Unit positioning mechanism and image forming apparatus

Abstract

The invention provides a unit positioning mechanism and an image forming apparatus. The cover is rotated in the closing direction to start pressing the unit-side receiving portion by the first pressing portion, the hook portion is in contact with the boss portion to displace the positioning member to the other side in the circumferential direction, and after the contact point of the hook portion with respect to the boss portion passes through the lowest point of the boss portion, the second pressing portion is started to press the hook-side receiving portion. Before the cover reaches the closed position, the unit-side receiving portion is separated from the first pressing portion, and when the cover continues to rotate in the closing direction, one of the second pressing portion and the hook-side receiving portion elastically deforms in a direction away from the other, the second pressing portion crosses the hook-side receiving portion, and the second pressing portion crosses the hook-side receiving portion. The pressing of the second pressing part on the hook-side receiving part is released.

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 rear cover and a transport unit that rotates in conjunction with the opening and closing of the rear cover. The transport unit rotates in one direction in conjunction with the closing of the rear cover and reaches a position positioned relative to the main body side unit.

[0003] In the past, the transport unit was kept in a state of pressure contact with the main body side unit. As a result, the transport unit received a reaction force from the main body side unit, and the reaction force was sometimes applied to the rear cover. In this case, in order to suppress the deformation of the rear cover caused by the reaction force from the main body side unit, it is necessary to increase the rigidity of the rear cover by adding ribs to the rear cover or thickening the rear cover itself. As a result, the image forming apparatus becomes larger in size. Summary of the invention

[0004] The present invention has been made to solve the above-mentioned problems, and an object thereof is to provide a unit positioning mechanism and an image forming apparatus that can position a unit while suppressing the size of an apparatus including the unit in a structure in which the unit is positioned by rotating the unit in conjunction with the opening and closing of a cover.

[0005] In order to achieve the above-mentioned purpose, the unit positioning mechanism of the first aspect of the present invention includes: a cover, which can be displaced between a closed position covering the inside of a main frame from one side of a second direction orthogonal to the first direction and the horizontal direction and a position other than the closed position, namely, an open position, by rotating around the axis of a first rotating axis extending along a first direction orthogonal to the up-down direction; a first unit, which is installed inside the main frame and has a boss portion; a second unit, which is arranged in a direction from the open position toward the closed position, namely, on the downstream side of the closing direction, relative to the cover, and can be displaced between a first position positioned relative to the first unit and a position other than the first position, namely, a second position, by rotating around the axis of a second rotating axis extending parallel to the first rotating axis at a position above the first rotating axis and on the other side opposite to the first side of the second direction; a positioning component, which is installed on the second unit to keep the second unit in the first position; and a torsion coil spring, which is installed on the positioning component. The positioning component comprises: a cylindrical portion, with the first direction being the cylinder axis direction; and a hook portion, which is arranged radially outward of the cylindrical portion when viewed from the first direction, and can be engaged with the boss portion in a manner of embracing the boss portion from one side in the circumferential direction centered on the cylinder axis of the cylindrical portion, and is engaged with the boss portion when the second unit is located at the first position, thereby limiting the second unit from rotating from the first position to the second position. The second unit comprises a support shaft, in which the cylindrical portion is embedded, and the support shaft supports the positioning component so as to be displaceable in the circumferential direction. The torsion coil spring applies force to the positioning component in the direction in which the hook portion engages with the boss portion, i.e., one side in the circumferential direction. The cover comprises a first pressing portion and a second pressing portion. The second unit comprises a unit side bearing portion that receives pressure from the first pressing portion. The positioning component comprises a hook side bearing portion that receives pressure from the second pressing portion. By rotating the cover from the open position to the closed direction, the first pressing portion starts pressing the unit side bearing portion, so that the second unit rotates to the first position. After the first pressing part starts pressing the unit side bearing part, the front end of the hook part contacts the boss part, and the positioning part is displaced to the other side of the circumferential direction in the direction of overcoming the force of the torsion coil spring. After the contact point of the front end of the hook part relative to the boss part passes through the lowest point of the boss part when viewed from the first direction, the second pressing part contacts the hook side bearing part from one side in the circumferential direction, and the second pressing part starts pressing the hook side bearing part to displace the positioning part to one side in the circumferential direction, and the hook part is engaged with the boss part by the displacement of the positioning part to one side in the circumferential direction. After the cover starts rotating in the closing direction, before the cover reaches the closed position, the positions of the first rotation axis and the second rotation axis when viewed from the first direction are different from each other, so that the unit side bearing part is separated from the first pressing part.After the displacement of the positioning component to one side in the circumferential direction is stopped by the engagement of the hook portion with the boss portion, the cover continues to rotate in the closing direction, and one of the second pressing portion and the hook side supporting portion elastically deforms in the direction away from the other side, the second pressing portion passes over the hook side supporting portion, and the pressure of the second pressing portion on the hook side supporting portion is released.

