Image forming apparatus

Abstract

The present invention provides an image forming apparatus with improved positioning accuracy of the detachable unit relative to the main body of the apparatus. [Solution] An image forming apparatus for forming an image on a sheet comprises an apparatus body and a detachable unit mounted on the apparatus body in the mounting direction and detachably supported on the apparatus body, wherein the detachable unit has a first positioning portion and a second positioning portion, and the apparatus body has a single frame member which includes a first positioning portion that positions the detachable unit in the mounting direction when the first positioning portion engages with it, and a second positioning portion that positions the detachable unit in a first direction intersecting the mounting direction when the second positioning portion engages with it, wherein the second positioning portion is positioned differently from the first positioning portion in the second direction intersecting the mounting direction and the first direction.

Description

Technical Field

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

Background Art

[0002] Conventionally, an image forming apparatus has been proposed that has a process cartridge detachably supported by a device main body and is capable of exchanging the process cartridge (see Patent Document 1). This device main body has a pair of side plates on the left and right, and two rail-shaped grooves are formed in the side plates. By engaging the first positioning portion and the second positioning portion of the process cartridge with the ends of these grooves, the process cartridge is positioned.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, since the side plates described in Patent Document 1 have two large rail-shaped grooves formed on the same plane, there is a risk of reduced rigidity. When the rigidity of the side plate that supports the process cartridge decreases, there is a risk that the positioning accuracy of the process cartridge will decrease.

[0005] Therefore, an object of the present invention is to provide an image forming apparatus with improved positioning accuracy of a unit with respect to a device main body.

Means for Solving the Problems

[0006] The present invention relates to an image forming apparatus for forming an image on a sheet, comprising: a unit having a photosensitive drum rotatable about a rotation axis extending in a direction perpendicular to the direction of gravity; a developing roller for supplying toner to the photosensitive drum; and a first projection and a second projection projecting from the end face of the unit in the direction perpendicular to the direction of rotation; and an apparatus body to which the unit is detachably attached, wherein the first projection has a first contact portion including a first contact surface, and the second projection has a second contact portion including a second contact surface, and the tip of the second projection is provided further inside the unit than the tip of the first projection in the direction perpendicular to the direction of rotation, and the unit is positioned relative to the apparatus body in the mounting direction, from a first position in which a part of the unit is located outside the apparatus body along a mounting direction perpendicular to both the direction perpendicular to the direction of rotation and the direction of gravity, to a position in which the unit is located inside the apparatus body and relative to the apparatus body in the mounting direction. The device is configured to be attached to the main body of the device to a second position, the main body of the device having a side plate portion provided opposite to the end face of the unit, the side plate portion of the main body of the device having a first contact portion and a second contact portion arranged in the mounting direction, the first contact portion having a first contact surface that contacts the first contact surface of the first contact portion of the unit when the unit is in the second position, the second contact portion having a second contact surface that contacts the second contact surface of the second contact portion of the unit when the unit is in the second position, the second contact surface being positioned downstream of the first contact surface in the mounting direction and inside the main body of the device compared to the first contact surface in the rotation axis direction, and the second contact surface being positioned downstream of the first contact surface in the mounting direction and inside the unit compared to the first contact surface in the rotation axis direction. [Effects of the Invention]

[0007] According to the present invention, the positioning accuracy of the unit relative to the device body can be improved. [Brief explanation of the drawing]

