JP2009098357A - Image forming apparatus - Google Patents

Abstract

In an induction heating fixing device, particularly in a system in which heating is performed by an excitation coil provided outside a cylindrical fixing heating sleeve, the fixing sleeve can be pressed and held and rotated and driven, and vibration and noise are generated. To prevent.
Represented by an induction heating inverter device, a fixing heating sleeve 101 having an induction heating heating element, a pressure mechanism that pressurizes and holds the fixing heating sleeve 101 on a fixing pressure roller 108, a fixing pressure roller 108, and a thermistor. The temperature detecting element and the safety element such as the thermo switch 106 are used. A sleeve guide provided inside the fixing heating sleeve 101 and disposed opposite to the exciting coil 105 may be disposed.
[Selection] Figure 1

Description

  The present invention relates to a belt heating type heating apparatus and an image forming apparatus such as an electrophotographic apparatus and an electrostatic recording apparatus provided with the heating apparatus as an image heating apparatus.

  For convenience, an image heating apparatus (fixing apparatus) that is provided in an image forming apparatus such as a copying machine or a printer and that heats and fixes a toner image onto a recording material will be described as an example.

  In an image forming apparatus, a recording material (transfer material sheet, electrofax sheet, electrostatic recording paper, OHP sheet, printing paper, printing paper, electrophotographic process, electrostatic recording process, magnetic recording process, etc. As a fixing device that heats and fixes an unfixed image (toner image) of target image information formed and supported on a recording sheet or the like by a transfer method or a direct method as a permanently fixed image on a recording material surface, a heat roller device Was widely used. Recently, belt heating systems have been put into practical use from the viewpoint of quick start and energy saving. An electromagnetic induction heating type device has also been proposed.

a) Heat roller type fixing device The heat roller type fixing device is basically composed of a pressure roller pair of a fixing roller (heating roller) and a pressure roller, and the roller pair is rotated so that a mutual pressure contact portion of the roller pair is obtained. The recording material on which an unfixed toner image to be image-fixed is formed and supported is introduced and conveyed, and the unfixed toner image is formed by the heat of the fixing roller and the pressure of the fixing nip. It is heat-fixed on the surface of the recording material.

  In general, the fixing roller has an aluminum hollow metal roller as a base body (core metal), and a halogen lamp as a heat source is inserted and disposed in the inner space thereof. The temperature of the halogen lamp is controlled and controlled so that the temperature is maintained.

  In particular, as a fixing device of an image forming apparatus that performs full-color image formation that requires the ability to sufficiently heat-melt and mix colors of up to four toner image layers, a fixing roller core has a high heat capacity In addition, a rubber elastic layer for wrapping and uniformly melting the toner image around the outer periphery of the metal core is provided, and the toner image is heated through the rubber elastic layer. There is also a configuration in which a heat source is also provided in the pressure roller so that the pressure roller is also heated and temperature-controlled.

  However, even when the heat roller type fixing device is turned on and the energization of the halogen lamp, which is the heat source of the fixing device, is started at the same time, the heat capacity of the fixing roller is large and the fixing roller and the like are cooled down. A considerable waiting time (wait time) is required until the temperature reaches a predetermined fixing temperature from the state, and the quick start property is lacking. In addition, it is necessary to energize the halogen lamp and maintain the fixing roller at a predetermined temperature control state so that an image forming operation can be executed at any time even when the image forming apparatus is in a standby state (non-image output). There was a problem such as a large amount.

  Further, in the case of using a fixing roller having a particularly large heat capacity, such as the fixing device of the above-described full-color image forming apparatus, a delay occurs in the temperature control and the temperature increase on the surface of the fixing roller. Problems such as offset occurred.

  In order to solve such problems, in recent years, a heat roller fixing device having a good temperature responsiveness by using a thin roller to shorten the thermal time constant has been put into practical use.

b) Film Heating Type Fixing Device Film heating type fixing devices include, for example, JP-A-63-313182, JP-A-2-157878, JP-A-4-44075, JP-A-4-204980, and the like. Has been proposed.

