KR20160051500A - Induction heating type fusing device and image forming apparatus using the same - Google Patents

Abstract

The present invention relates to an induction heating fusing device and an image forming apparatus, which can improve uniformity of temperature distribution of a heating element. The disclosed fusing device comprises: a rotatable heating element; and a coil unit circuit which generates magnetic flux to heat the heating element. The coil unit circuit includes a coil unit spaced apart from an outer circumferential surface of the heating element in an opposite direction, and a power supply unit configured to supply power to the coil unit. The coil unit includes a first coil arranged along a widthwise direction of the heating element, a pair of second coils disposed in both end portions of the first coil in the widthwise direction to overlap the first coil in an opposite direction, and a third coil disposed in a center portion of the first coil in the widthwise direction to overlap the first coil in an opposite direction. The coil unit circuit includes a switch connection unit which switches a series connection form of the first, second, and third coils to switch current directions of the first, second, and third coils.

Description

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

A fixing apparatus and an image forming apparatus employing an induction heating system are disclosed.

As an image fixing apparatus for an image forming apparatus, for example, an induction heating fixing apparatus disclosed in Patent Document 1 is known.

(Patent Document 1) US 2013-0078019 A

The induction heating fixing apparatus disclosed in Patent Document 1 has a first coil capable of heating a heating element up to the maximum paper width that can be fed and a second coil disposed so as to overlap the first coil at both end portions in the width direction of the first coil. The induction heating fixing apparatus further includes a power supply for supplying electric power to the first coil and the second coil and a switch for controlling the directions of currents flowing through the first coil and the second coil to be the same or opposite directions.

When passing the wide-width paper (paper superimposed on the second coil) to the above-described fixing device, currents in the same direction are supplied to the first coil and the second coil. When a narrow sheet of paper (a sheet that does not overlap with the second coil) is passed, a current in the opposite direction is supplied to the first coil and the second coil. Thus, it is possible to suppress the generation of magnetic flux in a portion where the sheet of the heating element does not pass (non-paper feeding portion) when the narrow paper is passed, and the temperature rise of the non-paper feeding portion can be suppressed.

If the temperature distribution of the heating element of the fixing device is not uniform, the image may be affected. For example, if the temperature distribution of the heating element is not uniform, the gloss of the printed image may become uneven. Further, unnecessary energy (power) is consumed in the induction heating fixing apparatus if the temperature of a part of the region of the heating element becomes higher than the temperature required for fixing.

An object of the present invention is to provide an induction heating fixing apparatus and an image forming apparatus which can equalize the temperature distribution of a heating element.

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

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

Wherein the coil unit circuit includes a switching connection portion for switching a serial connection form 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 Respectively.

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

The inner width of the second coil and the third coil may be larger than the inner width of the first coil in the rotating direction of the heating element and the outer width of the second coil and the third coil may be smaller than the outer width of the first coil .

The distance between the second coil and the third coil in the opposite direction from the heating element, and the number of turns may be the same.

Wherein the second coil and the third coil have a structure in which the end portions in the width direction are disposed adjacent to each other and a structure in which the end portions in the width direction are spaced apart from each other and a structure in which the distance from the heat generating element in the opposite direction is And the end portions in the width direction overlap each other in the opposite direction.

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

The first coil may be disposed at a position closer to the core portion than the second coil and the third coil in the opposing direction.

Wherein the core portion has a connection portion extending from the second coil-side end portion of the third coil to the third coil-side end portion of the second coil and overlapping the connection region in the opposite direction; And a main portion overlapping with the coil portion in addition to the connection portion, wherein the connection portion and the main portion have a structure in which the plurality of cores have different arrangement densities and the same permeability, and a structure in which the plurality of cores have different magnetic permeabilities Structure and a structure in which the distance in the opposite direction from the heating element of the plurality of cores are different from each other.

The 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 portion includes a pair of fourth coils arranged to overlap with the widthwise opposite ends of the first coil and the second coil in the opposite direction; And a fifth coil disposed so as to overlap the first coil and the third coil in the width direction center portion and in the opposite direction, and the fourth coil and the fifth coil may have a width direction length The ratio is different from the ratio of the lengths of the second coil and the third coil in the width direction, and the switch connection portion has the first coil, the second coil, the third coil, the fourth coil, The first coil, the second coil, the third coil, the fourth coil, and the fifth coil are switched so that the current direction of the first coil, the second coil, the third coil, the fourth coil, , The fourth coil and the fifth coil can be switched in series.

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. The control unit controls the power supply unit, the power supply unit, The control pattern of 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 the supply and stop of power by the power supply unit.

The control pattern may include a pattern for setting a serial connection form of the coil portion by the switching connection portion.

The control unit may have a plurality of 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 the measurement temperature of the heating element and the target temperature.

Wherein the fixing device includes a first temperature detecting sensor for detecting a temperature of a region of the heating element which overlaps with the center portion in the width direction of the first coil and the third coil in the opposite direction; And a pair of second temperature detection sensors for detecting a temperature of a region of the heating element where the first coil and the second coil overlap with each other in the opposing direction and a region overlapping with the opposing direction can do.

The coil portion includes a pair of fourth coils arranged to overlap with the widthwise opposite ends of the first coil and the second coil in the opposite direction; And a fifth coil disposed to overlap the first coil and the third coil in the width direction central portion and in the opposite direction. And the fifth coil may be arranged to overlap with the third coil side end of the second coil in the opposite direction. Wherein the fixing device further comprises a pair of third temperature detection sensors for detecting a temperature of a region of the heating element where the second coil and the fifth coil overlap with each other and a region overlapping in the opposite direction , The first temperature detecting sensor detects the temperature of a region of the first coil, the third coil, and the fifth coil overlapping with the widthwise center portion in the opposite direction, of the region of the heating element, 2 temperature detecting sensor can detect a temperature of a region of the heating element where the first coil, the second coil, and the fifth coil overlap each other and a region overlapping in the opposite direction.

When a first recording medium, a second recording medium that is wider than the first recording medium, and a third recording medium that is wider than the second recording medium are fed, the length of the first coil in the width direction The width of the third coil in the width direction is smaller than the width of the second recording medium and is larger than the width of the first recording medium and the length of the fifth coil in the width direction is larger than the width of the third recording medium, May be smaller than the width of the third recording medium and larger than the width of the second recording medium.

The image forming apparatus according to one aspect includes the above-described fixing device.

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

1 is a schematic configuration diagram of an image forming apparatus according to the first embodiment.
2 is a schematic view showing a fixing device of the image forming apparatus of FIG.
3 is a perspective view showing the fixing device of Fig.
Fig. 4 is a plan view of the coil and core portion according to the fixing device of Fig. 3;
FIG. 5 is a plan view of the first coil and the core of FIG. 4; FIG.
Fig. 6 is a circuit diagram (Fig. 6 (a)) of the coil unit in the first series connection mode and Fig. 6 (b) showing the temperature distribution of the heat generating rotating body.
Fig. 7 is a diagram showing a coil unit circuit diagram (Fig. 7 (a)) and a temperature distribution of the heat generating rotating body in the second series connection mode (Fig. 7 (b)).
8 is a circuit diagram of a coil unit and a temperature distribution of a heat generating rotating body according to a comparative example.
9 is a diagram comparing the temperature distribution of the heat generating rotating body according to the first embodiment and the temperature distribution of the heat generating rotating body according to the comparative example.
10 is a view showing the coil configuration and the temperature distribution of a heating element of the fixing device according to the second embodiment.
11 (a)). Fig. 11 shows a case where a sheet having a width large enough to come in contact with a portion opposed to the fourth coil of the heat generating rotating body is fed 11 (b)). In the case where a sheet that does not reach the portion facing the second coil of the heat generating rotating body is fed (Fig. 11 (c) ) Coil unit circuit diagrams.
Fig. 12 shows a state in which a current flows in the coil in the connection region in the third embodiment (Fig. 12 (a)), a state in which current flows in the coil in the connection region in the fourth embodiment (Fig. 12 (c)) in which a current flows in the coil in the connection region of the shape shown in Fig.
Fig. 13 is a diagram showing the magnetic flux distribution (Fig. 13 (a)) of the heat generating rotary body in the third embodiment and the magnetic flux distribution (Fig. 13 (b)) of the heat generating rotary body in the fourth embodiment.
14 is a perspective view showing a fixing device according to the third embodiment.
Fig. 15 is a plan view of a coil and a core according to the fixing device of Fig. 14; Fig.
16 is a perspective view showing a fixing device according to a modification.
17 is a view showing the magnetic flux distribution of the heat generating rotating body in the fifth embodiment.
Fig. 18 is a perspective view (Fig. 18 (a)) showing a fixing apparatus according to a modification, and a plan view (Fig.
Fig. 19 is a view showing a current flowing in a coil in the fixing apparatus according to the sixth embodiment. Fig.
20 is a diagram showing the temperature distribution of the heat generating rotating body when a current is passed as shown in Fig.
21 is a diagram showing a control pattern.
22 is a table showing the relationship between various conditions and the control pattern of FIG.
23 is a view showing a control pattern of the fixing device according to the seventh embodiment.
24 is a view showing a control pattern of the fixing device according to the seventh embodiment.
25 is a table showing the relationship between various conditions and the control patterns of Figs. 23 and 24. Fig.
26 is a schematic view showing a temperature detection sensor of a fixing apparatus according to the eighth embodiment.
27 is a diagram showing the temperature distribution of the heating element with respect to each paper size.
28 is a schematic diagram showing a temperature detection sensor of a fixing apparatus according to the ninth embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or equivalent portions are denoted by the same reference numerals, and redundant description is omitted.