[0008] [Figure 1]A schematic diagram showing an image forming apparatus according to the first embodiment. [Figure 2] A cross-sectional view showing the configuration of an image forming apparatus. [Figure 3] (a) is a perspective view showing the image forming apparatus with the rear cover closed, and (b) is a perspective view showing the image forming apparatus with the rear cover open. [Figure 4] A perspective view showing the image forming apparatus before the process unit is installed. [Figure 5] (a) is a rear view and enlarged view showing the positioning configuration of the process unit by the left panel frame, and (b) is a rear view and enlarged view showing the positioning configuration of the process unit by the right panel frame. [Figure 6] (a) is a perspective view showing an image forming apparatus with a process unit installed, (b) is an enlarged view showing the left positioning unit and left rotation restricting unit, and (c) is an enlarged view showing the left positioning unit and left rotation restricting unit according to a modified example of the first embodiment. [Figure 7] (a) is a cross-sectional view parallel to the XY plane showing the positioning configuration of the process unit by the left plate frame, and (b) 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] A left side view showing the positioning configuration of the process unit by the left side plate frame. [Figure 9] A perspective view showing an image forming apparatus according to a second embodiment. [Figure 10] (a) is a rear view and enlarged view showing the positioning configuration of the process unit by the left panel frame, and (b) is a rear view and enlarged view showing the positioning configuration of the process unit by the right panel frame. [Figure 11] A perspective view showing an image forming apparatus with a process unit installed. [Figure 12] A perspective view showing an image forming apparatus according to a third embodiment. [Figure 13] A left side view showing the positioning configuration of the process unit by the left side plate frame. [Modes for carrying out the invention]

[0009] The embodiments for carrying out this invention will be described in detail below with reference to the drawings, based on examples. However, the dimensions, materials, shapes, and relative arrangements of the components described in these embodiments should be appropriately modified depending on the configuration of the device to which the invention is applied and various conditions. In other words, the scope of this invention is not intended to be limited to the following embodiments.

[0010] <First Embodiment> Figure 1 is a perspective view showing an image forming apparatus 1 according to a first embodiment. Figure 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 plain paper and cardboard, plastic films such as overhead projector sheets, specially shaped sheets such as envelopes and index paper, and cloth.

[0011] Furthermore, in the following description, the height direction of the image forming apparatus 1 when it is installed on a horizontal surface (the direction opposite to the vertical direction) will be referred to as the Z direction. The direction that intersects the Z direction and is parallel to the rotation axis direction (main scanning direction) of the photosensitive drum 11, which will be described later, will be referred to as the X direction. The direction that intersects the X direction and the Z direction will be referred to as the Y direction. Preferably, the X direction, Y direction and Z direction intersect each other perpendicularly. Also, for convenience, in the X direction, the positive side will be referred to as the right side and the negative side as the left side, in the Y direction, the positive side will be referred to as the front side and the negative side as the rear side, and in the Z direction, the positive side will be referred to as the upper side and the negative side as the lower side.

[0012] [Overall structure] As shown in Figures 1 and 2, the image forming apparatus 1 includes an image forming unit 40 for forming a toner image on a recording material, a feeding unit 30 for feeding the recording material P, a fixing unit 9 for fixing the toner image formed by the image forming unit 40 onto the recording material, and a pair of discharge rollers 10.

[0013] The image forming unit 40 includes a scanner unit 50, an electrophotographic process unit 20, and a transfer roller 7 that transfers the toner image formed on the photosensitive drum 11 of the process unit 20 to a recording material P as a sheet. The process unit 20 includes a photosensitive drum 11, a cleaning unit 13, a charging roller 17, a developing roller 12, and a storage unit 18 that stores toner, which are arranged around the photosensitive drum 11. Note that the process unit 20 may be screwed to the apparatus main body 2 of the image forming apparatus 1 and includes those that can be removed by a service technician.

[0014] The photosensitive drum 11 as an image carrier is a cylindrical photoreceptor. The photosensitive drum 11 of the present embodiment has a photosensitive layer formed of a negatively chargeable organic photoreceptor on a drum-shaped substrate formed of aluminum. Further, the photosensitive drum 11 as an image carrier is rotationally driven 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 contact force to form a charging portion. Further, by applying a desired charging voltage by a charging high-voltage power supply, the surface of the photosensitive drum 11 is uniformly charged to a predetermined potential. In the present embodiment, the photosensitive drum 11 is charged to a negative polarity by the charging roller 17.

[0016] The scanner unit 50 scans and exposes the surface of the photosensitive drum 11 by irradiating the photosensitive drum 11 with laser light corresponding to image information input from an external device using a polygon mirror. By this exposure, an electrostatic latent image corresponding to the image information is formed on the surface of the photosensitive drum 11. Note that the scanner unit 50 is not limited to a laser scanner device, and 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 may be employed.

