Replaceable device in image forming apparatus and contact spring for replaceable device

Abstract

To improve assemblability while ensuring good electrical connection using a contact spring.SOLUTION: A contact spring 50 has a first arm 51 that extends from one end of a coil 55, the first arm 51 having an electrical contact 51A at a leading end in contact with an electrode 2A of an apparatus body 2, and a second arm 52 that extends in a direction different from the first arm 51 from the other end of the coil 55. In a state in which a replaceable device 1 is not mounted in the apparatus body 2, the contact spring 50 is urged by an urging spring 60, and thereby the electrical contact 51A is located at a retreat position. When the replaceable device 1 is mounted in the apparatus body 2, the second arm 52 is pressed by the apparatus body 2, and thereby the first arm 51 rotates around a boss 11B and the electrical contact 51A is located at a projection position where it projects from a frame 10 beyond the retreat position.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a replaceable device for an image forming apparatus, which can be electrically connected to the main body of the image forming apparatus by a contact spring, and to a contact spring for the replaceable device. [Background technology]

[0002] In a conventional replaceable fixing unit, parts that need to be grounded are connected by a metal spring, ensuring a reliable electrical connection even if one part moves relative to the other.

[0003] For example, Patent Document 1 describes a structure in which a guide member 26 that guides a sheet at the outlet of the fixing unit and a reinforcing plate 27 are connected and electrically connected by a torsion coil spring 29. Furthermore, Patent Document 2 describes a structure in which an arm 81 that presses a heat unit 22 of the fixing unit toward a pressure roller 21 and a connecting part 98 are connected and electrically connected by a biasing member 82 and a spring 94. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-192704 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-206344 Summary of the Invention [Problem to be solved by the invention]

[0005] In order to obtain a good electrical connection with a contact spring, it is sometimes desirable to provide a pointed tip on the member that makes up the spring, and to have this tip bite into the metal frame of the device body to establish electrical continuity. By doing so, even if there is a paint film, oxide film, or dirt on the metal frame, it can be scraped off and electrical continuity can be achieved with low resistance.

[0006] However, if the sharp tip of the contact spring is left exposed, the tip of the contact spring is likely to get caught on something other than the metal frame or the like to be electrically connected during assembly, which poses the problem of time and effort required for assembly.

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a replaceable device for an image forming apparatus and a contact spring for the replaceable device that improves assembly while ensuring good electrical connection by the contact spring. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, the replaceable device of the image forming apparatus of the present invention comprises a frame having a boss, a contact spring having a coil that is supported by the boss by fitting around the outer periphery of the boss, and a biasing spring that biases the contact spring in one rotational direction around the boss. The contact spring has a first arm extending from one end of the coil and having an electrical contact at its tip that contacts an electrode on the main body of the image forming device, and a second arm extending from the other end of the coil in a direction different from the first arm. When the replaceable device is not attached to the device body, the contact spring is biased by the biasing spring, so that the electrical contact is located at the retracted position. When the replaceable device is attached to the device body, the second arm is pressed against the device body, so that the first arm rotates around the boss, and the electrical contact is located at a protruding position that protrudes from the frame further than the retracted position.

[0009] With this configuration, when the replaceable device is not attached to the device body, the electrical contact at the tip of the first arm is located in the retracted position, making it less likely to get caught on other objects during assembly. On the other hand, when the replaceable device is attached to the device body, the second arm is pressed against the device body, causing the first arm to rotate around the boss, causing the electrical contact to protrude from the frame beyond the retracted position, making it easier to ensure electrical continuity between the electrical contact and the electrode of the device body after attachment. In other words, assembly can be improved while ensuring good electrical connection via the contact spring.

[0010] The first arm may have a bent portion, and the frame may have a stopper surface that comes into contact with the bent portion due to the biasing force of the biasing spring when the replaceable device is not attached to the apparatus body.

[0011] The first arm may have a spring hook portion extending from one end of the coil in the axial direction of the coil, with which one end of the biasing spring engages, and an extension portion extending from the spring hook portion in a direction away from the center of the coil and connected to the bent portion.

[0012] The contact spring may consist of a single metal wire.

[0013] The electrical contacts preferably have sharp edges, which can improve electrical connection between the electrodes of the device body and the electrical contacts.

[0014] The second arm may have a pressed portion that is bent so as to protrude from the frame when the replaceable device is not attached to the apparatus body. The pressed portion may be configured to be pressed against the device body when the replaceable device is attached to the device body.

