JP2005093352A - Induction heating roller device, fixing device, and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an induction heating roller device, in which a plurality of heated regions can be installed selectively in a shaft direction of the heating roller and heating characteristics in the desired heated region of the heating roller are made, and to provide a fixing device and an image-forming device provided with the induction heating roller device. <P>SOLUTION: This induction heating roller device includes the heating roller HR which can be switched to a plurality of heated regions according to the size of the heated material and a plurality of the induction coils IC 1, IC 2 which are installed opposite to each other in the respective heated regions, and the respective induction coils are provided with a plurality of unit induction coils IC<SB>U</SB>1, IC<SB>U</SB>2 which are connected in parallel; and the device is provided with the induction coil device IC in which the numbers of the coil turns of the unit induction coils are different corresponding to the heated regions, a high-frequency power source HFS to supply the high-frequency electric power to the induction coil device IC, and an induction coil selecting means PAM that controls high-frequency power to be supplied to the respective induction coils of the induction coil device and switches the heated regions of the heating roller. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an induction heating roller device, a fixing device including the induction heating roller device, and an image forming apparatus.

  Conventionally, a heating roller using a halogen light bulb as a heat source has been used for heat-fixing a toner image, but there is a problem that efficiency is poor and a large amount of power is required. Therefore, development has been carried out to solve this problem by introducing an induction heating method. As an induction heating method for this kind of purpose, an eddy current loss method (for example, see Patent Document 1) and a transformer method (for example, see Patent Document 2) are known.

  The eddy current loss method has the same operation principle as that in practical use in IH jars. In addition, the frequency of the high frequency used in the eddy current loss method is about 20 to 100 kHz. On the other hand, the transformer system has higher steady-state efficiency due to stronger magnetic coupling than the eddy current loss method, and the entire heating roller can be heated, so the structure of the fixing device is simpler than the eddy current loss method. There is an advantage of becoming. In addition, by increasing the operating frequency to 100 kHz or higher, preferably 1 MHz or higher, it is possible to increase the Q of the induction coil and increase the power transmission efficiency. For this reason, the overall efficiency of heating is increased and power saving can be achieved. In addition, there is an advantage that the structure of the fixing device is simplified as compared with the eddy current loss method. Furthermore, the heat capacity can be made considerably smaller than that of the eddy current loss type heating roller. Therefore, the transformer method is suitable for speeding up heat fixing.

  Furthermore, as an improved version of the transformer system, by forming the secondary side resistance value of the heating roller having a hollow structure rotatably supported by the air core transformer coupled to the induction coil in a closed circuit substantially equal to the secondary reactance, The present applicant has applied for a patent for an air-core transformer coupling method in which the power transmission efficiency from the induction coil to the heating roller is increased and a remarkable effect of efficiently heating the heating roller can be obtained (see Patent Document 3). According to the present invention, it is possible to save power in induction heating of the heating roller and to easily increase the speed of thermal fixing.

  Furthermore, in order to be able to heat only a desired heating area of the induction roller according to the size of the fixing paper on which the toner image is formed, a plurality of pieces divided into a plurality along the axial direction of the induction heating roller A technique for arranging an induction coil and selectively allowing high-frequency power to be applied to an induction coil corresponding to a specific region has been developed by the present inventors, for example, as Japanese Patent Application No. 2002-120365. Patent application has been filed.

In the configuration in which the heating region of the heating roller can be switched by arranging the plurality of induction coils as described above, in order to make the temperature distribution in the axial direction of the heating roller uniform, adjacent to the coil turn interval in each induction coil. The distance between the pair of induction coils is equal to each other.
JP 2000-215974 A JP 59-33787 JP 2002-222688

  When setting a plurality of heating regions to be selectable on the heating roller, prepare a unit induction coil having a predetermined number of coil turns, coil diameter and axial length, and the required unit induction coil according to the axial length of the heating region By connecting the number in parallel to the high-frequency power source via the induction coil selection means, the heating value per unit axis length can be made constant for any heating region.

  However, even if the calorific value per unit axis length is constant, the heat consumption pattern differs depending on various circumstances such as the heat transfer mode of the heating roller and the mode of use for heating the heated object. The roller temperature is not always constant. For example, when the heating roller is supported at both ends thereof, bearing mechanisms are provided at both ends, so that the heat of the heating roller easily escapes to the bearing mechanisms at both ends, so that the temperature at both ends of the heating roller is reduced. It tends to decline. In addition, when a plurality of heating areas are set on the heating roller, it is generally designed so that the ratio of using the heating area located at the center of the heating roller is the largest. Therefore, in such a case, the heat consumption in the central portion of the heating roller is the largest, so it is preferable to design so that the temperature rising efficiency in this portion is excellent.

  On the other hand, when a fixing device that heats an object to be heated formed of a recording medium on which a toner image is formed by incorporating an induction heating roller device, it is desired that the heating efficiency is high and the fixing performance is good.

  The present invention can selectively set a plurality of heating regions in the axial direction of the heating roller, and has an induction heating roller device that has good heating characteristics in a desired heating region of the heating roller, and a fixing device including the same. An object is to provide an image forming apparatus.

  Another object of the present invention is to provide a fixing device having high heating efficiency and good fixing performance, and an image forming apparatus including the same.

    An induction heating roller device according to a first aspect of the present invention is a heating roller that is magnetically coupled to an induction coil device, which will be described later, and generates heat by an induced current, and is switched to a plurality of heating regions in accordance with the size of a heated object; A plurality of induction coils that are distributed in the axial direction and arranged to face each heating region of the heating roller, respectively, each induction coil includes a plurality of unit induction coils connected in parallel, An induction coil device in which the number of coil turns of the unit induction coil differs depending on the heating region; a high-frequency power source that supplies high-frequency power to the induction coil device; and a high-frequency power that is supplied to each induction coil of the induction coil device And an induction coil selection means for switching the heating area of the heating roller.

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

  <Regarding Heating Roller> The heating roller is configured to be magnetically coupled to an induction coil described later to generate heat by an induced current, and to be switched to a plurality of heating regions as will be described later. The heating roller includes a secondary coil that forms a closed circuit, and the secondary coil is magnetically coupled to the induction coil, for example, an air-core transformer. In the latter case, the secondary resistance value of the closed circuit has a value substantially equal to the secondary reactance of the secondary coil. The secondary resistance value and the secondary reactance are “substantially equal” means that when the secondary resistance value is Ra, the secondary reactance is Xa, and α = Ra / Xa, Equation 1 The range is satisfactory. The reason for defining the mathematical condition is disclosed in Patent Document 3. Further, the secondary resistance value can be obtained by measurement. The secondary reactance can be obtained by calculation. Furthermore, α is preferably in the range of 0.25 to 4 times, and most preferably in the range of 0.5 to 2 times.

(Formula 1)
0.1 <α <10
Moreover, the heating roller can arrange | position single or multiple secondary coils. When providing a plurality of secondary coils, it is desirable to disperse them in the axial direction of the heating roller. In order to support the secondary coil, a roller base made of an insulating material can be used. And a secondary coil can be arrange | positioned in the outer surface of a roller base | substrate, an inner surface, or the inside of a roller base | substrate.

