Image forming device

Abstract

To improve convenience of operations to attach a detachable unit to a detachably attached position, while maintaining high positioning stability of the detachable unit to the detachably attached part.SOLUTION: In an image forming apparatus, a developing device that develops a latent image on a latent image carrier 2 arranged closer to a detachably attached part with developer carried on a developer carrier 41 is arranged in a detachable unit 4 that is detachably attached to the detachably attached part 1, and the image forming apparatus has a pressure member 33 that applies pressure to the detachable unit to generate an energizing force to energize the developer carrier toward the latent image carrier. The detachably attached part includes main reference parts 31a, 32a that are in contact with a main reference place 42 of the detachable unit for positioning, and a following reference part 34a that is in contact with a following reference place 43 of the detachable unit to receive the rotation around the main reference place in the detachable unit. The application of pressure performed by the pressure member generates a rotation moment toward the following reference part around the main reference place with respect to the detachable unit.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus. [Background technology]

[0002] Conventionally, there has been known an image forming apparatus in which a developing device is arranged in a detachable unit that is detachable from a detachable portion, and the developing device develops a latent image on a latent image carrier arranged on the detachable portion side by a developer carried on a developer carrier.

[0003] For example, Patent Document 1 discloses an image forming apparatus in which an image forming unit including a drum unit (detachable part) having a photosensitive member (latent image carrier) and a development unit (detachable unit) detachable from the drum unit is detachable from the image forming apparatus main body. A cylindrical protrusion (main reference part) and a U-shaped groove (sub-reference part) for positioning the development unit are formed in the drum unit, and a U-shaped groove (main reference point) and a protrusion (sub-reference point) corresponding to the drum unit are formed in the development unit. The U-shapes of both grooves are formed to face in the same direction, and the development unit is attached to the drum unit so that both protrusions fit in along the U-shapes of both grooves. As a result, the development unit is positioned in the image forming apparatus main body via the drum unit.

[0004] In addition, the drum unit is provided with a biasing member (pressure member) that presses the developing unit to generate a biasing force that biases the developing roller (developer carrier) of the developing unit toward the photosensitive member, on a holder that is rotatably attached to the drum unit. Before the developing unit is attached, the holder is rotated so that the biasing member retreats from the groove of the drum unit, and after the developing unit is attached, the holder is rotated and locked. As a result, the biasing member biases the protrusion of the developing unit toward the back of the groove of the drum unit, generating a biasing force that biases the developing roller toward the photosensitive member. Summary of the Invention [Problem to be solved by the invention]

[0005] However, in conventional image forming apparatuses, although the positioning of the detachable unit relative to the mounting portion is highly stable, the mounting operation of the detachable unit relative to the mounting portion is complicated, resulting in a problem of poor convenience. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, the present invention provides an image forming apparatus in which a developing device that develops a latent image on a latent image carrier arranged on the side of the attachment / detachment portion by a developer carried on a developer carrier is arranged in a removable unit that is removable from the attachment / detachment portion, the image forming apparatus having a pressing member that presses the attachment / detachment unit to generate a biasing force that biases the developer carrier toward the latent image carrier, and the attachment / detachment portion has a main reference that abuts against a main reference point of the attachment / detachment unit to position the attachment / detachment portion. Face and A secondary reference that abuts against a secondary reference point of the detachable unit to receive the rotation of the detachable unit about the primary reference point. Face and Equipped with The secondary reference surface is substantially parallel to the primary reference surface, The pressure of the pressure member is applied to the secondary reference point around the primary reference point with respect to the detachable unit. Face side It is characterized by generating a rotational moment toward the Effect of the Invention

