JP6248736B2 - Heating device, fixing device and image forming apparatus - Google Patents

Description

  The present invention relates to a heating device, a fixing device, and an image forming apparatus.

  In Patent Document 1, a heat generating member that contacts the fixing rotator at a position different from the nip portion and heats the fixing rotator, and a heat generating member so that the contact pressure or the facing distance of the heat generating member to the fixing rotator is variable. There is disclosed a fixing device including a movable unit that moves the movable member.

  In Patent Document 2, a fixing belt having an exciting coil, a heat generating layer, a temperature-sensitive magnetic member in which the magnetic permeability starts to decrease continuously from the magnetic permeability change start temperature, and the temperature-sensitive magnetic member are brought into contact with and separated from the fixing belt. A fixing device having a contact / separation mechanism is disclosed.

JP 2012-3187 A JP 2009-282413 A

  An object of this invention is to suppress the variation in the temperature distribution in the circumferential direction of the heat generating body which contacts the inner peripheral surface of an annular belt.

  According to the first aspect of the present invention, an annular belt, a magnetic field generator that is disposed outside the belt, generates a magnetic field, and is disposed opposite to the magnetic field generator across the belt, and generates heat by electromagnetic induction of the magnetic field. A heating element that contacts the inner peripheral surface of the belt, and a separation mechanism that separates the other end side in the circumferential direction from the inner peripheral surface of the belt to the axial center side of the belt with the circumferential one end side of the heating element as a fulcrum. And a moving mechanism that moves a portion of the magnetic field generating portion facing the other end in the circumferential direction toward the other end in the circumferential direction in accordance with the separating operation of the heating element by the separating mechanism. .

  According to a second aspect of the present invention, there is provided the heating apparatus according to the first aspect, and a pressure member that pressurizes a recording medium between the belt and the pressure by the pressure member and the heating by the belt. Fix the image on the recording medium.

  According to a third aspect of the present invention, there is provided an image forming portion that forms an image on a recording medium, and a fixing device according to the second aspect that fixes the image formed on the recording medium to the recording medium.

  According to the configuration of claim 1 of the present invention, variation in the temperature distribution in the circumferential direction of the heating element can be suppressed as compared with the case where the moving mechanism in the present configuration is not provided.

  According to the configuration of the second aspect of the present invention, it is possible to suppress the fixing failure due to the variation in the temperature distribution in the circumferential direction of the heating element as compared with the case where the heating device in the present configuration is not provided.

  According to the configuration of the third aspect of the present invention, it is possible to suppress the image defect due to the fixing failure as compared with the case where the fixing device in the present configuration is not provided.

1 is a schematic diagram illustrating a configuration of an image forming apparatus according to an exemplary embodiment. FIG. 2 is a side sectional view showing a configuration of a fixing device according to the present embodiment. FIG. 3 is a side sectional view showing a state in which the heat generating plate is separated from the heating belt in the fixing device shown in FIG. 2. It is a perspective view which shows the structure of the moving mechanism which concerns on this embodiment. It is a side view which shows the structure of the moving mechanism which concerns on this embodiment.

  Below, an example of an embodiment concerning the present invention is described based on a drawing.

(Configuration of image forming apparatus 10)
First, the configuration of the image forming apparatus 10 will be described. FIG. 1 is a schematic diagram illustrating a configuration of the image forming apparatus 10.

  As shown in FIG. 1, the image forming apparatus 10 includes an image forming apparatus main body 11 (housing) in which each component is housed. Inside the image forming apparatus main body 11, a plurality of storage units 12 that store recording media P such as paper, an image forming unit 14 that forms images on the recording media P, and images formed on the recording media P are stored. And a fixing device 60 for fixing the recording medium P. In the image forming apparatus main body 11, a transport unit 16 that transports the recording medium P from the storage unit 12 to the image forming unit 14 and a control unit 20 that controls the operation of each unit of the image forming apparatus 10 are further provided. It has been. Further, a discharge unit 18 for discharging the recording medium P on which the image is fixed by the fixing device 60 is provided on the upper portion of the image forming apparatus main body 11.

