Fixing device

Abstract

The invention relates to a fixing device. The fixing device includes: a heating unit including a belt and a heater configured to heat the belt; a pressure roller configured to form a nip together with the heater with the belt therebetween; a conductive pressure spring configured to urge the pressure arm so as to press the heating unit against the pressure roller; a conductive bearing that supports a rotating shaft of the pressure roller; a frame made of resin and supporting the bearing; a conductive brush member provided in contact with the belt; and a first conductor portion provided to be in contact with both the brush member and the pressure spring.

Description

Technical Field

[0001] This disclosure relates to an electrophotographic image forming apparatus. Background Technology

[0002] The fixing apparatus discussed in Japanese Patent Publication No. 2024-31208 includes a heating unit and a pressure roller. The heating unit includes a heater configured to heat the inner surface of a heating belt. The pressure roller is configured to form a pressing section together with the heater, wherein a belt is located between the pressure roller and the heater. The fixing apparatus is configured to fix toner onto recording material. Summary of the Invention

[0003] This disclosure provides a novel fixing device that overcomes the shortcomings of the prior art.

[0004] One aspect of this disclosure provides

[0005] A fixing device configured to be attached to an image forming apparatus, the fixing device comprising:

[0006] A heating unit, the heating unit comprising a belt and a heater, the heater being configured to heat the belt;

[0007] A pressure roller, which is configured to form a pressing portion together with the belt;

[0008] A pressure arm, configured to press the heating unit relative to the pressure roller;

[0009] A conductive pressure spring is configured to push the pressure arm to press the heating unit relative to the pressure roller;

[0010] A conductive bearing, configured to support the rotating shaft of the pressure roller;

[0011] A frame made of resin that supports the bearing;

[0012] The conductive brush component is disposed in contact with the ground.

[0013] A first conductor portion is configured to contact the brush component and the pressure spring, such that the brush component and the pressure spring are electrically connected to each other;

[0014] A second conductor portion, configured to contact the pressure spring and the main conductor portion of the image forming apparatus, such that the pressure spring and the main conductor portion are electrically connected to each other; and

[0015] A third conductor portion is configured to contact the first conductor portion and the bearing, such that the rotating shaft and the main conductor portion are electrically connected to each other.

[0016] The features of this disclosure will become clear from the following description of embodiments with reference to the accompanying drawings. The following description of embodiments is by way of example. Attached Figure Description

[0017] Figure 1A This is a perspective view of the fixing device according to the first embodiment.

[0018] Figure 1B This is another perspective view of the fixing device according to the first embodiment.

[0019] Figure 2 This is a cross-sectional view of an image forming apparatus to which the fixing device according to the first embodiment is applied.

[0020] Figure 3 This is a cross-sectional view of the fixing device according to the first embodiment.

[0021] Figure 4 This is another cross-sectional view of the fixing device according to the first embodiment.

[0022] Figure 5 This is an exploded perspective view of the fixing device according to the first embodiment.

[0023] Figure 6A This is a perspective view of the fixing device according to the first embodiment.

[0024] Figure 6B This is another perspective view of the fixing device according to the first embodiment.

[0025] Figure 7 This is a top view of the fixing device according to the first embodiment.

[0026] Figure 8 This is a perspective view of the fixing device according to the first embodiment.

[0027] Figure 9 This is a cross-sectional view of the fixing device according to the first embodiment.

[0028] Figure 10A This is a front view of the contact spring according to the first embodiment.

[0029] Figure 10B This is a plan view of the contact spring according to the first embodiment.

[0030] Figure 11A This is a front view of the fixing device according to the first embodiment.

[0031] Figure 11B It is the fixing device according to the first embodiment. Figure 11A The cross-sectional view of the XIB-XIB line is given in the figure.

[0032] Figure 11C It is the fixing device according to the first embodiment. Figure 11A The cross-sectional view of the XIC-XIC line is given in the figure.

[0033] Figure 11D It is the fixing device according to the first embodiment. Figure 11A The cross-sectional view of the XID-XID line is given in the figure.

[0034] Figure 12A This is a cross-sectional view of the fixing device according to the first embodiment.

[0035] Figure 12B This is another cross-sectional view of the fixing device according to the first embodiment.

[0036] Figure 13 This is an exploded perspective view of the fixing device according to the first embodiment.

[0037] Figure 14 This is a plan view of the fixing device according to the first embodiment.

[0038] Figure 15 This is another plan view of the fixing device according to the first embodiment.

[0039] Figure 16 This is another plan view of the fixing device according to the first embodiment.

[0040] Figure 17 This is another plan view of the fixing device according to the first embodiment.

[0041] Figure 18 This is a perspective view of the fixing device according to the first embodiment.

[0042] Figure 19 This is another perspective view of the fixing device according to the first embodiment.

[0043] Figure 20 This is a plan view of the fixing device according to the second embodiment.

[0044] Figure 21 This is another plan view of the fixing device according to the second embodiment.

[0045] Figure 22 This is another plan view of the fixing device according to the second embodiment.

[0046] Figure 23 This is a plan view of the fixing device according to the third embodiment.

[0047] Figure 24A This is a cross-sectional view of a portion of the fixing device according to the fourth embodiment.

[0048] Figure 24B This is a plan view of a portion of the fixing device according to the fourth embodiment. Detailed Implementation

[0049] Embodiments of this disclosure will now be described with reference to the accompanying drawings. The dimensions, materials, shapes, relative positions, and other factors of the elements described in the following embodiments may be appropriately varied depending on the configuration and / or conditions employed in the apparatus to which this disclosure is applied. Therefore, unless otherwise specified, the scope of this disclosure is not limited to the following embodiments.

[0050] (First Embodiment)

[0051] Figure 2 This is a cross-sectional view of the electrophotographic image forming apparatus 1 to which the fixing device 6 according to the first embodiment is applied. In the following description, as... Figure 2 As shown in the diagram, when the image forming apparatus 1 is mounted horizontally, the vertical direction is the Z-direction, as follows: Figures 2 to 6B , Figures 8 to 9 , Figure 11A , Figures 12A to 22 And as shown in Figure 24. The Y direction intersects the Z direction and is parallel to the rotation axis direction of the pressure arm 652 described below. The X direction intersects both the Z and Y directions. The X direction is parallel to the direction in which the heating unit 61, described below, conveys the recording material (also called the sheet S) located at the pressing section np1. The X and Y directions may each correspond to a horizontal direction. The X, Y, and Z directions may be orthogonal to each other. Some figures have arrows indicating the X, Y, and Z directions, with one side of each arrow indicating a corresponding one of +X, +Y, and +Z, and the other side indicating a corresponding one of -X, -Y, and -Z. In the following description, the direction in which the recording material is conveyed at the pressing section np1 is referred to as the recording material conveying direction (+X direction). The +X direction coincides with the direction in which the fixing device 6 is attached to the device body 2, and may also be referred to as the "attachment direction" in the following description. The rotation axis direction of the pressure arm 652 described below is also referred to as the axial direction. Regarding the axial direction, the direction from the heating unit 61 toward the electrical contact 668b1 is referred to as the first axial direction (+Y direction). Regarding the axial direction, the direction opposite to the first axial direction is called the second axial direction (-Y direction). The Y direction is consistent with the direction of the long side of the heating unit 61. The Y direction is also consistent with the direction of the generatrix of the belt 614. Regarding the direction of the long side of the heating unit 61, the direction from the contact spring 668 toward the center of the long side of the heating unit 61 is called the first direction (-Y direction).

[0052] (Image forming apparatus)

[0053] Now refer to Figure 2 The configuration of the image forming apparatus 1 is described. The image forming apparatus 1 includes an apparatus body 2, a processing cartridge 10, and a fixing device 6. The processing cartridge 10 is detachably attached to the apparatus body 2. The fixing device 6 is detachably attached to the apparatus body 2. The fixing device 6 is included in the apparatus body 2. The fixing device 6 may be configured to be non-detachable from the apparatus body 2.

[0054] The main body 2 of the device includes a sheet feed tray 3, a sheet feeder 4, a transport path P, a transfer roller 51, a sheet ejector 7, a sheet receiving tray 8, a laser scanner 9, and a door 21. The processing cartridge 10 includes a photosensitive drum 11 and a developing roller 12. The developing roller 12 acts as a developer carrier. The developer (also called toner) is contained inside the processing cartridge 10. The door 21 is supported in a manner rotatable about a rotation axis 21a and can move between a closed position with the opening 2a closed and an open position with the opening 2a open. When the door 21 is in the open position with the opening 2a open, the processing cartridge 10 can be attached to or detached from the main body 2 of the device through the opening 2a.

