JP2007199356A - Fixing device of electromagnetic induction heating system, and image forming apparatus equipped therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device capable of heating a fixing member at the same level, without spoiling power-heat conversion efficiency nor having to manufacture separate electromagnetic induction coils, even when the voltage of a commercial power source is switched. <P>SOLUTION: The fixing device is equipped with the fixing member and a pressure member, brought into press-contact with each other so as to form a nip through which a sheet is made to pass. The device is equipped with the electromagnetic induction coil, directly or indirectly heating the fixing member by electromagnetic induction. It is equipped with an inverter circuit, interposed between the power source and the electromagnetic induction coil and supplying an alternating current to the electromagnetic induction coil based on a control signal. The electromagnetic induction coil includes a plurality of partial coils 31 and 32, and the respective partial coils 31 and 32 have connection terminals T1 and T2; T3 and T4, connected by being switched in series or in parallel with each other. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electromagnetic induction heating type fixing device and an image forming apparatus including the same.

  In recent years, as a fixing device for fixing toner on a sheet such as paper, an electromagnetic induction heating type capable of rapid heating and high-efficiency heating has attracted attention because of demands for shortening warm-up time and energy saving. A general electromagnetic induction heating type fixing device forms a nip by pressing a fixing member (such as a roller or a belt) heated by an electromagnetic induction coil and another pressure member (such as a roller) together. The toner is fixed to the sheet by conveying the sheet to which the toner is attached through the sheet. When the fixing member is directly subjected to electromagnetic induction by the electromagnetic induction coil and heated by an eddy current (this is referred to as a direct heating method), the fixing member generates heat by receiving the electromagnetic induction by the electromagnetic induction coil. There is a case of being indirectly heated through another heat generating member (this is called an indirect heating method).

In order to energize the electromagnetic induction coil, the electromagnetic induction coil and the capacitor constitute a resonance circuit, and a high frequency alternating current from the commercial power supply to the resonance circuit via the inverter circuit (usually a frequency near the resonance frequency of the resonance circuit). It has been done by supplying The amount of heat generated by the fixing member is determined by the amount of current flowing through the electromagnetic induction coil.
Japanese Patent Laid-Open No. 9-80951 JP-A-9-106207

  By the way, as the voltage (nominal value) of the commercial power supply, two types of 100V system and 200V system are used depending on the region where the fixing device and the image forming apparatus including the same are used. When the voltage of the commercial power source is switched between the 100V system and the 200V system, in the conventional electromagnetic induction heating type fixing device, the inverter circuit uses the inverter circuit to maintain the heat generation amount of the fixing member at a target level. The power supplied to the electromagnetic induction coil is controlled by changing the frequency of the alternating current.

  However, in the electromagnetic induction heating method, the power-heat conversion efficiency is set to be high when the frequency of the alternating current applied to the electromagnetic induction coil is set in the vicinity of the resonance frequency of the resonance circuit. When the frequency of the alternating current is simply switched according to the voltage of the commercial power supply by the inverter circuit, there is a problem that the power-heat conversion efficiency is lowered.

  In addition, it is inconvenient to prepare a plurality of types of electromagnetic induction coils corresponding to the voltage system of the commercial power supply at the manufacturing stage of the fixing device because these electromagnetic induction coils have different shapes and characteristics.

  Accordingly, an object of the present invention is to fix a fixing member that can heat a fixing member at the same level without impairing heat conversion efficiency and without making a separate electromagnetic induction coil even when the voltage of a commercial power source is switched. To provide an apparatus.

  Another object of the present invention is to provide an image forming apparatus provided with such a fixing device.

  As an electromagnetic induction heating type fixing device, as shown in Patent Document 1 (Japanese Patent Laid-Open No. 9-80951), the resonance frequency is reduced from the audible region by connecting the coils in parallel to the noise of the coils. As shown in Patent Document 2 (Japanese Patent Laid-Open No. 9-106207), there has been proposed one that uses a plurality of coils to make the heat distribution of the heating element uniform. However, the fixing devices described in these documents do not correspond to the case where the voltage system of the commercial power source is switched.

In order to solve the above problems, the fixing device of the present invention is:
A fixing member and a pressure member pressed against each other to form a nip through which the sheet passes;
An electromagnetic induction coil for directly or indirectly heating the fixing member by electromagnetic induction;
An inverter circuit interposed between a power source and the electromagnetic induction coil and supplying an alternating current to the electromagnetic induction coil based on a control signal;
The electromagnetic induction coil includes a plurality of partial coils, and each of the partial coils has a connection terminal that is switched and connected in series or in parallel.