  That is, a nip portion is formed by sandwiching a heat-resistant film (fixing film) between a ceramic heater as a heating element and a pressure roller as a pressure member, and the film in the nip portion and the pressure roller The recording material on which an unfixed toner image to be image-fixed is formed and supported is introduced and conveyed together with the film so that the heat of the ceramic heater is applied to the recording material through the film at the nip portion. Further, the unfixed toner image is fixed to the surface of the recording material by heat and pressure by the applied pressure of the nip portion.

  This film heating type fixing device can be configured as an on-demand type device using a ceramic heater and a film having a low heat capacity as a film, and energizes the ceramic heater as a heat source only when the image forming apparatus performs image formation. It is only necessary to generate heat at a predetermined fixing temperature, and the waiting time from the power-on of the image forming apparatus to the image forming executable state is short (quick start property), and the power consumption during standby is greatly reduced (saving) Power).

  However, a full-color image forming apparatus requiring a large amount of heat and a fixing device for a high-speed model have a difficulty in heat quantity.

c) Electromagnetic induction heating type fixing device Japanese Utility Model Laid-Open No. 51-109739 discloses an induction heating fixing device that induces a current in a fixing roller by magnetic flux and generates heat by Joule heat. This makes it possible to directly heat the fixing roller by utilizing the generation of the induced current, and achieves a fixing process that is more efficient than a heat roller type fixing device using a halogen lamp as a heat source.

  Further, in order to prevent noise of the induction heating fixing device, the resonance frequency resonated by the resonance capacitor and the coil is made out of the audible frequency band by operating the coil as shown in JP-A-9-80951 in parallel and lowering the inductance. Such a method has been proposed.

  Also, a high-efficiency fixing device that brings the exciting coil close to the fixing roller, which is a heating element, and concentrates the alternating magnetic flux distribution of the exciting coil in the vicinity of the fixing nip in order to obtain energy that acts on fixing at high density. Has been devised.

  Furthermore, examples of a fixing device in which an exciting coil is disposed outside the sleeve are disclosed in Japanese Patent Application Laid-Open Nos. 08-129313 and 08-220912.

  FIG. 9B shows a schematic configuration of an example of an electromagnetic induction heating type fixing apparatus in which the alternating magnetic flux distribution of the exciting coil is concentrated on the fixing nip to improve the efficiency.

  Reference numeral 10 denotes a cylindrical fixing film as an electromagnetic induction heat-generating rotating body having an electromagnetic induction heat-generating layer (conductor layer, magnetic layer, resistor layer).

  Reference numeral 16 denotes a saddle-shaped film guide member having a substantially semicircular arc shape in cross section, and the cylindrical fixing film 10 is loosely fitted outside the film guide member 16.

  Reference numeral 15 denotes a magnetic field generating means disposed inside the film guide member 16, which includes an exciting coil 18 and an E-type magnetic core (core material) 17.

  Reference numeral 30 denotes an elastic pressure roller. The fixing film 10 is sandwiched between the lower surface of the film guide member 16 so as to form a fixing nip portion N having a predetermined width with a predetermined pressing force, and are pressed against each other. The magnetic core 17 of the magnetic field generating means 15 is disposed so as to correspond to the fixing nip portion N.

  The pressure roller 30 is rotationally driven by the driving means M in the counterclockwise direction indicated by the arrow. A rotational force acts on the fixing film 10 by a frictional force between the pressure roller 30 and the outer surface of the fixing film 10 by the rotational driving of the pressure roller 30, and the inner surface of the fixing film 10 is a film in the fixing nip portion N. The outer periphery of the film guide member 16 is rotated in a clockwise direction indicated by an arrow while being in close contact with the lower surface of the guide member 16 with a peripheral speed substantially corresponding to the rotational peripheral speed of the pressure roller 30 (pressure roller driving). method).

