KR102169513B1 - Induction heating type fusing device and image forming apparatus using the same - Google Patents

Abstract

The disclosed fixing device includes a rotatable heating element and a coil unit circuit that generates a magnetic flux for heating the heating element. The coil unit circuit includes a coil unit disposed to be spaced apart from the outer peripheral surface of the heating element in an opposite direction, and a power supply unit supplying electric power to the coil unit. The coil unit includes a first coil disposed along the width direction of the heating element, a pair of second coils disposed to overlap in opposite directions at both ends of the first coil in the width direction, and a direction opposite to the central part in the width direction of the first coil. And a third coil disposed to overlap. The coil unit circuit includes a switching connection portion for switching the series connection type of the first coil, the second coil, and the third coil so that the current directions of the first coil, the second coil, and the third coil are switched.

Description

Induction heating type fusing device and image forming apparatus using the same.

A fixing device and an image forming device employing an induction heating method are disclosed.

As a fixing device for an image forming apparatus, for example, the induction heating fixing device described in Patent Document 1 is known.

(Patent Document 1) US 2013-0078019 A

The induction heating fixing device described in Patent Document 1 includes a first coil capable of heating a heating element to a maximum paper width that can be fed, and a second coil disposed to overlap the first coil at both ends of the first coil in the width direction. In addition, the induction heating fixing device includes a power supply unit for supplying electric power to the first coil and the second coil, and a switch for controlling the direction of current flowing through the first coil and the second coil to be the same or opposite.

When passing a wide paper (paper overlapping the second coil) through the above-described fixing device, currents in the same direction are supplied to the first coil and the second coil. When passing a paper having a narrow width (paper not overlapping with the second coil), currents in opposite directions are supplied to the first coil and the second coil. Thereby, when passing a paper having a narrow width, it is possible to suppress the generation of magnetic flux in a portion of the heat generating element through which the paper does not pass (non-feeding portion), and suppress an increase in temperature of the non-feeding portion.

If the temperature distribution of the heating element of the fixing device is non-uniform, there is a fear of affecting the image. For example, if the temperature distribution of the heating element is non-uniform, the glossiness of the printed image may be non-uniform. In addition, when the temperature of a partial region of the heating element is higher than the temperature required for fixing, unnecessary energy (power) is consumed in the induction heating fixing device.

An object of the present invention is to provide an induction heating fixing device and an image forming device that can achieve uniform temperature distribution of a heating element.

A fixing device according to an aspect includes: a rotatable heating element; And a coil unit circuit that generates magnetic flux for heating the heating element, and includes a coil unit disposed to be spaced apart from an outer circumferential surface of the heating element in an opposite direction and a power supply unit supplying power to the coil unit; and

The coil unit may include: a first coil disposed along a width direction of the heating element; A pair of second coils disposed to overlap in the opposite direction on both ends of the first coil in the width direction; And a third coil disposed to overlap in the opposite direction at a central portion in the width direction of the first coil,

The coil unit circuit includes a switching connection part for switching a series connection type of the first coil, the second coil, and the third coil so that the current direction of the first coil, the second coil, and the third coil is switched. Equipped.

The number of turns of the second coil may be less than the number of turns of the first coil.

In the rotational direction of the heating element, an inner width of the second coil and the third coil may be greater than an inner width of the first coil, and an outer width of the second coil and the third coil may be smaller than an outer width of the first coil. .

The second coil and the third coil may have the same separation distance from the heating element in the opposite direction and the number of turns.

The second coil and the third coil have a structure in which ends in the width direction are disposed adjacent to each other, ends in the width direction are disposed to be spaced apart from each other, and a separation distance from the heating element in the opposite direction is It may be arranged in any one of the structures that are different and are arranged so that the ends in the width direction overlap in the opposite direction.

The fixing device may further include a core portion including a plurality of cores as concentrating magnetic flux generated by the first coil, the second coil, and the third coil on the heating element, and the core The part may be disposed at a position overlapping at least with the second coil and the third coil in the width direction.

The first coil may be disposed closer to the core portion than the second coil and the third coil in the opposite direction.

The core portion may include a connection portion overlapping a connection region extending from the second coil-side end of the third coil to the third coil-side end of the second coil in the opposite direction; And a main part overlapping the coil part in addition to the connection part, wherein the connection part and the main part have a structure having different arrangement densities of the plurality of cores and the same magnetic permeability, and different magnetic permeability of the plurality of cores. A structure and a structure in which distances in the opposite direction from the heating element of the plurality of cores are different from each other may have a structure.

A ratio of the magnetic flux generated by the second coil and the third coil to the magnetic flux generated by the first coil may be 50% or less.

The coil unit may include a pair of fourth coils disposed to overlap in the opposite direction with both ends of the first coil and the second coil in the width direction; And a fifth coil disposed to overlap the center portion in the width direction of the first coil and the third coil in the opposite direction, and wherein the length of the width direction of the fourth coil and the fifth coil The ratio is different from the ratio of the length in the width direction of the second coil and the third coil, and the switching connection part comprises the first coil, the second coil, the third coil, the fourth coil, and the fifth coil. When connected in series, the first coil, the second coil, and the third coil so that the current directions of the first coil, the second coil, the third coil, the fourth coil, and the fifth coil are switched. , It is possible to switch the series connection type of the fourth coil and the fifth coil.

The ratio of the magnetic flux generated by the fourth coil and the fifth coil to the magnetic flux generated by the first coil may be 50% or less.

The coil unit circuit may further include a control unit for controlling at least one of the power supply unit and the switching connection unit, wherein the control unit is configured to prepare for feeding, start feeding, continuous feeding, and end feeding, the power At least one of the supply unit and the switching connection unit can be individually set.

The control pattern may include a pattern for setting supply and stop of power by the power supply unit.

The control pattern may include a pattern for setting a series connection type of the coil unit by the switching connection unit.

The control unit may have a plurality of the control patterns.

The control unit may determine the control pattern according to at least one of a width of the recording medium, a thickness of the recording medium, and a difference between a measured temperature of the heating element and a target temperature.

The fixing device may include: a first temperature detection sensor configured to detect a temperature of a region of the heating element that overlaps a central portion of the first coil and the third coil in the width direction and the opposite direction; And a pair of second temperature detection sensors configured to detect a temperature of a region where the first coil and the second coil overlap each other in the opposite direction and a region overlapped in the opposite direction, among the regions of the heating element. can do.

The coil unit may include a pair of fourth coils disposed to overlap in the opposite direction with both ends of the first coil and the second coil in the width direction; A fifth coil disposed to overlap the central portion of the first coil and the third coil in the width direction and the opposite direction; may be further provided. The fifth coil may be disposed to overlap an end portion of the second coil on the third coil side in the opposite direction. The fixing device further includes a pair of third temperature detection sensors for detecting a temperature of a region where the second coil and the fifth coil overlap each other and a region overlapping each other in the opposite direction of the region of the heating element; , The first temperature detection sensor detects a temperature of a region overlapping the central portion in the width direction of the first coil, the third coil, and the fifth coil in the opposite direction among the regions of the heating element, and the first 2 The temperature detection sensor may detect a temperature of a region where the first coil, the second coil, and the fifth coil overlap each other and a region overlapping in the opposite direction among the regions of the heating element.

When feeding a first recording medium, a second recording medium wider than the first recording medium, and a third recording medium wider than the second recording medium, the length in the width direction of the first coil is the Is greater than the width of the third recording medium, the length in the width direction of the third coil is smaller than the width of the second recording medium and greater than the width of the first recording medium, and the length in the width direction of the fifth coil is It may be smaller than the width of the third recording medium and larger than the width of the second recording medium.

An image forming apparatus according to an aspect includes the above-described fixing apparatus.

According to the above-described embodiments, it is possible to provide an induction heating fixing device and an image forming device that can achieve uniform temperature distribution of a heating element.

1 is a schematic configuration diagram of an image forming apparatus according to a first embodiment.
2 is a schematic diagram showing a fixing device of the image forming apparatus of FIG. 1.
3 is a perspective view showing the fixing device of FIG. 2.
4 is a plan view of a coil and a core portion according to the fixing device of FIG. 3.
5 is a plan view in which the first coil and the core portion of FIG. 4 are omitted.
Fig. 6 is a coil unit circuit diagram (Fig. 6(a)) and a diagram showing a temperature distribution of a heat generating rotor (Fig. 6(b)) in a first series connection type.
Fig. 7 is a coil unit circuit diagram (Fig. 7(a)) and a diagram showing a temperature distribution of a heat generating rotor (Fig. 7(b)) in a second series connection type.
8 is a diagram illustrating a coil unit circuit diagram and a temperature distribution of a heating rotor according to a comparative example.
9 is a view comparing the temperature distribution of the heating rotor according to the first embodiment and the temperature distribution of the heating rotor according to the comparative example.
10 is a diagram showing a coil configuration and a temperature distribution of a heating element of the fixing device according to the second embodiment.
FIG. 11 shows that when paper with a width wide enough to contact the portion facing the fourth coil of the heating rotor is fed (Fig. 11(a)), it does not contact the portion facing the fourth coil of the heating rotor, 2 When paper that is wide enough to contact the part opposite to the coil is fed (Fig. 11(b)), when paper that does not reach the part opposite to the second coil of the heating rotor is fed (Fig. 11(c) )) of the coil unit.
Fig. 12 shows a current flowing through the coil in the connection area of the third embodiment (Fig. 12(a)), the current flowing through the coil in the connection area of the fourth embodiment (Fig. 12(b)), and the fifth embodiment It is a diagram showing a state (Fig. 12(c)) of a current flowing through the coil in the connection area of the shape.
Fig. 13 is a diagram showing a magnetic flux distribution of the heat generating rotor in the third embodiment (Fig. 13(a)) and a magnetic flux distribution of the heat generating rotor in the fourth embodiment (Fig. 13(b)).
14 is a perspective view showing a fixing device according to a third embodiment.
15 is a plan view of a coil and a core according to the fixing device of FIG. 14.
16 is a perspective view showing a fixing device according to a modified example.
17 is a diagram showing a magnetic flux distribution of a heat generating rotating body in a fifth embodiment.
Fig. 18 is a perspective view (Fig. 18(a)) showing a fixing device according to a modification, and a plan view of a coil and a core (Fig. 18(b)).
19 is a diagram showing a current flowing through a coil in the fixing device according to the sixth embodiment.
FIG. 20 is a diagram illustrating a temperature distribution of a heating rotor when a current is passed through it as shown in FIG. 19.
21 is a diagram showing a control pattern.
22 is a table showing the relationship between various conditions and the control pattern in FIG. 21.
23 is a diagram showing a control pattern of a fixing device according to a seventh embodiment.
24 is a diagram illustrating a control pattern of a fixing device according to a seventh embodiment.
25 is a table showing the relationship between various conditions and the control patterns in FIGS. 23 and 24.
26 is a schematic diagram showing a temperature detection sensor of a fixing device according to an eighth embodiment.
Fig. 27 is a diagram showing a temperature distribution of a heating element for each paper size.
28 is a schematic diagram showing a temperature detection sensor of a fixing device according to a ninth embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, in each drawing, the same reference numerals are assigned to the same or corresponding parts, and redundant explanations are omitted.