[First Embodiment]

(Overall Configuration of Image Forming Apparatus)

1, the image forming apparatus 1 includes a transfer unit 10, a transfer unit 20, a photoconductive drum 30, four developing units 100, and a fixing device 40 . The image forming apparatus 1 is, for example, an image forming apparatus using an electrophotography technique.

The transfer unit 10 receives the paper P (media) as a recording medium on which an image is finally formed and transfers the paper P onto the recording medium conveying path. The paper P is stacked in the cassette C. The transfer unit 10 reaches the secondary transfer region R in accordance with the timing at which the toner image to be transferred onto the paper P reaches the secondary transfer region R. [

The transfer unit 20 conveys the toner image formed by the four developing units 100 to the secondary transfer region R for secondary transfer onto the paper P. [ The transfer unit 20 may include a transfer belt 21, suspension rollers 21a, 21b, 21c and 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 intervenes between the transfer belt 21 and the photosensitive drum 30. The secondary transfer roller 24 interposes the transfer belt 21 between the secondary transfer roller 24 and the suspension roller 21d.

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

The photosensitive drum 30 is a drum-shaped latent electrostatic image bearing member on which an image is formed on the outer peripheral 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, for example, four photosensitive drums 30 are provided along the moving direction of the transfer belt 21 corresponding to each color of magenta, yellow, cyan, and black. Each photosensitive 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.

A charging voltage is applied to the charging roller 32, whereby the surface of the photoconductor drum 30 is uniformly charged to a predetermined potential. The charging roller 32 is provided in proximity to or in contact with the photosensitive drum 30, and performs the above-described uniform charging using a micro gap (GAP) discharge. The exposure unit 34 exposes the surface of the photosensitive drum 30 charged by the charging roller 32 according to image information to be formed on the paper P. [ As a result, the potential of the exposed portion of the surface of the photosensitive drum 30 exposed by the exposure unit 34 is changed to form an electrostatic latent image. The four developing units 100 develop the electrostatic latent image as the developing voltage is applied. More specifically, each developing unit 100 develops the electrostatic latent image drawn on the photosensitive drum 30 using the toner supplied from the toner tank 36 to generate a toner image. Magenta, yellow, cyan, and black toners are filled in the four toner tanks 36, respectively.

The cleaning unit 38 recovers the toner (residual toner) remaining on the photosensitive drum 30 even after it has been temporarily transferred to the transfer belt 21. The cleaning unit 38 may include, for example, a cleaning blade, and removes the residual toner by bringing the cleaning blade into contact with the outer peripheral surface of the photoconductor drum 30. The cleaning unit 38 may include a charge eliminating lamp 39 which is positioned close to the outer periphery of the photoconductor drum 30 and controls the surface potential of the photoconductor drum 30. The antistatic lamp 39 is an erase lamp that discharges the surface of the photosensitive drum 30 by lighting. The erasing lamp 39 is operated at the time of image formation (printing) to set the surface potential of the photoconductor drum 30 to a desired value. The charge eliminating lamp 39 is operated at the time of non-image forming after the transfer, and the residual electric charge of the photosensitive drum 30 is made lower than the light attenuation voltage of the photosensitive drum 30 to reset the surface potential. The antistatic lamp 39 suppresses the unstable charging potential due to the residual electric charge and the generation of ghost in the image. In addition, at the time of non-image formation, not only before and after the print operation but also between pages when image formation is performed over a plurality of pages is included.

The fixing device 40 may include a pressure rotating body 42 and a heat generating rotating body 44. The fixing device 40 fixes the toner image secondaryly transferred from the transfer belt 21 to the paper P by attaching it to the paper P. The details of the fixing device 40 will be described later.

The image forming apparatus 1 is also 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 inputted to the image forming apparatus 1, the control unit of the image forming apparatus 1 uniformly charges the surface of the photoconductive drum 30 at a predetermined potential by using the charging roller 32 And the exposure unit 34 to irradiate the surface of the photoconductor drum 30 with modulated laser light corresponding to an image signal to form an electrostatic latent image.

On the other hand, in the developing unit 100, the developer of the two-component developing system is carried on the developing roller 110. The developer includes a toner and a carrier. The developing unit 100 mixes the toner and the carrier with stirring to sufficiently charge the toner. When the developer is conveyed to the area opposed to the photoconductive drum 30 by the rotation of the developing roller 110, the toner in the developer is transferred to the electrostatic latent image formed on the outer peripheral surface of the photoconductive drum 30. [ As a result, the electrostatic latent image is developed. The thus formed toner image is primarily transferred from the photoconductor drum 30 to the transfer belt 21 in the area where the photoconductor drum 30 and the transfer belt 21 are opposed to each other. Toner images formed on the four photosensitive drums 30 are sequentially stacked on the transfer belt 21 to form one laminated toner image. The stacked toner image is secondarily transferred to the paper P transferred from the transfer unit 10 in the secondary transfer region R where the suspension roller 21d and the secondary transfer roller 24 are opposed to each other.

The paper P onto which the laminated toner images are secondarily transferred is conveyed to the fixing device 40. [ When the paper P is passed between the heat generating rotating body 44 and the pressing rotating body 42 while applying heat and pressure, the laminated toner image is fused to the paper P. Thereafter, the paper P is discharged to the outside of the image forming apparatus 1 by the discharge rollers 52 and 54. Further, in the case where the transfer unit 20 is provided with a belt cleaning device, the toner remaining on the transfer belt 21 after the laminated toner image is secondarily transferred onto the paper P can be removed by the belt cleaning device.

(Configuration of Fixing Device)

Next, a detailed configuration of the fixing device 40 will be described with reference to Fig. 2, the fixing device 40 is an induction heating fixing device including a pressure rotating body 42, a heat generating rotary body 44, and a magnetic field generating device 45. [ The magnetic field generator 45 is configured to concentrate the magnetic flux generated by the coil portion 46 and the coil portion 46 disposed on the outer peripheral surface 44a of the heat generating rotating body 44 to the heat generating rotating body 44 And a core portion 47 for forming a core.

The pressure rotating body 42 is a cylindrical rotating body provided so as to pressurize the heat generating rotating body 44, and may include, for example, silicone rubber having a hardness of JISA of 65 degrees. The surface of the pressure rotating body 42 may be coated with a fluororesin or the like in order to improve abrasion resistance and releasability. The pressure rotating body 42 may also include a foam of the so-called sponge type. Further, the pressure rotating body 42 may include a material having a low thermal conductivity in order to prevent the diffusion of heat. The axial length of the pressure rotating body 42 is, for example, 210 to 370 mm, and the outside diameter thereof is, for example, 20 to 100 mm.

The heat generating rotary body 44 may be a multi-layer structure including a metal conductor, which is a magnetic material such as nickel, chrome, copper, or the like, as a cylindrical rotating body (rotatable heating body) having a heat generating layer. The surface of the heat generating rotating body 44 may be coated with a fluororesin or the like in order to improve abrasion resistance and releasability. In this case, the layered heat generating rotating body 44 may include a heating layer of 10 to 50 mu m, a rubber layer of 50 to 500 mu m, and a fluororesin layer of 10 to 50 mu m. The length of the heat generating rotating body 44 in the axial direction is, for example, 210 to 370 mm, and the outside diameter thereof is, for example, 20 to 100 mm.

