JP2004294695A - Fixing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device that has excellent practicality and high reliability by obtaining, at high production efficiency, an induction coil that saves more energy during heat generation of a heat roller. <P>SOLUTION: A coil guide 137 in the form of a helical groove is formed on the outer circumferential face of a bobbin 117. A winding wire 116 is wound along the coil guide 137 on the bobbin 117. Thus, a coil unit 119 having a coil 118 of a specified number of loops is always obtained. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD 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 toner image on sheet paper.
[0002]
[Prior art]
2. Description of the Related Art An electrophotographic copying machine, a printer, and the like include a fixing device that heats and fixes a toner image formed on a sheet of paper. As one of the fixing devices, a sheet roller is provided between a heating roller and a pressure roller that is in pressure contact with the heating roller, and the sheet paper is sandwiched between the two rollers. There is a fixing roller device for fixing the toner image by heating and pressing. In recent years, this fixing roller device has been required to promote energy saving when heat roller generates heat. For this reason, the development of a device that can obtain the heat generated by the heating roller with high thermal efficiency and shorten the warm-up time is being promoted.
[0003]
As a device for saving energy when the heat roller generates heat, a device that provides an induction coil inside the heat roller to generate an eddy current in the heat roller and self-heats the heat roller by Joule heat due to the eddy current has been studied. . Further, in a fixing device using such an induction coil, there is a device that uses a plurality of induction coils to heat only a necessary region of the heating roller in order to induce heat generation of the heating roller for each region corresponding to the transfer paper width. (For example, see Patent Document 1)
[0004]
[Patent Document 1]
JP 2001-212165 A (pages 3 and 4; FIG. 1)
However, Patent Literature 1 and the like simply induce heat generation of a heating roller by a plurality of induction coils divided according to a transfer paper width, and do not consider reduction of energy loss due to winding of the induction coil. . On the other hand, in order to further reduce energy consumption of a device for inducing heat generation of a heating roller by using an induction coil, it is required to further reduce, for example, copper loss caused by winding of the induction coil and iron loss due to the material of the heating roller. Therefore, there is a demand for the practical use of a fixing device that obtains good fixing with higher efficiency.
[0005]
[Problems to be solved by the invention]
Therefore, the present invention is to solve the above-mentioned problem, and to provide an induction coil for further saving energy at the time of heat generation of a heating roller with high production efficiency, thereby providing a highly practical and highly reliable fixing device. Aim.
[0006]
[Means for Solving the Problems]
Means for Solving the Problems As a means for solving the above problems, a hollow heat generating member that contacts a recording medium and generates heat by generating eddy current, and a coil guide provided on the inside of the hollow of the heat generating member and on an outer peripheral surface thereof is provided. A coil unit formed by winding a predetermined number of turns around an outer peripheral surface of the coil support member along the coil guide, the coil unit generating the eddy current in the heat generation member, and contacting the heat generation member And a pressure member for nipping and transporting the recording medium with the heat generating member at a predetermined pressure.
[0007]
According to another aspect of the present invention, there is provided a heating roller that contacts a recording medium and generates heat by generating an eddy current; a bobbin provided inside the heating roller and having a coil guide on an outer peripheral surface; A coil unit is formed by winding a winding around the outer peripheral surface of the bobbin a predetermined number of times along a coil guide. The coil unit generates the eddy current on the heating roller. And a pressure roller for nipping and transporting the pressure roller together with the heating roller.
[0008]
According to another aspect of the present invention, there is provided a hollow heat generating member that contacts a recording medium and generates heat by generating an eddy current, and a coil guide provided on the inside of the hollow of the heat generating member. And a plurality of coil units each having a coil formed by winding a predetermined number of turns around the outer peripheral surface of the coil supporting member along the coil guide, and generating the eddy current in the heat generating member. A plurality of coil unit groups to be driven, and a pressing member that contacts the heat generating member and nips and conveys the recording medium with the heat generating member at a predetermined pressure.
[0009]
According to another aspect of the present invention, there is provided a heating roller that contacts a recording medium and generates heat by generating an eddy current; a bobbin provided inside the heating roller and having a coil guide on an outer peripheral surface; A plurality of coil units having a plurality of coil units each having a coil formed by winding a winding around the outer peripheral surface of the bobbin a predetermined number of times along a coil guide, and generating the eddy current in the heating roller; A pressure roller that contacts the heating roller and nips and conveys the recording medium with the heating roller at a predetermined pressure.