  The image forming unit 14 includes image forming units 22Y, 22M, 22C, and 22K (hereinafter referred to as 22Y to 22K) that form toner images of colors of yellow (Y), magenta (M), cyan (C), and black (K). And an intermediate transfer belt 24 to which the toner images formed by the image forming units 22Y to 22K are transferred. Further, the image forming unit 14 transfers the toner images formed by the image forming units 22 </ b> Y to 22 </ b> K to the intermediate transfer belt 24 and transferred to the intermediate transfer belt 24 by the first transfer roll 26. And a second transfer roll 28 for transferring the toner image from the intermediate transfer belt 24 to the recording medium P. The image forming unit 14 is not limited to the above-described configuration, and may be another configuration as long as it forms an image on the recording medium P.

  The image forming units 22 </ b> Y to 22 </ b> K are disposed inside the image forming apparatus main body 11 while being inclined with respect to the horizontal direction. Each of the image forming units 22Y to 22K has a photoreceptor 32 that rotates in one direction (for example, the counterclockwise direction in FIG. 1). Since the image forming units 22Y to 22K are configured in the same manner, the reference numerals of the respective portions in the image forming units 22M, 22C, and 22K are omitted in FIG.

  Around each photoconductor 32, a charging roll 23 as a charging device for charging the photoconductor 32 and the photoconductor 32 charged by the charge roll 23 are exposed in order from the upstream side in the rotation direction of the photoconductor 32. An exposure device 36 that forms an electrostatic latent image on 32 and a developing device 38 that develops the electrostatic latent image formed on the photoreceptor 32 by the exposure device 36 to form a toner image are provided.

  The exposure device 36 is configured to form an electrostatic latent image based on the image signal sent from the control unit 20. Examples of the image signal sent from the control unit 20 include an image signal acquired by the control unit 20 from an external device.

  The developing device 38 includes a developer supply body 38A that supplies the developer to the photoconductor 32, and a plurality of transport members 38B that transport the developer applied to the developer supply body 38A while stirring.

  The intermediate transfer belt 24 is formed in an annular shape and is disposed on the upper side of the image forming units 22Y to 22K. On the inner peripheral side of the intermediate transfer belt 24, winding rolls 42, 43, and 44 around which the intermediate transfer belt 24 is wound are provided. The intermediate transfer belt 24 circulates (rotates) in one direction (for example, the clockwise direction in FIG. 1) while being in contact with the photoreceptor 32, for example, when the winding roll 44 is rotationally driven. . The winding roll 42 is an opposing roll that faces the second transfer roll 28.

  The first transfer roll 26 faces the photoconductor 32 with the intermediate transfer belt 24 interposed therebetween. A space between the first transfer roll 26 and the photoconductor 32 is a first transfer position where the toner image formed on the photoconductor 32 is transferred to the intermediate transfer belt 24.

  The second transfer roll 28 faces the winding roll 42 with the intermediate transfer belt 24 interposed therebetween. A space between the second transfer roll 28 and the winding roll 42 is a second transfer position where the toner image transferred to the intermediate transfer belt 24 is transferred to the recording medium P.

  The transport unit 16 is disposed along the transport path 48 and is transported along a transport roll 48 for transporting the recording medium P stored in the storage section 12, a transport path 48 for transporting the recording medium P transported to the transport roll 46. And a plurality of transport rolls 50 for transporting the recording medium P fed by the roll 46 to the second transfer position.

  A fixing device 60 that fixes the toner image transferred to the recording medium P by the second transfer roll 28 to the recording medium P is provided on the downstream side in the transport direction from the second transfer position. On the downstream side of the fixing device 60 in the transport direction, a plurality of transport rolls 52 are provided for transporting the recording medium P on which the toner image is fixed toward the discharge unit 18. A specific configuration of the fixing device 60 will be described later.

  Next, an image forming operation for forming an image on the recording medium P in the image forming apparatus 10 according to the present embodiment will be described.

  In the image forming apparatus 10 according to the present embodiment, the recording medium P sent out from the storage unit 12 by the sending roll 46 is sent to the second transfer position by the plurality of conveying rolls 50.

  On the other hand, in the image forming units 22 </ b> Y to 22 </ b> K, the photosensitive member 32 charged by the charging roll 23 is exposed by the exposure device 36 to form an electrostatic latent image on the photosensitive member 32. The electrostatic latent image is developed by the developing device 38 to form a toner image on the photoreceptor 32. The color toner images formed by the image forming units 22Y to 22K are superimposed on the intermediate transfer belt 24 at the first transfer position to form a color image. Then, the color image formed on the intermediate transfer belt 24 is transferred to the recording medium P at the second transfer position.