The heat generating rotary body 44 generates heat under the influence of the magnetic flux generated in the coil portion 46. That is, the magnetic flux generated in the coil portion 46 is guided to the outer circumferential surface 44a of the heat generating rotating body 44 by the core portion 47. Then, the magnetic flux generates an eddy current, and Joule's heat is generated on the outer circumferential surface 44a of the heat generating rotating body 44, so that the heat generating rotating body 44 generates heat. The surface temperature of the heat generating rotating body 44 during a predetermined fixing operation is, for example, 140 to 200 占 폚.

On the inner circumferential surface side of the heat generating rotating body 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 heat generating rotary body 44. [ The nip forming member 44b presses the heat generating rotary body 44 from the inner circumferential surface side of the heat generating rotary body 44 toward the pressing rotary body 42 side. The heating rotary body 44 is rotated in one direction (rotation direction T1) by a drive motor (not shown), and the pressure rotary body 42 is rotated in the rotational direction T1 (T2). The pressure rotating body 42 and the heat generating rotating body 44 melt-fix the toner image on the sheet by passing the sheet through the fixing nip portion N which is a contact area of the pressing rotating body 42 and the heat generating rotating body 44.

The coil portion 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 portion 46 may be, for example, 20 kHz to 100 kHz. The coil portion 46 is disposed on the opposite side of the pressure rotating body 42 with respect to the heat generating rotary body 44 and can be arranged to cover approximately half of the outer periphery of the heat generating rotary body 44. The coil portion 46 is not brought into contact with the heat generating rotary body 44 but is disposed at a position close to the outer peripheral surface 44a. The distance between the coil portion 46 and the heat generating rotary body 44 may be, for example, 1 to 10 mm. The coil portion 46 extends between approximately both ends of the heat generating rotary body 44 in the direction of the rotation axis of the heat generating rotary body 44 (the width direction of the heat generating rotary body 44).

The core portion 47 is a magnetic core disposed to cover the coil portion 46 and forming a magnetic path of magnetic flux generated in the coil portion 46. The core portion 47 receives the magnetic flux so as to prevent the magnetic flux generated in the coil portion 46 from leaking, and guides the magnetic flux to the heat generating rotary body 44. The core portion 47 is disposed on the opposite side of the heat generating rotary body 44 with respect to the coil portion 46 as a reference. The core portion 47 is not in contact with the coil portion 46 but is disposed at a close position, and the distance from the coil portion 46 may be, for example, 1 to 10 mm. The core portion 47 may also be formed of a high permeability, low loss magnetic material, such as ferrite.

Next, the details of the coil portion 46 and the core portion 47 will be described with reference to Figs. 3 to 5. Fig. 3 to 5, the coil portion 46 is a race track type (semicircular) coil and extends in the rotation axis direction D1 and the rotation direction T1. The coil section 46 includes a pair of rectilinear sections 46a and 46b extending in the direction of the axis of rotation D1 and arranged in parallel with each other in the rotation direction T1 and a pair of rectilinear sections 46a and 46b, And a pair of circular arc portions 46c and 46c extending in the rotation direction T1. The coil lines of the coil portion 46 are arranged in parallel in the rotation axis direction D1 and the rotation direction T1 in order to reduce the thickness.

The coil portion 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. The length of the first coil 48 may be the same as that of the heat generating rotary body 44 or may be slightly longer than the heat generating rotary body 44 in the direction of the rotation axis D1. The first coil 48 is arranged in an overlapping direction with the substantially entire region of the heat generating rotary body 44 in the direction of the rotation axis D1 in the opposite direction (Fig. 2: D2). The second coil 49 may be shorter than the half length of the heat generating rotary body 44 in the direction of the rotation axis D1. The second coil 49 is disposed in the opposite direction D2 so as to overlap the both ends 48x of the first coil 48 in the rotational axis direction D1. The third coil 50 is arranged in the opposite direction D2 to the central portion 48y of the first coil 48 in the direction of the axis of rotation D1. The first coil 48, the second coil 49 and the third coil 50 each have a pair of linear portions 46a and 46b and a pair of circular arc portions 46c and 46c.

The distance from the outer circumferential surface 44a of the heat generating rotary body 44 to the second coil 49 and the third coil 50 is shorter than the distance from the outer peripheral surface 44a of the heat generating rotary body 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 heat generating rotary body 44 than the first coil 48.

The second coil 49 and the third coil 50 may have the same distance from the heat generating rotary body 44 in the opposite direction D2. The third coil 50 is disposed in a region other than 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). The arc portion 46c on the third coil 50 side is disposed adjacent to the arc portion 46c of the third coil 50 in the direction of the rotation axis D1 of the second coil 49. [ The connection 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 an area from the arc portion 46c, which is the end of the second coil 49 on the third coil 50 side, to the arc portion 46c, which is the end of the third coil. That is, the arc portion 46c of the second coil 49 and the arc portion 46c of the third coil 50 are included in the connection region 46x. The length obtained by adding the length of the pair of second coils 49 in the rotation axis direction D1 and the length of the rotation axis direction D1 of the third coil 50 is equal to the length of the rotation axis direction D1 of the first coil 48 . ≪ / RTI > The position of the arc portion 46c which is the end opposite to the third coil 50 of the pair of second coils 49 in the direction of the axis of rotation D1 is the position of the arc portion 46c ) In the first embodiment.

The number of turns of the second coil 49 and the number of turns of the third coil 50 may be equal to each other 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 windings of the second coil 49 and the third coil 50 may be 10% or more and 50% or less of the number of windings of the first coil 48. For example, % ≪ / RTI > Each coil line of the first coil 48, the second coil 49 and the third coil 50 may have a twisted number of 0.08 to 0.8 mm (for example, 0.1 to 0.3 mm) And a litz wire of 1 to 200 (e.g., 20 to 150). Each coil line of the second coil 49 and the third coil 50 may have the same line diameter and twist number.

The inner width IW1 of the second coil 49 and the third coil 50 in the rotating direction T1 of the heat generating rotating body 44 is set such that the inner width IW1 of the first coil 48 in the rotating direction T1 The outer width OW1 of the second coil 49 and the third coil 50 in the rotation direction T1 is larger than the outer width OW1 of the first coil 48 in the rotation direction T1 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 regular intervals in the direction of the rotation axis D1 of the heat generating rotary body 44 so as to overlap with the linear portions 46a and 46b in the opposite direction D2. The plurality of cores (51) are disposed at positions overlapping 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. The permeability of the plurality of cores 51 and the distance from the coil portion 46 may be equal to each other. 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, the power supply to the coil portion 46 will be described with reference to Figs. 6 and 7. Fig. 6 and 7, the position of the second coil 49 and the third coil 50 in the opposite direction D2 is shown for the sake of convenience. The coil unit circuit (61) generates a magnetic flux for heating the heating element (44). The coil unit circuit 61 includes a coil portion 46, a power supply portion 62, and a circuit portion 63. The coil part 46 is included in the coil unit circuit 61 and is supplied with electric power. The power supply unit 62 includes an inverter that supplies electric power to the coil part 46. [ The circuit portion 63 connects the coil portion 46 and the power supply portion 62. The circuit portion 63 has a switch connection portion 64. [ The switching connection section 64 connects the first coil 48, the second coil 49 and the third coil 50 in series and switches the serial connection form of each coil so that the current direction of each coil is switched do. The switch connection portion 64 is a switch disposed between the first coil 48 and the second coil 49 and is configured to switch between the current direction of the first coil 48 and the third coil 50 and the current direction of the second coil 49 The current direction is switched to the same direction or the opposite direction. The current directions of the first coil 48 and the third coil 50 are always the same direction.

Specifically, the switching connection portion 64 is switched to two direct connection types (a first series connection type and a second series connection type). In the first series connection mode, 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 direction The coils are connected in series. The magnetic flux density at the outer circumferential surface 44a of the heat generating rotating body 44 is smaller than the magnetic flux density at the outer circumferential surface 44a of the second coil 49 and the third coil 50 in the rotational axis direction (D1). As a result, as shown in Fig. 6 (b), the temperature at the outer circumferential surface 44a of the heat generating rotating body 44 becomes substantially constant in the rotation axis direction D1. This first series connection mode is selected when the width of the paper to be fed is relatively wide. The relatively large width paper refers to a paper having a width large enough to contact a portion (both end portions 44x) of the heat generating rotating body 44 opposed to the second coil 49, for example. Hereinafter, a relatively wide paper will be described as the first paper.