  Furthermore, the heating roller is divided into a plurality of heating regions along the axial direction in accordance with the size of the object to be heated. That is, when a heating roller is used for the purpose of heating a heated body such as fixing of a fixing sheet on which a toner image is formed, an appropriate heating area can be selected according to the width size of the heated body. These heating regions may not be apparently discernible, but the heating is divided by cooperation with an induction coil described later. The heating region will be described by taking the case of toner image fixing as an example. For example, when fixing a fixing body made of A4 size fixing paper on which a toner image is formed, the length of the heating region required is fixed depending on whether the fixing body is fixed vertically or horizontally. Is different. Further, for example, the required heating area width is different between the case where an A4 size fixing body is fixed and the case where a B4 size fixing body is fixed. On the other hand, it is wasteful to generate heat uniformly in areas other than the heating area necessary for fixing, and, as described above, the temperature distribution in the axial direction of the heating roller becomes non-uniform and must be avoided. . On the other hand, heat generation that is as uniform as possible is necessary in the necessary heating region. Further, even in two different heating regions, there can be a common heating region that contributes in common to any region and a single heating region that contributes only to each heating region. Furthermore, the mode of arrangement of the common heating site and the single heating site is a mode in which the common heating site is shifted to either the left or right side and the single heating site is moved to the other side, and the common heating site is centered. However, in the present invention, it is allowed to accommodate any one or all of the above.

Furthermore, the secondary coil can be formed of a conductor such as a conductor layer, a conductive wire, or a conductive plate. In order to obtain a desired secondary resistance value, the conductor layer can employ the following materials and manufacturing methods. In the case of forming by a thick film formation method (coating + firing), it is preferable to use a material selected from the group consisting of Ag, Ag + Pd, Au, Pt, RuO ₂ and C. As a coating method, a screen printing method, a roll coater method, a spray method, or the like can be used. On the other hand, in the case of forming by plating, vapor deposition or sputtering, it is preferable to use a material selected from the group of Au, Ag, Ni and Cu + (Au, Ag). For the conductive wire and the conductive plate, Cu, Al, or the like can be used. In the case of Cu and Al, in order to prevent oxidation, it is preferable to form a rust preventive film on the surface. When the roller base is made of Fe or SUS (stainless steel), the surface layer of the roller base acts as a secondary coil due to the high-frequency skin effect. Therefore, the special secondary coil as described above may not be provided. However, even in this case, if necessary, a secondary coil can be provided separately from the roller base. Note that a rust preventive film such as a zinc film can be formed on the surface of a roller base made of Fe or SUS.

  Next, in order to obtain a more practical heating roller, it is allowed to add the following configuration as necessary.

  1. (Regarding the Roller Base) In order to support the secondary coil, a roller base made of an insulating material can be used. In this case, the secondary coil can be disposed on the outer surface, the inner surface, or the inside of the roller base. The insulating roller base can be formed using ceramics or glass. In consideration of the heat resistance, strong impact and mechanical strength of the roller base, for example, the following materials can be used. Examples of the ceramic include alumina, mullite, aluminum nitride, and silicon nitride. Examples of the glass include crystallized glass, quartz glass, and Pyrex (registered trademark).

  2. (Regarding Thermal Diffusion Layer) The thermal diffusion layer can be disposed on the upper side of the conductor layer as necessary as a means for improving the temperature uniformity in the axial direction of the heating roller. For this reason, it is preferable to use a material having good heat conduction in the axial direction of the heating roller for the heat diffusion layer. Substances with high thermal conductivity are often found in metals with high conductivity such as Cu, Al, Au, Ag and Pt. However, the thermal diffusion layer only needs to have a thermal conductivity equal to or higher than that of the material of the conductor layer. Therefore, the heat diffusion layer may be the same material as the conductor layer.

  Further, when the heat diffusion layer is made of a conductive material, it may be in conductive contact with the conductor layer, but it also has an effect of blocking radiation noise radiation by being disposed through an insulating film. Since the high frequency magnetic field does not act up to the heat diffusion layer, a secondary current that contributes to heat generation is not induced in the heat diffusion layer.

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

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

  5). (Regarding Rotation Mechanism of Heating Roller) As a mechanism for rotating the heating roller, a known configuration can be appropriately selected and employed. When the toner image is heat-fixed, a pressure roller is disposed in front of the heating roller, and the toner is heated when the recording medium on which the toner image is formed passes between the two rollers. It can be configured to be fused to a recording medium.

  <Induction Coil Device> In the present invention, the “induction coil” requires a heating roller by interlinking the generated magnetic flux with the heating roller to induce a secondary current in the heating roller and generating resistance heat. And a plurality of them are distributed in the axial direction of the heating roller. The plurality of induction coils are collectively referred to as an induction coil device.

  In addition, the plurality of induction coils are dispersed in the axial direction of the heating roller, and are arranged to face each heating region of the heating roller. Each induction coil includes a plurality of unit induction coils connected in parallel, and the number of coil turns of the unit induction coil differs depending on the heating region.

  The induction coil device is energized or excited directly from a high-frequency power source, which will be described later, or via a matching circuit and / or a high-frequency transmission line, and is magnetically coupled to a heating roller, for example, an air-core transformer, but is connected to a rotating heating coil. It may be stationary with respect to it, or may be rotated together with or separately from the heating roller. In the case of rotation, a rotating current collecting mechanism may be interposed between the frequency variable high frequency power source and the induction coil. The “air-core transformer coupling” means not only a complete air-core transformer coupling but also a transformer coupling that can be substantially regarded as an air-core. However, if necessary, eddy current loss heating type electromagnetic coupling may be used.

  In addition, the induction coil device can be provided with a coil bobbin described later in order to support the induction coil. The coil bobbin can be formed with a winding groove for supporting the induction coil in an aligned winding state. The coil bobbin can be made hollow so as to pass through a high-frequency transmission line connected to the induction coil. However, a plurality of induction coils can be maintained in a predetermined shape by directly forming or bonding the induction coils with synthetic resin or glassy material instead of the coil bobbin.

  Further, the plurality of induction coils of the induction coil device can be connected in parallel to a common high-frequency power source. However, if necessary, a plurality of induction coils may be connected in series. Further, the induction coils may be individually or grouped and connected to individual high frequency power sources. In any embodiment, the power supply lead wire for supplying high frequency power from the high frequency power source to the induction coil is preferably arranged at a position close to the inner surface or the outer surface of the induction coil. When passing the power supply lead wire inside the induction coil, if the power supply lead wire is close to the central axis of the induction coil, the amount of magnetic flux interlinking with the power supply lead wire increases. Since efficiency falls, it is not preferable. On the other hand, by configuring as described above, the magnetic flux interlinking with the power supply lead wire is reduced, so that a reduction in power transmission efficiency is relatively suppressed.

  Furthermore, each of the plurality of induction coils includes a plurality of unit induction coils connected in parallel, and the number of coil turns of the unit induction coil differs depending on the heating region. According to this configuration, the high-frequency power supplied to each heating region of the heating roller can be easily controlled as desired. In the present invention, a “unit induction coil” has a predetermined axial length, number of turns, and coil diameter of a heating roller, and when a predetermined high frequency voltage is applied, a predetermined high frequency power is input as a unit. It is comprised so that. Therefore, high-frequency power having a value obtained by multiplying high-frequency power input to one unit induction coil by the number of unit induction coils can be input to the opposed heating regions.

  The reason why the number of coil turns of the unit induction coil differs depending on the heating region of the heating roller in which the unit induction coil is disposed as described above is to supplement the temperature rise characteristics of the heating region in a required direction. For example, in a heating roller configured to be rotatably supported at both ends, in the case of an induction coil disposed in a heating region at both ends, the heating roller is heated because both ends of the heating roller are deprived of heat by a bearing. The temperature drop in the zone is more severe than in the other heating zones. For this reason, it is necessary to raise the heating efficiency with respect to the heating area | region of both ends. According to the present invention, in order to cope with such a case, the number of coil turns of the unit induction coil of the induction coil disposed in the heating region at both ends is set to the number of coil turns of the unit induction coil in the other heating region. It can be made to respond appropriately by making more. Thereby, the high frequency electric power supplied into the heating area | region of the both ends of a heating roller can be increased, and heating efficiency can be made high.

