Fixing device

Abstract

The objective is to provide a new type of fixing device that builds upon conventional technology. [Solution] A fixing device comprising: a heating unit comprising a belt and a heater for heating the belt; a pressure roller that forms a nip portion together with the heater via the belt; a conductive pressure spring that biases a pressure arm so that the heating unit is pressed against the pressure roller; a conductive bearing that supports the rotation axis of the pressure roller; a resin frame that supports the bearing; a conductive brush member that contacts the belt; a first conductive part that contacts both the brush member and the pressure spring so as to electrically connect the brush member and the pressure spring; a second conductive part that contacts both the pressure spring and the main conductive part so as to electrically connect the pressure spring and the main conductive part; and a third conductive part that contacts both the first conductive part and the bearing so as to electrically connect the rotation axis and the main conductive part.

Description

Technical Field

[0001] The present invention relates to an electrophotographic image forming apparatus.

Background Art

[0002] The fixing device described in Patent Document 1 includes a heating unit having a heater that heats the inner surface of a belt, and a pressure roller that forms a nip portion together with the heater via the belt, and fixes the toner on the recording material.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present invention is to provide a new form of fixing device that develops on the basis of the conventional technology.

Means for Solving the Problems

[0005] One aspect of the present invention is as follows.

[0006] In a fixing device mounted on a device main body of an image forming apparatus and having a main body conductor portion that can be electrically grounded, for fixing toner on a recording material, a heating unit including an endless belt and a heater provided on the side of the inner surface of the belt for heating the belt; a pressure roller that forms a nip portion together with the heater via the belt; a pressure arm for pressing the heating unit against the pressure roller; a conductive pressure spring that biases the pressure arm so that the heating unit is pressed against the pressure roller; A conductive bearing supporting the rotation axis of the pressure roller, A resin frame supporting the aforementioned bearing, A conductive brush member that contacts the belt, A first conductive portion that contacts both the brush member and the pressure spring so as to electrically connect the brush member and the pressure spring, A second conductor portion that contacts both the pressure spring and the main body conductor portion so as to electrically connect the pressure spring and the main body conductor portion, A third conductor portion that contacts both the first conductor portion and the bearing so as to electrically connect the rotating shaft and the main body conductor portion, A fixing device characterized by comprising: [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a new form of fixing device that is an advancement of the conventional technology. [Brief explanation of the drawing]

[0008] [Figure 1] Perspective views (a, b) of the fixing device according to Example 1. [Figure 2] Cross-sectional view of the fixing device according to Example 1. [Figure 3] Cross-sectional view of the fixing device according to Example 1. [Figure 4] Cross-sectional view of the fixing device according to Example 1. [Figure 5] An exploded perspective view of the fixing device according to Example 1. [Figure 6] Perspective views (a, b) of the fixing device according to Example 1. [Figure 7] Top view of the fixing device according to Example 1. [Figure 8] A perspective view of the fixing device according to Example 1. [Figure 9] Cross-sectional view of the fixing device according to Example 1. [Figure 10] Front view and top view (a, b) of the contact spring according to Example 1. [Figure 11] Front view and cross-sectional view (a, b, c, d) of the fixing device according to Example 1. [Figure 12] Cross-sectional views (a, b) of the fixing device according to Embodiment 1. [Figure 13] Exploded perspective view of the fixing device according to Embodiment 1. [Figure 14] Plan view of the fixing device according to Embodiment 1. [Figure 15] Plan view of the fixing device according to Embodiment 1. [Figure 16] Plan view of the fixing device according to Embodiment 1. [Figure 17] Plan view of the fixing device according to Embodiment 1. [Figure 18] Perspective view of the fixing device according to Embodiment 1. [Figure 19] Perspective view of the fixing device according to Embodiment 1. [Figure 20] Plan view of the fixing device according to Embodiment 2. [Figure 21] Plan view of the fixing device according to Embodiment 2. [Figure 22] Plan view of the fixing device according to Embodiment 2. [Figure 23] Plan view of the fixing device according to Embodiment 3. [Figure 24] Plan view of the fixing device according to Embodiment 4.

Mode for Carrying Out the Invention

[0009] [Embodiment 1] Hereinafter, embodiments of the present invention will be described based on the drawings. Note that the dimensions, materials, shapes, relative arrangements, etc. of the components described in the following embodiments may be appropriately changed according to the configuration of the device to which the present invention is applied and various conditions. Therefore, unless specifically stated, the scope of the present invention is not limited to this embodiment.

[0010] Figure 2 is a cross-sectional view of an electrophotographic image forming apparatus 1 to which the fuser of this embodiment is applied. In the following description, as shown in Figure 2, the vertical direction when the image forming apparatus 1 is installed on a horizontal plane is referred to as the Z direction. The direction intersecting the Z direction is referred to as the Y direction. The Y direction is parallel to the rotation axis direction of the pressure arm 652, which will be described later. The direction intersecting both the Z and Y directions is referred to as the X direction. The X direction is parallel to the direction in which the heating unit 61, which will be described later, transports the recording material located in the nip section. The X and Y directions are preferably horizontal. Furthermore, the X, Y, and Z directions are preferably orthogonal to each other. In addition, as necessary, the directions of the arrows X, Y, and Z shown in each drawing will be referred to as the +X side, +Y side, and +Z side, respectively, and the opposite sides will be referred to as the -X side, -Y side, and -Z side, respectively. In the following description, the direction in which the recording material is transported in the nip section np1, which will be described later, will be referred to as the recording material transport direction (+X direction). Furthermore, the +X direction is the mounting direction in which the fixing device 6, described later, is attached to the main body 2 of the device, and in the following explanation, it may be simply referred to as the "mounting direction". Also, the rotation axis direction of the pressure arm 652, described later, is called the axial direction. In the axial direction, the direction from the heating unit 61, described later, toward the electrical contact 668b1 is called the first axial direction (+Y direction). In the axial direction, the direction opposite to the first axial direction is called the second axial direction (-Y direction). The Y direction is also the longitudinal direction of the heating unit 61. Also, the Y direction is the busbar direction of the belt 614. Also, the longitudinal direction of the heating unit 61, the direction from the contact spring 668 toward the longitudinal center of the heating unit is called the first direction (-Y direction).

[0011] [Configuration of the image forming apparatus] The configuration of the image forming apparatus 1 will be explained using Figure 2. The image forming apparatus 1 comprises an apparatus body 2, a process cartridge 10, and a fixing device 6. The process cartridge 10 is detachably attached to the apparatus body 2. The fixing device 6 is detachably attached to the apparatus body 2. It can also be said that the fixing device 6 is mounted on the apparatus body 2. Note that the fixing device 6 may be attached in a non-detachable manner.

[0012] The main unit 2 of the apparatus comprises a paper feed tray 3, a sheet feeding unit 4, a transport path P, a transfer roller 51, a sheet discharge unit 7, a paper output tray 8, a laser scanner 9, and an opening / closing door 21. The process cartridge 10 comprises a photosensitive drum 11 and a developing roller 12 as a developer carrier. The process cartridge 10 also contains developer inside. The opening / closing door 21 is supported so as to be rotatable around a pivot axis 21a and is configured to move between a closed position that closes the opening 2a and an open position that opens the opening 2a. When the opening / closing door 21 is in the open position with the opening 2a open, the process cartridge 10 can be attached to and detached from the main unit 2 through the opening 2a.

