Unit positioning mechanism and image forming apparatus

Abstract

The invention provides a unit positioning mechanism and an image forming apparatus. The unit positioning mechanism includes a first unit, a second unit, and a positioning member, the positioning member having a cylindrical portion, a hook portion, and a restricted portion, the second unit having a unit side portion, a support shaft, and a restricting portion, the hook portion restricting rotation of the second unit by engaging with the boss portion, and the restricted portion restricting rotation of the second unit by engaging with the support shaft. The restricting portion overlaps the restricted portion from the outside in the predetermined direction in a state in which the hook portion is engaged with the boss portion, and is provided with a torsion coil spring having a coil spring portion disposed in the cylindrical portion, a first arm portion, and a second arm portion, the torsion coil spring being engaged with the positioning member via the first arm portion, and the unit-side portion being engaged with the second arm portion. A force is applied to the positioning member in a direction in which the hook portion engages with the boss portion.

Description

Technical Field

[0001] The present invention relates to a unit positioning mechanism and an image forming device. Background Art

[0002] A conventional image forming apparatus includes a unit that can rotate with one end edge as a fulcrum, such as a cover member.

[0003] In the past, for example, the rotation of the unit was restricted by engaging the hook of the positioning component with the unit. That is, the unit was positioned. In this structure, if the positioning component is displaced (for example, the positioning component falls off), the unit is also displaced. However, if the positioning component is fixed so that it does not displace, the decomposability of the positioning component and its surroundings becomes poor. Summary of the invention

[0004] The present invention is made to solve the above-mentioned problems, and its object is to provide a unit positioning mechanism and an image forming apparatus that can suppress the reduction in the disassembly of the positioning member and its surroundings and suppress the positional deviation of the unit in a structure in which the rotation of the unit is restricted by the positioning member.

[0005] In order to achieve the above-mentioned purpose, the unit positioning mechanism of the first aspect of the present invention includes: a first unit having a boss portion; a second unit, which can be displaced between a first position positioned relative to the first unit and a second position other than the first position by rotating around an axis extending along a specified direction; and a positioning component to maintain the second unit in the first position, the positioning component comprising: a cylindrical portion, with the specified direction as the cylindrical axis direction; a hook portion, as viewed from the specified direction, arranged radially outward of the cylindrical portion, and engaged with the boss portion in a manner of embracing the boss portion from one side in the circumferential direction centered on the cylindrical axis of the cylindrical portion; and a restricted portion, as viewed from the specified direction, arranged radially outward of the cylindrical portion and at a position different from the hook portion in the circumferential direction, the second unit comprising: a unit side portion; a support shaft protruding from the unit side portion to the outside of the specified direction, for the cylindrical portion to be embedded from the outside of the specified direction, so as to support the positioning component The cam is engaged with the boss portion when the second unit is in the first position, thereby limiting the rotation of the second unit from the first position to the second position, and the limiting portion overlaps with the restricted portion from the outside of the specified direction in the state where the hook portion is engaged with the boss portion, thereby limiting the movement of the positioning member to the outside of the specified direction, and the unit positioning mechanism includes a torsion coil spring, which includes: a coil spring portion, which is arranged on the cylindrical portion; a first arm portion extending from one end of the coil spring portion; and a second arm portion extending from the other end of the coil spring portion, and the torsion coil spring applies force to the positioning member in the direction in which the hook portion and the boss portion are engaged through the first arm portion engaging with the positioning member and the second arm portion engaging with the unit side portion.

[0006] The image forming device of the second aspect of the present invention has the above-mentioned unit positioning mechanism. The first unit is a unit having an image carrier that carries an image. The second unit is a unit having a transfer roller that is in pressure contact with the image carrier. The image forming device conveys a sheet to a transfer roller gap formed between the image carrier and the transfer roller, and transfers the image to the sheet.

[0007] In the present invention, in the structure in which the rotation of the unit is restricted by the positioning member, it is possible to suppress a decrease in the disassembly property of the positioning member and its periphery, and to suppress positional deviation of the unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a perspective view of the image forming apparatus according to the embodiment. Figure 2 It was removed Figure 1A perspective view showing a state of a rear cover of the image forming apparatus shown. Figure 3 It is a schematic diagram showing the internal structure of the image forming apparatus according to the embodiment. Figure 4 It is a schematic diagram showing a configuration of an image forming section of the image forming apparatus according to the embodiment. Figure 5 It is a side view of a state in which a conveying unit is separated from a main body side unit of the image forming apparatus according to the embodiment. Figure 6 It is a side view of the conveying unit of the image forming apparatus according to the embodiment and a positioning member attached thereto. Figure 7 This is a perspective view of the transport unit and the positioning member attached to the transport unit of the image forming apparatus according to the embodiment, as viewed from the front. Figure 8 This is a perspective view of the transport unit and the positioning member attached to the transport unit of the image forming apparatus according to the embodiment, as viewed from the rear. Fig. 9 This is an enlarged perspective view of the periphery of a unit side portion in the transport unit of the image forming apparatus according to the embodiment. Fig.10 It is a side view of a positioning member of the image forming apparatus according to the embodiment and a torsion coil spring temporarily fixed thereto. Fig.11 It is a perspective view for explaining the installation process of the positioning member according to the embodiment. Fig.12 Yes Fig.11 A perspective view showing a state in which the positioning component is rotated to one side in the circumferential direction. Fig.13 It is a schematic diagram for explaining the installation process of the positioning member of the modification example. DETAILED DESCRIPTION

