JP3842234B2 - Induction heating fixing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fixing device that is mounted on an image forming apparatus such as a copying machine or a printer and fixes a developer image on a sheet.
[0002]
[Prior art]
In an image forming apparatus using digital technology such as an electronic copying machine, a document table on which a document is placed is exposed, and reflected light from the document table is guided to a photoelectric conversion element such as a CCD (charge coupled device).
[0003]
The CCD outputs an image signal corresponding to the original image. Laser light corresponding to the image signal is irradiated onto the photosensitive drum, and an electrostatic latent image is formed on the peripheral surface of the photosensitive drum. This electrostatic latent image is visualized by the adhesion of developer (toner). A sheet is fed to the photosensitive drum in synchronization with the rotation of the photosensitive drum, and a visible image (developer image) on the photosensitive drum is transferred to the sheet. The sheet on which the developer image is transferred is sent to a fixing device.
[0004]
The fixing device includes a heating roller and a pressure roller that rotates with the heating roller while being in contact with the heating roller in a pressurized state. The developer image on the paper is fixed by heat.
[0005]
There is induction heating as a heat source of the heating roller. This is because a coil is placed in a heating roller, a capacitor is connected to the coil to form a resonance circuit, and the resonance circuit is excited at one frequency with respect to one resonance circuit, whereby a high-frequency current is passed through the coil. A high frequency magnetic field is generated from the coil, an eddy current is generated in the heating roller by the high frequency magnetic field, and the heating roller self-heats by Joule heat generated by the eddy current.
[0006]
This fixing device using induction heating heats a fixing roller made of a metal conductor by eddy current due to electromagnetic waves, and an induction coil spirally wound around a non-magnetic bobbin is provided in the fixing roller. By causing a high-frequency current to flow through the induction coil, an induced eddy current is generated in the fixing roller by a high-frequency magnetic field generated thereby, and the fixing roller itself is heated by Joule heat by the skin resistance of the fixing roller. This bobbin is divided into three parts: a central main bobbin member and a slave bobbin member connected to both sides of the bobbin member for the purpose of easy manufacture and repair, and a conductive wire is wound around each of the divided bobbin members. Thus, an induction coil is configured (see, for example, Patent Document 1).
[0007]
[Patent Document 1]
Japanese Patent Laying-Open No. 2001-312165 (page 2-3, FIG. 1)
[0008]
[Problems to be solved by the invention]
In recent years, shortening W / U has become a technical issue as an energy-saving technology, but as a countermeasure, the heating roller can be made thinner. However, since various types of paper sizes are used in the fixing device, when the narrow paper is continuously passed, the outside of the paper on the heating roller is not deprived of heat by the paper. The phenomenon that fixing failure due to high temperature offset occurs when a wide sheet is passed after a narrow sheet becomes high due to the fact that the heating roller is thick. The thinner (the smaller the heat capacity), the more prominent.
[0009]
Further, in manufacturing the coil constituting the fixing device, further efficiency and ease of manufacturing have been demanded.
[0010]
The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide an induction heating fixing device excellent in practicality and reliability that can solve the above-described problems.
[0011]
[Means for Solving the Problems]
The magnetic field generator of the invention according to claim 1 has flanges projecting outward at both ends of the bobbin main body, and the flanges at both ends are arranged at different positions so as not to overlap each other in the axial direction.
[0012]
In the magnetic field generator according to the second aspect of the present invention, a groove extending radially is provided on the end face of the bobbin main body, and flanges are provided on both sides of the groove.
[0013]
The magnetic field generator of the invention which concerns on Claim 3 and 4 forms the some frame-shaped electric wire guide in the bobbin main body.
[0014]
In the magnetic field generator of the invention according to claim 5, the wire guides are arranged symmetrically, and both end faces of the bobbin main body are formed to be asymmetric.