[0013] The sheet feeding unit 4 consists of a paper feed roller 41, a separation roller 42, a separation pad 42a, and a transport roller pair 43. Based on the print start signal, the sheet S stored in the paper feed tray 3 is sent to the transport path P by the sheet feeding unit 4 and transported towards the transfer roller 51 via the registration roller pair 44.

[0014] When the sheet S is transported to a predetermined position, an image formation start signal is issued, and the image formation process begins. The photosensitive drum 11, which is rotated by a drive source (motor) (not shown), is uniformly charged to a predetermined potential by a charging means (not shown). The surface of the charged photosensitive drum 11 is exposed by a laser scanner 9 based on image information, and an electrostatic image is formed in which the charge of the exposed area is removed. The toner in the process cartridge 10 is carried on the developing roller 12 and supplied to the photosensitive drum 11 according to the electrostatic latent image, developing the latent image. As a result, the latent image is made visible on the photosensitive drum 11 as a toner image.

[0015] The transfer roller 51 is positioned opposite the photosensitive drum 11 of the process cartridge 10. When the sheet S, conveyed by the registration roller pair 44, passes through the nip between the photosensitive drum 11 and the transfer roller 51, a voltage is applied to the transfer roller 51 from the main body 2 of the device, and the toner image on the photosensitive drum 11 is transferred to the sheet S as an unfixed image. Subsequently, the sheet S with the transferred toner image is conveyed to a fixing device 6 equipped with a heating unit 61 and a pressurizing rotating body 62. The fixing device 6 is a fixing device that fixes toner (developer) to the recording material. When the sheet S passes through the nip of the heating unit 61 and the pressurizing rotating body 62, the unfixed image transferred on the sheet S is heated and pressurized and fixed to the surface of the sheet S. The sheet S with the fixed toner image is discharged to the output tray 8 via the sheet discharge unit 7.

[0016] [Fuser configuration] Next, the configuration of the fuser will be described. Figure 3 is a plan view of the fuser device 6. As shown in Figure 3, the heating unit 61 comprises a heater 611, a holder 612, a stay 613, and a belt 614. The heater 611 is provided on the inner surface side of the belt 614 and heats the belt 614. The heater 611 extends in the direction of the generatrix (Y direction) of the belt 614, and the shape of the heater 611 is flat. 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 holder 612.

[0017] The holder 612 is made of a heat-resistant resin such as PPS or 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 that supports the heater 611. The support surface 612b1 of the support wall 612b is in contact with the first surface 611a of the heater 611. The stay 613 is a member that supports the holder 612, and is formed by bending a plate material with greater rigidity than the holder 612, for example, a steel plate with a thickness of 1.6 mm, into a roughly U-shape.

[0018] The belt 614 is an endless belt that is heat-resistant and flexible, and is composed of, for example, a metal sleeve such as stainless steel coated with fluororesin, or a laminate of polyimide resin, silicone rubber, fluororesin, etc. A heater 611, a holder 612, and a stay 613 are arranged inside the belt 614, and the belt 614 is configured to rotate around these. The inner circumferential surface 614a of the belt 614 is in contact with the second surface 611b of the heater 611.

[0019] The pressurizing rotating body 62 (pressurizing roller) has a metal shaft 62a and a roller 62b made of an elastic material that covers the shaft 62a, and is pressed against the heater 611 via a belt 614. The pressurizing rotating body 62 sandwiches the belt 614 between itself and the heater 611, forming a nip portion np1 for nipping, heating, and pressurizing the sheet S. In other words, the pressurizing rotating body 62 (pressurizing roller) can be said to form a nip portion np1 together with the heater 611 via the belt 614. That is, the pressurizing rotating body 62 heats and pressurizes the sheet S together with the heater 611 at the nip portion np1.

[0020] The pressurized rotating body 62 is configured to rotate when a driving force is transmitted from a drive source provided by the image forming apparatus 1. As the pressurized rotating body 62 rotates, the belt 614 rotates in response. The sheet S on which the toner image has been transferred is transported between the pressurized rotating body 62 and the heated belt 614, thereby thermally fixing the toner image.

[0021] Next, the frame configuration of the fixing device 6 will be described using Figure 4. Figure 4 is a plan view of the fixing device 6. The fixing device 6 has an upper frame 64 and a lower frame 63. The lower frame 63 can also be called the first frame and the upper frame 64 can be called the second frame. The lower frame 63 is the frame that supports the heating unit 61 and the pressurizing rotating body 62. The upper frame 64 (first frame) is located above the lower frame 63 (second frame) and covers the heating unit 61. The lower frame 63 and the upper frame 64 are resin components formed by non-conductive molded 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). The upper guide surface 64a guides the side (upper surface) of the sheet S that is transported in the recording material transport direction that faces the heating unit 61. The lower frame 63 has a lower guide surface 64a located downstream of the heating unit 61 in the recording material transport direction. The lower guide surface 64a guides the lower surface of the sheet S as it is transported in the direction of transporting the recording material.

[0022] Next, the configuration of the lower frame 63 that supports the pressurized rotating body 62 will be described using Figure 5. Figure 5 is an exploded perspective view of the fixing device 6. The lower frame 63 has rails 63b at its ends in the first axial direction and the second axial direction, respectively. The rails 63b extend vertically and support the holder 612 so that it can move vertically. The two rails 63b face each other in the axial direction. The rails 63b engage with grooves 617a1 and 617b1 provided in the transmission members 617a and 617b, respectively.

[0023] The fixing device 6 includes a bearing 62c. The end of the shaft 62a in the first axial direction and the end in the 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 electrically conductive. In this configuration, bearings 62c and 62d have protrusions and the lower frame 63 has recesses 63d1 and 63d2, but the relationship between the protrusions and recesses may be reversed. Also, the means for fixing bearings 62c and 62d to the lower frame 63 does not have to be of a protrusion-recess shape.

[0024] [Configuration of the pressurizing mechanism] Next, the configuration of the pressure mechanism of the fixing device 6 will be described. Figure 11(a) is a front view of the fixing device 6. Figures 11(b) to (d) are cross-sectional views of Figure 11(a), respectively.

[0025] As shown in Figure 11, the fixing device 6 has a pressurizing mechanism 65 that presses the heating unit 61 against the pressurizing rotating body 62. The pressurizing mechanism 65 is provided at both the end of the lower frame 63 in the first axial direction and the end in the second axial direction. In other words, it can be said that the pressurizing mechanism 65 is supported by the lower frame 63. The structure of the pressurizing mechanism 65 provided on the end of the lower frame 63 in the first axial direction and the pressurizing mechanism 65 provided on the end of the lower frame 63 in the second axial direction are substantially the same. Therefore, the explanation of the pressurizing mechanism 65 provided on the first axial direction side also applies to the pressurizing mechanism 65 provided on the second axial direction side, so the explanation is omitted.

[0026] The pressurizing mechanism 65 includes a transmission member 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 rotatably supported around the central axis X1 of the support portion 64d. The support portion 64d is a substantially cylindrical projection.

[0027] The pressure arm 652 presses the transmission member 651 from above, moving the transmission member 651 downward. This causes the transmission member 651 to press the stay 613 downward. The transmission member 651 presses the stay 613, moving the stay 613 downward. As the stay 613 moves downward, the heating unit 61, which includes the stay 613, is pressed toward the pressure rotating body 62. The pressure spring 653 is a conductive tension coil spring that biases the pressure arm 652 so that the heating unit 61 is pressed toward the pressure rotating body 62. The pressure spring 653 engages with the lower frame 63 and the pressure arm 652. The biasing of the pressure arm 652 by the pressure spring 653 causes the pressure arm 652 to move the transmission member 651 downward. That is, the pressure arm 652 presses the heating unit 61 toward the pressure rotating body 62 (pressure roller).