[0055] The sheet feeder 4 includes a sheet feed roller 41, a separation roller 42, a separation pad 42a, and a transport roller pair 43. In response to a printing start signal, the sheet S contained in the sheet feed tray 3 is conveyed by the sheet feeder 4 to the transport path P and transported to the transfer roller 51 via the alignment roller pair 44.

[0056] When the sheet S reaches a predetermined position, an image formation start signal is emitted, thereby initiating the image formation process. The photosensitive drum 11 is rotated by a drive source (e.g., a motor) and uniformly charged by a charger to have a predetermined potential. The laser scanner 9 exposes the charged surface of the photosensitive drum 11 with light generated based on image information, thereby forming an electrostatic latent image while removing the charge from the exposed portion. The toner contained in the processing cartridge 10 is carried by the developing roller 12 and supplied to the photosensitive drum 11 according to the electrostatic latent image, thereby developing the electrostatic latent image into a toner image and displaying it on the photosensitive drum 11.

[0057] The transfer roller 51 is positioned facing the photosensitive drum 11 included in the processing cartridge 10. When the sheet S, conveyed by the alignment roller pair 44, passes through the pressing section formed between the photosensitive drum 11 and the transfer roller 51, voltage is applied from the device body 2 to the transfer roller 51, thereby transferring the toner image on the photosensitive drum 11 as an unfixed image onto the sheet S. The sheet S with the transferred toner image is then conveyed to the fixing device 6, which includes a heating unit 61 and a rotary pressure member 62. The fixing device 6 is configured to fix toner (developer) onto recording material. When the sheet S passes through the pressing section np1 formed between the heating unit 61 and the rotary pressure member 62, the unfixed image on the sheet S is heated and pressurized, thereby fixing it onto the surface of the sheet S. The sheet S with the fixed toner image is conveyed by the sheet ejector 7 and ejected into the sheet receiving tray 8.

[0058] (Fixing equipment)

[0059] The composition of fixing device 6 will now be described. Figure 3 This is a cross-sectional view of fixing device 6. (For example...) Figure 3 As shown in the diagram, the heating unit 61 includes a heater 611, a retainer 612, a support 613, and a belt 614. The heater 611 is disposed inside the belt 614 and configured to heat the belt 614. The heater 611 extends along the generatrix direction (Y direction) of the belt 614 and has a flat plate shape. The heater 611 has a first surface 611a and a second surface 611b, the second surface 611b being located opposite the first surface 611a. The heater 611 is supported at the first surface 611a by the retainer 612.

[0060] The retainer 612 is made of a heat-resistant resin such as polyphenylene sulfide (PPS) or a liquid crystal polymer, and includes a guide surface 612a and a support wall 612b. The guide surface 612a guides the belt 614 while contacting the inner circumferential surface 614a of the belt 614. The support wall 612b has a support surface 612b1 on which the heater 611 is supported. The support surface 612b1 of the support wall 612b contacts the first surface 611a of the heater 611. A support member 613 supports the retainer 612 and is made of a sheet material with a higher stiffness than the retainer 612. For example, a steel sheet with a thickness of 1.6 mm is bent into a generally U-shape to obtain the support member 613.

[0061] The belt 614 is a heat-resistant and flexible annular belt. The belt 614 can be, for example, a metal sleeve made of stainless steel and coated with fluorocarbon resin, or a stacked structure of polyimide resin, silicone rubber, fluorocarbon resin, etc. The belt 614 surrounds the heater 611, the retainer 612, and the support 613, and rotates around them. The inner circumferential surface 614a of the belt 614 contacts the second surface 611b of the heater 611.

[0062] The rotary pressing member 62 (pressure roller) includes a shaft 62a made of metal and a roller 62b made of elastic material and covering the shaft 62a. The rotary pressing member 62 is pressed onto the heater 611, with a belt 614 located between them. The rotary pressing member 62 cooperates with the heater 611 to press the belt 614 between them, thereby forming a pressing portion np1 in which the sheet S will be pressed under heat and pressure. The rotary pressing member 62 (pressure roller) is configured to form the pressing portion np1 together with the heater 611, with the belt 614 between the rotary pressing member 62 and the heater 611. That is, the rotary pressing member 62 and the heater 611 cooperate to heat and pressurize the sheet S at the pressing portion np1.

[0063] The rotary pressure member 62 is configured to rotate by receiving a driving force transmitted from a drive source included in the image forming apparatus 1. As the rotary pressure member 62 rotates, the belt 614 rotates in a manner that follows the rotary pressure member 62. A sheet S with a toner image transferred onto it is conveyed between the rotary pressure member 62 and the heating belt 614, thereby heat-fixing the toner image.

[0064] See Figure 4 The framework structure of the fixing device 6 will be described. Figure 4 This is a cross-sectional view of the fixing device 6. The fixing device 6 includes an upper frame 64 and a lower frame 63. The upper frame 64 may also be referred to as the first frame, and the lower frame 63 may also be referred to as the second frame. The lower frame 63 supports the heating unit 61 and the rotating pressure member 62. The upper frame 64 (first frame) is located above the lower frame 63 (second frame) and covers the heating unit 61. Both the lower frame 63 and the upper frame 64 are formed as non-conductive molded members made of resin. The upper frame 64 includes an upper guide surface 64a located downstream of the heating unit 61 in the recording material transport direction (+X direction). The upper guide surface 64a guides the sheet S, which is transported along the recording material transport direction, at the surface (upper surface) of the sheet S facing the heating unit 61. The lower frame 63 includes a lower guide surface 63a located downstream of the heating unit 61 in the recording material transport direction. The lower guide surface 63a guides the lower surface of the sheet S, which is transported along the recording material transport direction.

[0065] See Figure 5The structure of the lower frame 63 supporting the rotating pressurization member 62 will be described. Figure 5 This is an exploded perspective view of the fixing device 6. The lower frame 63 includes guide rails 63b at both its first axial end and its second axial end. The guide rails 63b extend vertically and support the retainer 612 while allowing the retainer 612 to move vertically. The guide rails 63b are axially opposite each other. The guide rails 63b engage with grooves 617a1 and 617b1 provided in the respective transmission members 617a and 617b.

[0066] The fixing device 6 includes bearings 62c and 62d. The ends of shaft 62a located on the first axial side and the ends of shaft 62a located on the second axial side are supported by corresponding bearings 62c and 62d. Bearing 62c is positioned by fitting into a recess 63d1 provided in the lower frame 63. Similarly, bearing 62d is positioned by fitting into a recess 63d2 provided in the lower frame 63. Bearing 62c is conductive. In this configuration, bearings 62c and 62d have protrusions, while the lower frame 63 has recesses 63d1 and 63d2. The positions of the protrusions and recesses can be interchanged. Furthermore, the elements that fix bearings 62c and 62d to the lower frame 63 do not necessarily need to be protrusions and recesses.

[0067] (Pressure mechanism)

[0068] The configuration of the pressurizing mechanism 65 included in the fixing device 6 will now be described. Figure 11A This is a front view of the fixing device 6. Figures 11B to 11D Diagrammatic explanation from Figure 11A The corresponding cross section that was cut off.

[0069] like Figures 11A to 11D As shown in the diagram, the fixing device 6 includes a pressurizing mechanism 65, which is configured to press the heating unit 61 against the rotating pressurizing member 62. The pressurizing mechanism 65 is located at each of the two ends of the lower frame 63, on a first axial side and a second axial side. In other words, the pressurizing mechanism 65 is supported by the lower frame 63. The pressurizing mechanism 65 located at the end on the first axial side of the lower frame 63 has substantially the same configuration as the pressurizing mechanism 65 located at the end on the second axial side of the lower frame 63. The following description of the pressurizing mechanism 65 at the end on the first axial side also applies to the pressurizing mechanism 65 at the end on the second axial side; for the sake of brevity, redundant descriptions are incorporated herein by reference.

