Image forming device

Abstract

An image formation device (100) comprises a unit (30) that can be attached to and detached from a body frame (101), and a lock mechanism (40). The lock mechanism (40) has a grip part (37) that can move reciprocally in the attachment direction and the detachment direction of the unit (30), a lock member (41) that is swingably positioned in the unit (30) and has a hook part (41b) capable of engaging with an engagement-receiving part (50) formed on the body frame (101), and a first biasing member (43) that biases the lock member (41) in a first direction, in which the hook part (41b) engages with the engagement-receiving part (50). Due to the grip part (37) being moved in the detachment direction, the lock member (41) swings in a second direction that is the opposite of the first direction, in opposition to the biasing force of the first biasing member (43), and the engagement of the hook part (41) and the engagement-receiving part (50) is released. The lock member (41) has a restriction part (41e) that restricts the swinging of the lock member (41) in the second direction while the grip part (37) is not moved in the detachment direction.

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus provided with a unit such as an intermediate transfer unit that is detachable from the main body of the apparatus. [Background technology]

[0002] Various image forming apparatuses have been proposed, including an intermediate transfer type image forming apparatus. An intermediate transfer type image forming apparatus includes an endless intermediate transfer belt that rotates in a predetermined direction and multiple image forming units arranged along the intermediate transfer belt. Each image forming unit sequentially superimposes toner images on the intermediate transfer belt, and then transfers the images onto a recording medium all at once.

[0003] In the image forming apparatus using the intermediate transfer method described above, the intermediate transfer belt, which has a shorter service life than the device body, needs to be replaced periodically. Therefore, a configuration in which the intermediate transfer unit including the intermediate transfer belt is detachable from the image forming apparatus body is widely used. In this case, the intermediate transfer unit can be fixed to the image forming apparatus body by operating a rotating lever or by fixing with screws.

[0004] For example, Patent Document 1 discloses an image forming device that has a handle member attached to one end of a rotating shaft and a locking member attached to the other end of the rotating shaft, and the unit is locked to the device main body by the locking member rotating in accordance with the rotation of the handle member.

[0005] Patent Document 2 discloses an image forming apparatus equipped with a unit that can be inserted and removed horizontally from a main frame, and a locking mechanism for the unit. The locking mechanism has a locking member and a biasing member. The locking member is arranged on the unit side so as to be able to move back and forth in a direction perpendicular to the insertion and removal direction, and has an engaging protrusion that can engage with an engaged portion on the main frame side. The biasing member biases the locking member in a first direction in which the engaging protrusion engages with the engaged portion. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-147977 [Patent Document 2] Japanese Patent Application Laid-Open No. 2017-194490 Summary of the Invention [Problem to be solved by the invention]

[0007] In conventional methods, the rotation of the locking member is restricted solely by the biasing force of a spring (biasing member). However, if the image forming apparatus is subjected to an impact due to vibration during transportation or being dropped, depending on the magnitude of the impact, the biasing force of the spring alone may not be enough to restrict the rotation of the locking member, and the locked state may be released. On the other hand, if the spring load is increased to make it more difficult to rotate the locking member, there is a problem that it becomes difficult to remove the intermediate transfer unit, leading to a decrease in ease of replacement.

[0008] Although the above description has been given taking as an example the case where the intermediate transfer unit is attached to and detached from the main body of the apparatus, the same problems exist when other units are attached to and detached from the main body of the apparatus.

[0009] In view of the above problems, an object of the present invention is to provide an image forming apparatus that can reliably maintain a state in which a unit that is detachable from the apparatus main body is locked to the apparatus main body, and that can also maintain the detachability of the unit. [Means for solving the problem]

[0010] To achieve the above object, a first aspect of the present invention provides an image forming apparatus including a unit detachable from a main frame and a locking mechanism that holds the unit attached to the main frame and releases the hold. The locking mechanism includes a handle, a locking member, and a first biasing member. The handle is disposed on the unit and is reciprocally movable in the unit attachment and removal directions. The locking member is swingably disposed on the unit and has a hook that can engage with an engagement portion formed on the main frame. The first biasing member biases the locking member in a first direction in which the hook engages with the engagement portion. By moving the handle in the removal direction, the locking member swings in a second direction opposite to the first direction against the biasing force of the first biasing member, disengaging the hook from the engagement portion and enabling removal of the unit from the main frame. The locking member has a restricting portion that restricts the locking member from swinging in the second direction while preventing the handle from moving in the removal direction. [Effects of the Invention]

