Image forming device

Abstract

To provide an image forming apparatus that can reduce operating force to open an opening and closing part to improve usability.SOLUTION: An image forming apparatus comprises: an apparatus body that has a rotatable image carrier; an opening and closing part that is provided between a first closed position and a first open position in an openable and closable manner; an urging part that urges the opening and closing part toward the first closed position; a lock part that is movable to a lock position and an unlock position; and a cover part that is provided between a second closed position and a second open position in an openable and closable manner, and at the second closed position, covers the opening and closing part located at the first closed position. When the cover part is located at the second closed position, the lock part is located at the lock position. The urging force of the urging part is larger than first reactive force that the opening and closing part receives from the apparatus body, and is smaller than a total sum of the first reactive force and second reactive force that the opening and closing part receives from a recording material conveyed on a conveyance path.SELECTED DRAWING: Figure 35

Description

[Technical Field]

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

[0002] Generally, electrophotographic image forming apparatuses form images by transferring a toner image formed on the surface of a photosensitive drum onto a recording medium. Developer replenishment methods include a process cartridge replacement method and a toner replenishment method. The process cartridge replacement method involves replacing the process cartridge with a new one when the developer runs out. The toner replenishment method involves replenishing new toner into a developing container when the toner runs out.

[0003] Patent Document 1 proposes an image forming apparatus equipped with a duplex unit and a secondary transfer unit that can be opened and closed. In the event of a jam near the secondary transfer roller, this image forming apparatus allows access to the jammed recording medium by first opening the duplex unit and then the secondary transfer unit. The secondary transfer unit is also provided with a secondary transfer lock mechanism that can lock the secondary transfer unit in a closed position by engaging with a main body-side engaging portion provided on the apparatus main body. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-021918 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in order to form a secondary transfer nip that transfers a toner image to a recording medium even when pressed by the recording medium being conveyed, the secondary transfer unit may be biased toward the closed position by a biasing member. However, if the biasing force of the biasing member is increased, the operating force required by the user to open the secondary transfer unit increases, reducing usability.

[0006] SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus that can reduce the operating force required to open an opening / closing section and improve usability. [Means for solving the problem]

[0007] The present invention provides An image can be formed on a recording material having a basis weight equal to or greater than a predetermined value. Image forming device And a transfer nip formed between the image carrier and the main body of the image forming apparatus, and a transfer nip formed between the image carrier and the main body of the image forming apparatus; The aforementioned a transfer member for transferring the image onto a recording material; The aforementioned a transfer nip provided adjacent to the transfer nip at a position upstream of the transfer nip in the recording material conveyance direction; The aforementioned the opening / closing unit is provided so as to be able to open and close between a first closed position where the opening / closing unit is closed with respect to the device body and a first open position where the opening / closing unit is open with respect to the device body; a biasing unit which biases the opening / closing unit toward the first closed position; a locking unit which is provided on either the opening / closing unit or the device body and is movable between a locked position where the opening / closing unit located at the first closed position is locked with respect to the device body and an unlocked position where the opening / closing unit is unlocked with respect to the device body; and a cover which is provided so as to be able to open and close between a second closed position where the opening / closing unit is closed with respect to the device body and a second open position where the opening / closing unit is open with respect to the device body and covers the opening / closing unit located at the first closed position when at the second closed position, The aforementioned When the locking position is set to the second closed position, death , the biasing force of the biasing portion is greater than a first reaction force that the opening / closing portion receives from the apparatus main body, and is smaller than a sum of a second reaction force that the opening / closing portion receives from the recording material being transported in the transport direction and the first reaction force. It is characterized by: [Effects of the Invention]

[0008] According to the present invention, the operating force required to open the opening / closing section can be reduced, thereby improving usability. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic view showing an entire image forming apparatus. [Figure 2] FIG. 1 is a cross-sectional view showing a configuration of an image forming apparatus. [Figure 3] FIG. 1 is a perspective view showing an internal configuration of an image forming apparatus. [Figure 4] FIG. 3 is a block diagram illustrating the function of a power supply board. [Figure 5] FIG. 2 is a perspective view showing the image forming apparatus before a process unit is attached. [Figure 6] 1A is a rear view and an enlarged view showing the positioning configuration of the process unit by the left plate frame, and FIG. 1B is a rear view and an enlarged view showing the positioning configuration of the process unit by the right plate frame. [Figure 7] FIG. 2 is a perspective view showing the image forming apparatus with a process unit attached thereto. [Figure 8] FIG. [Figure 9] FIG. [Figure 10] (a) is a perspective view showing an image forming apparatus with the discharge tray closed, (b) is a perspective view showing an image forming apparatus with the discharge tray open, and (c) is a perspective view showing an image forming apparatus with a supply pack attached to the supply section. [Figure 11] 1A is a perspective view showing the supply unit, FIG. 1B is a perspective view showing the supply unit and a part of the supply pack, and FIG. 1C is a perspective view showing the supply unit when the operating unit is located at the supply position. [Figure 12] FIG. 2 is a left side view showing the image forming apparatus. [Figure 13] FIG. 1 is a plan view showing an image forming apparatus. [Figure 14] 1A is a perspective view showing the supply pack when the pack shutter is in the closed position, and FIG. 1B is another perspective view showing the supply pack when the pack shutter is in the closed position. [Figure 15] 1A is a perspective view showing the supply pack when the pack shutter is in the open position, and FIG. 1B is another perspective view showing the supply pack when the pack shutter is in the open position. [Figure 16] FIG. 2A is an exploded perspective view showing the supply pack, and FIG. 2B is another exploded perspective view showing the supply pack. [Figure 17] (a) is a perspective view showing an image forming apparatus with the rear cover closed, (b) is a perspective view showing an image forming apparatus with the rear cover open, and (c) is a perspective view showing an image forming apparatus with the transfer unit open. [Figure 18] (a) is a cross-sectional view showing the image forming apparatus with the rear cover closed, (b) is a cross-sectional view showing the image forming apparatus with the rear cover open, (c) is a cross-sectional view showing the image forming apparatus with the transfer unit open, and (d) is a cross-sectional view showing the image forming apparatus in the process of closing the rear cover. [Figure 19] (a) is a perspective view showing the image forming apparatus with the rear cover closed, (b) is a perspective view showing the image forming apparatus with the transfer unit open, (c) is a perspective view showing the start of removal of the process unit, and (d) is a perspective view showing the removal process of the process unit. [Figure 20] (a) is a cross-sectional view showing the image forming apparatus with the rear cover closed, (b) is a cross-sectional view showing the image forming apparatus with the transfer unit open, (c) is a cross-sectional view showing the start of removal of the process unit, and (d) is a cross-sectional view showing the removal process of the process unit. [Figure 21] FIG. 2 is a perspective view showing the image forming apparatus with the rear cover open. [Figure 22] (a) is a perspective view showing the link and its surrounding structure when the transfer unit is in the closed position, (b) is a side view showing the link and its surrounding structure, (c) is a perspective view showing the link, link holder, and tension spring, and (d) is another perspective view showing the link, link holder, and tension spring. [Figure 23](a) is a perspective view showing the link and its surrounding structure when the transfer unit is in the open position, (b) is a side view showing the link and its surrounding structure, (c) is a perspective view showing the link, link holder, and tension spring, and (d) is another perspective view showing the link, link holder, and tension spring. [Figure 24] FIG. 10A is a side view showing the link when the transfer unit is in the open position, and FIG. 10B is a side view showing the link when the transfer unit is slightly lifted from the open position. [Figure 25] 1A is a side view showing the link when the transfer unit is on its way to the closed position, and FIG. 1B is a side view showing the link when the transfer unit is on its way to the closed position. [Figure 26] 1A is a side view showing the link when the transfer unit is on its way to the closed position, and FIG. 1B is a side view showing the link when the transfer unit is on its way to the closed position. [Figure 27] 1A is a side view showing the link when the transfer unit is on its way to the closed position, and FIG. 1B is a side view showing the link when the transfer unit is located at the closed position. [Figure 28] FIG. 10A is a side view showing the link when the transfer unit is in the closed position, and FIG. 10B is a side view showing the link when the transfer unit is slightly opened from the closed position. [Figure 29] 1A is a perspective view showing the locking member 99R as viewed from the minus Y direction, (b) is another perspective view showing the locking member 99R as viewed from the minus Y direction, (c) is a perspective view showing the locking member 99R removed from the transfer unit 7, and (d) is another perspective view showing the locking member 99R removed from the transfer unit 7. [Figure 30] View of the device body from the minus Y direction. [Figure 31] 31A is a cross-sectional view taken along line 31AB-31AB in FIG. 30 showing the image forming apparatus when the locking member is positioned at the unlocked position, and FIG. 31B is a cross-sectional view taken along line 31AB-31AB in FIG. 30 showing the locking member positioned at the unlocked position. [Figure 32]32A is a cross-sectional view taken along line 32AB-32AB in FIG. 30 showing the image forming apparatus when the locking member is in the locked position, and FIG. 32B is a cross-sectional view taken along line 32AB-32AB in FIG. 30 showing the locking member in the unlocked position. [Figure 33] FIG. [Figure 34] 1A is a cross-sectional view showing the locking member when the rear cover is closed, and FIG. 1B is a cross-sectional view showing the locking member being rotated toward the unlocked position by an unlocking claw. [Figure 35] FIG. 6 is a cross-sectional view showing a reaction force acting on the transfer unit. [Figure 36] FIG. 10 is a schematic overall view showing an image forming apparatus according to a second embodiment. [Figure 37] 10 is a schematic diagram showing a state in which the locking member is rotated from the locked position to the unlocked position by the unlocking claw. FIG. [Figure 38] FIG. 2 is a schematic diagram showing the image forming apparatus when the cover member is in the open position. [Figure 39] FIG. 2 is a schematic diagram showing the image forming apparatus when the cover member and the opening / closing member are in the open position. DETAILED DESCRIPTION OF THE INVENTION

[0010] The following describes in detail exemplary embodiments of the present invention with reference to the drawings. However, the dimensions, materials, shapes, and relative positions of the components described in the embodiments may be changed as appropriate depending on the configuration of the device to which the invention is applied and various conditions. In other words, the scope of the present invention is not limited to the following embodiments.