[0017] The developing roller 12 is rotatably supported by a storage section 18, which serves as a toner storage section. The developing roller 12 is also positioned opposite the photosensitive drum 11. The storage section 18 may also be provided with a supply roller that applies the toner, which is stored in the storage section 18, to the surface of the developing roller 12.

[0018] The process unit 20, which serves as the attachment / detachment unit in this embodiment, employs a contact development method. Specifically, the toner layer supported on the developing roller 12 comes into contact with the photosensitive drum 11 in the 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 supported on the developing roller 12 is transferred from the developing roller 12 to the drum surface according to the potential distribution on the surface of the photosensitive drum 11, thereby developing an electrostatic latent image into a toner image.

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

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

[0021] The feeding unit 30 includes a cassette 4 on which 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 front end face of the image forming apparatus 1, and the front cover 70 covers the circuit board 100. The main body 2 of the image forming apparatus 1 has a housing 72. The housing 72 includes a front cover 70, an output tray 14, a rear cover 75 (see Figures 3(a) and 3(b)), and an exterior cover 71 which constitutes the exterior of the image forming apparatus 1 other than the front cover 70, the output tray 14, and the rear cover 75. The housing 72 has an output port 15 through which the sheet to be output to the output tray 14 passes.

[0022] Furthermore, the process unit 20 is provided with a replenishment port 200 (see Figure 4) which serves as an inlet for receiving toner supplied from an external source. The replenishment port 200 communicates with the storage section 18 and is exposed when the discharge tray 14 is opened upwards while the process unit 20 is mounted on the device body 2. The user can then replenish toner to the storage section 18 through the replenishment port 200 by attaching a toner container to the exposed replenishment port 200. Thus, the process unit 20 of this embodiment is configured to be able to replenish toner to the storage section 18 while mounted on the device body 2.

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

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

[0025] Next, the image forming operation of the image forming apparatus 1 will be described. When an image forming command is input to the image forming apparatus 1, the image forming process by the image forming unit 40 is started 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 when the laser light is irradiated. Subsequently, this 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 formation process described above, the pickup roller 3 of the feeding unit 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 transported to the transport roller pair 5c. The recording material P is then transported by the transport roller pair 5c, which acts as the transport unit, 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 the transfer high-voltage power supply, and the toner image supported on the photosensitive drum 11 is transferred to the recording material P, which is transported by the transport roller pair 5c. The recording material P, on which the toner image has been transferred, is transported to the fixing unit 9, where the toner image is heated and pressurized as it passes through the nip between the heating roller 9a and the pressure roller 9b of the fixing unit 9. This melts the toner particles, which then solidify, fixing the toner image to the recording material P. The recording material P that has passed through the fixing unit 9 is discharged from the discharge port 15 by the discharge roller pair 10 to the outside of the image forming apparatus 1 (outside the machine) and loaded onto the discharge tray 14.

[0028] When forming an image on both sides of the recording material P, the discharge roller pair 10 guides the recording material P to the double-sided transport path 16 by switching back the recording material P on which the image has been formed on the first side. The recording material P guided to the double-sided transport path 16 is then transported again toward the transfer roller 7 by the double-sided transport roller pair 5d. After an image is formed on the second side of the recording material P by the transfer roller 7, it is discharged from the machine by the discharge roller pair 10. After the toner image has been transferred to 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), the rear of the image forming apparatus 1 is provided with a rear cover 75 that is supported to be openable and closable. The rear cover 75, acting as an opening and 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 mounted to the apparatus body 2 in the mounting direction AD shown in Figure 4, and can be removed in the removal direction opposite to the mounting direction AD. The mounting direction AD is along the Y direction.

[0030] Furthermore, when the rear cover 75 is opened, the double-sided transport path 16 (see Figure 2) is opened. In other words, the rear cover 75 is movable between a closed position that covers the double-sided transport path 16 and an open position that exposes the double-sided transport path 16 to the outside. This makes it possible to eliminate jams that occur in the double-sided transport path 16. Also, when the double-sided transport path 16 is in the open position, when the transfer unit (not shown) is opened, the transport path 19 (see Figure 2) through which the sheet transported by the transport roller pair 5c passes is opened.