[First embodiment]

(Overall configuration of image forming device)

As shown in Fig. 1, the image forming apparatus 1 includes a transfer unit 10, a transfer unit 20, a photosensitive drum 30, four developing units 100, and a fixing device 40. I can. The image forming apparatus 1 is, for example, an image forming apparatus using an electrophotography technique.

The transfer unit 10 finally accommodates the paper P (media) as a recording medium on which an image is formed, and at the same time transfers the paper P onto the recording medium transfer path. The paper P is stacked and accommodated in the cassette C. The transfer unit 10 causes the paper P to reach the secondary transfer area R in accordance with the timing at which the toner image to be transferred onto the paper P reaches the secondary transfer area R.

The transfer unit 20 conveys the toner images formed by the four developing units 100 to the secondary transfer area R for secondary transfer to the paper P. The transfer unit 20 may include a transfer belt 21, suspension rollers 21a, 21b, 21c, 21d, a primary transfer roller 22 and a secondary transfer roller 24. The suspension rollers 21a, 21b, 21c, and 21d suspend the transfer belt 21. The primary transfer roller 22 has a transfer belt 21 interposed between it and the photoreceptor drum 30. The secondary transfer roller 24 has a transfer belt 21 interposed between it and the suspension roller 21d.

The transfer belt 21 is an endless belt that is circulated and moved by suspension rollers 21a, 21b, 21c, and 21d. The primary transfer roller 22 is installed to press the photoreceptor drum 30 from the inner circumferential side of the transfer belt 21. On the other hand, the secondary transfer roller 24 is installed so as to press the suspension roller 21d from the outer peripheral side of the transfer belt 21. Further, the transfer unit 20 may further include a belt cleaning device or the like for removing toner adhering to the transfer belt 21.

The photoconductor drum 30 is a drum-shaped latent electrostatic image bearing member in which an image is formed on an outer circumferential surface, and may include, for example, an OPC (Organic 　 Photo Conductor). The image forming apparatus 1 according to the present embodiment is an image forming apparatus capable of forming a color image. In the image forming apparatus 1, four photoreceptor drums 30 are provided along the moving direction of the transfer belt 21 corresponding to each color of magenta, yellow, cyan, and black, for example. Each photoreceptor drum 30 is operated by a drum motor 35. A charging roller 32, an exposure unit 34, a drum motor 35, a cleaning unit 38, and a developing unit 100 are installed along the outer periphery of each photosensitive drum 30, respectively.

A charging voltage is applied to the charging roller 32, whereby the surface of the photosensitive drum 30 is uniformly charged to a predetermined potential. The charging roller 32 is installed to be close to or in contact with the photoreceptor drum 30, and performs the above-described uniform charging by using a small gap (GAP) discharge. The exposure unit 34 exposes the surface of the photoreceptor drum 30 charged by the charging roller 32 according to image information to be formed on the paper P. Accordingly, a potential of a portion of the surface of the photoreceptor drum 30 exposed by the exposure unit 34 is changed to form an electrostatic latent image. The four developing units 100 develop electrostatic latent images as the developing voltage is applied. In more detail, each developing unit 100 generates a toner image by developing an electrostatic latent image drawn on the photoreceptor drum 30 using the toner supplied from the toner tank 36. Each of the four toner tanks 36 is filled with magenta, yellow, cyan, and black toners.

The cleaning unit 38 recovers toner (remaining toner) remaining on the photoreceptor drum 30 even after being temporarily transferred to the transfer belt 21. The cleaning unit 38 may include, for example, a cleaning braid, and removes residual toner by bringing the cleaning braid into contact with the outer peripheral surface of the photosensitive drum 30. In addition, the cleaning unit 38 may include an antistatic lamp 39 positioned close to the outer periphery of the photoreceptor drum 30 to control the surface potential of the photoreceptor drum 30. The antistatic lamp 39 is an erase lamp that discharges the surface of the photoconductor drum 30 by lighting. The antistatic lamp 39 is operated during image formation (when printing) to set the surface potential of the photosensitive drum 30 to a desired value. Further, the anti-static lamp 39 is operated when a non-image is formed, such as after transfer, to reset the surface potential by making the residual charge of the photoreceptor drum 30 less than or equal to the light attenuation voltage of the photoreceptor drum 30. The antistatic lamp 39 eliminates the instability of the charging potential due to the residual charge and suppresses the occurrence of ghosts in the image. In the case of non-image formation, not only before/after the operation of printing, but also between pages when image formation is performed over multiple pages is included.

The fixing device 40 may include a pressing rotating body 42 and a heating rotating body 44. The fixing device 40 adheres and fixes the toner image secondaryly transferred from the transfer belt 21 to the paper P to the paper P. Details of the fixing device 40 will be described later.

Further, the image forming apparatus 1 is provided with discharge rollers 52 and 54 for discharging the paper P on which the toner image is fixed by the fixing device 40 to the outside of the apparatus.

Next, the operation of the image forming apparatus 1 will be described. When the image signal of the image to be recorded is input to the image forming apparatus 1, the control unit of the image forming apparatus 1 uniformly charges the surface of the photoreceptor drum 30 to a predetermined electric potential using the charging roller 32. , Using the exposure unit 34, the surface of the photoreceptor drum 30 is irradiated with laser light modulated in response to an image signal to form an electrostatic latent image.

Meanwhile, in the developing unit 100, a developer of a two-component developing method is supported on the developing roller 110. The developer includes a toner and a carrier. The developing unit 100 is sufficiently charged by mixing and stirring the toner and the carrier. When the developer is conveyed to the area opposite to the photoreceptor drum 30 by rotation of the developing roller 110, the toner in the developer is moved to an electrostatic latent image formed on the outer peripheral surface of the photoreceptor drum 30. Accordingly, an electrostatic latent image is developed. The toner image thus formed is first transferred from the photoreceptor drum 30 to the transfer belt 21 in a region where the photoreceptor drum 30 and the transfer belt 21 face each other. On the transfer belt 21, toner images formed on the four photosensitive drums 30 are sequentially stacked to form one stacked toner image. Then, the stacked toner image is secondaryly transferred to the paper P transferred from the transfer unit 10 in the secondary transfer area R where the suspension roller 21d and the secondary transfer roller 24 face each other.

The paper P on which the stacked toner image is secondary transferred is transferred to the fixing device 40. When the paper P is passed between the heat generating rotating body 44 and the pressure rotating body 42 while applying heat and pressure, the laminated toner image is melted and fixed to the paper P. After that, the paper P is discharged to the outside of the image forming apparatus 1 by the discharge rollers 52 and 54. Further, when the transfer unit 20 is provided with a belt cleaning device, the toner remaining on the transfer belt 21 can be removed by the belt cleaning device after the stacked toner image is secondaryly transferred to the paper P.

(Configuration of fixing device)

Next, a detailed configuration of the fixing device 40 will be described with reference to FIG. 2. As shown in FIG. 2, the fixing device 40 is an induction heating fixing device including a pressurizing rotating body 42, a heat generating rotating body 44, and a magnetic field generating device 45. In addition, the magnetic field generating device 45 concentrates the magnetic flux generated by the coil unit 46 and the coil unit 46 disposed opposite to the outer peripheral surface 44a of the heating rotor 44 to the heating rotor 44 It is provided with a core portion 47 to be made.

The pressing rotating body 42 is a cylindrical rotating body installed to press the heating rotating body 44, and may include, for example, a silicone rubber having a hardness of JISA65 degrees. The pressurized rotating body 42 may have a surface coated with a fluorine resin or the like in order to increase wear resistance or releasability. In addition, the pressurized rotating body 42 may include a so-called sponge-type foam. In addition, the pressurized rotating body 42 may include a material having low thermal conductivity to prevent heat diffusion. The length of the pressure rotating body 42 in the axial direction is, for example, 210 to 370 mm, and its outer diameter is, for example, 20 to 100 mm.

The heating rotating body 44 is a cylindrical rotating body (rotatable heating body) having a heating layer, and may have a multilayer structure including a metal conductor made of a magnetic material such as nickel, chromium, or copper. In order to increase wear resistance or releasability, the heating rotor 44 may have a surface coated with a fluororesin or the like. In this case, the multilayered heating rotor 44 may include a heating layer of 10 to 50 μm, a rubber layer of 50 to 500 μm, and a fluororesin layer of 10 to 50 μm. The length of the heating rotor 44 in the axial direction is, for example, 210 to 370 mm, and its outer diameter is, for example, 20 to 100 mm.

The heating rotor 44 generates heat under the influence of the magnetic flux generated in the coil part 46. That is, the magnetic flux generated in the coil part 46 is guided by the core part 47 to the outer peripheral surface 44a of the heating rotor 44. Further, the magnetic flux generates an eddy current, and Joule's Heat is generated on the outer circumferential surface 44a of the heating rotation body 44, so that the heating rotation body 44 generates heat. The heat generating rotor 44 has a surface temperature of, for example, 140 to 200°C during a predetermined fixing operation.

On the inner circumferential side of the heating rotor 44, a nip forming member 44b, which is a cylindrical rotating body, is disposed. The rotation axis of the nip forming member 44b is parallel to the rotation axis of the heating rotor 44. The nip forming member 44b presses the heat generating rotating body 44 from the inner peripheral surface side of the heat generating rotating body 44 to the pressing rotating body 42 side. The heating rotor 44 is rotated in one direction (rotation direction (T1)) by a drive motor (not shown), and the pressurization rotation body 42 is driven thereto and a rotation direction opposite to the rotation direction (T1). It is rotated to (T2). Then, the pressurizing rotating body 42 and the heating rotating body 44 melt and fix the toner image onto the paper by passing the paper through the fixing nip portion N, which is a contact area with each other.