  Moreover, when it is the structure which always uses the center part of a heating roller to heat a to-be-heated body, the temperature fall of the heating area | region of a center part will become intense with the to-be-heated body heating. For this reason, it is necessary to increase the heating efficiency by increasing the amount of high-frequency power supplied to the central heating region. According to the present invention, in order to cope with such a case, it is appropriate to set the number of coil turns of the induction coil disposed in the central part to be larger than the number of coil turns of the unit induction coil in other heating regions. It can be made to correspond. Thereby, the high frequency electric power input into the heating area | region of the intermediate part of a heating roller can be increased, and heating efficiency can be made high.

  The degree to which the number of coil turns of the unit induction coil arranged in a specific heating area is larger than that of other heating areas may be determined according to the necessity in each heating area. However, generally, it can be determined within a range of about 5 to 25%. Moreover, it can select within the range of preferably 10 to 20%. It is not necessary to change the coil diameter of the unit induction coil. However, when the interval between coil turns is made constant, the coil shaft length changes in proportion to the number of coil turns.

  On the other hand, the high-frequency power supplied to the induction coil is approximately proportional to the application time of the high-frequency voltage to the induction coil when the high-frequency power source is shared. Therefore, the value of the high frequency power can be individually controlled by controlling the application time of the high frequency voltage to the plurality of induction coils facing the plurality of heating regions by PWM control or the like as desired.

  <About the high frequency power source> The high frequency power source generates a high frequency power to energize each induction coil facing the plurality of heating regions in order to heat the plurality of heating regions of the heating roller as required. This is supplied to the induction coil. Further, the output frequency (or range thereof) of the high frequency power supply is not basically limited, but in the case of a transformer system, it is effective to be configured to output a high frequency of 1 MHz or more. This is because by increasing the frequency to 1 MHz or higher, it is possible to increase the Q of the induction coil and further increase the power transmission efficiency. When the power transmission efficiency is increased, the overall efficiency of heating is increased and power saving can be achieved. However, in practice, by setting the frequency to 15 MHz or less, the problem of radiation noise can be avoided as easily as possible. Note that the frequency is preferably 1 to 4 MHz from the viewpoint of the economical efficiency of a suitable active element (for example, a MOSFET can be used as described later) and the ease of suppressing high-frequency noise. Furthermore, the present invention may be an eddy current coupling method (eddy current heating method), in which case a frequency in the range of 20 to 100 kHz is suitable.

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

  Furthermore, the high frequency power supply can be arranged in common for the plurality of induction coils. However, if necessary, it is allowed to arrange a plurality of high-frequency power sources individually or in groups with respect to the plurality of induction coils.

  Furthermore, the output frequency of the high frequency power supply may be constant or variable. When the induction coil selection means to be described later comprises a filter means or a resonance circuit, it is necessary to make the output frequency of the high frequency power supply variable. In order to make the output frequency of the high-frequency power source variable, for example, known frequency variable means such as making the oscillation frequency of the excitation circuit variable can be used. In addition, if necessary, for example, it is possible to perform rapid heating by making the input power at the time of startup larger than that at the time of normal operation.

  <Induction Coil Selection Unit> The induction coil selection unit is a unit that controls the high frequency output of the high frequency power source to be selectively supplied to a desired induction coil, and is effective when switching the heating region of the heating roller. It is. The induction coil selection means can be constituted by, for example, a filter means, a resonance circuit, or a switch means. If there is one or a plurality of induction coils for which high frequency power is to be constantly supplied among the plurality of induction coils, the induction coil selection means may not be interposed between the induction coil and the high frequency power source. However, the remaining induction coils are configured such that the supply of high-frequency power is controlled by the intervening induction coil selection means.

  Moreover, the application time of the high frequency voltage with respect to an induction coil can be changed by using an induction coil selection means. This makes it possible to make the high frequency power supplied per unit length of the first and second induction coils the same, or to change the input power per unit length. In order to control the application time of the high-frequency voltage, for example, PWM control can be performed in addition to the change in frequency. Thereby, even if it is seemingly the same application time, the actual application time when the high frequency power is actually input can be made different. Further, the PWM control may be performed for each half cycle of the high frequency, or may be performed at a relatively low frequency, for example, about 1 to 100 Hz.

  Hereinafter, each configuration example of the induction coil selection unit will be described.

  (1) (Configuration by Filter Unit) The filter unit is interposed between the variable frequency type high frequency power source and the induction coil. And by changing the frequency of the high frequency applied to the filter means, it is possible to selectively supply high frequency power mainly to a desired one or a plurality of induction coils among the plurality of induction coils.

  (2) (Configuration with Resonant Circuit) The resonant circuit is configured with an induction coil as a resonant circuit element. Since the induction coil mainly includes an inductance, a resonance circuit can generally be configured by adding a capacitor. The resonance circuit may be either a series resonance circuit or a parallel resonance circuit with respect to the variable frequency type high frequency power supply. In the former, a series connection circuit of an induction coil and a capacitor is connected to a variable frequency type high frequency power supply. The latter connects a parallel circuit of an induction coil and a capacitor to a variable frequency type high frequency power supply. However, if necessary, inductance can be added in addition to the induction coil. When a plurality of resonance circuits including the first and second induction coils as resonance circuit components are configured, their resonance frequencies are differentiated into at least two types.

  Furthermore, if necessary, the magnitude of Q as selectivity can be configured to have at least two different values together with the resonance frequency between a plurality of resonance circuits.

  (3) (Configuration by switch means) The switch means may be either a contact type or a contactless type. In general, the switch means is connected to the induction coil in series. However, if necessary, the switch means is connected in parallel and the induction coil is short-circuited to cut off the supply of high-frequency power to the induction coil. You may comprise. In the latter connection mode, a plurality of induction coils are allowed to be connected in series to a high frequency power source.

  By the way, according to the present invention, the induction coil is constituted by a unit induction coil, and in the induction coil facing a predetermined heating region, the number of coil turns of the unit induction coil is unit induction of the induction coil facing the other heating region. Since it is configured differently from that of the coil, it is possible to heat the heating roller with heating efficiency corresponding to the heating area without adjusting the circuit side. It is permissible to adjust the high-frequency power input every time. As a result, the desired heating region can be heated more smoothly and as required. For example, when the object to be heated is heated by using a part of the heating region of the heating roller, the induction coil selection means selects not only the induction coil facing the heating region but also the remaining induction if desired. A high frequency power can also be distributed to a coil at a predetermined rate. Thereby, it is possible to keep the temperature at almost the same temperature as the heating area in which the unused heating area is used. Here, the “predetermined ratio” is expressed as a ratio with respect to each unit induction coil between one heating area and the remaining heating area of the heating roller, and at the same time, one of a plurality of heating areas. When the portion is used for heating the heated object, it is expressed as a limit value and a range beyond which a practically uniform temperature distribution can be obtained in the axial direction of the heating roller. For example, when three heating regions including an intermediate portion and both end portions are set on the heating roller, when heating is performed using the intermediate heating region, a high frequency is applied to the opposing induction coil at a ratio of 0.7 or more. It is preferable to apply power and distribute the high frequency power to the remaining heating area at a rate of less than 0.3. Moreover, when heating a to-be-heated body using the whole heating area | region, it is good to distribute high frequency electric power in the ratio of 0.5 or more to the heating area | region of both ends. However, it is practical that the ratio of one heating region for heating the object to be heated to 0.95 is the upper limit. At this time, the same ratio of the remaining heating region is 0.05 or less. Further, even if the predetermined ratio is constant, the total amount of high-frequency power input to the heating region changes according to the axial length of the heating region.