[0007] According to the present invention, it is possible to improve the convenience of the operation of attaching the detachable unit to the detachable part while maintaining high positioning stability of the detachable unit to the detachable part. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to an embodiment. [Diagram 2] FIG. 2 is a schematic diagram showing a configuration of a process unit to which a development unit is detachably attached in the image forming apparatus. [Diagram 3] FIG. 2 is a schematic diagram showing the configuration of a development unit that is detachably mounted to the process unit. [Figure 4]FIG. 4 is an explanatory diagram showing a state in which the developing unit is being inserted into the process unit. [Diagram 5] FIG. 4 is an explanatory diagram showing a state in which the developing unit is inserted to the back of the process unit. [Figure 6] FIG. 11 is an explanatory diagram showing a state in which the developing unit is being rotated and attached to the process unit. [Figure 7] FIG. 4 is an explanatory diagram showing the developing unit attached to the process unit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment in which the present invention is applied to an electrophotographic monochrome image forming apparatus 100 as an image forming apparatus will be described. First, the basic configuration of the image forming apparatus will be described. FIG. 1 is a schematic diagram showing an example of an image forming apparatus 100 according to the present embodiment. 1, the image forming apparatus 100 is a monochrome image forming apparatus. A process unit 1 serving as an image forming unit is detachably attached to the apparatus main body (image forming apparatus main body).

[0010] The process unit 1 includes a photoconductor 2 as a latent image carrier that carries an image on its surface, a charging roller 3 as a charging means for charging the surface of the photoconductor 2, and a cleaning blade 5 as a cleaning means for cleaning the surface of the photoconductor 2. The process unit 1 also includes an LED head array 6 as an exposure means for exposing the surface of the photoconductor 2 to light, at a position facing the photoconductor 2. The process unit 1 also includes a developing unit 4 detachably mounted thereon, the developing unit 4 including a developing device as a developing means for converting the latent image on the photoconductor 2 into a visible image. In this embodiment, the process unit 1 is a removable part, and the developing unit 4 is a removable unit.

[0011] A toner cartridge 7 serving as a developer container, which is a toner container, is removably provided in the device main body of the image forming device 100 of this embodiment. The toner cartridge 7 has, in its container body 22, a developer container 8 serving as a toner container that contains toner, which is a developer to be replenished to the developing unit 4, and a developer recovery section 9 serving as a waste toner container that recovers toner removed by the cleaning blade 5 (waste toner).

[0012] The main body of the image forming apparatus 100 also includes a transfer device 10 that transfers an image onto paper as a recording material, a paper feeder 11 that supplies paper, a fixing device 12 that fixes the image transferred onto the paper, and a paper discharge device 13 that discharges the paper outside the apparatus.

[0013] The transfer device 10 includes a transfer roller 14 as a transfer member. The transfer roller 14 is in contact with the photoreceptor 2, and a transfer nip is formed at the contact portion between the two. The transfer roller 14 is also connected to a power source, and a predetermined direct current voltage (DC) and / or alternating current voltage (AC) is applied to the transfer roller 14.

[0014] The paper feed device 11 includes a paper feed cassette 15 that stores paper P, and a paper feed roller 16 that feeds the paper P stored in the paper feed cassette 15. In addition, downstream of the paper feed roller 16 in the paper transport direction, a pair of registration rollers 17 is provided as a timing roller that transports the paper to the transfer nip in time with the transport timing. The paper P includes cardboard, postcards, envelopes, plain paper, thin paper, coated paper (coated paper, art paper, etc.), tracing paper, etc. Also, it is possible to use overhead transparencies, overhead transparencies, cloth, etc. as recording materials other than paper.

[0015] The fixing device 12 includes a fixing roller 18 as a fixing member and a pressure roller 19 as a pressure member. The fixing roller 18 is adapted to be heated by a heat source such as a heater. The pressure roller 19 is pressed toward the fixing roller 18 and comes into contact with the fixing roller 18, forming a fixing nip at the contact point.

[0016] The paper discharge device 13 includes a pair of paper discharge rollers 20. Paper discharged to the outside of the device by the paper discharge rollers 20 is stacked on a paper discharge tray 21 formed by recessing the upper surface of the device body.

[0017] Next, the image forming operation of the image forming apparatus 100 according to this embodiment will be described. When an image forming operation is started, the photoconductor 2 is rotated and the surface of the photoconductor 2 is uniformly charged to a predetermined polarity by the charging roller 3. Then, based on image information from a reading device, a computer, or the like, an electrostatic latent image is formed on the charged surface of the photoconductor 2 by exposure to light from the LED head array 6. Toner is supplied to the electrostatic latent image thus formed on the photoconductor 2 by the developing roller 41, which serves as a developer carrier of the developing unit 4, and the electrostatic latent image is visualized as a toner image.

