Image forming device

Abstract

To provide an image forming apparatus that has improved the accuracy of positioning of a detachable unit to an apparatus body.SOLUTION: An image forming apparatus forms an image on a sheet, and comprises an apparatus body, and a detachable unit that is attached to the apparatus body in an attachment direction and detachably supported by the apparatus body. The detachable unit has a first part to be positioned and a second part to be positioned. The apparatus body has one frame member including both a first positioning part that is engaged with the first part to be positioned to determine the position of the detachable unit in the attachment direction, and a second positioning part that is engaged with the second part to be positioned to determine the position of the detachable unit in a first direction intersecting with the attachment direction. The second positioning part is arranged at a position different from the first positioning part in a second direction intersecting with the attachment direction and the first direction.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus that forms an image on a sheet. [Background technology]

[0002] Conventionally, an image forming apparatus has been proposed that has a process cartridge that is detachably supported in the apparatus main body, and that allows the process cartridge to be replaced (see Patent Document 1). This apparatus main body has a pair of side plates on the left and right, and two rail-like grooves are formed in the side plates. The process cartridge is positioned by engaging the first and second positioning portions of the process cartridge with the ends of these grooves. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-112731 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the side plate described in Patent Document 1 has two large rail-shaped grooves formed on the same plane, which may reduce its rigidity. If the rigidity of the side plate that supports the process cartridge is reduced, there is a risk that the positioning accuracy of the process cartridge will decrease.

[0005] Therefore, the present invention , Yu An object of the present invention is to provide an image forming apparatus in which the accuracy of positioning a knit relative to the apparatus body is improved. [Means for solving the problem]

[0006] The present invention provides an image forming apparatus for forming an image on a sheet, a unit including a photosensitive drum rotatable about a rotation axis extending in a rotation axis direction intersecting with the direction of gravity, a developing roller that supplies toner to the photosensitive drum, and a first protrusion and a second protrusion that protrude from an end face of the unit in the rotation axis direction, and the unit is detachably attached; The device body and ,of Preparation, the first protrusion has a first abutment portion including a first abutment surface, the second protrusion has a second abutment portion including a second abutment surface, a tip of the second protrusion is provided more inward of the unit than the tip of the first protrusion in the rotation axis direction, and the unit is configured to be attached to the device body from a first position where a part of the unit is located outside the device body along an attachment direction that intersects both the rotation axis direction and the gravity direction, to a second position where the unit is located inside the device body and is positioned with respect to the device body in the attachment direction, The device body is KiyuThe end of the knit surface to Opposite side plates and the side plate portion of the device body has a first abutment portion and a second abutment portion arranged in the mounting direction, the first abutment portion has a first abutment surface that abuts against the first abutment surface of the first abutment portion of the unit when the unit is located at the second position, the second abutment portion has a second abutment surface that abuts against the second abutment surface of the second abutment portion of the unit when the unit is located at the second position, the second abutment surface is arranged downstream of the first abutment surface in the mounting direction and more inward of the device body than the first abutment surface in the rotational axis direction, and the second abutment surface is arranged downstream of the first abutment surface in the mounting direction and more inward of the unit than the first abutment surface in the rotational axis direction. Characterized by 。 [Effects of the Invention]

[0007] According to the present invention , Yu This improves the positioning accuracy of the knit with respect to the device body. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic view showing an entire image forming apparatus according to a first embodiment. [Figure 2] FIG. 1 is a cross-sectional view showing a configuration of an image forming apparatus. [Figure 3] 1A is a perspective view showing an image forming apparatus with a rear cover closed, and FIG. 1B is a perspective view showing an image forming apparatus with a rear cover open. [Figure 4] FIG. 2 is a perspective view showing the image forming apparatus before a process unit is attached. [Figure 5] 1A is a rear view and an enlarged view showing the positioning configuration of the process unit by the left plate frame, and FIG. 1B is a rear view and an enlarged view showing the positioning configuration of the process unit by the right plate frame. [Figure 6] FIG. 1A is a perspective view showing an image forming apparatus with a process unit attached, FIG. 1B is an enlarged view showing a left positioning unit and a left rotation restricting unit, and FIG. 1C is an enlarged view showing a left positioning unit and a left rotation restricting unit according to a modified example of the first embodiment. [Figure 7] 1A is a cross-sectional view parallel to the XY plane showing the positioning configuration of the process unit by the left plate frame, and FIG. 1B is a cross-sectional view parallel to the XY plane showing the positioning configuration of the process unit by the right plate frame. [Figure 8] FIG. 10 is a left side view showing the positioning configuration of the process unit by the left plate frame. [Figure 9] FIG. 10 is a perspective view showing an image forming apparatus according to a second embodiment. [Figure 10]1A is a rear view and an enlarged view showing the positioning configuration of the process unit by the left plate frame, and FIG. 1B is a rear view and an enlarged view showing the positioning configuration of the process unit by the right plate frame. [Figure 11] FIG. 2 is a perspective view showing the image forming apparatus with a process unit attached thereto. [Figure 12] FIG. 10 is a perspective view showing an image forming apparatus according to a third embodiment. [Figure 13] FIG. 10 is a left side view showing the positioning configuration of the process unit by the left plate frame. DETAILED DESCRIPTION OF THE INVENTION

[0009] The following describes in detail exemplary embodiments of the present invention with reference to the drawings. However, the dimensions, materials, shapes, and relative positions of the components described in the embodiments may be changed as appropriate depending on the configuration of the device to which the invention is applied and various conditions. In other words, the scope of the present invention is not limited to the following embodiments.