  Note that “directly heating by electromagnetic induction” means that the fixing member is directly subjected to electromagnetic induction by the electromagnetic induction coil and heated by eddy current. “Indirect heating” by electromagnetic induction refers to the case where the fixing member is indirectly heated via another heat generating member that receives electromagnetic induction by the electromagnetic induction coil and generates heat by eddy current.

  In the fixing device of the present invention, the inductive reactance of the entire electromagnetic induction coil can be set to a small value by connecting the partial coils in parallel with each other via the connection terminals. On the other hand, the inductive reactance of the entire electromagnetic induction coil can be set to a large value by connecting the partial coils to each other in parallel via the connection terminals. Therefore, even when the voltage of the commercial power supply is switched between, for example, the 100V system and the 200V system, by switching and setting the induction reactance as the entire electromagnetic induction coil according to the voltage of the commercial power supply, Electric power can be supplied to the electromagnetic induction coil while maintaining the level of the alternating current substantially the same by the inverter circuit. Therefore, the fixing member can be heated at the same level without impairing the power-heat conversion efficiency. As a result, stable fixing can be performed.

  It is desirable that each of the partial coils has the connection terminal at both ends of a conducting wire forming the coil. In this case, it becomes easy to connect the partial coils by switching them in series or in parallel.

  In the fixing device according to an embodiment, the plurality of partial coils have the same configuration.

  In the fixing device according to this embodiment, since the plurality of partial coils have the same configuration, it is sufficient to prepare the same partial coil at the stage of manufacturing the fixing device, and a plurality of types of coils corresponding to the voltage of the commercial power source are sufficient. There is no need to prepare. Therefore, the fixing device can be easily manufactured.

  For example, when the number of the partial coils is two and the mutual induction between the partial coils is ignored, when the induction reactance of one partial coil is L, the electromagnetic induction when the partial coils are connected in parallel The induction reactance of the entire coil is L / 2, and the induction reactance of the entire electromagnetic induction coil when the partial coils are connected in series is 2L. That is, the inductive reactance when connected in series is four times that of the inductive reactance when connected in parallel. Therefore, when the voltage of the commercial power source is switched between the 100V system and the 200V system, for example, power can be supplied to the electromagnetic induction coil while maintaining the level of the alternating current substantially the same by the inverter circuit.

  In the fixing device according to an embodiment, the conducting wires forming the plurality of partial coils are wound in parallel with each other.

  In the fixing device of this embodiment, since the conducting wires forming the plurality of partial coils are wound in parallel with each other, the characteristics of the plurality of partial coils are the same. Further, such a plurality of partial coils are manufactured at the same time and can be handled as a single unit after the manufacturing. Therefore, the fixing device can be easily manufactured.

  In the fixing device of one embodiment, an insulator is interposed between the conducting wires forming the plurality of partial coils.

  In the fixing device according to this embodiment, since the insulator is interposed between the conducting wires forming the plurality of partial coils, the conducting wires forming the plurality of partial coils are prevented from being short-circuited. Such an insulator can be wound at the same time as the conducting wires forming the plurality of partial coils at the stage of producing the electromagnetic induction coil. Therefore, the manufacturing labor is not increased much.

In the fixing device of one embodiment,
Each of the partial coils has the connection terminals at both ends of a conducting wire forming the coil,
The connection terminals provided at both ends of each of the partial coils protrude in the same direction from the winding portion of the conducting wire forming the coil, and the dimensions protruding from the winding portion between the connection terminals are different. It is characterized by.

  In the fixing device according to this embodiment, the connection terminals provided at both ends of each of the partial coils protrude in the same direction from the winding portion of the conducting wire forming the coil. It becomes easy to switch and connect in parallel. Since the dimension which protrudes from the said winding part differs between those connection terminals, incorrect connection is prevented.

In one embodiment, the fixing device includes:
A temperature detector for detecting the temperature of the fixing member;
And a power control unit that applies the control signal to the inverter circuit so that the temperature of the fixing member becomes a target temperature based on a detection signal from the temperature detection unit.

  In the fixing device according to the embodiment, the temperature detection unit detects the temperature of the fixing member. The power control unit gives a control signal to control the inverter circuit based on the detection signal from the temperature detection unit so that the temperature of the fixing member becomes the target temperature. As a result, the temperature of the fixing member is controlled with high accuracy so as to become the target temperature.

  The image forming apparatus of the present invention is an image forming apparatus comprising an image forming unit for attaching toner to a sheet and the fixing device of the present invention.