[0015]
The magnetic field generator of the invention according to claims 6 and 7 has a plurality of ribs in the bobbin body, the holder abuts on the ribs, and the arrangement angle between the ribs is set to be less than 180 °.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0017]
First, FIG. 1 shows an internal configuration of an image forming apparatus such as a composite electronic copying machine. A transparent document table (glass plate) 2 for placing a document is provided on the upper surface of the main body 1, and the document is placed on the document table 2 by turning on an exposure lamp 5 provided on the carriage 4. Document D is exposed.
[0018]
The reflected light by this exposure is projected onto a photoelectric conversion element such as a CCD (Charge Coupled Device) 10 to output an image signal. The image signal output from the CCD 10 is converted into a digital signal. The digital signal is appropriately processed and then supplied to the laser unit 27. The laser unit 27 emits a laser beam B according to the input signal.
[0019]
Although not shown, a control panel for setting operating conditions is provided on the upper surface of the main body 1 at a position where the automatic document feeding unit 40 does not cover. The control panel includes a touch panel type liquid crystal display, a numeric keypad for inputting numerical values, a copy key, and the like.
[0020]
On the other hand, a photosensitive drum 20 is rotatably provided at a substantially central portion in the main body 1. Around the photosensitive drum 20, a charger 21, a developing unit 22, a transfer unit 23, a peeling unit 24, a cleaner 25, and a static eliminator 26 are sequentially arranged. The photosensitive drum 20 is formed by a known process method. A toner image is formed thereon, the toner image is transferred onto the paper, and the toner on the paper is heated and pressurized and fixed by a fixing device 100 described later.
[0021]
A specific configuration of the fixing device 100 is shown in FIG.
[0022]
A heating roller 101 and a pressure roller 102 are provided at positions where the conveyance path of the copy paper S is sandwiched up and down. The pressure roller 102 is in pressure contact with the peripheral surface of the heating roller 101 by a pressure mechanism (not shown). The contact portions of these rollers 101 and 102 have a constant nip width.
[0023]
The heating roller 101 is formed by forming a conductive material, for example, iron into a cylindrical shape, and coating the outer peripheral surface of the iron with Teflon or the like, and is driven to rotate rightward in the drawing. The pressure roller 102 rotates in the left direction in the figure in response to the rotation of the heating roller 101. The copy sheet S passes through the contact portion between the heating roller 101 and the pressure roller 102, and the copy sheet S receives heat from the heating roller 101, whereby the developer image T on the copy sheet S is applied to the copy sheet S. It is fixed.
[0024]
Around the heating roller 101, a peeling claw 103 for peeling the copy paper S from the heating roller 101, a cleaning member 104 for removing toner and paper debris remaining on the heating roller 101, and a mold release on the surface of the heating roller 101 An application roller 105 for applying the agent is provided.
[0025]
A coil 111 for induction heating is accommodated inside the heating roller 101. The coil 111 is wound and held on the bobbin 112 and emits a high-frequency magnetic field for induction heating. When this high-frequency magnetic field is generated, an eddy current is generated in the heating roller 101, and the heating roller 101 self-heats due to Joule heat generated by the eddy current.
[0026]
A control circuit of the main body 1 is shown in FIG.
[0027]
A scan CPU 70, a control panel CPU 80, and a print CPU 90 are connected to the main CPU 50. The main CPU 50 controls the scan CPU 70, the control panel CPU 80, and the print CPU 90 in an integrated manner. The main CPU 50 controls the copy mode according to the copy key operation, and the printer mode according to the image input to the network interface 59 described later. Control means, and FAX (facsimile) mode control means corresponding to image reception by a FAX transmission / reception unit 60 described later.
[0028]
Further, a ROM 51 for storing a control program, a RAM 52 for storing data, a pixel counter 53, an image processing unit 55, a page memory controller 56, a hard disk unit 58, a net interface 59, and a FAX transmission / reception unit 60 are connected to the main CPU 50. Yes. The page memory controller 56 controls writing and reading of image data with respect to the page memory 57. The image processing unit 55, the page memory controller 56, the page memory 57, the hard disk unit 58, the net interface 59, and the FAX transmission / reception unit 60 are connected to each other by the image data bus 61.