  (1) (PWM control system) The PWM control system is supplied to each induction coil by changing the application time of the high-frequency voltage to the plurality of induction coils facing each heating region of the heating roller by PWM control. In this method, the high-frequency power is changed at a desired rate. The PWM control may be performed every half cycle of the high frequency, or the high frequency output of the high frequency power supply may be modulated at a relatively low frequency, for example, about 1 to 100 Hz.

  (2) (In the case of a filter system) When the filter characteristic of the filter means is a band-pass type, if the variable high-frequency power supply is controlled so that the variable high-frequency power supply outputs the frequency of the passband, the induction connected to the filter means Since the coil is energized by the high-frequency power that has passed through the filter means, the region of the heating roller facing the induction coil can be heated selectively or at a predetermined ratio. Therefore, for example, in order to selectively change the energizing ratio of two induction coils depending on the frequency, two filter means having different pass bands are prepared, one of which is connected to one induction coil and the other is connected to the other. The output frequency of the frequency variable high-frequency power source may be switched so as to be within the respective pass bands, and the pass bands may be set so as to partially overlap at a predetermined rate.

  (3) (In the case of a resonance circuit) When a plurality of resonance circuits including the first and second induction coils as resonance circuit components are configured, the resonance frequencies are made to differ by at least two types and resonance characteristics Set so that the curves partially overlap. Then, the frequency of the high-frequency power source may be set so as to output high-frequency power having a frequency that resonates appropriately with respect to a plurality of resonance circuits having the respective induction coils as resonance elements.

  <About the Action of the Present Invention> In the present invention, a specific one is selected by energizing one or a plurality of induction coils arranged to face a plurality of heating regions of the heating roller. Alternatively, if a plurality of heating regions are heated and the object to be heated is passed through the heating regions, the heating can be performed to a required degree. Here, selecting a plurality of induction coils means that some or all induction coils of the entire induction coil device are included.

  Further, each of the plurality of induction coils is constituted by a plurality of unit induction coils, and the number of coil turns of the unit induction coil differs depending on the heating region, so that adjustment is not required on the circuit side such as a high frequency power source. A specific heating area can be heated as required. That is, since the amount of high frequency power input varies depending on the number of coil turns of the unit induction coil, for example, when the number of coil turns in a specific induction coil is increased, the amount of high frequency power input to the induction coil increases. As a result, the heating efficiency of the heating region facing the induction coil, that is, the degree of temperature rise of the heating roller per second is improved, so that desired heating characteristics can be obtained.

  In the present invention, among a plurality of heating regions, a specific heating region where an induction coil whose number of coil turns of the unit induction coil is different from that of the unit induction coil in the other heating region is opposed to only the heating region. In this case, the desired action and effect can be obtained both in the case of heating and in the case of heating simultaneously with a plurality of heating regions.

<About 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.

  1. (Warm-up control) During the warm-up period after the start-up, that is, the start of power supply, the heating roller can be controlled to rotate at a lower rotational speed than during normal operation.

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

  3. (Conveying sheet) When heating the heated object using the heating roller, the heating roller can be configured to directly contact the heated object, but if necessary, the conveying sheet is interposed between the two. It can be constituted as follows. In this case, the conveyance sheet is allowed to take an endless or roll shape. By using the conveyance sheet, it becomes possible to smoothly heat and convey the heated object.

    An induction heating roller device according to a second aspect of the present invention includes a first heating region located at an intermediate portion and a second heating region located at both ends while being magnetically coupled to an induction coil device, which will be described later, and generating heat by an induced current. A heating roller having a first induction coil disposed opposite to the first heating region of the heating roller and a second induction coil disposed opposite to the second heating region, each induction The coil includes a plurality of unit induction coils connected in parallel, and the number of coil turns of the unit induction coil in the second induction coil is greater than the number of coil turns of the unit induction coil in the first induction coil. A coil device; a high-frequency power source that supplies high-frequency power to the induction coil device; and a high-frequency power that is supplied to each induction coil of the induction coil device to control the heating region of the heating roller It is characterized in that it comprises a; and obtaining the induction coil selection means.

  The present invention defines the configuration of an induction heating roller device suitable for maintaining a uniform temperature along the axial direction of the heating roller in a heating roller having a double-end support structure.

  The heating area in the middle part of the heating roller is allowed to consist of a single or a plurality of heating areas. When it consists of a several heating area | region, it can comprise so that it can heat individually by an induction coil selection means, or grouping thru | or common.

  Thus, according to the present invention, it is possible to increase the high-frequency power input to the heating regions at both ends of the heating roller to increase the heating efficiency, thereby making the temperature distribution along the axial direction of the heating roller uniform. Can be held in.

    An induction heating roller device according to a third aspect of the present invention includes a first heating region located at an intermediate portion and a second heating region located at both ends while being magnetically coupled to an induction coil device described later and generating heat by an induced current. A heating roller having a first induction coil disposed opposite to the first heating region of the heating roller and a second induction coil disposed opposite to the second heating region, each induction The coil includes a plurality of unit induction coils connected in parallel, and the number of coil turns of the unit induction coil in the first induction coil is greater than the number of coil turns of the unit induction coil in the second induction coil. A coil device; a high-frequency power source that supplies high-frequency power to the induction coil device; and a high-frequency power that is supplied to each induction coil of the induction coil device to control the heating region of the heating roller It is characterized in that it comprises a; and obtaining the induction coil selection means.

  The present invention defines a configuration of an induction heating roller device that is suitable for the case where the heating region at the intermediate portion of the heating roller is always used.

  Thus, according to the present invention, it is possible to increase the high-frequency power input to the heating area in the middle part of the heating roller and increase the heating efficiency. The temperature distribution along the axial direction of the heating roller can be kept uniform.

    An induction heating roller device according to a fourth aspect of the present invention is a heating roller that is magnetically coupled to an induction coil device, which will be described later, and generates heat by an induced current; And an induction coil device in which the closest portion is formed between the inner surface of the heating roller and a high frequency power source for supplying high frequency power to the induction coil.

  The description in claim 1 applies mutatis mutandis to the heating roller and the high-frequency power source. Note that the heating roller may include a single heating region. In addition, when the heating roller includes a plurality of heating regions, the induction coil selection means in claim 1 can be used.

  The induction coil device includes a single or a plurality of induction coils. When the induction coil device includes a plurality of induction coils, each induction coil is allowed to correspond to the plurality of heating regions of the heating roller on a one-to-one basis. Moreover, the induction coil arrange | positioned facing one heating area | region can be comprised with the several unit induction coil connected in parallel. In addition, about the unit induction coil, the description in Claim 1 applies mutatis mutandis. In this case, the induction coil facing each of the plurality of heating regions may be a unit induction coil having a common specification for all induction coils.

  The induction coil device is disposed in an off-center relationship inside the heating roller and is magnetically coupled to the heating roller. Therefore, the closest part is formed in the distance between the inner surface of the heating roller and the induction coil device.

  Thus, in the present invention, since the above configuration is provided, the heating roller has a magnetic coupling between the induction coil device and the heating roller at the closest portion between the inner surface thereof and the induction coil device. Become stronger. For this reason, heat generation is concentrated at the closest part. Therefore, it can be configured to heat the object to be heated using the vicinity of the heat generation concentrated portion. Thereby, since heating efficiency improves, energy saving can be aimed at. Moreover, heating performance improves by heating a to-be-heated body using the high temperature rise in the closest part.

