JP2006251026A - Heating apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heating apparatus of an electromagnetic induction heat system, which can eliminate operation failure caused by contact of a magnetic flux adjusting member with a magnetic flux generating means by preventing occurrence of distortion when inputting the drive of the magnetic flux adjusting member disposed between the magnetic flux generating means and an induction heat generating member. <P>SOLUTION: In the heating apparatus, drive transmission means G4 and G5 for transmitting drive to move the magnetic flux adjusting member to a magnetic flux adjustment position are disposed on the corresponding longitudinal ends of a moving means used to move the magnetic flux adjusting member 7 used to adjust a magnetic flux acting area for the heat generating member in the lengthwise direction of the heat generating member 1, which is perpendicular to the direction in which a material to be heated is conveyed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  In the present invention, for example, in an image forming apparatus such as an electrophotographic system or an electrostatic recording system such as a printer or a copying machine, a heat-meltable unfixed toner image formed and supported on a recording material by a transfer system or a direct system The present invention relates to a heating device of an electromagnetic induction heating method suitable for use as a fixing device for heat fixing.

  The electromagnetic induction heating type heating device uses an electromagnetic induction heating element as a heating member (heating member), and a magnetic flux (alternating magnetic flux) is applied to the electromagnetic induction heating element by means of magnetic flux (magnetic field) generating means. In the fixing device, heat is applied to the recording material on which an unfixed toner image is formed and heated, and the toner image is heated and fixed on the surface of the recording material. It is a device to do.

  Patent Document 1 describes an electromagnetic induction heating type fixing device. In this fixing device, a metal sleeve as an induction heating member and an elastic pressure roller are arranged in parallel and pressed to rotate, and a coil assembly as a magnetic flux generating means is disposed in the metal sleeve in a non-rotating manner. The metal sleeve is inductively heated by applying a high-frequency current to the coil of the assembly to generate a high-frequency magnetic field. Then, a recording material on which an unfixed toner image is formed and supported is introduced into the pressure nip portion between the metal sleeve and the elastic pressure roller, and is nipped and conveyed, and the toner image is heated and fixed on the surface of the recording material by the heat of the metal sleeve. It is.

Further, in this fixing device, a magnetic flux adjusting member (magnetic flux shielding member) is arranged between a coil assembly as a magnetic flux generating means and a metal sleeve as an induction heating member in order to solve a so-called non-sheet passing portion temperature rise phenomenon. The magnetic flux adjusting member is moved by a driving means having a wire, a rotatable pulley on which the wire is mounted, and a motor that rotationally drives the pulley to adjust the magnetic flux to the non-sheet passing portion of the metal sleeve. There is provided a means for performing.
Japanese Patent Laid-Open No. 10-74009

  In the heating apparatus of the electromagnetic induction heating type as described above, the heat exchange efficiency is improved as the gap (clearance) between the magnetic flux generating means and the induction heating member is smaller. Therefore, the magnetic flux generating means does not cause a state in which the distance between the magnetic flux adjusting member and the magnetic flux generating means becomes abnormally close due to pressure deformation of the induction heating member, self-weight deflection or thermal deformation of the magnetic flux generating means, etc. Therefore, it is desired that a necessary clearance required for this purpose is ensured and that the magnetic flux adjusting member and the magnetic flux generating means are held at a predetermined relative position as close as possible with high accuracy.

  Further, in the case of a device configuration in which the magnetic flux adjusting member is moved within the gap between the magnetic flux generating means and the induction heating member, the magnetic flux has an arbitrary distance from the inner surface of the induction heating member so as to follow the inner surface. Since the adjusting member is provided, the magnetic flux adjusting member is brought into contact with the induction heating member due to the twist of the longitudinal central portion caused by stress concentration in the longitudinal central portion due to the load resistance received when the magnetic flux adjusting member is driven and inputted. It is desirable that the necessary clearance required to prevent the malfunction of the above is secured and that the magnetic flux adjusting member and the magnetic flux generating means are both held with high precision at a predetermined relative position as close as possible. It is.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to prevent the occurrence of torsion when a magnetic flux adjusting member disposed between the magnetic flux generating means and the induction heat generating member is driven and input in the electromagnetic induction heating type heating device, thereby preventing the magnetic flux adjusting member from being generated. It is to eliminate the malfunction caused by contact with the magnetic flux generating means.

  Another object of the present invention is to hold the relative position between the magnetic flux generating means and the magnetic flux adjusting member with high accuracy.

  Further, another object of the present invention is to stabilize the induction driving member non-operation by stabilizing the movement drive of the appropriate magnetic flux adjusting member corresponding to the size of the material to be heated without causing malfunction of the magnetic flux adjusting member. The purpose is to appropriately control the temperature rise of the paper passing section.