[0010] First Embodiment Fig. 1 is a perspective view showing an image forming apparatus 1 according to a first embodiment. Fig. 2 is a cross-sectional view showing the configuration of the image forming apparatus 1. The image forming apparatus 1 is a monochrome printer that forms an image on a recording material based on image information input from an external device. The recording material includes various sheet materials of different materials, such as paper such as plain paper and cardboard, plastic film such as sheets for overhead projectors, sheets of special shapes such as envelopes and index paper, and cloth.

[0011] In the following description, the height direction of the image forming apparatus 1 (the direction opposite to the vertical direction) when the image forming apparatus 1 is installed on a horizontal surface is referred to as the Z direction. The direction that intersects with the Z direction and is parallel to the direction of the rotation axis of the photosensitive drum 11 (main scanning direction) described later is referred to as the X direction. The direction that intersects with the X and Z directions is referred to as the Y direction. The X, Y, and Z directions preferably intersect perpendicularly with each other. For convenience, the positive side in the X direction is referred to as the right side and the negative side is referred to as the left side; the positive side in the Y direction is referred to as the front side or front side and the negative side is referred to as the rear side or back side; and the positive side in the Z direction is referred to as the upper side and the negative side is referred to as the lower side.

[0012] [Overall configuration] As shown in Figures 1 and 2, the image forming apparatus 1 has an image forming section 40 that forms a toner image on a recording material, a feeding section 30 that feeds the recording material P, a fixing unit 9 that fixes the toner image formed by the image forming section 40 to the recording material, and a pair of discharge rollers 10.

[0013] The image forming section 40 has a scanner unit 50, an electrophotographic process unit 20, and a transfer roller 7 that transfers a toner image formed on a photosensitive drum 11 of the process unit 20 onto a recording material P as a sheet. The process unit 20 has the photosensitive drum 11, a cleaning unit 13 arranged around the photosensitive drum 11, a charging roller 17, a developing roller 12, and a storage section 18 that stores toner. The process unit 20 may be fastened to the device body 2 of the image forming apparatus 1 with screws, and may also be removable by a service technician.

[0014] The photosensitive drum 11 serving as an image carrier is a cylindrically shaped photosensitive member. The photosensitive drum 11 of this embodiment has a photosensitive layer formed of a negatively chargeable organic photosensitive material on a drum-shaped substrate made of aluminum. The photosensitive drum 11 serving as an image carrier is driven to rotate in a predetermined direction (direction R in the figure) at a predetermined process speed by a motor.

[0015] The charging roller 17 contacts the photosensitive drum 11 with a predetermined pressure to form a charging portion. A desired charging voltage is applied from a charging high-voltage power supply, thereby uniformly charging the surface of the photosensitive drum 11 to a predetermined potential. In this embodiment, the photosensitive drum 11 is negatively charged by the charging roller 17.

[0016] The scanner unit 50 uses a polygon mirror to irradiate the photosensitive drum 11 with laser light corresponding to image information input from an external device, thereby scanning and exposing the surface of the photosensitive drum 11. This exposure forms an electrostatic latent image corresponding to the image information on the surface of the photosensitive drum 11. Note that the scanner unit 50 is not limited to a laser scanner device, and may, for example, be an LED exposure device having an LED array in which a plurality of LEDs are arranged along the longitudinal direction of the photosensitive drum 11.

[0017] The developing roller 12 is rotatably supported by a storage section 18 serving as a toner storage section. The developing roller 12 is disposed to face the photosensitive drum 11. The storage section 18 may be provided with a supply roller that applies the toner stored in the storage section 18 as the developer onto the surface of the developing roller 12.

[0018] The process unit 20 serving as a detachable unit in this embodiment employs a contact development system. That is, a toner layer carried on the developing roller 12 comes into contact with the photosensitive drum 11 in a development section (development area) where the photosensitive drum 11 and the developing roller 12 face each other. A development voltage is applied to the developing roller 12 by a high-voltage development power supply. Under the development voltage, the toner carried on the developing roller 12 is transferred from the developing roller 12 to the drum surface in accordance with the potential distribution on the surface of the photosensitive drum 11, thereby developing the electrostatic latent image into a toner image.

[0019] The toner of this embodiment does not contain a magnetic component, and is a so-called non-magnetic one-component developer in which the toner is carried on the developing roller 12 mainly by intermolecular forces and electrostatic forces (image forces). However, a one-component developer containing a magnetic component may also be used. In addition to toner particles, a one-component developer may also contain additives (e.g., wax or silica particles) for adjusting the fluidity and charging performance of the toner. A two-component developer composed of non-magnetic toner and a magnetic carrier may also be used as the developer. When a magnetic developer is used, a cylindrical developing sleeve with a magnet disposed inside is used as the developer carrier, for example.

[0020] The fixing unit 9 is a thermal fixing type that fixes the image by heating and melting the toner on the recording material and applying pressure. The fixing unit 9 is equipped with a heating roller 9a incorporating a fixing heater 9c, and a pressure roller 9b that presses against the heating roller 9a.