[0015] The second arm may have a bent retaining portion at its tip, which is capable of engaging with the frame when the contact spring rotates in one rotation direction.

[0016] The replaceable device may include a heating element for heating the sheet and a pressure element for pressing the sheet against the heating element, and the biasing spring may serve as a conductive line for electrically connecting the heating element and the contact spring to ground the heating element.

[0017] According to this configuration, the biasing spring also serves as a conductive wire for grounding, thereby making it possible to suppress an increase in the number of parts.

[0018] The contact spring for solving the above-mentioned problem is a contact spring for earthing a replaceable device of an image forming apparatus, and comprises a coil that fits around the outer periphery of a boss on the frame of the replaceable device, a first arm extending from one end of the coil and having an electrical contact at its tip that contacts an electrode on the main body of the image forming apparatus, and a second arm extending from the other end of the coil in a direction different from that of the first arm. The first arm includes a spring hook portion that extends from one end of the coil in the axial direction of the coil and engages with one end of the biasing spring, an extension portion that extends from the spring hook portion in a direction away from the center of the coil, and a tip portion that bends and extends from the extension portion in a direction different from the radial direction of the coil, the tip portion having an electrical contact point. When the replaceable device is not attached to the device body, the contact spring is biased by the biasing spring, so that the electrical contact is located at the retracted position. When the replaceable device is attached to the device body, the second arm is pressed against the device body, so that the first arm rotates around the boss, and the electrical contact is located at a protruding position that protrudes from the frame further than the retracted position.

[0019] With such a contact spring, when the replaceable device is attached to the device body, the second arm is pressed against the device body, causing the first arm to rotate around the boss, making it easier for the electrical contact to protrude from the frame further than the retracted position. [Effects of the Invention]

[0020] According to the present invention, it is possible to improve the ease of assembly while ensuring good electrical connection by the contact spring. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. [Figure 2] FIG. [Figure 3] 1A is a plan view of a contact spring, and FIG. 1B is a front view of the contact spring. [Figure 4] FIG. 2 is a perspective view of the frame of the fixing unit as viewed obliquely from below. [Figure 5] This figure explains the action when attaching an interchangeable device to the device body, showing (a) the state in which the contact spring approaches the electrode before the interchangeable device is attached to the device body, and (b) the state in which the contact spring rotates during the process of attaching the interchangeable device to the device body. [Figure 6] 1 shows the state after the replaceable device is attached to the main body of the apparatus and the electrical contacts of the contact springs are in contact with the electrodes. DETAILED DESCRIPTION OF THE INVENTION

[0022] Next, an embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, the replaceable device 1 of this embodiment is a component that can be removed from or attached to the device body 2 of the image forming device, and as an example, is a fuser that thermally fuses a toner image formed on a sheet. The replaceable device 1 is inserted into the device body 2 through an opening 2B formed by opening a cover 2C on the rear side of the device body 2. The device body 2 has an electrode 2A. The electrode 2A is a metal plate that also serves as the frame of the device body 2. The electrode 2A is electrically grounded. The replaceable device 1 includes a contact spring 50, and as will be described in detail later, attaching the replaceable device 1 to the device body 2 electrically connects an electrical contact 51A of the contact spring 50 to the electrode 2A.

[0023] 2, the replaceable device 1 includes a frame 10, a heating member 20, a pressure member 30, a pressure arm 40, a pressure spring 45, a contact spring 50, and a biasing spring 60. Note that Fig. 2 omits the detailed configuration of the frame 10.

[0024] The frame 10 mainly comprises side walls 11 and 12 spaced apart in the axial direction of the pressure member 30 (hereinafter simply referred to as the "axial direction") and a connecting portion 13 connecting the side walls 11 and 12. For convenience, in the following description, the up and down directions in FIG. 2 are referred to as up and down, the direction perpendicular to the up and down directions and the axial direction is referred to as the front-rear direction, and the left side of FIG. 2 is referred to as the front and the right side as the rear. The side walls 11 and 12 are U-shaped with an open top (see also FIG. 4). The side walls 11 and 12 have a pair of rails 11R and 12R extending parallel to each other inside the U-shape. A pressure arm 40, a contact spring 50, and a biasing spring 60 are attached to one of the side walls 11. The other side wall 12 has a structure that is approximately symmetrical in the axial direction to the one side wall 11, except for the structure related to the attachment of the contact spring 50, so below, with regard to the side walls 11 and 12, only the structure of the one side wall 11 will be described.