  On the other hand, in this type of conventional induction heating roller device, the induction coil is arranged around the axis of the heating roller. In this case, the heat generated by the heating roller becomes uniform around its axis. Therefore, it is difficult to concentrate the entire heat generated by the heating roller for heating the object to be heated.

    According to a fifth aspect of the present invention, there is provided a fixing device main body provided with a pressure roller; a heating roller and a pressure roller of the fixing device main body are provided in a pressure contact relationship, and a toner image is formed between the two rollers. An induction heating roller device according to any one of claims 1 to 4, which is disposed so as to fix a toner image while being conveyed with a recording medium interposed therebetween.

  In the present invention, the “fixing device main body” refers to the remaining portion of the fixing device excluding the induction heating roller device.

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

  In the present invention, the recording medium corresponds to the object to be heated in the inventions of claims 1 to 4.

  Thus, in the present invention, it is possible to effectively fix the recording medium on which the toner image is formed by utilizing the action of the induction heating roller device according to claims 1 to 4.

    According to a sixth aspect of the present invention, there is provided a fixing device main body provided with a pressure roller; a heating roller and a pressure roller of the fixing device main body are provided in a pressure contact relationship, and a toner image is formed between the two rollers. It is arranged so as to fix the toner image while being conveyed with the recording medium interposed therebetween, and is arranged so as to heat the object to be heated using the heat of the closest part between the heating roller and the induction coil. And an induction heating roller device according to claim 4.

  In the present invention, if the closest part between the induction coil and the inner surface of the heating roller is directly opposed to the pressure roller, or if it is slightly forward in the rotational direction of the heating roller, high heat generated in the closest part The object to be heated can be effectively heated using

  Thus, according to the present invention, the object to be heated can be effectively heated in spite of the low high frequency power.

    According to a seventh aspect of the present invention, there is provided a fixing device main body provided with a pressure roller; a heating roller and a pressure roller of the fixing device main body are provided in a pressure contact relationship, and a toner image is formed between the two rollers. It is arranged so that the toner image is fixed while being conveyed with the recording medium sandwiched, and the closest part between the heating roller and the induction coil is ahead of the contact part between the heating roller and the pressure roller in the rotation direction of the heating roller. And an induction heating roller device according to claim 4.

  The present invention defines a configuration suitable for improving the fixing performance when the fixing device is configured using the induction heating roller device of the invention defined in claim 4. That is, with the above configuration, the contact portion of the heating roller can be heated to a high temperature when the heated body is heated. Note that “the closest part between the heating roller and the induction coil is located in front of the contact portion between the heating roller and the pressure roller in the rotation direction of the heating roller” means that the pressure roller of the heating roller is correct. It means that it has shifted | deviated from the site | part to the front position with respect to the rotation direction of a heating roller. The forward position is an effective range in which a high temperature can be obtained. Specifically, although it depends on design conditions such as the rotational speed on the peripheral surface of the heating roller, it generally exceeds 0 °. It should just be in the range of -90 degrees. However, it is preferably in the range of 5-60 °.

  Thus, according to the present invention, heating efficiency is improved and heating can be performed at a high temperature, so that fixing performance is improved.

    An image forming apparatus according to a seventh aspect of the invention comprises: an image forming apparatus main body provided with an image forming means for forming a toner image on a recording medium; and the toner image on the recording medium disposed on the main body of the image forming apparatus. And a fixing device described in item 6 or 7.

  In the present invention, the “image forming apparatus main body” refers to the remaining part of the image forming apparatus excluding the fixing device. The image forming means is means for forming an image for forming image information on the recording medium by an indirect method or a direct method. The “indirect method” is a method of forming an image by transfer.

  Examples of the image forming apparatus include an electrophotographic copying machine, a printer, and a facsimile.

  Examples of the recording medium include a transfer material sheet, printing paper, electrofax sheet, and electrostatic recording sheet.

    According to claim 1, a plurality of heating regions can be selectively set in the axial direction of the heating roller, and the temperature of the heating region is adjusted to a desired value without adjusting on the circuit side, and the heating roller Thus, it is possible to provide an induction heating roller device having good heating characteristics in a desired heating region.

    According to the second aspect of the present invention, the induction heating roller device that uniformly maintains the temperature distribution along the axial direction of the heating roller by increasing the high-frequency power supplied to the heating regions at both ends of the heating roller to increase the heating efficiency. Can be provided.

    According to the third aspect of the present invention, the high-frequency power supplied to the heating area at the intermediate portion of the heating roller is increased to increase the heating efficiency, and the intermediate heating area is always used along the axial direction of the heating roller. An induction heating roller device that maintains a uniform temperature distribution can be provided.

    According to the fourth aspect of the present invention, the heating roller concentrates heat at the part where the induction coil device is approaching, so that the heating efficiency is improved by heating the object to be heated using the vicinity of the concentrated portion of the heat generation. It is possible to provide an induction heating roller device that is improved and saves energy.

    According to the fifth aspect, it is possible to provide a fixing device that has the effect of the fourth aspect and has a good fixing performance and fixes a toner image at a high speed.

    According to the sixth and seventh aspects, it is possible to provide a fixing device that has the effect of the fourth aspect and has a further excellent fixing performance and fixes a toner image at a high speed.

    According to the eighth aspect of the present invention, the effect of the first to fifth aspects is obtained, and the warm-up of the heating roller is accelerated by induction heating, so that an image forming apparatus suitable for a high-speed type can be obtained.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

    1 to 8 show a first embodiment for carrying out the induction heating roller device of the present invention, FIG. 1 is a circuit block diagram showing the outline of the whole device, and FIG. 2 shows one of the induction coil device and the heating roller. FIG. 3 is a cross-sectional front view of the induction coil device and the heating roller, FIG. 4 is a conceptual diagram illustrating the relationship between the position of the heating roller and the induction coil device, and the temperature distribution of the heating roller, and FIG. FIG. 6 is a circuit diagram showing a power supply main circuit section and a frequency control section of a high-frequency power source, FIG. 7 is a circuit diagram of an output circuit and induction coil selection means, and FIG. It is a graph which shows notionally the frequency-high frequency electric power characteristic which shows the relationship between the high frequency electric power thrown into a 2nd induction coil, and an output frequency. This embodiment complies with claims 1 and 2. The induction heating roller device includes a heating roller HR, an induction coil device IC, a high frequency power supply HFS, and induction coil selection means PAM. Further, as shown in FIG. 2, the heating roller HR includes a rotation mechanism RM, and is driven and rotated by the rotation mechanism RM. Hereafter, the structure is demonstrated in detail for every said component.

  <Heating roller HR> The heating roller HR includes a roller base 1, a secondary coil ws, and a protective layer 2, and is rotated by a rotation mechanism RM. The roller base 1 is made of a cylindrical body made of alumina ceramic, and has a length of 300 mm and a thickness of 3 mm, for example. The secondary coil ws is composed of a cylindrical one-turn coil in the form of a film made of a vapor deposition film of Cu, and is disposed on the outer surface of the roller base 1 over almost the entire effective length in the axial direction. The thickness of the secondary coil ws is set so that the value of the secondary resistance R in the circumferential direction of the heating roller HR becomes 1Ω, which is substantially the same value as the secondary reactance. The protective layer 2 is made of a fluororesin and is formed so as to cover the outer surface of the secondary coil ws.

