JP6617611B2 - Fixing apparatus and image forming apparatus - Google Patents

Description

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

  A heating member having a heater composed of a flat substrate, and a pressure member that forms a heating nip by pressing the heater and a film between the electrodes, and the electrode portion is on one end side in the rotation axis direction of the heating member. The provided fixing device is conventionally known (see, for example, Patent Document 1).

JP 2000-106265 A

  The present invention provides a fixing device capable of reducing the size of the apparatus itself as compared with a configuration in which an electrode portion is formed on one end side in the rotation axis direction of the fixing member in a sheet-like heating member that heats a rotating endless belt-shaped fixing member. The purpose is to obtain.

  In order to achieve the above object, a fixing device according to a first aspect of the present invention is a sheet-like member in the rotational axis direction of an endless belt-like fixing member that circulates in contact with a rotating or rotating pressure member. An even number of heating elements are arranged, formed on one end of the heating member in the circumferential direction of the fixing member, a heating member that contacts the inner peripheral surface of the fixing member and heats the fixing member, An electrode portion for supplying power independently of at least a part of each of the heating elements, or at least a part of the heating elements, and one end portion of the heating member in the circumferential direction of the fixing member are formed. A grounding portion for grounding independently or at least partially in common with respect to the half, and formed at the other end portion of the heating member in the circumferential direction of the fixing member, from the electrode portion to the grounding portion I will energize And a connection portion for electrically connecting half of the heating elements and the remaining half of the heating elements respectively, and provided on the inner peripheral surface side of the fixing member, and presses the fixing member against the pressure member. And a pressing member to which one end of the heating member is attached.

  The fixing device according to claim 2 is the fixing device according to claim 1, wherein the heating element is disposed obliquely with respect to a circumferential direction of the fixing member and the half of the heating elements. And the other half of the heating elements are connected in series.

  The fixing device according to claim 3 is the fixing device according to claim 2, wherein in the half and the remaining half of the heating elements, the lengths of the heating elements adjacent to each other in the direction of the rotation axis are respectively. The lengths are different from each other.

  A fixing device according to a fourth aspect is the fixing device according to any one of the first to third aspects, wherein the heating member or the fixing member is disposed on an inner peripheral surface of the fixing member. The heating member is biased in the direction in which the heating member comes into contact.

  The fixing device according to claim 5 is the fixing device according to any one of claims 1 to 4, wherein the heating member is disposed between the pressing member and the fixing member. Has been.

  A fixing device according to a sixth aspect is the fixing device according to the fifth aspect, wherein one end of the heating member is provided upstream of the pressing member in the conveyance direction of the recording medium.

  The fixing device according to claim 7 is the fixing device according to claim 5, wherein one end portion of the heating member is provided on the downstream side of the pressing member in the conveyance direction of the recording medium, and the heating member The other end portion of the fixing member is folded back toward the rotation center side of the fixing member.

  An image forming apparatus according to an eighth aspect of the present invention includes an image forming unit that forms a toner image on a recording medium, and the toner image formed on the recording medium is fixed to the recording medium. And a fixing device according to claim 7.

  According to the first aspect of the present invention, the fixing device is compared with the configuration in which the electrode portion is formed on one end side in the rotation axis direction of the fixing member in the sheet-like heating member that heats the endless belt-shaped fixing member that circulates. The device itself can be downsized.

  According to the second aspect of the present invention, compared to the configuration in which the heating element is disposed along the circumferential direction of the fixing member, a portion that is not heated is not formed in the rotation axis direction of the fixing member.

  According to the third aspect of the present invention, the heat generation amount of the heating member can be adjusted as compared with the configuration in which the length of the fixing member in the rotation axis direction is the same in each heating element.

  According to the invention of claim 4, the heating member or the fixing member is more efficient than the configuration in which the heating member or the fixing member is not urged by the urging means in the direction in which the heating member contacts the inner peripheral surface of the fixing member. Can be heated.

  According to the fifth aspect of the present invention, compared to a configuration in which the heating member is not disposed between the pressing member and the fixing member, the portion of the fixing member where the recording medium is conveyed can be efficiently heated. .

  According to the invention which concerns on Claim 6, compared with the structure by which the one end part of a heating member is provided in the conveyance direction of the recording medium in a press member, it is easy to fix a heating member to a press member.

  According to the seventh aspect of the present invention, the heating member is brought into close contact with the inner peripheral surface of the fixing member as compared with the configuration in which the one end of the heating member is provided on the upstream side in the conveyance direction of the recording medium in the pressing member. Can do.

  According to the eighth aspect of the present invention, the image forming apparatus main body can be downsized as compared with a configuration that does not include a fixing device that can downsize the apparatus itself.