[0011] First Embodiment Fig. 1 is a perspective view showing an image forming apparatus 1 according to a first embodiment. Fig. 2 is a cross-sectional view showing the configuration of the image forming apparatus 1. The image forming apparatus 1 is a monochrome printer that forms an image on a recording material based on image information input from an external device. The recording material includes various sheet materials of different materials, such as paper such as plain paper and cardboard, plastic film such as sheets for overhead projectors, sheets of special shapes such as envelopes and index paper, and cloth.

[0012] In the following description, the height direction of the image forming apparatus 1 (the direction opposite to the vertical direction) when the image forming apparatus 1 is installed on a horizontal surface is referred to as the Z direction. The direction that intersects with the Z direction and is parallel to the direction of the rotation axis of the photosensitive drum 11 (main scanning direction) described later is referred to as the X direction. The direction that intersects with the X and Z directions is referred to as the Y direction. The X, Y, and Z directions preferably intersect perpendicularly with each other. For convenience, the positive side in the X direction is referred to as the right side and the negative side is referred to as the left side; the positive side in the Y direction is referred to as the front side or front side and the negative side is referred to as the rear side or back side; and the positive side in the Z direction is referred to as the upper side and the negative side is referred to as the lower side.

[0013] [Overall configuration] As shown in Figures 1 and 2, the image forming apparatus 1 has an image forming section 20 that forms a toner image on a recording material, a feeding section 30 that feeds the recording material P, a fixing section 9 that fixes the toner image formed by the image forming section 20 to the recording material, and a pair of discharge rollers 10.

[0014] The image forming section 20 has a scanner unit 50, an electrophotographic process unit 40, and a transfer unit 7 including a transfer roller 7a that transfers a toner image carried on a photosensitive drum 11 of the process unit 40 onto a recording material P. The process unit 40 has the photosensitive drum 11, a cleaning unit 13 arranged around the photosensitive drum 11, a charging roller 17, a developing roller 12, a supply section 200 (see FIG. 3), and a developer container 230 (see FIG. 8) equipped with a storage section 18 that stores toner. The transfer roller 7a is urged toward the photosensitive drum 11 by a urging member (not shown).

[0015] The photosensitive drum 11 serving as an image carrier is a cylindrically shaped photosensitive member. The photosensitive drum 11 of this embodiment has a photosensitive layer formed of a negatively chargeable organic photosensitive material on a drum-shaped substrate made of aluminum. The photosensitive drum 11 is driven to rotate in a predetermined direction (direction R in the figure) at a predetermined process speed by a motor.

[0016] The charging roller 17 contacts the photosensitive drum 11 with a predetermined pressure to form a charging portion. A desired charging voltage is applied from a charging high-voltage power supply, thereby uniformly charging the surface of the photosensitive drum 11 to a predetermined potential. In this embodiment, the photosensitive drum 11 is negatively charged by the charging roller 17.

[0017] The scanner unit 50 uses a polygon mirror to irradiate the photosensitive drum 11 with laser light corresponding to image information input from an external device, thereby scanning and exposing the surface of the photosensitive drum 11. This exposure forms an electrostatic latent image corresponding to the image information on the surface of the photosensitive drum 11. Note that the scanner unit 50 is not limited to a laser scanner device, and may, for example, be an LED exposure device having an LED array in which a plurality of LEDs are arranged along the longitudinal direction of the photosensitive drum 11.

[0018] 3 and 5, the apparatus main body 2 of the image forming apparatus 1 has a left side panel frame 74 and a right side panel frame 75, and a scanner holding member 76 is suspended between the left side panel frame 74 and the right side panel frame 75. The scanner holding member 76 holds the scanner unit 50. Meanwhile, a drive motor 311 serving as a drive source is attached to the right side panel frame 75, and a pinion gear connected to the drive motor 311 is provided on the positive side (right side) of the right side panel frame 75 in the X direction. The driving force of the drive motor 311 is transmitted to the feed roller 5a and the photosensitive drum 11 via this pinion gear.

[0019] 1 and 2, the developing roller 12 is rotatably supported by a storage portion 18 serving as a toner storage portion. The developing roller 12 is disposed at the opening of a developer container 230 (see FIG. 8) including the storage portion 18 so as to face the photosensitive drum 11. The storage portion 18 may be provided with a supply roller that applies toner stored in the storage portion 18 as a developer onto the surface of the developing roller 12.

[0020] The process unit 40 of this embodiment uses a contact development method. That is, a toner layer carried on 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 on the development roller 12 is transferred from the development roller 12 to the drum surface in accordance with the potential distribution on the surface of the photosensitive drum 11, thereby developing the electrostatic latent image into a toner image.

[0021] The toner of this embodiment does not contain a magnetic component, and is a so-called non-magnetic one-component developer in which the toner is carried on the developing roller 12 mainly by intermolecular forces and electrostatic forces (image forces). However, a one-component developer containing a magnetic component may also be used. In addition to toner particles, a one-component developer may also contain additives (e.g., wax or silica particles) for adjusting the fluidity and charging performance of the toner. A two-component developer composed of non-magnetic toner and a magnetic carrier may also be used as the developer. When a magnetic developer is used, a cylindrical developing sleeve with a magnet disposed inside is used as the developer carrier, for example.

[0022] The fixing unit 9 is a thermal fixing type that fixes an image by heating and melting the toner on the recording material. The fixing unit 9 includes a heating film 9a that incorporates a fixing heater 9c, and a pressure roller 9b that presses against the heating film 9a.

[0023] 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 front end surface of the image forming apparatus 1, and the front cover 70 covers a circuit board 100. The apparatus main body 2 of the image forming apparatus 1 has a housing 72. The housing 72 has the front cover 70 of the apparatus main body 2, a discharge tray 14, and an exterior cover 71 that forms the exterior of the image forming apparatus 1, and supports a rear cover 73 (see FIG. 17(a)) in an openable and closable manner. The housing 72 is formed with a discharge opening 15 through which the recording material P passes before being discharged to the discharge tray 14.

[0024] As shown in FIG. 2, the image forming apparatus 1 has a circuit board 100. The circuit board 100 is composed of a wiring board 101 made of an insulator and electronic components 111 and 121 soldered to the wiring board 101. Conductor wiring is provided on and inside the wiring board 101, so that the electronic components 111 and 121 are electrically connected. The circuit board 100 has the function of converting AC current supplied from outside the image forming apparatus 1 into DC current, and converting the input voltage to obtain a predetermined voltage value required for the image formation process.

[0025] 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.

[0026] Next, an image forming operation of the image forming apparatus 1 will be described. When an image formation command is input to the image forming apparatus 1, the image forming process is started by the image forming section 20 based on image information input from an external computer connected to the image forming apparatus 1. The scanner unit 50 irradiates the photosensitive drum 11 with laser light based on the input image information. At this time, the photosensitive drum 11 is pre-charged by the charging roller 17, and an electrostatic latent image is formed on the photosensitive drum 11 by the irradiation of the laser light. Thereafter, the electrostatic latent image is developed by the developing roller 12, and a toner image is formed on the photosensitive drum 11.

[0027] In parallel with the image forming process described above, a pickup roller 3 of a feeding unit 30 feeds a recording material P supported by a cassette 4. The recording material P fed by the pickup roller 3 is separated into individual sheets by a feeding roller 5a and a separation roller 5b, and is conveyed to a conveying roller pair 5c. The recording material P is then conveyed by the conveying roller pair 5c as a conveying unit toward a transfer nip N1 as an image forming unit formed by a transfer roller 7a and a photosensitive drum 11.

[0028] A transfer voltage is applied to the transfer roller 7a, which serves as a transfer member, from a transfer high-voltage power supply, and the toner image carried on the photosensitive drum 11 is transferred onto the recording material P being conveyed by the conveying roller pair 5c. The recording material P with the transferred toner image is conveyed to the fixing unit 9, and the toner image is heated and pressurized as it passes through the fixing nip N2 between the heating film 9a and pressure roller 9b of the fixing unit 9. This melts the toner particles and then solidifies them, thereby fixing the toner image to the recording material P. After passing through the fixing unit 9, the recording material P is discharged from the discharge port 15 by the discharge roller pair 10 to the outside of the image forming apparatus 1 (outside the machine) and is stacked on the discharge tray 14.