[0010]
With the above configuration, the present invention suppresses variations when winding the winding around the coil supporting member, and aims to improve the productivity of the induction coil by easily obtaining a high-precision coil formed by precisely winding the winding a predetermined number of times, An object of the present invention is to reduce the manufacturing cost and commercialize a highly reliable fixing device using an induction coil.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention is to divide an induction coil excited at the same resonance frequency into a plurality of coil units in order to reduce energy loss caused by winding of the induction coil. By dividing the induction coil into a plurality of coil units, the length of the winding of each coil unit is shortened to reduce energy loss. At this time, the coil units divided into parts are excited in parallel at the same resonance frequency. Further, the present invention aims to reduce the current by setting the frequency of the high-frequency power for generating a magnetic field in the induction coil to be higher, thereby making the winding thin and reducing the energy loss.
[0012]
Hereinafter, the present invention will be described in detail with reference to the embodiments shown in FIGS. FIG. 1 is a schematic configuration diagram showing a composite electronic copying machine 1A according to an embodiment of the present invention. A transparent document table (glass plate) 2 for mounting a document is provided on the upper surface of the main body 1, and is placed on the document table 2 by turning on an exposure lamp 5 provided on a carriage 4. The document D is exposed.
[0013]
When the light reflected from the document D by the exposure lamp 5 is projected on a CCD (Charge Coupled Device) sensor 10 which is a photoelectric conversion device, the CCD sensor 10 photoelectrically converts the received optical signal into an image signal composed of an electric signal. To output a signal. The image signal output from the CCD 10 is converted into a digital signal in a signal processing unit 73 to be described later, subjected to data processing as appropriate, and supplied to the laser unit 27. The laser unit 27 emits a laser beam B according to an input signal.
[0014]
The document table 2 on the upper surface of the main body 1 is covered by an automatic document feed unit 40. A control panel 80a for setting image forming conditions and the like is provided on the upper surface of the main body 1. The control panel 80a includes a liquid crystal display unit 14 of a touch panel type, a numeric keypad unit 15 for inputting numerical values, a copy key 17, and the like.
[0015]
A photosensitive drum 20 is rotatably provided at a substantially central portion in the main body 1. Around the photosensitive drum 20, a charging device 21, a developing unit 22, a transfer device 23, a peeling device 24, a cleaner 25, and a static eliminator 26 are sequentially arranged. , A toner image is formed on the photosensitive drum 20. Further, the toner image formed on the photosensitive drum 20 is transferred onto a sheet S as a recording medium. The toner image T formed on the sheet S is heated and pressed by a fixing device 100 described later. After fixing, the sheet S is discharged to a tray 38 via a discharge roller 37.
[0016]
Below the photosensitive drum 20 of the main body 1, a plurality of paper feed cassettes 30 for storing sheet paper S are provided. While the sheet S reaches the transfer unit 23 from the sheet cassette 30, the sheet S is taken out from the sheet cassette 30 and fed to the transfer unit 23, and the sheet S fed by the sheet supply unit 31 is fed. Roller 32 that transports the toner image in synchronization with the toner image formed on the photosensitive drum 20 is provided.
[0017]
Next, the fixing device 100 will be described in detail. FIG. 2 is a schematic configuration diagram of the fixing device 100. A heating roller 101 as a heating member and a pressure roller 102 as a pressure member are provided at positions vertically sandwiching the sheet S in the conveyance path of the sheet S. The pressure roller 102 is in contact with the peripheral surface of the heating roller 101 while being pressed by a pressure mechanism (not shown). The contact portion between the rollers 101 and 102 has a constant nip width.
[0018]
The heating roller 101 is formed by molding a conductive material such as iron into a cylindrical shape and coating the outer peripheral surface of the iron with Teflon or the like, and is driven to rotate in the direction of the arrow m in FIG. The pressure roller 102 rotates in the direction of arrow q in FIG. When the sheet S passes through a contact portion having a fixed nip width between the heating roller 101 and the pressure roller 102, and the sheet S receives heat from the heating roller 101, the toner image T on the sheet S is formed. Is fixed on the sheet S by heating and pressing.
[0019]
Around the heating roller 101, a peeling claw 103 for peeling the sheet 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.
[0020]
Inside the heating roller 101, an induction coil 111 composed of a first induction coil 111a and a second induction coil 111b as a coil unit group and having a substantially cylindrical outer peripheral shape is provided coaxially with the heating roller 101. In the induction coil 111, the second induction coil 111b is disposed at both sides of the first induction coil 111a with the first induction coil 111a at the center. The heating roller 101 excites only the first induction coil 111a during normal fixing to perform fixing, and fixes the first induction coil 111a and the second induction coils 111b on both sides of the first induction coil 111a when fixing to a large-sized sheet S. All are excited and fixed.
[0021]
The outer circumference of the induction coil 111 has a distance of about 2 mm from the inner circumference of the heating roller 101 via the insulating cover 106. The induction coil 111 generates a high-frequency magnetic field for induction heating by applying high-frequency power. When the induction coil 111 generates a high-frequency magnetic field, an eddy current is generated in the heating roller 101, and the heating roller 101 generates heat by Joule heat generated by the eddy current.