[0011] According to the first configuration of the present invention, the direction in which the handle is operated to release the locking mechanism and the direction in which the unit is removed are the same, allowing the locking mechanism to be released and the unit to be removed simultaneously. Therefore, the user can unlock the unit from the main frame with a simple operation without tightening screws or operating a rotary lever, facilitating the unit replacement process. Furthermore, when the handle is not moved in the removal direction, the restricting protrusion restricts the locking member from swinging in the second direction, eliminating the risk of the locking member and the engaged portion becoming disengaged due to vibration or impact. This effectively prevents the unit from rattling or falling off the main frame due to vibration or dropping during transportation. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic cross-sectional view showing the internal configuration of an image forming apparatus 100 according to an embodiment of the present invention. [Figure 2]FIG. 1 is a perspective view of the intermediate transfer unit 30 as seen from the belt cleaning unit 19 side. [Figure 3] 3 is a side view showing a state in which a cover member 38 is removed from a connecting frame 32 of the intermediate transfer unit 30. [Figure 4] FIG. 4 is a perspective view of the first handle 37 as seen from the rear side of FIG. [Figure 5] FIG. 10 is a perspective view of a lock member 41 disposed inside the cover member 38. [Figure 6] FIG. 4 is an enlarged view of the locking mechanism 40 in FIG. 3, showing a state in which the locking member 41 and the engaged portion 50 are engaged with each other. [Figure 7] 7 is a diagram showing a state in which the locking member 41 has been swung in a direction away from the engaged portion 50 without the first handle portion 37 being pulled up from the state shown in FIG. [Figure 8] 7 is a diagram showing a state in which the first handle portion 37 is pulled up from the state of FIG. 6 and the locking member 41 is swung in a direction away from the engaged portion 50. FIG. [Figure 9] 1 is a side view showing a state in which the intermediate transfer unit 30 is attached to the main body frame 101. [Figure 10] 1 is a side view showing a state immediately before the intermediate transfer unit 30 is removed from the main body frame 101. [Figure 11] FIG. 10 is a cross-sectional perspective view of the first handle portion 37, showing a state in which the restricting member 51 is placed in the restricting position. [Figure 12] 12 is a side cross-sectional view of the first handle portion 37 in FIG. 11. [Figure 13] FIG. 12 is a diagram showing a state in which the regulating member 51 is moved from the state of FIG. 11 to the release position. [Figure 14] A side cross-sectional view of the first handle portion 37 in FIG. 13 [Figure 15] FIG. 15 is a diagram showing a state in which the first handle portion 37 is pulled up from the state of FIG. 14. [Figure 16] FIG. 10 is a perspective view of the locking mechanism 40, showing how the locking member 41 swings when the first handle portion 37 is pulled up. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic side view showing the internal configuration of an image forming apparatus 100 according to one embodiment of the present invention. The image forming apparatus 100 shown in FIG. 1 is a so-called tandem color printer, and has the following configuration. Four image forming units Pa, Pb, Pc, and Pd are arranged within the main body of the image forming apparatus 100 in this order from the upstream side in the transport direction (the front side of the apparatus, the left side in FIG. 1). These image forming units Pa to Pd are provided corresponding to images of four different colors (magenta, cyan, yellow, and black), and sequentially form magenta, cyan, yellow, and black images through the respective processes of charging, exposure, development, and transfer.

[0014] Each of the image forming stations Pa to Pd is provided with photosensitive drums 1a, 1b, 1c, and 1d, each carrying a visible image (toner image) of each color. An endless intermediate transfer belt 8, which rotates counterclockwise in FIG. 1, is provided adjacent to each of the image forming stations Pa to Pd. The toner images formed on the photosensitive drums 1a to 1d are sequentially transferred onto the intermediate transfer belt 8, which moves while contacting the photosensitive drums 1a to 1d, and then transferred all at once onto a sheet of paper S, an example of a recording medium, by a secondary transfer roller 9. The images are then fixed onto the sheet of paper S by a fixing unit 13, and then ejected from the image forming apparatus 100. While the photosensitive drums 1a to 1d are rotating clockwise in FIG. 1, an image formation process is performed on each of the photosensitive drums 1a to 1d.