[0029]
The network interface 59 functions as an input unit for a printer mode to which an image (image data) transmitted from an external device is input. A communication network 201 such as a LAN or the Internet is connected to the net interface 59, and external devices such as a plurality of personal computers 202 are connected to the communication network 201. These personal computers 202 include a controller 203, a display 204, and an operation unit 205.
[0030]
The FAX transmission / reception unit 60 is connected to a telephone line 210 and functions as a reception unit for a facsimile mode for receiving an image (image data) transmitted by facsimile through the telephone line 210.
[0031]
A ROM 71 for storing a control program, a RAM 72 for storing data, a signal processing unit 73 that processes the output of the CCD 10 and supplies it to the image data bus 61, a CCD driver 74, a scan motor driver 75, and an exposure lamp 5 The automatic document feeder 40 and a plurality of document sensors 11 are connected. The CCD driver 74 drives the CCD 10. The scan motor driver 75 drives a scan motor 76 for driving the carriage. The automatic document feeder 40 has a document D set on the tray 41 and a document sensor 43 for detecting the size of the document D.
[0032]
Connected to the control panel CPU 80 are a touch panel type liquid crystal display unit 14, a numeric keypad 15, an all reset key 16, a copy key 17, and a stop key 18 of the control panel.
[0033]
A ROM 91 for storing a control program, a RAM 92 for storing data, a print engine 93, a paper transport unit 94, a process unit 95, and the fixing device 100 are connected to the print CPU 90. The print engine 93 is configured by the drive circuit of the laser unit 27 and the like. The paper transport unit 94 is composed of a paper transport mechanism from the paper feed cassette 30 to the tray 38 and its drive circuit. The process unit 95 is constituted by the photosensitive drum 20 and its peripheral part.
[0034]
A print unit that prints the image processed by the image processing unit 55 on the paper P is mainly configured by the print CPU 90 and its peripheral configuration.
[0035]
An electric circuit of the fixing device 100 is shown in FIG.
[0036]
The coil 111 in the heating roller 101 is divided into three coils 111a, 111b, and 111c. Among these, the coil 111a exists in the center part of the heating roller 101, and the coils 111b and 111c exist in the both-sides position which pinches | interposes the coil 111a. For example, all the coils 111a, 111b, and 111c are used for fixing a large size paper S, and only the coil 111a is used for fixing a small size paper S. These coils 111a, 111b, and 111c are connected to the high frequency generation circuit 120.
[0037]
A temperature sensor 112 for detecting the temperature of the central portion of the heating roller 101 is provided. A temperature sensor 113 for detecting the temperature of one end of the heating roller 101 is provided. These temperature sensors 112 and 113 are connected to the print CPU 90 together with a drive unit 160 for rotationally driving the heating roller 101. In addition to the function of controlling the drive unit 160, the print CPU 90 operates an after-mentioned first series resonance circuit (output power P1) having the coil 111a as a component, and a later-described second having the coils 111b and 111c as components. The function of issuing a P1 / P2 switching signal for designating the operation of the series resonance circuit (output power P2), and the function of controlling the output power P1, P2 of each series resonance circuit according to the detected temperature of the temperature sensors 112, 113 I have.
[0038]
The high frequency generation circuit 120 generates high frequency power for generating a high frequency magnetic field, and includes a rectifier circuit 121 and a switching circuit 122 connected to an output terminal of the rectifier circuit 121. The rectifier circuit 121 rectifies the AC voltage of the commercial AC power supply 130. The switching circuit 122 forms a first series resonance circuit by the coil 111a and the capacitors 123 and 125, and forms a second series resonance circuit by the series body of the coils 111b and 111c and the capacitors 124 and 125, and switches these series resonance circuits. The element is selectively excited by a transistor 126 such as an FET.
[0039]
The first series resonance circuit has a resonance frequency f1 determined by the inductance L1 of the coil 111a, the capacitance C1 of the capacitor 123, and the capacitance C3 of the capacitor 125. The second series resonance circuit has a resonance frequency f2 determined by the combined inductance L2 of the coils 111b and 111c, the capacitance C2 of the capacitor 124, and the capacitance C3 of the capacitor 125.