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 to each other in the second series connection mode So that each coil is connected in series. The current direction of the second coil 49 is opposite to the current direction of the first coil 48 and the third coil 50 so that a part of the magnetic flux of the first coil 48 is applied to the magnetic flux of the second coil 49 . Therefore, the magnetic flux density of the outer circumferential surface 44a of the heat generating rotating body 44 becomes lower at the opposite end portions 44x opposite to the second coil 49 than other portions. As a result, as shown in Fig. 7 (b), the temperature of the outer circumferential surface 44a of the heat generating rotating body 44 becomes lower at the both end portions 44x than other portions. This second serial connection type is selected when the width of the paper to be fed is relatively narrow. The paper having a relatively narrow width is, for example, a paper sheet having a narrow width so as not to reach the both end portions 44x of the heat generating rotating body 44. Hereinafter, a paper having a relatively narrow width will be described as a second paper.

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

The fixing device 40 may also be configured such that 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). Concretely, at least one of the output power of the power supply unit 62, the conditions of the second coil 49 and the third coil 50, and the condition of the core unit 47 can be adjusted.

The output power of the power supply unit 62 becomes higher as 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 Quot; magnetic flux ratio ") is high, for example, 300 to 2000W. The conditions of the second coil 49 and the third coil 50 are concretely the resonance frequency of the second coil 49 and the third coil 50, the material, the diameter, the number of twists, the rotation direction T1 (Or outer width), and the shape, etc. The higher the resonance frequency is, the lower the ratio of the magnetic flux is, for example, 10 to 100 kHz. In this case, the ratio of the magnetic flux can be set to 3% to 50%. As the material has a higher specific magnetic permeability, the ratio of the magnetic flux increases. 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 diameter of the wire (more specifically, the diameter of the wire) is, the higher the ratio of the magnetic flux is, for example, 0.08 to 0.8 mm, and 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 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 is, the lower the magnetic flux ratio is, 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 is, the higher the magnetic flux ratio is, 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, the winding shape of the twisted wire or the winding method of the twisted wire. When the winding shape of the twisted wire is U-shaped, the ratio of the magnetic flux increases, and may be, for example, a U-shape, a C-shape, or a semicircular shape. In addition, the winding method of the twisted wire becomes higher as the density becomes higher, for example, it may be a dense winding method or a winding method with intervals.

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

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

The fixing device 140 according to the comparative example shown in Fig. 8 includes the coil unit circuit 161 in the same manner as the fixing device 40 according to the first embodiment. The coil unit circuit 161 includes a coil portion 146, a power supply portion 162, and a circuit portion 163. The coil portion 146 is composed of a first coil 148 disposed along the rotational axis direction D1 and a second coil 148 disposed on both ends 148x of the first coil 148 in the rotational axis direction D1, And a pair of second coils 149 arranged. On the other hand, the coil portion 146 is provided with a coil (a coil corresponding to the third coil 50 of the fixing device 40) which is superimposed on the central portion 148y of the first coil 148 in the rotational axis direction D1 I never do that. The circuit portion 163 has a switching connection portion 164 for switching the serial connection form of each coil so that the current direction of each coil is switched.

In the coil unit circuit 161, the switching connection section 164 switches between two serial connection types. 8A, the respective coils are connected in series so that the current direction of the first coil 148 and the current direction of the second coil 149 are in the same direction, as shown in Fig. 8A. This serial connection type is selected when the width of the paper to be fed is relatively wide. In each of the series connection modes, the coils are connected in series so that the current direction of the first coil 148 and the current direction of the second coil 149 are opposite to each other, 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, a part of the magnetic flux of the first coil 148 is erased in the magnetic flux of the second coil 149 by the series connection of FIG. 8 (b). Accordingly, the magnetic flux density of the outer circumferential surface 44a of the heat generating rotating body 44 becomes lower than the other portions at both end portions 44x. As a result, it is possible to suppress the temperature rise of the portion (non-paper feeding portion) of the heat generating rotating body 44 through which the paper does not pass (see Fig. 8 (b)).

8 (a), the magnetic flux density of the both end portions 44x, which is a portion of the heat generating rotating body 44 opposed to the second coil 149, is higher than that of the central portion 44y Which is higher than the magnetic flux density. Therefore, the temperature rise of the heat generating rotating body 44 at the both end portions 44x is larger than the central portion 44y of the rotation axis direction D1 (see Fig. 8 (a)). As a result, if the temperature of the heat generating rotary body 44 is controlled so as to be settable at the central portion 44y of the heat generating rotating body 44, the temperature of the both end portions 44x of the heat generating rotating body 44 becomes relatively high The temperature distribution of the heating rotator 44 becomes uneven. If the temperature distribution of the heat generating rotating body 44 is not uniform, there is a possibility that the influence (gloss difference, etc.) on the image may be reduced. Further, since the temperature of both end portions 44x of the heat generating rotating body 44 becomes 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, the first coil 48 and the second coil 48 overlap each other at both ends 48x of the first coil 48 facing the both ends 44x of the heat- A pair of second coils 49 are provided. The third coil 50 is provided so as to overlap the central portion 48y of the first coil 48 opposed to the central portion 44y of the heat generating rotating body 44. The series connection mode of each coil is switched so that the current directions of the serially connected coils are switched. (See FIG. 7) is selected and the current direction of the second coil 149 is selected for the first coil 148 and the third coil 150 The opposite direction. In this case, as in the comparative example, the generation of magnetic flux in the non-paper feeding portion of the heating rotator 44 is suppressed, and the temperature rise of the non-paper feeding portion can be suppressed. 6) is selected and the first coil 48, the second coil 49, and the current of the third coil 50 (see FIG. 6) are selected when the relatively wide first paper passes, The directions are the same direction. In this case, the magnetic flux generated by the third coil 50 is also generated in the central portion 44y where the second coil 49 is not provided. As a result, it is possible to suppress the increase in the temperature rise of the both end portions 44x relative to the central portion 44y of the heat generating rotating body 44. As described above, according to the fixing device 40, the temperature distribution of the heat generating rotary body 44 can be made uniform.

Thus, the temperature distribution of the heat generating rotary body 44 can be made uniform, and the gloss difference of the image can be suppressed. In addition, energy (power) consumption in the fixing device 40 can also be reduced. For example, when the second sheet is fed, the temperature of the central portion 44y of the heat generating rotating body 44 may be maintained at 150 占 폚. In this case, as shown in Fig. 9, in the comparative example, the temperature of the both end portions 44x of the heat generating rotating body 44 becomes higher than the temperature of the central portion 44y (one-dot chain line in Fig. 9) The temperature of both end portions 44x of the heat generating rotating body 44 becomes equal to the temperature of the center portion 44y (solid line in Fig. 9). In the comparative example, a large amount of electric power (for example, 780 W) is required as the temperatures of the both end portions 44x are increased. On the other hand, in the fixing device 40, since the heat generating rotary body 44 is uniformly heated, can do.

In the fixing device 40, the number of turns of the second coil 49 is less than the number of turns of the first coil 48. Specifically, the number of windings of the second coil 49 is not less than 10% and not more than 50% (for example, not more than 30%) of the number of windings of the first coil 48. Accordingly, the magnetic flux density of the magnetic field generated by the second coil 49 is reduced, so that it is possible to effectively prevent the temperature rise of the both end portions 44x from being increased as compared with the central portion 44y of the heat generating rotating body 44. [

The inner width IW1 of the second coil 49 and the third coil 50 in the rotating direction T1 of the heat generating rotating body 44 is set such that the inner width IW1 of the first coil 48 in the rotating direction T1 The outer width OW1 of the second coil 49 and the third coil 50 in the rotation direction T1 is larger than the outer width OW2 of the first coil 48 in the rotation direction T1, Lt; / RTI > That is, the second coil 49 and the third coil 50 are disposed inside the first coil 48 in the rotation direction T1. This makes it possible to prevent the magnetic fluxes of the second coil 49 and the third coil 50 from being generated in the region where the influence of the magnetic flux of the first coil 48 does not occur, The distribution can be made uniform.

The distance between the second coil 49 and the third coil 50 in the opposite direction D2 from the heat generating rotating body 44 and the number of turns are the same. This makes it possible to make the magnetic fluxes generated by the second coil 49 and the third coil 50 equal to each other and to make the temperature distribution of the heat generating rotating body 44 more uniform.

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, The material of the second coil 49 and the resonance frequency of the third coil 50, the material, the diameter, the twist number, the width or the outer width, the shape, the shape of the core, The density of the core, and the density of the core are adjusted. By suppressing the magnetic flux density of the magnetic flux generated by the second coil 49 and the third coil 50 as described above, the heat generated by the second coil 49 or the third coil 50, The temperature distribution of the heat generating rotary body 44 can be uniformed.