[0022]
Next, the structure of the induction coil 111 will be described in detail. The induction coil 111 is provided with a holder 114 having substantially the same length as the heating roller 101, and a holder 114. No. 1 to No. Twelve coil units 119 divided into twelve parts are inserted, and both ends are fixed with screw rings 115 to assemble and mold. As shown in FIG. 6, the induction coil 111 sets a coil unit α119a and a coil unit β119b, which will be described later, as Nos. 4 to No. 4 A first induction coil 111a in which a total of six coils are alternately arranged adjacent to each other, and a coil unit γ119c and a coil unit δ119d described below are No. No. 1 to No. No. 3 and no. 10 to No. And a second induction coil 111b in which up to 12 are alternately arranged in total of three.
[0023]
The holder 114 is formed by molding an insulating resin into a mold. On the surface of the holder 114, first to third passages 114a, 114b, 114c for forming a space-like passage for passing the winding 116 of the induction coil 111 with the induction coil 111, and a coil supporting member. First to third slits 114e, 114f, 114g for positioning a certain bobbin 117 are formed. The holder 114 inserts and supports 12 coil units 119 each having a coil 118 formed by winding a winding 116 around a bobbin 117 a predetermined number of times.
[0024]
The first to third passages 114a to 114c are separately guided so as to prevent contact between the start end and the end of the winding 116 of the coil 118 of the plurality of coil units 119 inserted into the holder 114. Further, the first and second passages 114a and 114b are separated so that the leading end side of the winding 116 of the coil 118 is guided separately by the first induction coil 111a and the second induction coil 111b. In each of the passages 114a to 114c, the windings 116 drawn from the plurality of coil units 119 increase in a bundled state.
[0025]
The coil unit 119 includes a coil unit α 119a with 44.5 turns of the coil 118 and a right-handed coil unit, a coil unit β 119b with 44.5 turns of the coil 118 and a left-handed coil unit, and a left-handed coil unit with 48.5 turns. There are four types of a coil unit γ 119c and a coil unit δ 119d which has 48.5 turns and a right-handed coil unit δ 119d.
[0026]
The coil units 119 are arranged in such a direction that the potential differences between the windings 116 of the adjacent coil units 119 are the same. That is, the second induction coils 111b at both ends in FIG. 6 are sequentially arranged such that the coil start ends 118a of about 1 kV and the coil end 118b of 0V of the coil units γ119c and δ119d are adjacent to each other. Similarly, the first induction coil 111a in the center of FIG. 6 is also sequentially arranged such that the coil start ends 118a and the coil end ends 118b of the coil units α119a and β119b are adjacent to each other. The same applies between the first induction coil 111a and the second induction coil 111b.
[0027]
The bobbin 117 of the coil unit 119 is formed by molding an insulating resin into a mold. First to third ribs 117a, 117b, and 117c guided by the first to third slits 114e, 114f, and 114g of the holder 114 protrude from the inner periphery of the bobbin 117. By inserting the first to third ribs 117a, 117b, 117c of the bobbin 117 into the first to third slits 114e, 114f, 114g of the holder 114, the holder 114 and the bobbin 117 are positioned coaxially.
[0028]
Further, on the inner periphery of the bobbin 117, first to third winding guides 117e, 117f, and 117g, which are pipe members for inserting one side of the winding 116 of each coil unit 119, are formed.
[0029]
The first and second winding guides 117 e and 117 f are windings 116 on the side of the high potential coil starting end 118 a of the coil 118 wound around the outer peripheral surface of the bobbin 117, and are guided through the inner peripheral side of the bobbin 117. The induction coil 111 is easy to assemble by passing the winding 116 guided toward the end of the coil 111. The third winding guide 117g is a winding 116 on the coil end 118b side of the zero potential of the coil 118 wound around the outer peripheral surface of the bobbin 117 and passes through the inner peripheral side of the bobbin 117 toward the end of the induction coil 111. The induction coil 111 is easy to assemble by passing a winding 116 guided to the coil. The first to third winding guides 117e to 117g are formed at positions that are line-symmetric about the dotted line CC ′ in FIG.
[0030]
As shown in FIG. 9, both ends of the first to third winding guides 117e to 117g are regulated so as to be separated from the side surfaces 127 and 128 of the bobbin 117 by the gap s1 or s2. The ends of the first to third winding guides 117e to 117g have at least a first or second groove 127f, 127g or a third groove 128f described later inside the both side surfaces 127, 128 of the bobbin 117. The position is regulated so that The first to third grooves 127f, 127g, and 128f are for preventing the winding 116 from being sandwiched between the adjacent bobbins 117 when the plurality of coil units 119 are sequentially adjacent. The gap s1 or the gap s2 prevents the winding 116 from being sandwiched between the adjacent first to third winding guides 117e to 117g, similarly to the first to third grooves 127f, 127g, and 128f. is there.