[0040]
The transistor 126 is turned on and off by the controller 140 in accordance with a P1 / P2 switching signal from the print CPU 90. The controller 140 includes an oscillation circuit 141 and a CPU 142. The oscillation circuit 141 generates a drive signal having a predetermined frequency for the transistor 126. The CPU 142 controls the oscillation frequency (frequency of the drive signal) of the oscillation circuit 141, and has the following means (1) and (2) as main functions.
[0041]
(1) When the operation of the first series resonance circuit (using only the coil 111a) is designated by the P1 / P2 switching signal from the print CPU 90, the first series resonance circuit is set to a plurality of frequencies in the vicinity of the resonance frequency f1, for example, Control means for exciting sequentially (alternately) at (f1−Δf) and (f1 + Δf).
[0042]
(2) When the operation of the first and second series resonant circuits (use of all the coils 111a, 111b, 111c) is specified by the P1 / P2 switching signal from the print CPU 90, the first and second series resonant circuits Means for sequentially exciting at a plurality of frequencies in the vicinity of the respective resonance frequencies f1, f2, for example (f1-Δf), (f1 + Δf), (f2-Δf), (f2 + Δf).
[0043]
Next, the operation of the above configuration will be described.
[0044]
When a drive signal having the same frequency (or a nearby frequency) as the resonance frequency f1 of the first series resonance circuit is emitted from the oscillation circuit 141, the transistor 126 is turned on and off by the drive signal, thereby exciting the first series resonance circuit. The By this excitation, a high frequency magnetic field is generated from the coil 111a, an eddy current is generated in the axial central portion of the heating roller 101 by the high frequency magnetic field, and the axial central portion of the heating roller 101 is self-heated by Joule heat due to the eddy current. .
[0045]
When a drive signal having the same frequency (or a nearby frequency) as the resonance frequency f2 of the second series resonance circuit is emitted from the oscillation circuit 141, the transistor 126 is turned on and off by the drive signal, and the second series resonance circuit is excited. The By this excitation, a high frequency magnetic field is generated from the coils 111b and 111c, and the eddy current is generated on both sides in the axial direction of the heating roller 101 by the high frequency magnetic field. Fever.
[0046]
The relationship between the output power P1 of the first series resonance circuit and the frequency for exciting the first series resonance circuit, and the relationship between the output power P2 of the second series resonance circuit and the frequency for exciting the second series resonance circuit are shown. This is shown in FIG.
[0047]
That is, the output power P1 of the first series resonance circuit becomes a peak level when excited at the same frequency as the resonance frequency f1 of the first series resonance circuit, and becomes a peak as the excited frequency goes away from the resonance frequency f1. The pattern gradually decreases. Similarly, the output power P2 of the second series resonance circuit becomes a peak level when excited at the same frequency as the resonance frequency f2 of the second series resonance circuit, and becomes a peak as the excited frequency goes away from the resonance frequency f2. The pattern gradually decreases.
[0048]
When fixing a large size sheet S, both the first and second series resonance circuits are excited, and high frequency magnetic fields are emitted from all the coils 111a, 111b, and 111c. An eddy current is generated in the entire heating roller 101 by the high-frequency magnetic field, and the entire heating roller 101 self-heats due to Joule heat generated by the eddy current.
[0049]
In this case, drive signals having two frequencies (f1−Δf) and (f1 + Δf) that are separated by a predetermined value Δf in the vertical direction around the resonance frequency f1 of the first series resonance circuit are sequentially output from the oscillation circuit 141. Subsequently, drive signals having two frequencies (f2−Δf) and (f2 + Δf) separated by a predetermined value Δf in the vertical direction around the resonance frequency f2 of the second series resonance circuit are sequentially output from the oscillation circuit 141. Is done.