  The film guide member 16 serves to pressurize the fixing nip, support the exciting coil 18 and the magnetic core 17 as the magnetic field generating means 15, support the fixing film 10, and transport stability when the film 10 rotates. To do. The film guide member 16 is a nonmagnetic and insulating member that does not obstruct the passage of magnetic flux, and a material that can withstand a high load is used.

  The exciting coil 18 generates an alternating magnetic flux by an alternating current supplied from an unillustrated exciting circuit. The alternating magnetic flux is intensively distributed in the fixing nip portion N by the E-type magnetic core 17 corresponding to the position of the fixing nip portion N. The alternating magnetic flux is applied to the electromagnetic induction heating layer of the fixing film 10 in the fixing nip portion N. Generate eddy currents. This eddy current generates Joule heat in the electromagnetic induction heating layer by the specific resistance of the electromagnetic induction heating layer.

  The electromagnetic induction heat generation of the fixing film 10 is concentrated in the fixing nip portion N where the alternating magnetic flux is intensively distributed, and the fixing nip portion N is heated with high efficiency.

  The temperature of the fixing nip portion N is controlled so that a predetermined temperature is maintained by controlling the current supply to the exciting coil 18 by a temperature control system including a temperature detection unit (not shown).

  Thus, the pressure roller 30 is driven to rotate, and the cylindrical fixing film 10 rotates around the outer periphery of the film guide member 16, and the fixing film 10 is supplied with power from the excitation circuit to the excitation coil 18 as described above. The recording material P on which the unfixed toner image t conveyed from the image forming unit (not shown) is formed in the state where the fixing nip portion N rises to a predetermined temperature and the temperature is adjusted by the electromagnetic induction heat generation. The image surface is introduced between the fixing film 10 and the pressure roller 30 in the fixing nip portion N, that is, facing the fixing film surface, and the image surface is in close contact with the outer surface of the fixing film 10 in the fixing nip portion N. The fixing nip portion N is nipped and conveyed together with the fixing film 10. In the process in which the recording material P is nipped and conveyed together with the fixing film 10 through the fixing nip N, the fixing film 10 is heated by electromagnetic induction heat generation, and the unfixed toner image t on the recording material P is heated and fixed. The When the recording material P passes through the fixing nip portion N, it is separated from the outer surface of the rotary fixing film 10 and discharged and conveyed.

FIG. 9A shows a conventional example in which an exciting coil is arranged outside. In FIG. 9A, 101 is a fixing sleeve, 108 is a fixing heating roller, 108a is a cored bar portion of the fixing heating roller, and aluminum is used as the material. Reference numeral 108b denotes a rubber layer of the fixing heating roller. Reference numeral 105 denotes an exciting coil for supplying fixing heating power to the fixing heating sleeve, reference numeral 106 denotes a thermo switch, and reference numeral 107 denotes a thermistor, each configured to measure the temperature of the fixing heating sleeve. A coil holder 104 holds the exciting coil. The coil holder is configured to have a thickness necessary for the standard to insulate the fixing sleeve as the user accessible portion and the exciting coil as the power source. The fixing heating sleeve 101 is pressed and held by bearings 116 at both ends while maintaining rotational slidability.
JP-A-63-313182 Japanese Patent Laid-Open No. 2-157878 JP-A-4-44075 JP-A-4-204980 Japanese Utility Model Publication No. 51-109739 Japanese Patent Laid-Open No. 9-80951 Japanese Patent Laid-Open No. 08-129313 Japanese Patent Laid-Open No. 08-220912

  However, in the conventional configuration, since the fixing sleeve has a large degree of freedom, when the fixing sleeve is heated by the exciting coil, a reaction force is generated by the magnetic field from the exciting coil and the eddy current generated in the sleeve, and the sleeve vibrates. There was a problem of doing. Furthermore, since the state of magnetic coupling between the fixing sleeve and the exciting coil varies due to the vibration of the fixing sleeve, there is a problem that it is difficult to perform stable power supply and stable heating.

  In addition, there is a problem that stable paper feeding is difficult because the trajectory is not fixed even when the fixing sleeve is rotationally driven by the fixing heating roller.

