Fixing device

Abstract

The present disclosure relates to a fixing device mounted in an image forming apparatus including a main body conductor portion, the fixing device including: a heating unit including an endless belt and a heater; a pressure roller configured to form a nip together with the heater via the belt; a pressure arm; a pressure spring configured to bias the pressure arm, the pressure spring having electrical conductivity; a frame configured to support the heating unit and made of a resin; a brush member configured to contact the belt; a first conductor portion configured to be in contact with the brush member and the pressure spring, and electrically connecting the brush member and the pressure spring; and a second conductor portion configured to be in contact with the pressure spring and the main body conductor portion, and electrically connect the pressure spring and the main body conductor portion.

Description

Technical Field

[0001] This disclosure relates to a fixing device installed in an electrophotographic image forming apparatus. Background Technology

[0002] The fixing apparatus discussed in Japanese Patent Application Publication No. 2024-31208 includes a heating unit and a pressure roller. The heating unit includes a heater for heating the inner surface of the belt, and the pressure roller forms a clamping portion with the heater via the belt to fix the toner onto the recording material. Summary of the Invention

[0003] The present disclosure aims to provide a new type of fixing device that improves upon conventional techniques.

[0004] The various aspects of this disclosure are described below.

[0005] One aspect of this disclosure provides a fixing device configured to be mounted in an image forming apparatus and configured to fix toner onto a recording material, the image forming apparatus including a main conductor portion capable of being electrically grounded, the fixing device comprising: a heating unit including an annular belt and a heater disposed inside the belt for heating the belt; a pressure roller configured to form a clamping portion together with the heater via the belt; a pressure arm for pressing the heating unit against the pressure roller; and a pressure spring configured to... The device comprises: a pressure arm biased to press the heating unit against the pressure roller; a pressure spring having electrical conductivity; a frame configured to support the heating unit and made of resin; a brush member configured to contact the belt and having electrical conductivity; a first conductor portion configured to contact and electrically connect the brush member and the pressure spring; and a second conductor portion configured to contact and electrically connect the pressure spring and the main conductor portion.

[0006] The features of this disclosure will become apparent from the following description of embodiments with reference to the accompanying drawings. The embodiments will now be described by way of example. Attached Figure Description

[0007] Figure 1A and Figure 1B These are perspective views of the fixing apparatus according to the first embodiment.

[0008] Figure 2 This is a cross-sectional view of the image forming apparatus according to the first embodiment.

[0009] Figure 3This is a cross-sectional view of the fixing device according to the first embodiment.

[0010] Figure 4 This is a cross-sectional view of the fixing device according to the first embodiment.

[0011] Figure 5 This is an exploded perspective view of the fixing apparatus according to the first embodiment.

[0012] Figure 6A and Figure 6B These are perspective views of the fixing apparatus according to the first embodiment.

[0013] Figure 7 This is a top view of the fixing device according to the first embodiment.

[0014] Figure 8 This is a perspective view of the fixing device according to the first embodiment.

[0015] Figure 9 This is a cross-sectional view of the fixing device according to the first embodiment.

[0016] Figure 10A and Figure 10B These are the front view and plan view of the contact spring according to the first embodiment.

[0017] Figure 11A This is a front view of the fixing device illustrated, and Figures 11B to 11D These are cross-sectional views of the fixing apparatus according to the first embodiment, respectively.

[0018] Figure 12A and Figure 12B The figures are cross-sectional views of the fixing apparatus according to the first embodiment.

[0019] Figure 13 This is an exploded perspective view of the fixing apparatus according to the first embodiment.

[0020] Figure 14 This is a top view of the fixing device according to the first embodiment.

[0021] Figure 15 This is a top view of the fixing device according to the first variant example.

[0022] Figure 16A and Figure 16B The respective illustrations are schematic diagrams of the fixing device according to the second modification example. Detailed Implementation

[0023] An embodiment of the present disclosure (first embodiment) will now be described with reference to the accompanying drawings. The dimensions, materials, shapes, and relative positions of the components in the following embodiments may be appropriately changed depending on the construction of the device to which the present disclosure is applied and various conditions. Therefore, unless otherwise specified, the scope of the present disclosure is not limited to this embodiment.

[0024] Figure 2 This is a cross-sectional view of the electrophotographic image forming apparatus 1 using the fixing device of this embodiment. In the following description, as... Figure 2 As shown, the vertical direction in which the image forming device 1 is mounted on the horizontal plane is defined as the Z direction ( Figure 3 The direction intersecting the Z direction is defined as the Y direction. The Y direction is parallel to the rotation axis of the pressure arm 652 described below. The direction intersecting both the Z and Y directions is defined as the X direction. The X direction is parallel to the direction in which the heating unit 61 conveys the recording material located at the clamping part. The X and Y directions can be horizontal. The X, Y, and Z directions are orthogonal to each other. As needed, the directions of the arrows x, y, and z shown in the various figures are respectively referred to as the +x side, +y side, and +z side, and the opposite directions are respectively referred to as the -x side, -y side, and -z side. In the following description, the direction of conveying the recording material at the clamping part np1 described below is referred to as the recording material conveying direction (+X direction). The rotation axis of the pressure arm 652 described below is referred to as the axial direction. In the axial direction, the direction from the heating unit 61 described below toward the electrical contact part 668b1 is referred to as the first axial direction (+Y direction). In the axial direction, the direction opposite to the first axial direction is referred to as the second axial direction (-Y direction). The Y direction is also the length direction of the heating unit 61. The Y direction is the direction of the busbar with 614.

