Image forming apparatus

Abstract

The invention provides a new form of fixing device that builds upon conventional technology. [Solution] An image forming apparatus comprising a device body and a fixing device, wherein the fixing device comprises a heating unit, a first arm, a second arm, and a torsion coil spring which is electrically connected to the heating unit, the tip of the tip of the first arm contacts the contact surface of the main body conductor, the main body conductor includes the upstream end of the main body which is the upstream end of the main body conductor in the mounting direction and is connected to the contact surface, and in the mounting process of the fixing device, the second arm is pressed against the upstream end of the main body and moves in a first direction, the first arm moves in a second direction and its tip contacts the upstream end of the main body, and at the moment the tip begins to contact the upstream end of the main body, the tip extends toward the first direction as it moves toward the mounting direction, and the tip is guided toward the contact surface and then moves toward the mounting direction while in contact with the contact surface.

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 type of fixing device that develops conventional technology.

Means for Solving the Problems

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

[0006] An image forming apparatus including an apparatus main body of the image forming apparatus having a main body conductor portion that can be grounded, and a fixing device that is attached to the apparatus main body at a mounting position by being moved in a mounting direction with respect to the apparatus main body and fixes toner on a recording material. The fixing device includes: A heating unit including an endless belt and a heater that heats the inner surface of the belt, the heating unit having a longitudinal direction that intersects the mounting direction. A pressure roller that forms a nip together with the heater via the belt. A conductive torsion coil spring having a coil portion, a first arm extending from the coil portion toward the upstream side in the mounting direction, and a second arm extending from the coil portion toward the downstream side in the mounting direction, which is electrically connected to the heating unit, The heating unit and the frame supporting the coil section, It has, The torsion coil spring is located closer to the longitudinal center of the heating unit than the main body conductor portion. The tip of the first arm contacts the contact surface of the main body conductor, The main body conductor portion includes the upstream end of the main body that is connected to the contact surface and is the upstream end of the main body conductor portion in the mounting direction. When the longitudinal direction, specifically the direction from the torsion coil spring toward the longitudinal center of the heating unit, is defined as the first direction, and the direction opposite to the first direction is defined as the second direction, During the mounting process in which the fixing device is moved to the mounting position and attached to the device body, the second arm is configured to be pressed against the upstream end of the body and move in the first direction. During the mounting process in which the second arm moves in the first direction, the first arm is configured to move in the second direction so that its tip contacts the upstream end of the main body. During the aforementioned mounting process, at the point when the tip portion begins to contact the upstream end of the main body, the tip portion is configured to extend toward the first direction as it moves toward the mounting direction. An image forming apparatus characterized in that, during the mounting process, from the moment the tip comes into contact with the upstream end of the main body until the fixing device moves to the mounting position, the tip is guided to the contact surface and then moves in the mounting direction while in contact with the contact surface. [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 view (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] Exploded perspective view of the fixing device according to Example 1. [Figure 6] Perspective view (a, b) of the fixing device according to Example 1. [Figure 7] Top view of the fixing device according to Example 1. [Figure 8] 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 plan view (a, b) of the contact spring according to Example 1. [Figure 11] Front view and cross-sectional views (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 Example 1. [Figure 13] Exploded perspective view of the fixing device according to Example 1. [Figure 14] Front view and plan view (a, b) of the contact spring according to Example 1. [Figure 15] Plan view of the fixing device according to Example 1. [Figure 16] Plan view of the fixing device according to Example 1. [Figure 17] Plan view of the fixing device according to Example 1. [Figure 18] Plan view of the fixing device according to Example 1. [Figure 19] Plan view of the fixing device according to Example 2. [Figure 20] Plan view of the fixing device according to Example 2. [Figure 21] Plan view of the fixing device according to Example 2. [Figure 22] Plan view of the contact spring according to the modified example. [Modes for carrying out the invention]

[0009] [Example 1] Embodiments of the present invention will be described below with reference to the drawings. The dimensions, materials, shapes, and relative arrangements of the components described in the following embodiments may be appropriately modified depending on the configuration and various conditions of the apparatus to which the present invention is applied. Therefore, unless otherwise specifically stated, the scope of the present invention is not limited to these embodiments.