The coil unit 46 is a magnetic flux generating means for generating a magnetic flux by electromagnetic induction when a high-frequency current is applied. The output frequency of the coil unit 46 may be, for example, 20 kHz to 100 kHz. The coil unit 46 may be disposed on the opposite side of the pressing rotation body 42 based on the heating rotation body 44 and may be disposed to cover approximately half of the outer circumference of the heating rotation body 44. The coil part 46 is not in contact with the heating rotor 44 and is disposed in a position close to the outer circumferential surface 44a. The separation distance between the coil part 46 and the heating rotor 44 may be, for example, 1 to 10 mm. The coil part 46 extends between substantially both ends of the heating rotation body 44 in the direction of the rotation axis of the heating rotation body 44 (the width direction of the heating rotation body 44) D1.

The core portion 47 is a magnetic core that is disposed to cover the coil portion 46 and forms a magnetic path of the magnetic flux generated by the coil portion 46. The core portion 47 receives the magnetic flux and guides it to the heating rotor 44 so that the magnetic flux generated from the coil portion 46 does not leak. The core portion 47 is disposed on the opposite side of the heating rotor 44 with respect to the coil portion 46. Although the core part 47 is not in contact with the coil part 46, it is disposed at a close position, and the separation distance from the coil part 46 may be, for example, 1 to 10 mm. In addition, the core portion 47 may be formed of a magnetic material with high permeability and low loss, such as ferrite.

Next, details of the coil unit 46 and the core unit 47 will be described with reference to FIGS. 3 to 5. As shown in Figs. 3 to 5, the coil unit 46 is a race track type (semicircle) coil and extends in the rotation axis direction D1 and the rotation direction T1. The coil part 46 connects a pair of straight parts 46a and 46b extending in the rotational axis direction D1 and arranged parallel to each other in the rotational direction T1 and both ends of the linear parts 46a and 46b, respectively. Thus, a pair of arc portions 46c and 46c extending in the rotational direction T1 are provided. The coil wires of the coil part 46 are parallel to the rotation axis direction D1 and the rotation direction T1 in order to reduce the thickness.

The coil unit 46 includes a first coil 48, a pair of second coils 49, and a third coil 50. The first coil 48 is disposed along the rotation axis direction D1. In the direction of the rotation axis D1, the length of the first coil 48 may be the same as the heating rotation body 44, or may be slightly longer than the heating rotation body 44. The first coil 48 is disposed substantially overlapping with the entire heat generating body 44 in the rotation axis direction D1 in the opposite direction (FIG. 2: D2). The second coil 49 may be shorter than half the length of the heat generating rotor 44 in the rotation axis direction D1. The second coil 49 is disposed to overlap with both ends 48x in the rotation axis direction D1 of the first coil 48 in the opposite direction D2. The third coil 50 is disposed superimposed on the central portion 48y in the rotation axis direction D1 of the first coil 48 in the opposite direction D2. Further, the first coil 48, the second coil 49, and the third coil 50 each have a pair of straight portions 46a and 46b, and a pair of arc portions 46c and 46c, respectively.

The distance from the outer peripheral surface 44a of the heating rotor 44 to the second coil 49 and the third coil 50 is less than the distance from the outer peripheral surface 44a of the heating rotor 44 to the first coil 48 It can be short. That is, the second coil 49 and the third coil 50 may be disposed closer to the heating rotor 44 than the first coil 48.

The second coil 49 and the third coil 50 may have the same distance from the heating rotor 44 in the opposite direction D2. In addition, the third coil 50 is disposed in a region different from the second coil 49 in the rotation axis direction D1 so as to be positioned between the pair of second coils 49 (see FIG. 5). In the rotation axis direction D1 of the second coil 49, the arc portion 46c on the side of the third coil 50 is disposed adjacent to the arc portion 46c of the third coil 50. In this way, the connecting region 46x is formed by the arc portion 46c of the second coil 49 and the arc portion 46c of the third coil 50 disposed adjacent to each other. That is, the connection region 46x is a region from the arc portion 46c, which is the end of the second coil 49 on the side of the third coil 50, to the arc portion 46c, which is the end of the third coil. That is, the connection area 46x includes the arc portion 46c of the second coil 49 and the arc portion 46c of the third coil 50. The length obtained by adding the length of the second coil 49 in the rotation axis direction D1 and the rotation axis direction D1 of the third coil 50 is the length in the rotation axis direction D1 of the first coil 48 Can be almost the same as In addition, the position of the arc part 46c, which is an end opposite to the third coil 50 of the pair of second coils 49 in the rotational axis direction D1, is an arc part 46c that is an end of the first coil 48 ) Can be almost the same as the location.

The number of turns of the second coil 49 and the third coil 50 may be the same, and may be less than the number of turns of the first coil 48. For example, the number of turns of the first coil 48 is 6 to 30 turns, and the number of turns of the second coil 49 and the third coil 50 is 1 to 5 turns. The number of turns of the second coil 49 and the third coil 50 may be 10% or more and 50% or less of the number of turns of the first coil 48, for example, 10% or more of the number of turns of the first coil 30 May be less than or equal to %. Each of the coil wires of the first coil 48, the second coil 49, and the third coil 50 is, for example, a wire diameter of 0.08 to 0.8 mm (for example, 0.1 to 0.3 mm), a twisting number. It may include 1 to 200 (for example, 20 to 150) litz wire. Each coil wire of the second coil 49 and the third coil 50 may have the same wire diameter and number of twists.

In addition, the inner width (IW1) of the second coil 49 and the third coil 50 in the rotation direction T1 of the heating rotor 44 is the inner width of the first coil 48 in the rotation direction T1 It may be larger than (IW2), and the outer width OW1 of the second coil 49 and the third coil 50 in the rotation direction T1 is the outer width of the first coil 48 in the rotation direction T1 ( May be smaller than OW2). That is, the second coil 49 and the third coil 50 may be disposed inside the first coil 48 in the rotation direction T1.

The core portion 47 includes a plurality of cores 51. The plurality of cores 51 are arranged at equal intervals in the rotation axis direction D1 of the heating rotor 44 so as to overlap with the straight portions 46a and 46b in the opposite direction D2, respectively. The plurality of cores 51 are disposed at positions overlapping with the second coil 49 and the third coil 50. The arrangement density of the plurality of cores 51 of the core portion 47 may be constant in the rotation axis direction D1. In addition, the magnetic permeability of the plurality of cores 51 and the distance from the coil part 46 may be the same. In addition, the first coil 48 may be disposed closer to the core portion 47 than the second coil 49 and the third coil 50 in the opposite direction D2.

Next, power supply to the coil unit 46 will be described with reference to FIGS. 6 and 7. In addition, in FIGS. 6 and 7, for convenience, the positions of the second coil 49 and the third coil 50 in the opposite direction D2 are changed. The coil unit circuit 61 generates a magnetic flux for heating the heating element 44. The coil unit circuit 61 includes a coil unit 46, a power supply unit 62, and a circuit unit 63. The coil unit 46 is included in the coil unit circuit 61 to receive power. The power supply unit 62 includes an inverter that supplies power to the coil unit 46. The circuit part 63 connects the coil part 46 and the power supply part 62. The circuit portion 63 has a switching connection portion 64. The switching connection unit 64 connects the first coil 48, the second coil 49, and the third coil 50 in series, and at the same time, switches the series connection type of each coil so that the current direction of each coil is switched. do. The switching connection part 64 is a switch disposed between the first coil 48 and the second coil 49, and the current direction of the first coil 48 and the third coil 50 and the second coil 49 The current direction is switched in the same or opposite direction. In addition, the current directions of the first coil 48 and the third coil 50 are always the same direction.

Specifically, the switching connection 64 is switched into two direct connection types (a first serial connection type and a second series connection type). In the first series connection type, as shown in Fig. 6(a), the current direction of the first coil 48 and the third coil 50 and the current direction of the second coil 49 are the same. The coils are connected in series. Since the current direction of both the second coil 49 and the third coil 50 is the same as the current direction of the first coil 48, the magnetic flux density at the outer peripheral surface 44a of the heating rotor 44 is in the direction of the rotation axis It becomes almost constant with (D1). As a result, as shown in Fig. 6(b), the temperature at the outer peripheral surface 44a of the heat generating rotating body 44 becomes substantially constant in the rotation axis direction D1. This first serial connection type is selected when the width of the paper to be fed is relatively wide. A paper having a relatively wide width refers to a paper having a width wide enough to come into contact with a portion (both ends 44x) of the heating rotor 44 opposite to the second coil 49. Hereinafter, a relatively wide paper will be described as a first paper.

On the other hand, in the second series connection type, as shown in Fig. 7(a), the current direction of the first coil 48 and the third coil 50 and the current direction of the second coil 49 are opposite. Each coil is connected in series so that it is possible. Since the current direction of the second coil 49 is opposite to the current direction of the first coil 48 and the third coil 50, a part of the magnetic flux of the first coil 48 is equal to the magnetic flux of the second coil 49 Erased by For this reason, the magnetic flux density of the outer circumferential surface 44a of the heat generating rotating body 44 becomes lower than that of the other portions at both ends 44x facing the second coil 49. As a result, as shown in Fig. 7(b), the temperature of the outer circumferential surface 44a of the heat generating rotating body 44 is lowered at both ends 44x than other portions. This second serial connection type is selected when the width of the paper to be fed is relatively narrow. A paper having a relatively narrow width means, for example, a paper having a narrow width so as not to reach both ends 44x of the heating rotor 44. Hereinafter, a relatively narrow paper will be described as a second paper.

The switching connection unit 64 performs switching to two direct connection types (a first serial connection type and a second serial connection type) in accordance with a switching signal from the control unit 65. The control unit 65 stores a set sheet (first sheet or second sheet) and outputs a switching signal corresponding to the set sheet to the switching connection unit 64. That is, when the set sheet is the first sheet, the control unit 65 outputs a switching signal for selecting the first serial connection type as the serial connection type to the switching connection unit 64. On the other hand, when the set sheet is the second sheet, the control unit 65 outputs a switching signal for selecting the second serial connection type as the serial connection type to the switching connection unit 64.

In addition, the fixing device 40 has a ratio of the magnetic flux generated by the second coil 49 and the third coil 50 to the magnetic flux generated by the first coil 48 is 50% or less (for example, 10% or more and 30% or less). Specifically, at least one of the output power of the power supply unit 62, the condition of the second coil 49 and the third coil 50, and the condition of the core unit 47 may be adjusted.