[0021] The feeding section 30 has a cassette 4 on which the recording material P is loaded, a pickup roller 3, a feeding roller 5a, and a separation roller 5b. A front cover 70 is provided on a portion of the front end surface of the image forming apparatus 1, and the front cover 70 covers a circuit board 100. The apparatus body 2 of the image forming apparatus 1 has a housing 72. The housing 72 has the front cover 70, a discharge tray 14, a rear cover 75 (see FIGS. 3(a) and 3(b)), and an exterior cover 71 that forms the exterior of the image forming apparatus 1 other than the front cover 70, the discharge tray 14, and the rear cover 75. The housing 72 has a discharge opening 15 through which sheets pass to be discharged onto the discharge tray 14.

[0022] The process unit 20 is also provided with a supply port 200 (see FIG. 4) as a receiving port for receiving toner supplied from the outside. The supply port 200 communicates with the storage section 18, and is exposed by opening the discharge tray 14 upward while the process unit 20 is attached to the apparatus main body 2. The user can then attach a replenishment toner container to the exposed supply port 200, thereby supplying toner to the storage section 18 through the supply port 200. In this way, the process unit 20 of the present embodiment is configured to be able to replenish toner to the storage section 18 while attached to the apparatus main body 2.

[0023] As shown in FIG. 2, the image forming apparatus 1 has a circuit board 100. The circuit board 100 is composed of a wiring board 101 made of an insulator and electronic components 111 and 121 soldered to the wiring board 101. Conductor wiring is provided on and inside the wiring board 101, so that the electronic components 111 and 121 are electrically connected. The circuit board 100 has the function of converting AC current supplied from outside the image forming apparatus 1 into DC current, and converting the input voltage to obtain a predetermined voltage value required for the image formation process.

[0024] The circuit board 100 is oriented such that the surface of the wiring board 101 on which the electronic components 111 and 121 are mounted intersects with the ejection direction. Furthermore, the wiring board 101 is provided between the front cover 70 and the scanner unit 50 in the ejection direction. The electronic components 111 and 121 are provided on the surface of the wiring board 101 facing the scanner unit 50.

[0025] Next, an image forming operation of the image forming apparatus 1 will be described. When an image formation command is input to the image forming apparatus 1, the image forming process is started by the image forming section 40 based on image information input from an external computer connected to the image forming apparatus 1. The scanner unit 50 irradiates the photosensitive drum 11 with laser light based on the input image information. At this time, the photosensitive drum 11 is pre-charged by the charging roller 17, and an electrostatic latent image is formed on the photosensitive drum 11 by the irradiation of the laser light. Thereafter, the electrostatic latent image is developed by the developing roller 12, and a toner image is formed on the photosensitive drum 11.

[0026] In parallel with the image forming process described above, a pickup roller 3 of a feeding unit 30 feeds out recording material P supported by a cassette 4. The recording material P is separated into individual sheets by a feeding roller 5a and a separation roller 5b, and conveyed to a conveying roller pair 5c. The recording material P is then conveyed by the conveying roller pair 5c, which serves as a conveying unit, toward a transfer nip N1 formed by a transfer roller 7 and a photosensitive drum 11.

[0027] A transfer voltage is applied to the transfer roller 7 from a transfer high-voltage power supply, and the toner image carried on the photosensitive drum 11 is transferred onto the recording material P being conveyed by the conveying roller pair 5c. The recording material P with the transferred toner image is conveyed to the fixing unit 9, and the toner image is heated and pressurized as it passes through a nip between the heating roller 9a and pressure roller 9b of the fixing unit 9. This melts the toner particles and then solidifies them, thereby fixing the toner image to the recording material P. After passing through the fixing unit 9, the recording material P is discharged from a discharge port 15 by a discharge roller pair 10 to the outside of the image forming apparatus 1 (outside the machine) and is stacked on a discharge tray 14.

[0028] When forming images on both sides of the recording material P, the pair of discharge rollers 10 switches back the recording material P with the image formed on its first side, thereby guiding the recording material P to the double-sided conveying path 16. The recording material P guided to the double-sided conveying path 16 is conveyed again toward the transfer roller 7 by the pair of double-sided conveying rollers 5d. After an image is formed on the second side of the recording material P by the transfer roller 7, the recording material P is discharged outside the apparatus by the pair of discharge rollers 10. After the toner image is transferred onto the recording material P, any toner remaining on the photosensitive drum 11 is cleaned by the cleaning unit 13.

[0029] As shown in Figures 3(a) and 3(b), a rear cover 75 that is supported so as to be openable and closable is provided on the rear of the image forming apparatus 1. The rear cover 75, which serves as an openable / closable member, covers the process unit 20 when closed and exposes the process unit 20 when opened. With the rear cover 75 open, the process unit 20 can be attached to the apparatus main body 2 in an attachment direction AD shown in Figure 4, and can be removed in a removal direction opposite to the attachment direction AD. The attachment direction AD is along the Y direction.

[0030] Furthermore, by opening the rear cover 75, the duplex conveying path 16 (see FIG. 2) is opened. That is, the rear cover 75 is movable between a closed position that covers the duplex conveying path 16 and an open position that exposes the duplex conveying path 16 to the outside. This makes it possible to clear a jam that occurs in the duplex conveying path 16. Furthermore, by opening a transfer unit (not shown) when the duplex conveying path 16 is in the open position, the conveying path 19 (see FIG. 2) through which the sheet conveyed by the conveying roller pair 5c passes is opened.

[0031] [Process unit positioning configuration] Next, the positioning configuration of the process unit 20 will be described with reference to Figures 4 to 8. Figure 4 is a perspective view showing the image forming apparatus 1 before the process unit 20 is installed. Figure 5(a) is a rear view and an enlarged view showing the positioning configuration of the process unit 20 by the left side plate frame 73, and Figure 5(b) is a rear view and an enlarged view showing the positioning configuration of the process unit 20 by the right side plate frame 74.