[0009] Below, refer to Figures 1 to 13 An image forming apparatus 100 according to an embodiment of the present invention and its modified example is described. In the following description, a color laser printer capable of printing an image on a sheet S is used as an example, but the present invention is not limited to printers and can also be applied to a multifunction printer having a copy function.

[0010] In the following description, a direction perpendicular to the flat ground on which the image forming apparatus 100 is installed is defined as a vertical direction and is denoted by reference symbol D. In addition, one of the horizontal directions perpendicular to the vertical direction D is denoted by reference symbol D1, and the other direction perpendicular to the direction D1 is denoted by reference symbol D2.

[0011] For example, one direction D1 is the width direction (left-right direction) of the image forming apparatus 100. In the following description, one direction D1 is referred to as the width direction D1. The width direction D1 is equivalent to the "prescribed direction". Another direction D2 is the front-back direction of the image forming apparatus 100. In the following description, another direction D2 is referred to as the front-back direction D2.

[0012] <Overall Structure of Image Forming Apparatus> The image forming apparatus 100 of this embodiment has Figure 1 and Figure 2 The image forming apparatus 100 has a main frame (reference numerals omitted). In addition, the image forming apparatus 100 has a rear cover CV. The main frame is covered by an exterior cover including the rear cover CV (reference numerals of other covers are omitted). Figure 2 In the figure, the rear cover CV is omitted and a portion of the device is shown.

[0013] The main frame supports the exterior cover. The main frame supports the rear cover CV so that it can rotate around an axis extending along the width direction D1. For example, the main frame has a rotation axis RA1 extending along the width direction D1 (see Figure 5 ). The rotation axis RA1 supports the lower end of the rear cover CV. The rear cover CV rotates with the rotation axis RA1 as a fulcrum so that the end on the opposite side to the side supported by the rotation axis RA1 (i.e., the upper end) swings. In other words, the rear cover CV is supported so as to be openable and closable relative to the main frame.

[0014] By opening the rear cover CV, the interior of the image forming apparatus 100 is exposed on one side (rear side) in the front-rear direction D2. By closing the rear cover CV, the interior of the image forming apparatus 100 is covered from one side in the front-rear direction D2. For example, when a sheet S jam occurs in the image forming apparatus 100, the rear cover CV is opened to remove the sheet S.

[0015] like Figure 3 As shown in FIG. 1 , the image forming apparatus 100 includes a main conveying path MP. The main conveying path MP passes through a transfer roller gap described later. Figure 3 In FIG. 1 , a main transport path MP is schematically indicated by a solid arrow, and a double-sided printing transport path DP described later is schematically indicated by a dotted arrow.

[0016] The image forming apparatus 100 also includes a sheet cassette CA. The sheet cassette CA stores sheets S used in a printing operation. The type of the sheets S is not particularly limited.

[0017] In a printing job, the image forming apparatus 100 supplies the sheet S in the sheet cassette CA to the main conveying path MP and conveys the sheet S along the main conveying path MP. Then, the image forming apparatus 100 prints an image on the conveyed sheet S. In other words, the image forming apparatus 100 includes a printing unit 1000 that prints an image on the conveyed sheet S.

[0018] The printing unit 1000 includes image forming units 110 for four colors, namely, cyan, magenta, yellow, and black. Each image forming unit 110 forms a toner image of a corresponding color. Hereinafter, the structure of a certain image forming unit 110 will be described. The basic structure of each image forming unit 110 is the same as each other. Therefore, the description of the structure of other image forming units 110 will be omitted by citing the following description.

[0019] like Figure 4 As shown, the image forming unit 110 includes a developing cartridge 200. The developing cartridge 200 stores toner of corresponding colors and performs a developing process using the toner. In addition, the image forming unit 110 includes a photosensitive drum 111 and a charging device 112. In addition, the image forming unit 100 includes one exposure unit 113 for the image forming unit 110 of four colors. In addition, the image forming unit 110 includes a cleaning device 114.