  In order to achieve the above object, a typical configuration of a heating device according to the present invention is a rotatable structure that heats a material to be heated by generating heat by magnetic flux generating means and magnetic flux from the magnetic flux generating means disposed inside. A magnetic flux adjusting member disposed between the heat generating member, the magnetic flux generating means and the heat generating member, and adjusting a magnetic flux acting region on the heat generating member with respect to a longitudinal direction orthogonal to the heated material conveying direction of the heat generating member; A heating device that adjusts a temperature distribution in the longitudinal direction of the heat generating member by moving the magnetic flux adjusting member to a predetermined magnetic flux adjusting position by the moving means. The moving means includes a drive transmission means for performing drive transmission for moving the magnetic flux adjustment member to the magnetic flux adjustment position, in both longitudinal directions orthogonal to the heated material conveyance direction of the magnetic flux adjustment member. Heating device, a characterized in that it comprises a part.

  According to said structure, generation | occurrence | production of the twist when a magnetic flux adjustment member is drive-inputted can be reduced, and the malfunctioning by the contact with the magnetic flux generation means of a magnetic flux adjustment member can be eliminated. In other words, the temperature of the non-sheet passing portion of the induction heating member can be appropriately increased by stabilizing the movement drive of the appropriate magnetic flux adjusting member corresponding to the size of the material to be heated without causing malfunction of the magnetic flux adjusting member. In addition to being able to control, the relative position accuracy between the magnetic flux generating means and the magnetic flux adjusting member can be improved, and the magnetic flux generating means and the magnetic flux adjusting member can be stably brought close to each other. The rise time of the heat generating member to a predetermined temperature can be shortened, and the energy consumption efficiency can be greatly improved.

(First embodiment)
(1) Example of Image Forming Apparatus FIG. 1 is a schematic model diagram of an example of an image forming apparatus in which an electromagnetic induction heating type heating apparatus according to the present invention is mounted as an image heating fixing apparatus (hereinafter referred to as a fixing apparatus). The image forming apparatus of this example is a laser printer using a transfer type electrophotographic process.

  Reference numeral 101 denotes a rotating drum type electrophotographic photosensitive member (hereinafter referred to as a photosensitive drum) as an image carrier. It is rotationally driven at a predetermined peripheral speed in the clockwise direction of the arrow.

  Reference numeral 102 denotes a contact charging roller as charging means. The outer peripheral surface of the rotating photosensitive drum 101 is uniformly charged to a predetermined polarity and potential.

  Reference numeral 103 denotes a laser scanner as exposure means. Laser light modulated in accordance with the time-series electric digital pixel signal of the image information is output, and the uniformly charged surface of the rotating photosensitive drum 101 is subjected to scanning exposure L. As a result, an electrostatic latent image corresponding to the scanning exposure pattern is formed on the photosensitive drum surface.

  Reference numeral 104 denotes a developing device. The electrostatic latent image on the surface of the photosensitive drum is reversely developed or normally developed as a toner image.

  Reference numeral 105 denotes a transfer roller as transfer means. A transfer nip T is formed by contacting the photosensitive drum 101 with a predetermined pressing force. A recording material P as a material to be heated is fed to the transfer nip T from a sheet feeding mechanism (not shown) at a predetermined control timing, and is nipped and conveyed through the transfer nip T. A predetermined transfer bias is applied to the transfer roller 105 at a predetermined control timing. As a result, the toner images on the photosensitive drum 101 surface side are sequentially electrostatically transferred onto the surface of the recording material P that is nipped and conveyed through the transfer nip T.

  The recording material P exiting the transfer nip T is separated from the surface of the photosensitive drum 101 and introduced into the fixing device 100. The fixing device 100 heats and presses and fixes the unfixed toner image on the introduced recording material P as a permanently fixed image. The recording material P is discharged and conveyed.

  A photosensitive drum cleaner 106 removes transfer residual toner on the photosensitive drum after separation of the recording material. The surface of the photosensitive drum from which the transfer residual toner has been removed and cleaned is repeatedly used for image formation.

  a is the conveyance direction of the recording material P. In the image forming apparatus according to the present exemplary embodiment, the recording material P is fed / conveyed on the basis of a central sheet passing with the center of the recording material as a conveyance reference.

(2) Fixing device 100
FIG. 2 is a front model diagram of the main part of the fixing device, and FIG. 3 is an enlarged cross-sectional model diagram. FIG. 4 is a schematic longitudinal sectional view of the fixing roller assembly portion.

  This fixing device includes a fixing roller as an induction heat generating member and a positioning member positioning unit for rotatably supporting the fixing roller for the purpose of improving the relative positional accuracy of an exciting coil assembly as a magnetic flux generating means (heating means). The fixing device is configured such that the fixing roller and the exciting coil assembly can be coaxially supported by a positioning member including positioning means for the exciting coil assembly.