[0006] The image forming device of the second aspect of the present invention is provided with 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. By keeping the second unit in the first position, the image carrier and the transfer roller are in pressure contact with each other to form a transfer roller gap between the image carrier and the transfer roller. The image forming device conveys a sheet to the transfer roller gap and transfers the image onto the sheet.

[0007] According to the present invention, in a structure in which the unit is positioned by rotating the unit in conjunction with the opening and closing of the cover, the unit can be positioned while suppressing an increase in the size of a device including 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 1 A 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.11It 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 diagram showing the positional relationship between the first rotation axis and the second rotation axis of the image forming apparatus according to the embodiment. Fig.14 It is a diagram showing the positional relationship between the boss portion and the hook portion of the image forming apparatus according to the embodiment. Fig.15 This is a diagram showing a state at the time when the second pressing portion of the image forming apparatus according to the embodiment starts pressing the hook-side receiving portion. Fig.16 It is a diagram showing the shapes of the second pressing portion and the hook-side receiving portion of the image forming apparatus according to the embodiment. Fig.17 This is a diagram showing a state in which the first pressing portion of the image forming apparatus according to the embodiment releases the pressing of the unit-side receiving portion. Fig.18 It is a diagram showing a state transition when the pressing of the hook-side receiving portion by the second pressing portion of the image forming apparatus according to the embodiment is released. DETAILED DESCRIPTION

[0009] Below, refer to Figures 1 to 18 An image forming apparatus 100 according to an embodiment of the present invention will be described. In the following description, a color laser printer capable of printing an image on a sheet S is taken as an example, but the present invention is not limited to printers and may also be applied to a multifunction peripheral 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 "first 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. The front-back direction is equivalent to the "second direction".

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

[0013] The main frame FR supports the exterior cover. The main frame FR supports the rear cover CV so that it can rotate around an axis extending along the width direction D1. Specifically, the main frame FR has a first rotation axis RA1 extending along the width direction D1 (see Figure 5 ). The first rotation axis RA1 supports the lower end of the rear cover CV. The rear cover CV rotates with the first rotation axis RA1 as a fulcrum so that the end on the opposite side to the side supported by the first 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 FR.

[0014] The rear cover CV can be displaced between a closed position covering the inside of the main frame FR from the rear (i.e., the outside) of one side of the front-to-back direction D2 and an open position other than the closed position by rotating around the axis of the first rotation axis RA1. By opening the rear cover CV, the inside of the main frame FR is exposed from the rear. By closing the rear cover CV, the inside of the main frame FR is covered from the rear. For example, when a sheet S is jammed during the execution of a printing operation, the rear cover CV is opened to remove the sheet S.

[0015] Figure 1 The position of the rear cover CV shown is the closed position. At least a conveying unit 2 (see FIG. 2 ) described later is installed inside the main frame FR. Figure 2 ). By opening the rear cover CV, the conveying unit 2 is exposed at the rear.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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 .

[0023] 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.

[0024] 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".

[0025] 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.

[0026] 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".

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] <Units within the device> The image forming apparatus 100 includes a plurality of units, and some of the units will be described below.

[0035] 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.

[0036] The main body side unit 1 is mounted inside the main body frame FR. 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] The conveying unit 2 is capable of rotating around an axis extending along the width direction D1. Specifically, the main frame FR has a second rotating axis RA2 extending along the width direction D1. The second rotating axis RA2 extends parallel to the first rotating axis RA1. The second rotating axis RA2 supports the end portion on the lower side of the conveying unit 2. The conveying unit 2 rotates with the second rotating axis RA2 as a fulcrum so that the end portion on the opposite side to the side supported by the second rotating 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 second rotating axis RA2.