[Second Embodiment]

Next, an image forming apparatus according to a second embodiment will be described with reference to Fig. 10 in addition to Fig. 1 to Fig. Further, in each of the following embodiments including the present embodiment, the differences from the first embodiment will be mainly described, and redundant description will be omitted.

The image forming apparatus 1A includes a fixing device 40A. The fixing device 40A has a coil portion 46A. The coil portion 46A is connected to each of the coils (the first coil 48, the second coil 49 and the third coil 50) included in the coil portion 46 of the first embodiment, 71A and a fifth coil 72A.

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

The fourth coil 71A and the fifth coil 72A may have the same distance from the heat generating rotary body 44 in the opposite direction D2. The distance from the outer peripheral surface 44a of the heat generating rotating body 44 to the fourth coil 71A and the fifth coil 72A is smaller 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 arranged such that their end portions are adjacent to each other.

The length obtained by adding the length of the pair of fourth coils 71A in the rotational axis direction D1 and the length of the rotational axis direction D1 of the fifth coil 72A is equal to the length of the pair of second coils 49 in the rotational axis direction D1 And the length of the direction of the rotation axis D1 of the third coil 50 is approximately equal to the 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. [ The end position of the pair of fourth coils 71A on the opposite side to the side adjacent to the fifth coil 72A is located at a side opposite to the side of the pair of second coils 49 adjacent to the third coil 50 And the rotation axis direction D1. The ratio of the length of the fourth coil 71A to the length of the fifth coil 72A in the direction of the rotation axis D1 is the length of the second coil 49 and the third coil 50 in the direction of the rotation axis D1 It 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 of the second coil 49 in the rotation axis direction D1. The length of the fifth coil 72A in the rotation axis direction D1 may be longer than the length of the third coil 50 in the rotation axis direction D1.

The fourth coil 71A and the fifth coil 72A are connected in series to the first coil 48, the second coil 49 and the third coil 50 by the switch connecting portion 64. [ The switching connection section 64 switches the serial connection form of the first coil 48, the second coil 49, the third coil 50, the fourth coil 71A and the fifth coil 72A. Further, the current directions of the first coil 48, the third coil 50, and the fifth coil 72A are always in the same direction. The current direction of each of the second coil 49 and the fourth coil 71A may be the same or opposite to the direction of the first coil 48. [

The fixing device 40A according to the second embodiment has the fourth coil 71A and the fifth coil 72A different in the ratio of the lengths from the ratio of the lengths of the second coil 49 and the third coil 50, . This makes it possible to equalize the temperature distribution of the heat generating rotating body 44 while coping with a finer difference in the paper size as compared with the fixing apparatus 40 according to the first embodiment.

In other words, a case will be considered in which a sheet of paper having a width large enough to come into contact with a portion of the heat generating rotating body 44 which faces the fourth coil 71A is fed. In this case, as shown in Fig. 11 (a), the current directions of all the coils are the same direction. Therefore, the magnetic flux density can be made substantially equal to the rotational axis direction D1, and the temperature distribution of the heat generating rotary body 44 can be made uniform. It is also conceivable that a sheet having a width large enough to come in contact with a portion opposed to the fourth coil 71A of the heat generating rotary body 44 but not to contact with the portion opposed to the second coil 49 is fed . In this case, as shown in Fig. 11 (b), only the current direction of the fourth coil 71A is opposite to the current direction of the other coils. Accordingly, when the sheet is fed, the generation of magnetic flux in the non-paper feeding section of the heat generating rotating body 44 is suppressed, and the temperature rise of the non-paper feeding section can be suppressed. It is also conceivable that a sheet that does not reach the portion of the heat generating rotating body 44 opposed to the second coil 49 is fed. In this case, as shown in Fig. 11 (c), the current direction of the second coil 49 in addition to the fourth coil 71A is opposite to the current direction of the other coils. Accordingly, when the sheet is fed, the generation of magnetic flux in the non-paper feeding section of the heat generating rotating body 44 is suppressed, and the temperature rise of the non-paper feeding section can be suppressed. 11, a part of the configuration of the fixing device 40A is omitted.

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 At least one of the output power of the power supply unit 62, the conditions of the fourth coil 71A and the fifth coil 72A and the condition of the core unit 47 can 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.

The conditions of the fourth coil 71A and the fifth coil 72A are specifically set so that the resonance frequency of the fourth coil 71A and the fifth coil 72A in terms of the resonance frequency, the material, the diameter, the number of twists, The inner width (or outer width), and the shape. The resonance frequency is, for example, 10 to 100 kHz. The material is, for example, copper or aluminum. The line diameter (more specifically, the small line 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 (for example, 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, U-shaped, C-shaped, or semicircular. The method of winding the twisted wire is, for example, a concentrated winding method or a winding method with a gap.

[Third embodiment]

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

The coil section 46 according to the third embodiment shown in Fig. 12 (a) includes the second coil 49 and the third coil 50 as in the first embodiment. The ends of the second coil 49 and the third coil 50 (the arcuate portion 46c) are disposed adjacent to each other in the connection region 46x. In this case, since there is no large clearance between the coils, the temperature distribution of the heat generating rotating body 44 can be more uniformly maintained than in the case where there is a large clearance between the coils. However, when a current in the same direction is supplied to the second coil 49 and the third coil 50, for example, in the connection region 46x, the current of the second coil 49 and the current of the third coil 50 are opposite Direction, so that the magnetic fluxes are erased from each other. Therefore, as shown in Fig. 13 (a), the region TS1 of the heat generating rotating body 44 opposed to the connecting region 46x has a lower magnetic flux density than other regions of the heat generating rotating body 44. [ As a result, the temperature distribution of the heat generating rotating body 44 may be uneven.

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

The core portion 47B has a plurality of cores 51B (connection portions) which overlap the connection region 46x in the opposite direction D2. The core portion 47B has a plurality of cores 51 (main portions) as cores other than the core 51B. The plurality of cores 51 are arranged at equal intervals in the rotation axis direction D1 in an area excluding the area facing the connection area 46x (area in which the 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 rotational axis direction D1. In other words, a plurality of cores 51 are arranged at a certain interval from each other, while a plurality of cores 51B are arranged adjacent (in contact) with each other. Therefore, the plurality of cores 51B have a higher arrangement density in the rotation axis direction D1 than the plurality of cores 51. [

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

In this regard, in the present embodiment, the arrangement density of the plurality of cores 51B overlapping in the opposite direction D2 with the connection region 46x is higher than the arrangement density of the plurality of cores 51 of other cores. Thus, as shown in Fig. 13 (b), the magnetic flux density in the region around the region TS1 where the magnetic flux density of the heat generating rotating body 44 is lowered can be increased. As a result, the temperature distribution in the rotation axis direction D1 can be made uniform.

Further, the configuration in which the temperature distribution of the heat generating rotary body 44 is made uniform as a whole by adjusting the magnetic flux density around the region where the magnetic flux density of the heat generating rotary body 44 is low is not limited to the structure of the fixing device 40B. For example, as in the fixing device 40X of the image forming apparatus 1X shown in Fig. 16, the core portion 47X includes a plurality of cores 51X overlapping with the connection region 46x in the opposite direction D2, And a plurality of cores 51 that are cores. 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 heat generating rotating body 44 in the opposite direction D2. Specifically, the plurality of cores 51X are closer to the heat generating rotary body 44 than the plurality of cores 51. [ This makes it possible to increase the magnetic flux density in the peripheral region of the region where the magnetic flux density of the heat generating rotating body 44 is lowered (region TS1 opposed to the connection region 46x). As a result, the temperature distribution in the rotation axis direction D1 can be made uniform.

The arrangement density of the respective cores of the core portion and the distance from the heat generating rotary body 44 are made equal to each other and the magnetic permeability of a plurality of cores superimposed in the opposite direction D2 to the coupling region 46x, May be different. More specifically, the magnetic permeability of the core superimposed on the coupling region 46x in the opposite direction D2 can be made higher than that of other cores. This makes it possible to increase the magnetic flux density in the peripheral region of the region where the magnetic flux density of the heat generating rotating body 44 is lowered (region facing the connection region 46x). As a result, the temperature distribution in the rotation axis direction D1 can be made uniform.

The fourth coil 71A and the fifth coil 72A are provided as in the fixing device 40A of the second embodiment and the fourth coil 71A and the fifth coil 72A are connected to the second coil 49A (The image forming apparatus 1) C (see Fig. 18) having a connection area 73x having the same relationship as the connection area 46x of the third coil 50 and the connection area 46x of the third coil 50. Fig. The fixing device 40C has a core portion 47C. The core portion 47C has a plurality of cores 51C (connection portions) overlapping with the connection region 46x and the connection region 73x in the opposite direction D2. The core portion 47C has a plurality of cores 51 (main portions) as cores other than the core 51C. The plurality of cores 51 are arranged at equal intervals in the rotational axis direction D1 except for the region where the cores 51C are provided. The core 51C and the core 51 have the same permeability.