[0031]
That is, the depth of the grooves 127f, 127g, and 128f only needs to be equal to the diameter of the winding 116, and therefore, the gap s1 or s2 only needs to be equal to or larger than the diameter of the winding 116. If the grooves 127f, 127g, and 128f are located at the same position on the adjacent bobbins 117 due to the arrangement of the coil units 119, the depth of the groove may be １ ／ of the diameter of the winding 116. The gap s2 may be at least １ ／ of the diameter of the winding 116.
[0032]
However, if the length of the first to third winding guides 117e to 117g is too short, when inserting the coil unit 119 into the holder 114, the windings cannot be guided sufficiently, and the winding It is preferable that the first to third winding guides 117e to 117g have a length of at least 1/4 or more, since there is a risk of being pinched between the bobbin 117 and the bobbin 117.
[0033]
On the front side 127 of the bobbin 117, first to fifth flanges 127a to 127e are formed to make it difficult for the coils 118 wound around the bobbin 117 to come off. On the back side 128 of the bobbin 117, similarly, Sixth to ninth flanges 128a to 128d for preventing the coil 118 from coming off easily are formed. The flanges 127a to 127e of the front side surface 127 of the bobbin 117 and the flanges 128a to 128d of the back side surface 128 are formed out of phase when viewed from the axial direction.
[0034]
Between the first flange 127a and the second flange 127b of the front side surface 127 of the bobbin 117, or between the second flange 127b and the third flange 127c, the winding 116 on the coil start end 118a side is inserted into the bobbin 117. First or second grooves 127f, 127g leading to the first or second winding guides 117e, 117f, respectively, are formed. Between the seventh flange 128b and the eighth flange 128c on the back side surface 128 of the bobbin 117, a third groove for guiding the winding 116 on the coil terminal end 118b side to a third winding guide 117g on the inner periphery of the bobbin 117. 128f are formed.
[0035]
A coil guide 137 formed of a spiral groove is formed on the outer peripheral surface of the bobbin 117. The coil guide 137 is provided to wind the winding 116 around the bobbin 117 a specified number of times. The length of the coil guide 137 is formed according to the number of turns of the coil 118 from the coil unit α 119a to the coil unit δ 119d. That is, if the winding 116 is wound around the bobbin 117 along the coil guide 137, the coil 118 is always formed in the prescribed number of turns of 44.5 or 48.5.
[0036]
Next, a control system of the composite type electronic copying machine 1A will be described with reference to a block diagram shown in FIG. The scan CPU 70, the control panel CPU 80, and the 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, and controls a copy mode according to the operation of the copy key 17, and a printer according to an image input to a network interface 59 described later. A mode control unit and a FAX (facsimile) mode control unit in accordance with image reception by a facsimile transmission / reception unit 60 described later are provided.
[0037]
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 transmitting / receiving unit 60 are connected to the main CPU 50. I have. The page memory controller 56 controls writing and reading of image data to and from the page memory 57. The image data bus 61 connects 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 facsimile transmission / reception unit 60 to one another.
[0038]
The net 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 network 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.
[0039]
The FAX transmitting / receiving unit 60 is connected to the telephone line 210 and functions as a facsimile mode receiving unit that receives an image (image data) transmitted by facsimile through the telephone line 210.
[0040]
The scan CPU 70 includes a ROM 71 for storing a control program, a RAM 72 for storing data, a signal processing unit 73 for processing the signal output of the CCD 10 and supplying the signal output to the image data bus 61, a CCD driver 74, a scan motor driver 75, an exposure lamp 5, an automatic document feeder 40, a plurality of document sensors 11, and the like. The CCD driver 74 drives the CCD 10. The scan motor driver 75 drives a scan motor 76 for driving the carriage 4. The automatic document feeder 40 has a document sensor 43 for detecting a document D set on a tray 41 and its size.
[0041]
The control panel CPU 80 is connected to a touch panel type liquid crystal display section 14, a numeric keypad 15, an all reset key 16, a copy key 17, and a stop key 18 of the control panel.
[0042]
The print CPU 90 is connected to a ROM 91 for storing a control program, a RAM 92 for storing data, a print engine 93, a sheet paper transport unit 94, a process unit 95, and a fixing device 100. The print engine 93 is configured by a drive circuit of the laser unit 27 and the like. The sheet paper transport unit 94 includes a sheet paper transport mechanism extending from the paper feed cassette 30 to the tray 38 and a drive circuit therefor. The process unit 95 includes the photosensitive drum 20 and its peripheral parts.