[0029] When forming images on both sides of the recording material P, the pair of discharge rollers 10 switches back the recording material P with the image formed on its first side, guiding the recording material P to the double-sided conveying path 16. The recording material P guided to the double-sided conveying path 16 is again conveyed by the pair of double-sided conveying rollers 5d via the conveying path 19 toward the transfer roller 7a. After the image is formed on the second side of the recording material P by the transfer roller 7a, the recording material P is discharged to the outside of the apparatus by the pair of discharge rollers 10. After the toner image is transferred to the recording material P, any toner remaining on the photosensitive drum 11 is cleaned by the cleaning unit 13. Note that the image forming apparatus 1 of this embodiment is configured to be able to form images on both sides of the recording material P using the double-sided conveying path 16, but is not limited to this. For example, the image forming apparatus 1 may be configured to be able to form an image on only one side of the recording material P without the double-sided conveying path 16.

[0030] [Control Block] FIG. 4 is a block diagram illustrating the function of circuit board 100 according to this embodiment. Circuit board 100 includes low-voltage power supply unit 110 and high-voltage power supply unit 120. Low-voltage power supply unit 110 receives power from an external power source via a power supply input unit (not shown) mounted on the edge of the board and converts the AC voltage into a stable DC voltage using a rectifying and smoothing circuit including an electrolytic capacitor. Low-voltage power supply unit 110 then converts the DC voltage into a high-frequency AC voltage using switching elements such as transistors, and inputs the high-frequency AC voltage into a low-voltage power transformer. The low-voltage power transformer converts the high-frequency AC voltage, which is the input voltage, into an AC voltage (output voltage) having a desired voltage value. Low-voltage power supply unit 110 again converts the AC voltage into a DC voltage and outputs the resulting DC voltage to high-voltage power supply unit 120. Because losses in individual circuit components manifest as heat, low-voltage power supply unit 110 is provided with a heat sink (not shown) made of aluminum or iron for heat dissipation.

[0031] The high-voltage power supply unit 120 converts the voltage (for example, 24 V) supplied from the low-voltage power supply unit 110 into a high voltage required for the image formation process, such as charging, developing, and transferring. The voltage supplied from the low-voltage power supply unit 110 is converted into a charging voltage by a charging transformer and supplied to the charging roller 17. The voltage supplied from the low-voltage power supply unit 110 is converted into a developing voltage by a developing transformer 123 and supplied to the developing roller 12. The voltage supplied from the low-voltage power supply unit 110 is converted into a transferring voltage by a transferring transformer and supplied to the transfer roller 7a.

[0032] The low-voltage power supply unit 110 supplies voltage (e.g., 3.3 V or 5 V) not only to the high-voltage power supply unit 120 but also to the scanner unit 50, the drive motor 311, the engine controller 130, and the video controller 140. The engine controller 130 is responsible for overall control of the various process components. The engine controller 130 includes a CPU (not shown), a RAM (not shown) used for calculations and temporary storage of data required to control the image forming apparatus 1, and a ROM (not shown) for storing programs and various data for controlling the image forming apparatus 1. The video controller 140 communicates with an external device such as a personal computer to receive print data and notifies the engine controller 130 of the results of analyzing the print data. The engine controller 130 and the video controller 140 may be provided on a board separate from the circuit board 100, or may be provided on the same board.

[0033] Furthermore, AC power received by the power input unit from the commercial power supply is supplied not only to the low-voltage power supply unit 110 but also to the fixing heater 9c. The rollers and other components in the fixing unit 9 are driven by a drive motor 311.

[0034] [Process unit positioning configuration] Next, the positioning configuration of the process unit 40 will be described with reference to Figures 5 to 7. Figure 5 is a perspective view showing the image forming apparatus 1 in a state before the process unit 40 is installed. Figure 6(a) is a rear view and an enlarged view showing the positioning configuration of the process unit 40 by the left side plate frame 74, and Figure 6(b) is a rear view and an enlarged view showing the positioning configuration of the process unit 40 by the right side plate frame 75.

[0035] 5, the process unit 40 has a left side surface 30L and a right side surface 30R, which are end surfaces in a longitudinal direction LD parallel to the X direction. A left positioning boss 41L and a left rotation restriction boss 42L are provided on the left side surface 30L, and a right positioning boss 41R (not shown) and a right rotation restriction boss 42R (not shown) are provided on the right side surface 30R. The left positioning boss 41L and the right positioning boss 41R are located upstream of the left rotation restriction boss 42L and the right rotation restriction boss 42R, respectively, in the installation direction AD of the process unit 40.

[0036] In the present embodiment, the process unit 40 is provided with boss-shaped positioning bosses and rotation restricting bosses, but the present invention is not limited to this. That is, the process unit 40 may be provided with positioning portions and rotation restricting portions that are not boss-shaped.

[0037] The device body 2 of the image forming device 1 has a left plate frame 74 and a right plate frame 75 made of sheet metal members, and these left plate frame 74 and right plate frame 75 face each other with a gap in the longitudinal direction LD.

[0038] As shown in FIGS. 5 and 6(a), the left side plate frame 74 has a first left surface 81Lf and a second left surface 82Lf extending in the installation direction AD (Y direction) and the Z direction. The second left surface 82Lf is disposed inward of the device body 2 by a distance X1 from the first left surface 81Lf in the longitudinal direction LD by drawing the first left surface 81Lf. In other words, the first left surface 81Lf and the second left surface 82Lf are not coplanar. In this embodiment, the second left surface 82Lf is configured as a surface parallel to the installation direction AD (Y direction) and the Z direction, but is not limited to this. For example, the second left surface 82Lf may be a curved surface along the installation direction AD (Y direction) and the Z direction.

[0039] The first left surface 81Lf is formed with a left positioning portion 81L with which the left positioning boss 41L can engage, and the left positioning portion 81L is a notch that is open on the upstream side in the installation direction AD. The second left surface 82Lf is formed with a left rotation restricting portion 82L with which the left rotation restricting boss 42L can engage, and the left rotation restricting portion 82L is a U-shaped notch that is open on the upstream side in the installation direction AD. Note that, because the second left surface 82Lf is formed by drawing, a slope that guides the left positioning boss 41L toward the left positioning portion 81L may be formed.

[0040] 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.

[0041] Similarly, as shown in FIGS. 5 and 6(b), the right side plate frame 75 has a right first surface 81Rf and a right second surface 82Rf extending along the installation direction AD (Y direction) and the Z direction. The right second surface 82Rf is disposed inward of the device body 2 by a distance X2 from the right first surface 81Rf in the longitudinal direction LD by drawing the right first surface 81Rf. In other words, the right first surface 81Rf and the right second surface 82Rf are not coplanar. In this embodiment, the right first surface 81Rf and the right second surface 82Rf are configured as surfaces parallel to the installation direction AD (Y direction) and the Z direction, but are not limited thereto. For example, the right second surface 82Rf may be a curved surface along the installation direction AD (Y direction) and the Z direction.

[0042] The right first surface 81Rf is formed with a right positioning portion 81R with which the right positioning boss 41R can engage, and the right positioning portion 81R is a notch that is open on the upstream side in the installation direction AD. The right second surface 82Rf is formed with a right rotation restricting portion 82R with which the right rotation restricting boss 42R can engage, and the right rotation restricting portion 82R is a U-shaped notch that is open on the upstream side in the installation direction AD. Note that, because the right second surface 82Rf is formed by drawing, a slope that guides the right positioning boss 41R toward the right positioning portion 81R may be formed.

[0043] Since the first right surface 81Rf and the second right surface 82Rf are spaced apart by the distance X2 in the longitudinal direction LD, the right rotation restricting portion 82R is also spaced apart by the distance X2 in the longitudinal direction LD from the right positioning portion 81R. In other words, the right rotation restricting portion 82R is located at a different position from the right positioning portion 81R in the longitudinal direction LD.

[0044] 7 is a perspective view showing the image forming apparatus 1 with the process unit 40 attached. As shown in FIGS. 5 to 7, when the process unit 40 is attached to the apparatus body 2, the left positioning boss 41L and the left rotation restricting boss 42L of the process unit 40 engage with the left positioning portion 81L and the left rotation restricting portion 82L of the left side plate frame 74, respectively. Similarly, when the process unit 40 is attached to the apparatus body 2, the right positioning boss 41R and the right rotation restricting boss 42R of the process unit 40 engage with the right positioning portion 81R and the right rotation restricting portion 82R of the right side plate frame 75, respectively.

[0045] The process unit 40 is positioned in the installation direction AD by the left positioning boss 41L and the right positioning boss 41R engaging with the left positioning portion 81L and the right positioning portion 81R, respectively. Furthermore, the left rotation restriction boss 42L and the right rotation restriction boss 42R engaging with the left rotation restriction portion 82L and the right rotation restriction portion 82R, respectively, restricts rotational movement of the process unit 40 about the left positioning boss 41L and the right positioning boss 41R. In other words, the process unit 40 is positioned in the Z direction.