[0020] When the image forming unit 110 forms an image, the photosensitive drum 111 rotates. The charging device 112 charges the outer peripheral surface of the photosensitive drum 111. The exposure unit 113 exposes the outer peripheral surface of the photosensitive drum 111 to form an electrostatic latent image on the outer peripheral surface of the photosensitive drum 111. Then, the developing box 200 performs the following process as a developing process: toner is supplied to the outer peripheral surface of the photosensitive drum 111 to develop the electrostatic latent image into a toner image. In addition, the toner image on the outer peripheral surface of the photosensitive drum 111 is primarily transferred to the intermediate transfer belt 121 described later. The cleaning device 114 removes the toner that has not been transferred to the intermediate transfer belt 121 and remains on the outer peripheral surface of the photosensitive drum 111.

[0021] return Figure 3 The printing section 1000 includes a transfer belt unit 120 . In addition, the printing section 1000 includes a secondary transfer roller 130 .

[0022] The transfer belt unit 120 is disposed below each image forming unit 110. The transfer belt unit 120 includes an intermediate transfer belt 121. The intermediate transfer belt 121 is an endless belt.

[0023] The intermediate transfer belt 121 is stretched by a plurality of rollers including a driving roller 122 (the reference numerals of other rollers are omitted) and supported so as to be rotatable. The intermediate transfer belt 121 contacts the outer peripheral surface of the photosensitive drum 111 and rotates in this state. The driving roller 122 is rotated by power transmitted from a belt motor (not shown). The intermediate transfer belt 121 is driven to rotate by the rotation of the driving roller 122. The intermediate transfer belt 121 is equivalent to an "image carrier".

[0024] The transfer belt unit 120 includes a primary transfer roller 123. One primary transfer roller 123 is assigned to each color of cyan, magenta, yellow, and black. Each primary transfer roller 123 is arranged on the inner peripheral side of the intermediate transfer belt 121. Each primary transfer roller 123 is arranged opposite to the photosensitive drum 111 carrying the toner image of the corresponding color across the intermediate transfer belt 121.

[0025] The secondary transfer roller 130 is disposed opposite to the driving roller 122 with the intermediate transfer belt 121 interposed therebetween. The secondary transfer roller 130 is in pressure contact with the intermediate transfer belt 121. A transfer roller gap is formed between the secondary transfer roller 130 and the intermediate transfer belt 121. The secondary transfer roller 130 corresponds to a "transfer roller".

[0026] Each image forming unit 110 forms a toner image of a corresponding color. Each primary transfer roller 123 primarily transfers the toner image to the outer peripheral surface of the intermediate transfer belt 121. The intermediate transfer belt 121 rotates while carrying the toner image primarily transferred from each photosensitive drum 111 on its outer peripheral surface. When the sheet S passes through the transfer roller gap, the sheet S contacts the outer peripheral surface of the intermediate transfer belt 121. The secondary transfer roller 130 forms a transfer electric field between the secondary transfer roller 130 and the intermediate transfer belt 121, thereby secondarily transferring the toner image to the sheet S passing through the transfer roller gap.

[0027] The printing unit 1000 is provided with a fixing roller pair 140. The fixing roller pair 140 includes a heating roller and a pressure roller. The heating roller has a built-in heater. The pressure roller is in pressure contact with the heating roller, and a fixing roller gap is formed between the heating roller and the fixing roller pair 140, which holds the sheet S conveyed from the transfer roller gap and rotates. That is, the fixing roller pair 140 heats and presses the sheet S passing through the fixing roller gap. Thus, the fixing roller pair 140 fixes the toner image transferred to the sheet S on the sheet S. Thereafter, the sheet S is discharged to the discharge tray ET.

[0028] The image forming apparatus 100 can perform a duplex printing job for printing toner images on both sides of a sheet S, in addition to a single-sided printing job for printing a toner image on only one side of the sheet S. To perform the duplex printing job, the image forming apparatus 100 includes a duplex printing conveying path DP.

[0029] The duplex printing conveying path DP branches from the main conveying path MP downstream of the fixing roller nip in the sheet conveying direction, and merges with the main conveying path MP upstream of the transfer roller nip in the sheet conveying direction.

[0030] When the executed job is a single-sided printing job, the sheet S passes through the transfer roller nip only once, and the primary transfer process is performed on the sheet S passing through the transfer roller nip. Then, after the primary transfer process, the sheet S is directly discharged to the discharge tray ET.

[0031] When the job to be executed is a double-sided printing job, the sheet S passes through the transfer roller nip twice in order to perform a primary transfer process on each of the front and back sides of the sheet S. Specifically, when the sheet S passes through the transfer roller nip for the first time, the transfer process is performed on one side of the sheet S. After the first transfer process, after the rear end of the sheet S passes through the fixing roller nip and before the sheet S is completely discharged to the discharge tray ET, the sheet S is switched back. Thus, the sheet S is introduced into the double-sided printing conveying path DP from its rear end.