[0070] Each pressurizing mechanism 65 includes a transmission component 651, a pressurizing arm 652, and a pressurizing spring 653. The pressurizing arm 652 is supported by a lower frame 63. More specifically, the pressurizing arm 652 is supported by a support portion 64d of the lower frame 63 and is rotatable about the central axis X1 of the support portion 64d. The support portion 64d is a generally cylindrical protrusion.

[0071] The pressure arm 652 presses down on the transmission member 651 from above, causing the transmission member 651 to move downwards. Consequently, the transmission member 651 presses down on the support member 613. The transmission member 651 pressing on the support member 613 causes the support member 613 to move downwards. As the support member 613 moves downwards, the heating unit 61, including the support member 613, is pressed against the rotating pressure member 62. The pressure spring 653 is a conductive helical tension spring that pushes the pressure arm 652, causing the heating unit 61 to be pressed against the rotating pressure member 62. The pressure spring 653 engages with the lower frame 63 and the pressure arm 652. As the pressure spring 653 pushes the pressure arm 652, the pressure arm 652 causes the transmission member 651 to move downwards. That is, the pressure arm 652 presses the heating unit 61 against the rotating pressure member 62 (pressure roller).

[0072] (Pressure / Release Mechanism)

[0073] See Figure 12A and Figure 12B as well as Figure 13 The configuration of the pressurization / release mechanism 67 included in the fixing device 6 will be described. Figure 12A and Figure 12B This is a cross-sectional view of the fixing device 6. Figure 12A The diagram illustrates the pressurization state when the pressurization of the pressurization / release mechanism 67 is activated. Figure 12B The diagram illustrates the release state of the pressurization / release mechanism 67 when the pressurization is deactivated. Figure 13 This is an exploded perspective view of the fixing device 6, illustrating the upper frame 64, lower frame 63, and camshaft 671, but not some components such as the heating unit 61 and the rotary pressurizing member 62. The pressurization / release mechanism 67 is a pressing pressure application / relief mechanism configured to change the pressing pressure generated at the pressing portion np1 formed between the heating unit 61 and the rotary pressurizing member 62. The pressurization / release mechanism 67 includes a camshaft 671 and a cam 672.

[0074] See Figure 12A and Figure 12B The camshaft 671 is rotatable about axis X2. The camshaft 671 extends axially and is made of conductive metal. For example... Figure 13 As shown in the diagram, cam 672 is fixed to (supported on) the corresponding ends of camshaft 671 located on the first and second axial sides. Cam 672 is supported in such a way that it rotates together with camshaft 671. Cam 672 is disposed at the corresponding ends of lower frame 63 located on the first and second axial sides. Cam 672 disposed at the end of lower frame 63 on the first axial side and cam 672 disposed at the end of lower frame 63 on the second axial side have substantially the same configuration.

[0075] Each cam 672 presses against the thrust applied by the pressure spring 653 against the pressure arm 652. Therefore, the rotation of the cam 672 changes the pressing force applied by the pressure arm 652 to the rotating pressure member 62 of the heating unit 61. The cam 672 can... Figure 12A The pressurization position shown in the diagram and Figure 12B Rotate between the release positions shown in the diagram.

[0076] To release the pressure, the camshaft 671 is rotated, thereby rotating the cam 672. As the cam 672 rotates, the pressure arm 652, which is in contact with the cam 672, moves away from the transmission member 651 in a direction opposite to the direction in which the transmission member 651 presses against the support member 613.

[0077] Therefore, the force that presses the heating unit 61 against the rotating pressure member 62 is reduced.

[0078] See Figure 13 The structure supporting the camshaft 671 will be described below. The lower frame 63 includes a support wall 631 that supports the camshaft 671 while allowing it to rotate. The support wall 631 extends in a vertical direction (Z direction). The support wall 631 has a hole 631h in which the camshaft 671 is rotatably supported. The camshaft 671 extends through the hole 631h. Therefore, the support wall 631 can also be referred to as the shaft support portion supporting the camshaft 671. The support wall 631 is provided at each of the two ends of the lower frame 63 located on the first axial side and the second axial side. The holes 631h provided in the respective support walls 631 are substantially the same.

[0079] The upper frame 64 has a support wall 641 that supports the camshaft 671 while allowing it to rotate.

[0080] Support wall 641 extends in a vertical direction. Support wall 641 has a hole 641h in which camshaft 671 is rotatably supported. Camshaft 671 extends through hole 641h. Support wall 641 is provided at each of the two ends of upper frame 64 located on the first axial side and the second axial side. Holes 641h provided in the respective support walls 641 are substantially the same.

[0081] Grounding structure of fixing equipment

[0082] The grounding structure of the fixing device 6 will now be described. According to the first embodiment, the fixing device 6 includes a grounding structure for eliminating static electricity from the heating unit 61 of the fixing device 6. Static electricity generated in the fixing device 6 flows to the device body 2 via a static eliminator 66.

[0083] (Static Eliminator)

[0084] Now refer to Figure 1A and Figure 1B , Figure 6A and Figure 6B as well as Figures 7-9 Describe the structure of the static eliminator 66. Figure 1A and Figure 1B This is a perspective view of fixing device 6. Figure 6A This is another perspective view of fixing device 6. Figure 6B This is another perspective view of the fixing device 6, in which the cover 661 is not shown. The cover 661 is... Figure 6A As shown in the image. Figure 7 This is a top view of the fixing device 6. Figure 8 This is a perspective view of fixing device 6. Figure 9 This is a cross-sectional view of the fixing device 6.

[0085] like Figure 6A As shown in the diagram, the upper frame 64 is provided with an electrostatic eliminator 66 configured to eliminate static electricity from the fixing device 6. With respect to the first axial direction, the electrostatic eliminator 66 is located downstream of the midpoint of the band 614 defined along this axial direction.

[0086] like Figures 6A to 9 As shown in the diagram, the static eliminator 66 includes a brush 660, a first conductive plate 662, a resistor 663, a second conductive plate 664, a cover 661, a screw 665, a screw 666, and a first conductive spring 667.

[0087] Brush 660 is in contact with heating unit 61 and first conductive plate 662. First conductive plate 662 is in contact with resistor 663. Second conductive plate 664 is in contact with first conductive spring 667. Brush 660, first conductive plate 662, resistor 663 and second conductive plate 664 are all conductive. Therefore, static electricity generated in heating unit 61 is transferred from brush 660 to first conductive spring 667.

[0088] The cover 661 covers the brush 660, the first conductive plate 662, and the second conductive plate 664 from above. (Example) Figure 6A and Figure 6B As shown in the diagram, screw 665 secures the first conductive plate 662 and the cover 661 to the upper frame 64. Screw 666 secures the second conductive plate 664 and the cover 661 to the upper frame 64.

[0089] The composition of brush 660 (brush component) will now be described. For example... Figure 8 As shown in the diagram, brush 660 is fixed inside the upper frame 64. Figure 9As shown in the diagram, brush 660 is a conductive member disposed above in contact with strip 614. Brush 660 includes brush body 660a and substrate 660b. Brush body 660a is made of conductive resin. Substrate 660b is made of stainless steel called SUS (SUS is metal) and is conductive. Brush body 660a contacts the outer peripheral surface 614b (conductive layer) of strip 614, thereby electrically connecting brush body 660a and strip 614 to each other, that is, connecting them to each other. Specifically, brush 660 and heating unit 61 are electrically connected to each other. In a first embodiment, brush body 660a contacts the outer peripheral surface 614b of strip 614. Alternatively, another conductive member may be interposed between brush body 660a and strip 614, such that brush body 660a and strip 614 are electrically connected to each other. Substrate 660b is fixed to brush body 660a and upper frame 64. That is, the brush body 660a is fixed to the upper frame 64 by means of the substrate 660b. For example... Figure 8 As shown in the diagram, substrate 660b is in contact with contact portion 662b of the first conductive plate 662, described below. That is, substrate 660b and the first conductive plate 662 are electrically connected to each other. Figure 7 As shown in the diagram, the brush body 660a is in contact with the transmission member 617a. More specifically, when viewed along the vertical direction (Z direction), at least a portion of the brush body 660a located on the first axial side overlaps with the transmission member 617a.