  The recording medium P to which the toner image has been transferred is conveyed to the fixing device 60, and the transferred toner image is fixed by the fixing device 60. The recording medium P on which the toner image is fixed is discharged to the discharge unit 18 by the transport roll 52. As described above, a series of image forming operations are performed.

(Configuration of Fixing Device 60)
Next, the configuration of the fixing device 60 according to the present embodiment will be described. FIG. 2 is a cross-sectional side view showing the configuration of the fixing device 60 according to the present embodiment.

  As shown in FIG. 2, the fixing device 60 includes a heating belt 64 (an example of a belt), a pressure roll 66 (an example of a pressure member), a heating device 70 that heats the heating belt 64 by electromagnetic induction, It has. In the fixing device 60, the recording medium P introduced between the heating belt 64 and the pressure roll 66 is pressed by the pressure roll 66 and heated by the heating belt 64, thereby fixing the toner image on the recording medium P. Let

  The heating device 70 includes an electromagnetic induction coil 72 (an example of a magnetic field generation unit) that generates a magnetic field, a holding member 74 that holds the electromagnetic induction coil 72, and a magnetic body 76. The holding member 74 is disposed on the side opposite to the pressure roll 66 side with respect to the heating belt 64 (the right side in FIG. 2). The holding member 74 has a length along the axial direction of the heating belt 64 and is formed in a substantially arc shape along the outer peripheral surface of the heating belt 64. A shaft 74 </ b> S protrudes from the holding member 74 toward the side opposite to the heating belt 64 (the right side in FIG. 2).

  An electromagnetic induction coil 72 is wound around the shaft portion 74S a plurality of times. The electromagnetic induction coil 72 is held by the holding member 74 while being wound around the shaft portion 74S. One end in the axial direction of the electromagnetic induction coil 72 held by the holding member 74 is opposed to the outer peripheral surface of the heating belt 64 with the holding member 74 interposed therebetween.

  The magnetic body 76 is disposed on the opposite side of the holding member 74 from the heating belt 64 (on the right side in FIG. 2). The magnetic body 76 is formed in a substantially arc shape along the outer peripheral surface of the holding member 74.

  Furthermore, the heating device 70 includes a heating plate 80 (an example of a heating element) that generates heat by electromagnetic induction of the electromagnetic induction coil 72, and a contact plate 82 that contacts the heating plate 80. The heat generating plate 80 and the contact plate 82 are disposed on the inner peripheral side of the heating belt 64.

  The heat generating plate 80 faces the electromagnetic induction coil 72 with the heating belt 64 interposed therebetween, and has a length along the axial direction of the heating belt 64. The heat generating plate 80 is curved in an arc shape along the inner peripheral surface of the heating belt 64, and is in contact with the inner peripheral surface of the heating belt 64 along the circumferential direction of the heating belt 64.

  The heat generating plate 80 generates heat by electromagnetic induction caused by a magnetic field generated when a current flows through the electromagnetic induction coil 72. In the present embodiment, the heating belt 64 itself also generates heat due to the electromagnetic induction. A metal material that generates heat by electromagnetic induction by the magnetic field of the electromagnetic induction coil 72 is used for the heat generating plate 80. As the metal material, for example, iron, nickel, cobalt, SUS, or an alloy thereof is used.

  Similar to the heat generating plate 80, the contact plate 82 has a length along the axial direction of the heating belt 64. The contact plate 82 is curved in an arc shape along the inner peripheral surface of the heat generating plate 80, and is in contact with the inner peripheral surface of the heat generating plate 80. Thereby, the contact plate 82 moves heat in the length direction of the heat generating plate 80 (the axial direction of the heating belt 64), and suppresses variation in temperature distribution in the length direction of the heat generating plate 80. That is, the contact plate 82 has a function of making the temperature distribution of the heat generating plate 80 uniform. The contact plate 82 has a function of increasing the heat capacity of the contact plate 82 and the heat generating plate 80 as a whole by contacting and overlapping the heat generating plate 80. The contact plate 82 is made of a metal material having better thermal conductivity than the heat generating plate 80. For example, aluminum or copper is used as the metal material.