[0018] Furthermore, when the image forming operation is started, the paper feed roller 16 starts to rotate and feeds the paper P from the paper feed cassette 15. The conveyance of the fed paper P is temporarily stopped by the pair of registration rollers 17. Thereafter, the pair of registration rollers 17 starts to rotate at a predetermined timing and conveys the paper P to the transfer nip in time with the toner image on the photoconductor 2 reaching the transfer nip.

[0019] At this time, a transfer voltage of a polarity opposite to the toner charge polarity of the toner image on the photoreceptor 2 is applied to the transfer roller 14, which forms a transfer electric field in the transfer section. The toner image on the photoreceptor 2 is then transferred onto the paper P by this transfer electric field. Any residual toner on the photoreceptor 2 that has not been transferred to the paper P is removed by the cleaning blade 5 and collected in the developer collection section 9 in the toner cartridge 7.

[0020] The paper P onto which the toner image has been transferred is transported to the fixing device 12, where it is heated and pressed as it passes through the fixing nip between the fixing roller 18 and the pressure roller 19, thereby fixing the toner image on the paper P. The paper P is then discharged outside the device by the paper discharge rollers 20, and is stocked on the paper discharge tray 21.

[0021] Next, a configuration for attaching and detaching the developing unit 4 to and from the apparatus main body in this embodiment will be described. FIG. 2 is a schematic diagram showing the configuration of the process unit 1 to which the developing unit 4 is detachably attached. FIG. 3 is a schematic diagram showing the configuration of the developing unit 4 that is detachably mounted to the process unit 1. As shown in FIG.

[0022] The housing of the process unit 1 in this embodiment is provided with guide rails 31, 32 on both end faces (side faces) in the axial direction of the photoconductor 2, which guide the guided portion of the development unit 4 during attachment and detachment of the development unit 4. The guided portion of the development unit 4 in this embodiment is a main reference shaft 42 which is a main reference point for positioning the development unit 4 with respect to the process unit 1. Parts of the guide rails 31, 32 of the process unit 1 abut against the main reference shaft 42 on the side of the development unit 4 to form main reference surfaces 31a, 32a which serve as main reference portions for positioning the development unit 4 at a target position of the process unit 1.

[0023] Furthermore, the process unit 1 is provided with a secondary reference member 43 that forms a secondary reference surface 34a in order to stably position the developing unit 4. Furthermore, the process unit 1 is provided with a pressure member 33 that presses the developing unit 4 in order to generate a biasing force that biases the developing roller 41 of the developing unit 4 toward the photoconductor 2 of the process unit 1. The pressure member 33 generates a biasing force that biases the developing roller 41 toward the photoconductor 2 by pressing the pressure-receiving portion 44 of the developing unit 4 with the biasing force of the spring 33a by the pressure portion 33b.

[0024] A driven gear 41a that meshes with a drive gear 2a disposed on the rotation shaft of the photoconductor 2 of the process unit 1 is provided on the rotation shaft of the developing roller 41 provided in the developing unit 4. When the developing unit 4 is positioned with respect to the process unit 1, the drive gear 2a meshes with the driven gear 41a, and the developing roller 41 is rotated as the photoconductor 2 is rotated.

[0025] The main reference shaft 42 is provided coaxially with the rotation shaft of the developing roller 41 provided in the developing unit 4. The main reference shaft 42 is provided so as to protrude axially outward from the roller ends of the developing roller 41. The housing of the developing unit 4 is provided with a slave reference member 43 as a slave reference location that abuts against the slave reference surface 34a of the process unit 1. The housing of the developing unit 4 is provided with a pressurized portion 44 that abuts against the pressurizing portion 33b of the pressurizing member 33 of the process unit 1 and receives a pressurizing force. The housing of the developing unit 4 is also provided with a handle portion 45 that an operator can hold when attaching or detaching the developing unit 4 to or from the process unit 1.

[0026] Next, a method for mounting the developing unit 4 to the process unit 1 will be described with reference to FIGS. When mounting the developing unit 4 to the process unit 1, first, the worker grasps the handle portion 45 of the developing unit 4 and inserts the developing unit 4 into the process unit 1 from above the process unit 1 along the direction indicated by the arrow A in Fig. 4. At this time, the worker places the main reference shaft 42 formed on the side surface of the developing unit 4 (the end surface in the front-rear direction in Fig. 4) on the lower guide rail 31 and inserts the developing unit 4 into the process unit 1 by sliding the main reference shaft 42 along the lower guide rail 31.