As the output power of the power supply unit 62 increases, the ratio of the magnetic flux generated by the second coil 49 and the third coil 50 to the magnetic flux generated by the first coil 48 (hereinafter, simply “ The magnetic flux ratio") increases, and can be, for example, 300 to 2000W. In addition, the conditions of the second coil 49 and the third coil 50 specifically refer to the resonance frequency, material, wire diameter, twist number, and rotation direction of the second coil 49 and the third coil 50. ) To the inner width (or outer width), and shape. The higher the resonance frequency is, the lower the magnetic flux ratio is, and may be, for example, 10 to 100 kHz. In this case, the ratio of the magnetic flux can be set to 3% to 50%. As for the material, the higher the relative magnetic permeability, the higher the magnetic flux ratio, and for example, copper or aluminum may be employed. In this case, the ratio of the magnetic flux can be set to 40% to 50%. The larger the wire diameter (more specifically, the small wire diameter), the higher the ratio of magnetic flux, for example 0.08 to 0.8 mm, preferably 0.1 to 0.3 mm. In this case, the ratio of the magnetic flux can be set to 10% to 50%. The greater the number of twists, the higher the ratio of magnetic flux, and is, for example, 1 to 200, preferably 20 to 150. In this case, the ratio of the magnetic flux can be set to 8% to 50%. The larger the inner width, the lower the magnetic flux ratio, for example, 10 to 50 mm. In this case, the ratio of the magnetic flux can be set to 40% to 50%. The larger the outer width, the higher the magnetic flux ratio, and may be, for example, 20 to 100 mm. In this case, the ratio of the magnetic flux can be set to 40% to 50%. The shape is indicated by, for example, a winding shape of a twisted wire or a winding method of a twisted wire. When the winding shape of the twisted wire is U-shaped, the ratio of the magnetic flux is increased, and may be, for example, a U-shaped, µ-shaped, or semicircle. In addition, the winding method of the twisted wire increases the ratio of the magnetic flux as it becomes denser, and may be, for example, a dense winding method or an interval winding method.

In addition, the condition of the core portion 47 is specifically the shape and density of the core portion 47, and the like. The wider the shape and the thicker the thickness, the higher the ratio of magnetic flux, and for example, each core 51 may have a width of 5 to 30 mm, or a thickness of 1 to 5 mm. The density of the core portion 47 is not defined only by the arrangement density of the cores 51, but is also defined by the magnetic permeability or the saturation magnetic flux density of each core 51. The higher the arrangement density of each core, the higher the magnetic flux ratio. The higher the magnetic permeability of each core 51, the higher the magnetic flux ratio, and may be, for example, 1000 to 3000 H/m. Further, the higher the saturation magnetic flux density, the higher the ratio of the magnetic flux, and may be, for example, 300 to 600 mT.

Next, an operation and effect of the fixing device 40 according to the first embodiment will be described, comparing with the fixing device 140 according to the comparative example shown in FIG. 8.

The fixing device 140 according to the comparative example shown in FIG. 8 includes a coil unit circuit 161 similarly to the fixing device 40 according to the first embodiment. The coil unit circuit 161 includes a coil unit 146, a power supply unit 162, and a circuit unit 163. Like the coil unit 46, the coil unit 146 overlaps the first coil 148 disposed along the rotation axis direction D1 and both ends 148x in the rotation axis direction D1 of the first coil 148 It has a pair of second coils 149 arranged. On the other hand, the coil unit 146 is provided with a coil (coil corresponding to the third coil 50 of the fixing device 40) overlapping the central part 148y in the rotation axis direction D1 of the first coil 148 I never do that. The circuit unit 163 has a switching connection unit 164 that switches the series connection type of each coil so that the current direction of each coil is switched.

In the coil unit circuit 161, the switching connection unit 164 switches between two types of series connection. In one type of series connection, each coil is connected in series so that the current direction of the first coil 148 and the current direction of the second coil 149 are the same as shown in Fig. 8(a). This serial connection type is selected when the width of the paper to be fed is relatively wide. In one serial connection type, each coil is connected in series so that the current direction of the first coil 148 and the current direction of the second coil 149 are opposite as shown in FIG. 8(b). This serial connection type is selected when the width of the paper to be fed is relatively narrow.

Here, when the width of the paper to be fed is relatively narrow, it becomes the serial connection type of FIG. 8(b) described above, and a part of the magnetic flux of the first coil 148 is erased by the magnetic flux of the second coil 149. Accordingly, the magnetic flux density of the outer circumferential surface 44a of the heating rotor 44 is lowered at both ends 44x than other portions. Accordingly, it is possible to suppress an increase in temperature of the portion of the heat generating rotating body 44 through which the paper does not pass (non-feeding portion) when passing the paper having a narrow width (see Fig. 8(b)).

On the other hand, in the case of the series connection type of FIG. 8(a) described above, the magnetic flux density of the both ends 44x, which is the portion opposite to the second coil 149 of the heating rotor 44, is of the central portion 44y. It becomes higher compared to the magnetic flux density. For this reason, the temperature rise of the heat generating rotating body 44 at both ends 44x increases compared to the central portion 44y in the rotation axis direction D1 (see Fig. 8(a)). As a result, for example, if the temperature of the heating rotor 44 is controlled so that the temperature can be fixed at the central portion 44y of the heating rotor 44, the temperature of the both ends 44x of the heating rotor 44 is relatively increased. The temperature distribution of the heating rotor 44 becomes uneven. When the temperature distribution of the heating rotor 44 is non-uniform, there is a fear of affecting the image (a difference in gloss). In addition, since the temperature of both ends 44x of the heating rotor 44 is higher than the temperature required for fixing, unnecessary energy (power) is consumed.

6 and 7, in the fixing device 40 according to the first embodiment, both ends 48x of the first coil 48 opposite to the both ends 44x of the heating rotor 44 are overlapped. As much as possible, a pair of second coils 49 are provided. In addition, the third coil 50 is provided so as to overlap with the central portion 48y of the first coil 48 that faces the central portion 44y of the heating rotor 44. Then, the series connection type of each coil is switched so that the current direction of each coil connected in series is switched. When a relatively narrow second sheet passes through, a second connection type (see FIG. 7) is selected, and the current direction of the second coil 149 is relative to the first coil 148 and the third coil 150. It becomes the opposite direction. In this case, as in the comparative example, generation of magnetic flux in the non-feeding portion of the heat generating rotating body 44 is suppressed, and an increase in the temperature of the non-feeding portion can be suppressed. In addition, when the relatively wide first sheet passes, the first connection type (see Fig. 6) is selected, and the current of the first coil 48, the second coil 49, and the third coil 50 The directions are the same as each other. In this case, the magnetic flux is generated by the third coil 50 even in the central portion 44y in which the second coil 49 is not installed. Accordingly, it is possible to suppress an increase in the temperature of both ends 44x compared to the central portion 44y of the heating rotor 44. As described above, according to the fixing device 40, the temperature distribution of the heating rotor 44 can be uniform.

In this way, the temperature distribution of the heating rotor 44 is uniform, so that a difference in gloss of an image can be suppressed. Further, energy (power) consumption in the fixing device 40 can also be reduced. For example, when the second sheet is fed, an example of maintaining the temperature of the central portion 44y of the heating rotor 44 at 150°C can be considered. In this case, as shown in FIG. 9, in the comparative example, the temperature of both ends 44x of the heating rotor 44 is higher than the temperature of the central part 44y (dashed-dotted line in FIG. 9 ), whereas the fixing device 40 In, the temperature at both ends 44x of the heat generating rotor 44 is about the same as the temperature of the central part 44y (solid line in FIG. 9). In the comparative example, as the temperature of both ends 44x increases, a lot of power (for example, 780W) is required, whereas in the fixing device 40, the heating rotor 44 is uniformly heated, so that the power is reduced (for example, 700W). can do.

Further, in the fixing device 40, the number of turns of the second coil 49 is smaller than that of the first coil 48. Specifically, the number of turns of the second coil 49 is 10% or more and 50% or less (eg, 30% or less) of the number of turns of the first coil 48. Accordingly, since the magnetic flux density of the magnetic field generated by the second coil 49 is reduced, it is possible to effectively suppress an increase in the temperature of the both ends 44x compared to the central portion 44y of the heating rotor 44.

In addition, the inner width (IW1) of the second coil 49 and the third coil 50 in the rotation direction T1 of the heating rotor 44 is the inner width of the first coil 48 in the rotation direction T1 It is larger than (IW2), and the outer width OW1 of the second coil 49 and the third coil 50 in the rotation direction T1 is the outer width OW2 of the first coil 48 in the rotation direction T1 Less than That is, the second coil 49 and the third coil 50 are disposed inside the first coil 48 in the rotation direction T1. Accordingly, it is possible to prevent the magnetic flux of the second coil 49 and the third coil 50 from being generated in a region where the magnetic flux of the first coil 48 is not affected, and the temperature of the heating rotor 44 Uniform distribution can be achieved.

In addition, the second coil 49 and the third coil 50 have the same distance from the heat generating rotating body 44 in the opposite direction D2 and the number of turns. Accordingly, the magnetic flux generated by the second coil 49 and the third coil 50 can be made to the same degree, and the temperature distribution of the heating rotor 44 can be made more uniform.

In addition, in the fixing device 40, the ratio of the magnetic flux generated by the second coil 49 and the third coil 50 to the magnetic flux generated by the first coil 48 is 50% or less (for example, 10% or more and 30% or less), the output power of the power supply unit 162, the resonance frequency of the second coil 49 and the third coil 50, material, wire diameter, number of twists, inner or outer width, shape, core At least one of the shape and density of the core is adjusted. In this way, by suppressing the magnetic flux density of the magnetic flux generated by the second coil 49 and the third coil 50, the heating rotor 44 is influenced by the second coil 49 or the third coil 50. It is possible to achieve a uniform temperature distribution of the heating rotor 44 by suppressing a situation in which only a portion of the temperature rises.

[2nd embodiment]

Next, an image forming apparatus according to a second embodiment will be described with reference to FIG. 10 in addition to FIGS. 1 to 9. In addition, for each of the following embodiments including the present embodiment, differences from the above-described first embodiment will be mainly described, and redundant descriptions will be omitted.

The image forming apparatus 1A includes a fixing apparatus 40A. The fixing device 40A includes a coil portion 46A. The coil part 46A is in each coil (the first coil 48, the second coil 49, and the third coil 50) included in the coil part 46 of the first embodiment, and a fourth coil ( 71A) and a fifth coil 72A are further provided.