[0032] After that, the sheet S is conveyed along the double-sided printing conveying path DP. Then, the sheet S returns to the main conveying path MP from the upstream side of the transfer roller gap in the sheet conveying direction. The sheet S returned to the main conveying path MP passes through the transfer roller gap again. At this time, the direction of the front and back sides of the sheet S is reversed to the opposite direction compared to the last time it passed through the transfer roller gap. Therefore, when the sheet S passes through the transfer roller gap for the second time, the other side opposite to the one side of the sheet S is subjected to transfer processing.

[0033] <Units within the device> The image forming apparatus 100 includes a plurality of units, and some of the units will be described below.

[0034] like Figure 5 As shown in FIG. 1 , the image forming apparatus 100 includes a main body unit 1 and a transport unit 2. The main body unit 1 corresponds to a "first unit", and the transport unit 2 corresponds to a "second unit". Figure 5 , a state where the rear cover CV is slightly opened (a state where the transport unit 2 is separated from the main body side unit 1) is illustrated.

[0035] The main body side unit 1 is a unit having a transfer belt unit 120. That is, the main body side unit 1 has an intermediate transfer belt 121.

[0036] The conveying unit 2 is a unit that mainly carries out conveying of the sheet S. Figures 5 to 8 The transport unit 2 will be described.

[0037] The transport unit 2 has a unit side portion 20. The unit side portions 20 are disposed on one side and the other side in the width direction D1. The pair of unit side portions 20 face each other in the width direction D1.

[0038] The conveying unit 2 has a conveying guide G1 that defines a portion of the main conveying path MP. The conveying guide G1 is located between a pair of unit side portions 20 in the width direction D1. The conveying guide G1 defines a portion of the main conveying path MP together with conveying guides (not shown) of other units.

[0039] The conveying unit 2 has a conveying guide G2 that defines a portion of the duplex printing conveying path DP. The conveying guide G2 is located between the pair of unit side portions 20 in the width direction D1. The conveying guide G2 defines a portion of the duplex printing conveying path DP together with a conveying guide (reference numeral omitted) provided on the rear cover CV.

[0040] Here, the conveying unit 2 has a secondary transfer roller 130. However, the conveying unit 2 is a unit different from the main body side unit 1. In this structure, the conveying unit 2 is positioned relative to the main body side unit 1 so that a transfer nip is formed by the intermediate transfer belt 121 and the secondary transfer roller 130.

[0041] The conveying unit 2 is capable of rotating around an axis extending along the width direction D1. For example, the main frame has a rotation axis RA2 extending along the width direction D1. The rotation axis RA2 supports the end portion of the lower side of the conveying unit 2. The conveying unit 2 rotates with the rotation axis RA2 as a fulcrum so that the end portion on the opposite side to the side supported by the rotation axis RA2 (i.e., the end portion on the upper side) swings. The conveying unit 2 can be displaced between a first position and a second position by rotating around the axis of the rotation axis RA2.

[0042] The first position is a position where the conveying unit 2 is positioned relative to the main body-side unit 1 . Figure 6 The position of the conveying unit 2 shown is the first position. With the conveying unit 2 held in the first position (i.e., the conveying unit 2 is positioned relative to the main body side unit 1), the secondary transfer roller 130 is in pressure contact with the intermediate transfer belt 121. Thus, a transfer roller gap is formed between the intermediate transfer belt 121 and the secondary transfer roller 130.

[0043] The second position is a position other than the first position, and is a position where the transport unit 2 is not positioned relative to the main body side unit 1. When the transport unit 2 is located at the second position, the transport unit 2 cannot be positioned relative to the main body side unit 1. Figure 5 The position of the conveyor unit 2 shown is the second position.

[0044] When the conveying unit 2 is kept at the first position, a part of the main conveying path MP is formed by the conveying guide G1 of the conveying unit 2 and the conveying guides of other units. In addition, when the conveying unit 2 is kept at the first position and the rear cover CV is closed, a part of the double-sided printing conveying path DP is formed by the conveying guide G2 of the conveying unit 2 and the conveying guide of the rear cover CV (reference numerals omitted).

[0045] For example, when a paper jam occurs during the execution of a printing job, a paper jam handling operation is performed by opening the rear cover CV and rotating the conveying unit 2 to the second position. Since the double-sided printing conveying path DP is exposed by opening the rear cover CV, the sheet S stuck in the double-sided printing conveying path DP can be removed. Since the main conveying path MP is exposed by rotating the conveying unit 2 to the second position, the sheet S stuck in the main conveying path MP can be removed.