  Reference numeral 1 denotes a fixing roller as an induction heating member. It is a cylindrical roller formed of an induction heating element (conductive magnetic material) such as iron, nickel, and SUS430 and having a thickness of, for example, about 0.1 mm to 1.5 mm. In general, a release layer such as a fluororesin or an elastic layer and a release layer is formed on the outer peripheral surface. By using a ferromagnetic metal such as iron (a metal with high permeability), the magnetic flux generated from the magnetic flux generating means can be more restrained inside the metal. That is, since the magnetic flux density can be increased, an eddy current can be efficiently generated on the metal surface.

  The fixing roller 1 includes a first support member 26a and a rear support member of a front support member (centering plate) 26 having front and rear end portions attached to the outside of the front plate 21 and the rear plate 22, respectively. Between the first support member 27a of the (centering plate) 27, bearings are rotatably supported via heat insulating bushes 23a and 23b and bearings 24a and 24b, respectively.

  The heat insulating bushes 23a and 23b are used to reduce heat transfer from the fixing roller 1 to the bearings 24a and 24b. G1 is a fixing roller driving gear that is externally fitted and fixed to the front end portion of the fixing roller 1. When the rotational force of the first motor M1 is transmitted to the gear G1 via a power transmission system (not shown), the fixing roller 1 is rotationally driven at a predetermined speed in the clockwise direction of the arrow in FIG. FIG. 7 is an external perspective view of the fixing roller 1 with the heat insulating bushes 23a and 23b and the fixing roller gear G1 attached thereto.

  Reference numeral 2 denotes a pressure roller as a pressure member. It is an elastic roller comprising a cored bar 2a and an elastic layer 2b formed concentrically and integrally around the cored bar 2a. The elastic layer 2b is, for example, a silicone rubber layer that is a surface-releasing heat-resistant rubber layer. The pressure roller 2 is arranged in parallel to the lower side of the fixing roller 1, and the front end and the rear end of the cored bar 2a are respectively connected between the front fixing plate 21 and the fixing rear plate 22 with bearings 25a. The bearing is supported rotatably through 25b. The bearings 25a and 25b are arranged on the front fixing plate 21 and the fixing rear plate 22 so as to be slidable in the direction of the fixing roller 1, respectively. By urging the bearings 25a and 25b in the direction of the fixing roller by urging means (not shown), the pressure roller 2 is pressed against the lower surface of the fixing roller 1 by a predetermined pressure against the elasticity of the elastic layer 2b. A fixing nip portion N having a predetermined width as a heating nip portion is formed between the fixing roller 1 and the pressure roller 2 by pressure contact with the pressure F. The pressure roller 2 is driven and rotated by receiving a frictional rotational force at the fixing nip portion N when the fixing roller 1 is rotationally driven.

  Reference numeral 3 denotes an exciting coil assembly as a magnetic flux generating means. The exciting coil assembly 3 is inserted and disposed in the inner space of the cylindrical fixing roller 1 described above. The exciting coil assembly 3 includes an exciting coil (hereinafter abbreviated as a coil) 4, a magnetic core (hereinafter abbreviated as a core) 5a and 5b arranged in a T-shaped cross section, and the coil 4 and the core 5a. An assembly of a holder 6 in which 5b is incorporated and held, and a magnetic flux adjusting member (magnetic flux shielding member, shutter) 7 that is rotatably arranged coaxially with the holder 6 on the outside of the holder 6. FIG. 8 is an external perspective view of the exciting coil assembly 3, the magnetic flux adjusting member moving means G2, G3, 28, G4, G5 and the power generating means M2. FIG. 9 is an exploded perspective view of the first and second drive transmission members G2 and G3 and the magnetic flux adjusting member 7 of the magnetic flux adjusting member moving means. FIG. 10 is an exploded perspective view of the inside of the holder 6.

  Here, in the following, regarding the constituent members and portions of the fixing device, the longitudinal direction is a direction orthogonal (crossing) to the recording material conveyance direction a on the recording material conveyance path surface.

  The holder 6 has a substantially cylindrical cross section in the entire longitudinal direction. As the material, a material obtained by adding glass to a PPS resin having both heat resistance and mechanical strength is used. For the holder 6, materials such as PPS resin, PEEK resin, polyimide resin, polyamide resin, polyamideimide resin, ceramic, liquid crystal polymer, and fluorine resin are suitable.

  As shown in FIG. 10, the holder 6 is molded in the form of a first half 6a and a second half 6b that are divided into two vertically along the longitudinal axis. The first half body 6a and the second half body 6b are overlapped and joined together with an adhesive, or joined together at a fitting structure, so that the cross-sectional shape is a substantially cylindrical member in the entire longitudinal direction. . The coil 4 and the cores 5a and 5b are incorporated into the first half 6a. The holder 6 holding the coil 4 and the cores 5a and 5b incorporated therein is assembled by superimposing and integrally joining the second half 6b so as to cover the first half 6a. Reference numerals 4a and 4b denote lead wires (lead wires) of the coil 4. The lead wires 4 a and 4 b are led out of the holder 6 through a hole 6 c provided in the front end surface of the holder 6.