[0025] <First Embodiment> The fixing unit 6 according to the first embodiment will now be described.

[0026] [Structure of an image forming device] Reference Figure 2 The structure 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 unit 6. The processing cartridge 10 is detachably attached to the apparatus body 2. The fixing unit 6 is detachably attached to the apparatus body 2. Alternatively, the fixing unit 6 can be installed in the apparatus body 2. The fixing unit 6 can also be attached in a non-detachable manner.

[0027] The main body 2 includes a paper feed tray 3, a sheet feed unit 4, a transport path P, a transfer roller 51, a sheet discharge unit 7, a paper discharge tray 8, a laser scanner 9, and an opening / closing door 21. The processing cartridge 10 includes a photosensitive drum 11 and a developing roller 12 serving as a developer carrier. The processing cartridge 10 also contains developer. The opening / closing door 21 is pivotally supported about a pivot axis 21a and can move between a closed position (open) and an open position (closed) of the opening 2a. When the opening / closing door 21 is in the open position (open), the processing cartridge 10 can be attached to and detached from the main body 2 via the opening 2a.

[0028] The sheet feeding unit 4 includes a paper feed roller 41, a separation roller 42, a separation pad 42a, and a pair of transport rollers 43. The sheet S stored in the paper feed tray 3 is transported by the sheet feeding unit 4 to the transport path P based on the printing start signal, and is transported toward the transfer roller 51 via a pair of alignment rollers 44.

[0029] When the sheet S is conveyed to the predetermined position, an image formation start signal is emitted to initiate the image formation process. The photosensitive drum 11, driven by a drive source (motor), is uniformly charged to a predetermined potential by a charging unit. Based on image information, light emitted by the laser scanner 9 exposes the charged surface of the photosensitive drum 11, eliminating the charge in the exposed portion and forming an electrostatic latent image. Toner in the processing cartridge 10 is carried by the developing roller 12 and is supplied to the photosensitive drum 11 based on the electrostatic latent image to develop the latent image. Thus, on the photosensitive drum 11, the electrostatic latent image is visually converted into a toner image.

[0030] The transfer roller 51 is arranged opposite to the photosensitive drum 11 of the processing cartridge 10. When the sheet S, conveyed by the alignment roller 44, passes through the clamping part between the photosensitive drum 11 and the transfer roller 51, voltage is applied from the device body 2 to the transfer roller 51 to transfer 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 unit 6, which includes a heating unit 61 and a pressing and rotating member 62. The fixing unit 6 is a fixing device that fixes the toner (developer) onto the recording material. When the sheet S passes through the clamping part between the heating unit 61 and the pressing and rotating member 62, the unfixed image already transferred onto the sheet S is heated and pressed to fix it onto the surface of the sheet S. The sheet S with the fixed toner image is discharged to the paper discharge tray 8 via the sheet discharge unit 7.

[0031] [Construction of the fixing unit] The construction of fixing unit 6 will now be described. Figure 3 This is a plan view of fixing unit 6. (Example) Figure 3As shown, the heating unit 61 includes a heater 611, a retainer 612, a support bar 613, and a belt 614. The heater 611 is disposed inside the belt 614 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 opposite to the first surface 611a, and the first surface 611a is supported by the retainer 612.

[0032] The retainer 612 is made of a heat-resistant resin such as polyphenylene sulfide (PPS) or a liquid crystal polymer, and has a guide surface 612a and a support wall 612b. The guide surface 612a contacts the inner circumferential surface 614a of the belt 614 to guide the belt 614, and the support wall 612b has a support surface 612b1 for supporting the heater 611. The support surface 612b1 of the support wall 612b contacts the first surface 611a of the heater 611. The strut 613 is a member that supports the retainer 612 and is formed by bending a sheet material (e.g., a steel plate with a thickness of 1.6 mm) with a rigidity greater than that of the retainer 612 into a generally U-shape.

[0033] The belt 614 is an annular belt with heat resistance and flexibility, and is formed, for example, from a metal sleeve such as stainless steel coated with fluororesin or a laminated structure composed of polyimide resin, silicone rubber, fluororesin, etc. A heater 611, a retainer 612, and a support 613 are arranged inside the belt 614, and the belt 614 is configured to rotate about these components. The inner circumferential surface 614a of the belt 614 contacts the second surface 611b of the heater 611.

[0034] The pressing rotating member 62 (pressure roller) has a metal shaft 62a and a roller 62b made of an elastic body covering the shaft 62a, and is pressed against the heater 611 via a belt 614. The pressing rotating member 62 and the heater 611, together with the belt 614 sandwiched between the pressing rotating member 62 and the heater 611, form a clamping portion np1 that clamps, heats, and presses the sheet S. That is, the pressing rotating member 62 (pressure roller) forms the clamping portion np1 together with the heater 611 via the belt 614. Therefore, the pressing rotating member 62 heats and presses the sheet S together with the heater 611 at the clamping portion np1.

[0035] The pressing and rotating member 62 is configured to rotate by a driving force transmitted from a drive source included in the image forming apparatus 1. The belt 614 rotates along with the pressing and rotating member 62. A sheet S with a toner image transferred onto it is conveyed between the pressing and rotating member 62 and the heated belt 614 for heat fixing of the toner image.