[0043] The first position is a position where the conveyance unit 2 is positioned relative to the main body side unit 1 inside the main body frame FR. 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.

[0044] The second position is a position other than the first position, where the transport unit 2 is not positioned relative to the main body 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 unit 1.

[0045] 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.

[0046] For example, when a sheet S jams during the execution of a printing job, a 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 jammed 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 jammed in the main conveying path MP can be removed.

[0047] After the paper jam processing operation, the rear cover CV is closed. By closing the rear cover CV, the conveying unit 2 is pushed by the rear cover CV. Thus, the conveying unit 2 returns to the first position in synchronization with the closing of the rear cover CV.

[0048] 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.

[0049] 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.

[0050] <Unit Positioning> Below, refer to Figures 9 to 12 The structure of the positioning member 3 and its mounting structure with respect to the conveying unit 2 will be described.

[0051] The positioning member 3 is a hook that can be engaged with other members. One positioning member 3 is mounted on each of the pair of unit side portions 20 in the conveying unit 2. The structure of the positioning member 3 and the mounting structure thereof with respect 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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).

[0058] 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 located at 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 at the first position. That is, the transport unit 2 is positioned relative to the main body side unit 1.

[0059] However, the positioning member 3 is not fixed to the unit side portion 20 (ie, the transport unit 2), but 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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 .

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] Thus, the positioning member 3 can be prevented 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 preventing the positioning member 3 from falling off from the unit side portion 20. As a result, the transport unit 2 can be prevented from rotating from the first position to the second position. That is, the transport unit 2 can be prevented from being displaced relative to the main body side unit 1.

[0073] When the positioning member 3 is mounted on the unit side portion 20, the second arm portion 42 is engaged with the temporary fixing portion 34 (see Fig.10 ). And, if Fig.11 As shown in FIG. 1 , the cylindrical portion 30 is inserted into the support shaft 21 in a state where the restricting portion 23 and the restricted portion 32 do not overlap in the width direction D1. Fig.12 As shown, the positioning member 3 is displaced to one side in the circumferential direction. Fig.12 Although not shown in the figure, the second arm portion 42 is relocated from the temporary fixing portion 34 to the second engaging portion 22 .

[0074] <Rotation of Conveying Unit to First Position> By opening and closing the rear cover CV, the transport unit 2 rotates in synchronization with the opening and closing of the rear cover CV, and the transport unit 2 is displaced between the first position and the second position.

[0075] In the following description, the rotation direction of the back cover CV when rotating the back cover CV from the open position to the closed position is simply referred to as the closing direction. In addition, the rotation direction of the back cover CV when rotating the back cover CV from the closed position to the open position is simply referred to as the opening direction.

[0076] The rear cover CV and the conveying unit 2 are configured as follows Figure 5 In addition, Figure 5 The position of the rear cover CV shown is the open position. Figure 5 In the embodiment, the counterclockwise direction with the first rotation axis RA1 as the center is the closing direction, and the clockwise direction is the opening direction. Figure 5 The position of the conveyor unit 2 shown is the second position.

[0077] The conveying unit 2 is arranged on the downstream side of the closing direction relative to the rear cover CV. In addition, when viewed from the width direction D1, the second rotation axis RA2 supporting the conveying unit 2 is located above the first rotation axis RA1 supporting the rear cover CV. Furthermore, when viewed from the width direction D1, the second rotation axis RA2 is located in front of the first rotation axis RA1 (i.e., on the other side opposite to the one side in the front-rear direction D2).

[0078] Thus, when the conveying unit 2 is in the second position, when the rear cover CV is rotated from the open position to the closed position, the conveying unit 2 is pressed by the rear cover CV and rotates from the second position to the first position. That is, the displacement of the conveying unit 2 between the first position and the second position can be synchronized with the opening and closing of the rear cover CV.

[0079] The rear cover CV has a first pressing portion 101 for pressing the conveying unit 2 and a second pressing portion 102 for pressing the positioning member 3. The conveying unit 2 has a unit-side receiving portion 24 pressed by the first pressing portion 101. The positioning member 3 has a hook-side receiving portion 35 pressed by the second pressing portion 102.

