Image forming apparatus

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 for forming 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-shaped grooves are formed in the side plates. The process cartridge is positioned by engaging a first positioning portion and a second positioning portion of the process cartridge with the ends of these grooves. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-112731 A 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 supporting the process cartridge is reduced, the positioning accuracy of the process cartridge may be reduced.

[0005] SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to provide an image forming apparatus with improved positioning accuracy of a detachable unit relative to the apparatus body. [Means for solving the problem]

[0006] The present invention relates to an image forming apparatus for forming an image on a sheet, the apparatus comprising: an apparatus main body; and a detachable unit that is attached to the apparatus main body in an attachment direction and is detachably supported by the apparatus main body, the detachable unit having a first positioned portion and a second positioned portion that are respectively provided at ends of the detachable unit in a second direction that intersects both the attachment direction and a first direction that intersects the attachment direction, the apparatus main body having a frame member that is provided on the end side of the detachable unit in the second direction and detachably supports the detachable unit and is made of a sheet metal member, the frame member having a first positioning portion that is engageable with the first positioned portion. the second surface has a first surface extending in the mounting direction and the first direction, and a second surface having a second positioning portion engageable with the second positioned portion and arranged parallel to the first surface, the second surface is disposed in a position closer to a center of the detachable unit in the second direction than the first surface, one of the first positioning portion and the second positioning portion positions the detachable unit in the mounting direction, and the other of the first positioning portion and the second positioning portion positions the detachable unit in the first direction, and the second positioning portion is a recess formed in the second surface and opening to the upstream side in the mounting direction. The present invention also relates to an image forming apparatus for forming an image on a sheet, the apparatus comprising: an apparatus main body; and a detachable unit that is attached to the apparatus main body in an attachment direction and is detachably supported by the apparatus main body, the detachable unit having a first positioned portion and a second positioned portion that are provided at an end of the detachable unit in a second direction that intersects both the attachment direction and a first direction that intersects the attachment direction, the apparatus main body having a frame member that is provided on the end side of the detachable unit in the second direction and detachably supports the detachable unit and is made of a sheet metal member, the frame member having a first position that can engage with the first positioned portion, the second surface has a positioning portion engageable with the second positioned portion and extends in the first direction and the second direction, the second surface is positioned closer to a center of the detachable unit in the second direction than the first surface, one of the first positioning portion and the second positioning portion positions the detachable unit in the mounting direction, the other of the first positioning portion and the second positioning portion positions the detachable unit in the first direction, and the second positioning portion is a hole portion penetrating the second surface in the mounting direction. Effect of the Invention

[0007] According to the present invention, the positioning accuracy of the detachable unit relative to the main body of the apparatus can be improved. [Brief description of the drawings]

[0008] [Figure 1] 1 is an overall schematic view showing an image forming apparatus according to a first embodiment. [Diagram 2] FIG. 1 is a cross-sectional view showing a configuration of an image forming apparatus. [Diagram 3] FIG. 2A is a perspective view showing an image forming apparatus with a rear cover closed, and FIG. 2B 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. [Diagram 5] 1A is a rear view and an enlarged view showing the positioning configuration of the process unit by the left side plate frame, and FIG. 1B is a rear view and an enlarged view showing the positioning configuration of the process unit by the right side plate frame. [Figure 6] FIG. 1A is an oblique view showing an image forming apparatus with a process unit attached, FIG. 1B is an enlarged view showing a left positioning portion and a left rotation regulating portion, and FIG. 1C is an enlarged view showing a left positioning portion and a left rotation regulating portion for 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 side 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 side plate frame. [Figure 8] FIG. 4 is a left side view showing a positioning configuration of the process unit by the left side plate frame. [Figure 9] FIG. 11 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 side plate frame, and FIG. 1B is a rear view and an enlarged view showing the positioning configuration of the process unit by the right side plate frame. [Figure 11] FIG. 2 is a perspective view showing the image forming apparatus with a process unit attached thereto. [Figure 12] FIG. 13 is a perspective view showing an image forming apparatus according to a third embodiment. [Figure 13] FIG. 4 is a left side view showing a positioning configuration of the process unit by the left side plate frame. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[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 thick paper, plastic films 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 (opposite to the vertical direction) of the image forming apparatus 1 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 rotation axis direction (main scanning direction) of the photosensitive drum 11 described later is referred to as the X direction. The direction that intersects with the X direction and the Z direction is referred to as the Y direction. The X direction, the Y direction, and the Z direction 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 fixed to the device body 2 of the image forming apparatus 1 with screws, and also includes a unit that is removable by a service person.

[0014] The photosensitive drum 11 as an image carrier is a cylindrically shaped photosensitive body. The photosensitive drum 11 of this embodiment has a photosensitive layer formed of a negatively charged organic photosensitive body on a drum-shaped base body formed of aluminum. The photosensitive drum 11 as an image carrier is rotated by a motor in a predetermined direction (direction R in the figure) at a predetermined process speed.