[0032] 4, the process unit 20 has a left side surface 30L and a right side surface 30R as end surfaces in a longitudinal direction LD parallel to the X direction. A left positioning boss 21L as a first positioned portion and a left rotation restriction boss 22L as a second positioned portion are provided on the left side surface 30L, and a right positioning boss 21R and a right rotation restriction boss 22R are provided on the right side surface 30R (see FIG. 7(b)). The left positioning boss 21L and the right positioning boss 21R are disposed upstream of the left rotation restriction boss 22L and the right rotation restriction boss 22R, respectively, in the installation direction AD of the process unit 20.

[0033] The device body 2 of the image forming device 1 has a left side plate frame 73 and a right side plate frame 74 made of sheet metal members, and these left side plate frame 73 and right side plate frame 74 face each other with a gap in the longitudinal direction LD, which is the second direction.

[0034] As shown in FIGS. 4 and 5(a), the left side plate frame 73 serving as a frame member has a first left surface 81Lf and a second left surface 82Lf extending in the mounting direction AD (Y direction) and the Z direction. The second left surface 82Lf is disposed inward of the device body 2 by a distance X1 from the first left surface 81Lf in the longitudinal direction LD by drawing the first left surface 81Lf. In other words, the first left surface 81Lf and the second left surface 82Lf are not coplanar. In this embodiment, the second left surface 82Lf serving as the second surface is configured as a surface parallel to the mounting direction AD (Y direction) and the Z direction, but is not limited thereto. For example, the second left surface 82Lf may be a curved surface along the mounting direction AD (Y direction) and the Z direction.

[0035] The first left surface 81Lf is formed with a left positioning portion 81L with which the left positioning boss 21L can engage, and the left positioning portion 81L as a first positioning portion is a notch that is open on the upstream side in the installation direction AD. The second left surface 82Lf is formed with a left rotation restricting portion 82L with which the left rotation restricting boss 22L can engage, and the left rotation restricting portion 82L as a second positioning portion is a U-shaped notch that is open on the upstream side in the installation direction AD. Note that, because the second left surface 82Lf is formed by drawing, a slope that guides the left positioning boss 21L toward the left positioning portion 81L may be formed.

[0036] Since the first left surface 81Lf and the second left surface 82Lf are spaced apart by the distance X1 in the longitudinal direction LD, the left rotation restricting portion 82L is also spaced apart by the distance X1 in the longitudinal direction LD from the left positioning portion 81L. In other words, the left rotation restricting portion 82L is located at a different position from the left positioning portion 81L in the longitudinal direction LD.

[0037] Similarly, as shown in FIGS. 4 and 5(b), the right side plate frame 74 has a right first surface 81Rf and a right second surface 82Rf extending along the installation direction AD (Y direction) and the Z direction. The right second surface 82Rf is disposed inward of the device body 2 from the right first surface 81Rf in the longitudinal direction LD by a distance X2 by drawing the right first surface 81Rf. In other words, the right first surface 81Rf and the right second surface 82Rf are not coplanar. In this embodiment, the right first surface 81Rf and the right second surface 82Rf are configured as surfaces parallel to the installation direction AD (Y direction) and the Z direction, but are not limited thereto. For example, the right second surface 82Rf may be a curved surface along the installation direction AD (Y direction) and the Z direction.

[0038] The right first surface 81Rf is formed with a right positioning portion 81R with which the right positioning boss 21R can engage, and the right positioning portion 81R is a notch that is open on the upstream side in the installation direction AD. The right second surface 82Rf is formed with a right rotation restricting portion 82R with which the right rotation restricting boss 22R can engage, and the right rotation restricting portion 82R is a U-shaped notch that is open on the upstream side in the installation direction AD. Note that, because the right second surface 82Rf is formed by drawing, a slope that guides the right positioning boss 21R toward the right positioning portion 81R may be formed.

[0039] Since the first right surface 81Rf and the second right surface 82Rf are spaced apart by the distance X2 in the longitudinal direction LD, the right rotation restricting portion 82R is also spaced apart by the distance X2 in the longitudinal direction LD from the right positioning portion 81R. In other words, the right rotation restricting portion 82R is located at a different position from the right positioning portion 81R in the longitudinal direction LD.

[0040] FIG. 6(a) is a perspective view showing the image forming apparatus 1 with the process unit 20 attached, and FIG. 6(b) is an enlarged view showing the left positioning portion 81L and the left rotation restricting portion 82L. As shown in FIGS. 5(a) to 6(b), when the process unit 20 is attached to the apparatus body 2, the process unit 20 is biased from the rear side toward the front side by a biasing mechanism (not shown). When the process unit 20 is attached to the apparatus body 2, the left positioning boss 21L and the left rotation restricting boss 22L of the process unit 20 engage with the left positioning portion 81L and the left rotation restricting portion 82L of the left side plate frame 73, respectively. Similarly, when the process unit 20 is attached to the apparatus body 2, the right positioning boss 21R and the right rotation restricting boss 22R of the process unit 20 engage with the right positioning portion 81R and the right rotation restricting portion 82R of the right side plate frame 74, respectively.