[0025] The heating member 20 is a member that heats the sheet. The heating member 20 includes a heater (not shown) and a belt that rotates around the heater. The axial ends of the heating member 20 are engaged with the rails 11R and 12R of the frame 10. This allows the heating member 20 to slide up and down while being guided by the rails 11R and 12R.

[0026] The pressure member 30 is a member that presses the sheet against the heating member 20. The pressure member 30 is a roller with a metal shaft covered with an elastic member. The pressure member 30 is rotatably supported by the side walls 11 and 12 of the frame 10 via bearings 31.

[0027] The pressure arm 40 is made of a U-shaped metal plate that opens downward. One end of the pressure arm 40 is rotatably supported by a shaft 11S provided on the side wall 11 of the frame. The center of the pressure arm 40 contacts the end of the heating element 20 from above. The pressure arm 40 has a groove 42 at the other end. The pressure spring 45 is a tension spring made of metal wire. The pressure spring 45 has a hook 45A at one end and a hook 45B at the other end. The hook 45A at one end of the pressure spring 45 is hooked into the groove 42 of the pressure arm 40. The side wall 11 has a groove 19 below the groove 42 of the pressure arm 40. The hook 45B at the other end of the pressure spring 45 is hooked into the groove 19 of the side wall 11. The pressure spring 45 constantly urges the pressure arm 40 downward. As a result, the end of the heating member 20 is biased from above by the pressure arm 40 , and the heating member 20 is pressed against the pressure member 30 .

[0028] 3(a) and 3(b), the contact spring 50 is a torsion coil spring. The contact spring 50 is made of a single metal wire. The contact spring 50 has a coil 55, a first arm 51 extending from one end of the coil 55, and a second arm 52 extending from the other end of the coil 55 in a direction different from that of the first arm 51.

[0029] 2 and 4, the side wall 11 has a boss 11B (see FIG. 4) that protrudes downward below the bearing 31. The coil 55 is fitted onto the outer periphery of the boss 11B and is supported by the boss 11B. The contact spring 50 is rotatable around the boss 11B.

[0030] 3(a) and 3(b), the first arm 51 has, at its tip, an electrical contact 51A that comes into contact with the electrode 2A of the device body 2. In detail, the first arm 51 has a spring hook portion 51B, an extending portion 51C, a hook portion 51D, and a bent portion 51E.

[0031] The spring hook portion 51B extends from one end of the coil 55 in the axial direction of the coil 55. As shown in FIGS. 2 and 5(a), one end 62 of the biasing spring 60 engages with the spring hook portion 51B. The biasing spring 60 is a tension spring. The other end 63 of the biasing spring 60 engages with the hook 45B of the pressure spring 45. As a result, the contact spring 50 is biased in one rotational direction by the biasing spring 60. Specifically, the contact spring 50 is biased in the clockwise direction in FIG. 5(a).

[0032] As shown in FIGS. 4 and 5(a), the frame 10 has a stopper surface 18 that comes into contact with the bent portion 51E due to the biasing force of the biasing spring 60 when the replaceable device 1 is not attached to the apparatus body 2. When the replaceable device 1 is not attached to the apparatus body 2, the posture of the first arm 51 is determined by the bent portion 51E coming into contact with the stopper surface 18. The position of the electrical contact 51A at this time is referred to as the retracted position. Note that when the contact spring 50 is not in contact with the electrode 2A, as shown in FIG. 5(a), the replaceable device 1 is not completely attached, and therefore this is referred to as the state in which the replaceable device 1 is not attached to the apparatus body 2.

[0033] Returning to Figures 3(a) and (b), extension portion 51C extends from spring hook portion 51B in a direction away from the center of coil 55 and connects to bent portion 51E. Hook portion 51D bends from extension portion 51C and extends in a direction perpendicular to the axial direction of coil 55. Electrical contact 51A is a pointed portion at the tip of first arm 51. Electrical contact 51A has the same shape as when the metal wire is cut, and has a sharp edge without being rounded or otherwise processed. In Figures 3(a) and (b), the metal wire is depicted as if it were cut cleanly at a right angle, but it may have an irregular shape, such as a shape imprinted with the shape of a cutting tool blade.

