JP4110017B2 - Image heating device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention is particularly suitable for use as an image heating and fixing apparatus for heating and pressure-fixing an unfixed image in an image information recording apparatus (image forming apparatus) such as a copying machine, a printer, and a facsimile machine. ) Induction heating methodImage heating deviceConcerningThe
[0002]
[Prior art]
  An image heating and fixing apparatus mounted on an image forming apparatus such as an electrophotographic copying machine, printer, or facsimile will be described as an example.
[0003]
  The image heating and fixing device in the image forming apparatus is an electrophotographic, electrostatic recording,MagneticUndecided, formed by the direct method or the indirect (transfer) method on the surface of the recording material as the material to be heated, using toner (developer) made of heat-meltable resin, etc., by appropriate image forming process means such as recording Wear toner image on recording materialHardThis is a device for heat fixing processing as a received image.
[0004]
  Conventionally, as such an image heating and fixing apparatus, there are various apparatuses such as a heat source built-in roller system and an induction heating system.
[0005]
  The roller system with a built-in heat source is composed of a rotating roller pair of a fixing roller (heat roller) and a pressure roller that is heated and adjusted to a predetermined fixing temperature by incorporating a heat source such as a halogen lamp, and a pressure nip portion of the roller pair. This is a device that heats and fixes an unfixed toner image on the surface of a recording material by introducing a recording material on which an unfixed toner image is formed and supported as a material to be heated into a (fixing nip portion) and carrying it by nipping and conveying.
[0006]
  However, this apparatus has problems such as a large heat capacity of the fixing roller, a large amount of electric power required for heating, and a long wait time (waiting time from when the apparatus is turned on until a print output is enabled). Further, since the heat capacity of the fixing roller is large, there is a problem that a large amount of power is required to raise the temperature of the fixing nip portion with limited power.
[0007]
  As a countermeasure, the thickness of the fixing roller is reduced to reduce the heat capacity of the fixing roller. However, in the thin fixing roller with a reduced heat capacity, the heat flow in the longitudinal direction (the longitudinal direction of the fixing nip portion) is hindered. There has been a problem that the life of the fixing roller and the pressure roller is shortened.
[0008]
  As one of countermeasures, a fixing device using a heat source such as a halogen lamp has a configuration in which a plurality of halogen lamps having different light emission position distributions in the fixing roller longitudinal direction are used. The light emission timings of the plurality of halogen lamps are set for each paper size, and the halogen lamps are controlled to emit light at the timings, thereby taking measures against temperature rise in the non-sheet passing portion. However, in this method, since control is performed by turning on / off the halogen lamp, measures against high-frequency flicker are necessary for handling. As one of the proposals for countermeasures against high-frequency flicker, the induction heating method described below has attracted attention in recent years.
[0009]
  In the induction heating method, an induction heating element is used as a heating element, and a magnetic field is applied to the induction heating element by means of magnetic field generating means, and heat is applied to the recording material as a heated material by Joule heating based on eddy current generated in the induction heating element. This is a device that heats and fixes the applied unfixed toner image on the surface of the recording material.
[0010]
  Conventionally, for example, Patent Document 1 discloses a heat roller type apparatus that induction-heats a fixing roller made of a ferromagnetic material. The heat generation position can be close to the fixing nip portion, and a halogen lamp is used as a heat source. It achieves a more efficient fixing process than the conventional heat source roller type device.
[0011]
  However, since the heat capacity of the fixing roller is large, there is a problem that a large amount of electric power is required to raise the temperature of the fixing nip portion with limited electric power. One solution to this problem is to reduce the heat capacity of the fixing roller. For example, reducing the thickness of the fixing roller.
[0012]
  For example, Patent Document 2 discloses an induction heating type fixing device using a film-like fixing roller (film) with a reduced heat capacity.
[0013]
  However, even with a film-like fixing roller (film) with a reduced heat capacity, similarly to the heat roller, the temperature rise of the non-sheet passing portion occurs, and there is a problem that the life of the fixing film and the pressure roller is reduced.
[0014]
  Further, for example, Patent Documents 3 and 4 disclose a heating apparatus characterized by having a magnetic flux adjusting means for changing the density distribution of the acting magnetic flux with respect to the induction heating element from the magnetic flux generating means in the longitudinal direction of the fixing roller (film). Has been. One method for solving the temperature rise of the non-sheet passing portion by the induction heating type fixing device has been shown.
[0015]
  The fixing devices disclosed in Patent Documents 3 and 4 have a configuration in which a film-like induction heating element is heated. However, a temperature increase in a non-sheet-passing portion is also applied to a configuration in which a cylindrical induction heating element is used as a fixing roller. This is considered to be effective as a countermeasure against this problem.
[0016]
  As another method for solving the temperature increase in the non-sheet passing portion, there is a method in which the fixing speed is lowered when a small size recording material is passed (throughput reduction). By slowing down the fixing speed, the heat transfer time in the end direction (non-sheet passing portion) of the fixing roller is provided. However, this method reduces the productivity of the image forming apparatus.
[Patent Document 1]
            Japanese Patent Publication No. 5-9027
[Patent Document 2]
            JP-A-4-166966
[Patent Document 3]
            Japanese Patent Laid-Open No. 9-171889
[Patent Document 4]
            Japanese Patent Laid-Open No. 10-74009
[0017]
[Problems to be solved by the invention]
  As described above, known heat roller type and electromagnetic induction heating type image heating and fixing devices generally have the following problems.
[0018]
  Heat source using conventional halogen lampBuilt-inThe roller type fixing device has the following problems.
[0019]
  A supply line for supplying the electric power of the halogen lamp extends from both ends of the fixing roller. For this reason, when the fixing roller is replaced, the connection portion of the supply line must be released at the two end portions of the fixing roller. The same applies to the replacement of the halogen lamp. Therefore, when replacing the fixing roller / halogen lamp or the like, the lamp cannot be replaced by work from one side of the fixing roller.
[0020]
  When assembling, the work of passing the power supply line of the halogen lamp through the fixing roller must be performed. As a result, during assembly, for example, the supply line may come into contact with the inner surface of the fixing roller, and the supply line may be scratched or bent.