[0046] After the paper jam processing operation, the rear cover CV is closed. For example, the rear cover CV is rotated in the closing direction to push the conveying unit 2. Thus, the conveying unit 2 returns to the first position in synchronization with the closing of the rear cover CV.

[0047] In this configuration, the transport unit 2 must be normally held in the first position (eg, during the execution of a print job). If the transport unit 2 is displaced from the first position during the execution of a print job, image quality may be degraded or paper jam may occur.

[0048] Therefore, the image forming apparatus 100 includes a positioning member 3. The positioning member 3 positions the transport unit 2 relative to the main unit 1. In other words, the positioning member 3 holds the transport unit 2 at the first position. In other words, the positioning member 3 restricts the transport unit 2 from rotating from the first position to the second position.

[0049] <Unit Positioning> Below, refer to Fig. 9 and Fig.10 The structure of the positioning member 3 and its mounting structure with respect to the conveying unit 2 will be described.

[0050] The positioning member 3 is mounted one at each of the pair of unit side portions 20 in the conveying unit 2. The structure of the positioning member 3 and its mounting structure relative to the conveying unit 2 are the same on one side and the other side. Therefore, only one side will be described below, and the other side will be omitted by citing the following description.

[0051] The positioning member 3 is arranged outside the width direction D1 of the unit side portion 20. The secondary transfer roller 130 and the like are arranged inside the width direction D1 of the unit side portion 20. The outside of the width direction D1 is a direction from the center of the width direction D1 of the transport unit 2 toward one side or the other side of the width direction D1. The inside of the width direction D1 is a direction from one side or the other side of the width direction D1 of the transport unit 2 toward the center of the width direction D1.

[0052] The unit side portion 20 has a support shaft 21 for supporting the positioning member 3 on the outside in the width direction D1. The support shaft 21 protrudes outward from the unit side portion 20 in a cylindrical or cylindrical shape. When viewed from the width direction D1, the outer shape of the support shaft 21 is circular. For example, the unit side portion 20 is made of resin. In addition, the support shaft 21 is integrally molded with the unit side portion 20.

[0053] The positioning member 3 has a cylindrical portion 30. When the positioning member 3 is mounted on the unit side portion 20, the width direction D1 becomes the cylinder axis direction of the cylindrical portion 30. By inserting the support shaft 21 into the cylindrical portion 30, the positioning member 3 is mounted on the unit side portion 20. The cylindrical portion 30 is embedded in the support shaft 21 from the outside in the width direction D1. In the following description, the circumferential direction centered on the cylinder axis of the cylindrical portion 30 embedded in the support shaft 21 (i.e., the support shaft 21) when viewed from the width direction D1 is referred to as the circumferential direction.

[0054] The cylindrical portion 30 is slidable in the circumferential direction relative to the outer peripheral surface of the support shaft 21. That is, the support shaft 21 supports the positioning member 3 so as to be displaceable in the circumferential direction. In addition, the cylindrical portion 30 is also slidable in the width direction D1 relative to the outer peripheral surface of the support shaft 21.

[0055] The positioning member 3 has a hook portion 31. When viewed from the width direction D1, the hook portion 31 is arranged radially outward of the cylindrical portion 30. When viewed from the width direction D1, the hook portion 31 is a portion extending radially outward (i.e., away from the cylindrical portion 30) from the cylindrical portion 30, and is a hook-shaped portion that can be engaged with the boss portion 10 described later from one side in the circumferential direction. The hook portion 31 rotates around the cylinder axis of the cylindrical portion 30 as the cylindrical portion 30 is displaced in the circumferential direction.

[0056] In order to hold the transport unit 2 at the first position using the positioning member 3, the main body side unit 1 has a boss portion 10 protruding in the width direction D1 (see Figure 5 and Figure 6 ). When viewed from the width direction D1, the boss portion 10 is arranged on a rotation trajectory of the hook portion 31 when the hook portion 31 is rotated about the cylinder axis of the cylindrical portion 30 (ie, when the hook portion 31 is rotated in the circumferential direction).

[0057] The hook portion 31 engages with the boss portion 10 in a manner of circumferentially encircling the boss portion 10 from one side when the transport unit 2 is in the first position. Thus, the hook portion 31 restricts the transport unit 2 from rotating from the first position to the second position. As a result, the transport unit 2 is held in the first position. In other words, the transport unit 2 is positioned relative to the main body side unit 1.

[0058] However, the positioning member 3 is not fixed to the unit side portion 20 (i.e., the transport unit 2). That is, the positioning member 3 can be attached to and detached from the unit side portion 20. In this structure, if no countermeasures are taken, the cylindrical portion 30 may fall off the support shaft 21 and the positioning member 3 may fall off the unit side portion 20.

[0059] When the positioning member 3 is removed from the unit side portion 20 , the hook portion 31 is released from the boss portion 10 , and the transport unit 2 rotates from the first position to the second position.