1 is a schematic configuration diagram illustrating an image forming apparatus according to an exemplary embodiment. 1 is a schematic cross-sectional view illustrating a fixing device according to a first embodiment. FIG. 3 is a schematic cross-sectional view illustrating a heating member of the fixing device according to the first embodiment. FIG. 3 is a schematic perspective view illustrating a heating member of the fixing device according to the first embodiment. FIG. 3 is a schematic plan view illustrating a configuration of a heating member of the fixing device according to the first embodiment. FIG. 3 is a schematic cross-sectional view illustrating a biasing unit for a heating member of the fixing device according to the first embodiment. FIG. 6 is a schematic cross-sectional view illustrating a configuration on a fixing member side of a fixing device according to a second embodiment. FIG. 6 is a schematic cross-sectional view illustrating a configuration on a fixing member side of a fixing device according to a second embodiment. FIG. 10 is a schematic cross-sectional view illustrating a configuration of a fixing member side of a fixing device according to a third embodiment.

  Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings. For convenience of explanation, an arrow UP appropriately shown in each figure is an upward direction of the image forming apparatus 10, and an arrow RH is a right direction of the image forming apparatus 10. Further, the front side of the drawing in FIG. 1 is the front direction of the image forming apparatus 10. Further, the conveyance direction of the recording paper P as an example of the recording medium may be simply referred to as “conveyance direction”, and the upstream side and the downstream side in the conveyance direction may be simply referred to as “upstream side” and “downstream side”, respectively. is there.

  As shown in FIG. 1, the image forming apparatus 10 is an example of an image forming unit that outputs an image of each color of yellow (Y), magenta (M), cyan (C), and black (K) in the apparatus main body 12. As electrophotographic image forming units 20Y, 20M, 20C, and 20K. In the following description, Y, M, C, and K alphabets are omitted as appropriate in the following description without distinguishing between yellow (Y), magenta (M), cyan (C), and black (K). .

  Each image forming unit 20 is provided side by side in the left-right direction, and has a photoconductive drum 22 that functions as an image holding member by forming an electrostatic latent image on the surface. Around the photosensitive drum 22, toner is transferred to an electrostatic latent image formed on the photosensitive drum 22 and a charging device 24 that charges the surface of the photosensitive drum 22 in order from the upstream side in the rotation direction. A developing device 26 that forms a toner image and a cleaning device 28 that removes the toner remaining on the photosensitive drum 22 after the toner image is transferred to an intermediate transfer belt 40 described later are disposed.

  An exposure device 30 is provided below each image forming unit 20. The exposure device 30 irradiates the surface of each photosensitive drum 22 with laser light based on the image signal, whereby an electrostatic latent image is formed on the surface of each charged photosensitive drum 22. ing. An intermediate transfer belt 40 is provided above each image forming unit 20.

  The intermediate transfer belt 40 has an endless shape, a drive roll 32 that is rotationally driven, an adjustment roll 34 that adjusts the deviation of the intermediate transfer belt 40 in the width direction (the rotational axis direction of the drive roll 32), and 2 The support rolls 36 and 38 are stretched. The intermediate transfer belt 40 is driven to rotate in the direction indicated by the arrow A when the drive roll 32 is driven to rotate.

  Further, a primary transfer roll 42 for primary transfer of the toner image onto the intermediate transfer belt 40 is provided at a position facing each photoconductor drum 22 in the vertical direction across the intermediate transfer belt 40. Then, at a position facing the drive roll 32 in the left-right direction with the intermediate transfer belt 40 interposed therebetween, a secondary image for secondary transfer of the toner image primary (multiple) transferred onto the intermediate transfer belt 40 onto the recording paper P is provided. A transfer roll 44 is provided.

  Note that the secondary transfer roll 44 is always in contact with the intermediate transfer belt 40 and is configured to be driven and rotated by the circumferential drive of the intermediate transfer belt 40. The position where the peripheral surface of the secondary transfer roll 44 contacts the peripheral surface of the intermediate transfer belt 40 is a secondary transfer position T.

  In addition, on the lower side of the exposure device 30, a paper storage unit 14 that stores the recording paper P is provided. A plurality of the illustrated paper storage sections 14 are provided so that recording papers P of different sizes can be stored respectively. On the downstream side of the paper storage unit 14, a delivery roll 16 that sends the recording paper P to the transport path H is provided, and a plurality of transport rolls 18 are arranged in the transport path H to the secondary transfer roll 44. Yes.

  On the downstream side of the secondary transfer position T, a fixing device 50 is provided that heats and pressurizes the toner image transferred onto the recording paper P and fixes it on the recording paper P. The fixing device 50 will be described in detail later. A discharge roll 46 for discharging the recording paper P on which the toner image is fixed to a paper discharge portion 48 formed on the upper portion of the apparatus main body 12 is provided in the transport path H on the downstream side of the fixing device 50. .

  Here, an image forming process performed by the image forming apparatus 10 will be briefly described.