[0041] The process unit 20 is positioned in the installation direction AD by the left positioning boss 21L and the right positioning boss 21R engaging with the left positioning portion 81L and the right positioning portion 81R, respectively. Furthermore, the left rotation restriction boss 22L and the right rotation restriction boss 22R engaging with the left rotation restriction portion 82L and the right rotation restriction portion 82R, respectively, restricts rotational movement of the process unit 20 about the left positioning boss 21L and the right positioning boss 21R. In other words, the process unit 20 is positioned in the Z direction, which is the first direction.

[0042] 6(b), the left positioning portion 81L has protrusions 51, 52, and 53 against which the left positioning boss 21L abuts. When the process unit 20 is mounted to the apparatus main body 2, the left positioning boss 21L abuts against the protrusions 51 and 52 in the mounting direction AD and is positioned therein. At this time, the left positioning boss 21L abuts against the protrusions 51, 52, and 53 in the Z direction, and is therefore positioned therein. In other words, the left positioning portion 81L, together with the left rotation restricting portion 82L, positions the process unit 20 in the Z direction.

[0043] Furthermore, when the process unit 20 is attached to the apparatus main body 2, i.e., when the left positioning boss 21L is in contact with the protrusions 51, 52, and 53, the left rotation restricting boss 22L has a gap G in the attachment direction AD relative to the left rotation restricting portion 82L. In other words, when the process unit 20 is positioned in the attachment direction AD by the left positioning portion 81L, the left rotation restricting portion 82L is configured not to position the process unit 20 in the attachment direction AD. This ensures that the process unit 20 is reliably positioned in the attachment direction AD by the left positioning portion 81L, improving the positioning accuracy of the process unit 20.

[0044] The right positioning portion 81R and the right rotation restricting portion 82R have the same configuration as the left positioning portion 81L and the left rotation restricting portion 82L, and therefore a description thereof will be omitted.

[0045] Fig. 6(c) is an enlarged view showing a left positioning portion 281L and a left rotation restricting portion 282L according to a modification of the first embodiment. In the present embodiment shown in Fig. 6(b), the left positioning portion 81L is disposed upstream of the left rotation restricting portion 82L in the mounting direction AD, but this is not limiting. For example, as shown in Fig. 6(c), the left positioning portion 281L as the first positioning portion may be disposed downstream of the left rotation restricting portion 282L as the second positioning portion in the mounting direction AD.

[0046] The left positioning portion 281L has surfaces 251, 252, and 253, and the surfaces 251 and 253 face each other in the Z direction. When the process unit 20 is attached to the apparatus main body 2, the left positioning boss 221L, which serves as the first positioned portion, abuts against the surface 252 of the left positioning portion 281L and is positioned in the attachment direction AD. At this time, the left positioning boss 221L also abuts against the surfaces 251 and 253 in the Z direction, and is therefore also positioned in the Z direction.

[0047] The left rotation restricting portion 282L has protrusions 261, 262. When the process unit 20 is positioned in the installation direction AD by the left positioning portion 281L, the left rotation restricting boss 222L, which serves as the second positioned portion, is positioned in the Z direction by abutting against the protrusions 261, 262. At this time, the left rotation restricting boss 222L has a gap G2 in the installation direction AD relative to the left rotation restricting portion 282L. In other words, when the process unit 20 is positioned in the installation direction AD by the left positioning portion 281L, the left rotation restricting portion 282L is configured not to position the process unit 20 in the installation direction AD. This ensures that the process unit 20 is reliably positioned in the installation direction AD by the left positioning portion 281L, improving the positioning accuracy of the process unit 20.

[0048] Figure 7(a) is a cross-sectional view parallel to the XY plane showing the positioning configuration of the process unit 20 by the left side plate frame 73, and Figure 7(b) is a cross-sectional view parallel to the XY plane showing the positioning configuration of the process unit 20 by the right side plate frame 74.

[0049] As shown in FIG. 7A, the left second surface 82Lf on which the left rotation restricting portion 82L is formed is disposed closer to the inside of the device body 2 in the longitudinal direction LD than the left first surface 81Lf on which the left positioning portion 81L is formed. The left rotation restricting boss 22L is also disposed closer to the inside of the device body 2 in the longitudinal direction LD than the left positioning boss 21L. This allows the cutout shape forming the left rotation restricting portion 82L, formed on the left second surface 82Lf, to have a relatively small area. Furthermore, because the left positioning portion 81L is disposed upstream of the left rotation restricting portion 82L in the mounting direction AD, the cutout shape forming the left positioning portion 81L, formed on the left first surface 81Lf, also requires a relatively small area. By reducing the area of ​​the cutout formed in the left side plate frame 73 in this way, the rigidity of the left side plate frame 73 can be maintained.

[0050] Similarly, as shown in FIG. 7( b), the right second surface 82Rf on which the right rotation restricting portion 82R is formed is disposed closer to the inside of the device body 2 in the longitudinal direction LD than the right first surface 81Rf on which the right positioning portion 81R is formed. The right rotation restricting boss 22R is also disposed closer to the inside of the device body 2 in the longitudinal direction LD than the left positioning boss 21R. This allows the cutout shape forming the right rotation restricting portion 82R, formed on the right second surface 82Rf, to have a relatively small area. Furthermore, because the right positioning portion 81R is disposed upstream of the right rotation restricting portion 82R in the mounting direction AD, the cutout shape forming the right positioning portion 81R, formed on the right first surface 81Rf, also requires a relatively small area. In this way, by reducing the area of ​​the cutout formed in the right side plate frame 74, the rigidity of the right side plate frame 74 can be maintained.