[0050]
By these drive signals, the first series resonance circuit is sequentially excited at two frequencies (f1−Δf) and (f1 + Δf) sandwiching the resonance frequency f1, and then, the second series resonance circuit has its resonance frequency f2. Are sequentially excited at two frequencies (f2−Δf) and (f2 + Δf). The excitation for each frequency is repeated.
[0051]
As shown in FIG. 5, the output power P1 of the coil 111a in the first series resonance circuit becomes a value P1a slightly lower than the peak level P1c at the time of excitation at the frequency (f1−Δf), and the frequency (f1 + Δf The value P1b slightly lower than the peak level P1c is also obtained at the time of excitation. The output power P2 of the coils 111b and 111c in the second series resonance circuit has a value P2a that is slightly lower than the peak level P2c at the time of excitation at the frequency (f2−Δf), and also peaks at the time of excitation at the frequency (f2 + Δf). The value P2b is slightly lower than the level P2c.
[0052]
An outline of a magnetic field generator (hereinafter referred to as a coil) 111 according to the present invention is shown in FIG.
[0053]
For example, the coil 111 is wound around six bobbins 300 and is arranged on both sides of the center coil 111a having a coil portion 301 divided into six parts. For example, the coils 111 are wound around three bobbins 300, respectively. It is comprised from the side coils 111b and 111c which have the coil part 301 divided into three. The plurality of bobbins 300 are sequentially fitted to a single holder, which will be described later, and both ends of the holder are fixed by a cap 302 or the like, and each coil portion 301 is formed from one side of the cap 302. The same kind of leader lines 303 are bundled and derived in a lump.
[0054]
As shown in FIG. 7, this coil 111 is electrically connected to one end of each coil part 301, that is, for example, the low voltage side for 0V to the common terminal 304 and the other end of the coil part 301 of the center coil 111a. For example, a high potential end of 1000V, for example, which is the other end of both side coils 111b and 111c, is commonly connected to the first terminal 305 on the high voltage side. Thus, it is configured to be connected to the second terminal 306 on the high voltage side.
[0055]
When this is shown by an equivalent circuit, as shown in FIG. 8, the six coil portions 301 constituting the center coil 111a are arranged in parallel between the common terminal 304 and the first terminal 305, and the common terminal 304 and the second terminal 305 are connected in parallel. In this circuit, three coil portions 301 constituting both side coils 111b and 111c are connected in parallel between the terminals 306, respectively.
[0056]
In an actual configuration, all of the lead wires 303 from both ends of each of the coil portions 301 are drawn for each coil portion 301, and 12 common terminals 304 are provided, and the other first and second terminals are provided. 6 lead wires 303 are led out to each of the terminals 305 and 306, which are bundled and connected to a terminal pin (or terminal socket) 307.
[0057]
Each of these coil portions 301 is wound around a cylindrical bobbin 300 made of an insulating material made of a nonmagnetic material. As shown in FIG. 9, the bobbin 300 has a frame shape, for example, a substantially U-shaped wire guide 310, in which a space is provided inside the bobbin main body 308 formed in a substantially cylindrical shape so that the wire 309 is passed through the bobbin body 308. Is formed in the axial direction. A pair of frame-like, for example, L-shaped wire guides 311 are similarly formed in the axial direction inside the bobbin main body 308 facing the wire guide 310 so as to be symmetric when viewed from the wire guide 310. .
[0058]
On the inner wall surface of the bobbin main body 308 in the middle, preferably the central portion of the pair of L-shaped wire guides 311, ribs 312 projecting radially in the center direction from the inner wall surface are formed in the axial direction of the bobbin main body 308. Further, a pair of ribs 312 is formed on both sides of the U-shaped wire guide 310 in the same manner. Since the rib 312 has a mold structure for integrally forming the bobbin 300, it is necessary to form a taper on the inner surface of the bobbin body 308 in the drawing direction. Since it is difficult to fix the fitting position in the surface contact state, it is necessary to fix the position between the two. Therefore, three or more locations are required on the circumference inside the bobbin main body 308 for accurate positioning, and the woven angle between the centers of the adjacent ribs 312 is set to be less than 180 °. The height of the rib 312 is also set to be less than the diameter of the electric wire 309 with respect to the maximum inner diameter portion of the bobbin main body 308. Since the rib 312 does not have a large area at the tip of the rib 312, it does not become an obstacle when the mold is pulled out.
