circuit of switch SW
Is inserted in the line in series, which is different from FIG.

Next, with reference to FIGS. 16 to 21, the ninth to thirteenth embodiments will be described in which the uniformity of the temperature of the heating roller is improved.

FIG. 16 is a conceptual diagram showing the arrangement of induction coils in the ninth embodiment of the present invention.

In this embodiment, six induction coils IC1 to
The number of turns and the winding diameter of the IC 6 are the same, and the winding pitch and hence the coil length are changed. That is, the induction coils IC1 and IC6 have the smallest coil length. The induction coils IC3 and IC4 have the largest coil length. The induction coils IC2 and IC5 have intermediate coil lengths. However, since the induction coils IC1 to IC6 have the same number of windings, they have the same inductance. Therefore, it can be connected in parallel to the high frequency power supply. Further, even if the power applied to each of the induction coils IC1 to IC6 is the same, the power per unit length changes in proportion to the coil length.
Therefore, the uniformity of the temperature of the heating roller is improved.

FIG. 17 is a conceptual diagram showing the arrangement of induction coils in the tenth embodiment of the present invention.

In this embodiment, four induction coils IC1.about.
16 in that IC4 is used.

FIG. 18 is a conceptual diagram showing the arrangement of induction coils in the eleventh embodiment of the present invention.

In this embodiment, each induction coil IC1 to IC
The winding diameter is changed by making the number of turns and winding pitch of 6 and therefore the coil length the same. That is, the induction coil I
C1 and IC6 have the largest winding diameter. Induction coil IC
3 and IC4 have the smallest winding diameter. Induction coil IC
2, IC5 has an intermediate winding diameter. However, since the induction coils IC1 to IC6 have the same number of windings, they have the same inductance, but have different coupling coefficients with the secondary coil of the heating roller HR, and the larger the winding diameter, the larger the coupling coefficient. Therefore, each induction coil IC1 to I
The high frequency power supplied from C6 to the secondary coil changes according to the coupling coefficient. Therefore, the uniformity of the temperature of the heating roller is improved.

FIG. 19 is a conceptual diagram showing the arrangement of induction coils in the twelfth embodiment of the present invention.

In this embodiment, each induction coil IC1 to IC
The number of turns and the winding pitch of 6 and thus the coil length are the same, and the winding diameter is changed in the induction coil and between the induction coils. That is, the induction coils IC1 to IC6 are
The winding is large on the end side of the heating roller and small on the center side,
It is changing in the middle. The winding diameter also changes between the adjacent induction coils. Therefore, the high-frequency power supplied from the induction coils IC1 to IC6 to the secondary coil continuously changes in the axial direction of the heating roller. Therefore, the temperature uniformity of the heating roller is further improved.

FIG. 20 is a sectional view showing a thirteenth embodiment of the induction heating roller device of the present invention.

FIG. 21 is a graph which conceptually illustrates the temperature distribution of the heating roller.

In the figure, the same parts as those in FIG. 2 are designated by the same reference numerals and the description thereof will be omitted. In this embodiment,
Adjacent portions of the induction coils IC1 to IC5 are wound and wound. Therefore, the temperature distribution of the heating roller becomes uniform.

FIG. 22 is a sectional view showing a fourteenth embodiment of the induction heating roller device of the present invention.

In the present embodiment, the temperature sensors S1 and S2 are arranged in a portion facing the middle of the induction coils IC1, IC2 and IC3. Therefore, for example, the induction coil IC1
Even if the magnetic flux generated by the IC2 adjacent to the temperature sensor S1 penetrates the temperature sensor S1, the magnetic flux is canceled by the temperature sensor S1, so that the influence of the magnetic flux can be removed.

FIG. 23 is a sectional view showing a fifteenth embodiment of the induction heating roller device of the present invention.

In this embodiment, the temperature sensors S1, S2, S are used.
3 is arranged at a portion directly facing the induction coils IC1, IC2 and IC3. However, the temperature sensors S1, S2, S3
Is disposed via the heating roller HR, the heating roller HR is configured by using a roller base body made of Fe. Therefore, the roller base body performs a shielding action on the magnetic flux, and thus the influence of the magnetic flux is removed. it can.

Further, since the portion where the temperature sensors S1, S2, S3 are arranged is heated at the highest temperature by the induction coils IC1, IC2, IC3, and the temperature change due to the positional deviation is small, the temperature control Accuracy is improved.

FIG. 24 is a longitudinal sectional view showing an embodiment of the fixing device of the present invention.

In the figure, 21 is an induction heating roller device,
22 is a pressure roller, 23 is a recording medium, 24 is toner, 2
5 is a mount, and IC is an induction coil.