  Therefore, it is proposed to provide a mechanism that regulates the orbit of the sleeve inside the fixing sleeve. In particular, when the coil is arranged outside the sleeve, a sleeve guide made of heat-resistant resin is provided on the part facing the coil across the fixing sleeve, and it is attached to the sleeve guide and fixed to the fixing pressure roller as an integral unit. It is proposed to arrange a pressure mechanism that presses the sleeve to improve the fixing property.

  It is possible to perform stable heating and to construct an induction heating fixing device with low noise.

  As described above, by providing a sleeve guide at a position facing the excitation coil across the fixing heating sleeve, it is possible to regulate the distance of the fixing heating sleeve from the excitation coil and prevent vibration of the fixing heating sleeve. It becomes possible. For this reason, it is possible to stabilize the magnetic coupling between the fixing heating sleeve and the exciting coil to perform stable heating. Further, since it is possible to suppress the vibration of the fixing heating sleeve, it is possible to provide an induction heating fixing device with better image quality.

  Next, details of the present invention will be described in accordance with the description of the embodiments.

  FIG. 1 is a diagram that best represents the first embodiment of the present invention. In FIG. 1, reference numeral 101 denotes a fixing sleeve, which has a hollow cylindrical shape as shown. Reference numeral 101a denotes a metal layer which is a heating element of the fixing sleeve, and in addition to a magnetic metal such as iron, nickel and stainless steel, nonmagnetic stainless steel or aluminum is used. The sleeve axial direction and the paper transport direction are arranged at right angles so that the sleeve rotation direction becomes the paper transport direction, and the length of the sleeve is longer than the maximum sheet passing width of the apparatus. Reference numeral 101b denotes a silicon rubber layer, which is used for improving the fixing property. A release layer 101c coats the sleeve surface layer to improve the separation of the recording material such as toner from the sleeve. 101d is a coating layer for improving the slidability of the inner surface of the sleeve. A pressure member 102 is disposed in contact with the sleeve, presses the sleeve against the fixing pressure roller to form a fixing nip portion, and transmits the rotation of the fixing roller to the sleeve to frictionally drive the sleeve. Reference numeral 103 denotes a sliding plate for improving the slidability at the fixing nip portion. A coil holder 104 supports the fixing heating coil and ensures insulation between the sleeve and other user accessible parts and the fixing heating coil. A fixing heating coil 105 has a diameter of about 0.1 to 0.3 mm, and is a coil in which about 10 to 200 litz wires coated with an insulating film are wound several times to several dozen times. Is formed in the coil holder in a curved shape along the outer periphery of the sleeve as shown in the figure. The longitudinal direction of the coil is along the sleeve axial direction and is disposed at right angles to the paper transport direction, and the coil longitudinal direction is configured to be longer than the maximum sheet passing width of the apparatus. A resin pressing member 113 is provided to fix the exciting coil in close contact with the surface of the coil holder facing the fixing heating sleeve. In this embodiment, the resin pressing member 113 is fixed to the coil holder with screws, but may be configured to be attached without using screws. By configuring the exciting coil to be covered with the coil holder and the resin pressing member, the user can ensure safety so that the user does not touch the litz wire of the exciting coil. In order to prevent the Litz wire from being touched by the user even when the fine wire is broken, for example, if it is covered by the frame of the fixing device, a cutout portion for securing an air path may be provided in the pressing member.

  Reference numeral 106 denotes a thermo switch. In this embodiment, as a non-contact type configuration, the temperature of the fixing sleeve is detected by being attached to a part of the coil holder, and when the temperature reaches a predetermined temperature, the contact is cut by bimetal. Yes. Reference numeral 107 denotes a thermistor, which is disposed so as to contact the thermistor element from the outside of the fixing sleeve in order to detect the temperature of the fixing sleeve. Reference numeral 108 denotes a fixing heating roller. Reference numeral 108a denotes a cored bar portion of the fixing heating roller, which is made of a hollow or cylindrical metal. In general, aluminum is often used as the metal material 108a. A rubber layer 108b is formed of silicon rubber or the like. The rubber part 108b is configured to be longer than the maximum sheet passing width that the apparatus can pass through. The maximum width sheet is conveyed and reaches the nip, and the coefficient of friction at the sheet passing portion is caused by water vapor from the sheet. Even if it drops, the sleeve is driven and driven without slipping by the frictional force of the end.