  First, gradation data of each color is sequentially output from the image processing unit (not shown) to the exposure device 30, and each laser beam emitted from the exposure device 30 according to the gradation data of each color is charged by the charging device 24. The surface of the photosensitive drum 22 is scanned and exposed. Thereby, an electrostatic latent image is formed on the surface of each photosensitive drum 22.

  The electrostatic latent image formed on each photosensitive drum 22 is visualized as a toner image of each color of yellow (Y), magenta (M), cyan (C), and black (K) by each developing device 26. The Then, yellow (Y), magenta (M), cyan (C), black formed on the photosensitive drum 22 by the primary transfer rolls 42 disposed above the image forming units 20Y, 20M, 20C, and 20K. The toner images of the respective colors (K) are primary-transferred multiple times on the rotating intermediate transfer belt 40.

  On the other hand, the recording paper P is transported from the paper storage unit 14 to the transport path H by the delivery roll 16 and transported to the secondary transfer position T by the transport roll 18 at a predetermined transfer timing. Then, the toner images of the respective colors that have been primary-transferred in a multiple manner onto the rotating intermediate transfer belt 40 are secondarily transferred onto the recording paper P at the secondary transfer position T.

  The recording paper P to which the toner image has been transferred is conveyed to the fixing device 50, and the toner image transferred to the recording paper P is fixed to the recording paper P. Then, the recording paper P on which the toner image is fixed is discharged by a discharge roll 46 to a paper discharge unit 48 formed on the upper part of the apparatus main body 12.

<First Embodiment>
Next, the fixing device 50 according to the first embodiment will be described in detail.

  As shown in FIG. 2, the fixing device 50 includes a fixing member 52 that is formed in an endless belt shape and circulates, and a roll-shaped pressure member 54 that is disposed so as to come into contact with the outer peripheral surface of the fixing member 52. A pressing member 56 that is disposed on the inner peripheral surface side of the fixing member 52 so as to face the pressing member 54 and sandwiches the fixing member 52 between the pressing member 54 and the pressing member 54 is opposite to the pressing member 54. And a sheet-like heating member 60 that heats the fixing member 52 and is arranged so as to be in contact with the inner peripheral surface of the fixing member 52.

  The fixing member 52 is formed by forming a film-like member having a base layer made of a heat-resistant resin such as polyimide and a surface layer made of a fluororesin laminated on the base layer into an endless belt shape with the surface layer facing outside. Has been. The base layer has a thickness of 80 μm, for example, and the surface layer has a thickness of 30 μm, for example. The fixing member 52 is configured to rotate (followed rotation) when the pressure member 54 is rotationally driven.

  Further, the fixing member 52 has a portion sandwiched between the pressing member 54 and the pressing member 56 as a contact portion 52A, and the contact portion 52A can be flexibly deformed. When the fixing member 52 is supported in a state where no external force is applied, the fixing member 52 has a cylindrical shape having a substantially circular cross section due to the rigidity of the film-like member, and the outer diameter at this time is, for example, 30 mm. Yes. The width of the fixing member 52 (the length in the rotation axis direction extending in the front-rear direction) is larger than the width of the recording paper P, for example, 320 mm.

  The pressing member 54 is configured by forming an elastic layer 54B on the outer peripheral surface of a metal core 54A and laminating a surface layer 54C on the outer peripheral surface of the elastic layer 54B. The elastic layer 54B is, for example, a silicon sponge layer having a thickness of 5 mm, and the surface layer 54C is, for example, a fluororesin layer having a thickness of 30 μm. The outer diameter of the pressure member 54 is, for example, 28 mm.

  The pressing member 56 includes a pressing pad 57 that presses the inner peripheral surface of the fixing member 52 and a support portion 58 that supports the pressing pad 57. The pressing pad 57 is configured to continuously contact the contact portion 52A of the fixing member 52 in the entire width direction (rotational axis direction of the fixing member 52), and is elastically deformed to contact the fixing member 52. The portion 52 </ b> A is pressed against the pressure member 54. The pressing pad 57 is made of an elastic material having heat resistance such as silicone rubber.

  The support portion 58 is formed in a square cylindrical shape by combining two metal plates bent into a substantially “L” cross section, and is inserted into the cylindrical fixing member 52. The pressing pad 57 is supported in the direction of the rotation axis. The support portion 58 is configured to press the pressing pad 57 against the pressing member 54 side by applying a pressing force to both ends of the fixing member 52 in the rotation axis direction. In addition, the force which the support part 58 presses the press pad 57 to the pressurization member 54 side is 30 kg, for example.

  The heating member 60 is an elastically deformable sheet-like member formed with the rotation axis direction of the fixing member 52 as the longitudinal direction, and as described above, the inner periphery of the fixing member 52 on the side opposite to the pressure member 54. Arranged on the surface. The heating member 60 is fixedly supported by a support portion 58 of the pressing member 56 at an end portion (one end portion) located on the downstream side in the conveyance direction of the recording paper P. In the following, the end portion is referred to as “fixed end portion 60B”.