[0036] Now, refer to Figure 4 The frame structure of fixing unit 6 is described. Figure 4 This is a plan view of the fixing unit 6. The fixing unit 6 includes an upper frame 64 and a lower frame 63. The lower frame 63 may also be referred to as the first frame, and the upper frame 64 may also be referred to as the second frame. The lower frame 63 is a frame that supports the heating unit 61 and the pressing and rotating member 62. The upper frame 64 is located above the lower frame 63 and covers the heating unit 61. The lower frame 63 and the upper frame 64 are resin members formed from non-conductive molding members (resin members). The upper frame 64 has 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 upper surface of the sheet S transported along the recording material transport direction. The lower frame 63 has 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 transported along the recording material transport direction.

[0037] Now, refer to Figure 5 The construction of the lower frame 63 supporting the pressing and rotating member 62 is described. Figure 5 This is an exploded perspective view of the fixing unit 6. The lower frame 63 has guide rails 63b at its ends in the first axial direction and the second axial direction. The guide rails 63b extend in the vertical direction and support the retainer 612 in a manner that allows it to move in the vertical direction. The two guide rails 63b are opposite to each other and engage with grooves 617a1 and 617b1 respectively provided in the transmission members 617a and 617b.

[0038] The fixing unit 6 includes bearings 62c and 62d. The ends of shaft 62a in a first axial direction and in a second axial direction are supported by bearings 62c and 62d, respectively. 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 corresponding to the protrusions. In this embodiment, the protrusion-recession relationship can be reversed. The configuration for fixing bearings 62c and 62d to the lower frame 63 is not limited to a protrusion-recession configuration.

[0039] [Structure of the pressure mechanism] The structure of the pressure mechanism of the fixing unit 6 will now be described. Figure 11A This is the front view of fixing unit 6. Figures 11B to 11D yes Figure 11A Cross-sectional view.

[0040] like Figures 11A to 11DAs shown, the fixing unit 6 has a pressure mechanism 65 that presses the heating unit 61 against the pressing and rotating member 62. The pressure mechanism 65 is provided at the ends of the lower frame 63 in the first axial direction and at the ends of the lower frame 63 in the second axial direction. Therefore, it can also be said that the pressure mechanism 65 is supported by the lower frame 63. The pressure mechanism 65 provided at the ends of the lower frame 63 in the first axial direction and the pressure mechanism 65 provided at the ends of the lower frame 63 in the second axial direction have substantially the same structure. Since the description of the pressure mechanism 65 provided on the first axial direction side also applies to the pressure mechanism 65 provided on the second axial direction side, for the sake of brevity, the description of the pressure mechanism 65 provided on the second axial direction side is incorporated herein by reference and will not be repeated.

[0041] Each pressure mechanism 65 includes a transmission member 651, a pressure arm 652, and a pressure spring 653. The pressure arm 652 is supported by a lower frame 63. More specifically, the pressure arm 652 is supported by a support portion 64d of the lower frame 63 in a manner rotatable about a central axis x1 of the support portion 64d. The support portion 64d is a generally cylindrical protrusion.

[0042] The pressure arm 652 presses down on the transmission member 651 from above, causing the transmission member 651 to move downward. Therefore, the transmission member 651 presses down on the support bar 613. As the support bar 613 moves downward, the heating unit 61, including the support bar 613, is pressed towards the pressing rotating member 62. The pressure spring 653 is a conductive tension helical spring that biases the pressure arm 652 to press the heating unit 61 against the pressing rotating member 62. The pressure spring 653 engages with the lower frame 63 and the pressure arm 652. When the pressure spring 653 biases the pressure arm 652, the pressure arm 652 causes the transmission member 651 to move downward. Therefore, the pressure arm 652 presses the heating unit 61 against the pressing rotating member 62 (pressure roller).

[0043] [Construction of the pressure relief mechanism] Now, refer to Figure 12A , Figure 12B and Figure 13 The structure of the pressure release mechanism provided in the fixing unit 6 is described.

[0044] Figure 12A and Figure 12B This is a cross-sectional view of fixing unit 6. Figure 12A The illustration shows the pressurized state of the pressure relief mechanism 67 applying pressure. Figure 12B The diagram illustrates the pressure release state of the pressure release mechanism 67, where the applied pressure has been released. Figure 13This is an exploded perspective view of the upper frame 64, lower frame 63, and camshaft 671, wherein certain components such as the heating unit 61 and the pressing rotating member 62 are not shown. The pressure relief mechanism 67 is a clamping pressure relief mechanism that changes the clamping pressure at the clamping portion np1 between the heating unit 61 and the pressing rotating member 62. The pressure relief mechanism 67 includes a camshaft 671 and a cam 672.

[0045] like Figure 12A and Figure 12B As shown, the camshaft 671 is rotatable about axis X2. The camshaft 671 extends axially and is made of conductive metal. Figure 13 As shown, cam 672 is fixed to (and supported by) the end of camshaft 671 in the first axial direction and the end of camshaft 671 in the second axial direction. Cam 672 is supported to rotate together with camshaft 671. Cam 672 is disposed on the end side of lower frame 63 in the first axial direction and the end side of lower frame 63 in the second axial direction. Cam 672 disposed on the end side of lower frame 63 in the first axial direction and cam 672 disposed on the end side of lower frame 63 in the second axial direction have substantially the same structure.

[0046] Each cam 672 presses against the pressure arm 652 against the biasing force of the pressure spring 653. Therefore, the cam 672 rotates to change the pressing force of the pressure arm 652 against the pressing rotation member 62 of the heating unit 61. The cam 672 can... Figure 12A The pressure application location shown is... Figure 12B Rotate between the pressure release positions shown.