  The metal layer of the fixing sleeve has a penetration depth in the frequency range of 20 kHz to several 100 kHz, which is the frequency range where induction heating is performed, in order to reduce heat capacity for the purpose of improving controllability and thermal response and to provide durability of the sleeve. The thickness is about 1 to several hundred times the thickness. Since the heat capacity of the rubber layer and the release layer is also small, the fixing sleeve needs to be thin. Therefore, the fixing sleeve has small rigidity and easily elastically deforms. Therefore, it is difficult to drive the fixing sleeve alone to rotate the fixing sleeve, and the driven mechanism can be driven by the fixing heating roller, the driving mechanism of the fixing heating roller, and the pressing mechanism of the fixing sleeve to the fixing heating roller. It is said.

  M is a motor, and the fixing heating roller is driven to rotate at a reduced speed so as to obtain an appropriate conveyance speed by a belt or gear train as a rotation transmission mechanism.

  FIG. 2 shows a cross-sectional view of the main part of the fixing device. In FIG. 2A, reference numerals 23a and 23b denote rotation guides for protecting the end portions of the fixing heating sleeve and smooth rotation of the fixing sleeve, and reference numeral 25 denotes a coil spring for pressurizing the fixing heating sleeve at the fixing nip portion. The pressure is distributed evenly from the 29 pressure reference planes to the left and right. The reference plane 29 may be constituted by the frame structure of the fixing device. As described above, in this embodiment, the length LR of the rubber portion 108b of the fixing roller in the fixing roller rotation axis direction is configured to be larger than the maximum sheet passing width of the apparatus.

  FIG. 3 shows the state of heat generation when heating is performed with such a configuration. Due to the alternating magnetic field generated by the exciting coil, an eddy current (induced current) flows in the metal layer 101a portion of the fixing heating sleeve, and the metal layer itself generates heat. FIG. 3 shows the heat distribution in the cross section of the central portion in the longitudinal direction of the sleeve. When the angle from the center of the sleeve is taken with the coil central part at 0 °, the distribution is as shown in the right figure of FIG. The horizontal axis is the calorific value Q, and the vertical axis is the angle. There are portions with a large amount of heat generation at two locations along the exciting coil. For reference, the distribution of electromagnetic waves inside the metal layer 101a of the fixing heating sleeve is shown in FIG. In the figure, the horizontal axis represents the thickness of the sleeve, and the vertical axis represents the strength of the electric field strength. The thickness of the metal layer outside the sleeve (the side close to the exciting coil) is 0, and the distance from the inside to the inside of the sleeve is taken along the horizontal axis.

  FIG. 5 shows a diagram that best represents the second embodiment of the present invention.

  In FIG. 5A, reference numeral 101 denotes a fixing sleeve, which has a hollow cylindrical shape as shown. The structure and configuration of the fixing sleeve are the same as those described in the first embodiment.

  A pressure member 102 is disposed in contact with the sleeve, presses the sleeve against the fixing pressure roller to form a fixing nip N portion, and transmits the rotation of the fixing roller to the sleeve to frictionally drive the sleeve.

  Reference numeral 109 denotes a sleeve guide that is inscribed in the sleeve at a position facing the fixing heating coil. As described in the first embodiment, the metal layer of the fixing sleeve is a thin layer in order to reduce the heat capacity and to provide durability, and has a small rigidity and easily elastically deforms.

  On the other hand, the fixing heating sleeve receives a force in a direction away from the exciting coil by a magnetic field generated by the exciting coil and an induced current (eddy current) flowing in the sleeve itself.