[0090] The configuration of the first conductive plate 662 will now be described. For example... Figure 7 As shown in the diagram, the first conductive plate 662 is a conductive member located upstream of the brush 660 in the first axial direction. Figure 6B As shown in the diagram, the first conductive plate 662 has a first hole 662d. A screw 665 extends through the first hole 662d. Therefore, the first conductive plate 662 is fixed to the upper frame 64 (which is supported by the upper frame 64) by means of the screw 665. Figure 7 As shown in the diagram, the first conductive plate 662 includes contact portions 662a, 662b, and 662c. Contact portion 662a contacts the resistor 663, which is described below. That is, the first conductive plate 662 is electrically connected to the resistor 663. Figure 7 and Figure 8 As shown in the diagram, contact portion 662b is in contact with substrate 660b. That is, contact portion 662b and substrate 660b are electrically connected to each other. Therefore, the first conductive plate 662 is electrically connected to brush 660 and resistor 663. Thus, static electricity is allowed to flow from brush 660 to resistor 663.

[0091] The configuration of resistor 663 will now be described. The grounding structure according to the first embodiment includes resistor 663. Regulating the current flow through resistor 663 to the grounding terminal prevents damage to the protective layer formed on the surface of heater 611. For example... Figure 7 As shown in the diagram, a resistor 663 with a predetermined resistance is pressed towards the upper frame 64 by the contact portion 662a of the first conductive plate 662 and the contact portion 664a of the second conductive plate 664, thereby fixing it to the upper frame 64.

[0092] Resistor 663 contacts contact portion 662a, thus becoming electrically connected to the first conductive plate 662. Resistor 663 also contacts contact portion 664a of the second conductive plate 664 (described below), thus becoming electrically connected to the second conductive plate 664. Because resistor 663 is electrically connected to both the first conductive plate 662 and the second conductive plate 664, static electricity is allowed to flow from the first conductive plate 662 to the second conductive plate 664.

[0093] The configuration of the second conductive plate 664 will now be described. For example... Figure 6B As shown in the diagram, the second conductive plate 664 has a second hole 664d. A screw 666 extends through the second hole 664d. Therefore, the second conductive plate 664 is fixed to the upper frame 64 by means of a screw 665.

[0094] like Figure 7 As shown in the diagram, the second conductive plate 664 is a conductive component and includes contact portions 664a, 664b, and 664c. Contact portion 664a is in contact with resistor 663.

[0095] That is, resistor 663 and the second conductive plate 664 are electrically connected to each other. Contact portion 664b has a third hole 664h. Hook 667a of the first conductive spring 667, described below, extends through the third hole 664h and engages with contact portion 664b. Contact portion 664b contacts hook 667a of the first conductive spring 667, described below. That is, the second conductive plate 664 and the first conductive spring 667 are electrically connected to each other. Because the second conductive plate 664 is electrically connected to both resistor 663 and the first conductive spring 667, static electricity is allowed to flow from resistor 663 to the first conductive spring 667.

[0096] When Figure 7 As shown in the diagram, when viewed vertically, the contact portion 664b includes an overlapping portion 664bo that overlaps with the camshaft 671. The overlapping portion 664bo is located below the camshaft 671. Because the second conductive plate 664 is located below the camshaft 671, the rotating camshaft 671 is less likely to interfere with the second conductive plate 664 compared to a configuration where the second conductive plate 664 is located above the camshaft 671.

[0097] like Figure 1A and Figure 7 As shown in the diagram, the contact portion 664c contacts the camshaft 671 from above. The contact portion 664c can also be referred to as the camshaft contact portion. In this configuration, the charge accumulated in the camshaft 671 is allowed to be released to the main conductor portion 2A described below via the second conductive plate 664 and the pressure spring 653. That is, according to the first embodiment, the second conductive plate 664 releases not only the charge accumulated in the heating unit 61, but also the charge accumulated in the camshaft 671.

[0098] The configuration of the first conductive spring 667 will now be described. The first conductive spring 667 is a conductive component. For example... Figure 6B As shown in the diagram, the first conductive spring 667 includes a main spring 667c, a hook 667a, and a hook 667b.

[0099] Hook 667a forms one end of the first conductive spring 667. Hook 667b forms the other end of the first conductive spring 667. As described above, hook 667a engages with contact portion 664b at the third hole 664h. Hook 667b engages with upper hook 653a of the pressure spring 653 described below. That is, the first conductive plate 667 is in contact with both the second conductive plate 664 and the pressure spring 653 and is electrically conductive. The main spring 667c extends from hook 667a along a first axial direction and is connected to hook 667b. That is, the first conductive spring 667 (first spring) extends along the rotation axis direction of the pressure arm 652 and is electrically connected to the pressure spring 653.

[0100] See Figure 6A and Figure 6B The positional relationship between the main spring 667c and the frames 63 and 64 will be described. The support wall 641 of the upper frame 64 has a recessed portion 641c. The shape of the recessed portion 641c allows the main spring 667c to extend along a first axial direction from the upstream side to the downstream side through the support wall 631. The first conductive spring 667 extends along the first axial direction through the recessed portion 641c.

[0101] The portion of the support wall 631 of the lower frame 63 located at the end in the recording material conveying direction is referred to as the downstream support end 631e. For example... Figure 6AAs shown in the diagram, in the recording material transport direction, the downstream support end 631e is located between the camshaft 671 and the first conductive spring 667 (first spring). The downstream support end 631e contacts the first conductive spring 667, thereby guiding the first conductive spring 667 while restricting its movement toward the camshaft 671. This configuration reduces interference between the first conductive spring 667 and the rotating camshaft 671. In the first embodiment, the first conductive spring 667 contacts the downstream support end 631e. Alternatively, the first conductive spring 667 may be located further downstream of the downstream support end 631e in the recording material transport direction without contacting it.

[0102] See Figure 1A and Figure 1B , Figure 7 as well as Figure 12A and Figure 12B The electrical continuity between the pressure spring 653 and other components will be described. The pressure spring 653 includes an upper hook 653a, a lower hook 653b, and a main spring 653c. The upper hook 653a forms one end of the pressure spring 653, while the lower hook 653b forms the other end. The main spring 653c is connected to the upper hook 653a and the lower hook 653b and extends downward (vertically). The pressure spring 653 extends downward from the upper hook 653a to the lower hook 653b. The upper hook 653a engages with the hook 667b of the first conductive spring 667. The hook 669b of the second conductive spring 669 (described below) engages with the lower hook 653b. Thus, the pressure spring 653 is in contact with both the first conductive spring 667 and the second conductive spring 669 and is electrically connected.

[0103] like Figure 12A and Figure 12B As shown in the diagram, the pressure arm 652 has a recessed arm engagement portion 652a. The upper hook 653a engages with and is thus supported by the arm engagement portion 652a. That is, the pressure spring 653 contacts and is supported by the pressure arm 652. The lower frame 63 has a recessed frame engagement portion 63e1. The lower hook 653b engages with and is supported by the frame engagement portion 63e1.

[0104] See Figure 1A and Figure 1BThe electrical continuity between the second conductive spring 669 and other components will be described. The second conductive spring 669 includes a hook 669a, a hook 669b, and a main spring 669c. Hook 669a forms one end of the second conductive spring 669, while hook 669b forms the other end. The main spring 669c is connected to hooks 669a and 669b. The second conductive spring 669 extends from hook 669a to hook 669b in the direction of recording material transport. Hook 669a engages with the contact spring 668, described below. As described above, hook 669b engages with the lower hook 653b. Thus, the second conductive spring 669 contacts and is electrically connected to both the pressure spring 653 and the contact spring 668.

[0105] See Figure 1A and Figure 1B as well as Figure 10A and Figure 10B This will describe the electrical continuity between the contact spring 668 and other components. Figure 10A This is a front view of contact spring 668. Figure 10B This is a top view of the contact spring 668.

[0106] The contact spring 668 is a helical torsion spring made of metal wire. The contact spring 668 includes a coil portion 668a, a first arm 668b extending from one end of the coil portion 668a towards the upstream side in the attachment direction, and a second arm 668c extending from the other end of the coil portion 668 towards the downstream side in the attachment direction. The coil portion 668a is wound around a boss 63e provided on a lower frame 63, and is thus supported by the lower frame 63. That is, the boss 63e is fitted inside the coil portion 668a.