[0031] [Process unit positioning configuration] Next, the positioning configuration of the process unit 20 will be described using 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 enlarged view showing the positioning configuration of the process unit 20 by the left plate frame 73, and Figure 5(b) is a rear view and enlarged view showing the positioning configuration of the process unit 20 by the right plate frame 74.

[0032] As shown in Figure 4, the process unit 20 has a left side 30L and a right side 30R as end faces in the longitudinal direction LD parallel to the X direction. The left side 30L is provided with a left positioning boss 21L as a first positioning part and a left rotation restricting boss 22L as a second positioning part, and the right side 30R is provided with a right positioning boss 21R and a right rotation restricting boss 22R (see Figure 7(b)). The left positioning boss 21L and the right positioning boss 21R are positioned upstream of the left rotation restricting boss 22L and the right rotation restricting 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 plate frame 73 and a right plate frame 74 made of sheet metal members, and these left plate frame 73 and right plate frame 74 face each other with a gap in the longitudinal direction LD, which is the second direction.

[0034] As shown in Figures 4 and 5(a), the left plate frame 73, as a frame member, has a left first surface 81Lf and a left second surface 82Lf that extend in directions along the mounting direction AD (Y direction) and the Z direction. The left second surface 82Lf is positioned further inward from the device body 2 by a distance X1 in the longitudinal direction LD than the left first surface 81Lf, 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 composed of surfaces parallel to the mounting direction AD (Y direction) and the Z direction, but is not limited to this. 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 has a left positioning portion 81L into which the left positioning boss 21L can engage, and the left positioning portion 81L, as the first positioning portion, is a notch that is open on the upstream side in the mounting direction AD. The left second surface 82Lf has a left rotation restricting portion 82L into 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 that is open on the upstream side in the mounting direction AD. Note that since the left second surface 82Lf is formed by drawing, it may have a slope that guides the left positioning boss 21L toward the left positioning portion 81L.

[0036] Furthermore, since the left first surface 81Lf and the left second surface 82Lf are located at a distance of X1 in the longitudinal direction LD, the left rotation restricting section 82L is also positioned at a distance of X1 in the longitudinal direction LD relative to the left positioning section 81L. In other words, the left rotation restricting section 82L is positioned at a different location from the left positioning section 81L in the longitudinal direction LD.

[0037] Similarly, as shown in Figures 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 mounting direction AD (Y direction) and the Z direction. The right second surface 82Rf is positioned further inward from the device body 2 in the longitudinal direction LD by a distance X2 from the right first surface 81Rf, 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 composed of surfaces parallel to the mounting direction AD (Y direction) and the Z direction, but are not limited to this. 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 has a right positioning portion 81R into 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 mounting direction AD. The right second surface 82Rf has a right rotation restricting portion 82R into 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 mounting direction AD. Note that since the right second surface 82Rf is formed by drawing, a slope may be formed to guide the right positioning boss 21R toward the right positioning portion 81R.

[0039] Furthermore, since the right first surface 81Rf and the right second surface 82Rf are located at a distance of X2 in the longitudinal direction LD, the right rotation restricting section 82R is also positioned at a distance of X2 in the longitudinal direction LD relative to the right positioning section 81R. In other words, the right rotation restricting section 82R is positioned at a different location from the right positioning section 81R in the longitudinal direction LD.

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

[0041] The process unit 20 is positioned in the mounting direction AD by the engagement of the left positioning boss 21L and the right positioning boss 21R with the left positioning section 81L and the right positioning section 81R, respectively. Furthermore, the rotational movement of the process unit 20 around the left positioning boss 21L and the right positioning boss 21R is restricted by the engagement of the left rotation restricting boss 22L and the right rotation restricting boss 22R with the left rotation restricting section 82L and the right rotation restricting section 82R, respectively. In other words, the process unit 20 is positioned in the Z direction, which is the first direction.