[0047] To release the pressurized state, the camshaft 671 rotates, thereby causing the cam 672 to rotate. When the cam 672 rotates, the pressure arm 652, which is in contact with the cam 672, moves away from the transmission member 651 in the opposite direction to the direction in which the transmission member 651 presses the support bar 613.

[0048] This design reduces the pressure required to press the heating unit 61 toward the pressing rotating member 62.

[0049] Now, refer to Figure 13 The support structure for the camshaft 671 is described. The lower frame 63 has a support wall 63l that rotatably supports the camshaft 671. The support wall 63l extends in the vertical direction (Z direction). The support wall 63l has a hole 631h that rotatably supports the camshaft 671. The camshaft 671 passes through the hole 631h. Therefore, the support wall 63l can also be referred to as a shaft support portion supporting the camshaft 671. The support wall 63l is provided on the end side of the lower frame 63 in the first axial direction and on the end side of the lower frame 63 in the second axial direction. The support wall 63l has substantially the same hole 631h.

[0050] The upper frame 64 has a support wall 641 that rotatably supports the camshaft 671.

[0051] The support wall 641 extends vertically. The support wall 641 has a hole 641h that rotatably supports the camshaft 671. The camshaft 671 passes through the hole 641h. The support wall 641 is disposed on the end side of the upper frame 64 in a first axial direction and on the end side of the lower frame 63 in a second axial direction. The support wall 641 has substantially the same hole 641h.

[0052] [Grounding configuration of the fixing unit] The grounding configuration of the fixing unit 6 will now be described. In this embodiment, the fixing unit 6 has a grounding configuration for eliminating static electricity generated in the heating unit 61 of the fixing unit 6. Static electricity generated in the fixing unit 6 flows to the device body 2 via the static eliminator 66.

[0053] Static Eliminator Reference Figure 1A , Figure 1B , Figure 6A , Figure 6B as well as Figures 7 to 9 The construction of the static eliminator 66 is described. Figure 1A and Figure 1B This is a perspective view of fixing unit 6. Figure 6A This is a perspective view of fixing unit 6. Figure 6B This is a perspective view of fixing unit 6, in which Figure 6A The cover 661 shown is not visible.

[0054] Figure 7 This is a top view of fixing unit 6. Figure 8 This is a perspective view of fixing unit 6. Figure 9 This is a cross-sectional view of fixing unit 6.

[0055] like Figure 6A As shown, an electrostatic eliminator 66 for eliminating static electricity generated in the fixing unit 6 is attached to the upper frame 64. In the first axial direction, the electrostatic eliminator 66 is located downstream of the midpoint 614m of the band 614.

[0056] like Figure 6A , Figure 6B as well as Figures 7 to 9 As shown, the static eliminator 66 includes a brush 660, a first conductive plate 662, a resistor 663, a second conductive plate 664, a cover 661, screws 665 and 666, and a first conductive spring 667.

[0057] 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 conductive. Therefore, static electricity generated in heating unit 61 is transferred from brush 660 to first conductive spring 667.

[0058] Cover 661 covers brush 660, first conductive plate 662, and second conductive plate 664 from above. (Example) Figure 6A and Figure 6B As shown, screw 665 secures the first conductive plate 662 together with the cover 661 to the upper frame 64. Screw 666 secures the second conductive plate 664 together with the cover 661 to the upper frame 64.

[0059] The construction of brush 660 (brush component) will be described. For example... Figure 8 As shown, brush 660 is fixed inside the upper frame 64. Figure 9 As shown, brush 660 is a conductive member that contacts strip 614 from above. Brush 660 includes brush body 660a and substrate 660b. Brush body 660a is made of conductive resin. Substrate 660b is made of stainless steel (SUS) as a metal and is conductive. Brush body 660a contacts surface 614b of strip 614, and brush body 660a is electrically connected to strip 614. Therefore, brush 660 is electrically connected to heating unit 61. In this embodiment, brush body 660a contacts surface 614b of strip 614. However, conductive members may be arranged between brush body 660a and strip 614 to electrically connect brush body 660a and strip 614. Substrate 660b is a plate fixed to brush body 660a and upper frame 64. Therefore, brush body 660a is fixed to upper frame 64 via substrate 660b. Figure 8 As shown, substrate 660b is in contact with contact portion 662b of the first conductive plate 662 described below. Therefore, substrate 660b is electrically connected to the first conductive plate 662. Figure 7 As shown, the brush body 660a is in contact with the transmission member 617a. More specifically, when viewed from the vertical direction (Z direction), at least a portion of the brush body 660a overlaps with the transmission member 617a in the first axial direction.

[0060] The construction of the first conductive plate 662 will now be described. For example... Figure 7 As shown, the first conductive plate 662 is a conductive member located upstream of the brush 660 in the first axial direction. Figure 6A and Figure 6BAs shown, a first hole 662d is formed in a portion of the first conductive plate 662, and a screw 665 passes through the first hole 662d. Therefore, the first conductive plate 662 is fixed to (and supported by) the upper frame 64 by the screw 665. Figure 7 As shown, the first conductive plate 662 includes contacts 662a, 662b, and 662c. Contact 662a contacts the resistor 663 described below. Therefore, the first conductive plate 662 is electrically connected to the resistor 663. Figure 7 and Figure 8 As shown, contact portion 662b is in contact with substrate 660b. In other words, contact portion 662b is electrically connected to substrate 660b. Since the first conductive plate 662 is electrically connected to brush 660 and resistor 663, static electricity can flow from brush 660 to resistor 663.