The fourth coil 71A is disposed to overlap both ends of the first coil 48 and the second coil 49 in the rotation axis direction D1 in the opposite direction D2. The fifth coil 72A is disposed to overlap the central portion of the rotation axis direction D1 of the first coil 48 and the third coil 50 in the opposite direction D2.

The fourth coil 71A and the fifth coil 72A may have the same distance from the heating rotating body 44 in the opposite direction D2. The distance from the outer peripheral surface 44a of the heating rotor 44 to the fourth coil 71A and the fifth coil 72A is less than the distance from the outer peripheral surface 44a to the second coil 49 and the third coil 50 It can be short. In addition, the fourth coil 71A and the fifth coil 72A may be disposed adjacent to each other at ends.

The length obtained by adding the length in the rotation axis direction D1 of the pair of fourth coils 71A and the length in the rotation axis direction D1 of the fifth coil 72A is the rotation axis direction D1 of the pair of second coils 49 ) May be substantially the same as a length obtained by adding the length of the third coil 50 and the length of the rotation axis direction D1 of the third coil 50. In addition, the end positions of the pair of fourth coils 71A on the side adjacent to the fifth coil 72A and the opposite side are on the side opposite to the side of the pair of second coils 49 adjacent to the third coil 50 It may be substantially the same as the end position of the rotation axis direction (D1). In addition, the ratio of the lengths of the fourth coil 71A and the fifth coil 72A in the rotation axis direction D1 is the length of the second coil 49 and the third coil 50 in the rotation axis direction D1. May be different from rain. Specifically, the length of the fourth coil 71A in the rotation axis direction D1 may be shorter than the length in the rotation axis direction D1 of the second coil 49. In addition, the length of the fifth coil 72A in the rotation axis direction D1 may be longer than the length in the rotation axis direction D1 of the third coil 50.

The 4th coil 71A and the 5th coil 72A are connected in series to the 1st coil 48, the 2nd coil 49, and the 3rd coil 50 by the switching connection part 64. The switching connection part 64 switches the series connection type of the 1st coil 48, the 2nd coil 49, the 3rd coil 50, the 4th coil 71A, and the 5th coil 72A. Further, the current directions of the first coil 48, the third coil 50, and the fifth coil 72A are always the same direction. In addition, the current direction of each of the second coil 49 and the fourth coil 71A may be the same or opposite to the first coil 48.

As described above, in the fixing device 40A according to the second embodiment, the fourth coil 71A and the fifth coil 72A have a length ratio different from the ratio of the lengths of the second coil 49 and the third coil 50. ) Is provided. Accordingly, compared to the fixing device 40 according to the first embodiment, it is possible to achieve a uniform temperature distribution of the heating rotor 44 while responding to a more detailed difference in paper size.

That is, a case in which a sheet having a wide width enough to come into contact with a portion of the heating rotor 44 facing the fourth coil 71A is fed. In this case, as shown in Fig. 11(a), the current directions of all coils become the same direction. For this reason, the magnetic flux density with respect to the rotation axis direction D1 can be made about the same, and the temperature distribution of the heat generating rotating body 44 can be made uniform. In addition, although it does not come into contact with the portion of the heating rotor 44 that faces the fourth coil 71A, it is conceivable that a paper with a width wide enough to contact the portion that faces the second coil 49 is fed. . In this case, as shown in Fig. 11(b), only the current direction of the fourth coil 71A becomes the direction opposite to that of the other coils. Accordingly, when the paper is fed, the generation of magnetic flux in the non-feeding portion of the heating rotor 44 can be suppressed, thereby suppressing an increase in temperature of the non-feeding portion. In addition, a case in which paper that does not reach the portion of the heating rotor 44 opposite to the second coil 49 is fed may be considered. In this case, as shown in Fig. 11(c), in addition to the fourth coil 71A, the current direction of the second coil 49 is opposite to that of the other coils. Accordingly, when the paper is fed, the generation of magnetic flux in the non-feeding portion of the heating rotor 44 can be suppressed, thereby suppressing an increase in temperature of the non-feeding portion. In Fig. 11, some configurations of the fixing device 40A are omitted.

In addition, in the fixing device 40A, the ratio of the magnetic flux generated by the fourth coil 71A and the fifth coil 72A to the magnetic flux generated by the first coil 48 is 50% or less (for example, 10 % Or more and 30% or less), at least one of the output power of the power supply unit 62, the condition of the fourth coil 71A and the fifth coil 72A, and the condition of the core unit 47 may be adjusted. . The output power of the power supply unit 62 and the conditions of the core unit 47 are the same as those of the first embodiment described above.

Specifically, the condition of the fourth coil 71A and the fifth coil 72A is the resonance frequency, material, wire diameter, twist number, and rotation direction T1 of the fourth coil 71A and the fifth coil 72A. Inner width (or outer width), and shape. The resonance frequency is, for example, 10 to 100 kHz. The material is, for example, copper or aluminum. The wire diameter (more specifically, the small wire diameter) is, for example, 0.08 to 0.8 mm (for example, 0.1 to 0.3 mm). The number of twists is, for example, 1 to 200 (eg, 20 to 150). The inner width is, for example, 10 to 50 mm. The outer width is, for example, 20 to 100 mm. The shape is represented by, for example, a winding shape of a twisted wire or a winding method of a twisted wire. The winding shape of the twisted wire is, for example, a U-shape, a C-shape, or a semicircle. In addition, the winding method of the twisted wire is, for example, a dense winding method or an interval winding method.

[Third embodiment]

Next, an image forming apparatus according to a third embodiment will be described with reference to FIGS. 1 to 11 and FIGS. 12 to 16.

The coil unit 46 according to the third embodiment shown in FIG. 12A includes a second coil 49 and a third coil 50 as in the first embodiment. Ends of the second coil 49 and the third coil 50 (circular portion 46c) are disposed adjacent to each other in the connection area 46x. In this case, since there is no large gap between the coils, it is easier to keep the temperature distribution of the heating rotor 44 uniform compared to the case where there is a large gap between the coils. However, for example, when current in the same direction is passed to the second coil 49 and the third coil 50, the current of the second coil 49 and the current of the third coil 50 are opposite in the connection area 46x. Because they flow in the direction, they erase magnetic fluxes from each other. Therefore, as shown in Fig. 13(a), the magnetic flux density of the region TS1 of the heat generating rotor 44 facing the connection region 46x is lower than that of the other regions of the heat generating rotor 44. As a result, there is a fear that the temperature distribution of the heating rotor 44 becomes uneven.

14 and 15, the image forming apparatus 1B according to the third embodiment includes a fixing device 40B. The fixing device 40B includes a core portion 47B.

The core portion 47B includes a plurality of cores 51B (connecting portions) overlapping the connection region 46x in the opposite direction D2. Further, the core portion 47B is provided with a plurality of cores 51 (main portions) as cores other than the core 51B. The plurality of cores 51 are arranged side by side at equal intervals in the rotation axis direction D1 in a region excluding a region facing the connection region 46x (a region in which the plurality of cores 51B are provided). The core 51B and the core 51 may have the same magnetic permeability.

The plurality of cores 51B and the plurality of cores 51 have different arrangement densities in the rotation axis direction D1. That is, the plurality of cores 51 are disposed at a constant interval from each other, whereas the plurality of cores 51B are disposed in a state adjacent to each other (contact). For this reason, compared with the plurality of cores 51, the plurality of cores 51B have a higher arrangement density in the rotation axis direction D1.

Here, in the connection region 46x, magnetic fluxes generated from the second coil 49 and the third coil 50 easily influence each other as described above. Accordingly, in the region TS1 (FIG. 13A) facing the connection region 46x of the heat generating rotating body 44, a magnetic field different from the other regions is likely to be generated.

In this regard, in the present embodiment, the arrangement density of the plurality of cores 51B overlapping the connection region 46x in the opposite direction D2 is higher than that of the plurality of cores 51 which are other cores. Accordingly, as shown in FIG. 13B, the magnetic flux density in the region around the region TS1 in which the magnetic flux density of the heating rotor 44 is lowered can be increased. As a result, it is possible to achieve uniformity of the temperature distribution in the rotation axis direction D1.

Further, the configuration of making the temperature distribution of the heating rotating body 44 uniform as a whole by adjusting the magnetic flux density around the region where the magnetic flux density of the heating rotating body 44 is low is not limited to the configuration of the fixing device 40B. For example, like the fixing device 40X of the image forming apparatus 1X shown in FIG. 16, a plurality of cores 51X in which the core portion 47X overlaps the connection area 46x in the opposite direction D2, and others A plurality of cores 51 which are cores may be provided. The plurality of cores 51X and the plurality of cores 51 have the same arrangement density and permeability. On the other hand, the plurality of cores 51X and the plurality of cores 51 have different distances from the heating rotating body 44 in the opposite direction D2. Specifically, the plurality of cores 51X have a closer distance from the heat generating rotating body 44 than the plurality of cores 51. Accordingly, the magnetic flux density of the peripheral region of the region where the magnetic flux density of the heating rotor 44 is lowered (the region TS1 facing the connection region 46x) can be increased. As a result, it is possible to achieve uniformity of the temperature distribution in the rotation axis direction D1.

In addition, the arrangement density of each core of the core portion and the distance from the heating rotor 44 are made equal to each other, and the permeability of the plurality of cores overlapping the connection region 46x in the opposite direction D2, and other cores The permeability of can be different. Specifically, the permeability of the core overlapping the connection region 46x in the opposite direction D2 can be made higher than that of other cores. Accordingly, the magnetic flux density of the peripheral region of the region (region facing the connection region 46x) in which the magnetic flux density of the heating rotor 44 is lowered can be increased. As a result, it is possible to achieve uniformity of the temperature distribution in the rotation axis direction D1.

Further, like the fixing device 40A of the second embodiment, the fourth coil 71A and the fifth coil 72A are provided, and the fourth coil 71A and the fifth coil 72A are the second coil 49 ) And a connection region 73x having the same relationship as the connection region 46x of the third coil 50 (image forming apparatus 1) C) (see FIG. 18). The fixing device 40C includes a core portion 47C. The core portion 47C includes a connection region 46x and a plurality of cores 51C (connection portions) overlapping the connection region 73x in the opposite direction D2. Further, the core portion 47C is provided with a plurality of cores 51 (main portions) as cores other than the core 51C. The plurality of cores 51 are arranged side by side at equal intervals in the rotation axis direction D1, except for a region in which the plurality of cores 51C are installed. The core 51C and the core 51 have the same magnetic permeability.