[0027] 4, the lower guide rail 31 of the process unit 1 is inclined downward toward the insertion direction, so that the developing unit 4 can slide by its own weight without the operator pushing the developing unit 4 in the insertion direction. Since the main reference shaft 42 in this embodiment is a cylindrical member, no matter where on the circumferential surface of the main reference shaft 42 comes into contact with the lower guide rail 31, it is essentially a point contact, and since the contact area is small, the frictional force is small, allowing for a smooth sliding operation (insertion operation).

[0028] 5, when the developing unit 4 is fully inserted into the process unit 1, the developing roller 41 of the developing unit 4 comes into contact with the photoconductor 2 of the process unit 1 (used state). At this time, the driven gear 41a provided on the rotation shaft of the developing roller 41 of the developing unit 4 meshes with the driving gear 2a provided on the rotation shaft of the photoconductor 2 of the process unit 1.

[0029] Furthermore, when the developing unit 4 is inserted into the process unit 1 and the developing roller 41 comes into contact with the photoconductor 2, it cannot be inserted any further. As a result, the main reference shaft 42 of the developing unit 4 is inserted to a predetermined position in the guide rails 31, 32 of the process unit 1. At this predetermined position, the main reference shaft 42 is fitted between the part 31a of the lower guide rail 31 and the part 32a of the upper guide rail 32 with a slight gap between them. This completes the positioning of the main reference of the developing unit 4 with respect to the process unit 1. That is, the part 31a of the lower guide rail 31 and the part 32a of the upper guide rail 32 into which the main reference shaft 42 is fitted are the main reference surfaces in this embodiment.

[0030] In this manner, in this embodiment, parts of the guide rails 31, 32 form the main reference surfaces 31a, 32a. Therefore, the main reference shaft 42 that has slid on the lower guide rail 31 slides as it is to the position (predetermined position) of the main reference surfaces 31a, 32a, and reaches the main reference surfaces 31a, 32a, completing the positioning of the main reference of the developing unit 4 relative to the process unit 1.

[0031] If the primary reference surface is located at a different location from the guide rail, the primary reference shaft (which may be the same as or different from the guided part guided by the guide rail) must be brought into contact with (placed on) the primary reference surface, requiring the guided part to be moved away from (lifted up) the guide rail. This is because the primary reference cannot be positioned by contact between the primary reference surface and the primary reference shaft unless the guided part is moved away from the guide rail. In this case, a two-step process is required: sliding the guided part along the guide rail and then moving the guided part away from the guide rail, which reduces the convenience of the worker.

[0032] In contrast, according to this embodiment, the positioning of the main reference of the developing unit 4 relative to the process unit 1 can be completed simply by inserting the developing unit 4 into the process unit 1. This provides high convenience for the operator.

[0033] Once the positioning of the main reference has been completed in the above manner, the operator then rotates the developing unit 4 around the main reference shaft 42 in the direction indicated by the arrow B in Fig. 5, as shown in Fig. 5. At this time, a force is acting on the developing unit 4 to rotate in the direction indicated by the arrow B in Fig. 5 due to the rotational moment caused by its own weight, so the operator need only reduce the force supporting the handle portion 45 of the developing unit 4.

[0034] When the developing unit 4 rotates around the main reference shaft 42 in this manner, the pressure-receiving portion 44 of the developing unit 4 comes into contact with the upper surface 33b1 of the pressure-receiving portion 33b of the pressure-receiving member 33 of the process unit 1, as shown in Fig. 6. The upper surface 33b1 of the pressure-receiving portion 33b in this embodiment is an inclined surface as shown in Fig. 6, and part of the urging force of the spring 33a of the pressure-receiving member 33 acts as a force that resists the force of the weight of the developing unit 4 pressing down the pressure-receiving portion 33b. As a result, in this embodiment, the weight of the developing unit 4 alone cannot push aside the pressure-receiving portion 33b of the pressure-receiving member 33 against the urging force of the spring 33a, and the pressure-receiving portion 44 of the developing unit 4 remains on the upper surface 33b1 of the pressure-receiving portion 33b.