[0060] In order to suppress such a malfunction, the unit side portion 20 has the restricting portion 23. In addition, the positioning member 3 has the restricted portion 32.

[0061] When viewed from the width direction D1, the restricted portion 32 is arranged radially outward of the cylindrical portion 30 and at a position different from the hook portion 31 in the circumferential direction. For example, when viewed from the width direction D1, the positioning member 3 has a portion 32a extending radially outward from the cylindrical portion 30, and has a protruding piece protruding from the portion 32a to one side in the circumferential direction as the restricted portion 32. In addition, the cylindrical portion 30 can be displaced in the circumferential direction. Therefore, the restricted portion 32 arranged radially outward of the cylindrical portion 30 can rotate around the cylinder axis of the cylindrical portion 30.

[0062] When viewed from the width direction D1, the restricting portion 23 is arranged at a predetermined position (hereinafter referred to as the restricting position) on the rotation trajectory of the restricted portion 32 rotating around the cylinder axis of the cylindrical portion 30. The restricted portion 32 is arranged at the restricting position by engaging the hook portion 31 with the boss portion 10 from one side in the circumferential direction. Thus, when the hook portion 31 is engaged with the boss portion 10 from one side in the circumferential direction, the restricting portion 23 overlaps with the restricted portion 32 from the outside in the width direction D1.

[0063] In a state where the restricting portion 23 overlaps the restricted portion 32 from the outside in the width direction D1, even if the restricted portion 32 (i.e., the positioning member 3) attempts to move to the outside in the width direction D1, the restricted portion 32 collides with the restricting portion 23. That is, the restricting portion 23 restricts the positioning member 3 from moving to the outside in the width direction D1. As a result, it is possible to suppress the positioning member 3 from falling off from the unit side portion 20.

[0064] However, when the positioning member 3 is displaced to the other side in the circumferential direction, the restricting portion 23 and the restricted portion 32 do not overlap in the width direction D1 . In this case, the positioning member 3 may fall off from the unit side portion 20 .

[0065] Therefore, the image forming apparatus 100 further includes a torsion coil spring 4. The torsion coil spring 4 is attached to the positioning member 3. The torsion coil spring 4 restricts displacement of the positioning member 3 to the other side in the circumferential direction by its biasing force.

[0066] The torsion coil spring 4 has a coil spring portion 40 (in other words, a helical portion). The coil spring portion 40 is inserted into the cylindrical portion 30 and arranged on the outer periphery of the cylindrical portion 30. In other words, the coil spring portion 40 is inserted into the cylindrical portion 30. By inserting the coil spring portion 40 into the cylindrical portion 30, the torsion coil spring 4 is attached to the positioning member 3.

[0067] The torsion coil spring 4 has a first arm 41 extending from one end of the coil spring portion 40 and a second arm 42 extending from the other end of the coil spring portion 40. The first arm 41 and the second arm 42 extend in the tangential direction of the coil spring portion 40 as viewed in the width direction D1.

[0068] The first arm portion 41 engages with the positioning member 3. Specifically, the positioning member 3 has a first engaging portion 33. The first engaging portion 33 is disposed radially outward of the cylindrical portion 30 as viewed in the width direction D1. The first arm portion 41 engages with the first engaging portion 33.

[0069] The second arm 42 engages with the transport unit 2. Specifically, the second engaging portion 22 is provided in the unit side portion 20. The edge of the opening 20a that passes through the unit side portion 20 in the width direction D1 functions as the second engaging portion 22. The second arm 42 engages with the second engaging portion 22.

[0070] The torsion coil spring 4 generates a force that applies the positioning member 3 to one side in the circumferential direction by engaging the first arm portion 41 with the first engaging portion 33 (i.e., the positioning member 3) and the second arm portion 42 with the second engaging portion 22 (i.e., the unit side portion 20). In other words, the torsion coil spring 4 applies the positioning member 3 to the direction in which the hook portion 31 engages with the boss portion 10 (i.e., one side in the circumferential direction). In other words, the torsion coil spring 4 restricts the positioning member 3 from being displaced to the other side in the circumferential direction.

[0071] In this embodiment, the positioning member 3 can be suppressed from being displaced to the other side in the circumferential direction. If the positioning member 3 does not displace to the other side in the circumferential direction, the overlapping of the limiting portion 23 and the restricted portion 32 in the width direction D1 is maintained, thereby suppressing the positioning member 3 from falling off from the unit side portion 20. As a result, the transport unit 2 can be suppressed from rotating from the first position to the second position. In other words, the transport unit 2 can be suppressed from being displaced relative to the main body side unit 1.