[0061] The construction of resistor 663 will now be described. The grounding configuration in this embodiment includes resistor 663. Gradually releasing current to ground via resistor 663 prevents damage to the protective layer formed on the surface of heater 611. Figure 7 As shown, a resistor 663 with a predetermined resistance is pressed toward 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 to fix it to the upper frame 64.

[0062] Resistor 663 is in contact with contact portion 662a and is electrically connected to the first conductive plate 662. Resistor 663 is also in contact with contact portion 664a of the second conductive plate 664 (described below) and is 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 can flow from the first conductive plate 662 to the second conductive plate 664.

[0063] The construction of the second conductive plate 664 will now be described. For example... Figure 6A and Figure 6B As shown, a second hole 664d is formed in the second conductive plate 664, and a screw 666 passes through the second hole 664d. Therefore, the second conductive plate 664 is fixed to the upper frame 64 by screws 665.

[0064] like Figure 7 As shown, the second conductive plate 664 is a conductive member and includes contact portions 664a, 664b, and 664c. Contact portion 664a is in contact with resistor 663.

[0065] Resistor 663 is electrically connected to the second conductive plate 664. A third hole 664h is formed in the contact portion 664b. The hook 667a of the first conductive spring 667 (described below) passes through the third hole 664h and engages with the contact portion 664b. The contact portion 664b contacts the hook 667a of the first conductive spring 667 (described below). In other words, the second conductive plate 664 is electrically connected to the first conductive spring 667. Since the second conductive plate 664 is electrically connected to the resistor 663 and the first conductive spring 667, static electricity can flow from the resistor 663 to the first conductive spring 667.

[0066] like Figure 7 As shown, when viewed from the vertical direction, the contact portion 664b has an overlapping portion 664bo that overlaps with the camshaft 671. The overlapping portion 664bo is located below the camshaft 671. By arranging the second conductive plate 664 below the camshaft 671 in this manner, the possibility of the rotational operation of the camshaft 671 interfering with the second conductive plate 664 is lower compared to a configuration in which the second conductive plate 664 is arranged above the camshaft 671.

[0067] Contact portion 664c contacts the camshaft 671 from above. That is, contact portion 664c is the camshaft contact portion. This configuration allows the charge on the camshaft 671 to be released via the second conductive plate 664.

[0068] The construction of the first conductive spring 667 will now be described. The first conductive spring 667 is a conductive component. For example... Figure 6A and Figure 6B As shown, the first conductive spring 667 has a main spring 667c and hooks 667a and 667b.

[0069] Hook 667a is one end of the first conductive spring 667, and hook 667b is the other end of the first conductive spring 667. As described above, hook 667a engages with contact portion 664b through third hole 664h. Hook 667b engages with upper hook 653a of pressure spring 653 described below. In other words, the first conductive spring 667 is in contact with and electrically connected to both the second conductive plate 664 and pressure spring 653. Main spring 667c extends from hook 667a along a first axial direction and connects to hook 667b. Therefore, the first conductive spring 667 (first spring) extends along the rotation axis of pressure arm 652 and is electrically connected to pressure spring 653.

[0070] Now, refer to Figure 6AThe positional relationship between the main spring 667c and the frame is described. A groove shape 641c is formed in each support wall 641 of the upper frame 64. The groove shape 641c allows the main spring 667c to pass from the upstream side of the support wall 63l to the downstream side along a first axial direction. The first conductive spring 667 passes through the groove shape 641c and extends along the first axial direction.

[0071] The end of each support wall 63l of the lower frame 63 in the material conveying direction is referred to as the downstream support end 631e. For example... Figure 6A As shown, in the recording material transport direction, the downstream support end 631e is located between the camshaft 671 and the first conductive spring (first spring) 667. The downstream support end 631e contacts the first conductive spring 667 to guide the first conductive spring 667, thereby limiting the movement of the first conductive spring 667 in the direction toward the camshaft 671. This configuration reduces the possibility of interference between the rotation of the camshaft 671 and the first conductive spring 667. In this embodiment, the first conductive spring 667 is configured to contact the downstream support end 631e. However, the first conductive spring 667 may be arranged further downstream of the downstream support end 631e in the recording material transport direction, such that the first conductive spring 667 does not contact the downstream support end 631e.

[0072] Now, refer to Figure 1A , Figure 1B , Figure 7 , Figure 12A and Figure 12B The conductive structure of the pressure spring 653 is described. The pressure spring 653 includes an upper hook 653a, a lower hook 653b, and a main spring 653c. One end of the pressure spring 653 is the upper hook 653a, and the other end is the lower hook 653b. The main spring 653c is connected to the upper hook 653a and the lower hook 653b and extends downward (vertically). The pressure spring 653 can be described as extending 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. Therefore, the pressure spring 653 is in contact with and electrically connected to both the first conductive spring 667 and the second conductive spring 669.

[0073] like Figure 12A and Figure 12B As shown, the pressure arm 652 includes an arm engagement portion 652a, which is a recessed portion. The upper hook 653a is supported by engaging with the arm engagement portion 652a. In other words, the pressure spring 653 contacts and is supported by the pressure arm 652. The lower frame 63 includes a frame engagement portion 63e1, which is a recessed portion. The lower hook 653b engages with and is supported by the frame engagement portion 63e1.