  On the other hand, the end 60A (the other end) of the heating member 60 located on the upstream side in the conveyance direction of the recording paper P is a free end, and the heating member 60 in the vicinity of the end 60A rotates the fixing member 52. It is folded back toward the center. Thereby, the bending rigidity in the rotation axis direction of the fixing member 52 in the vicinity of the end edge 60A is increased.

  As shown in FIG. 5, the sheet main body 62 of the heating member 60 that contacts the inner peripheral surface of the fixing member 52 is formed of a stainless steel plate having a thickness of 50 μm, for example. Accordingly, the bending rigidity of the heating member 60 is ensured, and when the heating member 60 undergoes bending deformation, an elastic repulsive force is generated on the heating member 60.

  That is, as shown in FIGS. 3 and 4, when the shape of the heating member 60 is not constrained by the fixing member 52, the heating member 60 has a shape protruding outward from the fixing member 52, and is mounted inside the fixing member 52. When this is done, it is elastically deformed and its shape is constrained by the fixing member 52 as shown by the one-dot chain line in FIG. That is, the heating member 60 is configured to be pressed against the inner peripheral surface of the fixing member 52 by the elastic repulsive force at this time and to be in a state of contacting in the circumferential direction.

  Since the heating member 60 is rubbed against the inner peripheral surface of the fixing member 52 as the fixing member 52 circulates, a frictional force acts on the heating member 60. Further, since the pressing pad 57 is also pressed against the inner peripheral surface of the fixing member 52, a frictional force acts between the pressing pad 57 and the fixing member 52.

  However, the total of the frictional force between the fixing member 52 and the heating member 60 and the frictional force between the fixing member 52 and the pressing pad 57 is due to the fact that lubricating oil is applied to the inner peripheral surface of the fixing member 52. The frictional force on the contact portion 52A of the fixing member 52 rotating around the pressure member 54 that is driven to rotate is smaller.

  An insulating layer (not shown) made of a heat-resistant resin is formed on the inner surface of the sheet main body 62 of the heating member 60 (the surface not in contact with the inner peripheral surface of the fixing member 52), and a thin sheet (foil) is formed thereon. A heating member 60 is configured by arranging an even number of heat generating elements 64 in the width direction (the rotation axis direction of the fixing member 52). The insulating layer is made of a heat-resistant resin having a thickness of about 25 μm, for example, polyimide, and electrically insulates between the heating element 64 and the sheet body 62 laminated on the insulating layer. It has become.

  The heating elements 64 are divided and arranged in an even number in the rotation axis direction of the fixing member 52 so as to face the toner image formable area on the recording paper P, and are arranged obliquely with respect to the transport direction. (See FIG. 5). That is, the one end side and the other end side in the circumferential direction of the adjacent heating elements 64 are arranged so as to overlap each other in the width direction (the rotation axis direction of the fixing member 52). The heating element 64 is provided except for the peripheral edge of the heating member 60 and is covered and protected by a coating layer (not shown) made of a heat resistant resin.

  Each heating element 64 is made of, for example, a stainless steel foil having a thickness of about 30 μm, and is formed in a meander shape and a rectangular shape, for example, in order to reduce the heat capacity and increase the electric resistance. Therefore, each heating element 64 generates heat rapidly when energized. In FIG. 5, each heating element 64 is shown as a rectangular shape for the sake of simplicity.

  The sheet main body 62 on the edge 60 </ b> A side that is the free end of the heating member 60 includes two sheets 1 from the inside to the outside in the width direction of the even number of heating elements 64 (rotational axis direction of the fixing member 52). Connection portions 67 that are electrically connected in series as a set are formed by patterning by a method such as etching a copper foil.

  On the other hand, the sheet main body 62 on the fixed end portion 60B side of the heating member 60 has an electrode portion 66 for supplying power to half of the even number of heating elements 64 on one side in the width direction by a method such as etching a copper foil. It is formed by patterning. The remaining half of the even number of heating elements 64 on the other side in the width direction is formed with a common ground portion 68 patterned by a method such as etching a copper foil.

  Further, the fixed end portion 60B of the heating member 60 is attached to the support portion 58 by screwing or the like. Thereby, each electrode part 66 and the grounding part 68 are electrically wired, and from each electrode part 66 to the half of each heating element 64, each connection part 67, the remaining half of each heating element 64, and the grounding part 68 are electrically connected. Are connected in series.

  That is, the power is supplied to each electrode portion 66 so that the ground portion 68 is energized, and the even number of heating elements 64 are heated. Further, the range of the heat generating body 64 that generates heat is determined according to the size of the recording paper P sent between the contact portion 52A of the fixing member 52 and the pressure member 54, and is energized.

  That is, since the recording paper P is conveyed through the central portion in the rotation axis direction of the fixing member 52, the electrode portions 66 to be fed are sequentially selected from the inside and are heated, thereby corresponding to the size of the recording paper P. It is possible. That is, since it is not necessary to supply power to the heating element 64 through which the recording paper P does not pass, the power can be saved.