[0015] The paper S onto which the toner image is transferred is stored in a paper cassette 16 at the bottom of the main body of the image forming apparatus 100. The paper S is transported to the secondary transfer roller 9 via a paper feed roller 12a and a pair of registration rollers 12b.

[0016] Next, the image forming units Pa to Pd will be described. Charging devices 2a to 2d, developing devices 3a to 3d, and cleaning devices 7a to 7d are arranged around the photosensitive drums 1a to 1d in the drum rotation direction (clockwise in FIG. 1), and primary transfer rollers 6a to 6d are arranged across the intermediate transfer belt 8. Furthermore, a belt cleaning unit 19 is arranged upstream of the image forming unit Pa in the rotation direction of the intermediate transfer belt 8, facing the tension roller 11 with the intermediate transfer belt 8 in between. The belt cleaning unit 19 removes toner remaining on the surface of the intermediate transfer belt 8.

[0017] Next, the image formation procedure in the image forming apparatus 100 will be described. When a user inputs a command to start image formation, first, the main motor (not shown) starts rotating the photosensitive drums 1a-1d. Then, the surfaces of the photosensitive drums 1a-1d are uniformly charged by the charging devices 2a-2d. Next, the surfaces of the photosensitive drums 1a-1d are irradiated with beams of light (laser light) emitted from the exposure device 5, and electrostatic latent images corresponding to image signals are formed on each of the photosensitive drums 1a-1d.

[0018] The developing devices 3a-3d are filled with a predetermined amount of magenta, cyan, yellow, and black toner, respectively. When the toner content in the two-component developer filled in each developing device 3a-3d falls below a predetermined value due to the formation of a toner image (described later), toner is replenished from toner containers 4a-4d to each developing device 3a-3d. The toner in the developer is supplied to the photosensitive drums 1a-1d by the developing devices 3a-3d and electrostatically adheres to them. This forms a toner image corresponding to the electrostatic latent image formed by exposure from the exposure device 5.

[0019] Then, primary transfer rollers 6a-6d apply an electric field at a predetermined transfer voltage between the primary transfer rollers 6a-6d and the photosensitive drums 1a-1d. As a result, the magenta, cyan, yellow, and black toner images on the photosensitive drums 1a-1d are primarily transferred onto the intermediate transfer belt 8. These four color images are formed in a predetermined positional relationship for forming a predetermined full-color image. Thereafter, in preparation for the subsequent formation of a new electrostatic latent image, any toner remaining on the surfaces of the photosensitive drums 1a-1d is removed by cleaning devices 7a-7d.

[0020] As the drive roller 10 is rotated by a belt drive motor (not shown), the intermediate transfer belt 8 begins to rotate counterclockwise. As the intermediate transfer belt 8 rotates, the paper S is transported from the pair of registration rollers 12b to a secondary transfer roller 9 provided adjacent to the intermediate transfer belt 8 at a predetermined timing, and a full-color image is transferred onto the paper S. The paper S onto which the toner image has been transferred is transported to the fixing unit 13. Any toner remaining on the surface of the intermediate transfer belt 8 is removed by a belt cleaning unit 19.

[0021] The paper S transported to the fixing unit 13 is heated and pressurized by the fixing roller pair 13a, and the toner image is fixed to the surface of the paper S, forming a predetermined full-color image. The paper S on which the full-color image has been formed has its transport direction diverted by the branching unit 14, which branches in multiple directions, and is discharged directly (or after being sent to the double-sided transport path 18 and printed on both sides) by the discharge roller pair 15 onto the discharge tray 17.

[0022] FIG. 2 is an external perspective view of the intermediate transfer unit 30, seen from the belt cleaning unit 19 side. As shown in FIG. 2, the intermediate transfer unit 30 has a pair of side frames 31a and 31b, a connecting frame 32, and an upper frame 33. The side frames 31a and 31b rotatably support a plurality of suspension rollers, including the drive roller 10, the tension roller 11, and the primary transfer rollers 6a to 6d. Bushings (bearing members) 35 are attached to both ends of the rotation shaft of the drive roller 10. The bushings 35 fit into positioning portions 101a (see FIG. 9) of the main body frame 101 when the intermediate transfer unit 30 is attached to the image forming apparatus 100.