[0074] Now, refer to Figure 1A and Figure 1B The conductive structure of the second conductive spring 669 is described. The second conductive spring 669 has hooks 669a and 669b and a main spring 669c. One end of the second conductive spring 669 is hook 669a, and the other end is hook 669b. 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 recording material transport direction. 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 is in contact with and electrically connected to both the pressure spring 653 and the contact spring 668.

[0075] Now, refer to Figure 1A , Figure 1B , Figure 10A and Figure 10B The conductive structure of the contact spring 668 is described. Figure 10A This is a front view of contact spring 668. Figure 10B This is a top view of contact spring 668.

[0076] The contact spring 668 is a torsion coil spring made of a single metal wire. The contact spring 668 has a coil portion 668a, a first arm 668b extending from one end of the coil portion 668a, and a second arm 668c extending from the other end in a direction different from that of the first arm 668b. At the end of the first arm 668b that contacts the main conductor portion 2A of the device body 2 (described below), there is a spring engagement portion 668b2, an extension portion 668b3, a hook portion 668b4, a bend portion 668b5, and an electrical contact portion 668b1. Through the contact portion 668b1 with the main conductor portion 2A, static electricity flows from the fixing unit 6 toward the device body 2.

[0077] The spring engagement portion 668b2 extends from one end of the coil portion 668a along the axial direction of the coil portion 668a. The extension portion 668b3 bends from the spring engagement portion 668b2 and extends in a direction intersecting the axial direction of the coil portion 668a. The hook portion 668b4 bends from the extension portion 668b3 at the bend portion 668b5 and extends in a direction orthogonal to the axial direction of the coil portion 668a. The electrical contact portion 668b1 is the end of the first arm 668b, formed by cutting but without any rounding or other processing, and has a sharp edge. Figure 10A and Figure 10B The electrical contact 668b1 is illustrated as a metal wire cut at a near right angle, but the electrical contact 668b1 can have an irregular shape, such as a shape that reflects the shape of the cutting tool blade.

[0078] The second arm 668c has a second extension 668c1, a third extension 668c2, a retaining portion 668c3, and a pressing portion 668c4. The second extension 668c1 extends from the other end of the coil portion 668a in a direction intersecting the axial direction of the coil portion 668a. The pressing portion 668c4 bends from the second extension 668c1 toward the third extension 668c2. The third extension 668c2 extends in a direction orthogonal to the axial direction of the coil portion 668a and different from the extending direction of the second extension 668c1. The retaining portion 668c3 extends from the end of the third extension 668c2 away from the coil portion 668a in the axial direction of the coil portion 668a.

[0079] The hook 669a at one end of the second conductive spring 669 engages with the spring engagement portion 668b2. The second conductive spring 669 is a tension spring. The hook 669b at the other end of the second conductive spring 669 engages with the lower hook 653b of the compression spring 653. With this configuration, as... Figure 1A and Figure 1B As shown, the contact spring 668 is biased by the second conductive spring 669 to rotate about the axis B of the boss 63e (in the direction of arrow C).

[0080] When the fixing unit 6 is not attached to the device body 2, under the biasing force of the second conductive spring 669, the bent portion 668b5 of the first arm 668b abuts against the abutment surface 63f provided on the lower frame 63 to determine the orientation of the bent portion 668b5. The lower frame 63 has a first protective wall 63h and a second protective wall 63k. The first protective wall 63h is located on one side of the hook portion 668b4 in the axial direction b of the spiral portion 668a, while the second protective wall 63k is located on the other side of the hook portion 668b4. In other words, the hook portion 668b4 is located in the gap between the first protective wall 63h and the second protective wall 63k. In this case, the electrical contact portion 668b1 does not protrude from the first protective wall 63h and the second protective wall 63k, or only slightly protrudes from the first protective wall 63h and the second protective wall 63k. With this structure, when the fixing unit 6 is not attached to the main body 2 of the device, the electrical contact part 668b1 is protected by the first protective wall 63h and the second protective wall 63k, and is not easily snagged on other objects.

[0081] On the other hand, when the fixing unit 6 is not attached to the device body 2, the pressing part 668c4 bends outward from the lower frame 63. The lower frame 63 has a slit 63g and a detachment wall 63n 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 of the boss 63e. More specifically, the slit 63g extends in the recording material transport direction. The detachment wall 63n is arranged adjacent to the slit 63g. The third extension 668c2 of the second arm 668c extends into the slit 63g. The detachment part 668c3 is located upstream of the detachment wall 63n and opposite to the detachment wall 63n in the first axial direction. With this configuration, when the second conductive spring 669 rotates in the direction of arrow C (i.e., the direction in which the pressing part 668c4 protrudes), the detachment part 668c3 abuts against the detachment wall 63n.

[0082] Now, refer to Figure 14 The conductive structure of the main body 2 of the device is described. Figure 14 This is a top view of the fixing unit 6. The device body 2 includes a conductive main conductor portion 2A. In this embodiment, the main conductor portion 2A is an electrode. The main conductor portion 2A is a metal plate that serves as a frame for the device body 2. The main conductor portion 2A is electrically groundable. The main conductor portion 2A is in contact with and electrically connected to the electrical contact portion 668b1. Therefore, static electricity flowing from the main conductor portion 2A to the electrical contact portion 668b1 can flow into the ground.