The plurality of cores 51C and the plurality of cores 51 have different arrangement densities in the rotation axis direction D1. That is, the plurality of cores 51 are disposed at a constant interval from each other, while the plurality of cores 51C are disposed in a state adjacent to each other (contact). For this reason, compared with the plurality of cores 51, the plurality of cores 51C have a higher arrangement density in the rotation axis direction D1.

In this way, the arrangement density of the plurality of cores 51C overlapping the connection region 46x and the connection region 73x in the opposite direction D2 is higher than that of the plurality of cores 51 which are other cores. Accordingly, it is possible to increase the magnetic flux density in the peripheral region of the region where the magnetic flux density of the heating rotor 44 is lowered (a region facing the connection region 46x and the connection region 73x). As a result, it is possible to achieve uniformity of the temperature distribution in the rotation axis direction D1.

[4th embodiment]

Next, like the third embodiment, a fourth embodiment will be described with reference to Figs. 1 to 16.

In the above-described third embodiment, the ends of the second coil 49 and the third coil 50 of the coil unit 46 are disposed adjacent to each other in the connection region 46x. In contrast, in the fourth embodiment, as shown in Fig. 12(b), the ends of the second coil 49h and the third coil 50h of the coil unit 46h are separated from each other in the connection region 46y. Is placed. By being spaced apart in this way, the second coil 49h and the third coil 50h can be easily disposed.

Here, when the second coil 49h and the third coil 50h are spaced apart from each other, even when a current flows in the same direction through the second coil 49h and the third coil 50h, the same as in the third embodiment. It is difficult to cancel the same magnetic flux. However, there is a region in which the coil does not exist in the connection region 46y, and magnetic flux does not occur in that region. Accordingly, as shown in FIG. 13(a), the magnetic flux density of the region TS1 of the heat generating rotor 44 facing the connection region 46y is lower than that of other regions of the heat generating rotor 44. As a result, there is a fear that the temperature distribution of the heating rotor 44 becomes uneven. Even in such a case, the region in which the magnetic flux density in the heating rotor 44 is lowered by the fixing device 40B (see FIGS. 14 and 15) or the fixing device 40X (see FIG. 16) described in the third embodiment. (Area TS1 facing the connection region 46y) The magnetic flux density in the peripheral region can be increased (Fig. 13(b)). As a result, it is possible to achieve uniformity of the temperature distribution in the rotation axis direction D1.

Also, like the fixing device 40A of the second embodiment, the fourth coil and the fifth coil are provided, and the fourth coil and the fifth coil are connected to the second coil 49h and the third coil 50h. You can think of the case of having a connection area of the same relationship as ). Even in this case, by configuring the core to increase the magnetic flux density around the region of the heating rotor 44 facing the connection region between the fourth coil and the fifth coil, it is possible to achieve uniform temperature distribution in the direction of the rotation axis D1. I can.

[Fifth embodiment]

Next, a fifth embodiment will be described in FIGS. 1 to 16 with further reference to FIG. 17.

In the above-described third embodiment, the ends of the second coil 49 of the coil portion 46 and the third coil 50 are disposed adjacent to each other in the connection region 46x. In contrast, in the fifth embodiment, as shown in Fig. 12(c), the ends of the second coil 49i and the third coil 50i of the coil part 46i are arranged to overlap in the opposite direction D2. do. In this case, if current flows in the same direction in the second coil 49i and the third coil 50i, the current flows in the same direction in the second coil 49i and the third coil 50i even in the connection region 46z. , The magnetic fluxes generated from the coil interfere constructively with each other.

In this case, as shown in FIG. 17(a), the region TS2 of the heat generating rotor 44 facing the connection region 46z has a higher magnetic flux density than other regions of the heat generating rotor 44. As a result, there is a fear that the temperature distribution of the heating rotor 44 becomes uneven.

In this embodiment, as opposed to increasing the magnetic flux density around the region where the magnetic flux density is lowered in the third embodiment, the magnetic flux density around the region where the magnetic flux density is increased is reduced. That is, for example, the arrangement density of the plurality of cores overlapping the connection region 46z in the opposite direction D2 is lower than that of the other plurality of cores. In addition, for example, the distance from the heating rotor 44 of the plurality of cores overlapping in the opposite direction D2 with the connection region 46z is made larger than the distance from the heating rotor 44 of the other plurality of cores. . Further, for example, the permeability of the plurality of cores overlapping the connection region 46z in the opposite direction D2 is made lower than that of the other plurality of cores. Accordingly, as shown in FIG. 17B, the magnetic flux density of the region around the region TS3 in which the magnetic flux density of the heating rotor 44 is increased can be reduced. As a result, it is possible to achieve uniformity of the temperature distribution in the rotation axis direction D1.

Further, like the fixing device 40A of the second embodiment, the fourth coil and the fifth coil are provided, and the fourth coil and the fifth coil are connected to the second coil 49i and the third coil 50i. A case in which a connection region having the same relationship as) is provided is considered. Even in this case, by configuring the core portion to lower the magnetic flux density in the peripheral region of the region of the heat generating rotor 44 facing the connection region of the fourth coil and the fifth coil, uniform temperature distribution in the rotation axis direction D1 is achieved. I can plan.

[6th embodiment]

Next, an image forming apparatus according to a sixth embodiment will be described with reference to FIGS. 19 to 22 in addition to FIGS. 1 to 18.

As shown in Fig. 19, the image forming device 1D includes a fixing device 40D. 19 shows only the configuration of the fixing device 40D according to the coil unit 46, and other configurations are omitted.

In the fixing device 40D, a control unit (FIG. 7:65) controls at least one of the power supply unit 62 and the switching connection unit 64. The control unit 65 individually sets at least one control pattern of the power supply unit 62 and the switching connection unit 64 according to the paper feeding condition.

As described above, the control unit 65 controls the switching connection unit 64 to be converted into two serial connection types (a first serial connection type and a second serial connection type) by outputting a switching signal to the switching connection unit 64. do. In the first series connection type, as shown in Fig. 19(a), the current direction of the first coil 48 and the third coil 50 and the current direction of the second coil 49 are the same, Each coil is connected in series. Further, in the second series connection type, as shown in Fig. 19(b), the current direction of the first coil 48 and the third coil 50 and the current direction of the second coil 49 are opposite to each other. As far as possible, each coil is connected in series. As described above, the current directions of the first coil 48 and the third coil 50 are always the same. These two types of serial connection are examples of control patterns for controlling the switching connection unit 64, respectively.

In addition, by controlling the power supply by the power supply unit 62, the control unit 65 can set a control pattern different from the control pattern according to the two series connection types described above. That is, according to the control pattern according to the two series connection types described above, power is supplied to all coils, but the control pattern does not supply power to some of the coils (stopping the supply of power by the power supply unit 62). The pattern to set) may also be included. For example, a control pattern that does not supply power to the second coil 49 (Fig. 19(c)) or a control pattern that does not supply power to the third coil 50 (Fig. 19(d)) is also controlled. It can be included in the pattern.

Since it is possible to set various types of control patterns as described above, temperature distributions of various shapes can be implemented in the direction of the rotation axis D1. That is, in addition to the temperature distribution (ga) and the temperature distribution (gb) according to the control pattern according to the two series connection types shown in FIG. 20, the temperature according to the control pattern that does not supply power to the second coil 49 The distribution gc and the temperature distribution gd according to the control pattern in which power is not supplied to the third coil 50 can also be realized. Accordingly, it is possible to achieve uniform temperature distribution of the heating rotor 44 according to various situations.

In addition, the method of controlling the power supply of the power supply unit 62 by the control unit 65 is not particularly limited, for example, a bypass route is provided in parallel with each coil in the series connection circuit, and a switch controlled by the control unit 65 By selecting the coil or the bypass route by means of, it is possible to control the presence or absence of power supply to each coil.

Fig. 21 shows various control patterns. 21(a) to 21(g) show control patterns A1 to A7, respectively. In the control pattern A1, the above-described first series connection type is selected as the series connection type, and power is supplied to all coils (FIG. 21(a)). In the control pattern A2, the first series connection type (or the above-described second series connection type) is selected as the series connection type, and power is supplied only to the first coil 48 (Fig. 21(b)). In the control pattern A3, the first series connection type (or the second series connection type) is selected as the series connection type, and power is supplied only to the first coil 48 and the third coil 50 (Fig. 21 (c)). In the control pattern A4, the second series connection type is selected as the series connection type, and power is supplied to all the coils (Fig. 21(d)). In the control pattern A5, the first series connection type (or the second series connection type) is selected as the series connection type, and power is supplied only to the third coil 50 (FIG. 21(e)). In the control pattern A6, the first series connection type is selected as the series connection type, and power is supplied only to the second coil 49 (Fig. 21(f)). In the control pattern A7, the first series connection type is selected as the series connection type, and power is supplied only to the first coil 48 and the second coil 49 (Fig. 21(g)).

22 shows an example of setting such a control pattern. Fig. 22 shows an appropriate control pattern according to the condition of the type of paper, paper width, and paper passing or between paper and paper. The type of paper is either plain paper or thick paper. Plain paper is paper with a base weight of 60.2 to 104.7 g/m ² , and thick paper is paper with a basis weight of 104.7 to 216.0 g/m ² . The paper passing is a state in which the paper is passing through the heat generating rotating body 44, and includes at the beginning of feeding, at the time of continuous feeding of multiple sheets, and at the end of feeding. In addition, between the paper and the paper means when preparing to feed. In the case of passing through the sheet, whether the target temperature (target temperature of the heating rotor 44) is equal to or higher than +3°C, within the target temperature ±3°C, or lower than the target temperature -3°C is a condition for determining the control pattern. Further, in the case of between the sheet and the sheet, the control pattern is set when the temperature is below the target temperature, and when the temperature is higher than the target temperature, the setting (change) of the control pattern is not made. In addition, in the example of setting the control pattern shown in FIG. 22, the length in the rotation axis direction D1 of the first coil 48 is 300 mm, and the length in the rotation axis direction D1 of the second coil 49 and the third coil 50 This is an example of setting when each is 100 mm.

For example, when the paper type is plain paper, the paper width is 151 mm to 200 mm, the paper is passing through, and the target temperature of the heating rotor 44 is +3°C or higher, the control pattern A5 (Fig. 21(e)) is selected. . Further, when the paper type is plain paper, the paper width is 101 mm to 150 mm, the paper is passing through, and the target temperature of the heat generating rotor 44 is equal to or higher than +3°C, the control pattern OFF is selected. The control pattern OFF indicates a case in which the control pattern is not newly set.