[0021]
  These problems have deteriorated serviceability such as assembly of the apparatus and replacement work of apparatus components.
[0022]
  There is a similar problem in the induction heating type fixing device based on Patent Documents 3 and 4 for preventing the temperature increase in the non-sheet passing portion.
[0023]
  In the induction heating type fixing device, a connecting portion for the supply line of the exciting coil can be provided at one end portion on one side of the fixing roller. However, nothing has been shown about the relationship between the magnetic flux adjusting means and the supply line of the exciting coil.
[0024]
  In view of this point, the present invention is an induction heating method provided with magnetic flux adjusting means for preventing temperature increase in the non-sheet passing portion.Image heating deviceImproved the assembly workability of equipment and the workability of replacing equipment components.DressIs to provide a place.
[0025]
[Means for Solving the Problems]
  According to the present inventionImage heating deviceIs characterized by the following configuration.
[0026]
  A coil unit having a coil for generating a magnetic flux and a magnetic core, a rotatable heat generating member for inductively generating heat by the generated magnetic flux and heating an image on a recording material, and shielding the magnetic flux from the coil unit toward the heat generating member. A magnetic flux shielding member for adjusting a magnetic flux distribution in a direction orthogonal to the recording material conveyance direction, a drive transmission member for transmitting a driving force to the magnetic flux shielding member, and a supply line for supplying electric power to the coil In the image heating apparatus in which the coil unit and the magnetic flux shielding member are provided inside the heat generating member,
  The drive transmission member isThe drive transmission member that has a hole portion and is rotatable is supported by the coil unit by fitting the hole portion with a shaft portion of the coil unit,The magnetic flux shielding member rotates integrally with the drive transmission member.Is possibleAnd the supply line isThe holeAn image heating apparatus characterized by being wired through.
  With the above configuration, even if an electric wire for energizing the coil is provided on the same side as the drive transmission member that transmits the drive to the magnetic flux shielding member, the wiring of the electric wire can be simplified.
[0027]
[0028]
DETAILED DESCRIPTION OF THE INVENTION
  [First Example]
  1-4 according to the present invention.Image heating deviceAs an example, an electromagnetic induction heating type fixing device is shown.
[0029]
  FIG. 1 is a cross-sectional view showing a schematic configuration in the fixing roller longitudinal direction (fixing roller axial direction) of the fixing device of this example, FIG. 2 is a cross-sectional view showing a schematic configuration of the fixing device in the radial direction of the fixing roller, and FIG. It is a disassembled perspective view explaining the structure of a member and magnetic flux generation means.
[0030]
  The fixing device shown in this example includes a shielding gear as a rotation driving member that drives a magnetic flux shielding member and a fixing roller that is an induction heating element in order to improve serviceability and assemblability of parts replacement work of the magnetic flux adjustment heating assembly It is an example about the relationship.
[0031]
  The fixing device of this example includes a magnetic flux adjustment heating assembly 1 and a fixing roller 7 (A rotatable heat generating member for heating an image on a recording material), Mainly the pressure roller 8.
[0032]
  The magnetic flux adjusting and heating assembly 1 includes an exciting coil 5 (Coil that generates magnetic flux:(Hereinafter referred to as coil) and magnetic core 6 (Magnetic core:(Hereinafter referred to as the core), a holder for holding the coil 5 and the core 6 (Coil holder) 2 and both ends of the holder 2 are pivoted(Support shaft)As an arc-shaped magnetic flux shielding plate 3 which is a magnetic flux adjusting means and is arranged to freely rotate in the counterclockwise or clockwise direction indicated by arrows a and b.
[0033]
  The magnetic flux generating means has a configuration in which the coil 5 and the T-shaped core 6 are arranged inside the fixing roller 7. The coil 5 and the core 6 are held by the holder 2 and covered with a holder lid 19.The coil 5, the core 6, the holder 2, and the holder lid 19 are a coil unit having a coil for generating magnetic flux and a magnetic core.
[0034]
  The coil 5 has a substantially elliptical shape (horizontal boat shape) in the longitudinal direction of the fixing roller 7 and is disposed inside the holder 2 along the inner surface of the fixing roller. The core 6 includes a first core 6a (vertical portion) in the winding center portion of the coil 5 and a second core 6b (horizontal portion) disposed on the upper portion thereof to constitute a T-shaped core.
[0035]
  The coil 5 must generate 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 a core wire of the coil, a litz wire in which about 80 to 160 fine wires having a diameter of 0.1 to 0.3 mm are bundled is used. Insulated coated wires are used for the thin wires. In this example, the coil 5 is configured to be wound 8 to 12 times around the first core 6a. An excitation circuit (not shown) is connected to the coil 5, and an alternating current can be supplied to the coil 5 through the circuit.
[0036]
  The core 6 may be made of a material having high permeability and low residual magnetic flux density, such as ferrite and permalloy.But specialIt is not stipulated in. The shape and material of the core are not specified in the above. For example, the effect of the present invention can be obtained even if the first core 6a and the second core 6b are integrally formed to be T-shaped.
[0037]
  The cylindrical fixing roller 7 as the induction heating element is preferably made of a ferromagnetic metal such as iron, nickel, or cobalt. By using a ferromagnetic metal (a metal having a high magnetic permeability), the magnetic flux generated from the magnetic flux generating means 5 and 6 can be more restricted in the ferromagnetic metal. That is, the magnetic flux density can be increased. Thereby, an eddy current is efficiently generated on the surface of the ferromagnetic metal (fixing roller surface), and the surface can be heated.
[0038]
  The heat capacity is reduced by setting the thickness of the fixing roller 7 to about 0.3 to 2 mm. A toner release layer (not shown) is provided on the outer surface of the fixing roller 7. Generally, it is comprised by PTFE 10-50 micrometers or PFA 10-50 micrometers. Further, a rubber layer may be used inside the toner release layer.
[0039]
  A fixing roller gear 18 is attached to one end of the fixing roller 7, and the gear is rotated by a drive motor (not shown).
[0040]
  The pressure roller 8 has a configuration in which a toner release layer is provided on the outer periphery of an iron core bar in the same manner as the silicone rubber layer and the fixing roller 7.