[0051] Maintaining the rigidity of the left and right plate frames 73, 74 improves the positioning accuracy of the process unit 20 relative to the apparatus body 2. Furthermore, since there is no need to make the left and right plate frames 73, 74 thick in order to increase the rigidity of the left and right plate frames 73, 74, it is possible to reduce weight and costs.

[0052] 8 is a left side view showing the positioning configuration of the process unit 20 by the left side plate frame 73. As shown in FIG. 8, the left positioning portion 81L has surfaces 81La and 81Lc that face each other in the Z direction, and a surface 81Lb that connects these surfaces 81La and 81Lc and faces the left positioning boss 21L in the installation direction AD. In addition, the left rotation restricting portion 82L has surfaces 82La and 82Lb that face each other in the Z direction.

[0053] The width of the left positioning portion 81L in the Z direction, i.e., the distance between the surfaces 81La and 81Lc, is width Z1. The width of the left rotation restricting portion 82L in the Z direction, i.e., the distance between the surfaces 82La and 82Lb, is width Z2. The left rotation restricting portion 82L is disposed so as to overlap at least a portion of the left positioning portion 81L in the Z direction. This causes the movement trajectories of the left positioning boss 21L and the left rotation restricting boss 22L in the Z direction to overlap when the process unit 20 is attached to the device body 2, thereby minimizing the area within the device body 2 that must be avoided by these movement trajectories. This allows for effective use of the space within the device body 2 and allows the image forming apparatus 1 to be made more compact.

[0054] Furthermore, since the left positioning portion 81L and the left rotation restricting portion 82L are both provided on the single left side plate frame 73 made of a sheet metal member, component intersections can be suppressed and the positioning accuracy of the process unit 20 can be improved.

[0055] 8 is the same on the right side plate frame 74 side, and provides the same effects. In the present embodiment, the axial centers of the left positioning boss 21L and the left rotation restricting boss 22L are at the same position in the Z direction, but this is not limiting.

[0056] <Second embodiment> Next, a second embodiment of the present invention will be described, in which the configurations of the left second surface 82Lf and the right second surface 82Rf of the first embodiment are modified. Therefore, configurations similar to those of the first embodiment will be omitted from the illustrations or will be described with the same reference numerals in the drawings.

[0057] Fig. 9 is a perspective view showing the image forming apparatus 1B according to the second embodiment before the process unit 20B as a detachable unit is attached. Fig. 10(a) is a rear view and an enlarged view showing the positioning configuration of the process unit 20B by the left side plate frame 73B, and Fig. 10(b) is a rear view and an enlarged view showing the positioning configuration of the process unit 20B by the right side plate frame 74B.

[0058] As shown in FIG. 9, the process unit 20B has a left side surface 30L and a right side surface 30R as end surfaces in the longitudinal direction LD, and surfaces 31L and 31R facing downstream in the installation direction AD. A left rotation restriction boss 22BL is provided on surface 31L as a second positioned portion, and a right rotation restriction boss 22BR is provided on surface 31R. The left rotation restriction boss 22BL and the right rotation restriction boss 22BR extend downstream in the installation direction AD. The left positioning boss 21BL and the right positioning boss 21BR are located upstream of the left rotation restriction boss 22BL and the right rotation restriction boss 22BR, respectively, in the installation direction AD.

[0059] The apparatus body 2B of the image forming apparatus 1B has a left plate frame 73B and a right plate frame 74B made of sheet metal members, and these left plate frame 73B and right plate frame 74B face each other with a gap in the longitudinal direction LD.

[0060] As shown in FIGS. 9 and 10(a), the left side plate frame 73B has a left first surface 81Lf extending in the installation direction AD (Y direction) and the Z direction, and a left second surface 82BLf extending in the longitudinal direction LD and the Z direction. The left second surface 82BLf as the second surface is positioned more inward of the device body 2 in the longitudinal direction LD than the left first surface 81Lf by bending the left first surface 81Lf. In other words, the left first surface 81Lf and the left second surface 82BLf are not coplanar. In this embodiment, the left second surface 82BLf is configured as a surface parallel to the longitudinal direction LD and the Z direction, but is not limited to this. For example, the left second surface 82Lf may be a curved surface along the longitudinal direction LD and the Z direction.

[0061] The left second surface 82BLf is formed with a left rotation restricting portion 82BL with which the left rotation restricting boss 22BL can engage, and the left rotation restricting portion 82BL as a second positioning portion is composed of a hole that penetrates in the installation direction AD. The left rotation restricting portion 82BL also has surfaces 82BLa and 82BLb that can engage with the left rotation restricting boss 22BL in the Z direction. Because the left second surface 82BLf is located more inward of the device body 2 than the left first surface 81Lf in the longitudinal direction LD, the left rotation restricting portion 82BL is located at a different position from the left positioning portion 81BL in the longitudinal direction LD.

[0062] Similarly, as shown in FIGS. 9 and 10(b), the right side plate frame 74B has a right first surface 81Rf extending along the installation direction AD (Y direction) and the Z direction, and a right second surface 82BRf extending along the longitudinal direction LD and the Z direction. The right second surface 82BRf is disposed more inward of the device body 2 than the right first surface 81Rf in the longitudinal direction LD by bending the right first surface 81Rf. In other words, the right first surface 81Rf and the right second surface 82Rf are not coplanar. In this embodiment, the right first surface 81Rf and the right second surface 82Rf are configured as surfaces parallel to the installation direction AD (Y direction) and the Z direction, but are not limited thereto. For example, the right second surface 82Rf may be a curved surface along the installation direction AD (Y direction) and the Z direction.