[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 to uniformly charge the surface of the photosensitive drum 11 to a predetermined potential. In this embodiment, the photosensitive drum 11 is charged to a negative polarity 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 be, for example, 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 contained in the storage section 18 as a developer onto the surface of the developing roller 12.

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

[0019] The toner in 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, the one-component developer may contain additives (e.g., wax or silica particles) for adjusting the fluidity and charging performance of the toner. A two-component developer composed of a non-magnetic toner and a magnetic carrier may also be used as the developer. When a magnetic developer is used, for example, a cylindrical developing sleeve with a magnet arranged inside is used as the developer carrier.

[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 to it. The fixing unit 9 includes a heating roller 9a incorporating a fixing heater 9c, and a pressure roller 9b that is in pressure contact with 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 part of the end face on the front side of the image forming apparatus 1, and the front cover 70 covers the circuit board 100. The device 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 (b)), and an exterior cover 71 that constitutes 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 port 15 through which the sheet discharged to the discharge tray 14 passes.

[0022] The process unit 20 is also provided with a replenishing port 200 (see FIG. 4) as a receiving port for receiving toner supplied from the outside. The replenishing port 200 communicates with the storage section 18, and is exposed by opening the discharge tray 14 upward when the process unit 20 is attached to the apparatus body 2. Then, a user can replenishing toner to the storage section 18 through the replenishing port 200 by attaching a replenishing toner container to the exposed replenishing port 200. In this way, the process unit 20 of the present embodiment is configured to be able to replenishing toner to the storage section 18 when attached to the apparatus 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, 121 soldered to the wiring board 101. Conductive wiring is provided on and inside the wiring board 101, so that the electronic components 111, 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, the 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, an 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 charged in advance by the charging roller 17, and an electrostatic latent image is formed on the photosensitive drum 11 by irradiating it with 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 above-mentioned image forming process, the pickup roller 3 of the feeding section 30 feeds out the recording material P supported by the cassette 4. The recording material P is separated into individual sheets by the feeding roller 5a and the separation roller 5b, and conveyed to the conveying roller pair 5c. The recording material P is then conveyed by the conveying roller pair 5c as a conveying section toward the transfer nip N1 formed by the transfer roller 7 and the photosensitive drum 11.

[0027] A transfer voltage is applied to the transfer roller 7 from a high-voltage transfer power supply, and the toner image carried on the photosensitive drum 11 is transferred to 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 when passing through a nip portion between a heating roller 9a and a pressure roller 9b of the fixing unit 9. This causes the toner particles to melt and then adhere, thereby fixing the toner image to the recording material P. The recording material P that has passed through the fixing unit 9 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 the first side, thereby guiding the recording material P to a 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 to the recording material P, the toner remaining on the photosensitive drum 11 is cleaned by a cleaning unit 13.

[0029] As shown in Figures 3(a) and (b), a rear cover 75 that is supported so as to be openable and closable is provided on the rear surface of the image forming apparatus 1. The rear cover 75, which serves as an opening / closing 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 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 a direction along the Y direction.

[0030] In addition, by opening the rear cover 75, the double-sided conveying path 16 (see FIG. 2) is opened. That is, the rear cover 75 is movable between a closed position that covers the double-sided conveying path 16 and an open position that exposes the double-sided conveying path 16 to the outside. This makes it possible to clear a jam that occurs in the double-sided conveying path 16. In addition, by opening a transfer unit (not shown) with the double-sided conveying path 16 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 in a state before the process unit 20 is attached. 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] As shown in Fig. 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 mounting direction AD of the process unit 20.

[0033] The main body 2 of the image forming apparatus 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 FIG. 4 and FIG. 5(a), the left side plate frame 73 as a frame member has a left first surface 81Lf and a left second surface 82Lf extending in a direction along the mounting direction AD (Y direction) and the Z direction. The left second surface 82Lf is disposed inward of the device body 2 by a distance X1 from the left first surface 81Lf in the longitudinal direction LD by drawing the left first surface 81Lf as the first surface. That is, the left first surface 81Lf and the left second surface 82Lf are not on the same plane. In this embodiment, the left second surface 82Lf as the second surface is configured of a surface parallel to the mounting direction AD (Y direction) and the Z direction, but is not limited thereto. For example, the left second surface 82Lf may be a curved surface along the mounting direction AD (Y direction) and the Z direction.