[0041]
  The magnetic flux adjusting means in the fixing roller longitudinal direction in the fixing device of this example is mainly composed of the magnetic flux shielding member 3, the holder 2, the shielding gear 11, and the bush 14. Among these components, the holder 2 and the magnetic flux shielding member 3 are disposed inside the fixing roller 7.
[0042]
  In the fixing device of this example, both end support portions of the holder 2 holding the coil 5 and the core 6 are set as the rotation center of the magnetic flux shielding member 3.
[0043]
  Both ends of the holder 2 are axially shaped to rotatably support the magnetic flux shielding member 3(Shaft)It is. The holder 2 has a function of holding the coil 5 and the core 6 and a function of rotating and supporting the magnetic flux shielding member 3.
[0044]
  The support shaft 2 a of the holder 2 has a shielding gear 11 for rotating the magnetic flux shielding member 3.(Drive transmission member for transmitting drive force to the magnetic flux shielding member)In order to improve the slidability of the magnetic flux shielding member 3, the support shaft 2b on the opposite side is provided with a bush 14, and the thrust direction is regulated by the thrust retaining rings 12 and 16, respectively.
[0045]
  The holder 2 is made of a non-magnetic, electrically insulating and high heat resistant material. For example, as the material of the holder 2, a material obtained by adding glass to a PPS resin having both heat resistance and mechanical strength is used. Of course, it is non-magnetic. When the holder is made of a magnetic material, the holder generates heat due to electromagnetic induction, and the heat generation efficiency of the fixing roller decreases.
[0046]
  Suitable materials for the holder include materials such as PPS resins, PEEK resins, polyimide resins, polyamide resins, polyamideimide resins, ceramics, liquid crystal polymers, and fluorine resins.
[0047]
  The material of the bush 14 and the shielding gear 11 is the same as that of the holder. Of these, it is preferable to select a material with particularly good sliding properties. For example, there are a polyamideimide resin, a PFA resin, a PEEK resin, and the like.
[0048]
  The magnetic flux shielding member 3 is composed of a non-magnetic and highly electrically conductive member. By using a non-magnetic member, there is an effect of blocking the magnetic flux. By using a good electrical conductive member, there is an effect of suppressing heat generation by electromagnetic induction of the magnetic flux shielding member itself. In this example, an aluminum alloy is used as the material of the magnetic flux shielding member 3, but an alloy such as copper, magnesium, or silver may be used.
[0049]
  The thickness of the magnetic flux shielding member 3 may be about 0.3 to 1.0 mm. If it is too thin, the magnetic flux shielding member itself generates electromagnetic induction heat. In addition, the strength is insufficient. On the other hand, if the thickness is too thick, the heat capacity of the magnetic flux shielding member increases, and when the fixing roller is heated, the heat is taken away, leading to an increase in the wait time.
[0050]
  As shown in FIG. 3, the magnetic flux shielding member 3 is provided with notches 3c and 3d having a shape that changes in stages corresponding to the paper size of the recording material (paper) as the material to be heated. In the figure, for example, in the longitudinal direction of the magnetic flux shielding member 3, the paper size width B that is smaller than the paper size width A is accommodated inside the paper size width A (maximum paper passing size) where the non-sheet passing portion temperature rise does not occur. The cutout portion 3c is provided, and the cutout portion 3d corresponding to the paper size width C smaller than the paper size width B is provided inside the paper size width B. Shielding portions (non-sheet passing portions) 3e and 3f corresponding to the paper size width B are formed at both inner ends of the paper size width A by the notches 3c, and both inner ends of the paper size width B are formed by the notches 3d. The shielding portions (non-sheet passing portions) 3g and 3h corresponding to the paper size width C are formed.
[0051]
  Therefore, the magnetic flux shielding member 3 of this example has a shape in which the shielding portions 3e, 3f and 3g, 3h corresponding to the paper size are changed in stages.
[0052]
  On the holder support shaft 2 a side, the modified hole 3 a having a notch provided at one end of the magnetic flux shielding member 3 and the cylindrical portion 11 b of the shielding gear 11 are fitted. Shielding gear11The protrusion 11a formed on the cylindrical portion 11b and the U-shaped hole 3a 'of the magnetic flux shielding member 3 are fitted,The shielding gear 11 is attached to the end of the magnetic flux shielding member 3,When the shielding gear 11 rotates, the magnetic flux shielding member 3 rotates in synchronization with the shielding gear 11. The shield gear 11 is rotationally driven by the driving means 20. The drive unit 20 may be any drive source such as a motor, and the present invention does not depend on the configuration of the drive unit. For example, the magnetic flux shielding member 3 may be rotated by an actuator such as a solenoid as a driving means and a motion transmission mechanism such as a link mechanism that converts the operation of the actuator into a rotational motion and transmits it to the shielding gear 11. . In addition, the thirdofAs shown in the embodiment, the effect of the present invention is not changed even if the shield pulley is used instead of the shield gear 11 for the rotational drive transmission of the magnetic flux shield member 3.
[0053]
  The holder support shaft 2b side is a coil supply line that supplies power to the coil 5.(Supply wire for supplying power to the coil)It has a shape that also serves as 15 guides. By making the holder support shaft 2b into a hollow pipe shape, the coil supply wire 15 is drawn through the inside.That is, the supply line 15 is wired through the inside of the holder support shaft 2b.A holding hole 3b provided on the other end side of the magnetic flux shielding member 3 is rotatably fitted to the cylindrical portion 14a of the bush 14 on the holder support shaft 2b. A connector portion 15 a is provided at the end of the coil supply line 15 and is connected to the power control device 25. An alternating current is supplied to the coil 5 through the coil supply line 15 by controlling an excitation circuit (not shown) by the power control device 25.
[0054]
  The holder 2 is supported on the support shaft 2 a side by a holder support plate 13, and the support shaft 2 b side is supported by a holder support member 17. The shape of the fitting portion between the support shaft 2a and the holder support plate 13 is a D-shaped shape (D cut). With the D-shape, the holder 2 is positioned in the circumferential direction of the fixing roller. As a result, the holder 2 is positioned so that the shaft center 2c (see FIG. 3) of the support shaft 2a and the support shaft 2b is coaxial with the rotation shaft center 7c (see FIG. 1) of the fixing roller 7.