The plurality of cores 51C and the plurality of cores 51 have different arrangement densities in the rotation axis direction D1. That is, a plurality of cores 51 are arranged at a certain interval from each other, while a plurality of cores 51C are arranged adjacent (contact) with each other. Therefore, as compared with the plurality of cores 51, the plurality of cores 51C have a high arrangement density in the rotation axis direction D1.

As described above, the arrangement density of the plurality of cores 51C overlapping in the opposite direction D2 with the connecting region 46x and the connecting region 73x is higher than the arrangement density of the plurality of cores 51 as the other cores. This makes it possible to increase the magnetic flux density in a region around the region where the magnetic flux density of the heat generating rotating body 44 is lowered (region facing the connection region 46x and the connection region 73x). As a result, the temperature distribution in the rotation axis direction D1 can be made uniform.

[Fourth Embodiment]

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

The third embodiment described above is a structure in which the end portions of the second coil 49 and the third coil 50 of the coil portion 46 are disposed adjacent to each other at the connection region 46x. On the other hand, 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 portion 46h are spaced apart from each other in the connecting region 46y . With this arrangement, the second coil 49h and the third coil 50h can be arranged easily.

Here, in the case where the second coil 49h and the third coil 50h are disposed apart from each other, even if a current flows in the same direction in the second coil 49h and the third coil 50h, The same magnetic flux can not be canceled. However, there is a region where no coil exists in the connection region 46y, and no magnetic flux is generated in the region. Thus, as shown in Fig. 13 (a), the region TS1 of the heat generating rotating body 44 opposed to the connecting region 46y has a lower magnetic flux density than the other regions of the heat generating rotating body 44. [ As a result, the temperature distribution of the heat generating rotating body 44 may be uneven. Even in such a case, by the fixing device 40B (see Figs. 14 and 15) and the fixing device 40X (see Fig. 16) described in the third embodiment, the area where the magnetic flux density in the heat generating rotating body 44 is lowered (The region TS1 facing the connection region 46y) (FIG. 13 (b)). As a result, the temperature distribution in the rotation axis direction D1 can be made uniform.

Like the fixing device 40A of the second embodiment, a fourth coil and a fifth coil are provided, and the fourth coil and the fifth coil are provided in the connection region 46y of the second coil 49h and the third coil 50h And the connection area having the same relationship as the connection area. In this case as well, the core portion is configured to increase the magnetic flux density around the region of the heat generating rotating body 44 opposed to the connection region of the fourth coil and the fifth coil, thereby achieving uniformity of the temperature distribution in the rotation axis direction D1 .

[Fifth Embodiment]

Next, a fifth embodiment will be described with reference to Figs. 1 to 16 and Fig. 17. Fig.

In the third embodiment described above, the end portions of the second coil 49 and the third coil 50 of the coil portion 46 are disposed adjacent to each other at the connection region 46x. On the other hand, in the fifth embodiment, as shown in Fig. 12 (c), the end portions of the second coil 49i and the third coil 50i of the coil portion 46i are arranged so as to overlap each other in the opposite direction D2 do. In this case, when a current flows in the same direction in the second coil 49i and the third coil 50i, a current flows in the same direction in the second coil 49i and the third coil 50i in the connection region 46z , The magnetic fluxes generated from the coils reinforce each other.

In this case, as shown in Fig. 17 (a), the region TS2 of the heat generating rotating body 44 opposed to the connecting region 46z has a higher magnetic flux density than the other regions of the heat generating rotating body 44. [ As a result, the temperature distribution of the heat generating rotating body 44 may be uneven.

In the present embodiment, the magnetic flux density around the region where the magnetic flux density is increased is made lower than the magnetic flux density around the region where the magnetic flux density is lowered in the third embodiment. That is, for example, the arrangement densities of the plurality of cores superimposed on the connection region 46z in the opposite direction D2 are made lower than the arrangement density of the other plurality of cores. In addition, for example, the distance from the heat generating rotary body 44 of the plurality of cores superimposed on the connection region 46z in the opposite direction D2 is made longer than the distance from the heat generating rotary body 44 of the other cores . Further, for example, the magnetic permeability of a plurality of cores superimposed on the coupling region 46z in the opposite direction D2 is made lower than that of the other cores. Thus, as shown in Fig. 17 (b), the magnetic flux density in the region around the region TS3 where the magnetic flux density of the heat generating rotating body 44 is increased can be made low. As a result, the temperature distribution in the rotation axis direction D1 can be made uniform.

Like the fixing device 40A of the second embodiment, a fourth coil and a fifth coil are provided, and the fourth coil and the fifth coil are connected to each other through the connecting region 46z (46z) between the second coil 49i and the third coil 50i, Quot;) < / RTI > is provided. In this case as well, by configuring the core portion so as to lower the magnetic flux density in the peripheral region of the region of the heat generating rotating body 44 opposed to the connection region of the fourth coil and the fifth coil, uniformity of the temperature distribution in the rotation axis direction D1 .

[Sixth Embodiment]

Next, the image forming apparatus according to the sixth embodiment will be described with reference to Figs. 1 to 18, and further with Figs. 19 to 22. Fig.

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

In the fixing apparatus 40D, the control section (Fig. 7: 65) controls at least one of the power supply section 62 and the switching connection section 64. [ The control unit 65 individually sets control patterns of at least any one of the power supply unit 62 and the switching connection unit 64 in accordance with the paper feeding status.

The control section 65 controls the switch connection section 64 so as to be converted into two serial connection types (first serial connection type and second serial connection type) by outputting the switching signal to the switching connection section 64, do. In the first series connection mode, 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 in the same direction, Each coil is connected in series. 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 in the second series connection mode So that 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 the control pattern for controlling the switch connection section 64, respectively.

Further, the control unit 65 can set a control pattern different from the control pattern according to the above-described two types of serial connection by controlling the power supply by the power supply unit 62. [ That is, according to the control pattern according to the above-described two types of series connection, power is supplied to all the coils but the control pattern in which no power is supplied to a part of the coils Pattern to be set). 19 (c)) that does not supply power to the second coil 49 and a control pattern (Fig. 19 (d) that does not supply power to the third coil 50) Can be included in the pattern.

Since various kinds of control patterns can be set in this way, temperature distributions of various shapes can be realized in the rotation axis direction D1. That is, in addition to the temperature distribution ga and the temperature distribution gb in accordance with the control pattern of the two series connection modes shown in Fig. 20, It is also possible to realize the distribution gc and the temperature distribution gd in accordance with the control pattern that does not supply electric power to the third coil 50 and the like. This makes it possible to equalize the temperature distribution of the heat generating rotating body 44 according to various situations.

A method for controlling the power supply of the power supply unit 62 by the control unit 65 is not particularly limited. For example, a bypass route may be provided in parallel with each coil in the series connection circuit, Or by selecting a coil or a bypass route by means of the control signal to control the presence or absence of electric power supply to each coil.

Various control patterns are shown in Fig. 21 (a) to 21 (g) show control patterns A1 to A7, respectively. In the control pattern A1, the above-described first series connection mode is selected in a serial connection manner, and power supply to all the coils is performed (Fig. 21 (a)). In the control pattern A2, the first series connection mode (or the above-described second series connection mode) is selected as the series connection mode, and power is supplied only to the first coil 48 (FIG. 21 (b)). In the control pattern A3, the first series connection mode (or the second series connection mode) is selected as the series connection mode, and power is supplied only to the first coil 48 and the third coil 50 (c). In the control pattern A4, the second serial connection mode is selected as the serial connection mode, and at the same time, the power supply to all the coils is performed (Fig. 21 (d)). In the control pattern A5, the first serial connection mode (or the second serial connection mode) is selected as the series connection mode, and power is supplied only to the third coil 50 (Fig. 21 (e)). In the control pattern A6, the first series connection mode is selected as the series connection mode, and power is supplied only to the second coil 49 (Fig. 21 (f)). In the control pattern A7, the first series connection mode is selected as the series connection mode, and power is supplied only to the first coil 48 and the second coil 49 (Fig. 21 (g)).