  On the inner peripheral side of the heating belt 64, a pad 86 that sandwiches the heating belt 64 with the pressure roll 66 and a support member 88 that supports the pad 86 are further provided. The support member 88 is provided with a separation mechanism 90 that separates the one end 80 </ b> A in the circumferential direction of the heat generating plate 80 from the inner peripheral surface of the heating belt 64 toward the axial center side of the heating belt 64. Yes.

  The separation mechanism 90 includes a support portion 91 that supports the heat generating plate 80 and the contact plate 82, and a compression spring 92 as an urging member. Further, the separation mechanism 90 includes a cam 95 rotatably supported by the support member 88, a rod 93 movably supported by the support member 88, and a compression spring 94 as an urging member attached to the rod 93. ,have.

  The support portion 91 is provided on the inner peripheral side of the heat generating plate 80, and is disposed along the inner peripheral surface of the heat generating plate 80 so as to face the inner peripheral surface of the heat generating plate 80. One end 91 </ b> A in the circumferential direction of the support portion 91 is fixed to the one end 80 </ b> A in the circumferential direction of the heat generating plate 80 and the one end 82 </ b> A in the circumferential direction of the contact plate 82. On the other hand, the other circumferential end 91B of the support portion 91 is fixed to the other circumferential end 80B side of the heat generating plate 80 and the other circumferential end 82B side of the contact plate 82.

  Furthermore, the support portion 91 is configured such that the other end portion 91B in the circumferential direction is movable in the A direction and the B direction integrally with the heat generating plate 80 and the contact plate 82 with the one end portion 91A in the circumferential direction as a fulcrum.

  The other end 91B in the circumferential direction of the support portion 91 moves in the A direction from the position shown in FIG. 2, so that the other end 80B in the circumferential direction of the heat generating plate 80 is supported on the one end 80A in the circumferential direction of the heat generating plate 80 as a fulcrum. The side is separated from the inner peripheral surface of the heating belt 64 toward the axial center side of the heating belt 64. FIG. 3 shows a state where the other circumferential end 80 </ b> B side of the heat generating plate 80 is separated from the inner peripheral surface of the heating belt 64.

  Further, the other circumferential end 91B of the support portion 91 moves in the B direction from the position shown in FIG. 3, so that the circumferential other end 80B side of the heating plate 80 is supported on the circumferential one end 80A side. Rotating, the other circumferential end 80B side of the heat generating plate 80 comes into contact with the inner circumferential surface of the heating belt 64. FIG. 2 shows a state where the other circumferential end 80B side of the heat generating plate 80 is in contact with the inner peripheral surface of the heating belt 64.

  The compression spring 92 is provided on the support member 88, and pushes (biases) the other circumferential end 91B of the support portion 91 in the B direction.

  Specifically, the rod 93 is supported by a support member 88 such that an intermediate portion in the axial direction is movable in the axial direction (C direction and D direction) of the rod 93.

  The tip end side (one axial end side) of the rod 93 penetrates the support portion 91 so as to be movable in the axial direction of the rod 93 with respect to the support portion 91. A protruding portion 96 that protrudes radially outward is provided at the tip of the rod 93. A protruding portion 97 that protrudes outward in the radial direction is also provided at the base end of the rod 93. The outer peripheral surface of the cam 95 is in contact with the end surface 97 </ b> A of the overhang portion 97.

  The compression spring 94 attached to the rod 93 pushes the bulging portion 97 of the rod 93 in the D direction (biased). The pushing force (biasing force) of the compression spring 94 is larger than the pushing force (biasing force) of the compression spring 92.

  The cam 95 is fixed to the camshaft 98, and the rotational position (the rotation shown in FIG. 2) where the long diameter portion of the cam 95 contacts the end surface 97A of the overhanging portion 97 by the driving force from the driving portion 200 (see FIG. 4). Position) and a rotational position (rotational position shown in FIG. 3) where the short-diameter portion of the cam 95 contacts the end surface 97A of the overhanging portion 97, the cam shaft 98 rotates. As shown in FIG. 4, the driving force from the driving unit 200 is transmitted to the gear 206 provided on the cam shaft 98 via the plurality of gears 202 and 204, and the cam 95 (see FIG. 2). Rotate.