In addition, the above-described control pattern setting example is only an example, and the condition for determining the control pattern is only an example. For example, it has been described that the condition is whether the paper is being passed through or between the paper and the paper, but more specifically, the time of preparation for paper feeding, the time of starting paper feeding, the time of continuous feeding, and the time of paper feeding may be set as individual conditions. Since the control pattern is determined according to the feeding situation in this way, for example, it is possible to suppress the power supply during non-feeding compared to the feeding situation, thereby achieving uniform temperature distribution of the heating rotor 44 according to various situations. .

In addition, since the control pattern is determined according to the width of the paper as shown in the control pattern of FIG. 22, an appropriate control pattern according to various paper widths is selected, and the temperature distribution of the heating rotor 44 when feeding paper of various widths Uniformization can be achieved. In this way, since the control pattern is determined according to the thickness of the paper, it is possible to achieve a uniform temperature distribution of the heating rotor 44 when paper of various thicknesses is fed.

In addition, since the control pattern is determined according to the difference between the measured temperature of the heating rotor 44 and the target temperature, an appropriate control pattern can be selected according to the temperature situation of the heating rotor 44.

[7th embodiment]

Next, an image forming apparatus according to a seventh embodiment will be described with reference to FIGS. 23 to 25 in addition to FIGS. 1 to 22.

23 and 24, the image forming apparatus 1E includes a fixing apparatus 40E. The fixing device 40E includes a coil portion 46A (see Figs. 10 and 11) similarly to the fixing device 40 of the second embodiment. In Figs. 23 and 24, only the configuration according to the coil unit 46A of the fixing device 40E is shown, and other configurations are omitted.

In the fixing device 40E, similarly to the fixing device 40D according to the sixth embodiment, the control unit 65 controls at least one of the power supply unit 62 and the switching connection unit 64. Various control patterns by the control unit 65 will be described. In addition, as described above, the current directions of the first coil 48, the third coil 50, and the fifth coil 72A are always the same.

23 shows control patterns B1 to B6. In the control pattern B1, a series connection type in which the current directions of all coils are the same is selected, and power is supplied to all coils (Fig. 23(a)). In the control pattern B2, power is supplied only to the first coil 48 (Fig. 23(b)). In the control pattern B3, a series connection type in which the current directions of all coils except for the fourth coil 71A are the same is selected, and power is supplied to all coils except for the fourth coil 71A (Fig. 23 ( c)). In the control pattern turn B4, a series connection type in which only the current direction of the fourth coil 71A is opposite to the current direction of the other coils is selected, and power is supplied to all coils (Fig. 23(d)). In the control pattern B5, a series connection type in which the current direction of the second coil 49 and the current direction of the first coil 48 are opposite is selected, and power is applied to all coils except for the fourth coil 71A. The supply is made (Fig. 23(e)). In the control pattern B6, power is supplied to all coils except for the second coil 49 and the fourth coil 71A (Fig. 23(f)).

24 shows control patterns B7 to B12. In the control pattern B7, power is supplied to all coils except for the first coil 48, the second coil 49, and the fourth coil 71A (Fig. 24(a)). In the control pattern B8, a series connection type in which the current direction of the second coil 49 and the fourth coil 71A and the current direction of other coils are opposite is selected, and all coils except the fifth coil 72A are selected. Power is supplied to (Fig. 24(b)). In the control pattern B9, power is supplied only to the fifth coil 72A (Fig. 24(c)). In the control pattern B10, power is supplied only to the third coil 50 (Fig. 22(d)). In the control pattern B11, a series connection type in which the current direction of the second coil 49 and the current direction of the first coil 48 are the same is selected, and power is supplied only to the second coil 49 (Fig. 24). (e)). In the control pattern B12, a series connection type in which the current direction of the fourth coil 71A and the current direction of the first coil 48 are the same is selected, and power is supplied only to the fourth coil 71A (Fig. 24). (f)).

Fig. 25 shows an example of setting such a control pattern. Various conditions for determining the control pattern are the same as those of the control pattern in Fig. 22 described in the fifth embodiment. In addition, in the example of setting the control pattern shown in FIG. 25, the length of the rotation axis direction D1 of the first coil 48 is 300 mm, and the length of the rotation axis direction D1 of the second coil 49 and the third coil 50 A is an example of setting when the length in the rotation axis direction D1 of the fourth coil 71A is 50 mm, and the length in the rotation axis direction D1 of the fifth coil 72A is 200 mm, respectively.

For example, when the paper type is plain paper, the paper width is 151 mm to 200 mm, the paper is passing through, and the target temperature of the heating rotor 44 is +3°C or higher, the control pattern B9 is selected. Further, when the paper type is plain paper, the paper width is less than 100 mm, the paper is passing through, and the target temperature of the heat generating rotor 44 is equal to or higher than +3°C, the control pattern OFF is selected. The control pattern OFF indicates a case in which the control pattern is not newly set.

[8th embodiment]

Next, an image forming apparatus according to an eighth embodiment will be described with reference to FIGS. 26 and 27 in addition to FIGS. 1 to 25.

As shown in Fig. 26, the image forming apparatus 1F includes a fixing apparatus 40F. Similar to the fixing device 40A of the second embodiment, the fixing device 40F includes a coil portion 46A (see Figs. 10 and 11). Further, the fixing device 40F is provided with a temperature detection sensor 80 that detects the temperature of the heating rotor 44. Also, in FIG. 26, only the configuration according to the coil part 46A and the temperature detection sensor 80 of the configuration of the fixing device 40F is shown. In addition, in FIG. 26, for convenience of explanation, the temperature detection sensor 80 is shown as being disposed on the coil part 46A, but in fact, the temperature detection sensor 80 is directly under or around the heating rotor 44 Is placed in

The temperature detection sensor 80 may include a first temperature detection sensor 81, a second temperature detection sensor 82, and a third temperature detection sensor 83. The first temperature detection sensor 81 detects the temperature of the region of the heating rotor 44 overlapping the central portion in the width direction of the first coil 48, the third coil 50, and the fifth coil 72A. . The second temperature detection sensor 82 includes a heating rotor 44 overlapping a portion where the first coil 48, the second coil 49, and the fifth coil 72A overlap each other and in the opposite direction D2. The temperature of the area is detected. The third temperature detection sensor 83 detects the temperature of the heating rotor 44 overlapping the second coil 49 and the fourth coil 71A overlapping each other in the opposite direction D2.

From the value of the temperature detection sensor 80, it may be determined whether the temperature distribution of the heating rotor 44 is in an abnormal state. Accordingly, it becomes possible to determine whether or not a paper of an incorrect (different from the setting) size is being fed. Hereinafter, it will be described in detail with reference to FIG. 27.

Fig. 27 is a diagram showing the temperature distribution in the heat generating rotor 44 for each paper size (actual size) of paper actually fed to a paper size (set size) that has been set in advance. Here, in the fixing device 40F, the first paper S1, the second paper S2 wider than the first paper, and the third paper S3 wider than the second paper can be fed. In addition, the length of the first coil 48 in the rotation axis direction D1 is larger than the width of the third paper S3. Further, the length of the third coil 50 in the rotation axis direction D1 is smaller than the width of the second paper S2 and larger than the width of the first paper S1. Further, the length of the fifth coil 72A in the rotation axis direction D1 is smaller than the width of the third paper S3 and larger than the width of the second paper S2. By using a sheet and a coil of this size, it is possible to appropriately determine a feeding error by the temperature detection sensor 80 described above.

In addition, in order to improve the accuracy of the determination of the feeding error by the temperature detection sensor 80, the length of the rotation axis direction D1 of the first coil 48 is preferably 5 to 10% larger than the width of the third paper S3. Do. In addition, the length of the third coil 50 in the rotation axis direction D1 is preferably 5 to 10% larger than the width of the first paper S1. In addition, the length of the fifth coil 72A in the rotation axis direction D1 is preferably 5 to 10% larger than the width of the second paper S2.

First, a case where the set size and the actual size coincide, that is, a case where no paper feeding error has occurred will be described. For example, when the set size is the size of the third sheet S3, the current directions of all coils become the same direction. In this state, when the third paper S3 having a width larger than that of the fifth coil 72A is fed (Fig. 27(a)), the detection portions of all the temperature detection sensors 80 become the feeding unit. Therefore, the temperature detected by each of the first temperature detection sensor 81, the second temperature detection sensor 82, and the third temperature detection sensor 83 becomes the same degree. In this way, when the set size is the size of the third paper S3 and the values of all the temperature detection sensors 80 become the same, it can be determined that no paper feed error has occurred.

Further, for example, when the set size is the size of the second sheet S2, only the current direction of the fourth coil 71A becomes the direction opposite to that of the other coils. In this state, when the second paper S2, which is wider than the third coil 50 and narrower than the fifth coil 72A, is fed (Fig. 27(e)), the third temperature is detected as the non-feeding part. Only the value of the sensor 83 is lowered by a predetermined value compared with the values of the first temperature detection sensor 81 and the second temperature detection sensor 82. In this way, when the set size is the size of the second paper S2 and only the value of the third temperature detection sensor 83 is lowered by a predetermined value, it can be determined that no paper feeding error has occurred.

Further, for example, when the set size is the size of the first sheet S1, in addition to the fourth coil 71A, the current direction of the second coil 49 is also opposite to that of the other coils. In this state, when the first paper S1, which is narrower than the third coil 50, is fed (Fig. 27(i)), the second temperature detection sensor 82 and the second temperature detection sensor 82, which become the non-feeding part, are 3 The value of the temperature detection sensor 83 is lowered by a predetermined value compared with the value of the first temperature detection sensor 81. In this way, the set size is the size of the first paper S1, and the values of the second temperature detection sensor 82 and the third temperature detection sensor 83 are compared with the value of the first temperature detection sensor 81 When it is lowered by a predetermined value, it can be determined that a feeding error has not occurred.

In contrast, when the set size and the actual size do not match, that is, when a feeding error occurs, the temperature detection sensor 80 performs a temperature detection different from the case where the above-described feeding error does not occur. For example, when the set size is the paper size of the third paper S3 and the second paper S2 is fed (Fig. 27(d)), only the value of the third temperature detection sensor 83 detects the first temperature. It increases compared with the values of the sensor 81 and the 2nd temperature detection sensor 82. The temperature difference is caused by a part of the heat being transferred to the paper in the part where the paper passes, and the temperature of the paper passing part is lowered compared to the part where the paper does not pass. In this case, since the values of all the temperature detection sensors 80 must be of the same degree, the controller 65 can determine that a feeding error has occurred. In addition, the temperature detection situation by the temperature detection sensor 80 is the situation when the second paper S2 is fed (the detection values of the first and second temperature detection sensors 81 and 82 are almost the same, and the third Since the detection value of the temperature detection sensor 83 is different), the control unit 65 changes the set size to the size of the second paper S2. Accordingly, when the temperature detection situation detected by the temperature detection sensor 80 is different from the temperature detection situation according to the set size, the control unit 65 may change to an appropriate set size.