[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 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 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 upper surface of the sheet S being transported in the recording material transport direction. 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 being transported in the recording material transport direction.

[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, 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 be discharged via the second conductive plate 664.

[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 14. Figure 14(a) is a front view of the contact spring 668. Figure 14(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 from one end of the coil portion 668a toward the upstream side in the mounting direction, and a second arm 668c extending from the other end toward the downstream side in the mounting direction. The coil portion 668a is supported by the lower frame 63 by a boss 63e provided on the lower frame 63 around which the coil portion 668a is wound. 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 18. Figure 18 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, the second conductive plate 664, and the 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, 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. In other words, 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 with the upper frame 64 in this way, the stability of the first conductor portion 600a against external forces can be improved.

[0070] [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 15 is a top view showing the state before the fixing device 6 is attached to the device body 2. 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. Figure 18 is a top view showing the state after the fixing device 6 has been further inserted into the device body 2 from Figure 17 and the fixing device 6 has been attached to the device body 2 in the mounting position.

[0071] As shown in Figure 15, 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).

[0072] The position of the contact spring 668 before the fixing device 6 is installed will now be described. As shown in Figure 15, 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.

[0073] When the fixing device 6 shown in Figure 15 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 16). 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 16, 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 16, the tip of the first arm 668b4 comes into contact with the upstream end 2Ae of the main body, as shown in Figure 17. 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.

[0074] Figure 17 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 17 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.

[0075] 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.

[0076] If the fixing device 6 moves further in the mounting direction relative to the device body 2 from the state shown in Figure 17, 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, thereby maintaining a good electrical connection between the main body conductor 2A and the electrical contact 668b1. Finally, as shown in Figure 18, the fixing device 6 is mounted in the mounting position.

[0077] [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 19 is a top view showing the state before the fixing device 6 is mounted on the device body 2. Figure 20 is a top view showing the state after the fixing device 6 has been further inserted into the device body 2 from Figure 19. 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 and the fixing device 6 has been mounted on the device body 2 in the mounting position. As shown in Figure 19, 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 19, 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).

[0078] Figure 20 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.

[0079] As the fixing device 6 is further inserted into the device body 2 from the state shown in Figure 20, 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 21, the fixing device 6 is mounted in the mounting position relative to the device body 2.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] This embodiment includes the following configuration.

[0084] (Item 1) An image forming apparatus comprising: an apparatus body having a groundable main body conductor portion; and a fixing device which is attached to the apparatus body at a mounting position by being moved in the mounting direction relative to the apparatus body, and which fixes toner to a recording material, The fixing device is A heating unit comprising an endless belt and a heater for heating the inner surface of the belt, wherein the heating unit has a longitudinal direction that intersects the mounting direction, A pressure roller that forms a nip together with a heater via the aforementioned belt, A conductive torsion coil spring having a coil portion, a first arm extending from the coil portion toward the upstream side in the mounting direction, and a second arm extending from the coil portion toward the downstream side in the mounting direction, which is electrically connected to the heating unit, The heating unit and the frame supporting the coil section, It has, The torsion coil spring is located closer to the longitudinal center of the heating unit than the main body conductor portion. The tip of the first arm contacts the contact surface of the main body conductor, The main body conductor portion includes the upstream end of the main body that is connected to the contact surface and is the upstream end of the main body conductor portion in the mounting direction. When the longitudinal direction, specifically the direction from the torsion coil spring toward the longitudinal center of the heating unit, is defined as the first direction, and the direction opposite to the first direction is defined as the second direction, During the mounting process in which the fixing device is moved to the mounting position and attached to the device body, the second arm is configured to be pressed against the upstream end of the body and move in the first direction. During the mounting process in which the second arm moves in the first direction, the first arm is configured to move in the second direction so that its tip contacts the upstream end of the main body. During the aforementioned mounting process, at the point when the tip portion begins to contact the upstream end of the main body, the tip portion is configured to extend toward the first direction as it moves toward the mounting direction. An image forming apparatus characterized in that, during the mounting process, from the moment the tip comes into contact with the upstream end of the main body until the fixing device moves to the mounting position, the tip is guided to the contact surface and then moves in the mounting direction while in contact with the contact surface.