  In the separation mechanism 90, when the cam 95 rotates from the rotational position shown in FIG. 2 to the rotational position shown in FIG. 3, the rod 93 moves in the D direction by the pressing force of the compression spring 94. When the rod 93 moves in the D direction, the projecting portion 96 provided at the tip of the rod 93 hits the support portion 91 and moves the support portion 91 in the A direction against the pressing force of the compression spring 92. As a result, the other circumferential end 80 </ b> B side of the heat generating plate 80 moves to the axial center side of the heating belt 64 and is separated from the heating belt 64.

  On the other hand, when the cam 95 rotates from the rotational position shown in FIG. 3 to the rotational position shown in FIG. 2, the rod 93 moves in the C direction against the pressing force of the compression spring 94. When the rod 93 moves in the C direction, the rod 93 that restricts the movement of the support portion 91 in the B direction also moves in the C direction. As a result, the support portion 91 is moved in the B direction by the pressing force of the compression spring 92, and the entire heat generating plate 80 including the other circumferential end 80 </ b> B side contacts the heating belt 64.

  Further, the heating device 70 moves the facing portion 72A of the electromagnetic induction coil 72 facing the other end 80B in the circumferential direction of the electromagnetic induction coil 72 to the other end 80B side in the circumferential direction (with the separation mechanism 90 separating the heating plate 80). A moving mechanism 100 is provided for moving to the left side in FIG.

  As shown in FIGS. 4 and 5, the moving mechanism 100 includes the holding member 74 that holds the electromagnetic induction coil 72, the compression spring 102, and the link member 110. 4 and 5, the one end side in the longitudinal direction of the holding member 74 is shown.

  On the upper end 74A side and the lower end 74B side of the holding member 74, recesses 75A and 75B that open to the heating belt 64 side (left side in FIG. 5) are formed. A cylindrical projecting portion 65 (pin) projecting from the side plate 63 constituting the housing 62 of the fixing device 60 is fitted into the recessed portion 75A. Thereby, the holding member 74 is supported by the housing 62 so as to be rotatable around the axis of the protruding portion 65.

  Similarly, the other end side in the longitudinal direction of the holding member 74 is also supported by the housing 62 so as to be rotatable by the protruding portion. In FIG. 5, the illustration of the side plate 63 is omitted, and the configuration of the moving mechanism 100 is schematically illustrated.

  Further, the holding member 74 is attached to the image forming apparatus main body 11 on the right side in FIG. 5, and a unit including the heating belt 64, the pressure roll 66, and the housing 62 is removed from the image forming apparatus main body 11 on the left side in FIG. 5. It can be pulled out (taken out). When the unit is pulled out, the projecting portion 65 and the roller 116 described later come out from the recesses 75A and 75B.

  Since the holding member 74 is supported rotatably around the axis of the protrusion 65, the holding member 74 has the upper end 74A side as a fulcrum and the lower end 74B side integrally with the electromagnetic induction coil 72, and the direction E in FIG. It can move in the F direction.

  The compression spring 102 is disposed on the opposite side of the holding member 74 from the heating belt 64 (the right side in FIG. 5). The compression spring 102 pushes (holds) the holding member 74 in the direction E of FIG.

  In the link member 110, a long hole 112 having a length in the longitudinal direction is formed in an intermediate portion in the longitudinal direction. As shown in FIG. 4, a pin 67 protruding from the side plate 63 to the outside of the side plate 63 is inserted into the long hole 112. As a result, the link member 110 can rotate around the pin 67 and can move within a range in which the pin 67 moves in the longitudinal direction of the long hole 112.

  One end portion in the longitudinal direction of the link member 110 is rotatably connected by a connecting shaft 118 at a position eccentric with respect to the gear 204. A roller 116 disposed inside the side plate 63 is rotatably provided at the other longitudinal end of the link member 110. The roller 116 enters the recess 75 </ b> B of the holding member 74.

  With the driving force from the drive unit 200 (see FIG. 4), the connecting shaft 118 is positioned on the holding member 74 side (the right side in FIG. 5) (the rotating position shown in FIG. 5A), and the connecting shaft 118 is The gear 204 rotates between a rotation position (rotation position shown in FIG. 5B) located on the opposite side (left side in FIG. 5) to the holding member 74 side.