  The rotation mechanism RM is a mechanism for rotating the heating roller HR, and is configured as follows. That is, as shown in FIG. 2, the first end member 3A, the 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, a drive shaft 3b, and a pointed end portion 3c. The cap portion 3a is fitted to the left end of the heating roller HR from the outside in FIG. 2 and is fixed to the heating roller HR using a push screw (not shown) to support the left end of the heating roller HR. Yes. The drive shaft 3b protrudes outward from the center portion of the outer surface of the cap portion 3a. The pointed portion 3c protrudes inward of the cap portion 3a from the center portion of the inner surface of the cap portion 3a. The second end member 3B includes a ring portion 3d. The ring portion 3d supports the right end of the heating roller HR by fitting from the outside to the right end of the heating roller HR in FIG. 2 and fixing the heating roller HR to the heating roller HR using a push screw (not shown). Yes. One of the pair of bearings 4 and 4 rotatably supports the outer surface of the cap portion 3a in the first end member 3A. The other supports the outer surface of the second end member 3B rotatably. Therefore, the heating roller HR is rotatably supported by the first and second end members 3A and 3B fixed to both ends thereof and the pair of bearings 4 and 4. The bevel gear 5 is attached to the drive shaft 3b of the first end plate 3A. The spline gear 6 meshes with the bevel gear 5. The motor 7 has a rotor shaft directly connected to the spline gear 5.

  <Induction Coil Device IC> The induction coil device IC includes first and second induction coils IC1 and IC2, and is disposed coaxially within the heating roller HR. As shown in FIGS. 4 and 5, the first induction coil IC <b> 1 is disposed to face the heating area A in the middle part of the heating roller HR. On the other hand, the second induction coil IC2 is shown as being assembled in FIG. 1, but actually, as shown in FIGS. 4 and 5, the second induction coil IC2 is slightly attached to both ends of the first induction coil IC1. Are disposed adjacent to each other with a predetermined insulation distance, and opposed to the heating region B distributed at both ends of the heating roller HR. Therefore, the second induction coil IC2 is distributed and arranged at both ends of the heating roller HR.

The first and second induction coils IC1 and IC2, as shown in FIGS. 4 and 5, respectively configured in parallel connecting a plurality of units derived coil _IC U 1, IC _U 2, the heating roller HR Each of the secondary coils ws is magnetically coupled. Then, as shown in FIG. 5, the first and second induction coils IC1 and IC 2, and in each of the units derived coil _IC U 1, IC _U 2, is opposite to each other winding direction of adjacent ones, and The generated magnetic flux is set to have the same polarity. In FIG. 5, the number of coil turns of the unit induction coils IC _U 1 and IC _U 2 is shown to be the same for convenience, but actually differs as shown in FIG. The first inductive coil IC1, as shown in FIG. 4, consists of induction of six units connected in parallel coil IC U _1. Each unit induction coil IC _U 1 has a number of coil turns in the range of 25 to 30, for example, 25 turns. The distance between the unit induction coil IC U ₁ adjacent and between coil turns of units derived coil IC U ₁ is set in both example 1 mm.

In contrast, the second induction coil IC 2, IC 2 is comprised of respectively parallel connected three unit induction coil IC _U 2. Each unit induction coil IC _U 2 is the number of coil turns is in the range of 29-35, is set to, for example, 29 turns. The distance between the unit induction coil IC U ₂ of coil turns and between adjacent unit induction coil are both set in the same manner as example 1mm as in the first induction coil IC1. The distance s between the first induction coil IC1 and second induction coils IC2 are wide for example 4mm than the spacing between the first and second units induction coil _IC U 1, IC _U 2 of coil turns Is set.

  Further, as shown in FIGS. 2 and 3, the first and second induction coils IC1 and IC2 are wound around the coil bobbin 8 and are distributed in the axial direction of the heating roller HR. The first induction coil IC1 is connected between the power supply leads 9a and 9d, and the second induction coil IC2 is divided into two parts, one of which is between the power supply lines 9b and 9d and the other is 9c. Each is connected between 9d. The four power supply lead wires 9a to 9d are connected to the output terminal of a high frequency power supply HFS described later via the induction coil selection means PAM.

  The coil bobbin 8 is made of, for example, a fluororesin cylindrical body, and has a concave portion 8a, a support portion 8b, and a through groove 8c. The concave portion 8a is formed at the center of the tip of the coil bobbin 8, and is relatively rotatably locked to the rotation mechanism RM. The support portion 8b is formed at the proximal end of the coil bobbin 8, and is fixed to a fixing portion (not shown). The through-groove 8c is formed in a hook shape along the axial direction in a part of the outer surface of the coil bobbin 8, and accommodates the feed lead wires 9a to 9d therein. As shown in FIG. 3, the power supply lead wires 9 a to 9 d are housed in the through-groove 1 c and led out from the base end side of the coil bobbin 8 to the outside.

  Thus, the first and second induction coils IC1 and IC2 are used in a stationary state, and the feed lead wires 9a to 9d are housed in the through-grooves 1c and approach each induction coil IC1IC2. Since there is almost no interlinkage of magnetic flux, almost no eddy current loss occurs in the feed lead 9.

  On the other hand, the first and second induction coils IC1 and IC2 are inserted into the heating roller HR from the ring portion 3d of the second end member 3B, and the concave portion 1a formed at the tip of the coil bobbin 1 is the first. The end portion 3c of the first end plate 3A is engaged with the support portion 1b formed at the base end as described above and is fixed to the fixing portion, thereby being supported in a coaxial relationship with the heating roller HR, Even if the heating roller HR rotates, the stationary state is maintained.

  <High Frequency Power Supply HFS> As shown in FIGS. 1 and 6, the high frequency power supply HFS includes a power supply main circuit section MC, an output circuit OC, and a frequency control section FC.

    (Power Supply Main Circuit Unit MC) As shown in FIG. 6, the power supply main circuit unit MC includes a low frequency power supply AS, a DC power supply RDC, and a high frequency generation unit HFI. The low frequency AC power supply AS is composed of, for example, a 100V commercial AC power supply. The DC power supply RDC is composed of a rectifier circuit, the input terminal is connected to the low frequency AC power supply AS, converts the low frequency AC voltage into a non-smooth DC voltage, and outputs it from the DC output terminal. The high frequency generator HFI includes a high frequency filter HFF and a half-bridge inverter main circuit HBI. The high frequency filter HFF includes a pair of inductors L1 and L2 in series on both lines, and a pair of capacitors C1 and C2 connected between the lines before and after the pair of inductors L1 and L2, and includes a DC power supply RDC and a half described later. It is interposed between the bridge-type inverter main circuit HBI and prevents high frequency from flowing out to the low frequency AC power supply AS side. The half-bridge inverter main circuit HBI is connected in series between the output terminals of the DC power supply RDC and is connected in parallel to a pair of MOSFETs Q1 and Q2 and a pair of MOSFETs Q1 and Q2 that are alternately switched by being excited by a drive signal of the drive circuit DC. Consists of capacitors C3 and C4. Capacitors C3 and C4 perform a high frequency bypass action during inverter operation.

    (Output Circuit OC) The output circuit OC performs substantially the same impedance by performing impedance conversion at different frequencies as a load on the high frequency power supply HFS in order to operate the high frequency power supply HFS in a state of high efficiency at each of different output frequencies. And means for efficiently outputting high-frequency power by acting so as to exhibit a phase difference. As shown in FIG. 5, the circuit includes a series circuit of a capacitor Css and an inductor Lss inserted in series on the line, and a parallel circuit of an inductor Lpp and a capacitor Cpp connected in parallel to the line at a subsequent stage of the series circuit.