The induction heating roller device 21 uses the first embodiment shown in FIGS.

The pressure roller 22 is the induction heating roller device 2
The heating roller HR is arranged in pressure contact with the first heating roller HR, and conveys the recording medium 23 while narrowing the pressure between the two.

An image is formed on the recording medium 23 by attaching the toner 24 to the surface thereof.

The pedestal 25 mounts each of the above components (excluding the recording medium 23) in a predetermined positional relationship.

In the fixing device, the recording medium 23 on which the toner 24 is attached to form an image is inserted between the heating roller HR and the pressure roller 22 of the induction heating roller device 21 and conveyed. At the same time, the toner 24 is heated and melted by the heat of the heating roller HR, and thermal fixing is performed.

FIG. 25 is a conceptual sectional view of a copying machine as an embodiment of the image forming apparatus of the present invention.

In the figure, 31 is a reading device, 32 is an image forming unit, 33 is a fixing device, and 34 is a case of the image forming device.

The reading device 31 optically reads the base paper and forms an image signal.

The image forming means 32 forms an electrostatic latent image on the photosensitive drum 32a based on the image signal, attaches toner to the electrostatic latent image to form a reverse image, and records the image on paper or the like. Transfer to a medium to form an image.

The fixing device 33 has the structure shown in FIG. 24 and heats and fuses the toner adhering to the recording medium to heat-fix it.

The image forming apparatus case 34 accommodates the above-described devices and means 31 to 33, and is provided with a carrying device, a power supply device, a control device, and the like.

[0203]

According to the first aspect of the present invention, the secondary circuit is provided on the surface of the roller base body and is coupled to the later-described induction coil by the air-core transformer so that the secondary current mainly flows in the circumferential direction to generate heat. A heating roller provided with a first metal coating forming a secondary coil and an oxidation-resistant second metal coating covering the surface of the first metal coating, and a heating roller disposed inside the heating roller wound around an axis. By including the installed induction coil, it is possible to provide an induction heating roller device having a simple structure and excellent durability that can be used for a long period of time.

According to the second aspect of the present invention, there is provided a secondary coil forming a closed circuit in which a secondary current mainly flows in the circulating direction to generate heat by air-core transformer coupling to the induction coil described later, and The heating roller has a relatively small heat capacity at both ends in the axial direction, and an induction coil wound around the axis inside the heating roller to provide a temperature distribution of the heating roller. It is possible to provide an induction heating roller device having good uniformity.

According to the third aspect of the present invention, a heating roller provided with a secondary coil which forms a closed circuit in which a secondary current mainly flows in the winding direction to generate heat by air-core transformer coupling to the induction coil described later. And the amount of heat generated per unit length along the axial direction of both ends of the heating roller is greater than the amount of heat generated per unit length along the axial direction of the intermediate portion, and the heat is distributed along the axial direction. By providing a plurality of induction coils that are wound around each other and have substantially the same inductance, it is possible to provide an induction heating device with a good temperature distribution uniformity of the heating roller. .

According to the invention of claim 4, a heating roller provided with a secondary coil forming a closed circuit in which a secondary current mainly flows in the circumferential direction to generate heat by connecting the induction coil to an air-core transformer. And at least two induction coils that are distributed in the axial direction and are wound around the axis, and are arranged so as to sense the temperature of the heating roller in a portion facing between a pair of adjacent induction coils. It is possible to provide the induction heating roller device in which the influence of the temperature sensor due to the magnetic flux of the induction coil is reduced by including the temperature sensor.

According to the invention of claim 5, a heating roller provided with a secondary coil forming a closed circuit in which a secondary current mainly flows in the winding direction to generate heat by coupling the induction coil with an air-core transformer. And an induction coil wound around the axis inside the heating roller, a tubular winding frame that supports the induction coil, and a cooling unit that cools the inside of the tubular winding frame. As a result, it is possible to provide the induction heating roller device in which the induction coil is cooled and its deformation is prevented.

According to the sixth aspect of the present invention, the induction coil is provided with a secondary coil which forms a closed circuit for generating heat by air-core transformer coupling to the after-mentioned secondary current mainly flowing in the winding direction. A heating roller that is rotatably supported at its other end and an induction coil that is wound around an axis inside the heating roller, and that supports the induction coil and is inserted from the other end of the heating roller into the inside. The heating roller is provided with a winding frame whose base end is exposed to the outside from the other end of the heating roller and supported, and bearing means for rotatably coupling the winding frame and the heating roller. It is possible to provide an induction heating device in which the induction coil is unitized to facilitate the attachment / detachment to / from the device.