[0107] The first arm 668b includes a spring-receiving portion 668b2, an extension portion 668b3, a distal portion 668b4, and a bent portion 668b5. The first arm 668b has an electrical contact 668b1 at its distal end, which contacts the main conductor portion 2A of the device body 2, described below. The distal portion 668b4 is the portion located at the distal end of the first arm 668b. The electrical contact 668b1 can also be considered as the distal end of the first arm 668b. When the electrical contact 668b1 contacts the main conductor portion 2A, static electricity flows from the fixing device 6 to the device body 2.

[0108] A spring receiving portion 668b2 extends from one end of a coil portion 668a along the axial direction of the coil portion 668a. An extension portion 668b3 forms an angle with respect to the spring receiving portion 668b2 and extends in a direction intersecting the axial direction of the coil portion 668a. A distal portion 668b4 of the first arm extends from the extension portion 668b3, while forming an angle with respect to the extension portion 668b3 at a curved portion 668b5, and further extends in a direction orthogonal to the axial direction of the coil portion 668a. An electrical contact 668b1 forms the distal end of the first arm 668b and has a shape obtained by simply cutting a metal wire. That is, the electrical contact 668b1 has a sharp edge without any treatment such as rounding.

[0109] Although Figure 14 The electrical contact 668b1 shown has a shape obtained by cutting a metal wire at a right angle, but the electrical contact 668b1 may not necessarily need to have a fixed shape; for example, it may have a shape that conforms to the edge of the cutting tool.

[0110] The second arm 668c includes a second extension portion 668c1, a third extension portion 668c2, a stop portion 668c3, and a pressure-bearing portion 668c4. The second extension portion 668c1 extends from the other end of the coil portion 668a in a direction intersecting the axial direction of the coil portion 668a. The pressure-bearing portion 668c4 is a curved portion between the second extension portion 668c1 and the third extension portion 668c2. The third extension portion 668c2 extends in a direction orthogonal to the axial direction of the coil portion 668a, but different from the extending direction of the second extension portion 668c1. The stop portion 668c3 extends from the end of the third extension portion 668c2 away from the coil portion 668a along the axial direction of the coil portion 668a.

[0111] The spring receiving portion 668b2 receives the hook 669a of the second conductive spring 669. The second conductive spring 669 is a tension spring. The hook 669b of the second conductive spring 669 engages with the lower hook 653b of the compression spring 653. Therefore, as... Figure 1A and Figure 1B As shown in the diagram, the contact spring 668 is pushed by the second conductive spring 669 in a manner that rotates about the axis B of the boss 63e (in the direction indicated by arrow C).

[0112] When the fixing device 6 is detached from the device body 2, the bent portion 668b5 of the first arm 668b contacts the receiving surface 63f included in the lower frame 63 under the thrust of the second conductive spring 669, thereby positioning the contact spring 668. The lower frame 63 includes a first protective wall 63h located on one side relative to the distal portion 668b4 of the first arm in the axial direction of the coil portion 668a, and a second protective wall 63k located on the other side relative to the distal portion 668b4 of the first arm. That is, the distal portion 668b4 of the first arm is located in the gap between the first protective wall 63h and the second protective wall 63k. In this state, the electrical contact 668b1 does not protrude from the first protective wall 63h or the second protective wall 63k, or only slightly protrudes. Therefore, when the fixing device 6 is detached from the device body 2, the electrical contact 668b1 is protected by the first protective wall 63h and the second protective wall 63k, and it is unlikely to snag any other components.

[0113] On the other hand, when the fixing device 6 is detached from the main body 2, the pressure-bearing portion 668c4 bends outward from the lower frame 63. The lower frame 63 has a slit 63g and a stop wall 63n located downstream of the boss 63e in a direction opposite to the recording material transport direction. The slit 63g extends in a direction orthogonal to the axis B of the boss 63e. More specifically, the slit 63g extends in the recording material transport direction. The stop wall 63n is located adjacent to the slit 63g. The third extension 668c2 of the second arm 668c is fitted into the slit 63g. The stop portion 668c3 is located upstream of the stop wall 63n in the first axial direction and faces the stop wall 63n. Thus, as the second conductive spring 669 rotates in the direction of its protruding arrow C, the stop portion 668c3 contacts the stop wall 63n.

[0114] See Figure 17 This will describe the electrical conductivity between the main body 2 of the device and other components. Figure 17 This is a top view of the fixing device 6 attached to the main body 2. The main body 2 includes a conductive main conductor portion 2A. In the first embodiment, the main conductor portion 2A is an electrode. The contact spring 668 is located closer to the center of the long side of the heating unit 61 than the main conductor portion 2A.

[0115] The main conductor portion 2A is a metal plate that serves as the frame of the device body 2. The main conductor portion 2A can be electrically grounded. The main conductor portion 2A includes a contact surface 2As. The contact surface 2As forms the portion of the main conductor portion 2A located at the end in a first direction. The contact surface 2As extends along the attachment direction (+X direction). The contact surface 2As contacts and is electrically conductive with the electrical contact 668b1. Thus, the main conductor portion 2A allows static electricity to flow from the electrical contact 668b1 to ground.

[0116] Although the above description outlines the grounding structure for the fixing device 6, the brush body 660a contacts the outer peripheral surface 614b of the belt 614, thereby electrically connecting the brush body 660a and the belt 614. The brush 660a contacts and is electrically connected to the first conductive plate 662. The resistor 663 contacts and is electrically connected to the second conductive plate 664. The second conductive plate 664 contacts and is electrically connected to the first conductive spring 667. The first conductive spring 667 contacts and is electrically connected to the pressure spring 653. The pressure spring 653 contacts and is electrically connected to the second conductive spring 669. The second conductive spring 669 contacts and is electrically connected to the contact spring 668. The electrical contact 668b1 of the contact spring 668 contacts and is electrically connected to the main conductor portion 2A of the device body 2. Therefore, the main conductor portion 2A can be electrically grounded.

[0117] Here, the first conductive plate 662, resistor 663, and second conductive plate 664 can also be referred to as the first conductor portion 600a. That is, the first conductor portion 600a includes the first conductive plate 662, resistor 663, second conductive plate 664, and first conductive spring 667 (first spring). The first conductor portion 600a contacts both the brush 660 (brush component) and the pressure spring 653, and provides electrical conductivity between the brush 660 (brush component) and the pressure spring 653.

[0118] A set of second conductive springs 669 and contact springs 668 may also be referred to as the second conductor portion 600b. That is, the second conductor portion 600b includes the second conductive spring 669 and the contact spring 668. The second conductor portion 600b contacts both the pressure spring 653 and the main conductor portion 2A, and provides electrical conductivity between the pressure spring 653 and the main conductor portion 2A.

[0119] Therefore, the charge accumulated in the heating unit 61 is grounded through the brush 660, the first conductor portion 600a, and the second conductor portion 600b. This configuration makes it possible to eliminate the charge accumulated in the heating unit 61.

[0120] In the fixing device 6 according to the first embodiment, since the upper frame 64 and the lower frame 63 are made of resin, it is difficult to use the upper frame 64 and the lower frame 63 as part of the grounding structure. However, as described above, providing electrical conductivity to the main conductor portion 2A through the brush 660, the first conductor portion 600a and the second conductor portion 600b enables the discharge of charge from the heating unit 61.

[0121] In the fixing device 6 according to the first embodiment, the upper frame 64 (first frame) supports the first conductive plate 662, the resistor 663, and the second conductive plate 664. The upper frame 64 supports the first conductor portion 600a, which is attached to the upper frame 64 or guided by the upper frame 64. Because the first conductor portion 600a is supported by the upper frame 64, the stability of the first conductor portion 600a relative to external forces is improved.

[0122] As described above, the coil portion 668a is wound around the boss 63e provided on the lower frame 63, and is thus supported by the lower frame 63. The lower hook 653b engages with and is supported by the frame engagement portion 63e1. Thus, with respect to the fixing device 6 according to the first embodiment, the lower frame 63 supports the second conductor portion 600b, or the second conductor portion 600b is attached to the lower frame 63.

[0123] (Attach the fixing device to the main body of the device)

[0124] The behavior of the contact spring 668 during the process of moving the fixing device 6 to the attachment position and setting the fixing device 6 to the device body 2 will now be described. The fixing device 6 moves relative to the device body 2 in the attachment direction (+X direction) and is thus set to the attachment position. Figure 14 This is a top view of the fixing device 6 before it is set to the main body 2 of the device. Figure 15 It is a fixing device 6 from Figure 14 The position in the middle is moved to the top view in the main body 2 of the device. Figure 16 It is a fixing device 6 from Figure 15 The position in the middle is further moved to the top view in the main body 2 of the device. Figure 17 It is a fixing device 6 from Figure 16 The position in the middle is further moved into the device body 2 and set to the attachment position relative to the device body 2 in a top view.