[0043]
A print section for printing the image processed by the image processing section 55 on the sheet S is mainly composed of the print CPU 90 and its peripheral configuration.
[0044]
Next, the heat generation control of the fixing device 100 will be described with reference to an electric circuit diagram shown in FIG. The induction coil 111 is connected to the high frequency generation circuit 120. A temperature sensor 112 for detecting the temperature at the center of the heating roller 101 and a temperature sensor 113 for detecting the temperature at one end of the heating roller 101 are connected to the print CPU 90. The print CPU 90 has a function of connecting to and controlling a drive unit 160 for rotationally driving the heating roller 101, and also includes a first series resonance circuit (output power P1) described below, which includes a first induction coil 111a as a component. A function of issuing a P1 / P2 switching signal for specifying an operation and an operation of a second series resonance circuit (output power P2) described later, which includes the second induction coil 111b as a component, and an output power P1 of each resonance circuit. A function is provided for controlling P2 in accordance with the detected temperatures of the temperature sensors 112 and 113.
[0045]
The high frequency generation circuit 120 generates high frequency power of about 1 to 3 MHz 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. Rectifier circuit 121 rectifies the AC voltage of commercial AC power supply 130. The switching circuit 122 forms a first series resonance circuit with the first induction coil 111a and the capacitors 123 and 125, and forms a second series resonance circuit with the second induction coil 111b and the capacitors 124 and 125. Is selectively excited by a switching element, for example, a transistor 126 such as an FET.
[0046]
The first series resonance circuit has a resonance frequency f1 determined by the inductance L1 of the first induction 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 second induction coil 111b, the capacitance C2 of the capacitor 124, and the capacitance C3 of the capacitor 125.
[0047]
The transistor 126 is turned on and off by the controller 140 in accordance with the 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 issues a drive signal of 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.
[0048]
(1) When the operation of the first series resonance circuit (only the first induction coil 111a is used) is specified by the P1 / P2 switching signal from the print CPU 90, the first series resonance circuit is placed near the resonance frequency f1. Control means for sequentially (alternatingly) exciting at a plurality of frequencies, for example, (f1-Δf) and (f1 + Δf) shown in FIG.
[0049]
(2) When the operation of the first and second series resonance circuits (using all the first and second induction coils 111a and 111b) is specified by the P1 / P2 switching signal from the print CPU 90, the first and second signals are used. Control means for sequentially exciting the two-series resonance circuit at a plurality of frequencies near the respective resonance frequencies f1 and f2, for example, (f1-Δf), (f1 + Δf), (f2-Δf), and (f2 + Δf) shown in FIG.
[0050]
When manufacturing the induction coil 111 for electromagnetically inducing the heating roller 101 of the composite type electronic copying machine 1A as described above, first, the holder 114 and the bobbin 117 are integrally formed by a mold using an insulating resin as a raw material. The bobbin 117 is formed of four types: a bobbin in which the winding 116 is wound 44.5 times clockwise or counterclockwise, and a bobbin in which the winding 116 is wound 48.5 times clockwise or counterclockwise. After the integral molding, the coil guide 137 is formed on the outer peripheral surface of the bobbin 117 by machining using a lathe after the slide integral molding. The coil guide 137 is formed to have a length for winding the winding 116 around the bobbin 117 44.5 times and to have a length for winding the winding 116 around the bobbin 117 48.5 times.
[0051]
Next, the coil 118 is formed by winding the winding 116 around the bobbin 117 clockwise 44.5 times along the coil guide 137 to form the coil unit α 119a. Similarly, a coil unit β119b having a left-handed coil of 44.5 turns 118, a coil unit γ119c having a left-handed coil of 48.5 turns 118, and a coil unit δ119d having a right-handed coil of 48.5 turns 118 are formed. I do.
[0052]
This coil 118 can reliably obtain a coil having a desired number of turns only by winding the coil along the coil guide 137, so that rewinding work can be prevented. The coil 118 wound around the bobbin 117 is restricted on both sides by flanges 127a to 127e and 128a to 128d, so that it is hard to come off.
[0053]
The winding 116 on the coil start end 118a side after the coil winding passes through the first or second groove 127f or 127g, respectively, and the first or second passage formed between the holder 114 and the induction coil 111. It passes through 114a and 114b. The winding 116 on each coil end 118b side is passed through a third groove 128f to a third passage 114c formed between the holder 114 and the induction coil 111.
[0054]
The first to fourth types of coil units 119a to 119d are sequentially mounted on the holder 114 from the direction of the arrow r as shown in FIG. At this time, the first to third ribs 117a, 117b, 117c formed on the bobbin 117 of the coil units 119a to 119d are guided and positioned by the first to third slits 114e, 114f, 114g of the holder 114. .