[0085] (Item 2) An image forming apparatus comprising: an apparatus body having a groundable main body conductor portion; and a fixing device which is attached to the apparatus body at a mounting position by being moved in the mounting direction relative to the apparatus body, and which fixes toner to a recording material, The fixing device is A heating unit comprising an endless belt and a heater for heating the inner surface of the belt, wherein the heating unit has a longitudinal direction that intersects the mounting direction, A pressure roller that forms a nip together with a heater via the aforementioned belt, A conductive torsion coil spring having a coil portion, a first arm extending from the coil portion toward the upstream side in the mounting direction, and a second arm extending from the coil portion toward the downstream side in the mounting direction, which is electrically connected to the heating unit, The heating unit and the frame supporting the coil section, It has, The torsion coil spring is located closer to the longitudinal center of the heating unit than the main body conductor portion. The tip of the first arm contacts the contact surface of the main body conductor, When the longitudinal direction, specifically the direction from the torsion coil spring toward the longitudinal center of the heating unit, is defined as the first direction, and the direction opposite to the first direction is defined as the second direction, The main body conductor portion has a guide portion that extends in the first direction as it approaches the mounting direction and is connected to the contact surface. During the mounting process in which the fixing device is moved to the mounting position and attached to the device body, the second arm is configured to be pressed by the guide portion and move in the first direction. During the mounting process in which the second arm moves in the first direction, the first arm is configured to move in the second direction so that its tip comes into contact with the guide portion. An image forming apparatus characterized in that, during the mounting process, in the step from when the tip comes into contact with the guide portion to when the fixing device moves to the mounting position, the tip is guided to the contact surface and then moves in the mounting direction while in contact with the contact surface.

[0086] (Item 3) The image forming apparatus according to item 1 or 2, characterized in that the frame has a boss inserted into the coil portion.

[0087] (Item 4) The image forming apparatus according to any one of items 1 to 3, characterized in that the frame is made of resin.

[0088] (Item 5) The belt includes a conductive layer, A pressing arm that presses the heating unit toward the pressure roller, The pressurizing arm is biased in a direction that presses the heating unit, and a conductive pressurizing spring is provided. A brush member that is in contact with the belt and is conductive, The image forming apparatus according to any one of items 1 to 4, characterized by having a first conductor portion that conducts electricity from the brush member to the pressure spring, and a second conductor portion that conducts electricity through a conductive path from the pressure spring to the torsion coil spring.

[0089] (Item 6) The second conductor portion has a conductive spring, One end of the conductive spring is in contact with one end of the compression spring, and the other end is in contact with the first arm. The image forming apparatus according to item 5, characterized in that the conductive spring biases the first arm toward the frame.

[0090] (Item 7) The image forming apparatus according to item 5 or 6, characterized in that the first conductor portion is connected to a resistor.

[0091] (Item 8) The first arm is bent at the first bending point, The image forming apparatus according to any one of items 1 to 7, characterized in that the angle at which the first bent portion bends is 115 degrees or more and 155 degrees or less.

[0092] (Item 9) The image forming apparatus according to item 1, characterized in that, at the time the tip begins to make contact with the upstream end of the main body, the angle between the direction in which the tip extends and the direction in which the mounting direction extends is 30 degrees or less and greater than 0 degrees.

[0093] (Item 10) The image forming apparatus according to item 2, characterized in that the angle between the direction in which the guide portion extends and the mounting direction is 30 degrees or less and greater than 0 degrees.