[0035] From this state, when the operator presses down the handle portion 45 of the developing unit 4 as shown by the arrow C in Fig. 6, the pressing portion 33b of the pressing member 33 can be pushed aside against the biasing force of the spring 33a. This allows the pressure-receiving portion 44 of the developing unit 4 to pass over the pressing portion 33b, and the developing unit 4 can be further rotated in the direction of the arrow B in Fig. 6.

[0036] When the developing unit 4 is further rotated in the direction of arrow B in Fig. 6 in this manner, the slave reference member 43 of the developing unit 4 comes into contact with the slave reference surface 34a of the process unit 1, as shown in Fig. 7. As a result, the rotation of the developing unit 4 around the master reference shaft 42 is received by the slave reference surface 34a, and the positioning of the slave reference of the developing unit 4 relative to the process unit 1 is completed. As a result, the position of the master reference shaft 42, which is the rotation shaft relative to the process unit 1, of the developing unit 4 is positioned by the master reference surfaces 31a, 32a, and the rotation position relative to the process unit 1 is positioned by the slave reference surface 34a. In this way, the developing unit 4 is positioned relative to the process unit 1.

[0037] At this time, the slave reference member 43 of the developing unit 4, which abuts against the slave reference surface 34a of the process unit 1, has a spherical or curved surface, so that the slave reference member 43 can essentially make point contact with the slave reference surface 34a, and can abut without any rattling.

[0038] Furthermore, when the slave reference member 43 of the developing unit 4 comes into contact with the slave reference surface 34a of the process unit 1, the pressure-receiving portion 44 of the developing unit 4 comes into contact with the lower surface 33b2 of the pressure-receiving portion 33b, as shown in Fig. 7. The lower surface 33b2 of the pressure-receiving portion 33b in this embodiment is an inclined surface as shown in Fig. 7, and part of the biasing force of the spring 33a of the pressure-receiving member 33 acts as a force to bias the pressure-receiving portion 44 of the developing unit 4 in the direction indicated by the arrow D in Fig. 7.

[0039] By the pressure member 33 pressing the developing unit 4 in this manner, the developing roller 41 of the developing unit 4 generates a biasing force that biases it toward the photoconductor 2. As a result, even if some external force (such as an impact) is applied and a force acts to move the developing roller 41 in a direction away from the photoconductor 2, the pressure force of the pressure member 33 (the biasing force of the spring 33a) can prevent the developing roller 41 from moving in the direction away from the photoconductor 2. In other words, the main reference shaft 42 of the developing unit 4 is prevented from moving in the pull-out direction (opposite to the insertion direction) along the guide rails 31, 32. Therefore, the positioning of the main reference of the developing unit 4 relative to the process unit 1 is stably maintained.

[0040] In particular, the secondary reference surface 34a in this embodiment is substantially parallel to the primary reference surfaces 31a and 32a. This unifies the direction in which the developing unit 4 can slide, and reduces the variation in the pressing force of the pressing member 33 that presses the developing roller 41 toward the photoconductor 2.

[0041] In addition, there is a risk that some external force (such as an impact) will act in a direction that moves the slave reference member 43 of the developing unit 4 away from the slave reference surface 34a of the process unit 1. In this case, there is a risk that the position of the developing unit 4 relative to the process unit 1 (the position of the slave reference) will be shifted.

[0042] In this embodiment, as shown in FIG. 7, the direction D of the pressure of the pressure member 33 is directed downward from the straight line E connecting the main reference shaft 42, the pressure member 33, and the contact point of the slave reference member 43, when viewed from the axial direction of the developing roller 41 (the axial direction of the master reference shaft 42). That is, the pressure of the pressure member 33 includes a force component that generates a rotational moment about the main reference shaft 42 toward the slave reference surface 34a of the process unit 1 with respect to the developing unit 4. Therefore, a part of the pressure of the pressure member 33 serves as a deterrent force that prevents the slave reference member 43 of the developing unit 4 from moving in a direction away from the slave reference surface 34a of the process unit 1. Therefore, the positioning of the slave reference of the developing unit 4 with respect to the process unit 1 is also stably maintained.