[0034] The second arm 52 has a second extending portion 52A, a third extending portion 52B, and a retaining portion 52C. The second extending portion 52A extends from the other end of the coil 55 in a direction away from the center of the coil 55. The third extending portion 52B bends and extends from the end of the second extending portion 52A farthest from the coil 55. The third extending portion 52B extends in a direction perpendicular to the axial direction of the coil 55 and in a direction different from that of the second extending portion 52A. The portion that bends from the second extending portion 52A to the third extending portion 52B is the pressed portion 52F. As shown in FIGS. 4 and 5(a), the pressed portion 52F is bent so as to protrude from the frame 10 when the replaceable device 1 is not attached to the apparatus main body 2.

[0035] Returning to FIGS. 3(a) and 3(b), the retaining portion 52C extends in the axial direction of the coil 55 from the end of the third extending portion 52B farther from the coil 55. 4, the frame 10 has, in front of the boss 11B, a slit 14 that extends long in a direction perpendicular to the axis of the boss 11B, and a retaining wall 15 that is disposed adjacent to the slit 14. The second arm 52 has the third extending portion 52B inserted into the slit 14, and the retaining portion 52C extending from the retaining wall 15 on the side opposite to the side on which the pressed portion 52F is located. This allows the retaining portion 52C to engage with the retaining wall 15 when the contact spring 50 rotates in one direction such that the pressed portion 52F protrudes.

[0036] The frame 10 has a first protective wall 16 located on one side of the hook portion 51D in the axial direction of the coil 55 when the replaceable device 1 is not attached to the apparatus body 2, and a second protective wall 17 located on the other side of the hook portion 51D in the axial direction of the coil 55. That is, when the replaceable device 1 is not attached to the apparatus body 2, the hook portion 51D is located in the gap between the first protective wall 16 and the second protective wall 17. When the replaceable device 1 is not attached to the apparatus body 2, the electrical contacts 51A protrude only slightly from the first protective wall 16 and the second protective wall 17. As a result, when the replaceable device 1 is not attached to the apparatus body 2, the electrical contacts 51A are protected by the first protective wall 16 and the second protective wall 17 and are less likely to get caught on other objects. Desirably, when the replaceable device 1 is not attached to the apparatus body 2, the electrical contacts 51A are positioned between the first protective wall 16 and the second protective wall 17 without protruding from the first protective wall 16 and the second protective wall 17. In this way, the electrical contacts 51A do not protrude from the frame 10, making it even less likely that other objects will get caught on the electrical contacts 51A.

[0037] With the above-described configuration, the biasing spring 60 is electrically connected to the heating member 20 via the pressure spring 45 and the pressure arm 40 (see FIG. 2). In addition, the biasing spring 60 is in contact with the spring hook portion 51B of the contact spring 50, and therefore the biasing spring 60 electrically connects the heating member 20 and the contact spring 50, and serves as a conductive line for earthing the heating member 20.

[0038] The function and effect of the contact spring 50 in the replaceable device 1 configured as above will be described. 5(a), when the replaceable device 1 is inserted into the apparatus main body 2 from rear to front, the second arm 52 of the contact spring 50 approaches the electrode 2A. During this process, the electrical contact 51A of the contact spring 50 hardly protrudes from the frame 10, so the electrical contact 51A is unlikely to get caught on other objects.

[0039] As shown in Fig. 5(b), when the replaceable device 1 is further pushed forward from the state shown in Fig. 5(a), the pressed portion 52F of the second arm 52 is pressed against the electrode 2A. Then, the second arm 52 rotates counterclockwise in Fig. 5 around the boss 11B, and accordingly, the coil 55 and the first arm 51 also rotate counterclockwise around the boss 11B. As a result, the electrical contact 51A is positioned at a protruding position that protrudes from the frame 10 further than the retracted position.

[0040] 6, when the replaceable device 1 is further pushed forward, the hook portion 51D is pressed by the electrode 2A, causing the first arm 51 to rotate clockwise around the boss 11B, and the electrical contact 51A comes into contact with the surface of the electrode 2A. As the replaceable device 1 moves forward, the sharp edge of the electrical contact 51A scratches the surface of the electrode 2A as it moves forward. As a result, even if there is a coating or oxide film on the surface of the electrode 2A, the electrical contact 51A scrapes it off, thereby establishing a firm electrical connection between the metal portion of the electrode 2A and the electrical contact 51A.