[0046] In this state, the process unit 40 is fixed from the rear side to the front side to the left side plate frame 74 and the right side plate frame 75 by left and right fixing members 79L, 79R (see FIG. 19(b)) described later.

[0047] In this embodiment, the left positioning portion 81L and the left rotation restricting portion 82L are provided on the same sheet metal member, the left side frame plate 74. This reduces cumulative tolerances and improves the positioning accuracy of the process unit 40. Furthermore, because the left positioning portion 81L is located upstream of the left rotation restricting portion 82L in the mounting direction AD, the cutout shape of the left positioning portion 81L formed in the first left surface 81Lf can be formed with a relatively small area. By reducing the area of ​​the cutout formed in the left side frame plate 74, the rigidity of the left side frame plate 74 can be maintained. Maintaining the rigidity of the left side frame plate 74 improves the positioning accuracy of the process unit 40 relative to the device body 2. Furthermore, since the left side frame plate 74 does not need to be thick, it can be made lighter and less expensive. The same applies to the right side frame plate 75.

[0048] [Developer container] Next, the developing container 230 and its peripheral configuration will be described with reference to Figures 8 and 9. As shown in Figure 8, the developing container 230 is composed of a storage section 18 and a supply section 200 that communicates with the storage section 18 and receives toner supplied from the outside when the process unit 40 is attached to the apparatus main body 2. The supply section 200 has an operation section 201, a cylindrical toner receiving section 202, a supply path section 203 that connects the toner receiving section 202 and the storage section 18, and a main body shutter section 206 that serves as a main body shutter. A side opening 205 that connects to the supply path section 203 is formed in the inner wall of the toner receiving section 202.

[0049] As shown in Figure 9, a supply pack 210, which will be described later, is attached to the supply unit 200, and the toner discharged from the supply pack 210 is supplied to the storage unit 18 through an opening 207 in the main body shutter unit 206, a side opening 205 in the toner receiving unit 202, and the supply path unit 203.

[0050] 8 and 9, the supply path portion 203 is connected to one end of the container 18 in the longitudinal direction of the developer container 230, i.e., the X direction. As shown in FIG. 9, an agitator 60 is provided inside the container 18, rotating about a rotation shaft 60a extending in the X direction. The agitator 60 has blade portions 60b fixed to the rotation shaft 60a, and is driven to rotate by the drive motor 311 to agitate the toner in the container 18 and transport the toner toward the developing roller 12. In the present embodiment, the agitator 60 is composed of the rotation shaft 60a and the blade portions 60b, but a spiral-shaped agitator may also be used to distribute the toner throughout the entire length of the container 18.

[0051] The agitating member 60 also circulates the toner that has not been used for development and has been scraped off from the developing roller 12 within the storage section 18, thereby homogenizing the toner within the storage section 18. The agitating member 60 is not limited to a rotating type. For example, an agitating member that oscillates may also be used. Furthermore, in addition to the agitating member 60, another agitating member may also be provided.

[0052] The storage unit 18 is also provided with a remaining amount detection unit 312 for detecting the amount of toner in the storage unit 18, and the remaining amount detection unit 312 has a light-emitting unit 312a and a light-receiving unit 312b. Light emitted from the light-emitting unit 312a passes through the interior of the storage unit 18 and is received by the light-receiving unit 312b. In other words, the light-emitting unit 312a and the light-receiving unit 312b form an optical path Q1 inside the storage unit 18. The light-emitting element and the light-receiving element of the light-emitting unit 312a and the light-receiving unit 312b may be disposed inside the storage unit 18, or the light-emitting element and the light-receiving element may be disposed outside the storage unit 18, and the light may be guided inside and outside the storage unit 18 by a light-guiding unit.

[0053] Furthermore, light-emitting element 312a and light-receiving element 312b are provided in the central portion of storage unit 18 in the X direction. By providing light-emitting element 312a and light-receiving element 312b in the central portion of storage unit 18, it is possible to accurately detect the remaining amount of toner in storage unit 18. That is, while developer (toner) may be unevenly distributed at the ends of storage unit 18 in the X direction, the central portion of storage unit 18 has less uneven distribution of developer, making it possible to detect the actual remaining amount of toner.

[0054] In this embodiment, an LED is used for the light-emitting unit 312a, and a phototransistor that is turned on by light from the LED is used for the light-receiving unit 312b, but the present invention is not limited to this. For example, a halogen lamp or a fluorescent lamp may be used for the light-emitting unit 312a, and a photodiode or an avalanche photodiode may be used for the light-receiving unit 312b.

[0055] [Supply Department] Next, the supply unit 200 will be described with reference to FIGS. 10(a) to 11(c). The discharge tray 14 is supported so as to be openable and closable between a closed position where the recording material P can be stacked as shown in FIG. 10(a) and an open position where the discharge tray 14 is open relative to the apparatus body 2 of the image forming apparatus 1 as shown in FIG. 10(b). The discharge tray 14 covers the supply unit 200 in the closed position. When the discharge tray 14 is opened to the open position, the top surface 240 and the supply unit 200 disposed on the top surface 240 are exposed. As shown in FIG. 10(c), the supply unit 200 is configured to have a detachable supply pack 210, allowing a user or service technician to replenish toner from the outside without removing the developing container 230 from the apparatus body 2 (housing 72). Hereinafter, users and service technicians are collectively referred to as users.

[0056] Furthermore, the supply unit 200 is disposed on the same side as the cassette 4 in the Y direction with respect to the photosensitive drum 11. In other words, in a plan view, the supply unit 200 is disposed on one side (the front side) of the photosensitive drum 11, which is the same side as the cassette 4, and an opening 91 (see FIG. 17(b)), which will be described later, is disposed on the other side (the rear side) with respect to the photosensitive drum 11. This allows the supply of both toner and recording material P to be performed on the front side of the image forming apparatus 1, improving usability.

[0057] 10(b) and 10(c), the operation unit 201 is disposed on the top surface 240 and forms a supply port 204, which is an inlet for replenishing toner. The operation unit 201 is provided so as to surround the supply port 204 and has a ring portion 201a rotatably supported on the top surface 240 or the toner receiving portion 202, and a lever portion 201b integrally provided with the ring portion 201a. The operation unit 201 is a member for operating the opening and closing of the main body shutter 206 and the pack shutter 214 from the outside.

[0058] As shown in FIG. 11(a), the toner receiving portion 202 is disposed inside the main body shutter portion 206 and is provided with guide portions 247 and 248 that are integral with the toner receiving portion 202. The main body shutter portion 206 is a cylindrical member that is concentric with the toner receiving portion 202 and is provided rotatably inside the toner receiving portion 202. The main body shutter portion 206 has an opening 207 (see FIG. 11(c)), and in the closed position shown in FIG. 11(a), the opening 207 and the side opening 205 of the toner receiving portion 202 are misaligned. A seal member 243 is fixed to the main body shutter portion 206 so as to surround the periphery of the opening 207.

[0059] 11(a) is shown by a broken line because it is covered by the main body shutter 206 which is in the closed position. Therefore, the side opening 205 is blocked by the main body shutter 206, and the toner is not discharged into the supply path 203.

[0060] 11(c), the opening 207 overlaps with the side opening 205 of the toner receiving section 202. Therefore, the toner supplied from the supply pack 210 (see FIG. 11(c)) attached to the supply section 200 can be discharged to the supply path section 203 through the side opening 205 and the opening 207.

[0061] The main body shutter 206 is provided with a main body shutter drive transmission protrusion 206a, which will be described in detail later, and is used to receive drive from the supply pack 210 and rotate the main body shutter 206. When the operation unit 201 is rotated with the supply pack 210 attached to the supply unit 200, the main body shutter 206 moves between a closed position and an open position.

[0062] The operation unit 201 is provided with an operation unit drive transmission protrusion 201d that protrudes radially inward from the inner circumferential surface of the toner receiving unit 202. The operation unit drive transmission protrusion 201d is engaged with a main body shutter drive transmission protrusion 206a via a pair of drive transmission surfaces 214b (see FIG. 14(b)) of the pack shutter 214 of the supply pack 210. When the user rotates the lever portion 201b of the operation unit 201 counterclockwise by 90 degrees from the closed position shown in FIG. 11(a) to the open position shown in FIG. 11(c).

[0063] When forming an image on the recording material P, the toner is stirred in the container 18 by the stirring member 60 (see FIG. 9), and the side opening 205 needs to be closed by the main body shutter 206 to prevent the toner from leaking out from the side opening 205. Therefore, during image formation, the operation unit 201 is located in the operating position shown in FIG. 11(a) so that the main body shutter 206 is located in the closed position. On the other hand, when replenishing toner from a replenishing pack 210 (described later) to the container 18, the side opening 205 needs to be opened. Therefore, during toner replenishing, the operation unit 201 is located in the replenishing position shown in FIG. 11(c) so that the main body shutter 206 is located in the open position.