  As shown in FIG. 10, the coil 4 has a substantially oval shape (horizontal boat shape) that is long in the longitudinal direction of the fixing roller 1, and is disposed inside the first half 6 a of the holder 6 along the inner surface of the fixing roller 1. Has been placed. The coil 4 generates an alternating magnetic flux sufficient for heating. For this purpose, it is necessary to make the resistance component low and the inductance component high. As the core wire of the coil 4, a litz wire in which about 80 to 160 fine wires having a diameter of 0.1 to 0.3 are bundled is used. Insulated coated wires are used for the thin wires. In addition, a coil 1 that is wound 6 to 12 times around the first core 5a is used.

  The core 5 a is a first core (vertical portion) in the winding center portion of the coil 4. The core 5b is a second core (horizontal portion) at the top thereof. These two cores 5a and 5b constitute a T-shaped core in cross section. The cores 5a and 5b are preferably made of ferrite or the like having a low high magnetic permeability residual magnetic flux density, but are not particularly limited as long as they can generate magnetic flux. Further, the shape and material of the cores 5a and 5b are not defined, and the first core 5a and the second core 5b may be integrally formed into a T-shape.

  As shown in FIG. 8, the magnetic flux adjusting member 7 basically forms a cross-sectional arc shape in the entire longitudinal direction, and arc-shaped shutter portions 7 a and 7 a having a wide width W1 in the circumferential direction on both longitudinal sides, An arc-shaped connecting plate portion 7b having a narrow width W2 between the two 7a and 7a is provided. In general, non-ferrous metals such as aluminum and copper-based metals are used as the material, and among them, materials having low electrical resistivity are preferably used. The magnetic flux adjusting member 7 is formed with bending portions 7d and 7d as engaging portions at outer diameter portions of arc portions 7c and 7c provided at both ends in the longitudinal direction. Engaging recesses G2a and G3a provided in the inner diameter portions of the first and second shutter gears G2 and G3 as first and second drive transmission means that are rotatably fitted on the rear end portion and the rear end portion, respectively. (See FIGS. 9A and 9B). In other words, the first and second shutter gears G2 and G3 are engaged with the arc portions 7c and 7c of the magnetic flux adjusting member 7, and are engaged with the bending portions 7d and 7d formed in the arc portions. As a result, the magnetic flux adjusting member 7 is supported by both ends between the first and second shutter gears G2 and G3.

  As shown in FIGS. 2 and 4, the holder 6 of the exciting coil assembly 3 has its front end protruding outward from the front end opening of the fixing roller 1, and the cylindrical end of the holder 6 of the fixing front plate 21. The front support member 26 attached to the outside is supported by being fitted into a fitting round hole 26c provided in the second support member 26b. Further, the rear end is protruded outward from the rear end opening of the fixing roller 1, and the D-shaped portion 6 d provided at the rear end is attached to the outside of the fixing rear plate 22. The member 27 is fixedly supported in a non-rotatable manner by being D-fitted in a fitting D-hole 27c provided in the second support member 27b. As a result, the holder 6 is placed in the fixing roller 1 so that the holder 6 and the fixing roller 1 are substantially coaxial, and a predetermined gap is maintained between the outer surface of the holder and the inner surface of the fixing roller, and in the circumferential direction. It is positioned and positioned non-rotating in an angular orientation. The coil lead wires 4 a and 4 b that are extended to the outside of the holder from a hole 6 c provided on the front end surface of the holder 6 are connected to the excitation circuit 51. In this embodiment, the holder 6 is positioned in the circumferential direction by D fitting, but is not limited to D fitting. If the position of the holder 6 in the circumferential direction is determined, any means can be configured.

  As described above, the magnetic flux adjusting member 7 has the bending ends 7d and 7d (FIGS. 8 and 9) provided in the arc portions 7c and 7c at both ends of the longitudinal portion at the front end portion and the rear end portion of the holder 6, respectively. The first shutter gear G2 and the second shutter gear G3, which are externally fitted to freely rotate, are engaged with each other and supported between the first and second shutter gears G2 and G3. The magnetic flux adjusting member 7 is formed by rotating the first and second shutter gears G2 and G3 with the third drive transmission means 28, G4, and G5, so that the outer surface of the holder, the inner surface of the fixing roller, and the inner surface of the fixing roller 1 In the circumferential gap of the holder 6 is pivotally moved coaxially with the holder 6.