[0125] like Figure 14 As shown in the diagram, the main conductor portion 2A includes a main upstream edge 2Ae. The main upstream edge 2Ae is the edge of the main conductor portion 2A located on the upstream side in the attachment direction. The main upstream edge 2Ae extends along a first direction (-Y direction). The end of the main upstream edge 2Ae located on the first direction side is connected to the end of the contact surface 2As located on the side opposite to the attachment direction side (-X side).

[0126] The position of the contact spring 668 before setting the fixing device 6 will be described. For example... Figure 14As shown in the diagram, before the fixing device 6 is set, the electrical contact 668b1 and the pressure-bearing portion 668c4 are located upstream of the upstream edge 2Ae of the main body in the attachment direction. In the first direction, the pressure-bearing portion 668c4 is located upstream of the contact surface 2As. A portion of the third extension 668c2 is located at the same position as the upstream edge 2Ae of the main body in the first direction. In the first direction, the electrical contact 668b1 is located downstream of the upstream edge 2Ae of the main body.

[0127] When in Figure 14 When the fixing device 6, positioned as shown in the diagram, moves relative to the main body 2 along the attachment direction, the third extension 668c2 contacts the upstream edge 2Ae of the main body. The third extension 668c2 extends along the attachment direction while oriented towards the first direction side. Thus, the third extension 668c2 is pushed by the upstream edge 2Ae of the main body, and the second arm 668c rotates counterclockwise around the boss 63e. That is, when the third extension 668c2 advances along the attachment direction, the second arm 668c, which contacts and is pushed by the upstream edge 2Ae of the main body, moves towards the -Y side. Consequently, the pressure-bearing portion 668c4 contacts the contact surface 2As. Figure 15 As the second arm 668c rotates counterclockwise, the coil portion 668a and the first arm 668b also rotate counterclockwise around the boss 63e. Therefore, as... Figure 15 As shown in the diagram, when the pressure-bearing portion 668c4 contacts the contact surface 2As, the distal portion 668b4 of the first arm reaches a position coinciding with the upstream edge 2Ae of the main body in the first direction. When in... Figure 15 When the fixing device 6, as shown in the diagram, moves further relative to the main body 2 along the attachment direction, as... Figure 16 As shown in the diagram, the distal portion 668b4 of the first arm contacts the upstream edge 2Ae of the main body. Specifically, since the second arm 668c contacts the conductor portion 2A of the main body and moves along the first direction, the distal portion 668b4 (the distal portion) of the first arm moves along the second direction opposite to the first direction and contacts the upstream edge 2Ae of the main body.

[0128] Figure 16 The diagram illustrates the state in which the distal portion 668b4 (distal portion) of the first arm begins to contact the upstream edge 2Ae of the main body. When the distal portion 668b4 of the first arm begins to contact the upstream edge 2Ae of the main body, the distal portion 668b4 (distal portion) of the first arm extends along the attachment direction while oriented towards the first direction side. Figure 16The diagram illustrates the state in which the distal portion 668b4 of the first arm begins to contact the upstream edge 2Ae of the main body. The angle θ1 formed between the direction of extension of the distal portion 668b4 of the first arm and the attachment direction is an acute angle (less than 90 degrees). If angle θ1 were an obtuse angle (greater than 90 degrees), the contact spring 668 and the upstream edge 2Ae of the main body would strongly interfere with each other, potentially causing the contact spring 668 to deform. Therefore, this disclosure configures angle θ1 as an acute angle to reduce the deformation of the contact spring 668. The predetermined value for the deformation of the contact spring 668 at angle θ1 is set within the range of 30 degrees ≥ θ1 > 0 degrees.

[0129] In the first embodiment, to make angle θ1 an acute angle, the angle θ2 formed between the extension portion 668b3 and the distal portion 668b4 of the first arm is set to an obtuse angle (greater than 90 degrees), such as... Figure 10B As shown in the diagram, angle θ2 can also be considered as the angle of bending of the curved portion 668b5 (the first curved portion). Setting angle θ2 as an obtuse angle makes it easier to set angle θ1 as an acute angle. Therefore, the deformation of the contact spring 668 is reduced. In the first embodiment, angle θ2 is set within the range of 135 degrees ± 20 degrees (155 degrees ≥ θ2 ≥ 115 degrees). If the contact spring 668 is designed such that angle θ2 becomes less than 115 degrees, deviations in production will cause angle θ2 to become 90 degrees or less. As mentioned above, if angle θ1 is an obtuse angle (greater than 90 degrees), the contact spring 668 and the upstream edge 2Ae of the body will strongly interfere with each other, causing the contact spring 668 to potentially deform. Therefore, the first embodiment adopts a configuration that satisfies θ2 ≥ 115 degrees. On the other hand, it may be difficult to produce the contact spring 668 such that angle θ2 becomes 155 degrees or greater. Therefore, considering the ease of production of the contact spring 668, the first embodiment adopts a configuration that satisfies 155 degrees ≥ θ2.

[0130] When in Figure 16 As the fixing device 6, positioned as shown in the diagram, moves further relative to the main body 2 along the attachment direction, the distal portion 668b4 of the first arm, which contacts the upstream edge 2Ae of the main body, moves toward the first direction side while advancing along the attachment direction. Consequently, the electrical contact 668b1 (distal end) is guided to and contacts the contact surface 2As. As the fixing device 6 moves further along the attachment direction, the sharp edge of the electrical contact 668b1 scrapes against the contact surface 2As while moving along it. Thus, even if the contact surface 2As is covered with any coating or oxide film, such coating or oxide film is scraped off by the electrical contact 668b1, thereby maintaining the electrical connection between the main conductor portion 2A and the electrical contact 668b1 in a good manner. Finally, the fixing device 6 is set as shown... Figure 17 The attachment location is shown in the diagram.

[0131] Eliminate charge from the rotating pressurizing component

[0132] If a charged sheet S is fed to the rotary pressure member 62, the rotary pressure member 62 may become charged. If the fixing operation is performed while the rotary pressure member 62 is charged, the fixing quality may deteriorate. Therefore, the fixing device 6 according to the first embodiment employs a structure to eliminate the charge accumulated in the rotary pressure member 62. See also Figure 18 and Figure 19 The structure for eliminating the charge accumulated in the rotating pressurizing member 62 will now be described. Figure 18 and Figure 19 This is a perspective view of the fixing device 6. The fixing device 6 includes a helical torsion spring 636. The helical torsion spring 636 includes a coil portion 636c, a first arm portion 636a, and a second arm portion 636b. The lower frame 63 has a boss 63i at its end on its first axial side (+Y side). The coil portion 636c is wound around the boss 63i and is therefore supported by the boss 63i (lower frame 63). That is, the boss 63i is fitted into the coil portion 636c. The second arm portion 636b extends from one end of the coil portion 636c toward the static eliminator 66 and engages with a groove 64b provided in the upper frame 64. In a first embodiment, the groove 64b is provided in the upper frame 64. Alternatively, a guide portion having the same function as the groove 64b may be provided as a separate component on the upper frame 64. The first arm portion 636a extends from the other end of the coil portion 636c toward the bearing 62c and contacts the bearing 62c. With the second arm portion 636b fitted in the groove 64b and the first arm portion 636a in contact with the bearing 62c, the angle formed between the first arm portion 636a and the second arm portion 636b is smaller than the free angle of the helical torsion spring 636. Therefore, the first arm portion 636a and the second arm portion 636b rotate, causing the angle formed between them to widen. More specifically, the first arm portion 636a rotates in a direction toward the bearing 62c. Thus, the contact pressure between the first arm portion 636a and the bearing 62c increases, thereby stabilizing the electrical connection. On the other hand, the second arm portion 636b rotates in a direction away from the bearing 62c. In the first embodiment, the second arm portion 636b is fitted in the groove 64b, thereby restricting the rotation of the second arm portion 636b by the groove 64b. That is, the groove 64b acts as a guide portion guiding the second arm portion 636b toward the static eliminator 66. Because the groove 64b restricts the rotation of the second arm portion 636b, the force that causes the first arm portion 636a to rotate toward the bearing 62c is maintained. Therefore, the contact pressure between the first arm portion 636a and the bearing 62c is maintained at a high level.