  In addition, in the half of the even number of heating elements 64 on one side in the width direction and the remaining half on the other side in the width direction, the lengths of the adjacent heating elements 64 in the width direction (rotation axis direction of the fixing member 52) are different from each other. It may be a length. For example, the configuration in which the length of each heating element 64 arranged on the outer side in the width direction is sequentially narrower than the size of each heating element 64 arranged on the inner side in the width direction. May be.

  Moreover, the electrode part 66 is not limited to the structure provided independently in the half of the even number of heating elements 64 on one side in the width direction, and at least a part of the electrode part 66 is provided in common. May be. Furthermore, the grounding portion 68 is not limited to a configuration in which the other half of the even number of heating elements 64 on the other side in the width direction is provided in common, and is configured to be provided independently. Alternatively, only a part may be provided in common.

  Further, the heating element 64 is not limited to the above-described stainless steel, and may be a carbon nanotube, graphene, carbon black, or the like. In particular, carbon nanotubes are highly flexible and have the advantage that metal fatigue does not occur compared to stainless steel. The carbon nanotube heating element 64 is obtained by applying a carbon nanotube dispersion liquid in which carbon nanotube powder is dispersed in water or an organic solvent onto a heat-resistant base material such as polyimide and heat-treating it. Composed.

  Further, since the length of the heating element 64 in the circumferential direction (the circumferential direction of the fixing member 52) is determined, the electrical resistance of the heating element 64 is appropriately set to the length in the width direction (the rotation axis direction of the fixing member 52). It is adjusted by setting. In the case of the carbon nanotube heating element 64, the electrical resistance of each heating element 64 is adjusted by appropriately changing the concentration of the carbon nanotube dispersion and the number of coatings.

  Further, by adjusting the thickness of the sheet main body 62, the elastic repulsive force in the heating member 60, that is, the contact pressure with the fixing member 52 is adjusted. The contact pressure is adjusted by the biasing means 70 shown in FIG. May be adjusted (increased). More specifically, first, the heating member 60 in this case has a circumferential length shorter than that shown in FIG. Specifically, the heating member 60 is arranged in a substantially half on the downstream side in the conveyance direction of the recording paper P in the fixing member 52 and has a length that is not arranged in a substantial half on the upstream side in the conveyance direction.

  One or more urging means 70 are provided in the direction of the rotation axis of the fixing member 52. The urging means 70 includes a support column 72 provided on a side surface facing the right side of the support portion 58 and one end portion 74A supported in the vicinity of the tip end portion 72A of the support column 72. 60A includes a substantially “L” -shaped arm member 74 attached by screwing or the like, and a tension coil spring 76 that connects the distal end portion 72A of the support column 72 and the other end portion 74B of the arm member 74. ing.

  The support column 72 extends rightward from the side surface of the support portion 58, and protrudes in the vicinity of the front end portion 72 </ b> A on the front surface (or the rear surface) of the support column 72 in the direction of the rotation axis of the fixing member 52. Two columnar protrusions 73 are formed side by side in the transport direction (vertical direction).

  The arm member 74 extends from the distal end portion 72A of the support column 72 to the upstream side in the transport direction, which is the side where the heating member 60 is not disposed, and the extending direction (longitudinal direction) of the arm member 74 is at one end portion 74A. A long hole portion 75 is formed. Then, two protrusions 73 are inserted into the long hole portion 75.

  Therefore, the edge 60 </ b> A of the heating member 60 attached to the other end 74 </ b> B of the arm member 74 is guided by the two protrusions 73 inserted into the long hole portion 75, and is heated by the biasing force of the tension coil spring 76. It is the structure pulled by the conveyance direction downstream side used as the side in which 60 is arrange | positioned.

  Thereby, the contact pressure with respect to the fixing member 52 of the heating member 60 is supplementarily increased (the heating member 60 is brought into close contact with the inner peripheral surface of the fixing member 52). Note that the contact pressure of the heating member 60 with respect to the fixing member 52 can be adjusted by adjusting the biasing force of the tension coil spring 76 (by replacing the tension coil spring 76 with a different spring constant).

  Next, the operation of the fixing device 50 according to the first embodiment configured as described above will be described in detail.

  The recording paper P onto which the toner image has been transferred at the secondary transfer position T is fed between the contact portion 52A of the fixing member 52 and the pressure member 54 that are in contact with each other while rotating, and the contact portion 52A of the fixing member 52 and The toner image is fixed on the recording paper P by being heated and pressurized by the pressure member 54.

  Here, as described above, each heating element 64 in the heating member 60 has a small thickness and a small heat capacity. Accordingly, the heating member 60 is heated quickly and efficiently uniformly by energization, and the fixing member 52 is rapidly shifted to a state where fixing is possible. Therefore, the power consumption during the standby time until the start of printing in the image forming apparatus 10 is reduced.