  In the third drive transmission means 28, G4, and G5 in FIG. 8, 28 is a shaft, G4 is a first output gear, and G5 is a second output gear. The shaft 28 is arranged outside the fixing roller 1 in parallel with the fixing roller 1 and is rotatably supported between the front plate 21 and the rear plate 22 via a bearing member (not shown). The first output gear G4 and the second output gear G5 are coaxially fixed to the shaft 28, respectively, and the first output gear G4 is supplied to the first shutter gear G2 of the exciting coil assembly 3 and the second output gear. The gear G5 is meshed with the second shutter gear G3. The first output gear G4 is meshed with the output gear MG of the second motor M2, which is a power generation means. Stepping is used as the second motor M2. As the second motor M2 is rotationally driven, a rotational force is transmitted to the first and second shutter gears G2 and G3. As a result, the magnetic flux adjusting member 7 rotates around the holder 6 so as to be substantially coaxial with the holder 6. As the material of the gear, various resin materials can be selected depending on the ambient temperature and torque. The output gear MG of the second motor M2 may mesh with the second output gear G4.

  In FIG. 2, reference numeral 50 denotes a control circuit unit (CPU). The control circuit unit 50 activates the first motor M1 via the driver 52 at a predetermined control timing of the image forming sequence control. As a result, a rotational force is applied to the fixing roller driving gear G1, and the fixing roller 1 is rotationally driven in the clockwise direction indicated by the arrow in FIG. The pressure roller 2 is driven to rotate.

  Further, the control circuit unit 50 activates the excitation circuit 51 to supply an alternating current to the coil 4 at a predetermined control timing. Due to the action of the alternating magnetic flux (alternating magnetic field) generated by this, the fixing roller 1 heats up due to induction heat generation.

  FIG. 6 shows a heat generation state of the fixing roller 1 in the system as described above in a cross-sectional side view of the fixing roller 1. The main magnetic flux generation region of the magnetic flux generating means and the circumference of the fixing roller portion corresponding thereto. It is explanatory drawing of directional calorific value distribution. The coil 4 generates an alternating magnetic flux when an alternating current flows. The fixing roller 1 uses magnetic metal or magnetic material as described above, and an induced current (eddy current) is generated within the thickness of the fixing roller 1 so as to cancel the magnetic field. The fixing roller 1 itself generates heat due to the Joule heat generated by the induced current, and the temperature rises.

  In the configuration of this embodiment, the outer surface side of the first half 6a incorporating the coil 4 and the cores 5a and 5b of the holder 6 is a main magnetic flux generation region, and the magnetic flux acts on the fixing roller 1 in this magnetic flux generation region. Then, the fixing roller 1 is heated. Then, in the circumferential direction of the fixing roller 1, the distribution of heat generation amount generated by the fixing roller portion corresponding to the main magnetic flux generation region, as shown in the schematic diagram, there are portions H and H where the heat generation amount is large at two locations. To do. In the present embodiment, the holder 6 is positioned so that the one portion H is positioned corresponding to the fixing nip portion N and the other one portion H is positioned upstream of the fixing nip portion N in the rotation direction of the fixing roller. Is positioned so as to be fixedly supported in a non-rotating manner by positioning its circumferential angular posture.

  The magnetic flux adjusting member 7 is normally a gap portion corresponding to the main magnetic flux generation region as shown in FIGS. 3 and 6 in the circumferential gap between the outer surface of the holder 6 and the inner surface of the fixing roller 1. The position is moved and held in the gap portion on the opposite side. The opposite gap portion is a portion where the magnetic flux does not substantially act on the fixing roller 1 from the magnetic flux generating means, or a portion where the amount of applied magnetic flux is small. The holding position of the magnetic flux adjusting member 7 in FIGS. 3 and 6 is defined as a first switching position.

  Then, the temperature rise temperature of the fixing roller 1 is detected and controlled by a central thermistor TH1, which is a temperature detecting means disposed in contact with or in non-contact with the fixing roller 1 at a substantially central position in the longitudinal direction of the fixing roller 1. Input to the circuit 50. The control circuit 50 controls the power supplied from the excitation circuit 51 to the coil 4 so that the fixing roller detection temperature input from the central thermistor TH1 is maintained at a predetermined target temperature (fixing temperature), thereby controlling the temperature of the fixing roller 1. Take control. When the magnetic flux adjusting member 7 is held at the first switching position in FIGS. 3 and 6, the fixing roller 1 is maintained at a predetermined target temperature in the effective heating full length region in the longitudinal direction.

  In a state where the temperature of the fixing roller 1 rises to a predetermined fixing temperature and is adjusted in temperature, the recording material P carrying the unfixed toner image t is introduced into the fixing nip portion N, and is nipped and conveyed through the fixing nip portion N. Go. As a result, the unfixed toner image t is heated and pressure-fixed on the surface of the recording material P by the heat of the fixing roller 1 and the pressing force of the fixing nip N.