[0080] When viewed in the width direction D1, the first pressing portion 101 is disposed closer to the first rotation axis RA1 than the second pressing portion 102. That is, when viewed in the width direction D1, the second pressing portion 102 is disposed farther from the first rotation axis RA1 than the first pressing portion 101.

[0081] When the rear cover CV is in the open position and the conveying unit 2 is in the second position, Fig.13 As shown, the first pressing portion 101 contacts the unit side receiving portion 24. Thus, when the rear cover CV is in the open position and the conveying unit 2 is in the second position, the rear cover CV is rotated from the open position to the closed direction, and the first pressing portion 101 starts to press the unit side receiving portion 24, so that the conveying unit 2 is rotated from the second position to the first position. Fig.13 In order to facilitate the observation of the drawings, the positioning component 3 is omitted.

[0082] After the first pressing portion 101 starts pressing the unit-side receiving portion 24 (that is, during the rotation of the transport unit 2 from the second position to the first position), Fig.14 As shown in FIG. 1 , the positioning member 3 is displaced in the circumferential direction by the front end 31a of the hook portion 31 contacting the boss portion 10. In the initial stage, the outer portion of the front end 31a of the hook portion 31 opposite to the inner portion engaged with the boss portion 10 contacts the boss portion 10. Therefore, in the initial stage, the hook portion 31 is not engaged with the boss portion 10 (see FIG. 1 ). Fig.14 ).

[0083] From the state where the outer portion of the front end 31a of the hook portion 31 contacts the boss portion 10, the rear cover CV is further rotated from the open position to the closed direction (i.e., the conveying unit 2 is rotated from the second position to the first position), and the positioning member 3 is displaced to the other side of the circumferential direction in the direction of overcoming the force of the torsion coil spring 4 while the outer portion of the front end 31a of the hook portion 31 contacts the boss portion 10. Thereafter, the positioning member 3 is displaced to one side of the circumferential direction.

[0084] Specifically, if Fig.14 As shown in the figure above, first, the outer portion of the front end 31a of the hook portion 31 contacts the portion of the boss portion 10 on one side in the front-rear direction D2 (hereinafter referred to as the one side portion of the boss portion 10). Then, the front end 31a of the hook portion 31 moves from the one side portion of the boss portion 10 and passes the lowest point P. Then, as shown in FIG. Fig.14 As shown in the following figure, the front end 31a of the hook portion 31 reaches the portion of the boss portion 10 on the other side opposite to the one side in the front-rear direction D2 (hereinafter referred to as the other side portion of the boss portion 10). At this time, the inner side portion of the front end 31a of the hook portion 31 contacts the other side portion of the boss portion 10. As a result, the hook portion 31 is engaged with the boss portion 10.

[0085] In addition, the boss portion 10 has: a first portion 10a, which is a portion on the upper side of the boss portion 10; and a second portion 10b, which is a portion located on the lower side of the first portion 10a. When viewed from the width direction D1, the first portion 10a has an arc-shaped outer periphery that protrudes toward the upper side. When viewed from the width direction D1, the second portion 10b is a shape that gradually tapers downward from the first portion 10a (i.e., a roughly triangular shape). The second portion 10b protrudes from the first portion 10a in a gradually tapering manner downward. In other words, the second portion 10b is a V-shaped portion that protrudes downward from the first portion 10a in a side view. In this structure, the front end position of the lower side of the second portion 10b in the boss portion 10 becomes the lowest point P.

[0086] After the contact point of the front end 31a of the hook portion 31 with respect to the boss portion 10 passes through the lowest point P of the boss portion 10, as shown in FIG. Fig.15 As shown, the second pressing portion 102 contacts the hook-side receiving portion 35 from one side in the circumferential direction, thereby starting to press the hook-side receiving portion 35 by the second pressing portion 102 to displace the positioning member 3 to one side in the circumferential direction. Fig.15 In the figure, the conveying unit 2 is indicated by a dotted line for easy viewing of the drawing.

[0087] The second pressing portion 102 and the hook-side receiving portion 35 have Fig.16 The second pressing portion 102 includes a cover-side arm 1021 and a cover-side protrusion 1022 protruding from the cover-side arm 1021 in the width direction D1. The hook-side receiving portion 35 includes a hook-side arm 351 and a hook-side protrusion 352 protruding from the hook-side arm 351 in the width direction D1.