  Since the repulsive force is generated by driving the inverter, the vibration is generated at the inverter driving frequency. When jitter occurs during the operation of the inverter or there is a factor that causes the frequency division in the resonance mechanism of the sleeve, the vibration vibrates at a frequency obtained by dividing the inverter operating frequency. When this vibration frequency overlaps with the natural vibration frequency of the sleeve, a large vibration or resonance sound is generated.

  In addition, an inverter device (not shown) is used as the power source of the fixing device. When the inverter frequency is lowered, the power supplied to the fixing device increases. When the inverter frequency is increased, the power supplied to the fixing device decreases. Become. The temperature of the fixing heating sleeve is detected by the thermistor 107, and when the temperature of the fixing heating sleeve approaches the target temperature, the inverter device increases its frequency in order to reduce the power. For this reason, even if no vibration (resonance sound) is generated during the start-up operation in which a large power is supplied to the fixing device to raise the fixing heating sleeve temperature to the fixing temperature, the fixing heating is caused by the change in the inverter driving frequency accompanying the temperature control. The natural frequency of the sleeve and the inverter drive frequency may overlap and vibration (or resonance noise) may be generated.

  Furthermore, when the fixing heating sleeve moves away from the excitation coil, the magnetic coupling between the fixing heating sleeve and the excitation coil becomes weak. Therefore, the magnetic coupling becomes stronger or weaker with the vibration. As a result, a load fluctuation of the circuit occurs, and stable heating becomes difficult.

  Accordingly, the sleeve guide 109 is disposed as a member for preventing vibrations that contact the fixing heating sleeve to suppress vibration of the fixing heating sleeve and restrict escape of the fixing heating sleeve from the exciting coil, and a maximum distance regulating member between the exciting coil and the fixing heating sleeve. is doing.

  An example of 109 sleeve guides is shown in FIG. The sleeve guide has a bowl-like shape obtained by cutting out a part of a hollow cylinder having a curvature equal to or smaller than the inner diameter of the fixing heating sleeve so as to follow the inner diameter of the fixing heating sleeve, and the fixing heating sleeve temperature fixes the toner at the fixing temperature. Therefore, it is made of a heat resistant resin having heat resistance equal to or higher than the fixing temperature.

  Since the contact surface between the fixing heating sleeve and the sleeve guide must be slidable, the inner surface of the fixing heating sleeve can be coated with a material with excellent slidability and heat resistance such as PI (polyimide) or PTFE. good. On the other hand, the sleeve guide 109 has a rib in the axial direction of the fixing heating sleeve to reduce the contact area, and a high heat-resistant lubricant such as silicon grease is applied to the contact surface with the fixing heating sleeve to reduce the friction resistance. To keep it low.

  In order to efficiently guide the magnetic field from the exciting coil to the fixing and heating sleeve, the member 115 having a high magnetic permeability and a small loss may be arranged in the sleeve guide so that a magnetic path can be formed.

  Reference numeral 110 denotes a support member that couples the sleeve guide and the frame of the fixing device, supports the sleeve guide and defines the position of the sleeve guide, and presses the fixing heating sleeve against the fixing pressure roller to form a nip. It is a pressure member. In this embodiment, the sleeve guide and the pressure member are fastened with 111 screws at two positions on both ends as shown in FIG. 4, and the sleeve guide itself extends to the fixing nip portion N. The moving plate 103 is configured to be fitted. The coil holder and the sleeve guide of the fixing heating coil are fixed to the frame of the fixing device, and the facing surfaces of the sleeve guide and the coil holder are opposed to each other with a gap of about several tens of mm or less. Since the coil holder is disposed close to and opposed to the fixing heating sleeve, it is preferably a non-magnetic material or non-metallic material having heat resistance, and heat-resistant resin or the like is used. As described in the first embodiment, the exciting coil is a coil formed by rotating a litz wire, and 113 resin is used to fix the exciting coil in close contact with the fixing heating sleeve facing surface side of the coil holder. A pressing member made of metal is provided. The resin pressing member 113 is screwed in this embodiment, but may be configured to be attached without using screws. By configuring the exciting coil to be covered with the coil holder and the resin pressing member, the user can ensure safety so that the user does not touch the litz wire of the exciting coil. In order to prevent the Litz wire from being touched by the user even if the thin wire of the litz wire is broken, for example, if it is covered by the frame 120 of the fixing device, a cutout portion for securing an air path may be provided in the pressing member.