[0023] The connecting frame 32 is fixed to one end (the front right side in FIG. 2) of the side frames 31a and 31b in a bridging manner. A first handle portion 37 is provided on the upper part of the connecting frame 32, and a pair of cover members 38 are attached to the left and right of the first handle portion 37.

[0024] The top frame 33 is fixed to the upper parts of the side frames 31a, 31a in a bridging manner. The top frame 33 is provided with container placement portions 33a to 33d on which the toner containers 4a to 4d (see FIG. 1) are placed, and a second handle portion 39.

[0025] FIG. 3 is a side view showing the intermediate transfer unit 30 with the cover member 38 removed from the connecting frame 32, and shows the intermediate transfer unit 30 attached to the image forming apparatus 100. FIG. 4 is an external perspective view of the first handle portion 37 as seen from the rear side of FIG. 3, and FIG. 5 is a perspective view of a locking member 41 disposed inside the cover member 38. The locking mechanism 40 of the intermediate transfer unit 30 will be described in detail using FIGS. 3 to 5. Note that in the following drawings, the removal direction of the intermediate transfer unit 30 on the connecting frame 32 side is indicated by arrow A, and the attachment direction is indicated by arrow A'.

[0026] 3, the connecting frame 32 is provided with a locking mechanism 40 that holds the intermediate transfer unit 30 in an attached state relative to the main body frame 101 (see FIG. 9) and can release the hold. The locking mechanism 40 includes a first handle portion 37, a locking member 41, and a first compression spring 43. The locking member 41 and the first compression spring 43 are provided in pairs on the left and right sides of the first handle portion 37.

[0027] 4, the first handle portion 37 has a grip portion 37a, a protruding portion 37b, and a guide rib 37c. The protruding portion 37b protrudes from the lower portion of the first handle portion 37. A pair of guide ribs 37c are formed on the left and right side surfaces of the first handle portion 37 and extend in the vertical direction along the side surface of the first handle portion 37. The guide ribs 37c engage with rail grooves (not shown) of the connecting frame 32, thereby supporting the first handle portion 37 so that it can reciprocate in the vertical direction relative to the connecting frame 32.

[0028] 5, the locking member 41 has a boss portion 41a, a hook portion 41b, an arm portion 41c, a spring holding protrusion 41d, and a restricting protrusion 41e. The boss portion 41a is rotatably fitted onto a support shaft 32a (see FIG. 3) formed on the connecting frame 32. The hook portion 41b extends radially from the boss portion 41a and is engageable with an engaged portion 50 (see FIG. 3) on the main body frame 101 side.

[0029] The arm portion 41c extends from the boss portion 41a in a different direction from the hook portion 41b (substantially perpendicular to the hook portion 41b) and faces the protrusion 37b (see FIG. 4) of the first handle portion 37 from above. The spring holding protrusion 41d protrudes in the same direction as the arm portion 41c, with the back side of the hook portion 41b as its base end and its diameter decreasing toward its tip end. The outer diameter (maximum diameter) of the base end of the spring holding protrusion 41d is substantially the same as the inner diameter of the first compression spring 43. The restricting protrusion 41e protrudes from the back side of the hook portion 41b in the same direction as the arm portion 41c. The restricting protrusion 41e is formed between the arm portion 41c and the spring holding protrusion 41d, and is located closer to the spring holding protrusion 41d.

[0030] One end of the first compression spring 43 is held by the spring holding protrusion 41d of the locking member 41, and the other end is held by a spring holding portion (not shown) of the connecting frame 32. The first compression spring 43 biases the locking member 41 in a direction (first direction) in which the hook portion 41b engages with the engaged portion 50.

[0031] Next, an operation for releasing the locking mechanism 40 of the intermediate transfer unit 30 relative to the main body frame 101 will be described. Fig. 6 is an enlarged view of the locking mechanism 40 in Fig. 3, showing the state in which the locking member 41 and the engaged portion 50 are engaged. Below, the locking mechanism 40 on the right side of the first handle portion 37 will be described, but the locking mechanism 40 on the left side of the first handle portion 37 will be described in exactly the same way, except that it is symmetrical.