[0043] This makes it possible to omit a separate fixing member for preventing the development unit 4 from rotating in a direction in which the slave reference member 43 moves away from the slave reference surface 34a. If such a separate fixing member can be omitted, not only can the configuration be simplified, but the operator can also be saved from the task of operating a separate fixing member, further improving convenience.

[0044] The angle between the pressure direction D and the straight line E is preferably within a range of 10° to 30°. If this angle is less than 10°, the force pressing the slave reference member 43 against the slave reference surface 34a may be insufficient, and the positioning of the slave reference of the developing unit 4 relative to the process unit 1 may become unstable. If this angle is greater than 30°, the force required for the operator to pull up the handle portion 45 when removing the developing unit 4 from the process unit 1 may become large, which may reduce convenience.

[0045] In this embodiment, the pressure of the pressure member 33 is set so that the force component parallel to the secondary reference surface 34a is larger than the force component that generates the rotation moment around the above-mentioned primary reference shaft 42. Specifically, the inclination angle of the lower surface 33b2 of the pressure portion 33b of the pressure member 33 and the shape of the pressure-receiving portion 44 of the development unit 4 are determined so that such a pressure force is generated. By configuring so that such a pressure force is generated, the friction force between the secondary reference member 43 and the secondary reference surface 34a can be reduced, and a sufficient biasing force for biasing the development roller 41 of the development unit 4 toward the photoconductor 2 can be secured. As a result, the positioning of the primary reference of the development unit 4 relative to the process unit 1 can be more stabilized.

[0046] In this embodiment, as described above, the driven gear 41a provided on the rotation shaft of the developing roller 41 meshes with the drive gear 2a provided on the rotation shaft of the photoconductor 2, and the developing roller 41 receives drive from the photoconductor 2. At this time, the direction of the pressure angle of the driven gear 41a is in the direction in which the driven gear 41a moves away from the drive gear 2a. Therefore, in order to maintain proper meshing even when the developing roller 41 receives drive from the photoconductor 2, it is necessary to prevent the driven gear 41a from being displaced in the direction in which it moves away from the drive gear 2a.

[0047] The pressure of the pressure member 33 may be set so as to prevent the driven gear 41a from being displaced in a direction away from the driving gear 2a. In that case, however, there is a risk that the force for stably maintaining the positioning of the master and slave references of the developing unit 4 relative to the process unit 1 may be weakened.

[0048] When the developing roller 41 is driven by the photoconductor 2, if the driven gear 41a tries to displace in a direction away from the driving gear 2a, the developing unit 4 tries to displace in that direction in response to this displacement. However, in this embodiment, the direction of the pressure angle of the driven gear 41a is configured to be approximately perpendicular (for example, 90°±5°) to the main reference surface 31a. Therefore, even if the main reference shaft 42 of the developing unit 4 tries to displace in that direction, it is blocked by the main reference surface 31a of the lower guide rail 31 of the process unit 1, and the developing unit 4 cannot displace in that direction. Therefore, when the developing roller 41 is driven by the photoconductor 2, the driven gear 41a is prevented from displacing in a direction away from the driving gear 2a, and appropriate meshing between the driven gear 41a and the driving gear 2a is maintained.

[0049] In this embodiment, the detachable part is the process unit 1, but it may be the main body of the image forming apparatus. The developing unit 4, which is a detachable unit, may include devices and members other than the developing device.