[0042] More specifically, as shown in Figure 6(b), the left positioning section 81L has protrusions 51, 52, and 53 that the left positioning boss 21L abuts against. When the process unit 20 is mounted on the apparatus body 2, the left positioning boss 21L abuts against the protrusions 51 and 52 in the mounting direction AD and is positioned. 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 section 81L, together with the left rotation restricting section 82L, positions the process unit 20 in the Z direction.

[0043] Furthermore, when the process unit 20 is mounted on the main body 2, that is, 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 mounting direction AD relative to the left rotation restricting section 82L. In other words, the left rotation restricting section 82L 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 section 81L. As a result, the process unit 20 is reliably positioned in the mounting direction AD by the left positioning section 81L, and the positioning accuracy of the process unit 20 can be improved.

[0044] Note that the right positioning unit 81R and the right rotation restricting unit 82R have the same configuration as the left positioning unit 81L and the left rotation restricting unit 82L, so their explanation will be omitted.

[0045] Figure 6(c) is an enlarged view showing a modified version of the first embodiment, specifically the left positioning section 281L and the left rotation restricting section 282L. In the embodiment shown in Figure 6(b), the left positioning section 81L was positioned upstream of the left rotation restricting section 82L in the mounting direction AD, but is not limited to this. For example, as shown in Figure 6(c), the left positioning section 281L, as the first positioning section, may be positioned downstream of the left rotation restricting section 282L, as the second positioning section, in the mounting direction AD.

[0046] The left positioning portion 281L has surfaces 251, 252, and 253, with surfaces 251 and 253 facing each other in the Z direction. When the process unit 20 is mounted on the apparatus body 2, the left positioning boss 221L, as the first positioned portion, abuts against surface 252 of the left positioning portion 281L and is positioned in the mounting direction AD. At this time, the left positioning boss 221L also abuts against surfaces 251 and 253 in the Z direction, and is therefore positioned in the Z direction as well.

[0047] The left rotation restricting section 282L has protrusions 261 and 262. The left rotation restricting boss 222L, which is the second positioning section, is positioned in the Z direction by contacting the protrusions 261 and 262 when the process unit 20 is positioned in the mounting direction AD by the left positioning section 81L. 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 section 282L. In other words, the left rotation restricting section 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 section 281L. As a result, the process unit 20 is reliably positioned in the mounting direction AD by the left positioning section 281L, and the positioning accuracy of the process unit 20 can be improved.

[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 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 plate frame 74.

[0049] As shown in Figure 7(a), the left second surface 82Lf, where the left rotation restricting portion 82L is formed, is located inside the device body 2 in the longitudinal direction LD relative to the left first surface 81Lf, where the left positioning portion 81L is formed. Similarly, the left rotation restricting boss 22L is also located inside the device body 2 in the longitudinal direction LD relative to the left positioning boss 21L. As a result, the notch shape forming the left rotation restricting portion 82L on the left second surface 82Lf requires a relatively small area. Furthermore, since the left positioning portion 81L is located upstream of the left rotation restricting portion 82L in the mounting direction AD, the notch shape forming the left positioning portion 81L on the left first surface 81Lf also requires a relatively small area. In this way, by reducing the area of ​​the notches formed on the left side plate frame 73, the rigidity of the left side plate frame 73 can be maintained.

[0050] Similarly, as shown in Figure 7(b), the right second surface 82Rf, where the right rotation restricting portion 82R is formed, is located inside the device body 2 in the longitudinal direction LD relative to the right first surface 81Rf, where the right positioning portion 81R is formed. The right rotation restricting boss 22R is also located inside the device body 2 in the longitudinal direction LD relative to the left positioning boss 21R. As a result, the notch shape that constitutes the right rotation restricting portion 82R formed on the right second surface 82Rf requires a relatively small area. Furthermore, since the right positioning portion 81R is located upstream of the right rotation restricting portion 82R in the mounting direction AD, the notch shape that constitutes 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 notches formed on the right side plate frame 74, the rigidity of the right side plate frame 74 can be maintained.