[0032] As shown in Figure 6, when the intermediate transfer unit 30 is attached to the main body frame 101, the hook portion 41b of the locking member 41 engages with the engaged portion 50. The locking member 41 is biased by the first compression spring 43 in a direction approaching the engaged portion 50 (first direction, counterclockwise in Figure 6). This maintains the engaged state between the locking member 41 and the engaged portion 50, and prevents the intermediate transfer unit 30 from being removed.

[0033] Furthermore, the arm portion 41c of the locking member 41 faces the upper surface of the protruding portion 37b of the first handle portion 37 from above (from the upstream side in the mounting direction of the intermediate transfer unit 30). The restricting protrusion 41e of the locking member 41 is disposed to the side of the protruding portion 37b.

[0034] 7 is a diagram showing a state in which the locking member 41 has swung from the state in FIG. 6 in a direction away from the engaged portion 50 without pulling up the first handle portion 37. When the locking member 41 swung in a direction away from the engaged portion 50 (the second direction, the clockwise direction in FIG. 7) due to vibration or impact being applied to the intermediate transfer unit 30, the restricting protrusion 41e comes into contact with the side surface of the protruding portion 37b, as shown in FIG.

[0035] As a result, the rocking of the locking member 41 is restricted, and the engagement state between the hook portion 41b of the locking member 41 and the engaged portion 50 is maintained. This effectively prevents the intermediate transfer unit 30 from rattling or falling off from the main body frame 101 due to disengagement between the locking member 41 and the engaged portion 50.

[0036] 8 is a diagram showing a state in which the first handle portion 37 is pulled up from the state in FIG. 6 and the locking member 41 is swung in a direction away from the engaged portion 50. To release the locking mechanism 40 of the intermediate transfer unit 30, the grip portion 37a of the first handle portion 37 is gripped and the first handle portion 37 is pulled up (in the direction of arrow A).

[0037] 8, the protrusion 37b of the first handle 37 pushes up the arm 41c of the locking member 41, causing the locking member 41 to swing in the clockwise direction (second direction). As a result, the hook 41b swings in a direction away from the engaged portion 50 while compressing the first compression spring 43, disengaging the hook 41b from the engaged portion 50 and allowing the intermediate transfer unit 30 to be removed.

[0038] When the locking member 41 swings in the second direction, the restricting protrusion 41e approaches the protruding portion 37b, but the protruding portion 37b rises while pushing up the arm portion 41c. As a result, as shown in Fig. 8, the restricting protrusion 41e enters below the protruding portion 37b (upstream in the moving direction of the protruding portion 37b), so there is no risk that the restricting protrusion 41e will interfere with unlocking.

[0039] 9 is a side view showing a state in which the intermediate transfer unit 30 is attached to the main body frame 101. FIG. 10 is a side view showing a state immediately before the intermediate transfer unit 30 is removed from the main body frame 101.

[0040] When removing the intermediate transfer unit 30 from the main body frame 101, first, open the open / close cover 17a that constitutes the discharge tray 17 (see FIG. 1), and remove the toner containers 4a to 4d (see FIG. 1) to obtain the state shown in FIG. 9. Next, with the first handle 37 pulled up, the end of the intermediate transfer unit 30 on the front side of the device (left side in FIG. 10) is lifted upward (the removal direction, arrow A direction). Then, when the end of the intermediate transfer unit 30 on the front side of the device has been lifted to a predetermined angle, the second handle 39 is grasped together with the first handle 37, and the bush 35 (see FIG. 2) on the rear side of the intermediate transfer unit 30 (right side in FIG. 10) is pulled out from the positioning portion 101a and toward the front side of the device, completing the removal of the intermediate transfer unit 30.

[0041] When mounting the intermediate transfer unit 30 to the main body frame 101, first, with the front side of the intermediate transfer unit 30 raised as shown in Fig. 10, the bushing 35 on the rear side of the device is fitted into the positioning portion 101a. Then, the front side of the intermediate transfer unit 30 is gradually lowered downward (mounting direction, arrow A' direction).