  Here, the paper width is a recording material dimension in a direction orthogonal to the recording material conveyance direction a on the plane of the recording material P. As described above, in the present embodiment, the recording material passing is a central paper passing reference centered on the recording material. 2 and 4, O is the recording material center paper passing reference line (virtual line). A is a sheet passing area width of a recording material having a maximum sheet width that can be used for the apparatus. A recording material having a paper width corresponding to the paper passing area width A is a large size recording material. B is a paper passing area width of a recording material having a paper width smaller than the paper width of the large size recording material. A recording material having a paper width smaller than that of the large size recording material is defined as a small size recording material. C is the difference area width between the large size recording material sheet passing area width A and the small size recording material sheet passing area width B. That is, the non-sheet passing area width generated in the recording material conveyance path when the small size recording material is passed. Since the recording material passing is based on the central reference, the non-sheet passing region when the small size recording material is passed occurs on both the left and right sides of the small size recording material passing region width B. The non-sheet passing area width C varies depending on the size of the sheet width of the small size recording material that has been passed.

  The central thermistor TH1 is used for controlling the temperature of the fixing roller 1 and corresponds to a small size recording material passing area width B which becomes a recording material passing area even if a recording material having a large or small paper width is passed. Are arranged.

  TH2 is an end thermistor which is a temperature detection means for monitoring the temperature rise of the non-sheet-passing portion, which is disposed in contact or non-contact with a position corresponding to the non-sheet-passing region width C. The detected temperature information of the end thermistor TH2 is also input to the control circuit unit 50.

  When the small-size recording material is continuously fed, the temperature of the non-sheet-passing area width C of the fixing roller 1 is increased. The temperature rise state is input to the control circuit unit 50 from the end thermistor TH2. When the non-sheet passing portion temperature rise temperature input from the end thermistor TH2 becomes higher than a predetermined allowable temperature, the control circuit portion 50 activates the second motor M2 via the driver 53 and causes the magnetic flux adjusting member 7 to move. The first switching position shown in FIGS. 3 and 6 is rotated to the second switching position shown in FIG.

  The second switching position of the magnetic flux adjusting member 7 is such that the wide arc-shaped shutter portions 7a and 7a on both longitudinal sides of the magnetic flux adjusting member 7 are in the circumferential direction between the outer surface of the holder 6 and the inner surface of the fixing roller 1, respectively. In the gap, it is a gap portion corresponding to the main magnetic flux generation region and a position that has entered the gap portion corresponding to the non-sheet passing region width C · C.

  As a result, the amount of magnetic flux applied from the magnetic flux generation means to the fixing roller portion corresponding to the non-sheet passing region width C / C is reduced, and the heat generation of the fixing roller portion corresponding to the non-sheet passing region width C / C is suppressed. . That is, the non-sheet passing portion temperature rise is suppressed.

  The shutter portions 7a and 7a may be configured to enter the entire gap portion corresponding to the main magnetic flux generation region and corresponding to the non-sheet passing region width C · C. It can also be configured to enter a part of. FIG. 5 shows a configuration in which it enters a substantially half region of the gap portion.

  After the magnetic flux adjusting member 7 has been pivotally moved to the second switching position, the control circuit unit 50, when the non-sheet passing area temperature input from the end thermistor TH2 becomes lower than a predetermined allowable temperature, that is, the non-sheet passing mode. When it is detected that the area temperature has decreased too much, the magnetic flux adjusting member 7 is returned to the first switching position and rotated to prevent the non-sheet passing area temperature from being excessively decreased.

  Further, after the magnetic flux adjusting member 7 is pivoted to the second switching position, the control circuit unit 50 moves the magnetic flux adjusting member 7 to the first when the recording material to be used for paper passing is switched from the small size recording material to the large size recording material. Return to 1 switching position and rotate.

  As described above, the first shutter gear G2 and the second shutter gear G3 are rotatably arranged at the front end portion and the rear end portion of the holder 6 as drive transmission means for driving the magnetic flux adjusting member 7, respectively. . The arcuate portions 7c and 7c at both ends of the magnetic flux adjusting member 7 form bending over 7d and 7d, which are engaged with the first shutter gear G2 and the second shutter gear G3, respectively, so that the magnetic flux adjusting member 7 is connected to the first and second shutter gears G2 and G3. The second shutter gears G2 and G3 are supported by both ends. The first shutter gear G2 and the second shutter gear G3 are fitted to the holder 6 in a region where the first and second shutter gears G2 and G3 are not engaged with the bending overs 7d and 7d of the magnetic flux adjusting member 7. For this reason, the magnetic flux adjusting member 7 is supported and rotated by the entire surface of the holder 6 and the inner diameter portions of the gears G2 and G3. In the region where the gears G2 and G3 and the holder 6 are fitted, the maximum outer diameter portion of the holder 6 forms a straight shape. Here, the maximum outer diameter portion means that the holder 6 may be thinned or the like in the fitting region. As a result, the relative position accuracy can be improved by fitting the holder 6 and the magnetic flux adjusting member 7 so that the center of the cross section is accurately aligned.