[0088] The cover-side protrusion 1022 contacts the hook-side protrusion 352 from the other side opposite to the one side in the circumferential direction, and the cover-side protrusion 1022 presses the hook-side protrusion 352 from the other side in the circumferential direction to the one side. That is, the pressing portion of the second pressing portion 102 that actually presses the hook-side receiving portion 35 is the cover-side protrusion 1022. The pressed portion of the hook-side receiving portion 35 that is actually pressed by the second pressing portion 102 is the hook-side protrusion 352. Fig.16 In the figure, "Out" indicates the outside of the width direction D1, and "In" indicates the inside of the width direction D1. Fig.16 In FIG. 1 , the arrow D3 indicates the pressing direction in which the second pressing portion 102 presses the hook-side receiving portion 35 by rotating the rear cover CV in the closing direction. Fig.18 Same here.

[0089] When the front end 31a of the hook 31 passes the lowest point P of the boss 10, the second pressing portion 102 presses the hook side receiving portion 35, and the positioning member 3 is displaced to one side in the circumferential direction. As a result, the hook 31 is engaged with the boss 10, and the positioning member 3 is displaced to one side in the circumferential direction. Fig.14 The state shown in the figure below. After the hook portion 31 is engaged with the boss portion 10, the torsion coil spring 4 applies force to the positioning component 3 so that the positioning component 3 is displaced to one side in the circumferential direction, thereby maintaining the engagement of the hook portion 31 with the boss portion 10. In addition, the displacement of the positioning component 3 to one side in the circumferential direction is stopped by the engagement of the hook portion 31 with the boss portion 10. After the hook portion 31 is engaged with the boss portion 10, even if the rear cover CV continues to rotate in the closing direction, that is, even if the second pressing portion 102 continues to press the hook side bearing portion 35, the positioning component 3 does not displace to one side in the circumferential direction.

[0090] Here, the positions of the first rotation axis RA1 and the second rotation axis RA2 when viewed from the width direction D1 are different from each other. Fig.13 As shown, when viewed from the width direction D1, the rotation trajectory T2 of the unit-side receiving portion 24 rotating about the second rotation axis RA2 is offset from the rotation trajectory T1 of the first pressing portion 101 rotating about the first rotation axis RA1.

[0091] Thus, after the rear cover CV starts to rotate in the closing direction and before the rear cover CV reaches the closed position, Fig.17 As shown in FIG. 1 , the first pressing portion 101 is released from pressing the unit side receiving portion 24. The first pressing portion 101 and the unit side receiving portion 24 rotate while separating from each other. Fig.17 In order to facilitate the observation of the drawings, the positioning component 3 is omitted.

[0092] In addition, after the displacement of the positioning member 3 to one side in the circumferential direction is stopped by the engagement of the hook portion 31 with the boss portion 10, the rear cover CV continues to rotate in the closing direction, as shown in FIG. Fig.18 As shown, one of the second pressing portion 102 and the hook-side receiving portion 35 is elastically deformed in a direction away from the other. For example, the second pressing portion 102 and the hook-side receiving portion 35 are both made of elastically deformable resin. Therefore, when one of the second pressing portion 102 and the hook-side receiving portion 35 is elastically deformed in a direction away from the other, the other may also be elastically deformed in a direction away from the one. That is, both the second pressing portion 102 and the hook-side receiving portion 35 may be elastically deformed in a direction away from each other.

[0093] Before the hook portion 31 is engaged with the boss portion 10, the cover-side protrusion 1022 is located on the other side opposite to the one side in the circumferential direction with respect to the hook-side protrusion 352 (see Fig.16 ). As a result, the positioning member 3 is pressed and displaced to one side in the circumferential direction.

[0094] After the displacement of the positioning member 3 to one side in the circumferential direction stops due to the engagement of the hook portion 31 with the boss portion 10, when the rear cover CV continues to rotate in the closing direction, one of the second pressing portion 102 and the hook side receiving portion 35 is elastically deformed in a direction away from the other (see Fig.18 As a result, the second pressing portion 102 passes over the hook-side receiving portion 35, and the second pressing portion 102 reaches one side in the circumferential direction relative to the hook-side receiving portion 35 (see Fig.18 Specifically, the cover-side protrusion 1022 passes over the hook-side protrusion 352, and the cover-side protrusion 1022 reaches one side in the circumferential direction relative to the hook-side protrusion 352. As a result, the pressing of the second pressing portion 102 on the hook-side receiving portion 35 is released.