[0055]
  As shown in FIG. 1, the outer diameter φX of the shielding gear 11 is the inner diameter of the fixing roller 7.Diameter φIt is smaller than Y. The relational expression is as follows.
[0056]
    (Outer diameter φX of shielding gear 11) <(Inner diameter φY of fixing roller 7)
  With this configuration, the firstofIn the embodiment, the service / assembly operation described below can be performed from the direction of the supply line 15 of the coil 5 (the support shaft 2b side of the holder 2).
[0057]
  With reference to FIGS. 1 and 8, an example of the assembly procedure of the fixing device of the first embodiment will be described.
[0058]
  As shown in FIG. 8A, first, the fixing roller 7 is assembled to the fixing roller support plates 28a and 28b with the respective bearings 27a and 27b. On the bearing 27b side, the fixing roller gear 18 is provided.(Heat-generating member drive transmission member)The fixing roller thrust stopping member (not shown) regulates the thrust of the fixing roller. Up to here, it is the same as the conventional one.
[0059]
  Next, the magnetic flux adjusting and heating assembly 1 is inserted into the inside of the roller from the one end portion (end portion on the bearing 27b side) of the fixing roller 7 with the shielding gear 11 at the head. Further, the magnetic flux adjusting and heating assembly 1 is pushed out to the end of the fixing roller 7 opposite to the end (the end on the bearing 27a side), and the holder support shaft 2a is fitted into the fitting hole 13a of the holder support plate 13. Let
[0060]
  Next, the holder support member 17 is fitted and attached to the holder support shaft 2b (hollow shape portion that also serves as a guide for the coil supply line 15) shown in FIG. The coil supply line 15 is connected to the power control device 25 via the connector portion 15a. This completes the assembly of the magnetic flux adjustment heating assembly 1 to the fixing roller 7.
[0061]
  As described above, in the configuration of the fixing device shown in this example, since the assembly can be performed without the operation of passing the coil supply line 15 inside the fixing roller, scratches, bending, stress, etc. on the supply line at the time of assembly can be prevented. No longer give. Further, the assembly work can be performed entirely from one end portion of the fixing roller 7 (end portion on the fixing roller gear 18 side), and the assembly workability is improved.
[0062]
  Next, an example of a disassembling procedure for parts replacement service such as replacement of the fixing roller / magnetic flux generating means will be described.
[0063]
  In the case of parts replacement service, the members are basically removed in the reverse order of assembly. First, the connection between the coil supply line 15 and the power control device 25 shown in FIG. 1 is released at the end portion on one side of the fixing roller 7. Next, the fitting between the holder support member 17 and the holder support shaft 2b is released. Finally, as shown in FIG. 8B, the magnetic flux adjusting and heating assembly 1 is pulled from the inside of the fixing roller from the support shaft 2b side of the holder 2 and removed.
[0064]
  Thus, in this example, since all service work such as parts replacement can be performed from one end of the fixing roller, service workability can be improved. Therefore, disassembly and assembly can be performed without performing the operation of passing (or pulling out) the coil supply line into the fixing roller, so that there is no particular damage, bending, stress, or the like on the supply line during assembly.
[0065]
  As above, firstofIn the fixing device of the embodiment, the holder 2 and the magnetic flux shielding member 3 that hold the magnetic flux generation means 5 and 6 in a relationship of (the outer diameter φX of the shielding gear 11) <(the inner diameter φY of the fixing roller 7) are one assembly (unit ), The assemblability and exchangeability (serviceability) of the fixing roller and magnetic flux generating means can be improved.
[0066]
  In the fixing device of this example, the magnetic flux shielding member 3 is rotated by a predetermined angle in the predetermined direction by the driving means 20 by an angle corresponding to the paper size, and the shielding portion 3e having a shape that changes stepwise of the magnetic flux shielding member. 3f, 3g, and 3h are pivotally moved to the facing portion of the core 6a. By shielding the magnetic flux lines passing from the core 6a to the fixing roller 7 by this shielding portion, heat generation of the fixing roller is mitigated at the shielding portion, and an abnormal temperature rise is prevented.
[0067]
  In the magnetic flux shielding member 3 shown in this example, the two-stage magnetic flux adjustment of the paper size width B and the paper size width C which are smaller than the paper size width A (maximum paper passing size) where the temperature rise of the non-sheet passing portion does not occur is possible. . For example, for a metric paper size, the paper size width A is A4 width (297 mm), the paper size width B is B4 width (257 mm), and the paper size width C is A4R width (210 mm). In this case, the entire length of the notch is set to a notch width (paper size width) that changes stepwise corresponding to the respective paper size widths A, B, and C. The paper size is determined by the specifications of the image forming apparatus on which the fixing device is mounted. Further, the shielding part (or notch part) of the magnetic flux shielding member 3 is not limited to two stages, and the shielding part (stepping part) that changes step by step depending on the size at which the non-sheet passing part temperature rise occurs. Alternatively, the number of cutout portions) can be increased or decreased, and even if one or three or more are provided, a non-sheet-passing temperature rise prevention effect according to the paper size can be obtained.
[0068]
  In the fixing device of this example, as described above, the shaft center 2c (see FIG. 3) of the support shaft 2a and the support shaft 2b of the holder 2 holding the magnetic flux shielding member 3 is used as the rotation shaft center of the fixing roller 7.( Axis of rotation )7c (see FIG. 1), the magnetic flux shielding member 3 has the shielding gear 11 and the bush 14 on the holder support shafts 2a and 2b coaxial with the rotation shaft center 7c of the fixing roller 7. Via the fixing roller 7.That is, the magnetic flux shielding member 3 is rotatable, and the rotational center of the magnetic flux shielding member 3 and the rotational center of the fixing roller 7 as a heat generating member are on the same axis.As a result, it is not necessary to provide a standby space for the magnetic flux shielding member outside the fixing roller, for example, outside the end of the fixing roller, thereby saving space.
[0069]
  Further, since the magnetic flux shielding member 3 can be rotationally driven by the drive means 20 disposed on one side (the support shaft 2a side of the holder 2) at the rotation shaft center 7c of the fixing roller 7, the installation space of the drive means can be reduced. It only needs to be provided on the support shaft 2a side, and space saving in the fixing roller thrust direction is possible.