  Further, the electrode part 66 and the grounding part 68 for that purpose are wired by attaching the heating member 60 to the support part 58 only on the fixed end part 60B side of the heating member 60, and the electrode part 66 has an even number of sheets. Only half of the heating elements 64 are formed. Accordingly, the number of electrodes can be reduced and the size of the fixing device 50 itself can be reduced as compared with a configuration in which an electrode portion for each heating element is formed on one end side in the rotation axis direction of the fixing member 52 in the heating member 60. In particular, the size in the width direction (the rotation axis direction of the fixing member 52) is reduced. Therefore, the size in the front-rear direction of the apparatus main body 12 of the image forming apparatus 10 is also reduced.

  Further, as described above, each heating element 64 in the heating member 60 is disposed obliquely with respect to the circumferential direction of the fixing member 52 (one end side and the other end side in the circumferential direction of the adjacent heating elements 64 are respectively And the fixing member 52 overlaps in the rotation axis direction). Therefore, as compared with the configuration in which each heating element 64 is arranged along the circumferential direction of the fixing member 52, a portion that is not heated is not formed in the rotation axis direction of the fixing member 52.

  Further, in the half of the even number of heating elements 64 on one side in the width direction and the remaining half on the other side in the width direction, the lengths of the adjacent heating elements 64 in the width direction are different from each other (each heat generation). The length in the width direction of the body 64 is different from that in the width direction of the heating elements 64), and the length in the width direction. Since the electric resistance of each heating element 64 is adjusted as compared with a configuration in which the heating members 60 are the same, the heat generation amount of the heating member 60 is adjusted.

  The heating member 60 is constrained to a shape along the inner peripheral surface of the fixing member 52 and is in contact with the inner peripheral surface of the fixing member 52 that circulates. That is, the heating member 60 constrained in an elastically deformed state on the inner peripheral surface side of the fixing member 52 is pressed against the inner peripheral surface of the fixing member 52 by its elastic repulsive force. Therefore, the contact pressure in a wide range from the fixed end portion 60B side to the end edge 60A side of the heating member 60 is suppressed from becoming uneven in the rotation axis direction of the fixing member 52 (tension distortion is generated), and fixing is performed. The entire member 52 is efficiently and stably heated.

  Further, in the heating member 60 shown in FIG. 6, not only the elastic repulsion force of the sheet main body 62 but also the biasing force of the tension coil spring 76 in the vicinity of the edge 60A assists in the contact pressure with respect to the inner peripheral surface of the fixing member 52. Has been enhanced. Therefore, even if vibration is generated due to friction between the heating member 60 and the fixing member 52, occurrence of a portion (tension strain) that is not in contact with the fixing member 52 in the heating member 60 is reduced. , The occurrence of a part where the temperature rises partially is suppressed.

Second Embodiment
Next, the fixing device 50 according to the second embodiment will be described in detail. In addition, the same code | symbol is attached | subjected to the site | part equivalent to the said 1st Embodiment, and detailed description is abbreviate | omitted suitably.

  As shown in FIG. 7, in the fixing device 50 according to the second embodiment, the heating member 60 is disposed between the metal pressing member 88 and the fixing member 52. More specifically, the pressing member 88 is divided into a first pressing member 88A on the upstream side and a second pressing member 88B on the downstream side, which are made of metal having a substantially inverted “U” shape in cross section. They are connected by a support portion 78.

  In the contact portion 52A of the fixing member 52, a clearance S along the transport direction is formed between the first pressing member 88A and the second pressing member 88B, so that the contact portion 52A of the fixing member 52 can be flexibly deformed. It becomes the composition which becomes. The fixed end portion 60B of the heating member 60, that is, the electrode portion 66 and the grounding portion 68 are attached to the side surface facing the right side of the first pressing member 88A by screwing or the like.

  Thereby, each electrode part 66 and the grounding part 68 of the heating member 60 are electrically wired via the first pressing member 88 </ b> A and the support part 78. The heating member 60 is disposed between the first pressing member 88A and the second pressing member 88B and the fixing member 52 so as to extend from the upstream side to the downstream side.

  Further, the heating member 60 is pressed against the inner peripheral surface of the fixing member 52 near the entrance of the recording paper P on the side surface facing the left side of the first pressing member 88A (contact of the heating member 60 with the inner peripheral surface of the fixing member 52). A first urging portion 80 is disposed as an example of the urging means 70 (which supplementarily increases the pressure). The contact pressure between the heating member 60 and the fixing member 52 is increased near the entrance of the recording paper P, so that the recording paper P is efficiently heated from the vicinity of the entrance.

  The first urging portion 80 extends in the direction of the rotation axis of the fixing member 52 and has an urging portion main body 82 made of a heat-resistant resin whose arcuate curved surface contacts the heating member 60 and the urging portion main body 82 leftward. And a plurality of compression coil springs 84 biased toward the same. One end portion of each compression coil spring 84 is attached to the flat surface 82A of the biasing portion main body 82, and the other end portion is attached to the bottom surface 86A in the groove portion 86 formed in the first pressing member 88A. .