[0095] In this embodiment, until the hook portion 31 and the boss portion 10 are engaged, that is, until the secondary transfer roller 130 (i.e., the conveying unit 2) and the intermediate transfer belt 121 on the driving roller 122 (i.e., the main body side unit 1) are properly pressed in contact, if the rear cover CV is further rotated in the closing direction, the pressing of the hook side receiving portion 35 by the second pressing portion 102 is released. At this moment, the pressing of the unit side receiving portion 24 by the first pressing portion 101 has been released. That is, in the state where the secondary transfer roller 130 and the intermediate transfer belt 121 on the driving roller 122 are properly pressed in contact, the rear cover CV does not press the conveying unit 2.

[0096] Thus, when the conveying unit 2 is maintained at the first position and the rear cover CV is maintained at the closed position, no pressing force is applied to the rear cover CV from the conveying unit 2. In addition, when the conveying unit 2 is maintained at the first position, even if the rear cover CV does not press the conveying unit 2, the hook portion 31 is engaged with the boss portion 10, so that the secondary transfer roller 130 is maintained in a state of pressure contact with the intermediate transfer belt 121 on the drive roller 122.

[0097] If the conveying unit 2 is kept in the first position by continuously pressing the conveying unit 2 by the rear cover CV, an undesirable situation may occur in which the rear cover CV is deformed due to the pressing force applied to the rear cover CV. In order to suppress the occurrence of this undesirable situation, countermeasures such as increasing the rigidity of the rear cover CV must be taken. For example, countermeasures such as thickening the rear cover CV or adding ribs to the rear cover CV are required. When such countermeasures are taken, the image forming apparatus 100 is enlarged.

[0098] On the other hand, in this embodiment, even if the rear cover CV does not continuously press the conveying unit 2, the conveying unit 2 can be held at the first position. Therefore, it is not necessary to increase the rigidity of the rear cover CV. As a result, the conveying unit 2 can be positioned without increasing the size of the image forming apparatus 100.

[0099] Here, in this embodiment, when viewed from the width direction D1, the front end position of the lower side of the second portion 10b in the boss portion 10 is eccentric to one side (i.e., rearward) in the front-rear direction D2 relative to the center position of the circle including the outer periphery of the first portion 10a. Therefore, when the rear cover CV presses the conveying unit 2 to rotate the conveying unit 2, the front end 31a of the hook portion 31 quickly passes through the lowest point P.

[0100] After the front end 31a of the hook portion 31 passes the lowest point P, the positioning member 3 tends to be displaced to one side in the circumferential direction due to the force of the torsion coil spring 4. In other words, after the front end 31a of the hook portion 31 passes the lowest point P, a force is generated again to rotate the conveying unit 2 toward the first position. Thus, the force for closing the rear cover CV can be reduced.

[0101] <Rotation of Conveying Unit to Second Position> When the rear cover CV is in the closed position and the conveying unit 2 is maintained in the first position (i.e., the hook portion 31 is engaged with the boss portion 10), the cover-side protrusion 1022 of the second pressing portion 102 is located on one side in the circumferential direction relative to the hook-side protrusion 352 of the hook-side receiving portion 35. In this state, if the rear cover CV is rotated from the closed position to the open direction, the cover-side protrusion 1022 is engaged with the hook-side protrusion 352 from one side in the circumferential direction.

[0102] Then, if the rear cover CV is further rotated in the opening direction, the cover-side protrusion 1022 of the second pressing portion 102 presses the hook-side protrusion 352 of the hook-side receiving portion 35 from one circumferential direction. As a result, the positioning member 3 overcomes the biasing force of the torsion coil spring 4 and displaces to the other circumferential direction.

[0103] As the positioning member 3 is displaced to the other side in the circumferential direction, the front end 31a of the hook portion 31 reaches the lowest point P and passes over the lowest point P. That is, the front end 31a of the hook portion 31 passes through the lowest point P from the other side portion of the boss portion 10 to the one side portion of the boss portion 10. As a result, the engagement of the hook portion 31 with respect to the boss portion 10 is released.