[0064] [Resupply Department Layout and Configuration] Next, a detailed description will be given of the arrangement and configuration of the supply unit 200. Figure 12 is a left side view showing the image forming apparatus 1. In Figure 12, the exterior cover 71 and the left side plate frame 74 are not shown.

[0065] As shown in Fig. 12, the supply unit 200 at least partially overlaps with the scanner unit 50 when viewed in the rotational axis direction (X direction) of the photosensitive drum 11. The portion of the scanner unit 50 that overlaps with the supply unit 200 is indicated by a dotted line in Fig. 12. Specifically, the toner receiving portion 202 and the supply path portion 203 of the supply unit 200 are arranged so as to overlap with the scanner unit 50 when viewed in the rotational axis direction of the photosensitive drum 11. Here, in the horizontal direction (Y direction), the area where the supply port 204 is provided is referred to as area R1, and the area where the scanner unit 50 is provided is referred to as area R2. In this case, area R1 overlaps with area R2 when viewed in the rotational axis direction of the photosensitive drum 11.

[0066] An imaginary plane that passes through the uppermost end portion 18b of the frame 18a of the storage unit 18 and is parallel to the horizontal plane is defined as an imaginary plane S. The imaginary plane S is indicated by a dashed line in FIG. 12 . The entire operation unit 201 of the supply unit 200, a part of the toner receiving unit 202, and a part of the supply path 203 are located above the imaginary plane S. In other words, a part of the supply unit 200 is located above the imaginary plane S. Furthermore, a part of the parts of the toner receiving unit 202 and the supply path 203 that are above the imaginary plane S overlaps with the scanner unit 50 when viewed in the direction of the rotation axis of the photosensitive drum 11.

[0067] On the other hand, a portion of the storage section 18 also overlaps with the drum frame 11a when viewed in the direction of the rotation axis of the photosensitive drum 11, as indicated by a dashed line in Fig. 12. In this way, by increasing the volume of the storage section 18, it is possible to increase the toner capacity that the storage section 18 can accommodate. The drum frame 11a rotatably supports the photosensitive drum 11, and the storage section 18 rotatably supports the developing roller 12 that carries the developer.

[0068] FIG. 13 is a plan view showing the image forming apparatus 1 without the exterior cover 71 shown. In the X direction, the width X3 of the supply port 204 is shorter than the width X4 of the storage section 18. The laser light irradiated from the scanner unit 50 to the photosensitive drum 11 spreads into a trapezoidal shape as shown in FIG. 13 due to the action of a polygon mirror and a lens (neither of which are shown). Therefore, in the X direction, the width X5 of the scanner unit 50 is shorter than the width X6 of the photosensitive drum 11. As a result, a space is created between the left end of the scanner unit 50 and the left side plate frame 74, and in this embodiment, the supply section 200 is provided in that space.

[0069] Furthermore, in the X direction, the supply unit 200 (width X3) and the scanner unit 50 (width X5) are provided side by side within the area (width X4) where the storage unit 18 is provided. This makes it possible to reduce the impact of providing the supply unit 200 on the size of the image forming apparatus 1.

[0070] Moreover, the process unit 40 is arranged so that at least a portion thereof overlaps the scanner unit 50 in a plan view. Furthermore, as shown in FIG. 20(a), the process unit 40 is arranged so that at least a portion thereof overlaps the fixing unit 9 in a plan view. This arrangement of the process unit 40, the scanner unit 50, and the fixing unit 9 makes it possible to increase the toner capacity of the storage unit 18 without increasing the size of the image forming apparatus 1. Note that the arrangement of the process unit 40, the scanner unit 50, and the fixing unit 9 is not limited to the arrangement described above.

[0071] 3, the supply unit 200 is disposed on the opposite side of the drive motor 311 in the rotational axis direction (X direction) of the photosensitive drum 11, when the position of the scanner unit 50 is used as a reference. In this embodiment, a relatively small drive motor 311 is used, and therefore, as shown in FIG. 12, the drive motor 311 and the supply unit 200 do not overlap in the Z direction. However, since the supply unit 200 is disposed on the opposite side of the scanner unit 50 as described above, the drive motor 311 can be replaced with a larger one that overlaps with the supply unit 200 in the Z direction. This improves design flexibility.

[0072] [Supply Pack] Next, the configuration of the supply pack 210 will be described with reference to Figures 14(a) to 16(b). Figures 14(a) and 14(b) are perspective views showing the supply pack when the pack shutter 214 is in the closed position. Figures 15(a) and 15(b) are perspective views showing the supply pack when the pack shutter 214 is in the open position. Figures 16(a) and 16(b) are exploded perspective views showing the supply pack.

[0073] Replenishment pack 210, which serves as a toner container, has pouch portion 211, which is a bag containing toner to be replenished, cylindrical insertion portion 212 that is inserted into replenishing port 204, and pack shutter portion 214 that serves as a container shutter. Insertion portion 212, which serves as a nozzle, communicates with pouch portion 211. Insertion portion 212 has opening 213 formed therein as an opening through which toner in pouch portion 211 is discharged to the outside. Pouch portion 211 is made of a plastic bag that is easily deformable, but is not limited to this. For example, pouch portion 211 may be made of a resin bottle container, or a paper or vinyl container.

[0074] A pouch end 216 is formed in the pouch portion 211 at the end opposite to the insertion portion 212. The pouch portion 211 has a flattened shape toward the pouch end 216, and the pouch end 216 extends in a radial direction perpendicular to the rotation axis direction of the pack shutter portion 214.

[0075] The pack shutter 214 is a cylindrical member concentric with the insertion portion 212, and is provided radially outward of the insertion portion 212. The pack shutter 214 has an opening 214c, and by rotating relative to the insertion portion 212, it can transition between a closed position that blocks the opening 213 of the insertion portion 212 and an open position that opens the opening 213. When the opening 214c of the pack shutter 214 and the opening 213 of the insertion portion 212 overlap, toner can be replenished from the replenishment pack 210 to the replenishment portion 200.

[0076] In addition, a seal member 231 that can slide against the outer surface of the insertion portion 212 is fixed to the inner surface of the pack shutter portion 214, and the seal member 231 blocks the opening 213 of the insertion portion 212 when the pack shutter portion 214 is positioned in the closed position.

[0077] 16(a), the insertion portion 212 is formed with guided portions 232 recessed from the outer circumferential surface of the insertion portion 212, and each guided portion 232 has a pair of first guided portions 232a and second guided portions 232b. When the supply pack 210 is attached to the supply unit 200, guide portions 247, 248 integral with the toner receiving portion 202 fit into the guided portions 232. This restricts relative movement between the insertion portion 212 and the toner receiving portion 202 in the circumferential direction around the rotation axis of the pack shutter 214.

[0078] 16(b), the outer peripheral surface of the pack shutter 214 is provided with an alignment portion 217 that engages with the operating portion 201, and a drive transmission surface 214b that faces the alignment portion 217 in the circumferential direction of the outer periphery of the pack shutter 214. That is, a groove (a recess that recesses inward in the radial direction of the pack shutter 214) is formed in the outer peripheral surface of the pack shutter 214, with the alignment portion 217 serving as the groove bottom surface (recess bottom surface) and the drive transmission surface 214b serving as the groove side surface. This groove is open at the tip of the outer peripheral surface of the pack shutter 214 in the insertion direction of the insertion portion 212. The drive transmission surface 214b receives a force in the circumferential direction from the operating portion drive transmission protrusion 201d of the operating portion 201, causing the pack shutter 214 to rotate relative to the insertion portion 212.

[0079] When the pack shutter 214 is in the closed position, the insertion portion 212 is in a state in which an opening 214c provided in the pack shutter 214 and a guided portion 232 recessed from the outer circumferential surface of the insertion portion 212 overlap with each other in the circumferential rotation phase. In this state, the guide portions 247, 248 of the supply unit 200 are inserted into the guided portion 232 of the supply pack 210, and the opening 214c fits into the periphery of a seal member 243 provided on the inner circumferential surface of the main body shutter 206. When the supply pack 210 is attached to the supply unit 200, of the guided portion 232, a first guided portion 232a on the upstream side in the insertion direction engages with the guide portion 247, and a second guided portion 232b on the downstream side faces the guide portion 248. A surface extending in the circumferential direction, which is a step portion between first guided portion 232a and second guided portion 232b, engages in the insertion direction with a surface extending in the circumferential direction, which is a step portion between guide portion 247 and guide portion 248, and determines the position in the insertion direction between insertion portion 212 and operating portion 201. Opening 214c has a notched shape that widens in width toward the tip side of insertion portion 212. A pair of opposing portions that face each other in the circumferential direction and form opening 214c sandwich seal member 243 in the circumferential direction.