[0070]
  In the fixing device shown in this example, as shown in FIGS. 1 and 2, the fixing roller 7 and the pressure roller 8 that contain the assembly 1 are brought into pressure contact with each other up and down and assembled in a device housing (not shown). A fixing nip portion (heating nip portion) N having a predetermined width is formed between the two 7 and 8.
[0071]
  The fixing roller 7 is rotated in the clockwise direction indicated by the arrow P by the fixing roller gear 18, and the pressure roller 8 is also driven and rotated in the counterclockwise direction indicated by the arrow Q.
[0072]
  The coil 5 generates an alternating magnetic flux by an alternating current supplied from the power control device 25. The alternating magnetic flux is guided to the core 6 and acts on the fixing nip N, and an eddy current is generated on the surface of the fixing roller at the fixing nip N. Let The eddy current generates Joule heat due to the specific resistance of the roller surface. That is, by supplying an alternating current to the coil, the fixing roller 7 enters an electromagnetic induction heat generation state at the fixing nip portion N.
[0073]
  The temperature of the fixing nip N is controlled to a predetermined fixing temperature by controlling the alternating current supplied from the power control device 25 to the coil 5 by a temperature control system including a temperature detection sensor (not shown).
[0074]
  Accordingly, the fixing roller 7 is rotated by the rotation of the fixing roller gear 18, and an alternating current is supplied from the power control device 25 to the coil 6 so that the temperature of the fixing nip portion N rises to a predetermined temperature and is adjusted in temperature. A recording material (paper) S carrying a non-fixed toner image as a heated material between the fixing roller 7 and the pressure roller 8 in the fixing nip portion N follows a paper conveyance path (one-dot chain line) H along an arrow C. When the recording material is introduced from the direction, the recording material and the unfixed toner image are heated by the heat generated by the fixing roller 7 and the toner image is heated and fixed. The recording material that has passed through the fixing nip N is separated from the outer surface of the fixing roller by the separation claw 30 on the exit side of the fixing nip and conveyed.
[0075]
  Next, the operation and action of the magnetic flux shielding member in the fixing device of this example will be described with reference to FIG. 4 which is an image diagram of the magnetic circuit.
[0076]
  Magnetic field lines Ja (illustrated by a two-dot chain line) indicate a magnetic circuit of the generated magnetic field lines when electric power (alternating current) is input from the power control device to the magnetic flux generating means. The magnetic field lines Ja pass through the first core 6a (vertical portion), the fixing roller 7, and the second core 6b (horizontal portion). Actually, the lines of magnetic force pass through the inside of the fixing roller having a high magnetic permeability, but are shown as in FIG. 4 for easy understanding.
[0077]
  Here, let us consider a heat generation point due to electromagnetic induction heating in the fixing roller 7.
[0078]
  The heating point is particularly large at the fixing roller portion where the coil 5 faces. This is considered to be because the magnetic flux density is increased in the fixing roller portion opposed to the coil 5 because the first core 6a and the second core 6b are generated so that the lines of magnetic force go back and forth. Taking this into consideration, the magnetic flux generation means 5 and 6 of this example are arranged so as to be inclined so that the heating nip comes in front of the fixing nip N portion. Furthermore, the fixing roller 7 is rotated and heated without temperature unevenness.
[0079]
  The magnetic flux adjusting means is provided based on the above-described electromagnetic induction heating principle. In the magnetic flux adjusting means of this example, the magnetic flux shielding member 3 changes the path of the magnetic flux going back and forth inside the fixing roller. Thereby, the heat generation by electromagnetic induction in the longitudinal direction of the fixing roller is controlled.
[0080]
  That is, by placing the magnetic flux shielding member 3 between the core 6 and the fixing roller 7, the heat generation of the fixing roller can be efficiently reduced. In particular, in the case of the T-shaped core 6, it is efficient to shield the first core (vertical portion) 6a. As shown in FIG. 4 (a), the magnetic flux lines Ja have a higher density in the first core 6a than in the second core (horizontal portion) 6b, and are separated from the end of the first core to the end of the second core. Therefore, it is efficient to shield the magnetic flux line Ja at this magnetic circuit position.
[0081]
  As shown in FIG. 4A, the magnetic flux shielding member 3 stands by in a range where there is little influence on the magnetic circuit Ja when the paper size width A does not cause the non-sheet passing portion temperature rise. In the figure, the magnetic flux shielding member 3 stands by at a position where the magnetic circuit Ja does not exist. Since the magnetic flux shielding member 3 at this position does not affect the magnetic circuit Ja, fixing processing by electromagnetic induction heating is possible in the entire width of the paper size width A.
[0082]
  When the paper size width B where the temperature rise of the non-sheet passing portion occurs, the magnetic flux shielding member 3 rotates and moves on the magnetic circuit Ja shown in FIG. 4A as shown in FIG. Inhibit. In the figure, the shielding portions 3e and 3f of the magnetic flux shielding member 3 face the first core 6a and obstruct the flow of magnetic flux. The magnetic circuit Jb shown in the figure is a magnetic circuit when shielded by the width Ba (Bb) (see FIG. 3) of the shielding part 3e (3f). In the width Ba (Bb) of the shielding portion 3e (3f), which is a non-sheet passing portion when the paper size width is B, the magnetic flux passing through the inside of the fixing roller is smaller than that in the case of FIG. I understand. Thereby, in the range of width Ba * Bb of shielding part 3e * 3f, the heat_generation | fever by electromagnetic induction reduces and it can suppress non-sheet passing part temperature rising. At this time, the paper size width B (notch 3c)
Becomes a fixing possible region by electromagnetic induction heating.