An example of setting the control pattern is shown in Fig. 22 shows an appropriate control pattern according to the type of paper, the width of the paper, and whether the paper is passing through or between the paper and the paper. The type of paper is either plain paper or thick paper. Plain paper has a basis weight of 60.2 to 104.7 g / m ² , and thick paper has a basis weight of 104.7 to 216.0 g / m ² . The paper passing state means that the paper is passing through the heat generating rotating body 44 and includes the paper feeding start time, the continuous paper feeding time, and the paper feeding ending time. Also, between paper and paper means paper preparation time. Whether the target temperature (the target temperature of the heating rotator 44) + 3 ° C or more, the target temperature ± 3 ° C, or the target temperature -3 ° C or less is a condition for determining the control pattern when the sheet is passing. In the case of the paper between the paper and the paper, the control pattern is set when the temperature is equal to or lower than the target temperature. When the temperature is higher than the target temperature, the control pattern is not set (changed). 22, the length of the first coil 48 in the rotation axis direction D1 is 300 mm, the length in the rotation axis direction D1 of the second coil 49 and the third coil 50 Is 100 mm, respectively.

21 (e)) is selected when the paper type is plain paper, the paper width is 151 mm to 200 mm, the paper is passing, and the target temperature of the heat generating rotating body 44 is + 3 ° C or more . The control pattern OFF is selected when the paper type is plain paper, the paper width is 101 mm to 150 mm, the paper is passing, and the target temperature of the heat generating rotating body 44 is + 3 ° C or more. Control pattern OFF indicates a case where a control pattern is not newly set.

The example of the setting of the control pattern is only an example, and the condition at the time of determining the control pattern is only an example. For example, it is described that the condition is whether the sheet is passing through the sheet or between the sheet and the sheet. More specifically, the sheet may be prepared for feeding, at the start of feeding, at the time of continuous feeding, and at the end of feeding. Since the control pattern is determined in accordance with the feeding condition, it is possible to suppress the power supply of the non-feeding instruction compared to, for example, feeding, and the temperature distribution of the heating rotator 44 can be made uniform in various situations .

Further, since the control pattern is determined according to the width of the paper as in the control pattern of Fig. 22, an appropriate control pattern corresponding to various paper widths is selected, and when the paper of various widths is fed, So that uniformity can be achieved. Since the control pattern is determined according to the thickness of the paper, the temperature distribution of the heat generating rotating body 44 can be made uniform when paper of various thicknesses is fed.

Since the control pattern is determined according to the difference between the measured temperature of the heat generating rotating body 44 and the target temperature, an appropriate control pattern can be selected in accordance with the temperature condition of the heat generating rotating body 44.

[Seventh 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.

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

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

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

Fig. 24 shows the control patterns B7 to B12. In the control pattern B7, power is supplied to all the 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 mode in which the current direction of the second coil 49 and the fourth coil 71A is opposite to the current direction of the other coils is selected and all the coils except for the fifth coil 72A (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 mode in which the current direction of the second coil 49 is the same as the current direction of the first coil 48 is selected and power is supplied only to the second coil 49 (e)). In the control pattern B12, a series connection type in which the current direction of the fourth coil 71A is the same as the current direction of the first coil 48 is selected, and power is supplied only to the fourth coil 71A (f).

An example of setting the control pattern is shown in Fig. The various conditions for determining the control pattern are the same as the conditions of the control pattern in Fig. 22 described in the fifth embodiment. An example of setting the control pattern shown in Fig. 25 is that the length of the first coil 48 in the direction of the axis of rotation D1 is 300 mm, the length of the second coil 49 and the direction of the axis of rotation D1 of the third coil 50 The length of the fourth coil 71A in the rotation axis direction D1 is 50 mm and the length of the fifth coil 72A in the rotation axis direction D1 is 200 mm.

For example, the control pattern B9 is selected when the paper type is plain paper, the paper width is 151 mm to 200 mm, the paper is passing, and the target temperature of the heat generating rotating body 44 is + 3 ° C or more. The control pattern OFF is selected when the paper type is plain paper, the paper width is less than 100 mm, the paper is passing, and the target temperature of the heat generating rotating body 44 is + 3 ° C or more. Control pattern OFF indicates a case where a control pattern is not newly set.

[Eighth Embodiment]

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

As shown in Fig. 26, the image forming apparatus 1F includes a fixing device 40F. The fixing device 40F includes a coil portion 46A (see Figs. 10 and 11) in the same manner as the fixing device 40A of the second embodiment. The fixing device 40F also includes a temperature detection sensor 80 for detecting the temperature of the heat generating rotating body 44. [ 26, only the configuration according to the coil part 46A and the temperature detection sensor 80 in the configuration of the fixing device 40F is shown. Although the temperature detection sensor 80 is shown as being disposed on the coil section 46A for the sake of convenience in the description of Fig. 26, in reality, the temperature detection sensor 80 is located just under or around the heat generating rotator 44 .

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 heat generating rotating body 44 overlapping with 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 is provided with a heat generating rotary body 44 which overlaps with the portion where the first coil 48, the second coil 49 and the fifth coil 72A are overlapped with each other in the opposite direction D2, The temperature of the region is detected. The third temperature detecting sensor 83 detects the temperature of the heat generating rotary body 44 which overlaps the portion where the second coil 49 and the fourth coil 71A overlap with each other in the opposite direction D2.

It can be determined from the value of the temperature detection sensor 80 whether or not the temperature distribution of the heat generating rotating body 44 is abnormal. Thus, it is possible to judge whether or not an erroneous sheet (different from the setting) is being fed. Hereinafter, this will be described in detail with reference to Fig.

27 is a diagram showing the temperature distribution in the heat generating rotating body 44 for each paper size (actual size) of actually fed paper with respect to a previously set paper size (set size). Here, in the fixing device 40F, the first sheet S1, the second sheet S2 having a wider width than the first sheet, and the third sheet S3 having a wider width than the second sheet can be fed. In addition, the length of the first coil 48 in the direction of the axis of rotation D1 is larger than the width of the third sheet S3. 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. The length of the fifth coil 72A in the rotational axis direction D1 is smaller than the width of the third sheet S3 and larger than the width of the second sheet S2. By using the paper and the coil of this size, the paper-feeding error can be appropriately determined by the above-described temperature detection sensor 80. [

It is preferable that the length of the first coil 48 in the direction of the axis of rotation D1 is 5 to 10% larger than the width of the third sheet S3 in order to improve the accuracy of feeding error determination by the temperature sensor 80 Do. The length of the third coil 50 in the direction of the axis of rotation D1 is preferably 5 to 10% larger than the width of the first sheet S1. 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, the case where the set size matches the actual size, that is, the case where the paper feeding error does not occur will be described. For example, when the setting size is the size of the third sheet S3, the current directions of all the coils are the same direction. In this state, when the third sheet S3 having a width larger than that of the fifth coil 72A is fed (Fig. 27 (a)), the detection portion of all the temperature detection sensors 80 becomes the paper feeding portion. Therefore, the temperatures detected by the first temperature detection sensor 81, the second temperature detection sensor 82, and the third temperature detection sensor 83 are the same. When the set size is the size of the third sheet S3 and the values of all the temperature detecting sensors 80 are equal to each other, it can be determined that the sheet feeding error does not occur.

For example, when the setting size is the size of the second sheet S2, only the current direction of the fourth coil 71A is opposite to the current direction of the other coil. In this state, when the second sheet S2 which is wider than the third coil 50 and narrower than the fifth coil 72A is fed (Fig. 27 (e)), the third temperature detection Only the value of the sensor 83 is compared with the values of the first temperature detection sensor 81 and the second temperature detection sensor 82 and is lowered by a predetermined value. When the setting size is the size of the second sheet S2 and only the value of the third temperature sensor 83 is lowered by a predetermined value, it can be determined that the sheet feeding error does not occur.

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

On the other hand, when the set size and the actual size do not match, that is, when a paper feeding error occurs, the temperature detecting sensor 80 performs temperature detection different from the case where the paper feeding error does not occur. 27 (d)), only the value of the third temperature detection sensor 83 is detected as the first temperature detection (step S200). In this case, when the paper size of the third paper S3 is set and the second paper S2 is fed Which is higher than the values of the sensor 81 and the second temperature detection sensor 82. [ The temperature difference is caused by the fact that a part of the heat is transmitted to the sheet at the portion through which the sheet passes and the temperature of the sheet passing portion is lower than the portion where the sheet does not pass. In this case, since the values of all the temperature detection sensors 80 must be substantially the same, the control unit 65 can determine that a paper feeding error has occurred. When the temperature detection state by the temperature detection sensor 80 is the same as the state in which the second sheet S2 is fed (the detection values of the first and second temperature detection sensors 81 and 82 are substantially the same, 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 sheet 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 can change the setting size to an appropriate setting size.