  Further, the contact surface of the coil holder with the exciting coil may be provided with a groove 112 such as to ensure air permeability. The direction of the groove may be the rotation direction of the fixing heating sleeve or the direction parallel to the fixing heating sleeve axis. Further, a rear end sleeve guide 114 is also provided inside the fixing sleeve on the downstream side of the fixing nip to stabilize the rotation path of the fixing heating sleeve so that the recording paper can be easily separated from the fixing heating sleeve after passing through the fixing nip. You may comprise as follows. With this configuration, since the degree of freedom of the position of the fixing heating sleeve in the direction approaching the fixing heating coil is lowered, the fixing heating sleeve can be made more difficult to vibrate.

  FIG. 7 shows the best representation of the third embodiment. The contents described in the first and second embodiments are omitted. In FIG. 4, reference numeral 701 denotes a thermistor. By using the internal thermistor as shown in FIG. 7, stable temperature detection can be performed without being affected by the accumulation of toner and paper powder. Furthermore, by detecting the temperature at the heated part, it is possible to achieve a structure with better thermal response and temperature controllability and to improve controllability when the sleeve stops. ing. An example of the configuration of the inscribed thermistor is shown in FIGS. 7A, 7B, and 7C, respectively.

  In FIG. 7A, reference numeral 701 denotes a thermistor chip, and reference numeral 702 denotes a thermistor mounting portion. Like the sleeve guide, a heat-resistant resin is used as a non-magnetic, non-metallic and high heat-resistant material. FIG. 7B shows a thermistor provided with an inscribed guide rail as a thermistor, and has a guide part 702a having an R at a smaller angle than the system inside the sleeve. Reference numeral 703 denotes a jumet wire that is a lead wire for drawing a signal from the thermistor chip, and reference numeral 704 denotes a lead frame that abuts the thermistor chip on the sleeve with an appropriate contact pressure. A thin stainless plate or the like is used. 705 is a heat-resistant sponge for holding the thermistor chip, and 706 is a screw hole for attaching the thermistor. A view in which such a thermistor is attached and incorporated in the apparatus is shown in FIG. In this way, the thermistor chip is configured to measure the temperature of the heating region. Further, the guide rail portion may be configured to be in smooth contact with the sleeve so as to further suppress the degree of freedom of the sleeve. FIG. 7C shows an example in which the thermistor is attached to the sleeve guide portion. In FIG. 7C, thermistor chips are arranged at two locations in the longitudinal direction of the sleeve to measure the temperature at the center and the temperature at the end. The edge temperature is detected outside the paper width Lmin and within the maximum paper passing width Lmax that the apparatus can pass.

  When the fixing sleeve has a sufficient thickness and strength, a support mechanism at the end of the sleeve may be supported by the bearing 116 as shown in FIG. 8 so that the rotation can be smoothly performed. Further, a gear may be arranged on the fixing heating sleeve itself so that the rotation of the motor is transmitted together with the fixing pressure roller. FIG. 8 shows an example in which a vibration preventing member is attached in such a system. In the figure, reference numeral 118 denotes a vibration preventing member, which has a structure in which a part of a hollow cylinder is cut out as shown in the figure, and is configured to be brought into contact with the inside of the fixing sleeve by a support member 117. The support member 117 may have a spring property, for example, a support mechanism using a coil spring. Reference numeral 110 denotes an attachment member for attaching the support member 117 to the frame of the fixing unit. As the material of the vibration preventing member 118, a heat resistant resin having a heat resistance higher than the fixing temperature is used. The vibration preventing member 118 may be provided with a groove as shown by the 109 sleeve guide in order to suppress the frictional resistance with the fixing sleeve.