  Further, since the output circuit OC is configured so that the high frequency power supply HFS includes a series resonance type half-bridge inverter main circuit HBI using a MOSFET as a switching means, the charge / discharge voltage of the MOSFET output capacitance Coss becomes 0V. Each circuit component is configured with constants that realize load conditions for commutating the output current I during the dead time dt of the switching means at different frequencies.

  Further, the output circuit has two parallel resonance points whose frequency-impedance characteristics appear at the frequencies f1 and f2, and a series resonance point where the impedance is maximized between them. In short, the output circuit OC is in a parallel resonance state at the first and second output frequencies f1 and f2.

  Furthermore, the output circuit OC has three passing points whose frequency-phase characteristics are at a phase of 0 °. There are two parallel resonance points where the frequencies f1 and f2 are at a predetermined phase angle, and a series resonance point where the impedance is maximized between them.

    (Frequency Control Unit FC) As shown in FIG. 4, the frequency control unit FC includes an oscillator OSC and a drive signal generation circuit DC. The high-frequency oscillator OSC is a variable oscillation frequency type, and is controlled by an external signal source (not shown) to generate a high-frequency excitation signal having a variable frequency and input it to the drive circuit DC. The drive circuit DC is composed of a preamplifier, and amplifies the high frequency signal sent from the high frequency oscillator OSC and outputs a drive signal.

  <Induction Coil Selection Unit PAM> As shown in FIG. 7, the induction coil selection unit PAM includes first and second frequency discrimination filter units F1 and F2. The first and second frequency discrimination filter means F1 and F2 are filter means for selectively allowing high-frequency power having a preset frequency to pass through the first induction coil IC1 connected thereto. The first and second frequency discriminating filter means F1 and F2 are seen from the capacitors CC1 and CC2 connected in series to the line, the capacitors Cpp1 and Cpp2 connected in parallel to the line, and the first and second induction coils IC1 and IC2. The induction coils IC1 and IC2 and the equivalent inductances Lc1 and Lc2 of the heating roller HR are included in a series-parallel resonance circuit. As shown in FIG. 7, the equivalent circuit of the induction coils IC1 and IC2 and the heating roller HR viewed from the induction coil side includes a parallel circuit of inductances Lc1 and Lc2 and resistors Rc1 and Rc2. Actually, the distributed capacitances are further connected in parallel. However, since this distributed capacitance is small, if the capacitances of the capacitors Cpp1 and Cpp2 are set to a value larger by one digit or more than the distributed capacitance, they can be ignored in practice. .

  Then, the frequency-high frequency voltage characteristic of the induction coil selection means PAM is as shown in FIG. 8, for example. In the figure, a curve F1 shows the characteristics of the first frequency discrimination filter means F1, and a curve F2 shows the characteristics of the second frequency discrimination filter means F2. Therefore, at the frequency f1, the first frequency discrimination filter means F1 outputs the high frequency voltage Va1 and the second frequency discrimination filter means F2 outputs the high frequency voltage Vb1. At the frequency f2, the first frequency discrimination filter means F1 outputs a high-frequency voltage Va2, and the second frequency discrimination filter means F2 outputs a high-frequency voltage Vb2.

  <Operation of 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 unit RDC in the power supply main circuit unit MC of the high-frequency power supply HFS, and further the high-frequency generation unit HFI It is converted into a voltage and output as a high frequency voltage. This high-frequency output voltage is further applied to the stationary first and second induction coils IC1 and IC2 via the output circuit OC and the induction coil selection means PAM.

  In order to use the first and second heating areas A and B of the heating roller HR simultaneously, when the first and second heating areas A and B are heated to the same temperature, an external signal source (not shown) is operated. The output frequency of the high frequency output of the high frequency power supply HFS is set to the first frequency f1, and the high frequency power supply HFS operates. At this time, as shown in FIG. 8, both of the first and second frequency discrimination filter means F1 and F2 have the same frequency-high frequency voltage characteristic of the high frequency output voltage of the first frequency f1, in other words, Since it is preset to output at a ratio of 0.5, the high-frequency output voltages Va1 and Va2 output from the first and second frequency discrimination filter means F1 and F2 are both equal.

In contrast, the second induction coil IC2 is being number of coil turns of the unit induction coil IC U ₂ as described above is set larger than that of the units derived coil IC U ₁ of the first inductive coil IC1 Therefore, the high frequency power Wb1 input from the high frequency power supply HFS to the second induction coil IC2 is larger than the high frequency power Wa1 in the first induction coil IC1. Therefore, if the heat consumption along the axial direction of the heating roller HR is uniform, the temperature of the second heating region B is higher than the temperature of the first heating region A as shown by the dotted line in FIG. Become. However, as shown in FIG. 2, both ends of the heating roller HR are rotatably supported by the bearings 4, 4, so that the heat input to the second heating region B is deprived by the bearings 4, 4. Thus, as shown by the solid line in FIG. 4, the temperature is substantially the same as the temperature of the first heating region A. As a result, the heating roller HR is heated to a uniform temperature in the axial direction thereof, so that a heated body having a size over the heating areas A and B can be heated uniformly.

  Next, even when only a first heating area A located at the center of the heating roller HR is used to heat a small object to be heated, the heating area B is maintained again by keeping the heating area B warm. When heating the object to be heated using B, heat treatment can be performed quickly without requiring a special warm-up time. In order to keep the heating region B warm in such a case, the output frequency of the high frequency power supply HFS is set to f2. Thereby, as shown in FIG. 8, the first frequency discrimination filter means F1 of the induction coil selection means PAM generates a high-frequency output voltage of relatively high Va2, and the second frequency discrimination filter means F2 is relatively Produces a low Vb2 high frequency output voltage. As a result, the high-frequency power supplied to the first and second induction coils IC1 and IC2 becomes a ratio of about 0.7: 0.3, and the second heating region B is used for heating the object to be heated. The temperature is kept at the same level as the temperature of the heating area A.

FIG. 9 is a conceptual diagram for explaining the relationship between the position of the heating roller and the induction coil device, and the temperature distribution of the heating roller, showing a second mode for carrying out the induction heating roller device of the present invention. This embodiment complies with claims 1 and 3. Note that the same parts as those in FIG. In this embodiment, the heating area A in the middle part is configured to be heated to a temperature higher than that of the both end parts for constant use. That is, the induction coil IC1 opposed to the heating region A is the coil number of turns is 30 of the unit induction coil IC _U, it is greater than the coil turns number 26 of unit induction coil IC _U of the induction coil IC2 opposed to the heating region B ing. Then, when a substantially equal high frequency voltage is applied from the high frequency power source to the induction coils IC1 and IC2, as a result, the temperature of the heating region A becomes higher than that of the heating region B as shown in FIG. In this embodiment, a relatively small heated object that uses only the heating area A and a relatively large heated object that uses both the heating areas A and B are mixed and heated. Suitable for use.

    FIG. 10 is a longitudinal sectional view showing a first embodiment for carrying out 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, 25 is a gantry, and IC is an induction coil. This embodiment complies with claim 5. The induction heating roller device 21 can use the induction heating roller device of each form shown in FIGS. The induction coil device IC and the heating roller HR are set in a coaxial relationship.

  The pressure roller 22 is disposed so as to be in pressure contact with the heating roller HR of the induction heating roller device 21 and conveys the recording medium 23 while narrowly pressing between them.

  The recording medium 23 forms an image by the toner 24 adhering to the surface thereof. The recording medium 23 has a toner image formed thereon and corresponds to a heated body.