[0080] The drive transmission surface 214b of the pack shutter 214 engages with the operation unit drive transmission protrusion 201d of the operation unit 201 and also engages with the main body shutter drive transmission protrusion 206a of the main body shutter 206. The pack shutter 214 moves (rotates) due to the operation (operation) force of the operation unit 201, and transmits the operation force to the main body shutter 206, causing the main body shutter 206 to move as well. In other words, the drive transmission surface 214b has an area that engages and abuts with the operation unit drive transmission protrusion 201d as a force receiving area. The operation unit drive transmission protrusion 201d has a convex shape that extends radially inward from the inner circumferential surface of the operation unit 201, and the drive transmission surface 214b has an area that engages and abuts with the main body shutter drive transmission protrusion 206a as a force applying area.

[0081] [Toner replenishment procedure] Next, a procedure for replenishing toner using the replenishing pack 210 will be described with reference to Figures 10(a) to 16(b). First, as shown in Figures 10(a) to 10(c), the user removes the recording material P on the discharge tray 14 and opens the discharge tray 14 from the closed position to the open position. This exposes the replenishing unit 200. The replenishing unit 200 is provided on the upper front surface of the image forming apparatus 1, making it easy to replenishing toner.

[0082] When the discharge tray 14 is opened to the open position and the supply unit 200 is exposed, the operation unit 201 is positioned in the operating position. Then, the user aligns the operation unit drive transmission protrusion 201d (see FIG. 11(a)) provided on the supply unit 200 with the alignment notch 217 (see FIG. 16(b)) provided on the supply pack 210, and attaches the supply pack 210 to the supply unit 200. If the positions of the operation unit drive transmission protrusion 201d and the alignment notch 217 do not match, the supply pack 210 will interfere with the operation unit drive transmission protrusion 201d, and the supply pack 210 cannot be inserted.

[0083] 10(c) is a perspective view showing the state in which the supply pack 210 is attached to the supply unit 200. In this embodiment, as shown in FIG. 10(c), the supply pack 210 can be attached to the supply unit 200 when the direction of arrow D, which is the extension direction of the pouch end 216, is parallel to the X direction. When the supply pack 210 is inserted all the way into the supply unit 200, the drive transmission surface 214b forming the alignment notch 217 engages with the operation unit drive transmission protrusion 201d of the operation unit 201. In addition, the drive transmission surface 214b of the pack shutter 214 engages with the main body shutter drive transmission protrusion 206a of the main body shutter 206.

[0084] That is, the rotation of operation unit 201 is transmitted to pack shutter unit 214, and the rotation of pack shutter unit 214 is transmitted to main body shutter unit 206. As a result, main body shutter unit 206 and pack shutter unit 214 engage with each other and become integrated, and operation unit 201, pack shutter unit 214, and main body shutter unit 206 move in conjunction with each other.

[0085] 11(c), the user rotates the lever portion 201b of the operating portion 201 counterclockwise by 90 degrees. This rotates the operating portion 201 from the operating position to the replenishing position, and the pack shutter portion 214 and the main body shutter portion 206 rotate from the closed position to the open position. As a result, the opening 214c of the pack shutter portion 214, the opening 213 of the insertion portion 212 of the replenishing pack 210, the opening 207 of the main body shutter portion 206, and the side opening 205 of the toner receiving portion 202 are aligned. This causes the toner in the replenishing pack 210 to be discharged into the storage portion 18 through the replenishing path portion 203.

[0086] In other words, when the operating unit 201 is located at the replenishing position, the replenishing unit 200 is in a replenishing state in which toner can be replenished from the replenishing pack 210 to the storage unit 18. At this time, the opening 213 of the replenishing pack 210 and the side opening 205 of the toner receiving unit 202 are in communication with each other.

[0087] When the toner supply from the supply pack 210 to the storage unit 18 is complete, the user returns the operation unit 201 from the supply position to the operating position. That is, the user rotates the lever portion 201b of the operation unit 201 clockwise by 90 degrees. This causes the pack shutter portion 214 and the main body shutter portion 206 to rotate from the open position to the closed position.

[0088] In other words, when the operating unit 201 is in the operating position, the supply unit 200 is in a non-supply state where toner can be supplied from the supply pack 210 to the storage unit 18. At this time, the opening 213 of the supply pack 210 and the side opening 205 of the toner receiving unit 202 do not communicate with each other.

[0089] Then, the user removes the supply pack 210 from the supply unit 200. In this manner, when the supply pack 210 is removed from the supply unit 200, the pack shutter 214 is in the closed position, so that toner leakage from the opening 213 of the supply pack 210 can be prevented.

[0090] [Rear cover and transfer unit] Next, the peripheral configuration of the rear cover 73 and the transfer unit 7 will be described using FIGS. 17(a) to 18(d). The rear of the image forming apparatus 1 is provided with an opening 91 formed by an exterior cover 71 and a rear cover 73 that covers the opening 91, as shown in FIGS. 17(a) to 18(d). The rear cover 73 as a cover is supported so as to be openable and closable around a cover engagement portion 73d between a closed position, which is a second closed position in which the rear cover 73 is closed relative to the device body 2, and an open position, which is a second open position in which the rear cover 73 is open relative to the device body 2. In the closed position, the rear cover 73 covers the opening 91, the transfer unit 7, and the process unit 40, and in the open position, the rear cover 73 opens the opening 91 to expose the transfer unit 7 and the process unit 40. The transfer unit 7 as an open / close portion is supported so as to be openable and closable around a pivot shaft 7c.

[0091] An outer surface 73b of the rear cover 73, i.e., a surface that constitutes the exterior surface of the housing 72, is provided with a grip portion 73c that can be gripped by a user when opening or closing the rear cover 73. An inner surface 73f of the rear cover 73 opposite the outer surface 73b is provided with a plurality of (three in this embodiment) engaging claws 73a, a plurality of transport ribs 73g, and a pressing rib 73e.

[0092] The rear cover 73 is held in the closed position shown in Figures 17(a) and 18(a) by the engagement of the engagement claws 73a with the exterior cover 71. Furthermore, when the rear cover 73 is in the closed position, the transfer unit 7 is pulled into the inside of the apparatus main body 2 by links 96L and 96R (see Figure 21), which will be described later, and remains in the closed state until operated by the user. When the transfer unit 7 is in the closed position, the transfer roller 7a transfers the toner image carried on the photosensitive drum 11 onto the recording material P.

[0093] As shown in Figures 17(b) and 18(b), when the rear cover 73 is opened to the open position, the duplex conveying path 16, through which the recording material P conveyed by the duplex conveying roller pair 5d passes, is opened. The duplex conveying path 16 is formed by a plurality of conveying ribs 73g of the rear cover 73 and a plurality of conveying ribs 16a formed on the outer surface of the transfer unit 7. In other words, the conveying ribs 73g form part of the duplex conveying path 16 when the rear cover 73 is located in the closed position. That is, the rear cover 73 is movable between a closed position where it covers the duplex conveying path 16 and an open position where it exposes and opens the duplex conveying path 16 to the outside. The duplex conveying path 16 and the conveying path 19 are conveying paths through which the recording material P is conveyed.

[0094] Furthermore, the pressure roller 9b of the fixing unit 9 is brought into contact with or separated from the heating film 9a by a link (not shown) in conjunction with the opening and closing of the rear cover 73. Therefore, when the rear cover 73 is in the open position and the double-sided conveying path 16 is open, the pressure roller 9b is separated from the heating film 9a.

[0095] Next, as shown in FIGS. 17(c) and 18(c), when the transfer unit 7 is opened around the pivot shaft 7c with the rear cover 73 in the open position, the conveying path 19 is opened. The recording material P, which is fed by the pickup roller 3 and conveyed by the conveying roller pair 5c, the transfer nip N1, and the fixing nip N2, passes through the conveying path 19. That is, the transfer unit 7 can be opened and closed between a closed position (first closed position) in which the conveying path 19 is covered and closed relative to the device body 2, and an open position (first open position) in which the conveying path 19 is exposed to the outside and opened relative to the device body 2. Note that the conveying path 19 can be opened even when the process unit 40 is attached to the device body 2 when the transfer unit 7 is in the open position.

[0096] The inner surface of the transfer unit 7 is provided with transport ribs 19a that form the transport path 19. The outer surface of the transfer unit 7 is provided with a plurality of transport ribs 16a and a grip portion 7b (see FIG. 17(b)), and the transfer unit 7 is rotated between a closed position and an open position by the user operating the grip portion 7b.

[0097] [Jam Clearance] Next, a jam clearance method will be described when a jam occurs in the double-sided conveying path 16 or the conveying path 19. When a jam of recording material P occurs during image formation operation, the user opens the rear cover 73 from the closed position to the open position, as shown in Figures 17(a) and 17(b) and 18(a) and 18(b). This opens the double-sided conveying path 16, and when a jam occurs near the double-sided conveying path 16, the jammed recording material P can be removed.

[0098] On the other hand, if a jam occurs near the transfer nip N1, the user opens the rear cover 73 and the transfer unit 7 to the open position, as shown in Figures 17(c) and 18(c). This opens the conveying path 19, allowing the user to remove the recording material P that has jammed near the conveying path 19. In this way, even if a jam occurs in the double-sided conveying path 16 or the conveying path 19, the jam can be cleared from the rear side of the image forming apparatus 1 while the process unit 40 remains attached to the apparatus main body 2. This makes jam clearance less cumbersome and improves jam clearance efficiency.