[0055]
According to the arrangement of the coil units 119, when the coil start end 118a of the coil unit 119 is located on the rear side in the direction of the arrow r in FIG. 7 and is guided to the end of the induction coil 111 through the inner peripheral side of the bobbin 117, the winding 116 Is housed in the first or second groove 127f or 127g, passes through the first or second winding guide 117e or 117f on the inner peripheral surface of the bobbin 117, and is formed between the holder 114 and the bobbin 117. It is guided to the first or second passages 114a and 114b and guided to the end of the induction coil 111. Similarly, when the coil end 118b of the coil unit 119 is on the far side in the direction of the arrow r in FIG. 7 and is guided to the end of the induction coil 111 through the inner circumference of the bobbin 117, the winding 116 is the third winding. After being accommodated in the groove 128f and further passing through the third winding guide 117g on the inner peripheral surface of the bobbin 117, it is guided to the third passage 114c formed between the holder 114 and the bobbin 117, and is guided to the end of the induction coil 111. Be guided.
[0056]
Accordingly, when the coil units 119 are sequentially mounted on the holder 114, the windings 116 on the rear side in the mounting direction are not damaged by being sandwiched between the holder 114 and the bobbin 117. 3 can be safely guided toward the end of the induction coil 111 through one of the passages 114a to 114c.
[0057]
In this manner, No. No. 1 to No. The induction coil 111 is formed by inserting the twelve coil units 119 up to twelve and fixing both ends with the screw rings 115. Then, after covering the induction coil 111 with the insulating cover 106, it is assembled into the heating roller 101 to complete the heating roller 101.
[0058]
In the fixing device 100 having the heating roller 101 thus configured, when a driving signal having the same frequency (or a frequency close to the resonance frequency f1) of the first series resonance circuit of the high frequency generation circuit 120 is generated from the oscillation circuit 141, The transistor 126 is switched by the driving signal, and the first series resonance circuit is excited. Due to the excitation of the first series resonance circuit, the first induction coil 111a is no. 4 to No. 4 The current in the direction of arrow u in FIG. 3 flows through the coil units 119 up to 8, and a high-frequency magnetic field is generated from the first induction coil 111a. The high-frequency magnetic field generates an eddy current in the central portion of the heating roller 101 in the axial direction. The axial center of the heating roller 101 self-heats due to Joule heat due to the eddy current.
[0059]
In addition, when a driving signal having the same frequency (or a frequency close to the resonance frequency f2) of the second series resonance circuit of the high frequency generation circuit 120 is generated from the oscillation circuit 141, the fixing device 100 causes the transistor 126 to be switched by the driving signal. Then, the second series resonance circuit is excited. Due to the excitation of the second series resonance circuit, the second induction coil 111b is no. No. 1 to No. No. 3 and no. 10 to No. 3 flows in the coil units 119 up to 12, and a high-frequency magnetic field is generated from the second induction coil 111b. The high-frequency magnetic field generates an eddy current in the axial center portion of the heating roller 101. Joule heat generated by the eddy current causes both sides of the heating roller 101 in the axial direction to generate heat.
[0060]
As shown in FIG. 15, the output power P1 of the first series resonance circuit has a peak level when excited at the same frequency as the resonance frequency f1 of the first series resonance circuit. The pattern gradually decreases in a mountainous manner as the distance from the vehicle increases. Similarly, the output power P2 of the second series resonance circuit has a peak level when excited at the same frequency as the resonance frequency f2 of the second series resonance circuit, and peaks as the excited frequency moves away from the resonance frequency f2. The pattern gradually decreases.
[0061]
When the power of the composite electronic copying machine 1A having such a fixing device 100 is turned on, the fixing device 100 starts a warm-up operation, and the high-frequency operation is performed by the temperature sensors 112 and 113 until the entire length of the heating roller 101 reaches the ready temperature. The first and second series resonance circuits of the generation circuit 120 are both excited to generate a high-frequency magnetic field from both the first and second induction coils 111a and 111b, thereby generating an eddy current in the entire heating roller 101, The entire heating roller 101 self-heats with Joule heat due to the eddy current.
[0062]
In this case, a drive signal having two frequencies (f1−Δf) and (f1 + Δf) separated by a predetermined value Δf above and below the resonance frequency f1 of the first series resonance circuit of the high-frequency generation circuit 120 is actually generated by the oscillation circuit. 141, and a drive signal having two frequencies (f2−Δf) and (f2 + Δf) separated by a predetermined value Δf above and below the resonance frequency f2 of the second series resonance circuit of the high frequency generation circuit 120. Are sequentially output from the oscillation circuit 141.
[0063]
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 subsequently, the second series resonance circuit sandwiches the resonance frequency f2. It is excited sequentially at two frequencies (f2-Δf) and (f2 + Δf). By repeating the excitation for each frequency, the entire heating roller 101 generates heat.