[0035] The left first 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 the first positioning portion is a notch with an open upstream side in the mounting direction AD. The left second 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 the second positioning portion is a U-shaped notch with an open upstream side in the mounting direction AD. Since the left second 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 FIG. 4 and FIG. 5(b), the right side plate frame 74 has a right first surface 81Rf and a right second surface 82Rf extending along the mounting direction AD (Y direction) and the Z direction. The right second surface 82Rf is disposed inward of the device body 2 by a distance X2 from the right first surface 81Rf in the longitudinal direction LD by drawing the right first surface 81Rf. That is, the right first surface 81Rf and the right second surface 82Rf are not on the same plane. In this embodiment, the right first surface 81Rf and the right second surface 82Rf are configured by surfaces parallel to the mounting 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 mounting 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 with an open upstream side in the mounting 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 with an open upstream side in the mounting direction AD. Since 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 right first surface 81Rf and the right second surface 82Rf are provided at a distance X2 apart in the longitudinal direction LD, the right rotation restricting portion 82R is also disposed at a distance X2 apart from the right positioning portion 81R in the longitudinal direction LD. In other words, the right rotation restricting portion 82R is disposed at a position different 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 FIG. 5(a) to FIG. 6(b), when the process unit 20 is attached to the device 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 device 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 device 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 mounting 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 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, restricts the process unit 20 from rotating about the left positioning boss 21L and the right positioning boss 21R. That is, 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 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 in the Z direction. In other words, the left positioning portion 81L positions the process unit 20 in the Z direction together with the left rotation restricting portion 82L.

[0043] Furthermore, when the process unit 20 is attached to the apparatus 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 with respect to the left rotation restricting portion 82L. In other words, the left rotation restricting portion 82L is configured not to position the process unit 20 in the attachment direction AD when the process unit 20 is positioned in the attachment direction AD by the left positioning portion 81L. This allows the process unit 20 to be 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 their explanation will be omitted.

[0045] Fig. 6(c) is an enlarged view showing the left positioning portion 281L and the left rotation restricting portion 282L according to a modified example 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 is not limited thereto. 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, 253 face each other in the Z direction. When the process unit 20 is attached to the apparatus body 2, the left positioning boss 221L 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, 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 mounting direction AD by the left positioning portion 81L, the left rotation restricting boss 222L 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 mounting direction AD with respect to the left rotation restricting portion 282L. In other words, the left rotation restricting portion 282L is configured not to position the process unit 20 in the mounting direction AD when the process unit 20 is positioned in the mounting direction AD by the left positioning portion 281L. This allows the process unit 20 to be reliably positioned in the mounting 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. 7(a), the left second surface 82Lf on which the left rotation restricting portion 82L is formed is disposed inside the device body 2 in the longitudinal direction LD with respect to the left first surface 81Lf on which the left positioning portion 81L is formed. The left rotation restricting boss 22L is also disposed inside the device body 2 in the longitudinal direction LD with respect to the left positioning boss 21L. As a result, the cutout shape constituting the left rotation restricting portion 82L formed on the left second surface 82Lf requires a relatively small area. In addition, since the left positioning portion 81L is disposed upstream of the left rotation restricting portion 82L in the mounting direction AD, the cutout shape constituting 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 cutout formed in the left side plate frame 73, 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 inside the device body 2 in the longitudinal direction LD with respect to the right first surface 81Rf on which the right positioning portion 81R is formed. The right rotation restricting boss 22R is also disposed inside the device body 2 in the longitudinal direction LD with respect to the left positioning boss 21R. As a result, the cutout shape constituting the right rotation restricting portion 82R formed on the right second surface 82Rf requires a relatively small area. In addition, since the right positioning portion 81R is disposed upstream of the right rotation restricting portion 82R in the mounting direction AD, the cutout shape constituting 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 side frame 73 and the right side frame 74 can improve the positioning accuracy of the process unit 20 with respect to the apparatus body 2. Also, since there is no need to make the left side frame 73 and the right side frame 74 thick in order to increase the rigidity of the left side frame 73 and the right side frame 74, it is possible to reduce weight and costs.

[0052] Fig. 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, 81Lc facing each other in the Z direction and a surface 81Lb connecting these surfaces 81La, 81Lc and facing the left positioning boss 21L in the installation direction AD. In addition, the left rotation restricting portion 82L has surfaces 82La, 82Lb facing 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 part 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 when the process unit 20 is attached to the device body 2 to overlap, and the area in the device body 2 that avoids the movement trajectories can be suppressed. This makes it possible to effectively utilize the space in the device body 2 and to reduce the size of the image forming device 1.

[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 intersection 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 limited to this.

[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 changed. Therefore, configurations similar to those of the first embodiment will be described by omitting illustrations or by assigning the same reference numerals in the drawings.