[0063] The right second surface 82BRf is formed with a right rotation restricting portion 82BR with which the right rotation restricting boss 22BR can engage, and the right rotation restricting portion 82BR is composed of a hole that penetrates in the installation direction AD. The right rotation restricting portion 82BR also has surfaces 82BRa and 82BRb that can engage with the right rotation restricting boss 22BR in the Z direction. Because the right second surface 82BRf is located more inward of the device body 2 than the right first surface 81Rf in the longitudinal direction LD, the right rotation restricting portion 82BR is located at a different position from the right positioning portion 81BR in the longitudinal direction LD.

[0064] 10A to 11 are perspective views of the image forming apparatus 1B with the process unit 20B attached. As shown in FIG. 11, when the process unit 20B is attached to the apparatus main body 2B, a biasing mechanism (not shown) biases the process unit 20B from the rear side toward the front side. When the process unit 20B is attached to the apparatus main body 2B, the left positioning boss 21L and the left rotation restricting boss 22BL of the process unit 20B engage with the left positioning portion 81L and the left rotation restricting portion 82BL of the left side plate frame 73B, respectively. Similarly, when the process unit 20B is attached to the apparatus main body 2B, the right positioning boss 21R and the right rotation restricting boss 22BR of the process unit 20B engage with the right positioning portion 81R and the right rotation restricting portion 82BR of the right side plate frame 74B, respectively.

[0065] The process unit 20B is positioned in the installation direction AD by the left positioning boss 21L and the right positioning boss 21R engaging with the left positioning portion 81L and the right positioning portion 81R, respectively. Furthermore, the left rotation restriction boss 22BL and the right rotation restriction boss 22BR engage with the right rotation restriction portion 82BR and the right rotation restriction portion 82BR, respectively, so that rotational movement of the process unit 20B about the left positioning boss 21L and the right positioning boss 21R is restricted. In other words, the process unit 20B is positioned in the Z direction.

[0066] As in the first embodiment, the left second surface 82BLf on which the left rotation restricting portion 82BL is formed is disposed closer to the inside of the device body 2 in the longitudinal direction LD than the left first surface 81Lf on which the left positioning portion 81L is formed. The left rotation restricting boss 22BL is also disposed closer to the inside of the device body 2 in the longitudinal direction LD than the left positioning boss 21L. This allows the hole shape forming the left rotation restricting portion 82BL, formed on the left second surface 82BLf, to have a relatively small area. Furthermore, because the left positioning portion 81L is disposed upstream of the left rotation restricting portion 82BL in the mounting direction AD, the notch shape forming the left positioning portion 81L, formed on the left first surface 81Lf, also requires a relatively small area. In this way, by reducing the area of ​​the notches and holes formed in the left side plate frame 73B as a frame member, the rigidity of the left side plate frame 73B can be maintained.

[0067] Similarly, by reducing the area of ​​the notches and holes formed in the right side frame 74B, the rigidity of the right side frame 74B can be maintained. By maintaining the rigidity of the left side frame 73B and the right side frame 74B, the positioning accuracy of the process unit 20B relative to the apparatus body 2B can be improved. Furthermore, since there is no need to make the left side frame 73B and the right side frame 74B thick in order to increase the rigidity of the left side frame 73B and the right side frame 74B, weight and costs can be reduced.

[0068] <Third embodiment> Next, a third embodiment of the present invention will be described, in which the fixing unit 9 is configured to be detachable from the apparatus main body 2C, instead of the process unit 20 of the first embodiment. Therefore, the same components as those in the first embodiment will not be shown in the drawings or will be described with the same reference numerals in the drawings.

[0069] Fig. 12 is a perspective view showing an image forming apparatus 1C according to the third embodiment before a detachable unit and a fixing unit 9 serving as a fixing section are attached. As shown in Fig. 12, the fixing unit 9 has a left side surface 41L and a right side surface 41R as end surfaces in a longitudinal direction LD parallel to the X direction. A left positioning boss 21L and a left rotation restricting boss 22L are provided on the left side surface 41L, and a right positioning boss 21R and a right rotation restricting boss 22R are similarly provided on the right side surface 41R (see Fig. 7(b)).

[0070] FIG. 13 is a left side view showing the positioning configuration of the fixing unit 9 by the left side plate frame 73. As shown in FIG. 13, when the fixing unit 9 is attached to the apparatus body 2, a biasing mechanism (not shown) biases the fixing unit 9 from the rear side toward the front side. When the fixing unit 9 is attached to the apparatus body 2C, the left positioning boss 21L and the left rotation restricting boss 22L of the fixing unit 9 engage with the left positioning portion 81L and the left rotation restricting portion 82L of the left side plate frame 73, respectively. Similarly, when the fixing unit 9 is attached to the apparatus body 2, the right positioning boss 21R and the right rotation restricting boss 22R of the fixing unit 9 engage with the right positioning portion 81R and the right rotation restricting portion 82R of the right side plate frame 74, respectively.

[0071] The fixing unit 9 is positioned in the installation direction AD by the left positioning boss 21L and the right positioning boss 21R engaging with the left positioning portion 81L and the right positioning portion 81R, respectively. Furthermore, the fixing unit 9 is restricted from rotational movement about the left positioning boss 21L and the right positioning boss 21R by the left rotation restricting boss 22L and the right rotation restricting boss 22R engaging with the left rotation restricting portion 82L and the right rotation restricting portion 82R, respectively. In other words, the fixing unit 9 is positioned in the Z direction.