[0028] [Configuration of the pressure release mechanism] Next, the configuration of the pressure release mechanism provided in the fixing device 6 will be described using Figures 12 and 13. Figure 12 is a cross-sectional view of the fixing device 6. Figure 12(a) shows the pressurized state when the pressure release mechanism 67 is pressurized. Figure 12(b) shows the depressurized state when the pressure release mechanism 67 has released the pressure. Figure 13 is an exploded perspective view of the upper frame 64, lower frame 63 and camshaft 671, with some parts such as the heating unit 61 and pressurizing rotating body 62 omitted. The pressure release mechanism 67 is a nip pressure release mechanism that changes the nip pressure in the nip section np1 between the heating unit 61 and the pressurizing rotating body 62. The pressure release mechanism 67 includes a camshaft 671 and a cam 672.

[0029] As shown in Figure 12, the camshaft 671 is rotatable about axis X2. The camshaft 671 extends axially and is made of conductive metal. As shown in Figure 13, cams 672 are fixed (supported) to the first axial end and the second axial end of the camshaft 671, respectively. The cams 672 are supported so as to rotate together with the camshaft 671. The cams 672 are provided on the first axial end side and the second axial end side of the lower frame 63, respectively. The structure of the cam 672 provided on the first axial end side and the cam 672 provided on the second axial end side of the lower frame 63 are substantially the same.

[0030] The cam 672 presses against the pressurizing arm 652 against the biasing force of the pressurizing spring 653. That is, the cam 672 rotates, changing the pressure exerted by the pressurizing arm 652 on the pressurizing rotating body 62 of the heating unit 61. The cam 672 is rotatable between the pressurizing position shown in Figure 12(a) and the release position shown in Figure 12(b).

[0031] To release the pressurized state, the camshaft 671 is rotated, causing the cam 672 to rotate. When the cam 672 rotates, the pressurizing 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 stay 613 is pressed against the transmission member 651. As a result, the pressure pressing the heating unit 61 toward the pressurizing rotating body 62 decreases.

[0032] Next, the support configuration of the camshaft 671 will be described using Figure 13. 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. In other words, the support wall 63l can also be called a shaft support portion that supports the camshaft 671. The support walls 63l are provided on the end side in the first axial direction of the lower frame 63 and on the end side in the second axial direction of the lower frame 63. In addition, substantially the same hole 631h is provided in each support wall 63l.

[0033] The upper frame 64 has a support wall 64l that rotatably supports the camshaft 671. The support wall 64l extends vertically. The support wall 64l has a hole 641h that rotatably supports the camshaft 671. The camshaft 671 passes through the hole 641h. The support wall 64l is provided on the end side of the upper frame 64 in the first axial direction and on the end side of the lower frame 63 in the second axial direction. In addition, substantially the same hole 641h is provided in each support wall 64l.

[0034] [Grounding configuration of the fuser] Next, the grounding configuration of the fixing device 6 will be described. In this embodiment, the fixing device 6 is equipped with a grounding configuration for removing static electricity generated in the heating unit 61 of the fixing device 6. Static electricity generated in the fixing device 6 flows to the main body of the device 2 via the static electricity remover 66.

[0035] <Static electricity remover> The configuration of the electrostatic discharger 66 will be explained using Figures 1, 6 to 9. Figures 1(a) and 1(b) are perspective views of the fixing device 6. Figure 6(a) is a perspective view of the fixing device 6. Figure 6(b) is a perspective view of the fixing device 6 when the cover 661 shown in Figure 6(a) is omitted. Figure 7 is a top view of the fixing device 6. Figure 8 is a perspective view of the fixing device 6. Figure 9 is a cross-sectional view of the fixing device 6.

[0036] As shown in Figure 6(a), an electrostatic discharger 66 is attached to the upper frame 64 to remove static electricity generated in the fixing device 6. The electrostatic discharger 66 is located downstream of the midpoint 614m of the belt 614 in the first axial direction.

[0037] As shown in Figures 6 to 9, the electrostatic discharger 66 comprises a brush 660, a first conductive plate 662, a resistive member 663, a second conductive plate 664, a cover 661, screws 665 and 666, and a first conductive spring 667.

[0038] The brush 660 is in contact with the heating unit 61 and the first conductive plate 662. The first conductive plate 662 is in contact with the resistance member 663. The second conductive plate 664 is in contact with the first conductive spring 667. Furthermore, the brush 660, the first conductive plate 662, the resistance member 663, and the second conductive plate 664 are all conductive. Therefore, static electricity generated in the heating unit 61 is transmitted from the brush 660 to the first conductive spring 667.

[0039] The cover 661 is a cover that covers the brush 660, the first conductive plate 662, and the second conductive plate 664 from above. As shown in Figures 6(a) and 6(b), screws 665 secure the first conductive plate 662 to the upper frame 64 together with the cover 661. Screws 666 also secure the second conductive plate 664 to the upper frame 64 together with the cover 661.

[0040] The configuration of the brush 660 (brush member) will now be described. As shown in Figure 8, the brush 660 is fixed inside the upper frame 64. As shown in Figure 9, the brush 660 is a conductive member that contacts the belt 614 from above. The brush 660 comprises a brush body 660a and a base plate 660b. The brush body 660a is made of a conductive resin. The base plate 660b is made of SUS, a metal, and is conductive. The brush body 660a is in contact with the surface 614b (conductive layer) of the belt 614, and the brush body 660a and the belt 614 are electrically connected. That is, the brush 660 and the heating unit 61 are electrically connected. In this embodiment, the brush body 660a is in contact with the surface 614b of the belt 614, but a conductive member may be placed between the brush body 660a and the belt 614 to make the brush body 660a and the belt 614 electrically connected. The base plate 660b is a plate fixed to the brush body 660a and the upper frame 64. That is, the brush body 660a is fixed to the upper frame 64 via the base plate 660b. As shown in Figure 8, the base plate 660b is in contact with the contact portion 662b of the first conductive plate 662, which will be described later. That is, the base plate 660b and the first conductive plate 662 are electrically connected. As shown in Figure 7, the brush body 660a is in contact with the transmission member 617a. More specifically, when viewed in the vertical direction (Z direction), the brush body 660a overlaps with the transmission member 617a in the first axial direction, at least in part.

[0041] Next, the configuration of the first conductive plate 662 will be described. As shown in Figure 7, the first conductive plate 662 is a conductive member located upstream of the brush 660 in the first axial direction. As shown in Figure 6, a first hole 662d is formed in a part of the first conductive plate 662, and the screw 665 passes through the first hole 662d. Therefore, the first conductive plate 662 is fixed (supported) to the upper frame 64 by the screw 665. As shown in Figure 7, the first conductive plate 662 has contact portions 662a, 662b, and 662c. Contact portion 662a is in contact with the resistor member 663, which will be described later. That is, the first conductive plate 662 is electrically connected to the resistor 663. As shown in Figures 7 and 8, contact portion 662b is in contact with the base plate 660b. That is, contact portion 662b and the base plate 660b are electrically connected. Therefore, since the first conductive plate 662 is electrically connected to the brush 660 and the resistive member 663, static electricity can be passed from the brush 660 towards the resistive member 663.

[0042] Next, the configuration of the resistor 663 will be described. The grounding configuration in this embodiment includes the resistor 663. By slowly grounding the current through the resistor 663, it is possible to prevent the protective layer formed on the surface of the heater 611 from being damaged. As shown in Figure 7, the resistor 663, which has a predetermined electrical resistance, is pressed toward the upper frame 64 by the contact portion 662a of the first conductive plate 662 and the contact 664a of the second conductive plate 664, and is fixed to the upper frame 64.