[9th embodiment]

Next, with reference to FIG. 28 in addition to FIGS. 1 to 27, an image forming apparatus according to a ninth embodiment will be described.

As shown in Fig. 28, the image forming apparatus 1G includes a fixing apparatus 40G. The fixing device 40G includes a coil part 46 similarly to the fixing device 40 of the first embodiment. Further, the fixing device 40G is provided with a temperature detection sensor 80G that detects the temperature of the heating rotor. In addition, in FIG. 28, only the configuration according to the coil unit 46 and the temperature detection sensor 80G among the configurations of the fixing device 40G is shown. In addition, in FIG. 28, for convenience of explanation, the temperature detection sensor 80G is shown as being disposed on the coil part 46, but in reality the temperature detection sensor 80G is directly under or around the heating rotor 44. Is placed in

In the fixing device 40F according to the eighth embodiment shown in FIG. 26, three temperature detection sensors 80 are provided for the three-layered coil portion 46A, but the fixing device 40G has a two-layer structure. Two temperature detection sensors 80 are provided for the coil part 46. That is, the first temperature detection sensor 81G and the second temperature detection sensor 83G are provided.

The first temperature detection sensor 81G detects the temperature of the region of the heating rotor 44 overlapping the center of the rotation axis direction D1 of the first coil 48 and the third coil 50 in the opposite direction D2. do. The second temperature detection sensor 83G includes a portion of the first coil 48 and the second coil 49 overlapping each other in the opposite direction D2 and the region of the heating rotor 44 overlapping in the opposite direction D2. The temperature is detected.

According to this configuration, it is possible to detect a feeding error even in a coil configuration of a two-layer structure composed of the first coil 48, the second coil 49, and the third coil, like the coil unit 46. That is, according to the temperature of the first temperature detection sensor 81G and the temperature of the second temperature detection sensor 83G, an error of the actual size with respect to the set size may be detected.

As described above, preferred embodiments of the present invention have been described, but the present invention is not limited to the above embodiments. For example, although it has been described that the number of turns of the second coil 49 and the third coil 50 is less than the number of turns of the first coil 48, it is not limited thereto, and may be equal to or greater than the number of turns of the first coil. .

In addition, the inner width IW2 of the second coil 49 and the third coil is larger than the inner width IW1 of the first coil 48, and the outer width OW2 of the second coil 49 and the third coil is first Although it has been described that it is larger than the outer width OW1 of the coil 48, it is not limited thereto. That is, the inner width IW2 may be equal to or smaller than the inner width IW1, and the outer width OW2 may be equal to or greater than the outer width OW1.

Also, although it has been described that the number of turns of the second coil 49 and the third coil 50 is the same, it may be different. In addition, it is not always necessary that the first coil 48 be disposed closer to the core portion 47 than the second coil 49 and the third coil 50. In addition, the core portion 47 is not necessarily installed. In addition, each coil does not necessarily have to be a separate coil, and for example, the first coil 48 and the third coil 50 may always flow in the same direction as an integral coil.

The above-described embodiments are merely exemplary, and various modifications and equivalent other embodiments are possible from those of ordinary skill in the art. Therefore, the true technical scope of the present invention should be determined by the technical spirit of the invention described in the following claims.

1, 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1X: image forming device
40, 40A, 40B, 40C, 40D, 40E, 40F, 40G, 40X: Fusing device
44: heating rotor 44a: outer peripheral surface
46, 46A, 46h, 46i: coil part 46c: arc part
46x, 46y, 46z, 73x: connection area 47, 47B, 47C, 47X: core part
48: first coil 48x: both ends
48y: central portion 49, 49h, 49i: second coil
50, 50h, 50i: third coil 51, 51B, 51C, 51X: core
62: power supply unit 63: circuit unit
64: switching connection portion 65: control unit
71A: fourth coil 72A: fifth coil
80, 80G: temperature detection sensor 81, 81G: first temperature detection sensor
82, 83G: second temperature detection sensor 83: third temperature detection sensor
D1: direction of rotation axis D2: opposite direction
IW1, IW2: inner width OW1, OW2: outer width
T1: direction of rotation

Claims (20)

Rotatable heating element;
And a coil unit circuit that generates magnetic flux for heating the heating element, and includes a coil unit disposed to be spaced apart from an outer circumferential surface of the heating element in an opposite direction and a power supply unit supplying power to the coil unit; and
The coil part,
A first coil disposed along the width direction of the heating element;
A pair of second coils disposed to overlap in the opposite direction on both ends of the first coil in the width direction; And
And a third coil disposed to overlap in the opposite direction at a central portion of the first coil in the width direction,
In the coil unit circuit, the current direction of the first coil and the third coil is the same direction, and the current direction of the second coil is the same direction as that of the first coil and the third coil, and the opposite direction. A fixing device comprising a switching connection portion for switching the series connection type of the first coil, the second coil, and the third coil so as to be in one direction. The method of claim 1,
A fixing device in which the number of turns of the second coil is less than that of the first coil. The method of claim 1,
In the rotation direction of the heating element, an inner width of the second coil and the third coil is greater than an inner width of the first coil, and an outer width of the second coil and the third coil is smaller than an outer width of the first coil . The method of claim 1,
The fixing device of the second coil and the third coil has the same separation distance from the heating element in the opposite direction and the number of turns. The method of claim 1,
The second coil and the third coil,
A structure in which the ends in the width direction are disposed adjacent to each other, and a structure in which the ends in the width direction are disposed to be spaced apart from each other, and the distance from the heating element in the opposite direction is different from each other, and the ends in the width direction are in the opposite direction A fixing device disposed in any one of the structures disposed to be overlapped. The method of claim 1,
The first coil, the second coil, and the magnetic flux generated by the third coil are concentrated on the heating element, and further comprising a core portion having a plurality of cores, and
The fixing device is disposed at a position where the core portion overlaps at least the second coil and the third coil in the width direction. The method of claim 6,
The first coil is disposed closer to the core portion than the second coil and the third coil in the opposite direction. The method of claim 6,
The core part,
A connection portion overlapping in the opposite direction with a connection region extending from the second coil-side end of the third coil to the third coil-side end of the second coil; And
In addition to the connection part, a main part overlapping the coil part; and,
The connection part and the main part,
Any one of a structure in which the plurality of cores have different arrangement densities and the same magnetic permeability, a structure in which the plurality of cores have different magnetic permeability, and a structure in which the distances in the opposite direction from the heating element of the plurality of cores are different A fixing device having a. The method of claim 1,
A fixing device in which a ratio of the magnetic flux generated by the second coil and the third coil to the magnetic flux generated by the first coil is 50% or less. The method of claim 1,
The coil part,
A pair of fourth coils disposed to overlap with both ends in the width direction of the first coil and the second coil in the opposite direction; And
A fifth coil disposed to overlap the central portion in the width direction of the first coil and the third coil in the opposite direction; and
The ratio of the width direction length of the fourth coil and the fifth coil is different from the ratio of the width direction length of the second coil and the third coil,
The switching connection unit connects the first coil, the second coil, the third coil, the fourth coil and the fifth coil in series, and at the same time, the first coil, the third coil, and the fifth coil The first coil and the second coil so that the current direction of is the same direction and the direction of the current of the second coil and the fourth coil is one of the same direction and the opposite direction to the direction of the current of the first coil. And a fixing device for switching a series connection type of the third coil, the fourth coil, and the fifth coil. The method of claim 10,
A fixing device in which a ratio of the magnetic flux generated by the fourth coil and the fifth coil to the magnetic flux generated by the first coil is 50% or less. The method of claim 1,
The coil unit circuit further includes a control unit for controlling at least one of the power supply unit and the switching connection unit,
The control unit individually sets at least one control pattern of the power supply unit and the switching connection unit at the time of preparation for feeding, at the start of feeding, at the time of continuous feeding, and at the end of feeding. The method of claim 12,
The control pattern includes a pattern for setting the supply and stop of power by the power supply unit. The method of claim 12,
The control pattern includes a pattern for setting a series connection type of the coil unit by the switching connection unit. The method of claim 12,
The control unit is a fixing device having a plurality of the control patterns. The method of claim 15,
The control unit,
A fixing device for determining the control pattern according to at least one of a width of a recording medium, a thickness of a recording medium, and a difference between a measured temperature of the heating element and a target temperature. The method of claim 1,
A first temperature detection sensor configured to detect a temperature of a region of the heating element that overlaps a central portion of the first coil and the third coil in the width direction and the opposite direction; And
A pair of second temperature detection sensors configured to detect a temperature of a region in which the first coil and the second coil overlap each other in the opposite direction and a region overlapped in the opposite direction, among the regions of the heating element; Fixing device. The method of claim 17,
The coil part,
A pair of fourth coils disposed to overlap with both ends in the width direction of the first coil and the second coil in the opposite direction;
A fifth coil disposed to overlap the central portion in the width direction of the first coil and the third coil in the opposite direction; and
The fifth coil is disposed to overlap an end portion of the second coil on the third coil side in the opposite direction,
The fixing device,
A pair of third temperature detection sensors for detecting a temperature of a region where the second coil and the fifth coil overlap each other and a region overlapping each other in the opposite direction among the regions of the heating element; and
The first temperature detection sensor detects a temperature of a region of the heat generating element overlapping the central portion of the first coil, the third coil, and the fifth coil in the width direction and the opposite direction,
The second temperature detection sensor detects a temperature of a region of the heating element, a region where the first coil, the second coil, and the fifth coil overlap each other and a region overlapping in the opposite direction. The method of claim 18,
When feeding a first recording medium, a second recording medium wider than the first recording medium, and a third recording medium wider than the second recording medium,
The length of the first coil in the width direction is greater than the width of the third recording medium,
The length in the width direction of the third coil is smaller than the width of the second recording medium and larger than the width of the first recording medium,
A fixing device in which a length of the fifth coil in the width direction is smaller than a width of the third recording medium and larger than a width of the second recording medium. An image forming apparatus comprising the fixing device according to any one of claims 1 to 19.

Images