[0072] In the present embodiment, the torsion coil spring 4 is used to suppress the conveying unit 2 from rotating from the first position to the second position. By using the torsion coil spring 4, even if the positioning member 3 is not fixed to the unit side portion 20, the rotation of the conveying unit 2 (that is, the positional deviation of the conveying unit 2) can be reliably restricted by the positioning member 3. In other words, even if the positioning member 3 is not fixed to the unit side portion 20, it is possible to suppress the positioning member 3 from falling off from the unit side portion 20 due to the displacement of the positioning member 3 in the circumferential direction. In the case where the positioning member 3 is not fixed to the unit side portion 20, it is easy to disassemble the positioning member 3 and its surroundings (for example, remove the positioning member 3 from the unit side portion 20).

[0073] In the present embodiment, in the structure in which the rotation (i.e., positional deviation) of the conveying unit 2 is restricted by the positioning member 3, it is possible to suppress the decomposability of the positioning member 3 and its surroundings from being reduced, and to suppress the positional deviation of the conveying unit 2. When the positioning member 3 is removed from the conveying unit 2, it is sufficient to release the engagement between the second arm portion 42 of the torsion coil spring 4 and the second engaging portion 22 of the unit side portion 20 and rotate the positioning member 3 to the other side in the circumferential direction.

[0074] <Installation of positioning components> The positioning member 3 has a temporary fixing portion 34. The temporary fixing portion 34 can be engaged with the second arm portion 42 of the torsion coil spring 4. The temporary fixing portion 34 is used when the positioning member 3 is mounted on the unit side portion 20 (ie, the transport unit 2).

[0075] Below, refer to Fig.11 and Fig.12 A step of attaching the positioning member 3 to the unit side portion 20 will be described.

[0076] First, before the positioning member 3 is mounted on the unit side portion 20, the torsion coil spring 4 is mounted on the positioning member 3. At this time, the coil spring portion 40 is inserted into the cylindrical portion 30, and the first arm portion 41 is engaged with the first engaging portion 33. Furthermore, the second arm portion 42 is engaged with the temporary fixing portion 34. That is, the torsion coil spring 4 is temporarily fixed to the positioning member 3.

[0077] Next, the cylindrical portion 30 is inserted into the support shaft 21. At this time, the restricted portion 32 is kept so as not to overlap with the restricting portion 23 in the width direction D1, and in this state, the cylindrical portion 30 is inserted into the support shaft 21. Fig.11 The second arm portion 42 is kept engaged with the temporary fixing portion 34 until the cylindrical portion 30 is completely fitted into the support shaft 21 .

[0078] After the cylindrical portion 30 is inserted into the support shaft 21, the second arm portion 42 is moved from the temporary fixing portion 34 to the second engaging portion 22 (i.e., the unit side portion 20). At this time, the operator holds the second arm portion 42, removes the second arm portion 42 from the temporary fixing portion 34, and engages the second arm portion 42 with the second engaging portion 22.

[0079] When the coil spring portion 40 is inserted into the cylindrical portion 30 and the first arm portion 41 is engaged with the first engagement portion 33, the second arm portion 42 is engaged with the second engagement portion 22, and a force is generated in the torsion coil spring 4 to bias the positioning member 3 toward one side in the circumferential direction. Fig.12 The state shown is a state in which the restricted portion 32 and the restricting portion 23 overlap in the width direction D1.

[0080] In the present embodiment, by providing the temporary fixing portion 34 in the positioning member 3, the workability when installing the positioning member 3 on the unit side portion 20 is improved. Specifically, by embedding the coil spring portion 40 into the cylindrical portion 30, and engaging the first arm portion 41 with the first engaging portion 33 and engaging the second arm portion 42 with the temporary fixing portion 34, the torsion coil spring 4 is maintained in a state where force is applied in the torsion direction. Thus, during the installation operation of installing the positioning member 3 on the unit side portion 20 (specifically, before the cylindrical portion 30 is embedded in the support shaft 21), the torsion coil spring 4 can be prevented from falling off from the positioning member 3. For the operator, during the installation operation of installing the positioning member 3 on the unit side portion 20, there is no need to pay attention to the torsion coil spring 4 falling off, so the convenience is good.

[0081] As a modified example, the following configuration may be used. Fig.13 Modifications will be described.

[0082] In the modified example, the transport unit 2 has a guide portion 24. The guide portion 24 is disposed inside the width direction D1 of the unit side portion 20. In addition, the guide portion 24 has an inclined surface 240 that rises from the outside toward the inside in the width direction D1.