[0043] Resistor 663 is in contact with contact portion 662a, and resistor 663 and the first conductive plate 662 are electrically connected. Also, resistor 663 is in contact with contact 664a of the second conductive plate 664, which will be described later, and resistor 663 and the second conductive plate 664 are electrically connected. Therefore, since resistor 663 is electrically connected to both the first conductive plate 662 and the second conductive plate 664, static electricity can be passed from the first conductive plate 662 to the second conductive plate 664.

[0044] Next, the configuration of the second conductive plate 664 will be described. As shown in Figure 6, the second conductive plate 664 has a second hole 664d formed therein, and the screw 666 passes through the second hole 664d. Therefore, the second conductive plate 664 is fixed to the upper frame 64 by the screw 665.

[0045] As shown in Figure 7, the second conductive plate 664 is a conductive material and includes contact portions 664a, 664b, and 664c. Contact portion 664a is in contact with the resistor 663. That is, the resistor 663 and the second conductive plate 664 are electrically connected. A third hole 664h is formed in contact portion 664b. The hook 667a of the first conductive spring 667, which will be described later, passes through the third hole and engages with the contact portion 664b. Contact portion 664b is in contact with the hook 667a of the first conductive spring 667, which will be described later. That is, the second conductive plate 664 and the first conductive spring 667 are electrically connected. Therefore, 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.

[0046] As shown in Figure 7, when viewed vertically, 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 positioning the second conductive plate 664 below the camshaft 671 in this way, the second conductive plate 664 is less likely to be interfered with by the rotational movement of the camshaft 671 compared to a configuration in which the second conductive plate 664 is positioned above the camshaft 671.

[0047] Furthermore, as shown in Figures 1 and 7, the contact portion 664c is in contact with the camshaft 671 from above. The contact portion 664c can be called the camshaft contact portion. With this configuration, the charge accumulated on the camshaft 671 can escape to the main conductor portion 2A, which will be described later, via the second conductive plate 664 and the pressure spring 653. In other words, the second conductive plate 664 in this embodiment can not only release the charge generated in the heating unit 61, but also release the charge accumulated on the camshaft 671.

[0048] Next, the configuration of the first conductive spring 667 will be described. The first conductive spring 667 is a conductive component. As shown in Figure 6, the first conductive spring 667 has a main spring 667c, a hook 667a, and a hook 667b.

[0049] 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 via third hole 664h. Hook 667b engages with upper hook 653a of the pressure spring 653, which will be described later. That is, the first conductive spring 667 contacts and conducts electricity with the second conductive plate 664 and the pressure spring 653, respectively. The main spring 667c extends from hook 667a in the first axial direction and is connected to hook 667b. That is, the first conductive spring 667 (first spring) extends in the direction of the rotation axis of the pressure arm 652 and is electrically connected to the pressure spring 653.

[0050] Next, the positional relationship between the main spring 667c and the frame will be explained using Figure 6(a). A groove shape 641c is formed in the support wall 64l of the upper frame 64. The groove shape 641c is designed to allow the main spring 667c to pass through the support wall 63l from upstream to downstream in the first axial direction. The first conductive spring 667 passes through the groove shape 641c and extends in the first axial direction.

[0051] The end of the support wall 63l of the lower frame 63 in the recording material transport direction is called the downstream support end 631e. As shown in Figure 6(a), in the recording material transport direction, the downstream support end 631e is located between the camshaft 671 and the first conductive spring (first spring). The downstream support end 631e contacts the first conductive spring 667, guiding it to restrict its movement toward the camshaft 671. This configuration reduces the possibility of the first conductive spring 667 being interfered with by the rotation of the camshaft 671. In this embodiment, the first conductive spring 667 is configured to contact the downstream support end 631e, but the first conductive spring 667 may be positioned further downstream in the recording material transport direction than the downstream support end 631, so that the first conductive spring 667 and the downstream support end 631e do not come into contact.

[0052] Next, the electrical connection of the pressure spring 653 will be explained using Figures 1, 7, and 12. The pressure spring 653 comprises 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). In other words, the pressure spring 653 can be said to extend downward from the upper hook 653a toward 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, which will be described later, engages with the lower hook 653b. Therefore, the pressure spring 653 is in contact with and electrically connected to the first conductive spring 667 and the second conductive spring 669, respectively.

[0053] As shown in Figure 12, the pressure arm 652 has a groove, which is an arm engagement portion 652a. The upper hook 653a is supported by engaging with the arm engagement portion 652a. That is, the pressure spring 653 is in contact with and supported by the pressure arm 652. The lower frame 63 also has a groove, which is a frame engagement portion 63e1. The lower hook 653b is supported by engaging with the frame engagement portion 63e1.

[0054] The conductivity configuration of the second conductivity spring 669 will be explained using Figure 1. The second conductivity spring 669 has a hook 669a, a hook 669b, and a main spring 669c. One end of the second conductivity spring 669 is the hook 669a, and the other end is the hook 669b. The main spring 669c is connected to the hooks 669a and 669b. The second conductivity spring 669 extends from the hook 669a toward the hook 669b in the direction of recording material transport. The hook 669a engages with the contact spring 668, which will be described later. Also, as mentioned above, the hook 669b engages with the lower hook 653b. Therefore, the second conductivity spring 669 is in contact with and electrically connected to the compression spring 653 and the contact spring 668, respectively.

[0055] Next, the electrical configuration of the contact spring 668 will be described using Figures 1 and 10. Figure 10(a) is a front view of the contact spring 668. Figure 10(b) is a top view of the contact spring 668. 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 upstream in the mounting direction from one end of the coil portion 668a, and a second arm 668c extending downstream in the mounting direction from the other end. The coil portion 668a is supported by the lower frame 63 by wrapping around a boss 63e provided on the lower frame 63. That is, the boss 63e is inserted into the coil portion 668a.

[0056] The first arm 668b has a spring attachment portion 668b2, an extension portion 668b3, a first arm tip portion 668b4, and a bent portion 668b5, and has an electrical contact 668b1 at its tip that contacts the main body conductor portion 2A of the device body 2, which will be described later. The first arm tip portion 668b4 is the tip of the first arm. The electrical contact 668b1 can also be said to be the tip of the first arm. When the electrical contact 668b1 contacts the main body conductor portion 2A, static electricity flows from the fixing device 6 towards the device body 2.

[0057] The spring attachment portion 668b2 extends from one end of the coil portion 668a in the axial direction of the coil portion 668a. The extension portion 668b3 bends from the spring attachment portion 668b2 and extends in a direction intersecting the axial direction of the coil portion 668a. The tip portion 668b4 of the first arm bends from the extension portion 668b3 at the bent portion 668b5 and extends in a direction perpendicular to the axial direction of the coil portion 668a. The electrical contact 668b1 is the tip of the first arm 668b and consists of the shape of a metal wire as it is after being cut, without any rounding or other processing, and has a sharp edge. In Figure 14, the metal wire is depicted as being neatly cut at a right angle, but it may have an irregular shape, for example, a shape that is a transfer of the shape of the cutting tool blade.

[0058] The second arm 668c has a second extension 668c1, a third extension 668c2, a retaining portion 668c3, and a pressed 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 pressed portion 668c4 is the portion that bends from the second extension 668c1 to the third extension 668c2. The third extension 668c2 extends in a direction perpendicular to the axial direction of the coil portion 668a and in a direction different from that of the second extension 668c1. The retaining portion 668c3 extends from the end of the third extension 668c2 furthest from the coil portion 668a in the axial direction of the coil portion 668a.