  The gantry 25 mounts the above constituent elements (excluding the recording medium 23) in a predetermined positional relationship.

  In the fixing device, the recording medium 23 on which the toner 24 adheres and forms an image is inserted between the heating roller HR and the pressure roller 22 of the induction heating roller device 21 and conveyed. The toner 24 is heated and melted by receiving heat from the heating roller HR, and heat fixing is performed.

FIG. 11 is a conceptual cross-sectional view showing a third embodiment for implementing the induction coil device of the present invention and a second embodiment for implementing the fixing device of the present invention. This embodiment complies with claims 4 to 6. In the figure, the same parts as those in FIG. In this embodiment, the induction coil device IC is off-center with respect to the axis of the heating roller HR. Therefore, the closest part s _A is formed between the induction coil unit IC and the heating roller HR. In the present embodiment, the closest approach part s _A is disposed at a position facing the pressure roller 22. The heating roller HR fixes the recording medium 23 while rotating counterclockwise.

Then, since the induction coil device IC approaches the inner surface of the heating roller HR, the closest approach portion s _A is surrounded by a dotted line because the magnetic coupling between the two becomes strong and a lot of secondary induced current flows in the vicinity thereof. A high temperature rise is obtained in the area of the heating roller HR. As a result, the fixing performance is improved while using less high-frequency power.

FIG. 12 is a conceptual cross-sectional view showing a third embodiment for carrying out the fixing device of the present invention. In the figure, the same parts as those in FIG. This embodiment, the closest portion s _A is positioned forward approximately 45 ° in the rotational direction of the heating roller HR.

Then, since the closest part s _A is positioned forward of the rotational direction of the heating roller HR, the site which is heated strongly in the closest part s _A comes immediately position of the recording medium 23, recording medium 23 Is effectively performed.

    FIG. 13 is a conceptual cross-sectional view of a copying machine as an embodiment for carrying out the image forming apparatus of the present invention. In the figure, 31 is a reading device, 32 is an image forming means, 33 is a fixing device, and 34 is an image forming device case.

  The reading device 31 optically reads a base paper to form 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 transfers this to a recording medium such as paper. To form an image.

  The fixing device 33 has the structure shown in any one of FIGS. 10 to 12, and heat-fixes the toner adhering to the recording medium by heating and melting.

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

1 shows a first embodiment for carrying out an induction heating roller device of the present invention, and FIG. 1 is a circuit block diagram showing an outline of the entire device. Similarly, a partially cut center front view of the induction coil device and the heating roller Similarly, cross-sectional view of induction coil device and heating roller Similarly, a conceptual diagram for explaining the relationship between the position of the heating roller and the induction coil device and the temperature distribution of the heating roller The circuit diagram which similarly shows the connection aspect of an induction coil apparatus Similarly, a circuit diagram showing a power supply main circuit section and a frequency control section of a high-frequency power supply Similarly circuit diagram of output circuit and induction coil selection means Similarly, a graph conceptually showing a frequency-high frequency power characteristic showing the relationship between the high frequency power input to the first and second induction coils and the output frequency. The conceptual diagram explaining the relationship between the position of a heating roller and the induction coil apparatus which shows the 2nd form for implementing the induction heating roller apparatus of this invention, and the temperature distribution of a heating roller 1 is a longitudinal sectional view showing a first embodiment for carrying out the fixing device of the present invention. Conceptual principal part sectional drawing which shows the 3rd form for implementing the induction coil apparatus of this invention, and the 2nd form for implementing the fixing device of this invention FIG. 4 is a conceptual cross-sectional view showing a third embodiment for carrying out the fixing device of the present invention. 1 is a conceptual sectional view of a copying machine as an embodiment for carrying out an image forming apparatus according to the present invention.

Explanation of symbols

A, B ... heating region, HR ... heating roller, IC ... induction coil unit, IC1 ... first induction coil, IC 2 ... second induction _{coil, IC U 1, IC U 2} ... Unit induction coil

Claims (8)

A heating roller that is magnetically coupled to an induction coil device to be described later, generates heat by an induced current, and is switched to a plurality of heating regions according to the size of the object to be heated;
The induction coil includes a plurality of induction coils distributed in the axial direction of the heating roller and arranged to face the respective heating regions of the heating roller, and each induction coil includes a plurality of unit induction coils connected in parallel. And an induction coil device in which the number of coil turns of the unit induction coil differs depending on the heating region;
A high frequency power supply for supplying high frequency power to the induction coil device;
Induction coil selection means for controlling the high frequency power supplied to each induction coil of the induction coil device and switching the heating region of the heating roller;
An induction heating roller device comprising: A heating roller that is magnetically coupled to an induction coil device to be described later and generates heat by an induced current, and has a first heating region located at an intermediate portion and second heating regions located at both ends;
A first induction coil disposed opposite to the first heating region of the heating roller and a second induction coil disposed opposite to the second heating region, each induction coil being connected in parallel A plurality of unit induction coils, and an induction coil device in which the number of coil turns of the unit induction coil in the second induction coil is greater than the number of coil turns of the unit induction coil in the first induction coil;
A high frequency power supply for supplying high frequency power to the induction coil device;
Induction coil selection means for controlling the high frequency power supplied to each induction coil of the induction coil device and switching the heating region of the heating roller;
An induction heating roller device comprising: A heating roller that is magnetically coupled to an induction coil device to be described later and generates heat by an induced current, and has a first heating region located at an intermediate portion and second heating regions located at both ends;
A first induction coil disposed opposite to the first heating region of the heating roller and a second induction coil disposed opposite to the second heating region, each induction coil being connected in parallel An induction coil device comprising a plurality of unit induction coils, wherein the number of coil turns of the unit induction coil in the first induction coil is greater than the number of coil turns of the unit induction coil in the second induction coil;
A high frequency power supply for supplying high frequency power to the induction coil device;
Induction coil selection means for controlling the high frequency power supplied to each induction coil of the induction coil device and switching the heating region of the heating roller;
An induction heating roller device comprising: A heating roller that is magnetically coupled to an induction coil device to generate heat by an induced current;
An induction coil device in which a closest portion is formed between the inner surface of the heating roller by being arranged along the axial direction in the heating roller and off-center with respect to the axis of the heating roller;
A high frequency power supply for supplying high frequency power to the induction coil;
An induction heating roller device comprising: A fixing device body provided with a pressure roller;
A heating roller is provided in a pressure contact relationship with the pressure roller of the fixing device main body so as to fix the toner image while conveying a recording medium on which a toner image is formed between both rollers. An induction heating roller device according to any one of 1 to 4;
A fixing device. A fixing device body provided with a pressure roller;
A heating roller is disposed in pressure contact with the pressure roller of the fixing device main body, and is arranged to fix the toner image while conveying the recording medium on which the toner image is formed between both rollers, The induction heating roller device according to claim 4, which is disposed so as to heat an object to be heated using heat of a closest part between the heating roller and the induction coil;
A fixing device. A fixing device body provided with a pressure roller;
A heating roller is disposed in pressure contact with the pressure roller of the fixing device main body, and is arranged to fix the toner image while conveying the recording medium on which the toner image is formed between both rollers, The induction heating roller device according to claim 4, wherein the closest approach portion between the heating roller and the induction coil is positioned in front of the contact portion between the heating roller and the pressure roller in the rotation direction of the heating roller;
A fixing device. An image forming apparatus main body provided with an image forming means for forming a toner image on a recording medium;
A fixing device according to any one of claims 5 to 7, which is disposed in the image forming apparatus main body and fixes a toner image on a recording medium;
An image forming apparatus comprising:

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