[0042] As the front side of the intermediate transfer unit 30 is lowered, the locking member 41 approaches the engaged portion 50 on the main body frame 101. At this time, because the first handle portion 37 is pulled up, the arm portion 41c of the locking member 41 is pushed up by the protrusion 37b, and the locking member 41 is maintained in a state of swinging in the second direction (the position shown in FIG. 8). Therefore, the hook portion 41b descends without coming into contact with the engaged portion 50.

[0043] When the front side of the intermediate transfer unit 30 is lowered to a predetermined position, the hook portion 41b descends to a position beyond the lower end of the engaged portion 50 (see FIG. 8). When the first handle portion 37 is released in this state, the first handle portion 37 descends under its own weight. As a result, the protrusion portion 37b also descends, and the locking member 47 swings in the first direction due to the biasing force of the first compression spring 43.

[0044] 6, the hook portion 41b and the engaged portion 50 are engaged with each other, thereby restricting removal of the intermediate transfer unit 30. In this manner, the attachment of the intermediate transfer unit 30 to the main body frame 101 is completed.

[0045] According to the above configuration, when removing the intermediate transfer unit 30 from the image forming apparatus 100, the locking member 41 can be disengaged from the engaged portion 50 simply by grasping and pulling up the first handle portion 37. Furthermore, because the direction in which the first handle portion 37 is operated to release the locking mechanism 40 and the direction in which the intermediate transfer unit 30 is removed are the same (upward), the locking mechanism 40 can be released and the intermediate transfer unit 30 can be removed simultaneously. Therefore, the user can release the locking mechanism 40 of the intermediate transfer unit 30 with a simple operation without having to fasten screws or operate a rotary lever, and the replacement work of the intermediate transfer unit 30 can be carried out smoothly.

[0046] Furthermore, when the intermediate transfer unit 30 is attached to the image forming apparatus 100, the hook portion 41b of the locking member 41 engages with the engagement portion 50 of the main body frame 101 simply by inserting the intermediate transfer unit 30. Therefore, the intermediate transfer unit 30 can be automatically locked to the main body frame 101 using the locking mechanism 40 without any special operation.

[0047] Furthermore, when the first handle portion 37 is not pulled up, the restricting protrusion 41e restricts the rocking of the locking member 41, so there is no risk of the locking member 41 and the engaged portion 50 becoming disengaged due to vibration or impact. Therefore, rattling of the intermediate transfer unit 30 or falling off of the main body frame 101 due to vibration or dropping during transportation can be effectively prevented.

[0048] As described above, unless the first handle portion 37 is pulled up, the locking member 41 does not swing and the intermediate transfer unit 30 is not unlocked. However, if the first handle portion 37 is unintentionally moved upward, there is a risk that the engagement between the locking member 41 and the engaged portion 50 will be released due to vibration or impact. Therefore, in this embodiment, a restricting member 51 is provided to restrict the movement of the first handle portion 37.

[0049] Fig. 11 is a cross-sectional perspective view of the first handle portion 37 (cross-sectional view taken along the arrow XX' in Fig. 3), showing a state in which the restricting member 51 is placed in the restricting position. Fig. 12 is a side cross-sectional view of the first handle portion 37 in Fig. 11. As shown in Figs. 11 and 12, the restricting member 51 is placed on the holding portion 37d of the first handle portion 37.

[0050] The restricting member 51 is a plate-like member having a predetermined length in the extension direction of the first handle portion 37 (a direction perpendicular to the plane of the paper in FIG. 12). The restricting member 51 is formed with a spring accommodating portion 51a that is open on the side opposite the connecting frame 32 (the left side in FIG. 12). A second compression spring 53 is disposed within the spring accommodating portion 51a, and the restricting member 51 is biased by the second compression spring 53 in a direction approaching the connecting frame 32 (the protruding direction). An inclined surface 51b that slopes upward from the upstream side to the downstream side in the protruding direction is formed on the end of the restricting member 51 on the connecting frame 32 side.