  The gear ratio between the gear 204 and the gear 206 is adjusted so that the cam 95 is located at the rotational position shown in FIG. 2 when the gear 204 is located at the rotational position shown in FIG. Similarly, the gear ratio between the gear 204 and the gear 206 is adjusted so that the cam 95 is located at the rotational position shown in FIG. 3 when the gear 204 is located at the rotational position shown in FIG. . In this embodiment, the gear ratio between the gear 204 and the gear 206 is 1, and when the gear 204 rotates 180 °, the gear 206 also rotates 180 °.

  In the moving mechanism 100, when the gear 204 rotates from the rotational position shown in FIG. 5A to the rotational position shown in FIG. 5B, the link member 110 moves to the gear 204 side with respect to the holding member 74 (left side in FIG. 5). Move to. When the link member 110 moves to the left side in FIG. 5, the holding member 74 moves in the E direction by the pressing force of the compression spring 102. Thereby, the facing portion 72 </ b> A of the electromagnetic induction coil 72 approaches the heating belt 64. At this time, since the cam 95 also rotates from the rotational position shown in FIG. 2 to the rotational position shown in FIG. 3, the other circumferential end 80 </ b> B side of the heat generating plate 80 moves toward the axial center side of the heating belt 64 as described above. Move and move away from the heating belt 64.

  Further, when the gear 204 rotates from the rotational position shown in FIG. 5B to the rotational position shown in FIG. 5A, the link member 110 moves to the holding member 74 side (right side in FIG. 5) with respect to the gear 204. When the link member 110 moves to the right side in FIG. 5, the holding member 74 moves in the F direction against the pressing force of the compression spring 102. Thereby, the facing portion 72 </ b> A of the electromagnetic induction coil 72 approaching the heating belt 64 is separated from the heating belt 64. At this time, since the cam 95 also rotates from the rotational position shown in FIG. 3 to the rotational position shown in FIG. 2, the entire heating plate 80 including the circumferential other end 80 </ b> B side becomes the heating belt 64 as described above. Contact.

(Operation of this embodiment)
Next, the operation of this embodiment will be described.
In the present embodiment, for example, in the initial stage of operation of the fixing device 60, the heating plate 80 is separated from the heating belt 64 in order to quickly heat the heating belt 64 to a predetermined temperature. Each of the plates 80 is heated by electromagnetic induction. Thereafter, the heating plate 80 is brought into contact with the heating belt 64, and heat is supplied from the heating plate 80 to the heating belt 64, so that the heating belt 64 is maintained at a predetermined temperature. The purpose of separating the heating plate 80 from the heating belt 64 is not limited to this purpose.

  Specifically, the heat generating plate 80 is separated from the heating belt 64 as follows. That is, as shown in FIG. 4, the driving force from the drive unit 200 is transmitted to the gear 206 provided on the cam shaft 98 via the plurality of gears 202 and 204, and the cam 95 is shown in FIG. It rotates from the rotational position to the rotational position shown in FIG.

  When the cam 95 rotates from the rotational position shown in FIG. 2 to the rotational position shown in FIG. 3, the rod 93 moves in the D direction by the pressing force of the compression spring 94. When the rod 93 moves in the D direction, the projecting portion 96 provided at the tip of the rod 93 hits the support portion 91 and moves the support portion 91 in the A direction against the pressing force of the compression spring 92. As a result, the other circumferential end 80 </ b> B side of the heat generating plate 80 moves to the axial center side of the heating belt 64 and is separated from the heating belt 64.

  At this time, the gear 204 rotates from the rotational position shown in FIG. 5 (A) to the rotational position shown in FIG. 5 (B). When the gear 204 rotates from the rotational position shown in FIG. 5A to the rotational position shown in FIG. 5B, the link member 110 moves to the gear 204 side (left side in FIG. 5) with respect to the holding member 74. When the link member 110 moves to the left side in FIG. 5, the holding member 74 moves in the E direction by the pressing force of the compression spring 102. Thereby, the facing portion 72 </ b> A of the electromagnetic induction coil 72 approaches the heating belt 64.