The figure explaining 1st Example (A) Side model diagram of main part of fixing device as heating device, (b) Transverse side model diagram of main part of fixing device as heating device Diagram showing the relationship between magnetic field generation means and calorific value Q Graph showing the relationship between heat generation layer depth and electromagnetic wave intensity The figure explaining 2nd Example Diagram showing sleeve guide structure and installation example The figure explaining the 3rd example The figure explaining the 4th example A figure showing a conventional example

Claims (9)

  In an image forming apparatus having an induction heating type fixing device, a fixing heating sleeve, an excitation coil necessary for performing induction heating, a fixing pressure roller, and a system for heating by an excitation coil from the outside of the fixing heating sleeve An image forming apparatus comprising: an induction heating fixing device having a sleeve pressing member inside the fixing heating sleeve.   In an image forming apparatus having an induction heating type fixing device, a fixing heating sleeve, an excitation coil necessary for performing induction heating, a fixing pressure roller, and a system for heating by an excitation coil from the outside of the fixing heating sleeve The fixing heating sleeve has a sleeve pressure member, has a means for rotating the pressure roller, and includes an induction heating fixing device in which the fixing heating sleeve is driven by rotating the pressure roller. An image forming apparatus.   In an image forming apparatus having an induction heating type fixing device, a fixing heating sleeve, an excitation coil necessary for performing induction heating, a fixing pressure roller, and a system for heating by an excitation coil from the outside of the fixing heating sleeve The fixing heating sleeve has a sleeve pressure member, has a means for rotating the pressure roller, and has a configuration in which the fixing heating sleeve is driven by rotating the pressure roller. An image forming apparatus comprising: an induction heating fixing device in which a contact width of a fixing sleeve is larger than a maximum sheet passing region of the apparatus.   In an image forming apparatus having an induction heating type fixing device, a fixing heating sleeve, an excitation coil necessary for performing induction heating, a fixing pressure roller, and a system for heating by an excitation coil from the outside of the fixing heating sleeve The fixing heating sleeve has a sleeve pressure member, has a means for rotating the pressure roller, and has a configuration in which the fixing heating sleeve is driven by rotating the pressure roller. Provided is an induction heating fixing device in which the contact width of the fixing sleeve is larger than the maximum sheet passing area of the apparatus and the longitudinal size of the excitation coil is larger than the maximum sheet passing area of the apparatus. An image forming apparatus.   In an image forming apparatus having an induction heating type fixing device, it has a fixing heating sleeve and an excitation coil necessary for performing induction heating, has a fixing pressure roller, and is heated by the excitation coil from the outside of the fixing heating sleeve. An image forming apparatus comprising: an induction heating fixing device having a sleeve pressing member inside a fixing heating sleeve and having a sleeve guide provided at a position facing a coil inside the fixing heating sleeve.   In an image forming apparatus having an induction heating type fixing device, it has a fixing heating sleeve and an excitation coil necessary for performing induction heating, has a fixing pressure roller, and is heated by the excitation coil from the outside of the fixing heating sleeve. In this system, a sleeve pressure member is provided inside the fixing heating sleeve, a sleeve guide is provided at a position facing the coil inside the fixing heating sleeve, and a sleeve guide is also provided inside the fixing heating sleeve at the rear end of the nip. An image forming apparatus comprising a heat fixing device.   The image forming apparatus according to claim 1, further comprising an induction heating fixing device having at least one temperature measuring element that is inscribed inside the fixing heating sleeve and measures temperature. Forming equipment.   4. The image forming apparatus according to claim 1, further comprising at least two temperature measuring elements that are inscribed in the inside of the fixing heating sleeve and measure the temperature, and the at least one temperature detecting element passes through the apparatus. An image forming apparatus, wherein the image forming apparatus is arranged in a minimum paper passing area where paper can be passed, and at least one temperature detecting element is placed outside the minimum paper passing area where paper can pass through the apparatus.   6. The image forming apparatus according to claim 1, further comprising an induction heating fixing device in which a high magnetic permeability material is disposed at a position facing the exciting coil inside the fixing heating sleeve. apparatus.

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