  Further, by pressing a part of the fixing member 52 opposite to the pressure member 54 from the inner peripheral surface side on the side surface 78A facing the right side of the support portion 78, the fixing member 52 with respect to the heating member 60. A second urging portion 90 as an example of an urging means 70 for assistingly increasing the contact pressure of the inner peripheral surface is disposed.

  The second urging unit 90 includes an urging unit main body 92 made of metal (or heat-resistant resin) that extends in the rotation axis direction of the fixing member 52 and has an arcuate curved surface that contacts the fixing member 52, and the urging unit main body 92. And a leaf spring 94 having a substantially “V” cross section for urging the spring toward the right. One end of the leaf spring 94 is attached to the flat surface 92 </ b> A of the urging portion main body 92, and the other end is attached to the side surface 78 </ b> A of the support portion 78.

  In the first urging portion 80 and the second urging portion 90 that press the fixing member 52 in the opposite directions from the inner peripheral surface side, the urging portion main body 92 of the second urging portion 90 is the first one. The biasing portion 80 is formed larger than the biasing portion main body 82. The urging force of the plate spring 94 of the second urging unit 90 is stronger than that of the compression coil spring 84 of the first urging unit 80.

  Thereby, the contact pressure at the contact portion 52A of the fixing member 52 with respect to the heating member 60 is further improved. The first urging unit 80 and the second urging unit 90 may be configured such that a plurality of urging unit main bodies 82 and 92 each having a hemispherical shape are provided in the rotation axis direction of the fixing member 52. . Further, the end edge 60A of the heating member 60 is not joined to the second pressing member 88B, and is a free end as in the first embodiment.

  Next, the operation of the fixing device 50 according to the second embodiment configured as described above will be described in detail. In addition, about the effect | action common to the said 1st Embodiment, it abbreviate | omits suitably.

  The heating member 60 in the second embodiment is disposed between the first pressing member 88 </ b> A and the second pressing member 88 </ b> B (pressing member 88) and the contact portion 52 </ b> A of the fixing member 52. Therefore, the contact portion of the fixing member 52 is compared with a configuration in which the heating member 60 is not disposed between the first pressing member 88A and the second pressing member 88B (pressing member 88) and the contact portion 52A of the fixing member 52. 52A is efficiently heated.

  Further, the heating member 60 in the second embodiment has its electrode portion 66 and grounding portion 68 (fixed end portion 60B) attached to the upstream side, that is, the first pressing member 88A. Therefore, the electrode portion 66 and the grounding portion 68 (fixed end portion) of the heating member 60 are compared with the configuration in which the electrode portion 66 and the grounding portion 68 (fixed end portion 60B) of the heating member 60 are attached to the downstream side, that is, the second pressing member 88B. 60B) is easily secured, and the electrode portion 66 and the grounding portion 68 (fixed end portion 60B) are easily fixed.

  Moreover, since the edge 60A of the heating member 60 is not joined to the second pressing member 88B, there is no possibility that the thermal expansion of the heating member 60 is hindered by the second pressing member 88B. In addition, the shape of the 2nd press member 88B and the shape of the support part 78 are not limited to the shape shown by FIG. 7, For example, you may be set as the shape shown by FIG.

  That is, as shown in FIG. 8, the second pressing member 88B may extend rightward and the upper side of the support portion 78 may be disposed above the second pressing member 88B. That is, the second pressing member 88B may be disposed inside the support portion 78, and the right side surface of the second pressing member 88B may be in contact with the inner surface of the support portion 78.

  According to this, since the position of the second pressing member 88B is more effectively restricted to the left side by the support portion 78, the contact portion of the fixing member 52 is compared with the second pressing member 88B shown in FIG. The contact pressure of the heating member 60 with respect to 52A is improved, and the contact portion 52A of the fixing member 52 is heated more efficiently.

<Third Embodiment>
Next, the fixing device 50 according to the third embodiment will be described in detail. In addition, the same code | symbol is attached | subjected to the site | part equivalent to the said 2nd Embodiment, and detailed description is abbreviate | omitted suitably.

  As shown in FIG. 9, in the fixing device 50 according to the third embodiment, the fixed end portion 60B of the heating member 60, that is, the electrode portion 66 and the grounding portion 68 are screwed to the upper surface of the second pressing member 88B. The heating member 60 is disposed so as to extend from the downstream side to the upstream side between the first pressing member 88 </ b> A and the second pressing member 88 </ b> B and the fixing member 52. An end edge 60 </ b> A that is a free end of the heating member 60 disposed on the upstream side is folded back toward the rotation center side of the fixing member 52.

  Next, the operation of the fixing device 50 according to the third embodiment configured as described above will be described in detail. In addition, about the effect | action common to the said 1st Embodiment and 2nd Embodiment, it abbreviate | omits suitably.