[0083] The inclined surface 240 is arranged on the moving path of the front end of the second arm portion 42 (specifically, the front end of the second arm portion 42 on the opposite side of the connection side with the coil spring portion 40) when the cylindrical portion 30 is inserted into the support shaft 21. Specifically, when the cylindrical portion 30 is inserted into the support shaft 21 in a state where the second arm portion 42 is engaged with the temporary fixing portion 34, the front end of the second arm portion 42 reaches the inclined surface 240 of the guide portion 24 arranged on the inner side of the width direction D1 of the unit side portion 20 via the second engaging portion 22 (that is, the opening 20a that penetrates the unit side portion 20 in the width direction D1) from the outside of the width direction D1 of the unit side portion 20. In other words, the second arm portion 42 contacts the inclined surface 240. Thereafter, the second arm portion 42 moves along the inclined surface 240.

[0084] As the second arm portion 42 moves along the inclined surface 240, the position of the front end of the second arm portion 42 in the vertical direction is displaced upward. In other words, the second arm portion 42 is displaced to a position above the position where it can engage with the temporary fixing portion 34. As a result, the engagement between the second arm portion 42 and the temporary fixing portion 34 is released. Then, the second arm portion 42 that has left the temporary fixing portion 34 engages with the second engaging portion 22 (i.e., the edge of the opening 20a of the unit side portion 20).

[0085] In the modified example, by fitting the cylindrical portion 30 into the support shaft 21, the second arm portion 42 is re-engaged from the temporary fixing portion 34 to the second engaging portion 22 even without performing the operation of re-engaging the second arm portion 42 from the temporary fixing portion 34 to the second engaging portion 22. Since it is unnecessary to perform the operation of re-engaging the second arm portion 42 from the temporary fixing portion 34 to the second engaging portion 22 separately, the convenience of the operator is improved.

[0086] The embodiments disclosed herein are illustrative in all aspects and should not be construed as restrictive. The scope of the present invention is indicated by the claims rather than the description of the embodiments described above, and includes all modifications within the scope of the claims and the meaning equivalent to the claims.

Claims

1. A unit positioning mechanism, characterized in that: include: A first unit having a boss portion; A second unit that is displaceable between a first position positioned relative to the first unit and a second position other than the first position by rotating about an axis extending in a predetermined direction; as well as a positioning member to hold the second unit in the first position, The positioning component has: The cylindrical portion has the specified direction as the cylindrical axis direction; The hook portion is arranged radially outward of the cylindrical portion when viewed from the specified direction, and is engaged with the boss portion in a manner of surrounding the boss portion from one side in a circumferential direction centered on the cylinder axis of the cylindrical portion; as well as The restricted portion is arranged radially outward of the cylindrical portion and at a position different from that of the hook portion in the circumferential direction when viewed from the prescribed direction. The second unit has: Unit side; A support shaft protrudes from the side of the unit toward the outside of the specified direction, into which the cylindrical portion is inserted from the outside of the specified direction, and supports the positioning member so as to be displaceable in the circumferential direction; as well as The restricting portion is arranged on a rotation trajectory of the restricted portion rotating around the cylinder axis of the cylindrical portion as viewed from the prescribed direction, The hook portion engages with the boss portion when the second unit is located at the first position, thereby restricting the second unit from rotating from the first position to the second position. The restricting portion overlaps the restricted portion from the outside of the predetermined direction when the hook portion is engaged with the boss portion, thereby restricting the positioning member from moving outward in the predetermined direction. The unit positioning mechanism includes a torsion coil spring, and the torsion coil spring includes: a coil spring portion disposed on the cylindrical portion; A first arm portion extends from one end of the coil spring portion; and a second arm portion extends from the other end of the coil spring portion, The torsion coil spring applies force to the positioning member in a direction in which the hook portion is engaged with the boss portion, through the first arm portion being engaged with the positioning member and the second arm portion being engaged with the unit side portion.

2. The unit positioning mechanism according to claim 1, characterized in that: The positioning member includes a temporary fixing portion that can be engaged with the second arm portion.

3. The unit positioning mechanism according to claim 2, characterized in that: The unit side portion has an edge portion of an opening penetrating in the predetermined direction as an engaging portion for engaging with the second arm portion. The second unit has an inclined surface, which is arranged on the inner side of the predetermined direction of the side portion of the unit and rises from the outer side to the inner side of the predetermined direction. When the cylindrical portion is inserted into the supporting shaft with the second arm portion engaged with the temporary fixing portion, the second arm portion reaches the inclined surface through the opening, and the second arm portion moves along the inclined surface, so that the engagement between the second arm portion and the temporary fixing portion is released, and the second arm portion engages with the edge of the opening.

4. An image forming device, characterized in that: The image forming apparatus comprises the unit positioning mechanism according to any one of claims 1 to 3, The first unit is a unit having an image carrier carrying an image, The second unit is a unit having a transfer roller in pressure contact with the image carrier. The image forming device conveys a sheet to a transfer roller nip formed between the image carrier and the transfer roller, and transfers the image onto the sheet.

Images