[0059]
The rib 312 can be sharpened without flattening the tip, or can be configured as a dot or a line. When configured in this way, it becomes possible to exert stronger elasticity when the holder is mounted. In addition to being able to absorb molding errors, it is also possible to fix them firmly using this elasticity.
[0060]
Further, when the electric wire 309 is wound around the outer peripheral surface of the bobbin main body 308, the both ends of the bobbin main body 308 are radially developed at predetermined intervals in the outer peripheral direction so that the electric wire 309 does not fall off from the bobbin main body 308. A plurality of flanges 313 are formed. As shown in FIG. 10 when the bobbin main body 308 is viewed from one side and FIG. 11 when viewed from the other side, the flange 313 is formed at each end when viewed from one end surface side and the other end surface side. The flanges 313 are formed so as not to overlap each other so that they can be seen through each other. Such an arrangement of the flanges 313 is a device for solving the problem of the mold drawing direction when the bobbin 300 is formed.
[0061]
The flange 313 is disposed at least at one place on one side, and when the flange 313 is formed by one piece, the gap portion of the flange 313 is formed so that the gap portion not provided with the flange 313 is less than 180 °. It is necessary to set the length in the outer peripheral surface direction and take into consideration that the wound electric wire 309 does not come off the outer periphery of the bobbin main body 308. In addition, when a plurality of flanges 313 are arranged in the outer circumferential direction, they are arranged at a predetermined interval and are shifted so that the flanges 313 formed at both ends of the bobbin body 308 do not overlap with each other in the axial direction. Thus, by configuring the mold so that the mold can be punched in the axial direction of the bobbin 300, the structure of the mold can be simplified and the manufacturing cost of the mold can be reduced.
[0062]
A groove portion 314 is provided in a radial direction on the end surface of the bobbin main body 308 at the intermediate portion of the flange 313 so as to connect the inner and outer surfaces of the bobbin main body 308. The groove portion 314 has an L-shaped wire guide 311 on one end surface. It is provided at a position facing it and on the other end face at a position facing the U-shaped wire guide 310. In other words, the flange 313 is provided on both sides of the groove 314. When the electric wire 309 is wound around the outer peripheral surface of the bobbin main body 308, the groove portion 314 is formed by using the lead wire 315 at the start and end of winding of the electric wire 309, and the lead wire 315 on the lead-out direction side from the bobbin main body 308 as the groove portion. A lead line 315 on the inner side through 314 and opposite to the lead-out direction is drawn out in the same lead-out direction through the groove 314 and the wire guide 310.
[0063]
The groove 314 is formed on both sides of the groove 314 while preventing the electric wire 309 drawn inside the bobbin main body 308 from being caught between the bobbin main bodies 308 when the adjacent bobbin main bodies 308 are brought into contact with each other. Since the flange 313 serving as a guide for the electric wire 309 serves as a guide for the electric wire 309, it also serves as an efficiency of the winding work and prevents the electric wire 309 from coming off when the winding is completed. When the groove 314 is formed at a position of ± 90 ° or less with respect to the space inside the bobbin main body 308 from which the electric wire 309 is inserted, the electric wire 309 is effectively provided in a gap portion through which the electric wire 309 passes. Since it can be guided, it is preferably formed within ± 90 °.
[0064]
When the bobbin 300 configured in this way is viewed from the direction of the respective end surfaces, each end surface has a symmetrical shape with the axis as the center. The bobbin 300 having the same shape is used as it is even when, for example, the winding direction is reversed, or when the bobbin 300 is sequentially fitted on the holder with the same potential portion facing each other. Therefore, it is sufficient to prepare a small number of types of bobbins 300, and mass production is possible.