[0104] In this embodiment, by rotating the rear cover CV from the closed position to the open position, the positioning of the transport unit 2 relative to the main body unit 1 by the positioning member 3 is released, and the transport unit 2 can be rotated from the first position to the second position. From the operator's perspective, since the transport unit 2 can be brought to the second position by simply opening the rear cover CV, the convenience is good.

[0105] 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: The cover is displaceable between a closed position covering the inside of the main frame from one side in a second direction orthogonal to the first direction and the horizontal direction and a position other than the closed position, i.e., an open position, by rotating about an axis of a first rotation axis extending in a first direction orthogonal to the up-down direction; A first unit is installed inside the main frame and has a boss portion; The second unit is arranged on the downstream side of the closing direction from the open position toward the closed position relative to the cover, and is capable of being 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 of a second rotation axis extending parallel to the first rotation axis at a position above the first rotation axis and at a position on the other side opposite to the first direction than the first rotation axis; a positioning component, mounted on the second unit, to keep the second unit at the first position; and A torsion coil spring is mounted on the positioning component. The positioning component has: A cylindrical portion, wherein the first direction is the cylindrical axis direction; as well as The hook portion is arranged radially outward of the cylindrical portion when viewed from the first direction, and can engage 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, and restricts the second unit from rotating from the first position to the second position by engaging with the boss portion when the second unit is located at the first position. The second unit includes a support shaft into which the cylindrical portion is inserted and supports the positioning member so as to be displaceable in the circumferential direction. The torsion coil spring applies force to the positioning member in the direction in which the hook portion engages with the boss portion, that is, in one side of the circumferential direction. The cover has a first pressing portion and a second pressing portion, The second unit has a unit-side receiving portion that receives pressure from the first pressing portion. The positioning member includes a hook-side receiving portion that receives pressure from the second pressing portion. When the cover is rotated from the open position to the closed direction, the first pressing portion starts pressing the unit-side receiving portion to rotate the second unit to the first position. After the first pressing portion starts pressing the unit-side bearing portion, the front end of the hook portion contacts the boss portion, and the positioning member is displaced in the direction of overcoming the force of the torsion coil spring, that is, in the other side of the circumferential direction. After the contact point of the front end of the hook portion with respect to the boss portion passes through the lowest point of the boss portion when viewed from the first direction, the second pressing portion contacts the hook-side receiving portion from one side in the circumferential direction, and the second pressing portion starts pressing the hook-side receiving portion to displace the positioning member to one side in the circumferential direction, and the hook portion is engaged with the boss portion by the displacement of the positioning member to one side in the circumferential direction. After the cover starts to rotate in the closing direction and before the cover reaches the closed position, the positions of the first rotation axis and the second rotation axis when viewed from the first direction are different from each other, whereby the unit-side receiving portion is separated from the first pressing portion. After the displacement of the positioning component to one side in the circumferential direction is stopped by the engagement of the hook portion with the boss portion, the cover continues to rotate in the closing direction, and one of the second pressing portion and the hook side supporting portion is elastically deformed in a direction away from the other, and the second pressing portion passes over the hook side supporting portion, and the pressure of the second pressing portion on the hook side supporting portion is released.

2. The unit positioning mechanism according to claim 1, characterized in that: When viewed from the first direction, the boss portion has: The first part has an arc-shaped outer circumference; as well as The second V-shaped portion, viewed from the side, protrudes downward from the first portion. The front end position of the second portion in the boss portion is the lowest point, The front end position of the second portion is offset to one side in the second direction relative to the center position of a circle including the outer periphery of the first portion.

3. The unit positioning mechanism according to claim 1, characterized in that: When the cover rotates from the closed position to the open position, the second pressing portion presses the hook side supporting portion from one side in the circumferential direction so that the positioning component overcomes the force of the torsion coil spring and moves to the other side in the circumferential direction, thereby releasing the engagement of the hook portion with respect to the boss portion.

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 that carries an image, The second unit is a unit having a transfer roller, By keeping the second unit at the first position, the image carrier and the transfer roller are brought into pressure contact with each other to form a transfer roller gap between the image carrier and the transfer roller. The image forming device conveys a sheet to the transfer roller nip and transfers the image onto the sheet.

Images