[0099] After the jam removal is complete, the user closes the rear cover 73 from the open position to the closed position while leaving the transfer unit 7 in the open position, as shown in FIG. 18(d). The rear cover 73 then rotates independently until it is closed approximately 25° from the open position. The pressing rib 73e of the rear cover 73 then comes into contact with the pressed portion 7d of the transfer unit 7. As the rear cover 73 continues to close toward the closed position, the transfer unit 7 is also pressed by the pressing rib 73e, moving from the open position to the closed position. This eliminates the need to close the transfer unit 7, improving usability. The user can also close the transfer unit 7 before closing the rear cover 73.

[0100] [Attaching and detaching the process unit] 19(a) to 20(d), a method for attaching and detaching the process unit 40, for example, when replacing or maintaining the process unit 40, will be described. When removing the process unit 40 from the apparatus main body 2, the user moves the rear cover 73 and the transfer unit 7 to the open position, as shown in FIGS. 19(a) and 19(b) and 20(a) and 20(b), in the same way as in the jam clearance described above. This exposes the process unit 40 to the outside, but in this state, the process unit 40 is fixed to the left side plate frame 74 and the right side plate frame 75 by fixing members 79L and 79R.

[0101] In this embodiment, the process unit 40 is fixed to the left plate frame 74 and the right plate frame 75 using fixing members 79L, 79R made of sheet metal and screws, but this is not limiting. For example, the process unit 40 may be held in the device body 2 by a biasing member such as a spring, or the process unit 40 may be held in the device body 2 by using the biasing force of the transfer roller 7a of the transfer unit 7 against the photosensitive drum 11.

[0102] To remove the process unit 40 from the apparatus main body 2, first, the fixing members 79L and 79R are removed. Then, the drive transmission between the pinion gear of the drive motor 311 and the photosensitive drum 11 is disengaged, and the process unit 40 is moved in the removal direction DD, which is opposite to the installation direction AD (see FIG. 5), as shown in FIGS. 19(c) and 20(c). This causes the left positioning boss 41L and the right positioning boss 41R to move away from the left positioning portion 81L and the right positioning portion 81R, and the left rotation restricting boss 42L and the right rotation restricting boss 42R to move away from the left rotation restricting portion 82L and the right rotation restricting portion 82R. In other words, the process unit 40 can be attached to and detached from the housing 72 of the apparatus main body 2 through the opening 91 when the rear cover 73 is in the open position and the transfer unit 7 is in the open position. The opening 91 is located at the rear of the apparatus main body 2 and can occupy a relatively large area, which makes it easy to attach and detach the process unit 40 and improves the ease of maintenance of the process unit 40.

[0103] In this embodiment, the fixing unit 9 is held by a fixing stay 78 suspended between the left side plate frame 74 and the right side plate frame 75. In order to reduce the size of the image forming apparatus 1, the supply unit 200, which is part of the process unit 40, overlaps with the fixing unit 9 in the X direction and the Z direction. In other words, the supply unit 200 is disposed upstream of the fixing unit 9 in the removal direction DD, and is disposed so that at least a portion of the supply unit 200 overlaps with the fixing unit 9 when viewed in the removal direction DD.

[0104] 19(d) and 20(d), the user moves the process unit 40 in the removal direction DD while rotating it about an axis parallel to the X direction in the process of pulling out the process unit 40 from the device body 2. The fixing stay 78 is also provided with a notch 78a, which allows the supply part 200 to pass through the notch 78a when the process unit 40 is pulled out from the device body 2.

[0105] The process unit 40 may be configured so as not to overlap the fixing unit 9 in the pulling-out direction DD, so that the process unit 40 can be pulled out in the pulling-out direction DD without being rotated. Also, the process unit 40 may be configured so as not to overlap the fixing unit 9 in the Z direction, so that the process unit 40 can be pulled out in the negative Y direction, for example.

[0106] To mount the process unit 40 in the apparatus main body 2, the procedure for removing the process unit 40 described above is performed in reverse. That is, the process unit 40 is mounted in the mounting direction AD (see FIG. 5) while being rotated about the X-axis relative to the apparatus main body 2.

[0107] As described above, in the present embodiment, in the toner supply type image forming apparatus 1, jam clearance and the installation and removal of the process unit 40 are performed through the same opening 91 on the rear side of the image forming apparatus 1. This allows, for example, the area occupied by the movement path of the process unit 40 when installing or removing the process unit 40 to be reduced, thereby improving the space efficiency within the image forming apparatus 1. Furthermore, the opening 91 can have a relatively large area, improving the workability of installing or removing the process unit 40 and of clearing jams. This allows the toner capacity stored in the storage section 18 to be increased while the main body size is reduced, and jam clearance and maintainability of the process unit 40 can be improved.

[0108] Link Configuration 21 to 28(b), the configuration of the links 96L, 96R for stably holding the transfer unit 7 at the closed position and the open position will be described. As shown in Fig. 21 to Fig. 23(d), the device main body 2 is provided with links 96L, 96R, link holders 97L, 97R, and tension springs 98L, 98R as urging portions.

[0109] More specifically, a link holder 97L is fixed to the left side plate frame 74 with a screw, and a link 96L connects the link holder 97L and the transfer unit 7. A tension spring 98L is provided between the link 96L and a spring hook 74a provided on the left side plate frame 74.

[0110] Similarly, a link holder 97R is fixed to the right side plate frame 75 with screws, and the link holder 97R and the transfer unit 7 are connected by a link 96R. A tension spring 98R is provided between the link 96R and a spring hook (not shown) provided on the right side plate frame 75. The link 96R, link holder 97R, and tension spring 98R provided on the right side (positive X direction) of the transfer unit 7 have the same configuration as the link 96L, link holder 97L, and tension spring 98L provided on the left side (negative X direction) of the transfer unit 7. For this reason, the following description will mainly focus on the link 96L, link holder 97L, tension spring 98L, and their surrounding configuration, and a description of the link 96R, link holder 97R, tension spring 98R, and their surrounding configuration will be omitted.

[0111] As shown in Figures 22(a) to 23(d), the link holder 97L fixed to the left side plate frame 74 has a protrusion 97Lg that protrudes toward the rear side (negative Y direction) of the image forming apparatus 1. An upper surface 97Lh of the protrusion 97Lg extends parallel to the Y direction, and the surface of the protrusion 97Lg facing the negative Y direction forms an abutment surface 97Lb. A recess 97Li is provided at the bottom of the abutment surface 97Lb. The protrusion 97Lg is also provided with a substantially triangular retaining hole 97La that extends in the X direction.

[0112] The link 96L has a pivot shaft 96La that engages with the retaining hole 97La with a gap therebetween, a link shaft 96Lb, and a link hole 96Lc that is provided on the opposite side of the link shaft 96Lb from the pivot shaft 96La. The pivot shaft 96La is sufficiently smaller than the retaining hole 97La and is configured to be movable within the retaining hole 97La. A tension spring 98L is engaged with the link shaft 96Lb, and the tension spring 98L biases the link shaft 96Lb toward the spring hook 74a. An engagement portion 7L of the transfer unit 7 engages with the link hole 96Lc. The engagement portion 7L has a shaft that extends from the transfer unit 7 in the minus X direction and passes through the link hole 96Lc, and a rib provided at the tip of the shaft to prevent it from coming off.

[0113] 22(a) to 22(d), when the transfer unit 7 is in the closed position, the link shaft 96Lb of the link 96L is urged in the Y direction toward the device main body 2 by the tension spring 98L. The transfer unit 7 is urged in the Y direction toward the device main body 2 by the engagement portion 7L being urged by the link hole portion 96Lc of the link 96L, and is stably held in the closed position.

[0114] As shown in FIGS. 23(a) to 24(a), when the transfer unit 7 is in the open position, a spring bent portion 96Lg provided near the pivot shaft 96La of the link 96L abuts against the tension spring 98L. The tension spring 98L is pressed by the spring bent portion 96Lg, causing it to bend near the spring bent portion 96Lg. In this embodiment, the tension spring 98L is made of a coil spring, but is not limited to this. For example, the tension spring 98L may be made of a torsion bar or the like.

[0115] At this time, the link shaft 96Lb of the link 96L engages with a recess 97Li provided at the bottom of the abutment surface 97Lb. Furthermore, the tension spring 98L is bent by the spring bending portion 96Lg, and thus the link shaft 96Lb of the link 96L is biased toward the pivot shaft 96La by the tension spring 98L. Because the recess 97Li is recessed in the direction toward the pivot shaft 96La, the link shaft 96Lb is stably held by the recess 97Li. Therefore, when a moment acts in the opening direction around the pivot shaft 7c due to its own weight, the transfer unit 7 is stably held in the open position by the engagement of the engagement portion 7L with the link hole 96Lc of the link 96L.