[0065]
In this way, each coil part 301 configured so that the wire 309 is wound around the outer peripheral surface of the bobbin main body 308 and the lead wire 315 portion is in the same direction is sequentially fitted and mounted on the outer periphery of the holder elongated in the axial direction. Thus, the coil 111 is configured.
[0066]
As shown in FIG. 12, the holder 319 is fitted with a wire guide 310 provided on the bobbin main body 308 at the bottom portion facing the center protruding portion 320 and having a substantially convex cross section at the center portion. It has a tetrapot-shaped core body part 322 formed with a recessed part 321 deeper than the height, and further curves the outer surface that is connected to the side surfaces of the convex part 323 on both sides of the recessed part 321 and is spaced apart from the central projecting part 320. The fan-shaped side wall portion 324 is integrally provided. Then, when the bobbin main body 308 is fitted, a part of the side wall 324 is cut away so that the L-shaped wire guide 311 in the bobbin main body 308 does not come into contact, thereby forming a flat portion 325 for escape. . A screw groove 326 for fitting the cap 302 for fixing the coil main body 308 on the holder 319 is provided on the outer peripheral portion of both ends of the core body portion 322 or the outer periphery of the side wall portion 324.
[0067]
As shown in FIG. 6, twelve bobbins 300 around which the electric wires 309 are wound are sequentially fitted to the holder 319 and both ends are fixed by caps 302. The bobbins 300 having the coil portions 301 wound so that the winding directions are alternately reversed are sequentially arranged, and the directions of the currents flowing through the coil portions 301 are all the same. Therefore, there are two types of winding methods for the winding direction of the electric wire 309. In order to distinguish the winding direction, for example, in the case of right-handed winding, the groove portion 314 on the left side in FIG. In the case of left-handed winding, the right groove 314 is used.
[0068]
When the bobbin 300 in which the electric wire 309 is sequentially wound is attached to the holder 319 in this way, the gap between the inner diameter portion of the bobbin 300 and the outer surface of the holder 319 sets the height of the rib 312 to be less than the diameter of the electric wire 309. Therefore, when the bobbin 300 is fitted into the holder 319, the electric wire 309 is not sandwiched between the bobbin main body 308 and the holder 319. When the bobbin main body 308 is fitted to the holder 319, as shown in FIG. 13, an axial direction is provided between the holder 319 and the bobbin 300 below the left and right wire guides 311 and above the U-shaped wire guide 310. A gap portion 330 is formed in a row. In this gap portion 330, a lead wire 315 of an electric wire 309 wound around another bobbin 300 that is sequentially connected other than the bobbin 300 around which the electric wire 309 is wound is disposed and led out in the same direction. . For example, in the gap portion 330 on the left side in the figure, a leader line 315 group connected to the first terminal 305 shown in FIG. 7 is provided, and in the gap portion 330 on the right side, the leader line 315 is also connected to the second terminal 306. A group of leader lines 315 connected to the common terminal 304 are arranged in the lower gap portion 330.
[0069]
Thus, by arranging the bobbin 300 and the holder 319 so as to be coaxial, it is possible to assemble the coil unit 301 with high accuracy and efficiency, and to reduce the error. Further, bobbins 300 each wound with an electric wire 309 are fitted on the outer peripheral surface of the holder 319 to form a coil 111, and the entire coil 111 is covered with a heat-resistant insulating cylinder 331 and mounted in the heat roller 101 for fixing. Configure the device. This heat-resistant insulating cylinder 331 is for improving the insulation resistance between the electric wire 309 and the heat roller 101. Even if the electric wire 309 is damaged and the insulation is deteriorated, the electric insulation between the electric wire 309 and the heat roller 101 is reduced. It can be omitted as long as it is installed to prevent unforeseen circumstances such as discharge from occurring and sufficient insulation resistance can be maintained. In this way, the holder 319 and the bobbin 300 are coaxially arranged, and the distance between each coil portion 301 and the heat roller 101 can be kept substantially constant, so that temperature unevenness of the heat roller 101 is reduced. Is possible.