[0050] The above description is merely an example, and each of the following aspects provides unique effects. [First aspect] In the first aspect, an image forming apparatus 100 is provided in which a developing device is disposed in a removable unit (e.g., developing unit 4) that is removable from a removable portion (e.g., process unit 1) and that develops a latent image on a latent image carrier (e.g., photoconductor 2) disposed on the removable portion side by a developer carried on a developer carrier (e.g., developing roller 41), the image forming apparatus 100 having a pressing member 33 that presses the removable unit to generate a pressing force that presses the developer carrier toward the latent image carrier, and the removable portion is provided with a pressing member 33 that presses the removable unit to generate a pressing force that presses the developer carrier toward the latent image carrier, The detachable unit is provided with a master reference portion (e.g., master reference surfaces 31a, 32a) which abuts against a master reference point (e.g., master reference axis 42) of the detachable unit to position it, and a slave reference portion (e.g., slave reference surface 34a) which abuts against a slave reference point (e.g., slave reference member 43) of the detachable unit to receive rotation of the detachable unit about the master reference point, and the application of pressure by the pressure member generates a rotational moment on the detachable unit about the master reference point toward the slave reference portion. In conventional image forming devices, the pressure of the pressure member that presses the removable unit to generate a biasing force that biases the developer carrier toward the latent image carrier also acts as a deterrent to prevent the removable unit from moving in a direction away from the removable part. Therefore, the pressure of the pressure member makes it difficult for the removable unit to move in a direction away from the removable part and become displaced, and the positioning of the removable unit relative to the removable part is highly stable. However, in conventional image forming devices, the main and secondary references for positioning the removable unit relative to the removable part are both configured to insert a protrusion into a U-shaped groove. Therefore, when attaching the removable unit to the removable part, the worker is forced to insert the protrusion into the groove of the main reference and also into the groove of the secondary reference. This work involves the cumbersome task of simultaneously inserting the protrusion into both grooves, which is inconvenient for the worker. In contrast, in this embodiment, when the detachable unit is attached to the attached / detached part, first, the main reference point is brought into contact with the main reference part to position the main reference of the detachable unit relative to the attached / detached part. Then, after this positioning of the main reference is completed, the detachable unit is rotated around the main reference point to bring the secondary reference point of the detachable unit into contact with the secondary reference part of the attached / detached part to position the secondary reference. In this way, if the work of positioning the secondary reference is performed after positioning the main reference, there is no need to position the secondary reference during the work of positioning the main reference, and there is no need to position the main reference during the work of positioning the secondary reference. This makes the work extremely simple and convenient for the worker. Moreover, in this embodiment, the pressure of the pressure member that presses the removable unit to generate a biasing force that biases the developer carrier toward the latent image carrier generates a rotational moment around the master reference point toward the slave reference portion with respect to the removable unit. Therefore, part of the pressure of the pressure member acts as a deterrent force that prevents the slave reference point of the removable unit from moving in a direction away from the slave reference portion of the removable portion. Therefore, the positioning of the removable unit with respect to the removable portion is highly stable.

[0051] [Second aspect] The second aspect is characterized in that, in the first aspect, the developer carrier is provided with a driven gear 41a on the rotation shaft of the developer carrier, which meshes with a drive gear 2a arranged on the rotation shaft of the latent image carrier. According to this, even if the pressure angle of the driven gear is oriented in a direction in which the driven gear moves away from the drive gear, the driven gear can be prevented from moving away from the drive gear due to the pressure force of the pressure member, thereby maintaining proper meshing between the driven gear and the drive gear.

[0052] [Third aspect] A third aspect is the second aspect, characterized in that the direction of the pressure angle of the driven gear is approximately perpendicular to the plane of the main reference portion. According to this, the movement of the driven gear away from the driving gear can be received by the surface of the master reference part, and therefore proper meshing between the driven gear and the driving gear is maintained without weakening the action of the pressure of the pressure member that acts as a deterrent to prevent the secondary reference part of the detachable unit from moving in a direction away from the secondary reference part of the detachable part.

[0053] [Fourth aspect] The fourth aspect is characterized in that, in any one of the first to third aspects, the detachable part is provided with guide rails 31, 32 that guide the main reference point during attachment and detachment of the detachable unit, and a part of the guide rails constitutes the main reference point. According to this, the positioning of the main reference of the detachable unit relative to the receiving part can be completed simply by moving the detachable unit along the guide rail, which makes it more convenient for the worker.

[0054] [Fifth aspect] A fifth aspect is characterized in that in any one of the first to fourth aspects, a surface of the secondary reference portion is approximately parallel to a primary reference surface that constitutes a surface of the primary reference portion. According to this, the movable direction of the detachable unit is unified, and the variation in the urging force with which the developer carrier is urged toward the latent image carrier by the pressure of the pressure member is reduced.