[0059] One end 669a of the second conductive spring 669 engages with the spring attachment portion 668b2. The second conductive spring 669 is a tension spring. The other end 669b of the second conductive spring 669 engages with the lower hook 653b of the compression spring 653. As a result, as shown in Figure 1, the contact spring 668 is biased by the second conductive spring 669 to rotate around the axis B of the boss 63e (in the direction of arrow C).

[0060] When the fixing device 6 is not mounted on the device body 2, the bending portion of the first arm 668b is in contact with the abutment surface 63f provided on the lower frame 63 due to the biasing force of the second conductive spring 669, and its orientation is fixed. The lower frame 63 also has a first protective wall 63h located on one side of the first arm tip 668b4 in the axial direction b of the coil portion 668a, and a second protective wall 63k located on the other side of the first arm tip 668b4. That is, the first arm tip 668b4 is located in the gap between the first protective wall 63h and the second protective wall 63k. At this time, the electrical contact 668b1 does not protrude from the first protective wall 63h and the second protective wall 63k, or protrudes only slightly. As a result, when the fixing device 6 is not mounted on the device body 2, the electrical contact 668b1 is protected by the first protective wall 63h and the second protective wall 63k, and is less likely to get caught on other objects.

[0061] On the other hand, when the fixing device 6 is not attached to the device body 2, the pressed portion 668c4 is bent so as to protrude from the lower frame 63. The lower frame 63 has a slit 63g and a retaining wall 63n on the downstream side of the boss 63e in the direction opposite to the recording material transport direction. The slit 63g extends in a direction perpendicular to the axis of the boss 63e. More specifically, the slit 63g extends in the recording material transport direction. The retaining wall 63n is positioned adjacent to the slit 63g. The third extension portion 668c2 of the second arm 668c enters the slit 63g. The retaining portion 668c3 is located upstream of the retaining wall 63n in the first axial direction and faces the retaining wall 63n. As a result, when the second conductive spring 669 rotates in the direction of arrow c, which is the direction in which the pressed portion 668c4 protrudes, the retaining portion 668c3 comes into contact with the retaining wall 63n.

[0062] Next, the conductive configuration of the main body 2 of the device will be explained using Figure 17. Figure 17 is a top view of the fixing device 6, showing the fixing device 6 mounted on the main body 2 of the device. The main body 2 of the device has a conductive main body conductor portion 2A. In this embodiment, the main body conductor portion 2A is an electrode. The contact spring 668 is located closer to the longitudinal center of the heating unit 61 than the main body conductor portion 2A.

[0063] The main conductor portion 2A is a metal plate that also serves as the frame of the device body 2. The main conductor portion 2A is configured to be electrically groundable. The main conductor portion 2A includes a contact surface 2As that forms the end on the first direction side of the main conductor portion 2A and extends in the mounting direction (+X direction). The contact surface 2As is in contact with the electrical contact 668b1 and is electrically conductive. Therefore, the main conductor portion 2A is capable of discharging static electricity flowing from the electrical contact 668b1 to the ground.

[0064] The grounding configuration of the fuser has been explained above. As previously stated, the brush body 660a is in contact with the surface 614b of the belt 614, and the brush body 660a and the belt 614 are electrically connected. The brush 660 is in contact with the first conductive plate 662 and is electrically connected. The resistor 663 is in contact with the second conductive plate 664 and is electrically connected. The second conductive plate 664 is in contact with the first conductive spring 667 and is electrically connected. The first conductive spring 667 is in contact with the pressure spring 653 and is electrically connected. The pressure spring 653 is in contact with the second conductive spring 669 and is electrically connected. The second conductive spring 669 is in contact with the contact spring 668 and is electrically connected. The electrical contact 668b1 of the contact spring 668 is in contact with the main body conductor portion 2A of the device body 2 and is electrically connected. The main conductor section 2A is configured to be electrically groundable.

[0065] Here, the first conductive plate 662, the resistor 663, and the second conductive plate 664 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, the resistor 663, the second conductive plate 664, and the first conductive spring 667 (first spring). The first conductor section 600a contacts the brush 660 (brush member) and the pressure spring 653, respectively, and provides electrical conductivity between the brush 660 (brush member) and the pressure spring 653.

[0066] The second conductive spring 669 and the contact spring 668 can be collectively referred to as the second conductor section 600b. In other words, the second conductor section 600b includes the second conductive spring 669 and the contact spring 668. The second conductor section 600b contacts the pressure spring 653 and the main conductor section 2A, and provides electrical conductivity between the pressure spring 653 and the main conductor section 2A.

[0067] Therefore, the charge generated in the heating unit 61 is grounded via the brush 660, the first conductor part 600a, and the second conductor part 600b. With this configuration, the charge accumulated in the heating unit 61 can be removed.

[0068] Furthermore, in the fixing device 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 part of the grounding configuration. However, as described above, by connecting the brush 660, the first conductor section 600a, and the second conductor section 600b to the main body conductor section 2A, it is possible to dissipate the charge generated in the heating unit 61.

[0069] Furthermore, in the fixing device 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. That is, it can be said that the upper frame 64 supports the first conductor portion 600a. It can also be said that the first conductor portion 600a is attached to the upper frame 64. It can also be said that the upper frame 64 guides the first conductor portion 600a. By supporting the first conductor portion 600a with the upper frame 64 in this way, the stability of the first conductor portion 600a against external forces can be improved.

[0070] Furthermore, as described above, the coil portion 668a is supported by the lower frame 63 by wrapping around the boss 63e provided on the lower frame 63. Also, the lower hook 653b is engaged with and supported by the frame engagement portion 63e1. Therefore, in the fixing device 6 of this embodiment, it can be said that the lower frame 63 supports the second conductor portion 600a. It can also be said that the second conductor portion 600b is attached to the lower frame 63.

[0071] [Attaching the fuser unit to the main unit] Next, the operation of the contact spring 668 during the mounting process in which the fixing device 6 is moved to the mounting position and attached to the device body 2 will be described. The fixing device 6 is attached to the mounting position by being moved in the mounting direction (+X direction) relative to the device body 2. Figure 14 is a top view showing the state before the fixing device 6 is attached to the device body 2. Figure 15 is a top view showing the state after the fixing device 6 has been further inserted into the device body 2 from Figure 14. Figure 16 is a top view showing the state after the fixing device 6 has been further inserted into the device body 2 from Figure 15. Figure 17 is a top view showing the state after the fixing device 6 has been further inserted into the device body 2 from Figure 16 and the fixing device 6 has been attached to the device body 2 in the mounting position.

[0072] As shown in Figure 14, the main body conductor portion 2A includes the main body upstream end 2Ae, which is the upstream end of the main body conductor portion 2A in the mounting direction. The main body upstream end 2Ae extends in the first direction (-Y direction). The end of the main body upstream end 2Ae on the first direction side is connected to the end of the contact surface 2As on the side opposite to the mounting direction (-X direction).

[0073] The position of the contact spring 668 before the fixing device 6 is installed will now be described. As shown in Figure 14, in the state before the fixing device 6 is installed, the electrical contact 668b1 and the pressed portion 668c4 are located upstream of the main body upstream end 2Ae in the installation direction. Also, in the first direction, the pressed portion 668c4 is located upstream of the contact surface 2As. Also, in the first direction, a part of the third extension 668c2 is located at the same position as the main body upstream end 2Ae. Also, in the first direction, the electrical contact 668b1 is located downstream of the main body upstream end 2Ae.