According to the invention of claim 7, a heating roller provided with a secondary coil which forms a closed circuit in which a secondary current mainly flows in the circumferential direction to generate heat by being coupled to an induction coil by an air-core transformer. An induction coil wound around the axis of the heating roller, a smoothing circuit for smoothing the rectified voltage of the rectifying circuit, a circuit switching means for selecting the rectified voltage and the smoothed voltage, and the rectified voltage and the smoothing. By including the high frequency power supply having the frequency conversion circuit for selectively inputting the voltage, it is possible to provide the induction heating roller device in which the high frequency power for the heating roller is variable.

According to the invention of claim 8, a heating roller provided with a secondary coil which forms a closed circuit in which a secondary current mainly flows in the circumferential direction to generate heat by being coupled to the induction coil by an air-core transformer. And a plurality of induction coils that are distributed in the axial direction of the heating roller and are wound around the axis, and the heating roller in the axial direction of the heating roller in the sheet body that receives heat while moving while contacting the rotating heating roller. Since the width of the sheet body is provided with the sheet body width detecting means for detecting the width and the high frequency power source capable of individually adjusting the input power to the plurality of induction coils according to the detection signal of the sheet body width detecting means. It is possible to provide an induction heating roller device that can easily perform heating according to the above.

According to the invention of claim 9, the fixing device main body having the pressure roller and the induction heating roller device according to any one of claims 1 to 8 are provided.
A fixing device having the effects of claims 1 to 8 can be provided.

According to the invention of claim 10, an image forming apparatus having the effects of claims 1 to 8 is provided by including the image forming apparatus main body and the fixing device of claim 9. You can

[Brief description of drawings]

FIG. 1 is a circuit block diagram showing an overall outline of a first embodiment of an induction heating roller device of the present invention.

FIG. 2 is a partially cutaway central sectional front view of the induction coil and the heating roller.

FIG. 3 is a transverse sectional view of the heating roller.

FIG. 4 is a circuit diagram mainly showing a power supply circuit.

FIG. 5 is a system diagram showing a seat width control system.

FIG. 6 is a graph showing resonance characteristics of three resonance circuits in the first embodiment of the heating roller device of the present invention.

FIG. 7 is a graph showing an axial temperature distribution of the heating roller when the frequencies are f1 and f2.

FIG. 8 is a system diagram showing a second embodiment of the induction heating roller device of the present invention.

FIG. 9 is a schematic cross-sectional view of a heating roller in a third embodiment of the induction heating device of the present invention.

FIG. 10 is a partial cross-sectional front view showing a fourth embodiment of the induction heating device of the present invention.

FIG. 11 is a partial cross-sectional front view showing a fifth embodiment of the induction heating device of the present invention.

FIG. 12 is a circuit diagram showing a sixth embodiment of the induction heating roller device of the present invention.

FIG. 13 is a circuit diagram showing a seventh embodiment of the induction heating roller device of the present invention.

FIG. 14 is a circuit diagram showing an eighth embodiment of the induction heating roller device of the present invention.

FIG. 15 is a high frequency output waveform diagram.

FIG. 16 is a conceptual diagram showing the arrangement of induction coils in a ninth embodiment of the present invention.

FIG. 17 is a conceptual diagram showing the arrangement of induction coils in the tenth embodiment of the present invention.

FIG. 18 is a conceptual diagram showing the arrangement of induction coils in the eleventh embodiment of the present invention.

FIG. 19 is a conceptual diagram showing the arrangement of induction coils in the twelfth embodiment of the present invention.

FIG. 20 is a sectional view showing a thirteenth embodiment of the induction heating roller device of the present invention.

FIG. 21 is a graph conceptually explaining the temperature distribution of the heating roller.

FIG. 22 is a sectional view showing a fourteenth embodiment of the induction heating roller device of the present invention.

FIG. 23 is a sectional view showing a fourteenth embodiment of the induction heating roller device of the present invention.

FIG. 24 is a vertical sectional view showing an embodiment of a fixing device of the present invention.

FIG. 25 is a conceptual cross-sectional view of a copying machine as an embodiment of the image forming apparatus of the present invention.