[Ninth Embodiment]

Next, an image forming apparatus according to a ninth embodiment will be described with reference to Figs. 1 to 27, and further with Fig.

As shown in Fig. 28, the image forming apparatus 1G includes a fixing device 40G. The fixing device 40G has a coil portion 46 like the fixing device 40 of the first embodiment. Further, the fixing device 40G includes a temperature detection sensor 80G for detecting the temperature of the heat generating rotating body. 28 shows only the configuration of the coil part 46 and the temperature detection sensor 80G in the configuration of the fixing device 40G. Although the temperature detection sensor 80G is shown as being disposed on the coil portion 46 for convenience of explanation, the temperature detection sensor 80G actually detects the temperature sensor 80G just under or around the heat generating rotator 44 .

The fixing device 40F according to the eighth embodiment shown in Fig. 26 is provided with three temperature detecting sensors 80 for the coil portion 46A having a three-layer structure, but the fixing device 40G has the two- Two temperature detecting sensors 80 are provided for the coil portion 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 heat generating rotary body 44 which overlaps the central portion of the first coil 48 and the third coil 50 in the direction of the rotation axis D1 in the direction D2, do. The second temperature detection sensor 83G is a sensor for detecting the temperature of the region of the heat generating rotary body 44 overlapping with the portion where the first coil 48 and the second coil 49 overlap with each other in the opposite direction D2 and in the opposite direction D2 The temperature is detected.

According to such a configuration, the feeding error can be detected even in the coil configuration of the two-layer structure constituted by the first coil 48, the second coil 49 and the third coil like the coil part 46. [ That is, the error of the actual size with respect to the set size can be detected according to the temperature of the first temperature detecting sensor 81G and the temperature of the second temperature detecting sensor 83G.

The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments. For example, although the number of turns of the second coil 49 and the number of turns of 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 48 .

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 larger than the inner width IW2 of the first coil 48, 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.

Further, although the number of turns of the second coil 49 and the number of turns of the third coil 50 are described as being the same, they may be different. It is not always necessary that the first coil 48 is located 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. For example, the first coil 48 and the third coil 50, through which the current always flows in the same direction, may be formed as an integral coil.

The above-described embodiments are merely illustrative, and various modifications and equivalent other embodiments are possible without departing from the scope of the present invention. Accordingly, the true scope of protection of the present invention should be determined by the technical idea of the invention described in the following claims.

1, 1A, 1B, 1C, 1D, 1E, 1F, 1G,
40, 40A, 40B, 40C, 40D, 40E, 40F, 40G, 40X:
44: heat generating rotary member 44a: outer peripheral surface
46, 46A, 46h, 46i: coil part 46c: arc part
46x, 46y, 46z, 73x: connection areas 47, 47B, 47C, 47X:
48: first coil 48x:
48y: central portion 49, 49h, 49i: second coil
50, 50h, 50i: third coil 51, 51B, 51C, 51X: core
62: power supply unit 63:
64: Switching connection part 65:
71A: fourth coil 72A: fifth coil
80, 80G: temperature detecting sensor 81, 81G: first temperature detecting sensor
82, 83G: second temperature detecting sensor 83: third temperature detecting sensor
D1: rotation axis direction D2: opposite direction
IW1, IW2: Inner width OW1, OW2: Outer width
T1: Direction of rotation

Claims (20)

A rotatable heating element;
And a coil unit circuit which generates a magnetic flux for heating the heating element and includes a coil part arranged to be spaced apart from the outer circumferential surface of the heating element in the opposite direction and a power supply part for supplying electric power to the coil part,
Wherein the coil portion includes:
A first coil disposed along a width direction of the heating element;
A pair of second coils disposed on both ends of the first coil in the width direction so as to overlap in the opposite direction; And
And a third coil disposed in the width direction center portion of the first coil so as to overlap in the opposite direction,
Wherein the coil unit circuit includes a switching connection portion for switching a serial connection form 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 . The method according to claim 1,
Wherein the number of turns of the second coil is smaller than the number of turns of the first coil. The method according to claim 1,
Wherein an inner width of the second coil and the third coil is larger 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 in a rotating direction of the heating element, . The method according to claim 1,
Wherein the second coil and the third coil have the same distance from the heating element in the opposed direction and the number of turns. The method according to claim 1,
And the second coil and the third coil are connected,
A structure in which the end portions in the width direction are disposed adjacent to each other and a structure in which the end portions in the width direction are spaced apart from each other; and a structure in which a distance from the heat generating element in the opposite direction is different, And the fixing device is arranged in a structure of being superimposed on the fixing device. The method according to claim 1,
And a core portion having a plurality of cores for concentrating the magnetic flux generated by the first coil, the second coil and the third coil on the heating element,
And the core portion is disposed at a position overlapping at least the second coil and the third coil in the width direction. The method according to claim 6,
Wherein the first coil is disposed at a position closer to the core portion than the second coil and the third coil in the opposing direction. The method according to claim 6,
The core portion
A connecting portion which overlaps with the connecting 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
And a main part overlapping with the coil part other than the connection part,
Wherein the connecting portion and the main portion are provided with:
A structure in which the plurality of cores have different arrangement densities and different permeabilities from each other and a structure in which the plurality of cores have different permeabilities and a structure in which distances in the opposite directions are different from the heating elements of the plurality of cores . The method according to claim 1,
Wherein the 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 according to claim 1,
Wherein the coil portion includes:
A pair of fourth coils arranged to overlap with the widthwise opposite ends of the first coil and the second coil in the opposite direction; And
And a fifth coil disposed to overlap the first coil and the third coil in the width direction central portion and in the opposite direction,
The ratio of the fourth coil and the fifth coil in the width direction is different from the ratio of the width direction length of the second coil and the third coil,
Wherein the switching connection portion connects the first coil, the second coil, the third coil, the fourth coil and the fifth coil in series and connects the first coil, the second coil, the third coil, And switches the series connection mode of the first coil, the second coil, the third coil, the fourth coil and the fifth coil so that the current direction of the fourth coil and the fifth coil is switched. 11. The method of claim 10,
Wherein the 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 according to claim 1,
Wherein the coil unit circuit further comprises a control unit for controlling at least one of the power supply unit and the switching connection unit,
Wherein the control unit individually sets control patterns of at least any one of the power supply unit and the switching connection unit at the time of paper feed preparation, at the start of feeding, at the time of continuous feeding, and at the time of termination of feeding. 13. The method of claim 12,
Wherein the control pattern includes a pattern for setting supply and stop of electric power by the electric power supply unit. 13. The method of claim 12,
Wherein the control pattern includes a pattern for setting a serial connection form of the coil portion by the switching connection portion. 13. The method of claim 12,
Wherein the control unit has a plurality of control patterns. 16. The method of claim 15,
Wherein,
Wherein the control pattern is determined according to at least one of a width of the recording medium, a thickness of the recording medium, and a difference between the measurement temperature of the heating element and the target temperature. The method according to claim 1,
A first temperature detection sensor for detecting a temperature of a region of the heating element which is overlapped with the center portion in the width direction of the first coil and the third coil in the opposite direction; And
And a pair of second temperature detection sensors for detecting a temperature of a region of the heating element where the first coil and the second coil overlap each other in the opposing direction and a region overlapping in the opposing direction Fixing device. 18. The method of claim 17,
Wherein the coil portion includes:
A pair of fourth coils arranged to overlap with the widthwise opposite ends of the first coil and the second coil in the opposite direction;
And a fifth coil disposed to overlap the first coil and the third coil in the width direction central portion and in the opposite direction,
The fifth coil is arranged to overlap with the third coil side end of the second coil in the opposite direction,
The fixing device includes:
Further comprising a pair of third temperature detection sensors for detecting the temperature of a region of the heating element where the second coil and the fifth coil overlap each other and a region overlapping in the opposite direction,
The first temperature detecting sensor detects the temperature of a region of the first coil, the third coil, and the fifth coil overlapping with the widthwise central portion in the opposed direction of the region of the heating element,
Wherein the second temperature detection sensor detects a temperature of a region of the heating element where the first coil, the second coil, and the fifth coil overlap each other and a region overlapping in the opposite direction. 19. The method of claim 18,
When a first recording medium, a second recording medium that is wider than the first recording medium, and a third recording medium that is wider than the second recording medium are fed,
The length of the first coil in the width direction is larger than the width of the third recording medium,
The length of the third coil in the width direction is smaller than the width of the second recording medium and is larger than the width of the first recording medium,
Wherein a width 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