[0083]
  The same applies to the paper size width C where the non-sheet passing portion temperature rise occurs. The magnetic flux shielding member 3 further rotates on the magnetic circuit Ja. In the figure, the shielding part 3g (3h) of the magnetic flux shielding member 3 faces the first core 6a and obstructs the flow of magnetic flux. The magnetic circuits Jc and Jc 'shown in the figure are magnetic circuits when shielded by the width Ca (Cb) (see FIG. 3) of the shielding part 3g (3h). With the added width (Ba + Ca) of the shielding portions 3e and 3g and the added width (Bb + Cb) of the shielding portions 3f and 3h, which are non-sheet passing portions when the paper size width is C, the magnetic flux passing through the fixing roller is as shown in FIG. ) And magnetic circuits Jb and Jc · Jc ′ shown in FIG. It can be seen that the magnetic flux passing through the inside of the fixing roller in the range of the width (Ba + Ca) · (Bb + Cb) is smaller than that in the case of FIG. Thereby, electromagnetic induction heat_generation | fever reduces in the range of a width | variety (Ba + Ca) and (Bb + Cb), and a non-sheet passing part temperature rising can be suppressed. At this time, the paper size width C (notch portion 3d) becomes a fixable region by electromagnetic induction heating.
  As described above, the magnetic flux shielding member 3 is a member that shields the magnetic flux from the magnetic flux generating means (coil unit) toward the fixing roller 7 that is a heat generating member and adjusts the magnetic flux distribution in the direction orthogonal to the recording material conveyance direction. .
  Further, as shown in FIG. 1, a fixing roller gear 18 that is a drive transmission member for a heat generating member for transmitting a driving force to the fixing roller 7 that is a heat generating member, and a shielding gear 11 that is disposed with respect to the magnetic flux shielding member 3. It is attached to the end of the fixing roller 7 on the side opposite to the end.
[0084]
  [Second Example]
  The fixing device of the second embodiment will be described with reference to FIG.
[0085]
  In the fixing device shown in this example, the magnetic flux generating means 5 and 6, the fixing roller 7, the pressure roller 8 and the like are the first ones.ofThe same reference numerals are used for the same functions as in the embodiment. The material of the magnetic flux shielding member 3 is also the firstofIt is the same as that of an Example.
[0086]
  In the configuration of the fixing device of the second embodiment, the relationship between the outer diameter φX of the shielding gear 11 and the inner diameter φY of the fixing roller is not particularly specified.
[0087]
  secondofIn the example, the firstofUnlike the examples,
    (Outer diameter φX of shielding gear 11)> (Inner diameter φY of fixing roller 7)
It does not matter even if it is a relationship.
[0088]
  In the second embodiment, the holder support shaft 2 a has a shape that also serves as a guide for the supply line 15 that supplies power to the coil 5. By making the holder support shaft 2a into a hollow pipe shape, the coil supply wire 15 is drawn out of the fixing roller through the inside thereof. A shielding gear 11 is rotatably provided on the outer diameter of the holder support shaft 2a. The coil supply line 15 passes through the inside of the shielding gear 11, is connected to the power control device 25 by the connector portion 15 a, and supplies power to the coil 5. That is, the shielding gear 11 that is a drive transmission member is a hole.(Hole)And a supply line 15 for supplying power to the coil 5 is wired through the hole. The rotation axis of the fixing roller 7 is inside the hole.
[0089]
  The holder 2 is supported by a holder support plate 13 on the support shaft 2a side and a holder support member 17 on the support shaft 2b side. The shape of the fitting portion between the support shaft 2b and the holder support member 17 is a D-shaped shape (D cut). With the D-shape, the holder 2 is positioned in the circumferential direction of the fixing roller.
[0090]
  secondofIn the embodiment, the shape of the tip portion 2bT of the holder support shaft 2b is a tapered shape. Thereby, at the time of an assembly, the magnetic flux adjustment heating assembly 1 can be smoothly inserted into the D-shaped fitting hole 17a of the holder support member 17. firstofIn the fixing device shown in the embodiment, it goes without saying that the same effect can be obtained even if the tip of the holder support shaft 2a on the opposite side of the coil supply line is tapered.
[0091]
  With reference to FIGS. 6 and 9, an example of the assembly procedure of the fixing device of the second embodiment will be described.
[0092]
  As shown in FIG. 9A, first, the fixing roller 7 is assembled to the fixing roller support plates 28a and 28b with the respective bearings 27a and 27b. A fixing roller gear 18 is attached to the bearing 27b side, and a fixing roller thrust stop member (not shown) regulates the thrust of the fixing roller. Up to here, it is the same as the conventional one.
[0093]
  Next, the magnetic flux adjustment heating assembly 1 is inserted into the roller from one end of the fixing roller 7 (end on the bearing 27a side) with the tapered tip end 2bT of the holder support shaft 2b as the head. Further, the magnetic flux adjusting / heating assembly 1 is pushed into the end opposite to the end of the fixing roller 7 (the end on the bearing 27b side), and the tapered tip end 2bT of the holder support shaft 2b is inserted into the holder support member 17. Is inserted into the D-shaped fitting hole 17a.
[0094]
  Next, as shown in FIG. 6, the holder support plate 13 is fitted and attached to the holder support shaft 2a (hollow shape portion that also serves as a guide for the coil supply line 15). The coil supply line 15 is connected to the power control device 25 via the connector portion 15a. This completes the assembly of the magnetic flux adjustment heating assembly 1 to the fixing roller 7.
[0095]
  As described above, in the configuration of the fixing device shown in this example, since the assembly can be performed without the operation of passing the coil supply line 15 inside the fixing roller, scratches, bending, stress, etc. on the supply line at the time of assembly can be prevented. No longer give. Further, the assembly work can be performed entirely from one end portion of the fixing roller 7 (the end portion opposite to the end portion on the fixing roller gear 18 side), and the assembly workability is improved.
[0096]
  In the second embodiment, the outer diameter φX of the shielding gear 11 is not limited in relation to the inner diameter φY of the fixing roller 7 (because the magnetic flux adjustment heating assembly 1 is inserted into the fixing roller from the holder support shaft 2b side). ), There is an advantage that the degree of freedom of design increases. Since the shielding gear 11 does not pass through the fixing roller, scratches or dents can be eliminated from the shielding gear.
[0097]
  Next, an example of a disassembling procedure for parts replacement service such as replacement of the fixing roller / magnetic flux generating means will be described.