[0083] The grounding configuration of the fixing unit 6 has been described. As described above, the brush body 660a contacts the surface 614b of the tape 614, and the brush body 660a is electrically connected to the tape 614. The brush 660 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 portion 668b1 of the contact spring 668 contacts and is electrically connected to the main conductor portion 2A of the device body 2. The main conductor portion 2A can be electrically grounded.

[0084] The first conductive plate 662, resistor 663, second conductive plate 664, and pressure spring 653 can be collectively referred to as the first conductor section 600a. In other words, the first conductor section 600a includes the first conductive plate 662, resistor 663, second conductive plate 664, and first conductive spring 667 (first spring).

[0085] The first conductor portion 600a is in contact with both the brush 660 (brush member) and the pressure spring 653, thereby electrically connecting the brush 660 (brush member) and the pressure spring 653.

[0086] The second conductive spring 669 and the contact spring 668 can be collectively referred to as the second conductor portion 600b. In other words, the second conductor portion 600b includes the second conductive spring 669 and the contact spring 668. The second conductor portion 600b is in contact with both the pressure spring 653 and the main conductor portion 2A, thereby electrically connecting the pressure spring 653 and the main conductor portion 2A.

[0087] Therefore, the charge generated on the heating unit 61 is discharged to the ground via the brush 660, the first conductor portion 600a, and the second conductor portion 600b. This configuration eliminates the charge in the heating unit 61.

[0088] In the fixing unit 6 of this 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 parts of the grounding structure. However, as described above, the charge generated in the heating unit 61 can be released by electrically connecting the fixing unit 6 to the main conductor 2A via the brush 660, the first conductor portion 600a and the second conductor portion 600b.

[0089] In the fixing unit 6 of this embodiment, the upper frame 64 (second frame) supports the first conductive plate 662, the resistor 663, and the second conductive plate 664. Therefore, it can be said that the upper frame 64 supports the first conductor portion 600a. It can also be said that the upper frame 64 guides the first conductor portion 600a. By supporting the first conductor portion 600a in this way with the upper frame 64, the stability of the first conductor portion 600a against external forces can be improved.

[0090] <First Variation> Now, refer to Figure 15 The first variation is described. Figure 15 This is a top view of the fixing unit 6. In the first embodiment, the grounding configuration is configured to release static electricity through the brush 660, the first conductor portion 600a, and the second conductor portion 600b. However, the pressure arm 652 can be part of the grounding configuration. The pressure arm 652 can be made of a conductive member, and the brush 660, the pressure arm 652, and the pressure spring 653 can be electrically connected. In this case, the grounding configuration from the pressure spring 653 to the main conductor portion 2A is the same as in the first embodiment. Therefore, its description is incorporated herein by reference and will not be repeated.

[0091] The fixing unit 6 includes a conductive intermediate conductor portion 658. The intermediate conductor portion 658 can be a metallic component, but it can also be any conductive component. Figure 15As shown, the intermediate conductor portion 658 contacts and is electrically connected to the brush 660 and the pressure arm 652. In this modified example, the intermediate conductor portion 658 contacts and is electrically connected to the belt 614 via the brush 660. This allows for stable contact with the belt 614 with a weak force that does not damage it.

[0092] The intermediate conductor portion 658 can directly contact the belt 614 to electrically connect the intermediate conductor portion 658 and the belt 614 without the brush 660. In this case, since the brush 660 is not provided, the grounding structure can be achieved at a low cost. The intermediate conductor portion 658 is separate from the transmission member 617 or the pressure arm 652, but it is also possible to integrate the intermediate conductor portion 658 with the transmission member 617 or the pressure arm 652.

[0093] Without the intermediate conductor portion 658 Figure 5 The transmission member 617 shown can be made of a conductive material. In this case, the transmission member 617 is in contact with and electrically connected to both the belt 614 and the pressure arm 652.

[0094] <Second Variation> Now, refer to Figure 16A and Figure 16B The second variation is described below. Figure 16A and Figure 16B These are schematic diagrams showing portions of the strip 614. The surface 614b of the strip 614 that contacts the brush body 660a may be a coating such as fluororesin; however, if the strip 614 is made of a conductive material such as a metal sleeve, the coating may be partially removed to expose the metal layer (conductive layer).

[0095] like Figure 16A As shown, the strip 614 includes a conductive layer 614d and an insulating layer 614c covering the conductive layer 614d. For example, the conductive layer 614d is the base layer of the strip 614. The conductive layer 614d includes an exposed portion 614cc not covered by the insulating layer 614c, such that the conductive layer 614d is exposed to the outer surface of the strip 614. The brush 660 contacts the exposed portion 614cc, thereby releasing the charge of the heating unit 61 to the ground through the above-described grounding structure.

[0096] Figure 16B The illustration shows the state where the sheet S is located at the clamping part np1 and the toner image is fixed by the fixing unit 6. Figure 16BThe illustration shows the case where the toner image I formed on the sheet S has its maximum size in the generatrix direction (Y) of the belt 614. The portion of the belt 614 that is positioned concurrently with the toner image I in the generatrix direction (Y) of the belt 614 is referred to as the first belt portion 614I. At least a portion of the exposed portion 614cc is located outside the first belt portion 614I in the generatrix direction of the belt 614. Similarly, at least a portion of the brush 660 is located outside the first belt portion 614I in the generatrix direction of the belt 614. Compared to a configuration where the exposed portion 614cc is positioned concurrently with the first belt portion 614I in the generatrix direction of the belt 614, this configuration of the exposed portion 614cc reduces the impact on fixing quality.