[0051] In the state in which the locking member 41 and the engaged portion 50 are engaged (see FIG. 6), the restricting member 51 protrudes to a position (restricted position) overlapping below the flange portion 32b formed at the upper end of the connecting frame 32 due to the biasing force of the second compression spring 53, as shown in FIG. 12. Therefore, the interference between the restricting member 51 and the flange portion 32b restricts the upward movement of the first handle portion 37. This makes it possible to prevent the first handle portion 37 from unintentionally moving upward and thereby releasing the engagement between the locking member 41 and the engaged portion 50.

[0052] Fig. 13 is a diagram showing a state in which the restricting member 51 has been moved from the state shown in Fig. 11 to the release position. Fig. 14 is a side cross-sectional view of the first handle portion 37 shown in Fig. 13. When releasing the engagement between the locking member 41 and the engaged portion 50, as shown in Figs. 13 and 14, a tool such as a screwdriver (not shown) is inserted into the operation hole 55 formed in the flange portion 32b, and the restricting member 51 is moved in a direction away from the connecting frame 32 (in the direction of arrow B) against the biasing force of the second compression spring 53 until it is positioned so as not to overlap with the flange portion 32b (release position). This allows the first handle portion 37 to move upward.

[0053] Fig. 15 is a diagram showing a state in which the first handle portion 37 has been pulled up from the state shown in Fig. 14. Fig. 16 is a diagram showing how the locking member 41 swings when the first handle portion 37 is pulled up. With the restricting member 51 held in the release position by a jig, pulling up the first handle portion 37 as shown in Fig. 15 causes the protrusion 37b to push up the arm portion 41c of the locking member 41 as shown in Fig. 16, and the locking member 41 swings in the second direction with the support shaft 32a as the fulcrum. This releases the engagement between the hook portion 41b and the engaged portion 50 (see Fig. 8), allowing the intermediate transfer unit 30 to be removed.

[0054] After the tip of the regulating member 51 passes through the flange portion 32b, it is no longer necessary to hold it in the released position with a jig. After passing through the flange portion 32b, the regulating member 51 protrudes so as to overlap above the flange portion 32b due to the biasing force of the second compression spring 53, as shown in FIG.

[0055] When engaging the hook portion 41b with the engaged portion 50, the first handle portion 37 is moved downward so that the inclined surface 51b of the restricting member 51 abuts against the tip of the flange portion 32b (see FIG. 15).

[0056] When the first handle portion 37 is moved further downward, the inclined surface 51b receives a reaction force from the flange portion 32b. Because the restricting member 51 can move horizontally within the holding portion 37d, the horizontal (leftward in FIG. 15) component of the reaction force received from the flange portion 32b causes the restricting member 51 to move in a direction away from the flange portion 32b (in the direction of arrow B) against the biasing force of the second compression spring 53.

[0057] Thereafter, the inclined surface 51b descends while abutting against the tip of the flange portion 32b. When the inclined surface 51b overcomes the tip of the flange portion 32b, the resisting force from the flange portion 32b is eliminated, and the restricting member 51 moves in a direction approaching the connecting frame 32 due to the biasing force of the second compression spring 53. As a result, as shown in FIG. 12, the restricting member 51 protrudes so as to overlap below the flange portion 32b, and the upward movement of the first handle portion 37 is restricted.

[0058] The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present invention. For example, in the above-described embodiment, the intermediate transfer unit 30 is configured to be attached and detached by vertically raising and lowering one end thereof with the other end thereof as a fulcrum. However, the intermediate transfer unit 30 may be configured to be inserted and removed horizontally from the main body of the image forming apparatus 100. Furthermore, the present invention can be applied to units other than the intermediate transfer unit 30 as long as they are detachable from the main body of the image forming apparatus 100.

[0059] Furthermore, in the above embodiment, the intermediate transfer unit 30 is inserted into the main body frame 101 with the first handle portion 37 pulled upward to swing the locking member 41 in the second direction, thereby avoiding contact between the hook portion 41b and the engaged portion 50. Instead of this configuration, an inclined surface may be formed on the engaged portion 50 or the hook portion 41b, and the locking member 41 may be swung in the second direction so that the hook portion 41b and the engaged portion 50 come into contact at the inclined surface when the intermediate transfer unit 30 is inserted.