  In the image forming apparatus of the present invention, the image forming unit attaches toner to the sheet, and the fixing device of the present invention fixes the toner to the sheet. As described above, even when the voltage of the commercial power source is switched, the fixing device can stably perform fixing. As a result, the image quality can be improved in the image forming apparatus.

  Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

  FIG. 1 shows a mechanism portion of a fixing device according to an embodiment of the present invention. The mechanism portion of the fixing device includes a fixing roller 1 as a fixing member, a pressure roller 2 as a pressure member, an electromagnetic induction coil 3, and a temperature detection sensor 4 as a temperature detection unit. These parts 1, 2, 3, 4 are positioned and attached to a frame (not shown) as a main body of the fixing device.

  The fixing roller 1 and the pressure roller 2 are pressed against each other by a biasing means such as a spring (not shown) so as to form a nip 5 through which a sheet 6 such as paper passes.

  The fixing roller 1 is rotated in the direction of the arrow a (counterclockwise in FIG. 1) by a driving source (such as a motor) (not shown) in a state where the parts 1, 2, 3, and 4 are attached to the frame, and is driven accordingly. Thus, the pressure roller 2 is rotated in the direction of arrow b (clockwise in FIG. 1). During the fixing operation, the sheet 6 having the toner 9 attached to one side 6a is conveyed from below to above through the nip 5 in FIG. As a result, the toner 9 is fixed to the sheet 6.

  The fixing roller 1 includes, for example, a 5 mm thick Si (silicon) sponge rubber layer, a 50 μm thick alloy layer made of Ni (nickel) and Cr (chromium), and a thickness on an iron core. A Si rubber layer having a thickness of 1 mm and a surface layer made of PFA (copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether) having a thickness of 20 μm are provided. Further, the pressure roller 2 is configured by providing a Si foam rubber layer having a thickness of 5 mm and a PFA surface layer having a thickness of 30 μm on an iron cored bar.

  The electromagnetic induction coil 3 is disposed along the outer peripheral surface of the fixing roller 1 and directly heats the NiCr alloy layer included in the fixing roller 1 by electromagnetic induction. As will be described in detail later, the electromagnetic induction coil 3 is composed of a conducting wire wound a plurality of times so as to form a layer, and the layer is supported by a ferrite core and a holder (not shown). In this example, the electromagnetic induction coil 3 is curved and disposed along the outer peripheral surface of the fixing roller 1. As a result, the magnetic flux generated by the electromagnetic induction coil 3 passes through a magnetic circuit formed by the ferrite core and the NiCr alloy layer of the fixing roller 1.

  The temperature detection sensor 4 is disposed to face the outer peripheral surface of the fixing roller 1 and detects the surface temperature of the fixing roller 1 by a known infrared method.

  FIG. 2 shows a block configuration of a control system for controlling the mechanism portion of FIG. In FIG. 2, the pressure roller 2 is not shown for simplicity.

  As shown in FIG. 2, an inverter circuit 11 is interposed between the commercial power supply 12 and the electromagnetic induction coil 3. The inverter circuit 11 converts commercial power input from the commercial power supply 12 through the commercial power supply path 13 into high frequency alternating power, and outputs the obtained high frequency power to the electromagnetic induction coil 3 through the high frequency power supply path 14. . Thereby, an alternating current is supplied to the electromagnetic induction coil 3, and the electromagnetic induction coil 3 is excited.

  A fixing control circuit 21 as a power control unit gives a control signal including a power instruction value to the inverter circuit 11 based on a detection signal from the temperature detection sensor 4. The power instruction value represents a power value that the inverter circuit 11 should output. Thus, a loop of the fixing roller 1, the temperature detection sensor 4, the fixing control circuit 21, the inverter circuit 11, and the fixing roller 1 is configured, and feedback control is performed so that the surface temperature of the fixing roller 1 becomes the target temperature. The fixing control circuit 21 as described above is configured by, for example, a CPU (Central Processing Unit). The fixing control circuit 21 may be a circuit that controls only the fixing device, or may be a part of a circuit that controls the entire higher-level apparatus, for example, the entire image forming apparatus.

  As shown in FIG. 3, the electromagnetic induction coil 3 includes two partial coils 31 and 32 having the same configuration in the same layer.