  The magnetic flux adjusting member 7 basically forms an arc shape in the entire lengthwise direction of the fixing roller, and the length of the arc portion changes from both ends to the center. When a small size recording material is fed, the temperature rise at the end of the fixing roller is suppressed by moving the shutter portions 7a and 7a at both ends of the magnetic flux adjusting member corresponding to the non-sheet passing region to the magnetic flux generating region. In addition, by moving the magnetic flux shielding member (shutter portion) to the central portion corresponding to the paper passing portion of the magnetic flux generation region, the heat generation distribution of the paper passing portion and the non-paper passing portion in the longitudinal direction of the fixing roller is changed, thereby fixing the end of the fixing roller. The temperature rise of the part may be suppressed (reverse shutter).

  Both the first and second shutter gears G2 and G3 have the same number of teeth, pitch, and diameter. The first and second output gears G4 and G5 have the same number of teeth, pitch, and diameter.

  Here, in the fixing device of the present embodiment, the relationship between the allowable torsional stress τB of the shaft 28 of the third drive transmission means and the allowable torsional stress τA of the magnetic flux adjusting member 7 is τA ≦ τB. By doing so, the magnetic flux adjusting member 7 can be smoothly rotated even if the strength of the magnetic flux adjusting member 7 is reduced or the holder 6 is slightly heated.

  According to the fixing device shown in the present embodiment, the first and second shutter gears G2 and G3 provided at both ends in the longitudinal direction of the magnetic flux adjusting member 7 even when subjected to load resistance when the magnetic flux adjusting member 7 is driven and input. Therefore, the magnetic flux adjusting member 7 is not twisted from the center, and the operation of the magnetic flux adjusting member 7 is smooth.

  Further, the engagement between the magnetic flux adjusting member 7 and the first and second shutter gears G2 and G3 provided at both longitudinal ends of the magnetic flux adjusting member is the outer diameter of the arc portions 7c and 7c at both longitudinal ends of the magnetic flux adjusting member 7. Therefore, it is possible to avoid local wear by avoiding sliding with the holder 6 at the plate thickness portion at the end of the magnetic flux adjusting member.

  In addition to this, since the arcuate portions 7c and 7c at both ends in the longitudinal direction of the magnetic flux adjusting member 7 are configured to be bent over 7d and 7d, it is not necessary to bend the end portions of the magnetic flux adjusting member extremely. Mass production processability has been remarkably improved, and it has become possible to provide the magnetic flux adjusting member 7 with high accuracy and low cost.

  Due to these effects, it is possible to give an appropriate rotational drive of the magnetic flux adjusting member 7 corresponding to the paper size without causing malfunction of the magnetic flux adjusting member 7. While achieving such performance improvement, it has also had a great effect on the improvement of life. Therefore, by stabilizing the rotational movement of the magnetic flux adjusting member 7 in accordance with the avoidance of the malfunction, it is possible to appropriately control the temperature increase of the non-sheet passing portion of the fixing roller 1.

(Second embodiment)
In the first embodiment, the fixing device in which the shaft 28 provided with the output gears G4 and G5 at both ends as the third drive transmission means is disposed in parallel with the fixing roller 1 as the induction heating member has been described. In the example, a fixing device that does not use a shaft will be described.

  FIG. 11 shows an external perspective view of an example of the exciting coil assembly 3 and the power generation means M2 in the fixing device of this embodiment.

  In the fixing device of this embodiment, two second motors (stepping motors) M2 as power generation means for driving the magnetic flux adjusting member 7 are used for the front side driving and the rear side driving of the magnetic flux adjusting member 7. The output gear MG of each second motor M2 is meshed with first and second shutter gears G2 and G3 provided at both ends in the longitudinal direction of the magnetic flux adjusting member 7. The power obtained from each of the second motors M2 and M2 is transmitted to the magnetic flux adjusting member 7 from before and after the magnetic flux adjusting member via the output gear MG and MG and the first and second shutter gears G2 and G3. .

  Although not shown, each of the first and second shutter gears G2 and G3 and the corresponding gears G4 and G5 of the third drive transmission means are provided as in the first embodiment. A gear may be provided as the drive transmission means, and a drive transmission group by the corresponding gear group may be formed to have a predetermined rotation speed.

  Therefore, the same operation and effect as in the first embodiment can be obtained in the fixing device of the present embodiment.

(Third embodiment)
FIG. 12 shows an external perspective view of an example of the exciting coil assembly 3 and the power generation means M2 in the fixing device of this embodiment.

  In the fixing device of this embodiment, a second motor (stepping motor) M2 as power generation means for driving the magnetic flux adjusting member 7 is connected to a shaft 28 as third drive transmission means. The power obtained from the second motor M2 is transmitted to the magnetic flux adjusting member 7 via the output gears G4 and M5 at both ends of the shaft 28 and the first and second shutter gears G2 and G3.

  Therefore, the same operation and effect as in the first embodiment can be obtained in the fixing device of the present embodiment.