  Specifically, the heating plate 80 separated from the heating belt 64 contacts the heating belt 64 as follows. That is, when the cam 95 is rotated from the rotational position shown in FIG. 3 to the rotational position shown in FIG. 2 by the driving force from the driving unit 200, the rod 93 moves in the C direction against the pressing force of the compression spring 94. To do. When the rod 93 moves in the C direction, the rod 93 that restricts the movement of the support portion 91 in the B direction also moves in the C direction. As a result, the support portion 91 is moved in the B direction by the pressing force of the compression spring 92, and the entire heat generating plate 80 including the circumferential other end 80 </ b> B side comes into contact with the heating belt 64.

  At this time, the gear 204 rotates from the rotational position shown in FIG. 5B to the rotational position shown in FIG. 5A by the driving force from the driving unit 200. When the gear 204 rotates from the rotational position shown in FIG. 5B to the rotational position shown in FIG. 5A, the link member 110 moves to the holding member 74 side (right side in FIG. 5) with respect to the gear 204. When the link member 110 moves to the right side in FIG. 5, the holding member 74 moves in the F direction against the pressing force of the compression spring 102. Thereby, the facing portion 72 </ b> A of the electromagnetic induction coil 72 approaching the heating belt 64 is separated from the heating belt 64.

  As described above, in the present embodiment, the other circumferential end 80B side of the heat generating plate 80 moves to the axial center side of the heating belt 64 and is separated from the heating belt 64, but in conjunction with this separation operation, the electromagnetic induction coil The opposed portion 72 </ b> A of 72 also approaches the heating belt 64. For this reason, the variation in the distance in the circumferential direction of the heat generating plate 80 between the heat generating plate 80 and the electromagnetic induction coil 72 is smaller than in the configuration in which the electromagnetic induction coil 72 does not move. For this reason, variation in the temperature distribution in the circumferential direction of the heat generating plate 80 electromagnetically heated by the electromagnetic induction coil 72 is suppressed. Therefore, when the heat generating plate 80 separated from the heating belt 64 contacts the heating belt 64 again, the amount of heat supplied from the heat generating plate 80 to the heating belt 64 is suppressed from varying in the circumferential direction of the heat generating plate 80. .

  In the present embodiment, the heat generating plate 80 is spaced from the inner peripheral surface of the heating belt 64 with the circumferential one end 80A side as a fulcrum, but is not limited thereto. That is, the heat generating plate 80 may have a configuration in which the circumferential one end 80A side is separated from the inner peripheral surface of the heating belt 64 with the circumferential other end 80B side as a fulcrum.

  In the present embodiment, the separation mechanism 90 is configured using the cam 95. However, the present invention is not limited to this, and the separation mechanism may be configured using other mechanical elements.

  Moreover, in this embodiment, although the moving mechanism 100 was comprised using the link member 110, it is not restricted to this, You may comprise a moving mechanism using another machine element.

  The present invention is not limited to the above-described embodiment, and various modifications, changes, and improvements can be made without departing from the spirit of the present invention. For example, the modification examples described above may be appropriately combined.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 14 Image forming part 60 Fixing apparatus 64 Heating belt (an example of a belt)
66 Pressure roll (an example of a pressure member)
70 Heating device 72 Electromagnetic induction coil (an example of a magnetic field generator)
80 Heating plate (example of heating element)
90 Separating mechanism 100 Moving mechanism

Claims (3)

An annular belt,
A magnetic field generator disposed outside the belt and generating a magnetic field;
A heating element that is disposed opposite to the magnetic field generation unit across the belt, generates heat by electromagnetic induction of the magnetic field, and contacts an inner peripheral surface of the belt;
A separation mechanism that separates one end in the circumferential direction of the heating element from the inner peripheral surface of the belt toward the axial center side of the belt, with one end in the circumferential direction as a fulcrum;
A moving mechanism for moving a portion of the magnetic field generating portion facing the other end in the circumferential direction toward the other end in the circumferential direction along with the separating operation of the heating element by the separating mechanism;
A heating device comprising: A heating device according to claim 1;
A pressurizing member that pressurizes the recording medium with the belt;
With
A fixing device that fixes an image on the recording medium by pressing with the pressing member and heating with the belt. An image forming unit for forming an image on a recording medium;
The fixing device according to claim 2, wherein an image formed on the recording medium is fixed on the recording medium;
An image forming apparatus comprising:

Images