[0064]
As shown in FIG. 15, the output power P1 of the induction 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) Also at the time of the excitation at, the value P1b is slightly lower than the peak level P1c. The output power P2 of the second induction coil 111b in the second series resonance circuit has a value P2a slightly lower than the peak level P2c at the time of excitation at the frequency (f2-Δf), and also has a peak at the time of excitation at the frequency (f2 + Δf). The value P2b is slightly lower than the level P2c.
[0065]
After the surface temperature of the heating roller 101 reaches the ready temperature, the excitation of the first and second induction coils 111a and 111b by the high frequency generation circuit 120 is repeatedly turned on / off to maintain a predetermined ready temperature. When a print operation is instructed from the control panel 80a during this ready state, the fixing device 30 generates heat in a necessary area of the heating roller 101 according to the instructed sheet paper S size.
[0066]
That is, at the time of fixing the A.4 size vertical sheet paper S, the oscillation circuit 141 of the high frequency generation circuit 120 causes the first series resonance circuit to operate at two frequencies (f1−Δf) and (f1 + Δf) sandwiching the resonance frequency f1. Excite sequentially. By the excitation of the first series resonance circuit, a high-frequency magnetic field is generated from the first induction coil 111a, and the central portion of the heating roller 101 in the axial direction is self-heated, thereby fixing the surface temperature of the central portion of the heating roller 101 in the axial direction. Set the temperature and start fixing. Thereafter, the excitation of the first induction coil 111a is repeatedly turned on and off, and the surface temperature of the central portion in the axial direction of the heating roller 101 is maintained at the fixing temperature, thereby fixing the toner image formed on the sheet paper S.
[0067]
After the fixing is completed, on / off of the excitation of the first and second induction coils 111a and 111b by the high frequency generation circuit 120 is repeated so as to maintain the entire heating roller 101 at a predetermined ready temperature. If the size of the sheet S for which the print operation has been instructed is large, the excitation of the first and second induction coils 111a and 111b by the high-frequency generation circuit 120 is repeatedly turned on / off, and the entire heating roller 101 is turned on. The self-heating causes the entire surface temperature of the heating roller 101 to be set to the fixing temperature, and the fixing is started. Thereafter, the excitation of the first and second induction coils 111a and 111b is repeatedly turned on / off to maintain the entire surface temperature of the heating roller 101 at the fixing temperature, thereby fixing the toner image formed on the sheet paper S. Do.
[0068]
According to this embodiment having the above-described configuration, when the induction coil 111 for achieving energy saving is manufactured, the winding 116 is always wound along the coil guide 137 formed in a spiral shape on the outer peripheral surface of the bobbin 117, so that it is always accurate. The coil 118 having the specified number of turns can be formed extremely easily and with high precision. Therefore, unlike the related art, there is no variation in the number of turns of the coil 118 or the necessity of rewinding the coil 118, so that desired heat generation of the heating roller 101 can be accurately and easily obtained, and reliability can be improved. Further, the production efficiency of the coil unit 119 can be improved, and the cost can be reduced by mass-producing the induction coil 111, and a fixing device using the induction coil which is excellent in practicality and reliability can be obtained.
[0069]
The present invention is not limited to the above-described embodiment, and can be variously changed in design. For example, the shape of the coil support portion is not limited, and the position of the flange and the groove is arbitrary. The length of the guide is also arbitrary. Furthermore, the number and size of the coil units constituting the coil unit group are not limited, and the number and size of the coil unit group are also arbitrary according to the distribution of the heat generating region of the heat generating member. It should be noted that the number of spatial passages through which the windings of the coils formed in the holder are passed is also arbitrary according to the number of coil unit groups.
[0070]
The material of the heat generating member may be stainless steel or the like as long as it has conductivity, but a material capable of reducing energy loss at the time of heat generation is preferable, and a winding material is also optional, but a material capable of reducing current loss is preferable. . The method of forming the coil guide on the outer peripheral surface of the coil support is not limited. Further, the frequency of the high-frequency power for generating a magnetic field in the coil unit group is not limited, and the resonance frequency for exciting each of the plurality of coil unit groups is also arbitrary.
[0071]
【The invention's effect】
As described above in detail, according to the present invention, a desired induction coil for achieving energy saving can be formed extremely easily and with high accuracy, and cost reduction can be achieved by mass production of the induction coil. Therefore, it is possible to provide a fixing device using an induction coil which is excellent in practicality and reliability.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing a multifunction electronic copying machine according to an embodiment of the present invention.
FIG. 2 is a schematic configuration diagram illustrating a fixing device according to an embodiment of the present invention.