(3) Others 1) The apparatus according to the embodiment switches the movement of the magnetic flux adjusting member 7 between the first switching position and the second switching position in accordance with two types of recording materials, a large size recording material and a small size recording material. However, it is of course possible to adopt a configuration in which the position is switched in multiple stages corresponding to three or more types of recording material paper widths. FIG. 13 is a schematic perspective view of the magnetic flux adjusting member 7 corresponding to three types of recording material paper widths of large, medium and small.

  2) Although the apparatus of the embodiment has an apparatus configuration in which the recording material is conveyed on the basis of the central sheet passing, the present invention can be effectively applied to an apparatus configuration based on the one-side sheet passing. FIG. 14 and FIG. 15 each show an example of a magnetic flux adjusting member in the case of a one-side paper passing reference device. O ′ is a one-side paper passing reference line.

  3) The electromagnetic induction heating type image heating apparatus according to the present invention is not limited to the image heating and fixing apparatus of the embodiment, but is a hypothetical fixing apparatus that presupposes an unfixed image on a recording material, and reheats a recording material carrying a fixed image. Therefore, it is also effective as an image heating apparatus such as a surface modification apparatus for modifying the image surface properties such as gloss. In addition, heating that heats the sheet-like material to be heated, such as a heat press device for removing wrinkles from the sheet-like material to be heated, a heat laminating device, a heat-drying device that evaporates the moisture content of the material to be heated, such as paper, etc. Of course, it is effective even when used as an apparatus.

Schematic model diagram of an example of an image forming apparatus Front model diagram of the main part of the fixing device Expanded cross-sectional model view of the main part of the fixing device Longitudinal cross section model of the fuser roller assembly Enlarged cross-sectional model view of the main part of the fixing device when the magnetic flux adjusting member is pivotally moved to the second switching position. Illustration of the heat generation distribution in the circumferential direction of the main magnetic flux generation area and the fixing roller part corresponding to it External perspective view of fixing roller with heat insulation bush and fixing roller gear attached External perspective view of exciting coil assembly and magnetic flux adjusting member moving means An exploded perspective view of the first and second drive transmission members and the magnetic flux adjusting member 7 Disassembled perspective view of the inside of the holder An external perspective view of an exciting coil assembly and a magnetic flux adjusting member moving means, showing an example of another fixing device An external perspective view of an exciting coil assembly and a magnetic flux adjusting member moving means, showing an example of another fixing device Perspective model view of magnetic flux adjusting member corresponding to three types of recording material paper width: large, medium and small The perspective model figure of the magnetic flux adjustment member form example in the case of the apparatus of the one-side paper passing reference | standard Perspective model view of another magnetic flux adjusting member configuration example in the case of a one-side paper passing reference device

Explanation of symbols

  1..Induction heating member (fixing roller) 2..Pressure member (pressure roller) 3..Magnetic flux generating means (excitation coil assembly) 6..Holder 7..Flux adjusting member P .. Heated material (recording material), N ... fixing nip, G2, G3 ... shutter gear, 28 ... shaft, G4 ... G5 ... output gear, M2 ... second motor

Claims (6)

A magnetic flux generating means, a rotatable heat generating member that generates heat by the magnetic flux from the magnetic flux generating means disposed inside and heats the material to be heated, and is disposed between the magnetic flux generating means and the heat generating member, A magnetic flux adjusting member that adjusts a magnetic flux acting region on the heat generating member with respect to a longitudinal direction orthogonal to the heated material conveying direction of the heat generating member, and a moving means that moves the magnetic flux adjusting member, In the heating device that adjusts the temperature distribution in the longitudinal direction of the heat generating member by moving the magnetic flux adjusting member to a predetermined magnetic flux adjusting position,
The moving means has drive transmission means for performing drive transmission for moving the magnetic flux adjusting member to the magnetic flux adjusting position at both longitudinal ends of the magnetic flux adjusting member perpendicular to the heated material conveying direction. apparatus.   The heating device according to claim 1, wherein the drive transmission means is engaged with an outer diameter portion of the magnetic flux adjusting member and is engaged with an engagement portion provided in the outer diameter portion. .   The moving means further includes third drive transmission means for performing drive transmission by synchronizing both the first and second drive transmission means provided at both ends in the longitudinal direction of the magnetic flux adjusting member. The heating apparatus according to claim 1, wherein the heating apparatus is characterized.   The heating apparatus according to claim 3, wherein a power generation means for driving the magnetic flux adjusting member is connected to the third drive transmission means.   When the allowable torsional stress in the moving direction of the magnetic flux adjusting member is τA, and the allowable torsional stress in the moving direction when performing the drive transmission of the third drive transmission means is τB, there is a relationship of τA ≦ τB. The heating apparatus according to claim 3 or 4, wherein the heating apparatus is characterized. The power generation means for driving the magnetic flux adjusting member is coupled to each of the first and second drive transmission means provided at both longitudinal ends of the magnetic flux adjusting member. 2. The heating device according to 2.

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