[0055] [Sixth aspect] A sixth aspect is characterized in that, in any one of the first to fifth aspects, the pressure applied by the pressure member has a force component parallel to the surface of the secondary reference part that is greater than the force component that generates the rotational moment. This makes it possible to reduce the frictional force between the secondary reference point and the secondary reference portion, thereby ensuring a sufficient urging force for urging the developer carrier of the removable unit toward the latent image carrier.

[0056] [Seventh aspect] The seventh aspect is characterized in that in any of the first to sixth aspects, the pressure direction D of the pressure member is in the range of 10° to 30° with respect to a line E connecting the rotation axis of the latent image carrier and the rotation axis of the developer carrier when viewed from the rotation axis direction of the latent image carrier. If it is less than 10°, the force pressing the slave reference point against the slave reference part may be insufficient, and the positioning of the slave reference of the detachable unit relative to the detachable part may become unstable. Also, if it is more than 30°, the force required by the worker to detach the detachable unit from the detachable part may become large, which may reduce convenience.

[0057] [Eighth aspect] An eighth aspect is characterized in that in any one of the first to seventh aspects, the secondary reference portion is a curved surface. This enables the secondary reference point to be in substantial point contact with the secondary reference portion, and enables the contact to be effected without any wobble, thereby enhancing the stability of the positioning of the detachable unit relative to the detachable portion. [Explanation of symbols]

[0058] 1: Process unit 2: Photoreceptor 2a: Drive gear 3: Charging roller 4: Development unit 5: Cleaning blade 6: LED head array 7: Toner cartridge 10: Transfer device 11: Paper feeder 12: Fixing device 13: Paper ejection device 14: Transfer roller 15: Paper feed cassette 16: Paper feed roller 17: Registration roller pair 20: Paper ejection roller 31: Lower guide rail 31a, 32a: Main reference plane 32: Upper guide rail 33: Pressure member 33a: Spring 33b: Pressurizing section 33b1:Top surface 33b2:Bottom surface 34: Sub-reference member 34a: Secondary reference surface 41: Developing roller 41a: Driven gear 42:Main reference axis 43: Sub-reference member 44: Pressurized part 45: Handle 100: Image forming apparatus [Prior art documents] [Patent documents]

[0059] [Patent Document 1] JP 2010-170010 A

Claims

1. An image forming apparatus in which a developing device that develops a latent image on a latent image carrier arranged on the side of the mounting / detaching section by a developer carried on a developer carrier is arranged in a detachable unit that is detachable from the mounting / detaching section, a pressing member that presses the removable unit to generate a pressing force that presses the developer carrier toward the latent image carrier; the detachable portion includes a main reference surface that abuts against a main reference point of the detachable unit to position the detachable unit, and a secondary reference surface that abuts against a secondary reference point of the detachable unit to receive rotation of the detachable unit about the main reference point, The secondary reference surface is substantially parallel to the primary reference surface, The image forming apparatus according to claim 1, wherein the pressure applied by the pressure member generates a rotation moment around the master reference point toward the slave reference surface with respect to the removable unit.

2. 2. The image forming apparatus according to claim 1, The image forming apparatus according to claim 1, wherein the developer carrier has a rotation shaft on which a driven gear meshes with a drive gear arranged on the rotation shaft of the latent image carrier.

3. 3. The image forming apparatus according to claim 2, 4. An image forming apparatus according to claim 1, wherein the direction of the pressure angle of said driven gear is substantially perpendicular to said main reference plane.

4. 4. The image forming apparatus according to claim 1, the detachable portion includes a guide rail that guides the main reference point during attachment and detachment of the detachable unit, An image forming apparatus, wherein a part of the guide rail constitutes the main reference surface.

5. In the image forming apparatus according to any one of claims 1 to 4, The image forming apparatus according to claim 1, wherein the pressure applied by the pressure member has a force component parallel to the reference surface that is greater than a force component that generates the rotational moment.

6. 6. The image forming apparatus according to claim 1, an image forming apparatus characterized in that the direction of pressure applied by the pressure member, when viewed from the direction of the rotation axis of the latent image carrier, is within a range of 10° to 30° with respect to a line connecting the rotation axis of the latent image carrier and the rotation axis of the developer carrier.

7. 7. The image forming apparatus according to claim 1, The image forming apparatus according to claim 1, wherein the secondary reference portion is a curved surface.

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