[0051] By maintaining the rigidity of the left-side plate frame 73 and the right-side plate frame 74, the positioning accuracy of the process unit 20 relative to the apparatus body 2 can be improved. Furthermore, since it is not necessary to make the left-side plate frame 73 and the right-side plate frame 74 thicker in order to increase their rigidity, weight reduction and cost reduction can be achieved.

[0052] Figure 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 Figure 8, the left positioning section 81L has two faces 81La and 81Lc that face each other in the Z direction, and a surface 81Lb that connects these two faces 81La and 81Lc and faces the left positioning boss 21L in the mounting direction AD. The left rotation restricting section 82L also has two faces 82La and 82Lb that face each other in the Z direction.

[0053] The width of the left positioning section 81L in the Z direction, i.e., the distance between surfaces 81La and 81Lc, is width Z1. The width of the left rotation restricting section 82L in the Z direction, i.e., the distance between surfaces 82La and 82Lb, is width Z2. The left rotation restricting section 82L is positioned so that at least a portion of it overlaps with the left positioning section 81L in the Z direction. As a result, when the process unit 20 is mounted on the apparatus body 2, the movement trajectories of the left positioning boss 21L and the left rotation restricting boss 22L in the Z direction overlap, and the area within the apparatus body 2 that needs to be avoided by this movement trajectory can be suppressed. Therefore, the space within the apparatus body 2 can be used effectively, and the image forming apparatus 1 can be miniaturized.

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

[0055] Furthermore, the above-described configuration shown in Figure 8 is the same on the right-side plate frame 74 side and produces the same effect. In addition, in this embodiment, the axis 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. The second embodiment is a modification of the configuration of the left second surface 82Lf and the right second surface 82Rf of the first embodiment. For this reason, the same configuration as in the first embodiment will be omitted from the illustration or will be described using the same reference numerals in the illustration.

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

[0058] As shown in Figure 9, the process unit 20B has a left side 30L and a right side 30R as end faces in the longitudinal direction LD, and two downstream faces 31L and 31R in the mounting direction AD. A left rotation restricting boss 22BL is provided on face 31L as a second positioning portion, and a right rotation restricting boss 22BR is provided on face 31R. The left rotation restricting boss 22BL and the right rotation restricting boss 22BR extend downstream in the mounting direction AD. The left positioning boss 21BL and the right positioning boss 21BR are positioned upstream of the left rotation restricting boss 22BL and the right rotation restricting boss 22BR, respectively, in the mounting direction AD.

[0059] The main 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 Figures 9 and 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 positioned inward of the device body 2 in the longitudinal direction LD compared to 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 composed of surfaces 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 has a left rotation restricting portion 82BL that can engage with the left rotation restricting boss 22BL, and the left rotation restricting portion 82BL, which serves as the second positioning portion, is composed of a hole that penetrates 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 located inside the device body 2 in the longitudinal direction LD compared to the left first surface 81Lf, the left rotation restricting portion 82BL is located in a different position from the left positioning portion 81BL in the longitudinal direction LD.

[0062] Similarly, as shown in Figures 9 and 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 positioned further inside the device body 2 in the longitudinal direction LD than the right first surface 81Rf 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 composed of surfaces parallel to the mounting direction AD (Y direction) and the Z direction, but are not limited to this. 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 has a right rotation restricting portion 82BR that can engage with the right rotation restricting boss 22BR, and the right rotation restricting portion 82BR is composed of a hole that penetrates in the mounting 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. Since the right second surface 82BRf is located inside the device body 2 in the longitudinal direction LD compared to the right first surface 81Rf, the right rotation restricting portion 82BR is located in a different position from the right positioning portion 81BR in the longitudinal direction LD.