  The partial coil 31 is formed by winding a conducting wire indicated by a single solid line in the figure into an oval shape a plurality of times. The partial coil 31 includes an outward path portion 31a and a return path portion 31b extending along the longitudinal direction of the fixing roller 1 (indicated by an arrow d in the drawing), and an outward path portion 31a and a return path portion 31b at both ends of the fixing roller 1. And curved portions 31c and 31d connecting the two. Further, connection terminals T1 and T2 are provided at both ends of the partial coil 31 in such a manner as to protrude in the same direction (leftward downward in the drawing) from the winding portion of the conducting wire forming this coil.

  Similarly, the partial coil 32 is formed by winding a conducting wire indicated by a single solid line in the figure into an oval shape a plurality of times. The partial coil 32 includes a forward path portion 32a and a backward path portion 32b extending along the longitudinal direction d of the fixing roller 1, and curved portions 32c and 32d that connect the forward path portion 32a and the backward path portion 32b at both ends of the fixing roller 1. Have Further, at both ends of the partial coil 32, connection terminals T3 and T4 are provided in such a manner as to protrude in the same direction (leftward downward in the figure) from the winding portion of the conducting wire forming the coil.

  The connection terminals T1 and T2 of the partial coil 31 and the connection terminals T3 and T4 of the partial coil 32 are provided in order to easily connect the partial coils 31 and 32 by switching them in series or in parallel. For this reason, the connection terminals T1, T2 and the connection terminals T3, T4 are all protruded in the same direction. In this example, each of the connection terminals T1, T2; T3, T4 protrudes from the winding portion of the conducting wire by the same dimension.

  It should be noted that the conductors forming each of the partial coils 31 and 32 are actually hundreds of strands (copper wires having a diameter of about 0.18 mm to 0.20 mm and insulated with enamel) in order to increase the energization efficiency. It is a known stranded wire having a diameter of about several mm formed by bundling about ten wires. Thereby, the drive frequency of 10 kHz to 100 kHz and the power of 100 W to 2000 W can be received from the high frequency inverter 4.

As the voltage (nominal value) of the commercial power source 12, two types of 100V system and 200V system are used depending on the region where the fixing device and the image forming apparatus including the same are used. When the voltage is V, the inductive reactance of the electromagnetic induction coil 3 is L, and the angular velocity of the alternating current is ω (= 2πf; f is a frequency), the power P supplied to the electromagnetic induction coil 3 is
P = V × V / ωL (1)
It is expressed. As can be seen from this equation (1), in order to supply the same power to the electromagnetic induction coil 3 while maintaining the frequency f of the alternating current by the inverter circuit 11 substantially the same in the 100V system and the 200V system, 100V Compared to the inductive reactance at the time of use, the inductive reactance at the time of using 200 V needs to be four times.

  Here, in the fixing device of this embodiment, the partial coils 31, 32 included in the electromagnetic induction coil 3 have connection terminals T1, T2; T3, T4. Therefore, the induction reactance of the electromagnetic induction coil 3 as a whole can be switched and set by switching and connecting the partial coils 31 and 32 in parallel or in series according to the voltage of the commercial power supply.

  In order to connect the partial coils 31 and 32 in parallel, for example, the connection terminal T2 on the winding end side of the partial coil 31 and the connection terminal T3 on the left side of the partial coil 32 are short-circuited and the connection on the left side of the partial coil 31 is connected. The terminal T1 and the connection terminal T4 on the end of the 32 turns of the partial coil are short-circuited. The short-circuited connection terminals T2 and T3 and the short-circuited connection terminals T1 and T4 are connected to the inverter circuit 11.

  In order to connect the partial coils 31 and 32 in series, for example, the connection terminal T2 on the winding end side of the partial coil 31 and the connection terminal T3 on the left side of the partial coil 32 are short-circuited, and the connection terminal on the left side of the partial coil 31 is connected. T1 and a connection terminal T4 on the end of 32 turns of the partial coil are connected to the inverter circuit 11.

  When the mutual induction between the partial coils 31 and 32 is ignored, assuming that the induction reactance of one partial coil is L, the induction reactance of the electromagnetic induction coil 3 as a whole when the partial coils 31 and 32 are connected in parallel is L. The induction reactance of the electromagnetic induction coil 3 as a whole when the partial coils 31 and 32 are connected in series is 2L. That is, the inductive reactance when connected in series is four times that of the inductive reactance when connected in parallel. Therefore, based on the formula (1), when the voltage of the commercial power supply 12 is a 100V system, the partial coils 31 and 32 are used in parallel connection, and when the voltage of the commercial power supply 12 is a 200V system, The coils 31 and 32 are used in a state where they are connected in series. As a result, when the voltage of the commercial power supply 12 is switched between, for example, the 100V system and the 200V system, the inverter circuit 11 supplies power to the electromagnetic induction coil 3 while maintaining the alternating current level substantially the same. it can. Therefore, stable fixing can be performed.