[0098]
  In the case of parts replacement service, the members are basically removed in the reverse order of assembly. At the end portion on one side of the fixing roller 7, first, the connection portion between the coil supply line 15 and the power control device 25 shown in FIG. 6 is released. Next, the fitting between the holder support plate 13 and the holder support shaft 2a is released. Finally, as shown in FIG. 9B, the magnetic flux adjusting and heating assembly 1 is pulled from the inside of the fixing roller from the support shaft 2a side of the holder 2 and removed.
[0099]
  Thus, in this example, since all service work such as parts replacement can be performed from one end of the fixing roller 7, service workability can be improved. Therefore, disassembly and assembly can be performed without performing the operation of passing (or pulling out) the coil supply line into the fixing roller, so that there is no particular damage, bending, stress, or the like on the supply line during assembly.
[0100]
  As above, the secondofIn the fixing device of the embodiment, the coil supply line 15 of the coil 5 in the magnetic flux adjusting and heating assembly 1 passes through the inside of the shielding gear 11, and the shape of the holder tip 2bT on the opposite side of the coil supply line is a tapered shape. . Furthermore, since the holder 2 for holding the magnetic flux generating means 5 and 6 and the magnetic flux shielding member 3 are compactly constituted by one assembly (unit), the assembling and exchanging properties (serviceability) of the fixing roller and the magnetic flux generating means are made. Can be improved.
[0101]
  [Third embodiment]
  A fixing device according to a third embodiment will be described with reference to FIG.
[0102]
  In the fixing device shown in this example, the magnetic flux generating means 5 and 6, the fixing roller 7, the pressure roller 8 and the like are the first ones.ofThe same reference numerals are used for the same functions as in the embodiment. The material of the magnetic flux shielding member 3 is also the firstofIt is the same as that of an Example.
[0103]
  In the third embodiment, a shield pulley is used instead of the shield gear 11 shown in the first embodiment, and the belt 21 is spanned between the pulley 11 and the pulley 20a of the driving means 20. Further, the outer diameter φX of the shielding pulley 11 is smaller than the inner diameter φY of the fixing roller 7. The relational expression is the same as in the first embodiment and is as follows.
[0104]
    (Outer diameter φX of shielding pulley 11) <(Inner diameter φY of fixing roller 7)
  In the third embodiment, the tip 2bT of the support shaft 2b of the holder 2 has a tapered shape as in the second embodiment.
[0105]
  Further, in the third embodiment, the size in the circumferential direction of the fixing roller is larger than that in the other embodiments, and the holder support functioning as the rotation axis center 7c of the fixing roller 7 and the rotation center axis of the magnetic flux shielding member 3 is supported. The positions of the shafts 2a and 2b are different from those of the shaft center 2c. That is, in the radial cross section of the fixing roller 7, the rotation axis center 7 c of the fixing roller 7 and the axis center 2 c of the magnetic flux shielding member 3 are eccentric.
[0106]
  In the fixing device of this example, there are two kinds of disassembling procedures for assembling procedures and parts replacement services of the magnetic flux adjusting and heating assembly 1 to the fixing roller 7. One is based on the relationship of the outer diameter φX of the shielding pulley 11 <the inner diameter φY of the fixing roller 7 in the same procedure as in the first embodiment, and the other is the support shaft 2 b of the holder 2. Based on the fact that the tip 2bT is tapered, the same procedure as in the second embodiment is performed. Which of these two assembling procedures is adopted is appropriately determined according to the position of the opening / closing door of the image forming apparatus on which the fixing device is mounted.
[0107]
  Therefore, even in this example apparatus, the firstThe secondThe same effect as the apparatus of the embodiment can be obtained.
[0108]
  Further, as in this example, when the large-diameter fixing roller 7 is used, the magnetic flux adjusting and heating assembly 1 that is used with a smaller-diameter fixing roller can be used. It becomes possible and leads to cost reduction.
[0109]
  Further, as a fixing device of another embodiment, it can be easily estimated from the third embodiment that a plurality of magnetic flux adjusting and heating assemblies can be provided on one fixing roller for a fixing roller having a larger diameter.
[0110]
  As described above, according to the fixing device of each embodiment, the fixing roller 7 can be assembled without passing the coil supply line 15 through the fixing roller 7, so that the supply line is scratched or bent during assembly.・ No more stress. Further, service work such as parts replacement can be performed from one end of the fixing roller 7, so that service workability can be improved. As a result, disassembly and assembly can be performed without the operation of passing (or pulling out) the coil supply line into the fixing roller, so that the assembly workability of the apparatus and the replacement workability of the apparatus components can be improved.
[0111]
  [Example of image forming apparatus]
  The fixing device of each embodiment is mounted on, for example, an electrophotographic image forming apparatus. FIG. 5 is an explanatory diagram of a schematic configuration showing an example of an image forming apparatus provided with the fixing device 10 of the first embodiment.
[0112]
  The image forming apparatus 100 reads an image of a document with the image reading unit 108, and exposes the surface of the photosensitive drum 101 from the image writing unit 109 according to a command from a controller (not shown) based on the read image data. Thus, an electrostatic latent image is formed on the photosensitive drum 101. Prior to exposure, the surface of the photosensitive drum 101 is uniformly charged to a predetermined potential by the charger 102, and laser light is emitted from the image writing unit 109 onto the uniformly charged photosensitive drum 101. Etc., an electrostatic latent image is formed on the photosensitive drum 101. The electrostatic latent image formed on the photosensitive drum 101 is developed with the toner of the developing device 103, and then the developed toner image is conveyed to a portion facing the transfer device 104 by the rotation of the photosensitive drum 101.
[0113]
  Corresponding to the conveyance of the developed toner image, the paper S is fed from the paper cassette one by one by the pickup roller 132 and the photosensitive drum 101 and the transfer device 104 are opposed to each other at a timing by the registration roller pair 135. It is conveyed to the part. Then, when the paper S passes through the facing portion between the photosensitive drum 101 and the transfer device 104, the developed toner image on the photosensitive drum 101 is transferred onto the paper S by the transfer device 104.