[0094] (Item 11) A method for attaching a fixing device to an image forming apparatus, wherein the fixing device is moved in the mounting direction relative to the apparatus body and the fixing device is attached to the apparatus body at the mounting position, The fixing device is A heating unit comprising an endless belt and a heater for heating the inner surface of the belt, wherein the heating unit has a longitudinal direction that intersects the mounting direction, A pressure roller that forms a nip together with a heater via the aforementioned belt, A conductive torsion coil spring having a coil portion, a first arm extending from the coil portion toward the upstream side in the mounting direction, and a second arm extending from the coil portion toward the downstream side in the mounting direction, which is electrically connected to the heating unit, The heating unit and the frame supporting the coil section, It has, The first arm has a tip portion including the tip, The device body has a groundable main body conductor portion, The main body conductor portion has a contact surface and an upstream end of the main body that is connected to the contact surface and is the upstream end of the main body conductor portion in the mounting direction. When the longitudinal direction, specifically the direction from the torsion coil spring toward the longitudinal center of the heating unit, is defined as the first direction, and the direction opposite to the first direction is defined as the second direction, The mounting method of the fixing device is, The fixing device moves in the mounting direction, causing the second arm to be pressed against the upstream end of the main body and move in the first direction, and as the second arm moves in the first direction, the first arm moves in the second direction; The second step involves the tip portion extending toward the first direction as it moves toward the mounting direction, and the tip portion contacting the upstream end of the main body; A method for mounting a fixing device, characterized by comprising: a third step in which the tip is guided to the contact surface, and then moved in the mounting direction while in contact with the contact surface, thereby positioning the fixing device at the mounting position.

[0095] (Item 12) A method for attaching a fixing device to an image forming apparatus, wherein the fixing device is moved in the mounting direction relative to the apparatus body and the fixing device is attached to the apparatus body at the mounting position, The fixing device is A heating unit comprising an endless belt and a heater for heating the inner surface of the belt, wherein the heating unit has a longitudinal direction that intersects the mounting direction, A pressure roller that forms a nip together with a heater via the aforementioned belt, A conductive torsion coil spring having a coil portion, a first arm extending from the coil portion toward the upstream side in the mounting direction, and a second arm extending from the coil portion toward the downstream side in the mounting direction, which is electrically connected to the heating unit, The heating unit and the frame supporting the coil section, It has, The first arm has a tip portion including the tip, The device body has a groundable main body conductor portion, When the longitudinal direction, specifically the direction from the torsion coil spring toward the longitudinal center of the heating unit, is defined as the first direction, and the direction opposite to the first direction is defined as the second direction, The main body conductor portion has a contact surface and a guide portion that extends in the first direction as it approaches the mounting direction and is connected to the contact surface. The mounting method of the fixing device is, The fixing device moves in the mounting direction, causing the second arm to be pressed against the guide portion and move in the first direction, and as the second arm moves in the first direction, the first arm moves in the second direction; The second step involves the tip portion extending toward the first direction as it moves toward the mounting direction, and the tip portion contacting the guide portion in this state, A method for mounting a fixing device, characterized by comprising: a third step in which the tip is guided to the contact surface, and then the tip is moved in the mounting direction while in contact with the contact surface, thereby positioning the fixing device at the mounting position. [Explanation of Symbols]

[0096] 1. Image forming apparatus 2. Main unit of the device 6. Fixing device 614 Belt 611 Heater 61 Heating Unit 62 Pressurized Rotating Body 668 Contact spring 668a Coil section 668b First Arm 668c Second Arm 63 Lower frame 2A Main conductor section 2Ae Main unit upstream end 668b4 First arm tip 668b1 Electrical contact 2As contact surface