[0060] In the above embodiment, the regulating member 51 is moved to the release position using the inclined surface 51b formed on the regulating member 51, but an inclined surface may also be formed on the upper surface of the flange portion 32b at a position where the regulating member 51 comes into contact. Also, an inclined surface may be formed on both the regulating member 51 and the flange portion 32b.

[0061] Furthermore, the present invention is not limited to tandem color printers such as those shown in FIG. 1, but can also be applied to various image forming devices that have units that can be attached to or detached from the image forming device 100 main body, such as monochrome copiers, digital multifunction machines, facsimiles, and laser printers. [Industrial Applicability]

[0062] The present invention can be used in an image forming apparatus equipped with a unit that is detachable from the apparatus main body. By using the present invention, it is possible to provide an image forming apparatus that can reliably maintain a state in which the detachable unit is locked to the apparatus main body and maintain the detachability of the unit.

Claims

1. A unit that is detachable from the main body frame; a locking mechanism that holds the unit in a mounted state on the main body frame and can release the holding; Equipped with The locking mechanism is a handle portion disposed on the unit and reciprocally movable in a direction in which the unit is attached and detached; a locking member that is swingably disposed on the unit and has a hook portion that can engage with an engaged portion formed on the main body frame; a first biasing member that biases the locking member in a first direction in which the hook portion engages with the engaged portion, By moving the handle portion in the removal direction, the locking member swings in a second direction opposite to the first direction against the biasing force of the first biasing member, and the engagement between the hook portion and the engaged portion is released, making it possible to remove the unit from the main body frame. the locking member has a regulating portion that regulates the swinging of the locking member in the second direction while preventing the handle portion from moving in the removal direction, and maintains the engaged state between the hook portion and the engaged portion.

2. The handle portion has a pair of protrusions protruding from the left and right side surfaces, a pair of locking members are arranged on the left and right of the handle portion, and each of the locking members has a boss portion that rotatably engages with a support shaft formed on the unit, a hook portion that extends radially from the boss portion, and an arm portion that extends from the boss portion in a direction different from that of the hook portion and contacts the protrusion from the upstream side in the installation direction, By moving the handle portion in the removal direction, the protrusion presses the arm portion in the removal direction against the biasing force of the first biasing member, causing the locking member to swing in the second direction, and the engagement between the hook portion and the engaged portion is released.

2. The image forming apparatus according to claim 1, wherein the regulating portion is a regulating protrusion that protrudes from the rear side of the hook portion of the locking member in the same direction as the arm portion, and when the locking member swings in the second direction without moving the handle portion in the removal direction, the regulating protrusion comes into contact with the protruding portion to regulate the swinging of the locking member.

3. 3. The image forming apparatus according to claim 2, wherein when the handle portion is moved in the removal direction, the regulating protrusion enters upstream of the movement direction of the protruding portion as the locking member swings in the second direction, thereby avoiding contact with the protruding portion.

4. 2. The image forming apparatus according to claim 1, further comprising a restricting member selectively positioned at a restricting position that restricts movement of the handle portion in the removal direction and at a release position that allows movement of the handle portion in the removal direction.

5. The unit has a pair of side frames and a connecting frame that is connected to one end of the side frames in a bridging manner and is provided with the locking mechanism, and is detachable by raising and lowering the connecting frame side relative to the main frame, 5. The image forming apparatus according to claim 4, wherein the regulating member is movable between a regulating position in which the regulating member protrudes from the handle portion and overlaps below a flange portion formed on the connecting frame, and a release position in which the regulating member does not overlap the flange portion.

6. The image forming apparatus of claim 5, wherein the regulating member is biased in a direction toward the regulating position by a second biasing member, and at least one of the regulating member and the flange portion has an inclined surface that is inclined in the direction of movement of the regulating member at a portion that comes into contact with the flange portion or the regulating member when the unit is attached to the main frame.

7. 6. The image forming apparatus according to claim 5, wherein the flange portion is formed with an operation hole for moving the regulating member from the regulating position to the release position against the biasing force of a second biasing member.

8. 2. The image forming apparatus according to claim 1, wherein the unit is an intermediate transfer unit including an endless intermediate transfer belt on which toner images to be transferred to a recording medium are sequentially stacked, and a plurality of suspension rollers that tension the intermediate transfer belt.

Images