[0041] Thus, according to the replaceable device 1 of this embodiment, when the replaceable device 1 is not attached to the apparatus body 2, the electrical contact 51A at the tip of the first arm 51 is located in the retracted position, making it less likely for the electrical contact 51A to get caught on something during assembly. On the other hand, when the replaceable device 1 is attached to the apparatus body 2, the second arm 52 is pressed against the apparatus body 2, causing the first arm 51 to rotate around the boss 11B, and the electrical contact 51A protrudes from the frame beyond the retracted position, making it easier to ensure electrical continuity between the electrical contact 51A and the electrode 2A of the apparatus body 2 after attachment. In other words, it is possible to improve assembly efficiency while ensuring good electrical connection by the contact spring 50.

[0042] Furthermore, since the electrical contact 51A has a sharp edge, the electrical contact 51A can scrape off the coating or oxide film on the surface of the electrode 2A, thereby improving the electrical connection between the electrode 2A and the electrical contact 51A.

[0043] Furthermore, since the biasing spring 60 also serves as a conductive line for grounding the heating member 20, an increase in the number of parts can be suppressed.

[0044] Although one embodiment has been described above, the present invention is not limited to the above embodiment and can be practiced with appropriate modifications.

[0045] For example, in the above embodiment, the contact spring 50 is positioned so that when the replaceable device 1 is attached to the device main body 2, the second arm 52 enters the device main body 2 before the first arm 51, but it may also be positioned so that the first arm 51 enters the device main body 2 before the second arm 52.

[0046] The contact spring does not have to have a retaining portion. For example, the second arm may be shaped so that the tip of the second arm does not protrude from the frame when the electrical contact is in the retracted position.

[0047] The replaceable device is not limited to the fixing unit, but may also be a developing cartridge or a drum cartridge.

[0048] The elements described in the above-described embodiment and modifications may be implemented in any combination. [Explanation of symbols]

[0049] 1 Replaceable Device 2. Device body 2A electrode 10 frames 11B Boss 20 Heating element 30 Pressure member 50 Contact spring 51 First Arm 51A Electrical Contact 52 Second Arm 55 coil 60 bias spring

Claims

1. A replaceable device for an image forming apparatus, comprising: a frame having a boss; a contact spring having a coil that is fitted around the outer periphery of the boss and supported by the boss; a biasing spring that biases the contact spring in one rotational direction around the boss, The contact spring is a first arm extending from one end of the coil and having an electrical contact at its tip that contacts an electrode of the main body of the image forming apparatus; a second arm extending from the other end of the coil in a direction different from that of the first arm, When the replaceable device is not attached to the apparatus body, the contact spring is biased by the biasing spring, so that the electrical contact is located at a retracted position; An interchangeable device for an image forming apparatus, characterized in that when the interchangeable device is attached to the apparatus main body, the second arm is pressed against the apparatus main body, causing the first arm to rotate around the boss, and the electrical contact is positioned at a protruding position that protrudes from the frame more than the retracted position.

2. the first arm has a bent portion, 2. A replaceable device for an image forming apparatus according to claim 1, wherein the frame has a stopper surface that contacts the bent portion due to the biasing force of the biasing spring when the replaceable device is not attached to the apparatus main body.

3. The first arm is a spring hook portion extending from the one end of the coil in the axial direction of the coil, the spring hook portion being engaged with one end of the biasing spring; 3. The replaceable device of the image forming apparatus according to claim 2, further comprising an extension portion extending from the spring hook portion in a direction away from the center of the coil and connected to the bent portion.

4. 4. The replaceable device of an image forming apparatus according to claim 1, wherein the contact spring is made of a single metal wire.

5. 5. The replaceable device of an image forming apparatus according to claim 1, wherein the electrical contacts have sharp edges.

6. the second arm has a pressed portion that is bent so as to protrude from the frame when the replaceable device is not attached to the apparatus body, 6. The replaceable device for an image forming apparatus according to claim 1, wherein the pressed portion is pressed against the apparatus body when the replaceable device is attached to the apparatus body.

7. A replaceable device for an image forming apparatus described in any one of claims 1 to 6, characterized in that the second arm has a bent retaining portion at its tip that can engage with the frame when the contact spring rotates in one of the rotation directions.

8. The replaceable device is a heating element for heating the sheet; a pressure member that presses the sheet against the heating member, 8. A replaceable device for an image forming apparatus according to claim 1, wherein the biasing spring serves as a conductive wire for electrically connecting the heating element and the contact spring to ground the heating element.

Images