  Further, since the partial coils 31 and 32 have the same configuration, it is sufficient to prepare the same partial coil at the manufacturing stage of the fixing device, and it is not necessary to prepare a plurality of types of coils corresponding to the voltage of the commercial power source 12. Therefore, the fixing device can be easily manufactured.

  As shown in FIG. 4, you may wind the conducting wire which comprises the partial coils 31 and 32 in parallel mutually. In this case, the characteristics of the plurality of partial coils 31 and 32 are the same. Further, such a plurality of partial coils 31 and 32 are manufactured simultaneously. Further, after the production, the electromagnetic induction coil 3 can be handled as a unit. Therefore, the fixing device can be easily manufactured.

  Moreover, you may insert an insulator, for example, heat resistant resin, between the conducting wires which comprise the partial coils 31 and 32. FIG. In such a case, it is possible to prevent the conducting wires forming the partial coils 31 and 32 from being short-circuited by the voltage generated in the coil. Such an insulator can be wound at the same time as the conducting wires forming the partial coils 31 and 32 at the stage of producing the electromagnetic induction coil 3. Therefore, the manufacturing labor is not increased much.

  FIG. 5 shows a further modification of the partial coil included in the electromagnetic induction coil 3. The electromagnetic induction coil 3 includes two partial coils 35 and 36 having the same configuration in the form of the same layer. In addition, 35a, 36a is an outward part, 35b, 36b is a return part, 35c, 35d, 36c, 36d is a curved part. In this example, the connection terminals T1 and T2 provided at both ends of the partial coil 35 protrude in the same direction (downward in the drawing in the figure) from the winding portion of the conducting wire forming the coil, and the left side connection terminal T1 The protruding dimension is long and the protruding dimension of the right connection terminal T2 is short. Similarly, the connection terminals T3 and T4 provided at both ends of the partial coil 36 protrude in the same direction (downward in the drawing in the drawing) from the winding portion of the conducting wire forming the coil, and the left connection terminal T3 protrudes. The dimension is long and the protruding dimension of the right connection terminal T4 is short. Thus, when the dimension which protrudes from the winding part differs between the connection terminals provided in the both ends of each partial coil, in each partial coil 35 and 36, connection terminal T1, T3 of one side is provided. And the connection terminals T2 and T4 on the other side can be easily distinguished. Therefore, erroneous connection can be prevented.

  FIG. 6 shows a similar modification of the partial coil included in the electromagnetic induction coil 3. The electromagnetic induction coil 3 includes two partial coils 37 and 38 having the same configuration as each other in a form that is symmetrical and forms the same layer. In addition, 37a and 38a are an outward part, 37b and 38b are a return part, 37c, 37d, 38c, and 38d are curved parts. In this example, the connection terminals T1 and T2 provided at both ends of the partial coil 37 protrude in the same direction (downward in the drawing in the drawing) from the winding portion of the conducting wire forming the coil, and the left side connection terminal T1 The protruding dimension is long and the protruding dimension of the right connection terminal T2 is short. On the other hand, the connection terminals T3 and T4 provided at both ends of the partial coil 38 protrude in the same direction (downward in the drawing in the drawing) from the winding portion of the conducting wire forming the coil, and the protruding dimension of the left connection terminal T3. Is short, and the protruding dimension of the right connection terminal T4 is long. Also in this case, similarly to the example of FIG. 5, in each of the partial coils 37 and 38, the connection terminals T1 and T3 on one side can be easily distinguished from the connection terminals T2 and T4 on the other side. Therefore, erroneous connection can be prevented.

  From the viewpoint of preventing erroneous connection, voltage system detection for detecting whether the voltage of the commercial power supply 12 is 100 V or 200 V in the inverter circuit 11 or between the inverter circuit 11 and the electromagnetic induction coil 3. And a changeover switch unit that switches and connects two partial coils (for example, the partial coils 31 and 32 in FIG. 1) in parallel or in series according to the detection result of the voltage system detection unit. good. In such a case, the induction reactance of the electromagnetic induction coil 3 can be automatically switched according to the voltage of the commercial power supply 12. Therefore, erroneous connection can be prevented.