[0057] Fig. 9 is a perspective view showing an image forming apparatus 1B according to the second embodiment before a process unit 20B as a removable 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, 31R facing downstream in the mounting direction AD. A left rotation restriction boss 22BL as a second positioned portion is provided on the surface 31L, and a right rotation restriction boss 22BR is provided on the surface 31R. The left rotation restriction boss 22BL and the right rotation restriction boss 22BR extend downstream in the mounting direction AD. The left positioning boss 21BL and the right positioning boss 21BR are disposed upstream of the left rotation restriction boss 22BL and the right rotation restriction boss 22BR, respectively, in the mounting direction AD.

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

[0060] As shown in FIG. 9 and FIG. 10(a), the left side plate frame 73B has a left first surface 81Lf extending in the direction along the mounting direction AD (Y direction) and the Z direction, and a left second surface 82BLf extending in the direction along the longitudinal direction LD and the Z direction. The left second surface 82BLf as the second surface is disposed on the inside of the device body 2 in the longitudinal direction LD than the left first surface 81Lf by bending the left first surface 81Lf. That is, the left first surface 81Lf and the left second surface 82BLf are not on the same plane. In this embodiment, the left second surface 82BLf is configured of a surface parallel to the longitudinal direction LD and the Z direction, but is not limited thereto. 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 portion penetrating in the mounting 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. Since the left second surface 82BLf is disposed on the inside of the device body 2 relative to the left first surface 81Lf in the longitudinal direction LD, the left rotation restricting portion 82BL is disposed at a position different from the left positioning portion 81BL in the longitudinal direction LD.

[0062] Similarly, as shown in FIG. 9 and FIG. 10(b), the right side plate frame 74B has a right first surface 81Rf extending along the mounting 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 on the inside of the device body 2 in the longitudinal direction LD, by bending the right first surface 81Rf. That is, the right first surface 81Rf and the right second surface 82Rf are not on the same plane. In this embodiment, the right first surface 81Rf and the right second surface 82Rf are configured by surfaces parallel to the mounting 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 mounting 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 portion penetrating in the mounting direction AD. The right rotation restricting portion 82BR also has surfaces 82BRa and 82BRb with which the right rotation restricting boss 22BR can engage in the Z direction. Since the right second surface 82BRf is disposed on the inside of the device body 2 relative to the right first surface 81Rf in the longitudinal direction LD, the right rotation restricting portion 82BR is disposed at a position different from the right positioning portion 81BR in the longitudinal direction LD.

[0064] 10(a) to 11 are perspective views showing 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, the process unit 20B is urged from the rear side toward the front side by an urging mechanism (not shown). 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 mounting 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 restricting boss 22BL and the right rotation restricting boss 22BR engage with the right rotation restricting portion 82BR and the right rotation restricting portion 82BR, respectively, so that the process unit 20B is restricted in its rotational movement about the left positioning boss 21L and the right positioning boss 21R. 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 inside the device body 2 in the longitudinal direction LD with respect to the left first surface 81Lf on which the left positioning portion 81L is formed. The left rotation restricting boss 22BL is also disposed inside the device body 2 in the longitudinal direction LD with respect to the left positioning boss 21L. This allows the hole shape constituting the left rotation restricting portion 82BL formed on the left second surface 82BLf to have a relatively small area. In addition, since the left positioning portion 81L is disposed upstream of the left rotation restricting portion 82BL in the mounting direction AD, the notch shape constituting 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 notch or hole 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 with respect to the apparatus body 2B can be improved. Also, since there is no need to form 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, for example, weight reduction and cost reduction can be achieved.

[0068] <Third embodiment> Next, a third embodiment of the present invention will be described, in which a fixing unit 9 is configured to be detachable from an apparatus main body 2C, instead of the process unit 20 of the first embodiment. Therefore, the same configurations as those of the first embodiment will be omitted from the illustrations or will be described by using 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] 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 device body 2, the fixing unit 9 is urged from the rear side toward the front side by an urging mechanism (not shown). When the fixing unit 9 is attached to the device 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 device 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 mounting 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. Also, the fixing unit 9 is restricted in 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. That is, 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 the description thereof will be omitted. Also in this embodiment, the same effects as those in the first embodiment are achieved.

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

[0074] In addition, in any 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 the present invention is not limited to this. In other words, the process units 20, 20B and the fixing unit 9 may be provided with positioning parts and rotation restricting parts that are not boss-shaped.

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

[0076] In addition, in any 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 limited thereto. 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 left second surfaces 82Lf, 82BLf, and the left rotation restricting portion 82L is provided on the left first surface 81Lf.

[0077] In addition, in each of the above-described embodiments, the electrophotographic image forming apparatuses 1, 1B, and 1C are used for the explanation, but the present invention is not limited thereto. For example, the present invention can be applied to an inkjet image forming apparatus that forms an image on a sheet by ejecting ink liquid from a nozzle. [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 (first left surface) / 82L, 82BL, 282L: Second positioning part (left rotation restriction part) / 82Lf, 82BLf: Second surface (second left 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