[0070]
【The invention's effect】
As described above, according to the present invention, a magnetic field generator for induction heating, which is excellent in practicality and reliability free from fixing problems due to various paper sizes, is easy to manufacture and has high workability, and the same are used. A fixing device can be provided.
[Brief description of the drawings]
FIG. 1 is a diagram showing an internal configuration of an embodiment.
FIG. 2 is a diagram illustrating a configuration of a fixing device in the embodiment.
FIG. 3 is a block diagram illustrating a control circuit of the electronic copying machine according to the embodiment.
FIG. 4 is a configuration diagram of an electric circuit in the fixing device according to the embodiment.
FIG. 5 is a diagram illustrating a relationship between output power of each series resonance circuit and a frequency for exciting each series resonance circuit in the fixing device according to the embodiment.
6 is a diagram showing an outline of a magnetic field generator (coil) 111. FIG.
FIG. 7 is a configuration diagram of an electric circuit of the magnetic field generator.
FIG. 8 is a configuration diagram of an equivalent circuit of the magnetic field generator.
FIG. 9 is a perspective view showing a bobbin constituting the magnetic field generator.
FIG. 10 is a plan view of the bobbin as seen from one end surface side.
FIG. 11 is a plan view of the bobbin as seen from the other end surface side.
FIG. 12 is a perspective view showing a holder constituting the magnetic field generator.
FIG. 13 is a diagram illustrating a specific configuration of the fixing device according to the embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Main body, 20 ... Photosensitive drum, 100 ... Fixing device, 101 ... Heating roller, 102 ... Pressure roller, 111a, 111b, 111c ... Coil, 120 ... High frequency generating circuit, 121 ... Rectifier circuit, 122 ... Switching circuit, 123, 124, 125 ... capacitor, 126 ... transistor (switching element), 140 ... controller, 141 ... oscillation circuit, 142 ... CPU, 150 ... current detection circuit, 171 ... coil, 300 ... bobbin, 301 ... coil part, 308 ... Bobbin body, 309 ... electric wire, 310 ... electric wire guide, 311 ... electric wire guide, 312 ... rib, 313 ... flange, 314 ... groove, 315 ... leader

Claims (7)

A heated member;
A magnetic field generator for generating and heating an eddy current in the heated member;
A pressure member that rotates with the heated member while in contact with the heated member, and the magnetic field generator has a cylindrical shape around which an electric wire forming a coil portion is wound. An induction heating fixing device having a bobbin body and flanges formed at both ends of the bobbin body, wherein the flanges at both ends are disposed at different positions in the axial direction of the bobbin body. . 2. The induction heating fixing device according to claim 1, wherein the bobbin main body has grooves formed radially at both ends thereof to connect the inner and outer surfaces, and the flanges are disposed on both sides of the grooves. The at least three frame-shaped electric wire guides are formed on the inner surface of the bobbin main body, and the remaining electric wire guides are arranged symmetrically with respect to one selected electric wire guide. The induction heating fixing device according to any one of 1 and 2. The induction heating fixing device according to claim 3, wherein the groove is positioned within ± 90 ° with respect to the wire guide. 5. The induction heating according to claim 1, wherein the end surfaces of the bobbin main body are formed symmetrically with respect to an axis, and both end surfaces are formed asymmetrically. Fixing device. A heated member;
A magnetic field generator for generating and heating an eddy current in the heated member;
A pressure member that rotates with the heated member while in contact with the heated member, and the magnetic field generator has a cylindrical shape around which an electric wire forming a coil portion is wound. A guide having a bobbin main body and a plurality of ribs formed on the inner peripheral surface of the bobbin main body and projecting inward, and a holder abutting on the rib and positioned in the bobbin main body. Heat fixing device. The plurality of ribs are disposed at three positions on the inner surface of the bobbin main body, and an arrangement angle between adjacent ribs among the plurality of ribs is set to be less than 180 °. Item 7. The induction heating fixing device according to Item 6.

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