[0064] Figures 10(a) to 11 are perspective views showing the image forming apparatus 1B with the process unit 20B installed. As shown in Figure 11, when the process unit 20B is installed on the apparatus body 2B, the process unit 20B is biased from the rear side to the front side by a biasing mechanism (not shown). When the process unit 20B is installed on the apparatus 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 installed on the apparatus 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 section 81L and the right positioning section 81R, respectively. Furthermore, the rotational movement of the process unit 20B around the left positioning boss 21L and the right positioning boss 21R is restricted by the left rotation restricting boss 22BL and the right rotation restricting boss 22BR engaging with the right rotation restricting section 82BR and the right rotation restricting section 82BR, respectively. In other words, the process unit 20B is positioned in the Z direction.

[0066] Similar to the first embodiment, the left second surface 82BLf, on which the left rotation restricting portion 82BL is formed, is located inside the device body 2 in the longitudinal direction LD relative to the left first surface 81Lf, on which the left positioning portion 81L is formed. Similarly, the left rotation restricting boss 22BL is also located inside the device body 2 in the longitudinal direction LD relative to the left positioning boss 21L. As a result, the hole shape that constitutes the left rotation restricting portion 82BL formed on the left second surface 82BLf requires a relatively small area. Furthermore, since the left positioning portion 81L is located upstream of the left rotation restricting portion 82BL in the mounting direction AD, the notch shape that constitutes 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 ​​notches and holes formed on the left side plate frame 73B as a frame member, the rigidity of the left side plate frame 73B can be maintained.

[0067] Similarly, the rigidity of the right-side plate frame 74B can be maintained by reducing the area of ​​the notches and holes formed in the right-side plate frame 74B. Maintaining the rigidity of the left-side plate frame 73B and the right-side plate frame 74B improves the positioning accuracy of the process unit 20B relative to the apparatus body 2B. Furthermore, since it is not necessary to make the left-side plate frame 73B and the right-side plate frame 74B thicker in order to increase their rigidity, weight reduction and cost reduction can be achieved.

[0068] <Third Embodiment> Next, a third embodiment of the present invention will be described. In the third embodiment, the fixing unit 9 is configured to be detachably attached to the apparatus body 2C, rather than the process unit 20 of the first embodiment. For this reason, the same configuration as in the first embodiment will be omitted from the illustration or will be described using the same reference numerals in the illustration.

[0069] Figure 12 is a perspective view showing the image forming apparatus 1C according to the third embodiment before the attachment unit and the fixing unit 9, which serves as the fixing part, are attached. As shown in Figure 12, the fixing unit 9 has a left side surface 41L and a right side surface 41R as end faces in the longitudinal direction LD parallel to the X direction. The left side surface 41L is provided with a left positioning boss 21L and a left rotation restricting boss 22L, and similarly the right side surface 41R is provided with a right positioning boss 21R and a right rotation restricting boss 22R (see Figure 7(b)).

[0070] Figure 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 Figure 13, when the fixing unit 9 is mounted on the device body 2, the fixing unit 9 is biased from the rear side to the front side by a biasing mechanism (not shown). When the fixing unit 9 is mounted on 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 mounted on 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 section 81L and the right positioning section 81R, respectively. Furthermore, the rotational movement of the fixing unit 9 around the left positioning boss 21L and the right positioning boss 21R is restricted by the left rotation restricting boss 22L and the right rotation restricting boss 22R engaging with the left rotation restricting section 82L and the right rotation restricting section 82R, respectively. In other words, the fixing unit 9 is positioned in the Z direction.

[0072] The left positioning boss 21L, the left rotation restricting boss 22L, the right positioning boss 21R, and the right rotation restricting boss 22R have the same configuration as in the first embodiment, so their description is omitted. In this embodiment as well, the same effects as in the first embodiment are achieved.

[0073] <Other Embodiments> In all of the configurations described above, the process units 20, 20B and the fixing unit 9 are mounted from the rear side to the front side of the apparatus body 2, 2B, 2C, but this is not limited to this configuration. In other words, the mounting direction AD does not have to be in the direction along the Y direction.

[0074] Furthermore, in all of the embodiments described above, the process units 20, 20B and the fixing unit 9 are provided with boss-shaped positioning bosses and rotation-restricting bosses, but the invention is not limited to these. That is, the process units 20, 20B and the fixing unit 9 may also be provided with positioning parts and rotation-restricting parts that are not boss-shaped.