[0074] When the fixing device 6 shown in Figure 14 moves in the mounting direction relative to the device body 2, the third extension 668c2 comes into contact with the upstream end 2Ae of the main body. Since the third extension 668c2 is configured to extend in the first direction as it moves in the mounting direction, the third extension 668c2 is pressed against the upstream end 2Ae of the main body, causing the second arm 668c to rotate counterclockwise around the boss 63e. Therefore, as the third extension 668c2 moves in the mounting direction, the second arm 668c moves in the -Y direction while being pressed against the upstream end 2Ae of the main body, and the pressed portion 668c4 comes into contact with 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. As a result, as shown in Figure 15, when the pressed portion 668c4 is in contact with the contact surface 2As, the tip of the first arm 668b4 is in the same position as the upstream end 2Ae of the main body in the first direction. If the fixing device 6 moves further in the mounting direction relative to the device body 2 from the state shown in Figure 15, the tip of the first arm 668b4 comes into contact with the upstream end 2Ae of the main body, as shown in Figure 16. That is, as the second arm 668c comes into contact with the main body conductor portion 2A and moves in the first direction, the tip of the first arm 668b4 (tip) moves in the second direction, which is opposite to the first direction, and comes into contact with the upstream end 2Ae of the main body.

[0075] Figure 16 shows the state at the point when the tip of the first arm 668b4 (tip) begins to make contact with the upstream end 2Ae of the main body. At the point when the tip of the first arm 668b4 begins to make contact with the upstream end 2Ae of the main body, the tip of the first arm 668b4 (tip) is configured to extend in the first direction as it moves toward the mounting direction. Figure 16 shows the state at the point when the tip of the first arm 668b4 begins to make contact with the upstream end 2Ae of the main body. The angle θ1 formed by the direction in which the tip of the first arm 668b4 extends and the mounting direction is acute (90 degrees or less). If the angle θ1 were obtuse (90 degrees or more), the contact spring 668 and the upstream end 2Ae of the main body would interfere strongly, and the contact spring 668 may deform. Therefore, in the present invention, the angle θ1 is configured to be acute, thereby making it difficult for the contact spring 668 to deform. Furthermore, considering that deformation of the contact spring 668 occurs when the angle θ1 is greater than or equal to a predetermined angle, it is more preferable to set the angle θ1 to 30 degrees ≥ θ > 0 degrees.

[0076] In this embodiment, as a method to make the angle θ1 acute, the angle θ2 between the extension portion 668b3 and the tip portion 668b4 of the first arm is made obtuse (90 degrees or more), as shown in Figure 14. The angle θ2 can be rephrased as the angle at which the bent portion 668b5 (first bent portion) bends. By making the angle θ2 obtuse in this way, it becomes easier to configure the angle θ1 to be acute, and the deformation of the contact spring 668 can be reduced. In this embodiment, the angle θ2 is set within the range of 135 degrees ± 20 degrees (155 degrees ≥ θ2 ≥ 115 degrees). If the contact spring 668 is produced so that the angle θ2 is 115 degrees or less, there is a high possibility that the angle θ2 will be 90 degrees or less due to production variations. As mentioned above, if the angle θ1 is obtuse (90 degrees or more), the contact spring 668 and the upstream end 2Ae of the main body will interfere strongly, and the contact spring 668 may deform. For this reason, in this embodiment, the configuration is such that θ2 ≥ 115 degrees. Furthermore, it can be difficult to produce the contact spring 668 such that the angle θ2 is 155 degrees or more. For this reason, in this embodiment, 155 degrees ≥ θ2 is set considering the ease of production of the contact spring 668.

[0077] If the fixing device 6 moves further in the mounting direction relative to the device body 2 from the state shown in Figure 16, the tip of the first arm 668b4 moves in the mounting direction while in contact with the upstream end 2Ae of the main body, and also moves in the first direction. As a result, the electrical contact 668b1 (tip) is guided to the contact surface 2As and comes into contact with the contact surface 2As. Furthermore, as the fixing device 6 moves in the mounting direction, the sharp edge of the electrical contact 668b1 scratches the contact surface 2As as it moves. As a result, even if there is a coating or oxide film on the contact surface 2As, the electrical contact 668b1 scratches them off, maintaining a good electrical connection between the main body conductor 2A and the electrical contact 668b1. Finally, as shown in Figure 17, the fixing device 6 is mounted in the mounting position.

[0078] [Charge removal from pressurized rotating bodies] When a charged sheet S is conveyed to the pressurized rotating body 62, the pressurized rotating body 62 may become charged. If the fixing operation is performed while the pressurized rotating body 62 is charged, the fixing quality may deteriorate. Therefore, the fixing device 6 in this embodiment is equipped with a configuration to remove the charge accumulated on the pressurized rotating body 62. The configuration for removing the charge accumulated on the pressurized rotating body 62 will be explained using Figures 18 and 19. Figures 18 and 19 are perspective views of the fixing device 6. The fixing device 6 is equipped with a torsion coil spring 636. The torsion coil spring 636 is equipped with a coil portion 636c, a first arm portion, and a second arm portion. The lower frame 63 is equipped with a boss 63i at the end of the lower frame 63 in the first axial direction (+Y direction). The coil portion 636c is supported by the boss 63e (lower frame 63) by wrapping around the boss 63i. In other words, the boss 63i is inserted into the coil portion 636c. The second arm extends from one end of the coil portion 636c toward the electrostatic discharger 66 and engages with a groove 64b provided in the upper frame 64. In this embodiment, the groove 64b is formed in the upper frame 64, but a guide portion having the same function as the groove 64b may be provided separately in the upper frame 61. The first arm extends from the other end of the coil portion 636c toward the bearing 62c and is in contact with the bearing 62c. When the second arm is fitted into the groove 64b and the first arm is in contact with the bearing 62c, the angle between the first arm and the second arm is smaller than the free angle of the torsion coil spring 636. Therefore, the first arm and the second arm rotate in a way that widens the angle between them. More specifically, the first arm rotates toward the bearing 62c. This increases the contact pressure between the first arm and the bearing 62c, thereby stabilizing the electrical connection. On the other hand, the second arm rotates toward the bearing 62c. In this embodiment, since the second arm is fitted into the groove 64b, the rotation of the second arm is restricted by the groove 64b. In other words, the groove 64b is a guide that guides the second arm to the electrostatic discharger 66. Furthermore, because the groove 64b restricts the rotation of the second arm, the force that causes the first arm to rotate toward the bearing 62 is maintained, and the contact pressure between the first arm and the bearing 62 can be maintained at a high level.

[0079] Since the bearing 62c and the shaft 62a are in contact, the pressurized rotating body 62, the bearing 62c, and the torsion coil spring 636 are electrically connected. Also, as shown in Figure 18, the second arm is in contact with the contact portion 662c. In other words, the torsion coil spring 636 (third conductor portion) is in contact with both the first conductor portion 600a and the bearing 62c, and electrically connects (conducts) the shaft 62a (rotating axis) and the main body conductor portion 2A. Therefore, the pressurized rotating body 62 (shaft 62), the bearing 62c, the torsion coil spring 636, and the electrostatic remover 66 are electrically connected. As mentioned above, since the electrostatic remover 66 is electrically connected to the main body conductor portion 2A, the pressurized rotating body 62 is electrically connected to the main body conductor portion 2. Therefore, since the pressurized rotating body 62 is connected to ground, the charge accumulated on the pressurized rotating body 62 can be removed. This reduces the deterioration of fixing quality due to the charging of the pressurized rotating body 62.