[0133] Bearing 62c and shaft 62a are in contact with each other. Therefore, the rotating pressure member 62, bearing 62c, and helical torsion spring 636 are electrically connected to each other. Figure 18 As shown in the diagram, the second arm portion 636b contacts the contact portion 662c. That is, the helical torsion spring 636 (the third conductor portion) contacts both the first conductor portion 600a and the bearing 62c, thereby providing an electrical connection (electrical conductivity) between the shaft 62a (rotation shaft) and the main conductor portion 2A. Thus, the rotating pressure member 62 (shaft 62a), the bearing 62c, the helical torsion spring 636, and the static eliminator 66 are electrically connected to each other.

[0134] As described above, the static eliminator 66 is electrically connected to the main conductor portion 2A. Therefore, the rotating pressure member 62 is electrically connected to the main conductor portion 2A. That is, the rotating pressure member 62 is connected to ground, which allows the charge accumulated in the rotating pressure member 62 to be eliminated. This suppresses the degradation of fixing quality caused by the charging of the rotating pressure member 62.

[0135] In the fixing apparatus 6 according to the first embodiment, the grounding structure for the rotating pressure member 62 and the grounding structure for the heating unit 61 are not independent of each other, and the grounding structure for the heating unit 61 also serves as the grounding structure for the rotating pressure member 62. This configuration releases charge from the rotating pressure member 62 via a resistor 663. The grounding configuration of the rotating pressure member 62 raises the following issue: When the transfer roller 51 and the rotating pressure member 62 transport the sheet S, the voltage applied to the transfer roller 51 can be transmitted as current through the sheet S to the rotating pressure member 62, which may reduce the transfer voltage of the transfer roller 51. This is because the rotating pressure member 62 connected to ground facilitates the flow of current from the transfer roller 51 to the rotating pressure member 62. Therefore, in the first embodiment, the resistor 663 is connected to the rotating pressure member 62. Thus, it becomes less likely for current to flow from the transfer roller 51 to the rotating pressure member 62.

[0136] In the first embodiment, since the grounding structure for the heating unit 61 also serves as the grounding structure for the rotating pressurizing member 62, no other resistors need to be added except for the resistor 663, which is different from the case where the grounding structures for the rotating pressurizing member 62 and the grounding structures for the heating unit 61 are set separately from each other.

[0137] The fixing device 6 uses a compression spring 653 as a grounding structure. A first conductor portion 600a is included in the upper frame 64, while a second conductor portion 600b is included in the lower frame 63. Thus, the first conductor portion 600a and the second conductor portion 600b are spaced apart from each other in the vertical direction. Therefore, in the first embodiment, a compression spring 653 extending in the vertical direction is used to connect the first conductor portion 600a and the second conductor portion 600b to each other. Because of the use of the compression spring 653, no additional conductive components are needed to electrically connect the first conductor portion 600a and the second conductor portion 600b to each other.

[0138] (Second Embodiment)

[0139] The second embodiment differs from the first embodiment in that the main conductor portion 2A includes an inlet portion 2AI to reduce interference between the distal portion 668b4 of the first arm and the main conductor portion 2A. Figure 20 This is a top view of the fixing device 6, which has not yet been set to the main body 2 of the device. Figure 21 It is a fixing device 6 from Figure 20 The position in the middle is further moved to the top view in the main body 2 of the device. Figure 22 It is a fixing device 6 from Figure 21 The position in the middle is further moved into the device body 2, and is set in a top view relative to the device body 2 at the attachment position. For example... Figure 20 As shown in the diagram, the main conductor portion 2A includes an introduction portion 2AI. The introduction portion 2AI acts as a guide portion guiding the distal end portion 668b4 of the first arm toward the contact surface 2As. The introduction portion 2AI has introduction surfaces 2AIs. The introduction surfaces 2AIs are guide surfaces oriented toward a first direction side and extending along the attachment direction, and are connected to the contact surface 2As. When in... Figure 20 When the fixing device 6, as shown in the diagram, moves along the attachment direction, the pressure-bearing portion 668c4 is guided to the contact surface 2As while being pushed by the guide surface 2AIs. That is, the second arm 668c is guided by the guide surface 2AIs and moves towards the first direction. As the second arm 668c rotates counterclockwise, the coil portion 668a and the first arm 668b also rotate counterclockwise around the boss 63e. Specifically, as the second arm 668c moves along the first direction, the distal portion 668b4 of the first arm moves along a second direction opposite to the first direction and contacts the guide surface 2AIs (the guide portion).

[0140] Figure 21 The diagram illustrates the state of the fixing device 6 in which the distal portion 668b4 of the first arm begins to contact the guide surface 2AIs. As described above, the guide surface 2AIs extends along the attachment direction while oriented towards the first direction side. The angle θ3 formed between the attachment direction and the guide surface 2AIs is an acute angle. Thus, the distal portion 668b4 of the first arm is guided towards the first direction side. Therefore, interference between the distal portion 668b4 of the first arm and the main conductor portion 2A is reduced. The predetermined value for the deformation of the contact spring 668 at angle θ3 is set within the range of 30 degrees ≥ θ1 > 0 degrees.

[0141] When in Figure 21As the fixing device 6, positioned as shown in the diagram, is further inserted into the main body 2, the distal portion 668b4 of the first arm, guided by the guide surface 2AIs, moves toward the first direction side while advancing along the attachment direction. The electrical contact 668b1 (distal end) is guided to the contact surface 2As. The electrical contact 668b1 moves along the attachment direction while contacting the contact surface 2As. Finally, as... Figure 22 As shown in the diagram, the fixing device 6 reaches the attachment position and is set to the device body 2.

[0142] In the second embodiment, the guide surface 2AIs guides the distal portion 668b4 of the first arm to the contact surface 2As. This reduces the deformation of the contact spring 668.

[0143] Although angle θ2 in the first embodiment is an obtuse angle, as long as angle θ1 is set to an acute angle, angle θ2 can be set to an acute angle (less than 90 degrees), such as... Figure 22 As shown in the diagram, if the angle θ2 is set within the range of 90 degrees ± 10 degrees, the contact pressure applied from the electrical contact 668b1 to the contact surface 2As becomes greater than the contact pressure when the angle θ2 is an obtuse angle. A contact spring 668 designed to form the angle θ2 within the range of 90 degrees ± 10 degrees is easier to manufacture than a contact spring designed to form an angle θ2 at a very large obtuse or acute angle.

[0144] Although the inlet portion 2AI according to the second embodiment is included in the main conductor portion 2A, the inlet portion 2AI can be separated from the main conductor portion 2A. The shape of the inlet portion 2AI can be a folded shape or a curled shape.

[0145] (Third Embodiment)

[0146] Now refer to Figure 23 The third embodiment is described. Figure 23 This is a top view of the fixing device 6. The grounding structure used in the first embodiment is configured to release static electricity through the brush 660, the first conductor portion 600a, and the second conductor portion 600b. Alternatively, the pressure arm 652 can be used as part of the grounding structure. Specifically, the pressure arm 652 can be made of a conductive material, such that the brush 660, the pressure arm 652, and the pressure spring 653 are electrically connected to each other. In this case, the grounding structure from the pressure spring 653 to the main conductor portion 2A is the same as in the first embodiment, and its description is incorporated herein by reference for the sake of brevity.

[0147] The fixing device 6 includes a conductive intermediate conductor portion 658. The intermediate conductor portion 658 is a metallic component. The intermediate conductor portion 658 can be any conductive component. For example... Figure 23As shown in the diagram, the intermediate conductor portion 658 contacts and is electrically connected to both the brush 660 and the pressure arm 652. In the third embodiment, the intermediate conductor portion 658 is electrically connected to the belt 614 via the brush 660. Therefore, stable contact is achieved with minimal force, thus preventing damage to the belt 614.

[0148] Instead of a brush 660, the intermediate conductor portion 658 directly contacts the strip 614, making the intermediate conductor portion 658 and the strip 614 electrically connected to each other. In this case, the grounding structure becomes less expensive because the brush 660 is omitted. The intermediate conductor portion 658 is separate from the drive member 617a or the pressure arm 652. Alternatively, the intermediate conductor portion 658 can be integrated with the drive member 617a or the pressure arm 652.