[0097] As described above, the first embodiment, the first modified embodiment, and the second modified embodiment have been described. In this embodiment, the brush body 660a is made of conductive resin. However, this is not mandatory. Any material, such as a brush made of fine metal wire, a weak torsional helical spring, or a thin metal foil, can be used, as long as the material is conductive and can achieve stable contact with the strip 614 with a weak force that does not damage the strip 614.

[0098] According to this disclosure, a new type of fixing device that improves upon conventional technology is provided.

[0099] Although this disclosure has been described with reference to embodiments, it should be understood that this disclosure is not limited to the disclosed embodiments. The appended claims should be interpreted in the broadest possible sense to cover all such modifications and equivalent structures and functions.

Claims

1. A fixing device configured to be mounted in an image forming apparatus and fix toner onto recording material, the image forming apparatus including a main conductor portion capable of being electrically grounded, the fixing device comprising: A heating unit, the heating unit comprising an annular belt and a heater disposed inside the belt for heating the belt; A pressure roller, configured to form a clamping portion together with the heater via the belt; A pressure arm configured to press the heating unit against the pressure roller; A pressure spring configured to bias the pressure arm to press the heating unit against the pressure roller, the pressure spring being conductive; A frame, configured to support the heating unit and made of resin; A brush member configured to contact the strip and having electrical conductivity; A first conductor portion is configured to contact the brush member and the pressure spring, and is electrically connected to the brush member and the pressure spring; as well as The second conductor portion is configured to contact the pressure spring and the main conductor portion, and is electrically connected to the pressure spring and the main conductor portion.

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

3. The fixing device according to claim 1, in, The strip includes a conductive layer and an insulating layer covering the conductive layer. The conductive layer has an exposed portion that is not covered by the insulating layer, so as to be exposed to the outside of the strip; The brush component is in contact with the exposed portion of the conductive layer. The clamping part is formed by a pressure roller, a heater, and a belt. Wherein, when the recording material is located at the clamping portion and the toner image formed on the recording material has its maximum size in the generatrix direction of the tape, the portion of the tape located at the same position as the toner image in the generatrix direction is the first portion of the tape, and At least a portion of the exposed portion is located outside the first portion of the belt in the direction of the busbar.

4. The fixing device according to claim 1, wherein the fixing device further comprises: A camshaft, which is rotatably supported by the frame; as well as A cam, supported by the camshaft and configured to rotate with the camshaft to change the pressing force of the pressure arm on the pressure roller.

5. The fixing device according to claim 4, wherein, When viewed in the vertical direction, the first conductor portion has an overlapping portion that overlaps with the camshaft, the overlapping portion being located below the camshaft.

6. The fixing device according to claim 4, further comprising a second frame made of resin, wherein: The second frame is configured to support the camshaft when the first frame is in use. The first frame is made of resin, and The pressure spring and the brush component are conductive.

7. The fixing apparatus according to claim 6, wherein, The first conductor portion is supported by the second frame.

8. The fixing device according to claim 1, in, 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 spring.

9. The fixing device according to claim 4, in, The first conductor portion includes a first spring. The frame supports the camshaft and includes a shaft support portion extending in a vertical direction. The clamping part is formed by a pressure roller, a heater, and a belt. Wherein, when the direction in which the recording material is conveyed at the clamping part is defined as the recording material conveying direction, the downstream end of the shaft support part in the recording material conveying direction is the downstream support end, and The downstream support end is located between the camshaft and the first spring in the recording material conveying direction.

10. The fixing apparatus according to claim 9, wherein, The downstream end of the shaft support restricts the movement of the first spring in the direction approaching the camshaft.

11. The fixing device according to claim 3, wherein, The conductive layer is the base layer of the strip.

12. The fixing device according to claim 1, in, The second conductor portion includes a torsion helical spring, and The torsion helical spring contacts the main conductor portion.

13. The fixing device according to claim 1, wherein, The main conductor portion is an electrode.

14. The fixing device according to claim 4, wherein, The first conductor portion includes a camshaft contact portion that contacts the camshaft.

15. The fixing device according to claim 1, in, The clamping part is formed by a pressure roller, a heater, and a belt. The direction in which the heating unit delivers the recording material located at the clamping part is the recording material delivery direction. The frame includes an upper guide surface located downstream of the heating unit in the recording material delivery direction, and The upper guide surface guides the upper surface of the recording material being transported along the recording material transport direction.

16. A fixing device attached to the main body of an image forming apparatus and fixing toner onto recording material, the image forming apparatus including a main conductor portion capable of being electrically grounded, the fixing device comprising: A heating unit, the heating unit comprising an annular belt and a heater for heating the interior of the belt; A pressure roller, configured to form a clamping portion together with the heater via the belt; A conductive pressure arm, configured to press the heating unit against the pressure roller; A conductive pressure spring, the pressure spring being configured to contact the conductive pressure arm and bias the conductive pressure arm toward the direction of pressing the heating unit; A frame made of resin and configured to support the heating unit; A brush member configured to contact the strip and having electrical conductivity; An intermediate conductor portion is configured to contact both the brush member and the conductive pressure arm to electrically connect the brush member and the conductive pressure arm; as well as A conductor portion is configured to contact both the pressure spring and the main conductor portion to electrically connect the pressure spring and the main conductor portion.

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