[0114]
  The sheet S on which the toner image has been transferred is conveyed to the position of the fixing roller 7 by a predetermined conveying device, pressed against the fixing roller 7 and the pressure roller 8, and electromagnetically generated by magnetic flux generation means provided in the fixing roller. The toner on the sheet S is melted and fixed on the sheet S by induction heating. Thereafter, the sheet S on which the toner image is fixed is stored in the tray 115 outside the apparatus main body by the paper discharge roller 111, and a series of image forming processes is completed.
[0115]
  [Others]
  As the fixing device of this embodiment, a desired one is adopted in a timely manner according to the specifications of the image forming apparatus, and is used by being mounted on a predetermined image forming apparatus.
[0116]
  Three examples of the heating device according to the present invention have been shown. However, in the fixing devices shown in the first and second embodiments, like the fixing device of the third embodiment, the support shaft 2a. Even if the holder 2 is arranged inside the fixing roller so that the shaft center 2c of the support shaft 2b and the rotation shaft center 7c of the fixing roller 7 are different, the effect of the present invention does not change.
[0117]
  In particular, in the fixing device shown in each embodiment, the holder 2 holding the magnetic flux generating means and the magnetic flux shielding member 3 are compactly configured by one assembly (unit), so that space saving and cost reduction are achieved. Thus, it is possible to realize an induction heating type fixing device using magnetic flux adjusting means, which has improved power saving and productivity.
[0118]
  Moreover, although the example using the fixing roller as the induction heating element has been described for the fixing device of each embodiment, the effect of the present invention does not change even if a fixing film similar to the conventional example is used instead of the fixing roller.
[0119]
  The image forming method of the image forming apparatus equipped with the fixing device is not limited to the electrophotographic method, and may be an electrostatic recording method, a magnetic recording method, or the like, or may be a transfer method or a direct method.
[0120]
  Of the present inventionImage heating deviceIs not limited to the image heating and fixing device of the embodiment, but an image heating device that heats a recording material carrying an image to improve surface properties such as gloss, and an image heating device that is supposed to be worn.AndCan be used.
[0121]
  While various examples and embodiments of the present invention have been shown and described above, the spirit and scope of the present invention are not limited to the specific descriptions and figures in the present specification by those skilled in the art. It will be understood that various modifications and changes are set forth in all the claims that follow.
[0122]
[0123]
[0124]
[0125]
[0126]
[0127]
[0128]
[0129]
[0130]
[0131]
[0132]
[0133]
[0134]
[0135]
【The invention's effect】
  As described above, according to the present invention, it is possible to improve the assembly workability of the apparatus and the replacement workability of the apparatus component parts.
  Even if an electric wire for energizing the coil is provided on the same side as the drive transmission member that transmits the drive to the magnetic flux shielding member, the wiring of the electric wire can be simplified.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view of a fixing device according to a first embodiment in a longitudinal direction (fixing roller axial direction) of a fixing roller.
FIG. 2 is a schematic cross-sectional view of the fixing device according to the first embodiment in the fixing roller radial direction.
FIG. 3 is an exploded perspective view of a configuration of a magnetic flux adjustment heating assembly of the fixing device according to the first embodiment.
FIG. 4 is an image diagram of a magnetic circuit when a magnetic flux is shielded by a magnetic flux shielding member in the fixing device of the first embodiment.
FIG. 5 is a schematic configuration diagram illustrating an example of an image forming apparatus equipped with the fixing device according to the first embodiment.
FIG. 6 is a schematic sectional view of a fixing device according to a second embodiment in the longitudinal direction of the fixing roller.
FIG. 7 is a schematic sectional view of a fixing device according to a third embodiment in the longitudinal direction of the fixing roller.
FIG. 8 is an explanatory diagram showing an example of an assembly procedure / disassembly procedure of the fixing device according to the first embodiment.
FIG. 9 is an explanatory diagram illustrating an example of an assembling procedure / disassembling procedure of a fixing device according to a second embodiment.
[Explanation of symbols]
  1: magnetic flux adjusting heating assembly, 2: holder, 2a (2b): holder support shaft, 3: magnetic flux shielding member, 4: magnetic flux generating means, 5: exciting coil, 6: magnetic core, 6a: first magnetic body Core: 6b: Second magnetic core, 7: Fixing roller, 8: Pressure roller 11: Shielding gear (or shielding pulley) 15: Coil power supply line, N: Fixing nip, Ja, Jb, Jc, Jc ': Magnetic field lines (magnetic circuit) of the magnetic flux generator

Claims (7)

A coil unit having a coil for generating a magnetic flux and a magnetic core, a rotatable heat generating member for inductively generating heat by the generated magnetic flux and heating an image on a recording material, and shielding the magnetic flux from the coil unit toward the heat generating member. A magnetic flux shielding member for adjusting a magnetic flux distribution in a direction orthogonal to the recording material conveyance direction, a drive transmission member for transmitting a driving force to the magnetic flux shielding member, and a supply line for supplying electric power to the coil In the image heating apparatus in which the coil unit and the magnetic flux shielding member are provided inside the heat generating member,
The drive transmission member has a hole, and the rotatable drive transmission member is supported by the coil unit when the hole engages with a shaft of the coil unit, and the magnetic flux shielding member An image heating apparatus, wherein the image forming apparatus is rotatable integrally with a transmission member, and the supply line is wired through the hole . The rotation axis of the heat generating member is an image heating apparatus according to claim 1, characterized in that on the inside of the hole. An apparatus according centers of rotation and the heating member to claim 1 or claim 2, characterized in that on the same axis before Symbol magnetic flux shielding member.   The image heating apparatus according to claim 1, wherein an inner diameter of the heat generating member is larger than an outer diameter of the drive transmission member.   The image heating apparatus according to claim 1, wherein an inner diameter of the heat generating member is smaller than an outer diameter of the drive transmission member. End of the heating member in said heating member for the drive transmission member for transmitting the driving force to the heating member is opposite to the end portion side where the drive transmission member relative to the magnetic flux shielding member is disposed The image heating apparatus according to claim 1, wherein the image heating apparatus is attached to a portion.   The coil unit includes a coil holder that supports the coil, the coil holder is provided with a support shaft that supports the magnetic flux shielding member at both ends, the drive transmission member is supported by the support shaft, and The image heating apparatus according to claim 1, wherein the supply line is wired through the inside of the support shaft.

Images