Claims

1. An image forming apparatus comprising: an apparatus body having a groundable main body conductor portion; and a fixing device which is attached to the apparatus body at a mounting position by being moved in the mounting direction relative to the apparatus body, and which fixes toner to a recording material, The fixing device is A heating unit comprising an endless belt and a heater for heating the inner surface of the belt, wherein the heating unit has a longitudinal direction that intersects the mounting direction, A pressure roller that forms a nip together with a heater via the aforementioned belt, A conductive torsion coil spring having a coil portion, a first arm extending from the coil portion toward the upstream side in the mounting direction, and a second arm extending from the coil portion toward the downstream side in the mounting direction, which is electrically connected to the heating unit, The heating unit and the frame supporting the coil section, It has, The torsion coil spring is located closer to the longitudinal center of the heating unit than the main body conductor portion. The tip of the first arm contacts the contact surface of the main body conductor, The main body conductor portion includes the upstream end of the main body that is connected to the contact surface and is the upstream end of the main body conductor portion in the mounting direction. When the longitudinal direction, specifically the direction from the torsion coil spring toward the longitudinal center of the heating unit, is defined as the first direction, and the direction opposite to the first direction is defined as the second direction, During the mounting process in which the fixing device is moved to the mounting position and attached to the device body, the second arm is configured to be pressed against the upstream end of the body and move in the first direction. During the mounting process in which the second arm moves in the first direction, the first arm is configured to move in the second direction so that its tip contacts the upstream end of the main body. During the aforementioned mounting process, at the point when the tip portion begins to contact the upstream end of the main body, the tip portion is configured to extend toward the first direction as it moves toward the mounting direction. An image forming apparatus characterized in that, during the mounting process, from the moment the tip comes into contact with the upstream end of the main body until the fixing device moves to the mounting position, the tip is guided to the contact surface and then moves in the mounting direction while in contact with the contact surface.

2. An image forming apparatus comprising: an apparatus body having a groundable main body conductor portion; and a fixing device which is attached to the apparatus body at a mounting position by being moved in the mounting direction relative to the apparatus body, and which fixes toner to a recording material, The fixing device is A heating unit comprising an endless belt and a heater for heating the inner surface of the belt, wherein the heating unit has a longitudinal direction that intersects the mounting direction, A pressure roller that forms a nip together with a heater via the aforementioned belt, A conductive torsion coil spring having a coil portion, a first arm extending from the coil portion toward the upstream side in the mounting direction, and a second arm extending from the coil portion toward the downstream side in the mounting direction, which is electrically connected to the heating unit, The heating unit and the frame supporting the coil section, It has, The torsion coil spring is located closer to the longitudinal center of the heating unit than the main body conductor portion. The tip of the first arm contacts the contact surface of the main body conductor, When the longitudinal direction, specifically the direction from the torsion coil spring toward the longitudinal center of the heating unit, is defined as the first direction, and the direction opposite to the first direction is defined as the second direction, The main body conductor portion has a guide portion that extends in the first direction as it approaches the mounting direction and is connected to the contact surface. During the mounting process in which the fixing device is moved to the mounting position and attached to the device body, the second arm is configured to be pressed by the guide portion and move in the first direction. During the mounting process in which the second arm moves in the first direction, the first arm is configured to move in the second direction so that its tip comes into contact with the guide portion. An image forming apparatus characterized in that, during the mounting process, in the step from when the tip comes into contact with the guide portion to when the fixing device moves to the mounting position, the tip is guided to the contact surface and then moves in the mounting direction while in contact with the contact surface.

3. The image forming apparatus according to claim 1 or 2, characterized in that the frame has a boss inserted into the coil portion.

4. The image forming apparatus according to claim 1 or 2, characterized in that the frame is made of resin.

5. The belt includes a conductive layer, A pressing arm that presses the heating unit toward the pressure roller, The pressurizing arm is biased in a direction that presses the heating unit, and a conductive pressurizing spring is provided. A brush member that is in contact with the belt and is conductive, The image forming apparatus according to claim 1 or 2, characterized by having a first conductor portion that conducts electrical current from the brush member to the pressure spring, and a second conductor portion that conducts electrical current from the pressure spring to the torsion coil spring.

6. The second conductor portion has a conductive spring, One end of the conductive spring is in contact with one end of the compression spring, and the other end is in contact with the first arm. The image forming apparatus according to claim 5, characterized in that the conductive spring biases the first arm toward the frame.