[0149] As an alternative, instead of setting the intermediate conductor section 658, Figure 5 The transmission member 617a shown in the diagram can be made of a conductive material. In this case, the transmission member 617a is in contact with both the belt 614 and the pressure arm 652, and is electrically connected to both of them.

[0150] (Fourth Embodiment)

[0151] Now refer to Figure 24A and Figure 24B The fourth embodiment is described. Figure 24A and Figure 24B The schematic diagram illustrates a portion of the strip 614. The outer peripheral surface 614b of the strip 614, which contacts the brush body 660a, can be formed of a coating such as fluorocarbon resin. Alternatively, for example, if the strip 614 is a conductive component such as a metal sleeve, the coating can be partially removed to expose the metal layer (conductive layer).

[0152] like Figure 24A As shown in the diagram, the strip 614 includes a conductive layer 614d and an insulating layer 614c covering the conductive layer 614d from the outer periphery of the strip 614. For example, the conductive layer 614d acts as the base layer of the strip 614. The conductive layer 614d includes an exposed portion 614cc that is not covered by the insulating layer 614c and is exposed on the outer periphery of the strip 614. The brush 660 contacts the exposed portion 614cc. Therefore, the charge accumulated in the heating unit 61 is released to ground through the aforementioned grounding structure.

[0153] Figure 24B The diagram illustrates the state in which the sheet S with toner image I is located in the pressing section np1, so that the toner image I is fixed by the fixing device 6. Figure 24BThe toner image I formed on the sheet S, as shown in the diagram, has the maximum possible size in the generatrical direction (Y direction) of the belt 614. The portion of the belt 614 that coincides with the toner image I in the generatrical direction (Y direction) of the belt 614 is referred to as the first portion 614I of the belt. At least a portion of the exposed portion 614cc is located outside the first portion 614I of the belt in the generatrical direction of the belt 614. Similarly, at least a portion of the brush 660 is located outside the first portion 614I of the belt in the generatrical direction of the belt 614. That is, in terms of the generatrical direction of the belt 614, at least a portion of the exposed portion 614cc and at least a portion of the brush 660 are located outside the area of ​​the belt 614 through which the recording material with the maximum width that can be conveyed at the pressing section np1 passes. With the exposed portion 614cc designed as described above, the impact on fixing quality is smaller compared to the case where the exposed portion 614cc is located inside the first portion 614I of the belt in the generatrical direction of the belt 614.

[0154] In the first embodiment, the first conductor portion 600a, included in the grounding structure for the rotating pressure member 62 and the grounding structure for the heating unit 61, includes a pressure spring 653. Alternatively, the first conductor portion 600a may not necessarily need to include a pressure spring 653. That is, the first conductor portion 600a includes a conductive member that contacts the second conductor portion 600b.

[0155] While this disclosure has been described with reference to embodiments, it should be understood that this disclosure is not limited to the disclosed embodiments. The scope of the appended claims should be given the broadest interpretation to cover all such modifications and equivalent structures and functions.

Claims

1. A fixing device configured to be attached to an image forming apparatus, the fixing device comprising: A heating unit comprising an annular belt and a heater, the heater being disposed on the inner circumferential side of the belt and configured to heat the belt; A pressure roller, configured to form a pressing portion with the heater across the belt; A pressure arm, configured to press the heating unit relative to the pressure roller; A conductive pressure spring is configured to push the pressure arm to press the heating unit relative to the pressure roller; A conductive bearing, configured to support the rotating shaft of the pressure roller; A frame made of resin that supports the bearing; The conductive brush component is disposed in contact with the ground. A first conductor portion is configured to contact the brush component and the pressure spring, such that the brush component and the pressure spring are electrically connected to each other; The second conductor portion is configured to contact the compression spring and the main conductor portion of the image forming apparatus, such that the compression spring and the main conductor portion are electrically connected to each other; as well as A third conductor portion is configured to contact the first conductor portion and the bearing, such that the rotating shaft and the main conductor portion are electrically connected to each other.

2. The fixing device according to claim 1, wherein the first conductor portion comprises a resistor.

3. The fixing device according to claim 1 further includes: Other frames made of resin, The first conductor portion is attached to the other frame. When the fixing device is attached to the main body of the image forming apparatus, the other frame is located above the frame, and The second conductor portion is attached to the frame.

4. The fixing device according to claim 3, The third conductor portion includes a helical torsion spring. The helical torsion spring mentioned above includes: The coil portion is supported by a boss provided on the frame; A first arm portion extending from one end of the coil portion and contacting the bearing; as well as The second arm portion extends from the other end of the coil portion and contacts the first conductor portion, and The other frame has a groove configured to engage and restrict rotation of the second arm portion.

5. The fixing device according to claim 3, The other frame includes a first guide configured to guide the surface of the recording material conveyed at the pressing section, and The surface thereon faces the heating unit.

6. The fixing device according to claim 1, The strip includes a conductive layer and an insulating layer, the insulating layer covering the conductive layer from the outer peripheral side of the strip. The conductive layer includes an exposed portion that is exposed on the outer peripheral side of the strip. The brush component is in contact with the exposed portion of the conductive layer. At least a portion of the exposed portion is located outside the area through which the recording material, having a maximum width capable of being conveyed at the press-fit portion, passes, and The width of the recording material is related to the generatrix direction of the tape.

7. The fixing device according to claim 3, further comprising: A camshaft rotatably supported by the frame; as well as A cam, configured to rotate in a manner that alters the pressing force applied from the pressure arm to the pressure roller of the heating unit, the cam being supported by and rotating with the camshaft.

8. The fixing device according to claim 7, The first conductor portion includes, when the fixing device is attached to the main body of the device, an overlapping portion that overlaps with the camshaft when viewed from a vertical direction, and When the fixing device is attached to the main body of the device, the overlapping portion is located below the camshaft.

9. The fixing device according to claim 7, The other frame supports the camshaft.

10. The fixing device according to claim 1, The first conductor portion includes a first spring, and The first spring extends along the rotation axis of the pressure arm and is electrically connected to the pressure arm.

11. The fixing device according to claim 7, The first conductor portion includes a first spring. The frame includes a shaft support portion configured to support the camshaft and extending in a vertical direction. The recording material is conveyed along the conveying direction at the pressing section, and In the case where the downstream end of the support is located between the camshaft and the first spring, the downstream end of the shaft support portion is located on the downstream side in the conveying direction.

12. The fixing device according to claim 11, The downstream end of the support is configured to guide the first spring to limit the movement of the first spring toward the camshaft.

13. The fixing device according to claim 6, The conductive layer is the base layer of the strip.

14. The fixing device according to claim 1, The second conductor portion includes a helical torsion spring, and When the fixing device is attached to the main body of the image forming apparatus, the helical torsion spring contacts the conductor portion of the main body.

15. The fixing device according to claim 1, The main conductor portion therein is an electrode.

16. The fixing device according to claim 7, The first conductor portion includes a camshaft contact portion that contacts the camshaft.

17. A fixing device, the fixing device being attached to an image forming apparatus, the fixing device comprising: A heating unit comprising an annular belt and a heater, the heater being disposed on the inner circumferential side of the belt and configured to heat the belt; A pressure roller, configured to form a pressing portion with the heater across the belt; A conductive bearing that supports the rotating shaft of the pressure roller; A frame made of resin, the frame being configured to support the bearing; The conductive brush component is disposed in contact with the ground. A first conductor portion is configured to contact the brush component in such a way that it is electrically connected to the brush component; A second conductor portion is configured to contact the first conductor portion and the main conductor portion of the image forming apparatus, such that the first conductor portion and the main conductor portion are electrically connected to each other. as well as A third conductor portion is configured to contact the first conductor portion and the bearing, such that the rotating shaft and the main conductor portion are electrically connected to each other. The second conductor portion includes a helical torsion spring. The helical torsion spring includes a coil portion and an arm extending from one end of the coil portion, and When the fixing device is attached to the main body of the device, the distal end of the arm contacts the conductor portion of the main body.

18. The fixing device according to claim 17, The main conductor portion includes electrodes, and When the fixing device is attached to the main body of the device, the distal end of the arm contacts the electrode.

Images