  FIG. 7 shows another mechanism part replacing the mechanism part shown in FIG. This mechanism portion is different from the mechanism portion of FIG. 1 in that an electromagnetic induction coil (indicated by reference numeral 3I) is provided inside the fixing roller 1. In addition, the same code | symbol is attached | subjected to the same component as the component in FIG. 1, and description is abbreviate | omitted.

  As shown in FIG. 8, the electromagnetic induction coil 3 </ b> I is wound around cores 73 and 74 having the same configuration extending elongated in the longitudinal direction of the fixing roller 1 (indicated by an arrow d in the drawing). Partial coils 71 and 72 having a configuration are included. At both ends of the partial coil 71, connection terminals T <b> 1 and T <b> 2 are provided in such a manner as to protrude in the same direction (leftward downward in the figure) from the winding portion of the conducting wire forming this coil. Similarly, connection terminals T3 and T4 are provided at both ends of the partial coil 32 in such a manner as to protrude in the same direction (downward left in the figure) from the winding portion of the conducting wire forming the coil.

  Even in this configuration, the inductive reactance of the electromagnetic induction coil 3I as a whole can be switched and set by switching the partial coils 71 and 72 in parallel and in series in accordance with the voltage of the commercial power supply. As a result, when the voltage of the commercial power supply 12 is switched between, for example, a 100V system and a 200V system, the inverter circuit 11 supplies power to the electromagnetic induction coil 3I while maintaining the alternating current level substantially the same. it can. As a result, stable fixing can be performed.

  Further, since the partial coils 71 and 72 have the same configuration, it is sufficient to prepare the same partial coil at the manufacturing stage of the fixing device, and it is not necessary to prepare a plurality of types of coils corresponding to the voltage of the commercial power source 12. Therefore, the fixing device can be easily manufactured.

  Although the case where the number of partial coils included in the electromagnetic induction coil is two has been described above, naturally, a larger number of partial coils may be provided.

  The fixing device of the present invention is suitably used as a component of an image forming apparatus that attaches toner to a sheet by an electrophotographic process. That is, the image forming unit provided in the image forming apparatus attaches toner to the sheet by an electrophotographic process, and the fixing device of the present invention fixes the toner to the sheet. As described above, even when the voltage of the commercial power source is switched, the fixing device can stably perform fixing. As a result, the image quality can be improved in the image forming apparatus.

It is a figure which shows the structure of the mechanism part of the fixing device of one Embodiment of this invention. It is a figure which shows the block configuration of the control system for controlling the mechanism part of FIG. It is a figure which shows two partial coils which make the electromagnetic induction coil in FIG. It is a figure which shows the structure which carried out the mutually parallel winding of the conducting wire which makes the said two partial coils. It is a figure which shows the modification of the said two partial coils. It is a figure which shows another modification of the said two partial coils. It is a figure which shows another mechanism part replaced with the mechanism part of FIG. It is a figure which shows the two partial coils which make the electromagnetic induction coil in FIG.

Explanation of symbols

1 fixing roller 3, 3I electromagnetic induction coil 31, 32, 35, 36, 37, 38, 71, 72 partial coil T1, T2, T3, T4 connection terminal

Claims (7)

A fixing member and a pressure member pressed against each other to form a nip through which the sheet passes;
An electromagnetic induction coil for directly or indirectly heating the fixing member by electromagnetic induction;
An inverter circuit interposed between a power source and the electromagnetic induction coil and supplying an alternating current to the electromagnetic induction coil based on a control signal;
The electromagnetic induction coil includes a plurality of partial coils, and each of the partial coils has a connection terminal that is switched and connected in series or in parallel. The fixing device according to claim 1,
The fixing device according to claim 1, wherein the plurality of partial coils have the same configuration. The fixing device according to claim 1,
The fixing device, wherein the conducting wires forming the plurality of partial coils are wound in parallel with each other. The fixing device according to claim 1,
A fixing device, wherein an insulator is interposed between the conducting wires forming the plurality of partial coils. The fixing device according to claim 1,
Each of the partial coils has the connection terminals at both ends of the conducting wire forming the coil,
The connection terminals provided at both ends of each of the partial coils protrude in the same direction from the winding part of the conducting wire forming the coil, and the dimensions protruding from the winding part differ between the connection terminals. A fixing device. The fixing device according to claim 1,
A temperature detector for detecting the temperature of the fixing member;
A fixing device comprising: a power control unit that applies the control signal to the inverter circuit so that the temperature of the fixing member becomes a target temperature based on a detection signal from the temperature detection unit. An image forming unit for attaching toner to the sheet;
An image forming apparatus comprising the fixing device according to claim 1.

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