[0080] Furthermore, in this embodiment, the fixing device 6 does not configure the grounding configuration of the pressurizing rotating body 62 and the grounding configuration of the heating unit 61 as separate components; rather, the grounding configuration of the heating unit 61 also serves as the grounding configuration of the pressurizing rotating body 62. This is to allow the charge accumulated on the pressurizing rotating body 62 to be discharged via the resistor 663. When the pressurizing rotating body 62 is connected to ground, the following problems arise. When both the transfer roller 51 and the pressurizing rotating body 62 are transporting a sheet, the voltage applied to the transfer roller 51 may flow as current through the sheet S to the pressurizing rotating body 62, potentially causing a decrease in the transfer voltage of the transfer roller 51. This is because the connection of the pressurizing rotating body 62 to ground makes it easier for current to flow from the transfer roller 51 to the pressurizing rotating body 62. Therefore, in this embodiment, a resistor 663 is connected to the pressurizing rotating body 62. This makes it more difficult for current to flow from the transfer roller 51 to the pressurizing rotating body 62.

[0081] Furthermore, in this embodiment, by combining the grounding configuration of the heating unit 61 and the grounding configuration of the pressurizing rotating body 62, there is no need to provide an additional resistor in addition to the resistor 663, compared to the case where the grounding configuration of the pressurizing rotating body 62 and the grounding configuration of the heating unit 61 are configured separately.

[0082] Furthermore, the fuser 6 on the main body side is characterized by using a pressure spring 653 as the grounding configuration. The first conductor section 600a is provided on the upper frame 64, and the second conductor section 600b is provided on the lower frame 63, so the first conductor section 600a and the second conductor section 600b are separated in the vertical direction. Therefore, in this embodiment, the first conductor section 600a and the second conductor section 600b can be connected by using a pressure spring 653 that extends in the vertical direction. In addition, by using the pressure spring 653, there is no need to newly provide a conductive member to electrically connect the first conductor section 600a and the second conductor section 600b.

[0083] [Example 2] Embodiment 2 will now be described. This embodiment differs from Embodiment 1 in that a guide portion is provided on the main body conductor portion 2A in order to reduce interference between the first arm tip portion 668b4 and the main body conductor portion 2A. Figure 20 is a top view showing the state before the fixing device 6 is mounted on the device body 2. Figure 21 is a top view showing the state after the fixing device 6 has been further inserted into the device body 2 from Figure 20. Figure 22 is a top view showing the state after the fixing device 6 has been further inserted into the device body 2 from Figure 21 and the fixing device 6 has been mounted on the device body 2 in the mounting position. As shown in Figure 20, the main body conductor portion 2A has a guide portion 2AI. The guide portion 2AI is a guide portion that guides the first arm tip portion 668b4 to the contact surface 2As. The guide portion 2AI is provided with guide surfaces 2AIs. The guide surfaces 2AIs extend in the first direction as they move toward the mounting direction and are guide surfaces that connect to the contact surface 2As. As shown in Figure 20, when the fixing device 6 moves in the mounting direction, the pressed portion 668c4 is pressed against the guide surface 2AIs and guided to the contact surface 2As. That is, the second arm 668c is guided by the guide surface 2AIs and moves in 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. That is, the tip portion 668b4 of the first arm is configured to move in the second direction, which is opposite to the first direction, as the second arm 668c moves in the first direction, and to come into contact with the guide surface 2AIs (guide portion).

[0084] Figure 21 shows the state of the fixing device 6 at the point when the tip of the first arm 668b4 begins to make contact with the guide surface 2AIs. As described above, the guide surface 2AIs extends in the first direction as it approaches the mounting direction. That is, the angle θ3 between the mounting direction and the guide surface 2AIs is acute. As a result, the tip of the first arm 668b4 is guided in the first direction, and interference between the tip of the first arm 668b4 and the main body conductor 2A can be reduced. Considering that deformation of the contact spring 668 occurs when the angle θ3 is greater than a predetermined angle, it is desirable to set the angle θ3 to 30 degrees or less and 0 degrees.

[0085] As the fixing device 6 is further inserted into the device body 2 from the state shown in Figure 21, the tip of the first arm 668b4 moves in the mounting direction while moving in the first direction, guided by the guiding surfaces 2AIs. Furthermore, the electrical contact 668b1 (tip) is guided to the contact surface 2As. The electrical contact 668b1 moves in the mounting direction while in contact with the contact surface 2As, and finally, as shown in Figure 22, the fixing device 6 is mounted in the mounting position relative to the device body 2.

[0086] As explained above, in Embodiment 2, the guiding surfaces 2AIs are configured to guide the tip portion 668b4 of the first arm to the contact surface 2As, thereby reducing the possibility of deformation of the contact spring 668.

[0087] In Example 1, the angle θ2 was set to an obtuse angle. However, if the angle θ1 is set to an acute angle, the angle θ2 may be set to within an acute angle (90 degrees) as shown in Figure 22. Setting the angle θ2 to within 90 degrees ± 10 degrees allows for a higher contact pressure on the contact surface 2As of the electrical contact 668b1 compared to the case where the angle θ2 is an obtuse angle. Furthermore, producing the contact spring 668 so that the angle θ2 is within 90 degrees ± 10 degrees is easier than producing it when the angle θ2 is extremely obtuse or narrow.

[0088] In Example 2, the lubricating portion 2AI was the main conductor portion 2A, but it may be constructed as a separate component. Furthermore, the shape of the lubricating portion 2AI may be a hemming shape or a curling shape.

[0089] [Example 3] Next, Example 3 will be described using Figure 23. Figure 23 is a top view of the fuser 6. In Example 1, the grounding configuration was such that static electricity was discharged via the brush 660, the first conductor section 600a, and the second conductor section 600b, but the pressure arm 652 may be included as part of the grounding configuration. That is, the pressure arm 652 may be made of a conductive material, and the brush 660, the pressure arm 652, and the pressure spring 653 may be electrically connected. In this case, the grounding configuration from the pressure spring 653 to the main conductor section 2a is the same as in Example 1, so the explanation will be omitted.

[0090] The fuser 6 includes a conductive intermediate conductor 658. The intermediate conductor 658 is a metal component, but any conductive component may be used. As shown in Figure 23, the intermediate conductor 658 is in contact with and electrically connected to the brush 660 and the pressure arm 652, respectively. In this embodiment, the intermediate conductor 658 is electrically connected to the belt 614 via the brush 660. This allows for stable contact with a weak force without damaging the belt 614.

[0091] Alternatively, the brush 660 may be omitted, and the intermediate conductor portion 658 may be brought into direct contact with the belt 614 to establish electrical conductivity between the intermediate conductor portion 658 and the belt 614. In this case, since the brush 660 is not provided, an inexpensive grounding configuration can be created. The intermediate conductor portion 658 is separate from the transmission member 617 or the pressure arm 652, but the intermediate conductor portion 658 may be integrally configured with the transmission member 617 or the pressure arm 652.

[0092] Alternatively, the intermediate conductor section 658 may be omitted, and the transmission member 617 shown in Figure 5 may be made of a conductive material. In this case, the transmission member 617 contacts and makes electrical contact with the belt 614 and the pressure arm 652, respectively.

[0093] [Example 4] Next, Example 4 will be described using Figure 24. Figure 24 is a schematic diagram showing a part of the belt 614. The surface 614b of the belt 614 that the brush body 660a contacts may remain as is with the coating layer of fluororesin or the like, but if the belt 614 is made of a conductive material such as a metal sleeve, for example, the coating layer may be partially removed to expose the metal layer (conductive layer).