[Explanation of symbols]

1 ... Roller base 2 ... Protective layer ws ... first metal coating ns ... second metal coating

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H05B 6/36 H05B 6/36 E 6/44 6/44 (72) Inventor Hiroyuki Doi Asahi Imabari, Ehime Prefecture Harison TOSHIBA LIGHTING CO., LTD. (5) 2-5, Machi (72) Inventor Gaku Gaku 1 HARISON TOSHIBA LIGHTING CO., LTD. (2) 5-2, Asahi-cho, Imabari-shi, Ehime (72) Inventor Toshiya Suzuki Imabari, Ehime Harison TOSHIBA LIGHTING CO., LTD., 5-2 Asahi-cho, Yokohama-shi (72) Inventor Takaaki Tanaka 1- HARISON TOSHIBA LIGHTING CO., LTD. 5-2, Asahi-cho, Imabari-shi, Ehime (reference) 2H033 AA03 BA25 BA29 BB03 BB05 BB13 BB14 BB18 BB28 BB37 BE06 CA07 CA09 CA17 CA23 CA28 CA30 CA44 3K059 AA02 AA10 AB04 AB08 AB09 AC33 AD05 CD48 CD52

Claims (10)

[Claims] 1. A roller base and a closed-circuit secondary coil which is disposed on the surface of the roller base and is coupled to an induction coil to be described later by an air-core transformer so that a secondary current mainly flows in the circumferential direction to generate heat. A first metal coating, and a heating roller having an oxidation-resistant second metal coating covering the surface of the first metal coating; and an induction coil wound around an axis inside the heating roller. And an induction heating roller device. 2. A secondary coil which forms a closed circuit in which a secondary current mainly flows in a circulating direction to generate heat by coupling an induction coil to an induction coil, which is described below,
Induction heating, characterized by comprising: a heating roller having a relatively small heat capacity at both ends in the axial direction; and an induction coil wound around the axis inside the heating roller. Roller device. 3. A heating roller provided with a secondary coil forming a closed circuit in which a secondary current mainly flows in a circumferential direction to generate heat by connecting an induction coil to an air-core transformer; Dispersion along the axial direction so that the heat generation amount per unit length along the axial direction of both ends of the heating roller is larger than the heat generation amount per unit length along the axial direction of the middle part, An induction heating roller device comprising: a plurality of induction coils that are wound and have substantially the same inductance. 4. A heating roller provided with a secondary coil which forms a closed circuit in which a secondary current mainly flows in a circumferential direction to generate heat by coupling an induction coil to an air-core transformer, which is described later; At least two induction coils distributed in the axial direction and wound around the axis; arranged so as to sense the temperature of the heating roller in a portion facing each other between a pair of adjacent induction coils An induction heating roller device comprising: a temperature sensor; 5. A heating roller provided with a secondary coil which forms a closed circuit in which a secondary current mainly flows in a circulating direction to generate heat by coupling an induction coil to an induction coil described below; An induction coil wound around an axis and arranged; a tubular winding frame supporting the induction coil;
An induction heating roller device, comprising: a cooling means for cooling the inside of the cylindrical winding frame; 6. A secondary coil is provided which forms a closed circuit in which a secondary current mainly flows in a circulating direction to generate heat by being coupled to an induction coil by an air-core transformer.
A heating roller that is rotatably supported at one end and the other end is open; an induction coil that is wound around an axis inside the heating roller; and supports the induction coil and from the other end of the heating roller to the inside. A winding frame which is inserted and has its base end exposed to the outside from the other end of the heating roller and supported; and a bearing means for relatively rotatably coupling the winding frame and the heating roller. Induction heating roller device. 7. A heating roller provided with a secondary coil which forms a closed circuit in which a secondary current mainly flows in a circulating direction to generate heat by coupling an induction coil to an air-core transformer, which is described later; An induction coil wound around an axis; a rectifying circuit for rectifying a low-frequency AC power supply voltage, a smoothing circuit for smoothing the rectified voltage, a circuit switching means for selecting the rectified voltage and the smoothed voltage, and a rectified voltage And a high-frequency power source having a frequency conversion circuit for selectively inputting the smoothed voltage and converting the smoothed voltage into a high-frequency voltage to energize the induction coil; 8. A heating roller provided with a secondary coil which forms a closed circuit in which a secondary current mainly flows in a circulating direction to generate heat by coupling an induction coil to an induction coil described below; A plurality of induction coils distributed in the axial direction and wound around the axis;
A sheet body width detecting means for detecting the axial width of the heating roller in the sheet body which receives heat while moving while contacting the rotating heating roller; and input power to a plurality of induction coils as a detection signal of the sheet body width detecting means. An induction heating roller device, comprising: a high frequency power source that can be adjusted individually according to the requirements. 9. A fixing device main body having a pressure roller; a heating roller is provided in pressure contact with the pressure roller of the fixing device main body, and a recording medium having a toner image formed thereon is sandwiched between the both rollers. A fixing device comprising: the induction heating roller device according to any one of claims 1 to 8, which is arranged to fix a toner image while being conveyed. 10. An image forming apparatus main body provided with an image forming unit for forming a toner image on a recording medium; and a toner image on the recording medium fixed to the image forming apparatus main body.
An image forming apparatus comprising: the fixing device described above;