  In the heating member 60 in the third embodiment, the electrode portion 66 and the grounding portion 68 (fixed end portion 60B) are attached to the downstream side, that is, the second pressing member 88B. Accordingly, a compression force acts on the heating member 60 toward the fixed end 60 </ b> B along the peripheral surface of the fixing member 52 due to friction between the fixing member 52 and the heating member 60.

  Therefore, the heating member 60 has an inner portion of the fixing member 52 as compared with the configuration in which the electrode portion 66 and the ground portion 68 (fixed end portion 60B) of the heating member 60 are attached to the upstream side, that is, the first pressing member 88A. It is easy to be in close contact with the peripheral surface. Note that the frictional force between the fixing member 52 and the heating member 60 is appropriately set (smaller) so that the heating member 60 does not buckle due to the compressive force or does not cause a large deformation near the fixed end 60B. ing.

  Further, the edge 60 </ b> A of the heating member 60 disposed on the upstream side is folded back toward the rotation center side of the fixing member 52. Therefore, even if the edge 60A of the heating member 60 extends in the direction opposite to the circumferential direction of the fixing member 52, the lubricating oil applied to the inner peripheral surface of the fixing member 52 is scraped off by the edge 60A. It is not.

  The fixing device 50 according to the present embodiment has been described with reference to the drawings. However, the fixing device 50 according to the present embodiment is not limited to the illustrated one and does not depart from the gist of the present invention. The design can be changed as appropriate. For example, the pressure member 54 is not limited to a configuration formed in a roll shape, and may be configured to be formed in an endless belt shape and driven in a circular manner like the fixing member 52.

  The heating member 60 has a spiral shape in which the distance from the center point increases in proportion to the angle when the heating member 60 is not restrained by the fixing member 52, but the sectional shape when the heating member 60 is not restrained. However, the shape of the fixing member 52 is not limited to this, and may be any shape that can contact the fixing member 52 in a wide range in the circumferential direction.

  Further, the number of the heating elements 64 may be an even number, and is not limited to the eight illustrated. Furthermore, the heating member 60 may be formed in a flat plate shape and applied to a droplet discharge device (not shown). In other words, the heating member 60 may be disposed on the lower surface side of the paper conveyance path facing the liquid droplet ejection head so that moisture in the ink ejected from the liquid droplet ejection head onto the recording paper P can be quickly evaporated.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 20 Image forming unit (an example of image forming part)
DESCRIPTION OF SYMBOLS 50 Fixing device 52 Fixing member 54 Pressure member 56 Pressing member 60 Heating member 64 Heating element 66 Electrode part 67 Connection part 68 Grounding part 70 Energizing means 80 1st energizing part (an example of an energizing means)
90 Second urging unit (an example of urging means)
P Recording paper (an example of a recording medium)

Claims (8)

An even number of sheet-like heating elements are arranged in the rotation axis direction of the endless belt-shaped fixing member that circulates in contact with the rotating or rotating pressure member, and contacts the inner peripheral surface of the fixing member. A heating member for heating the fixing member;
An electrode portion that is formed at one end portion of the heating member in the circumferential direction of the fixing member, and that feeds power independently or at least partially in common with half of the heating elements;
A grounding portion that is formed at one end of the heating member in the circumferential direction of the fixing member and is grounded independently or at least partially in common with the other half of the heating element;
The other half of the heating element and the other half of the heating element are electrically connected to the other end portion of the heating member in the circumferential direction of the fixing member so as to energize from the electrode portion to the ground portion. A connection to be connected;
A pressing member that is provided on the inner peripheral surface side of the fixing member, presses the fixing member against the pressure member, and is attached with one end of the heating member;
A fixing device provided with   2. The fixing device according to claim 1, wherein the heating elements are arranged obliquely with respect to a circumferential direction of the fixing member, and the half of the heating elements and the remaining half of the heating elements are connected in series. .   3. The fixing device according to claim 2, wherein in the half and the remaining half of the heating elements, the heating elements adjacent to each other have different lengths in the rotation axis direction.   4. The fixing according to claim 1, wherein the heating member or the fixing member is biased by a biasing unit in a direction in which the heating member comes into contact with an inner peripheral surface of the fixing member. apparatus.   The fixing device according to claim 1, wherein the heating member is disposed between the pressing member and the fixing member.   The fixing device according to claim 5, wherein one end portion of the heating member is provided on the upstream side of the pressing member in the conveyance direction of the recording medium.   6. The heating member according to claim 5, wherein one end portion of the heating member is provided on a downstream side of the pressing member in a conveyance direction of the recording medium, and the other end portion of the heating member is folded toward the rotation center side of the fixing member. Fixing device. An image forming unit for forming a toner image on a recording medium;
The fixing device according to claim 1, wherein the toner image formed on the recording medium is fixed to the recording medium.
An image forming apparatus.