[0094] As shown in Figure 24(a), the belt 614 has a conductive layer 614d and an insulating layer 614c that covers the conductive layer 614d from the outer surface side of the belt 614. For example, the conductive layer 614d is the base layer of the belt 614. The conductive layer 614d has an exposed portion 614cc that is not covered by the insulating layer 614c and is exposed on the outer surface side of the belt 614. The brush 660 is in contact with the exposed portion 614cc, thereby dissipating the charge of the heating unit 61 to the earth via the grounding configuration described above.

[0095] Figure 24(b) also shows the situation where the sheet S is located at the nip section np1 and the toner image is fixed by the fuser 61. Figure 24(b) also shows the case where the toner image I formed on the sheet S is at its maximum in the busbar direction (Y) of the belt 614. The portion of the belt 614 that is in the same position as the toner image I in the busbar direction (Y) of the belt 614 is called the first belt section 614I. At least a portion of the exposed section 614cc is located outside the first belt section 614I in the busbar direction of the belt 614. Similarly, at least a portion of the brush 660 is located outside the first belt section 614I in the busbar direction of the belt 614. In other words, at least a portion of the exposed section 614cc and at least a portion of the brush 660 are located outside the passage area of ​​the belt 614 through which the recording material of the maximum width that can be transported by the nip section np1 passes, in the busbar direction of the belt 614. By configuring the exposed portion 614cc in this way, the impact on fixing quality can be reduced compared to a configuration where the exposed portion 614cc is in the same position as the first portion 614I of the belt in the busbar direction of the belt 614.

[0096] In Example 1, the grounding configuration of the pressurized rotating body 62 and the grounding configuration of the heating unit 61 included a pressure spring 653 in the first conductor portion 600a, but it is not necessary to include the pressure spring 653. In other words, the first conductor portion 600a includes a conductive member that contacts the second conductor portion 600b. [Explanation of Symbols]

[0097] 2. Main unit of the device 6. Fuser 61 Heating Unit 62 Pressure rollers 652 Pressure Arm 653 Compression spring 63 Lower frame 660 brushes 600a First Conductor Section 600b Second conductor section 636 Torsion coil spring (third conductor section)

Claims

1. In a fixing device for fixing toner to a recording material, which is mounted on the main body of an image forming apparatus and has an electrically groundable main body conductor, A heating unit comprising an endless belt and a heater provided on the inner surface side of the belt for heating the belt, A pressure roller that forms a nip portion together with the heater via the belt, A pressure arm for pressing the heating unit against the pressure roller, A conductive pressure spring biases the pressure arm so that the heating unit is pressed against the pressure roller, A conductive bearing supporting the rotation axis of the pressure roller, A resin frame supporting the aforementioned bearing, A conductive brush member that contacts the belt, A first conductive portion that contacts both the brush member and the pressure spring so as to electrically connect the brush member and the pressure spring, A second conductor portion that contacts both the pressure spring and the main body conductor portion so as to electrically connect the pressure spring and the main body conductor portion, A third conductor portion that contacts both the first conductor portion and the bearing so as to electrically connect the rotating shaft and the main body conductor portion, A fixing device characterized by comprising:

2. The fixing device according to claim 1, characterized in that the first conductor portion includes a resistor.

3. The aforementioned frame is designated as the second frame, A first frame located above the second frame when the fixing device is mounted on the main body of the device, comprising a resin first frame to which the first conductor portion is attached, The second conductor portion is attached to the second frame. The fixing device according to feature 1.

4. The third conductor portion includes a torsion coil spring. The torsion coil spring includes a coil portion supported by a boss provided on the second frame, a first arm portion extending from one end of the coil portion and in contact with the bearing, and a second arm portion extending from the other end of the coil portion and in contact with the first conductor portion. The first frame has a groove formed in it into which the second arm engages. The fixing device according to claim 3, characterized in that the groove restricts the rotation of the second arm.

5. The fixing device according to claim 3, characterized in that the first frame includes a first guide that guides the side of the recording material that is conveyed in the nip portion of the heating unit facing the heating unit.

6. The belt has a conductive layer and an insulating layer that covers the conductive layer from the outer surface side of the belt. The conductive layer has an exposed portion that is not covered by the insulating layer so as to be exposed on the outer surface side of the belt, The brush member contacts the exposed portion of the conductive layer, The fixing device according to claim 1, characterized in that at least a portion of the exposed portion is located outside the belt passage area through which recording material of the maximum width that can be conveyed by the nip portion passes, in the direction of the belt's busbar.

7. A camshaft rotatably supported on the second frame, A cam supported on the camshaft so as to rotate together with the camshaft, the cam that rotates to change the pressing force applied by the pressurizing arm to the pressurizing roller of the heating unit, The fixing device according to claim 3, characterized by having the following features.

8. With the fixing device installed, the first conductor portion has an overlapping portion that overlaps with the camshaft when viewed in the vertical direction. With the fixing device mounted on the main body of the device, the overlap portion is located below the camshaft. The fixing device according to feature 7.

9. The first frame supports the camshaft. The fixing device according to feature 7.

10. The first conductor portion includes a first spring, The first spring extends in the direction of the rotation axis of the pressurizing arm and is electrically connected to the pressurizing spring. The fixing device according to feature 1.

11. The first conductor section includes the first spring, The second frame supports the camshaft and has a shaft support portion extending in the vertical direction. When the direction in which the recording material is transported in the aforementioned nip section is defined as the recording material transport direction, The downstream end of the shaft support in the recording material transport direction is designated as the downstream support end. The fixing device according to claim 7, characterized in that, in the direction of transporting the recording material, the downstream end of the support is located between the camshaft and the first spring.

12. The downstream end of the support guides the first spring so as to restrict its movement toward the camshaft. The fixing device according to feature 11.

13. The conductive layer is the base layer of the belt. The fixing device according to feature 6.

14. The second conductor portion includes a torsion coil spring. When the fixing device is mounted on the main body of the device, the torsion coil spring contacts the main body conductor. The fixing device according to feature 1.

15. The aforementioned main body conductor portion is an electrode. The fixing device according to feature 1.

16. The first conductor portion has a camshaft contact portion that contacts the camshaft. The fixing device according to feature 7.

17. In a fixing device for fixing toner to a recording material, which is mounted on the main body of an image forming apparatus and has an electrically groundable main body conductor, A heating unit comprising an endless belt and a heater provided on the inner surface side of the belt for heating the belt, A pressure roller that forms a nip portion together with the heater via the belt, A conductive bearing supporting the rotation axis of the pressure roller, A resin frame supporting the aforementioned bearing, A conductive brush member that contacts the belt, A first conductor portion that contacts the brush member so as to be electrically connected to the brush member, A second conductor portion that contacts both the first conductor portion and the main body conductor portion so as to electrically connect the first conductor portion and the main body conductor portion, A third conductor portion that contacts both the first conductor portion and the bearing so as to electrically connect the rotating shaft and the main body conductor portion, Equipped with, The second conductor portion includes a torsion coil spring. The torsion coil spring includes a coil portion and an arm extending from one end of the coil portion. When the fixing device is mounted on the main body of the device, the tip of the arm is in contact with the main body's conductor portion. A fixing device characterized by the following features.

18. The aforementioned main body conductor portion includes electrodes, When the fixing device is mounted on the main body of the device, the tip of the arm contacts the electrode. The fixing device according to feature 17.

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