[0072] The left positioning boss 21L, the left rotation restriction boss 22L, the right positioning boss 21R, and the right rotation restriction boss 22R have the same configurations as those in the first embodiment, and therefore their explanations will be omitted. The present embodiment also provides the same effects as those in the first embodiment.

[0073] <Other embodiments> In any of the above-described embodiments, the process units 20, 20B and the fixing unit 9 are mounted from the rear side to the front side of the apparatus main bodies 2, 2B, 2C, but this is not limitative. In other words, the mounting direction AD does not have to be along the Y direction.

[0074] In addition, in all of the above-described embodiments, the process units 20, 20B and the fixing unit 9 are provided with boss-shaped positioning bosses and rotation restricting bosses, but this is not limiting. In other words, the process units 20, 20B and the fixing unit 9 may be provided with positioning portions and rotation restricting portions that are not boss-shaped.

[0075] In the first and second embodiments, the process units 20 and 20B each having the photosensitive drum 11, the developing roller 12, the storage section 18, etc. are configured to be detachable from the apparatus main body 2 and 2B, but this is not limiting. For example, instead of the process unit, a developing unit having only the storage section 18 for storing toner, or a developing unit having the developing roller 12 and the storage section 18 without the photosensitive drum 11, may be used. may be configured so as to be positionable on the device main body 2 by the above-mentioned positioning configuration.

[0076] In addition, in all of the above-described embodiments, the left positioning portion 81L is disposed upstream of the left rotation restricting portions 82L, 82BL in the mounting direction AD, but this is not limiting. For example, the left positioning portion 81L may be disposed downstream of the left rotation restricting portions 82L, 82BL in the mounting direction AD. In this case, it is preferable that the left positioning portion 81L is provided on the second left surfaces 82Lf, 82BLf, and the left rotation restricting portion 82L is provided on the first left surface 81Lf.

[0077] In addition, although the above-described embodiments have been described using electrophotographic image forming apparatuses 1, 1B, and 1C, the present invention is not limited to this. For example, the present invention can also be applied to an inkjet image forming apparatus that forms an image on a sheet by ejecting ink liquid from nozzles. [Explanation of symbols]

[0078] 1, 1B, 1C: image forming apparatus / 2, 2B, 2C: apparatus body / 9: detachable unit, fixing unit (fixing unit) / 18: toner storage unit (storage unit) / 20, 20B: detachable unit (process unit) / 21L, 221L: first positioned portion (left positioning boss) / 22L, 22BL, 222L: second positioned portion (left rotation restriction boss) / 30L: end surface (left side surface) / 31L: surface / 41L : End face (left side) / 73, 73B: Frame member (left side plate frame) / 81L, 281L: First positioning part (left positioning part) / 81Lf: First surface (left first surface) / 82L, 82BL, 282L: Second positioning part (left rotation restriction part) / 82Lf, 82BLf: Second surface (left second surface) / 200: Receiving port (supply port) / AD: Mounting direction / LD: Second direction (longitudinal direction) / Z: First direction (direction)

Claims

1. In an image forming apparatus for forming an image on a sheet, a unit including a photosensitive drum rotatable about a rotation axis extending in a rotation axis direction intersecting with a gravity direction, a developing roller that supplies toner to the photosensitive drum, and a first protrusion and a second protrusion that protrude from an end surface of the unit in the rotation axis direction; an apparatus main body to which the unit is detachably attached, the first protrusion has a first abutment portion including a first abutment surface; the second protrusion has a second abutment portion including a second abutment surface, a tip end of the second protrusion is provided more inward of the unit than a tip end of the first protrusion in the rotation axis direction, the unit is configured to be attached to the device body from a first position where a part of the unit is located outside the device body along an attachment direction that intersects both the rotation axis direction and the gravity direction, to a second position where the unit is located inside the device body and is positioned relative to the device body in the attachment direction, the device body has a side plate portion provided opposite the end surface of the unit, the side plate portion of the device body has a first contact portion and a second contact portion arranged in the mounting direction, the first contacted portion has a first contacted surface that contacts the first contact surface of the first contact portion of the unit when the unit is located at the second position, the second contacted portion has a second contacted surface that contacts the second contact surface of the second contact portion of the unit when the unit is located at the second position, the second abutment surface is disposed downstream of the first abutment surface in the mounting direction and further inward of the device body than the first abutment surface in the rotation axis direction, the second contact surface is disposed downstream of the first contact surface in the mounting direction and further inward of the unit than the first contact surface in the rotation axis direction. An image forming apparatus characterized by:

2. The side plate portion has a sheet metal member including a constriction portion that is retracted toward the inside of the device body in the direction of the rotation axis so that the second abutment surface is located more toward the inside of the device body than the first abutment surface in the direction of the rotation axis.

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

3. The sheet metal member has a first notch portion and a second notch portion, the first contact portion is exposed from the sheet metal member through the first cutout portion, the second abutment portion is exposed from the sheet metal member through the second cutout portion; 3. The image forming apparatus according to claim 2, wherein the image forming apparatus is a recording medium.

4. Further comprising a fixing unit for fixing the image on the sheet to the sheet; the first contact portion and the second contact portion are located below the fixing portion; 4. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

Images