[0075] Furthermore, in the first and second embodiments, process units 20 and 20B having a photosensitive drum 11, a developing roller 12, and a storage section 18 are configured to be detachably attached to the main body 2 and 2B of the device, but the invention is not limited thereto. For example, instead of a process unit, only a storage section 18 for storing toner may be used, or a developing unit having a developing roller 12 and a storage section 18 but without a photosensitive drum 11 may be used. The device may be configured to be positionable on the main body 2 by the positioning configuration described above.

[0076] Furthermore, in all of the above-described configurations, the left positioning section 81L was positioned upstream of the left rotation restricting sections 82L and 82BL in the mounting direction AD, but this is not limited to this configuration. For example, the left positioning section 81L may be positioned downstream of the left rotation restricting sections 82L and 82BL in the mounting direction AD. In this case, it is preferable that the left positioning section 81L be provided on the left second surface 82Lf and 82BLf, and the left rotation restricting section 82L be provided on the left first surface 81Lf.

[0077] Furthermore, although the above-described embodiments have been explained using electrophotographic image forming apparatuses 1, 1B, and 1C, the present invention is not limited thereto. For example, the present invention can also be applied to inkjet image forming apparatuses that form images 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, fuser unit (fussing unit) / 18: Toner storage unit (storage unit) / 20,20B: Detachable unit (process unit) / 21L,221L: First positioning unit (left positioning boss) / 22L,22BL,222L: Second positioning unit (left rotation restricting boss) / 30L: End face (left side) / 31L: Face / 41L :End face (left side) / 73,73B:Frame member (left plate frame) / 81L,281L:First positioning part (left positioning part) / 81Lf:First surface (left first surface) / 82L,82BL,282L:Second positioning part (left rotation restricting part) / 82Lf,82BLf:Second surface (left second surface) / 200:Inlet (supply port) / AD:Mounting direction / LD:Second direction (longitudinal direction) / Z:First direction (direction)

Claims

1. In an image forming apparatus that forms an image on a sheet, A unit comprising: a photosensitive drum rotatable about a rotation axis extending in a direction intersecting the direction of gravity; a developing roller supplying toner to the photosensitive drum; and a first projection and a second projection projecting from the end face of the unit in the direction of the rotation axis; The device comprises a main body to which the aforementioned unit is detachably attached, The first protrusion has a first contact portion including a first contact surface, The second protrusion has a second contact portion including a second contact surface, The tip of the second projection is located further inside the unit than the tip of the first projection in the direction of the rotation axis. The unit is configured to be mounted to the device body from a first position in which a part of the unit is located outside the device body, along a mounting direction that intersects both the rotation axis direction and the gravity direction, to a second position in which the unit is located inside the device body and is positioned relative to the device body in the mounting direction. The device body has a side plate portion provided opposite the end face 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 contact portion has a first contact surface that contacts the first contact surface of the first contact portion of the unit when the unit is in the second position. The second contact portion has a second contact surface that contacts the second contact surface of the second contact portion of the unit when the unit is in the second position. The second contact surface is positioned downstream of the first contact surface in the mounting direction and inside the device body relative to the first contact surface in the rotation axis direction. The second contact surface is positioned downstream of the first contact surface in the mounting direction and further inside the unit than the first contact surface in the rotation axis direction. An image forming apparatus characterized by the following features.

2. The side plate portion has a sheet metal member including a constricted portion that is retracted inward in the direction of the rotation axis, such that the second contact surface is located inward of the device body than the first contact surface in the direction of the rotation axis. The image forming apparatus according to feature 1.

3. The sheet metal member has a first notch and a second notch, The first contact portion is exposed from the sheet metal member through the first notch portion, The second contact portion is exposed from the sheet metal member through the second notch. The image forming apparatus according to feature 2.

4. It further includes a fixing unit that fixes the image on the sheet to the sheet, The first contact portion and the second contact portion are located below the fixing portion. The image forming apparatus according to any one of claims 1 to 3.

Images