7. The image forming apparatus according to claim 5, characterized in that the first conductor portion is connected to a resistor.

8. The first arm is bent at the first bending point, The image forming apparatus according to claim 1 or 2, characterized in that the angle at which the first bent portion bends is 115 degrees or more and 155 degrees or less.

9. The image forming apparatus according to claim 1, characterized in that, at the time the tip begins to make contact with the upstream end of the main body, the angle between the direction in which the tip extends and the direction in which the mounting direction extends is 30 degrees or less and greater than 0 degrees.

10. The image forming apparatus according to claim 2, characterized in that the angle between the direction in which the guide portion extends and the mounting direction is 30 degrees or less and greater than 0 degrees.

11. A method for attaching a fixing device to an image forming apparatus, wherein the fixing device is moved in the mounting direction relative to the apparatus body and the fixing device is attached to the apparatus body at the mounting position, The fixing device is A heating unit comprising an endless belt and a heater for heating the inner surface of the belt, wherein the heating unit has a longitudinal direction that intersects the mounting direction, A pressure roller that forms a nip together with a heater via the aforementioned belt, A conductive torsion coil spring having a coil portion, a first arm extending from the coil portion toward the upstream side in the mounting direction, and a second arm extending from the coil portion toward the downstream side in the mounting direction, which is electrically connected to the heating unit, The heating unit and the frame supporting the coil section, It has, The first arm has a tip portion including the tip, The device body has a groundable main body conductor portion, The main body conductor portion has a contact surface and an upstream end of the main body that is connected to the contact surface and is the upstream end of the main body conductor portion in the mounting direction. When the longitudinal direction, specifically the direction from the torsion coil spring toward the longitudinal center of the heating unit, is defined as the first direction, and the direction opposite to the first direction is defined as the second direction, The mounting method of the fixing device is, The fixing device moves in the mounting direction, causing the second arm to be pressed against the upstream end of the main body and move in the first direction, and as the second arm moves in the first direction, the first arm moves in the second direction; The second step involves the tip portion extending toward the first direction as it moves toward the mounting direction, and the tip portion contacting the upstream end of the main body; A method for mounting a fixing device, characterized by comprising: a third step in which the tip is guided to the contact surface, and then moved in the mounting direction while in contact with the contact surface, thereby positioning the fixing device at the mounting position.

12. A method for attaching a fixing device to an image forming apparatus, wherein the fixing device is moved in the mounting direction relative to the apparatus body and the fixing device is attached to the apparatus body at the mounting position, The fixing device is A heating unit comprising an endless belt and a heater for heating the inner surface of the belt, wherein the heating unit has a longitudinal direction that intersects the mounting direction, A pressure roller that forms a nip together with a heater via the aforementioned belt, A conductive torsion coil spring having a coil portion, a first arm extending from the coil portion toward the upstream side in the mounting direction, and a second arm extending from the coil portion toward the downstream side in the mounting direction, which is electrically connected to the heating unit, The heating unit and the frame supporting the coil section, It has, The first arm has a tip portion including the tip, The device body has a groundable main body conductor portion, When the longitudinal direction, specifically the direction from the torsion coil spring toward the longitudinal center of the heating unit, is defined as the first direction, and the direction opposite to the first direction is defined as the second direction, The main body conductor portion has a contact surface and a guide portion that extends in the first direction as it approaches the mounting direction and is connected to the contact surface. The mounting method of the fixing device is, The fixing device moves in the mounting direction, causing the second arm to be pressed against the guide portion and move in the first direction, and as the second arm moves in the first direction, the first arm moves in the second direction; The second step involves the tip portion extending toward the first direction as it moves toward the mounting direction, and the tip portion contacting the guide portion in this state, A method for mounting a fixing device, characterized by comprising: a third step in which the tip is guided to the contact surface, and then the tip is moved in the mounting direction while in contact with the contact surface, thereby positioning the fixing device at the mounting position.

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