FIG. 3 is a schematic perspective view showing an induction coil according to the embodiment of the present invention.
FIG. 4 is a schematic sectional view showing an induction coil according to the embodiment of the present invention.
FIG. 5 is a schematic perspective view showing a coil unit according to the embodiment of the present invention.
FIG. 6 is a schematic explanatory view showing an arrangement of coil units of the induction coil according to the embodiment of the present invention.
FIG. 7 is a schematic perspective view showing a process of assembling the induction coil according to the embodiment of the present invention.
FIG. 8 is a schematic explanatory view showing wiring of a coil unit of the induction coil according to the embodiment of the present invention.
FIG. 9 is a schematic sectional view showing a bobbin according to the embodiment of the present invention.
FIG. 10 is a side view showing the front side of the bobbin according to the embodiment of the present invention.
FIG. 11 is a side view showing a back side surface of the bobbin according to the embodiment of the present invention.
FIG. 12 is a side view showing the outer peripheral surface of the bobbin according to the embodiment of the present invention.
FIG. 13 is a block diagram illustrating a control system of the composite electronic copying machine according to the embodiment of the present invention.
FIG. 14 is a wiring diagram showing an electric circuit of the induction coil according to the embodiment of the present invention.
FIG. 15 is a graph showing a relationship between output power of the series resonance circuit and a frequency for exciting the series resonance circuit according to the embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Main body, 20 ... Photoreceptor drum, 100 ... Fixing device, 101 ... Heating roller, 102 ... Pressure roller, 111 ... Induction coil, 111a, 111b ... 1st and 2nd induction coil, 114 ... Holder, 116 ... Winding: 117: bobbin, 118: coil, 119: coil unit, 120: high frequency generation circuit, 137: coil guide, 140: controller, 141: oscillation circuit

Claims (12)

A hollow heat-generating member that comes into contact with the recording medium and generates heat by the generation of an eddy current;
A coil support member provided in the hollow interior of the heat generating member and having a coil guide on an outer peripheral surface, and a coil formed by winding a predetermined number of turns around the outer peripheral surface of the coil support member along the coil guide; A coil unit for generating the eddy current in the heating member;
A fixing member that contacts the heating member and presses and conveys the recording medium with the heating member at a predetermined pressure. 2. The fixing device according to claim 1, wherein the coil guide is a helical groove formed in a concave shape in which the winding fits on the outer peripheral surface of the coil support member. 3. A heating roller which comes into contact with the recording medium and generates heat by the generation of eddy current;
A bobbin provided inside the heating roller and having a coil guide on an outer peripheral surface, and a coil formed by winding a winding around the outer peripheral surface of the bobbin a predetermined number of times along the coil guide, the eddy current is applied to the heating roller. A coil unit to be generated,
A fixing device, comprising: a pressure roller that contacts the heating roller and nips and conveys the recording medium with the heating roller at a predetermined pressure. The fixing device according to claim 3, wherein the coil guide is a helical groove formed in a concave shape in which the winding wire fits on an outer peripheral surface of the bobbin. A hollow heat-generating member that comes into contact with the recording medium and generates heat by the generation of an eddy current;
A coil unit provided in the hollow interior of the heat generating member and having a coil guide on an outer peripheral surface, and a coil formed by winding a predetermined number of turns around the outer peripheral surface of the coil support member along the coil guide. A plurality of coil units that are adjacent to each other and generate the eddy current in the heat generating member;
A fixing member that contacts the heating member and presses and conveys the recording medium with the heating member at a predetermined pressure. The fixing device according to claim 5, wherein the coil guide is a helical groove formed in a concave shape in which the winding wire fits on the outer peripheral surface of the coil support member. A heating roller which comes into contact with the recording medium and generates heat by the generation of eddy current;
A bobbin provided inside the heating roller and having a coil guide on an outer peripheral surface, and a plurality of coil units having a coil formed by winding a winding around the outer peripheral surface of the bobbin a predetermined number of times along the coil guide are adjacent to each other. A plurality of coil unit groups for generating the eddy current in the heating roller,
A fixing device, comprising: a pressure roller that contacts the heating roller and nips and conveys the recording medium with the heating roller at a predetermined pressure. The fixing device according to claim 7, wherein the coil guide is a spiral groove formed in a concave shape in which the winding wire fits on an outer peripheral surface of the bobbin. The fixing device according to claim 5, wherein the plurality of coil units are arranged in a direction in which adjacent windings have the same potential difference. The fixing device according to claim 5, further comprising a single holder that coaxially supports the plurality of coil unit groups. The fixing device according to claim 5, wherein the plurality of coil unit groups are excited by high-frequency power having different resonance frequencies. The fixing device according to claim 5, wherein the number of windings of the winding by the coil guide of the coil unit is different for each coil unit group.

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