[0116] Next, using Figures 24(a) to 27(b), we will explain the action of the link 96L when closing the transfer unit 7 from the open position to the closed position. As shown in Figures 24(a) and 24(b), the lower side of the abutment surface 97Lb of the link holder 97L has an arc shape centered on the rotation axis 96La. When the user lifts the transfer unit 7, which is located in the open position, toward the closed position, a moment in the closing direction is transmitted from the transfer unit 7 to the link 96L via the engagement portion 7L and the link hole 96Lc. Then, the link shaft 96Lb of the link 96L moves upward while rubbing against the abutment surface 97Lb.

[0117] As described above, the lower side of the abutment surface 97Lb has an arc shape centered on the rotation axis 96La, and the link axis 96Lb is biased toward the rotation axis 96La by the tension spring 98L. Therefore, the biasing force acting on the link 96L from the tension spring 98L hardly acts as a rotation moment in the closing direction (or opening direction) of the link 96L centered on the rotation axis 96La. Therefore, when opening or closing the transfer unit 7, the user does not feel the biasing force of the tension spring 98L, and can open or close the transfer unit 7 without feeling any discomfort.

[0118] The radius of the arc-shaped contact surface 97Lb is set slightly larger than the distance from the rotation shaft 96La to the link shaft 96Lb, so that the rotation shaft 96La is slightly raised in the minus Y direction from the state where it abuts against the holding hole 97La. Therefore, when the transfer unit 7 is closed from the open position to the closed position, the link shaft 96Lb can reliably slide against the contact surface 97Lb, thereby stabilizing the operation of the link 96L.

[0119] Next, as shown in Figures 25(a) and 25(b), when the user further closes the transfer unit 7, the link 96L does not rotate, and only the transfer unit 7 is closed. Here, the link hole 96Lc of the link 96L has an arc portion 96Lc2 centered on the rotation shaft 7c of the transfer unit 7, a first linear portion 96Lc1, and a second linear portion 96Lc3. The first linear portion 96Lc1 extends from one end of the arc portion Lc2 in a direction away from the rotation shaft 96La. The second linear portion 96Lc3 extends from the other end of the arc portion Lc2 in a direction toward the rotation shaft 96La.

[0120] 24(a) to the state shown in FIG. 24(b), the engaging portion 7L of the transfer unit 7 moves within the first straight portion 96Lc1 toward the arc portion 96Lc2. Because the movement trajectory of the engaging portion 7L intersects with the first straight portion 96Lc1, the link 96L also rotates in conjunction with the rotation of the transfer unit 7.

[0121] When the transfer unit 7 is closed from the position shown in FIG. 25(a) to the position shown in FIG. 25(b), the engaging portion 7L of the transfer unit 7 moves within the arc portion 96Lc2 toward the second straight portion 96Lc3. At this time, the movement trajectory of the engaging portion 7L is along the arc portion 96Lc2, so the link 96L does not rotate even when the transfer unit 7 rotates. Note that the link 96L is able to maintain its position even when the transfer unit 7 is closed from the position shown in FIG. 25(a) to the position shown in FIG. 25(b) because the link shaft 96Lb is biased toward the abutment surface 97Lb by the tension spring 98L. Note that in the positions shown in FIGS. 25(a) and 25(b), the bending of the tension spring 98L due to the spring bending portion 96Lg is released and the link 96L is in a straight position.

[0122] 24(a) to the state shown in Fig. 24(b), and an inertial force in the closing direction is generated in the link 96L, no force from the transfer unit 7 acts on the link 96L while the engaging portion 7L passes through the arc portion 96Lc2. Therefore, the inertial force in the closing direction of the link 96L can be attenuated, and the link 96L can be prevented from closing too quickly.

[0123] Next, as shown in FIGS. 26(a) and 26(b), when the user further closes the transfer unit 7, the engaging portion 7L of the transfer unit 7 moves along the second linear portion 96Lc3. Because the path of movement of the engaging portion 7L intersects with the second linear portion 96Lc3, the link 96L also rotates in conjunction with the rotation of the transfer unit 7. Here, the upper side of the abutment surface 97Lb has an arc shape centered on the spring hook portion 74a, and the link shaft 96Lb is biased toward the rotation shaft 96La by the tension spring 98L. Therefore, the biasing force acting on the link 96L from the tension spring 98L hardly acts as a rotation moment in the closing direction (or opening direction) of the link 96L about the rotation shaft 96La. Therefore, when opening or closing the transfer unit 7, the user does not feel the biasing force of the tension spring 98L, and can open or close the transfer unit 7 without any discomfort.

[0124] When the user is closing the transfer unit 7, the second linear portion 96Lc3 of the link hole 96Lc is pressed by the engaging portion 7L, causing a clockwise moment about the link shaft 96Lb to be generated in the link 96L. Meanwhile, the pivot shaft 96La receives an upward reaction force from the lower surface 97La1 of the retaining hole 97La, causing a counterclockwise moment about the link shaft 96Lb to be generated in the link 96L. These clockwise and counterclockwise moments are balanced. As the user closes the transfer unit 7, the link shaft 96Lb rises while rubbing against the abutment surface 97Lb.

[0125] Next, as shown in Figures 27(a) and 27(b), when the user further closes the transfer unit 7, the link shaft 96Lb passes through the upper end of the abutment surface 97Lb. This disengages the link shaft 96Lb from the abutment surface 97Lb, and the link 96L is rotated in the closing direction by the tension spring 98L. At this time, the link shaft 96Lb moves along the upper surface 97Lh toward the inside of the device main body 2, i.e., toward the spring hook portion 74a. The transfer unit 7 is then biased toward the closed position by the link 96L via the link hole portion 96Lc and the engagement portion 7L, and is stably held in the closed position.

[0126] Next, the manner in which the transfer unit 7 is opened from the state shown in Figure 28(a) to the state shown in Figure 28(b) will be described. As shown in Figures 28(a) and 28(b), when the user opens the transfer unit 7 from the closed position, the second linear portion 96Lc3 of the link hole portion 96Lc is pressed by the engaging portion 7L. As a result, a counterclockwise moment about the link shaft 96Lb is generated in the link 96L.

[0127] Meanwhile, the pivot shaft 96La receives a reaction force in the lower left direction from the upper right surface 97La2 of the retaining hole 97La, causing a clockwise moment about the link shaft 96Lb to be generated in the link 96L. These counterclockwise and clockwise moments are balanced. As the transfer unit 7 is opened by the user, the link shaft 96Lb moves in the negative Y direction while rubbing against the upper surface 97Lh against the biasing force of the tension spring 98L. This brings the transfer unit 7 and the link 96L into the state shown in FIG. 26(b).

[0128] From this point, the procedure for opening the transfer unit 7 to the open position follows the order shown in Figures 26(b)(a), 25(b)(a), and 24(b)(a). However, since this is simply the reverse of the procedure for closing the transfer unit 7 described above, a detailed description will be omitted. Note that in the states shown in Figures 26(b)(a), 25(b)(a), and 24(b)(a), the biasing force acting from the tension spring 98L to the link 96L hardly acts as a rotational moment in the opening direction (closing direction) of the link 96L about the pivot shaft 96La. Therefore, when opening or closing the transfer unit 7, the user does not feel the biasing force of the tension spring 98L, and can open or close the transfer unit 7 without any discomfort.

[0129] [Locking member] Next, as shown in Fig. 21, the locking members 99L, 99R provided at both ends of the transfer unit 7 in the X direction will be described. The locking members 99L, 99R are engaged with the device main body 2 when the image forming apparatus 1 forms an image, thereby restricting the transfer unit 7 from rotating in the open direction from the closed position. Note that the locking members 99L, 99R have the same configuration, and therefore the following description will mainly focus on the locking member 99R and its peripheral configuration, and will omit a description of the locking member 99L and its peripheral configuration.

[0130] Figures 29(a) and (b) are perspective views showing the locking member 99R as viewed from the minus Y direction. Figures 29(c) and (d) are perspective views showing the locking member 99R removed from the transfer unit 7. As shown in Figures 29(a) to (d), the locking member 99R is rotatably supported by a locking shaft 7aR that is provided in the transfer unit 7 and extends in the X direction.

[0131] The locking member 99R has a contact portion 99Ra (see FIG. 31(b)), a tip portion 99Rb, and a butting portion 99Rc. As shown in FIGS. 29(c) and 29(d), the locking member 99R is divided into a first bearing portion 99Rd located on the positive side in the X direction and a second bearing portion 99Re located on the negative side in the X direction. As will be described in detail later, the first bearing portion 99Rd and the second bearing portion 99Re each have a bearing that engages with the locking shaft 7aR. The contact portion 99Ra corresponds to an inner region of the connection portion connecting the first bearing portion 99Rd and the second bearing portion 99Re. Here, "inside" means located inside when viewed from the center of the locking shaft 7aR (see FIG. 31(b)). The tip portion 99Rb is provided on the first bearing portion 99Rd side, and the butting portion 99Rc is provided on the second bearing portion 99Re side. The contact portion 99Ra, the tip portion 99Rb, and the abutment portion 99Rc will be described in detail later.

[0132] Figure 30 is a view of the apparatus main body 2 as seen from the minus Y direction, and Figure 31(a) is a cross-sectional view taken along line 31AB-31AB in Figure 30, showing the image forming apparatus 1 when the locking member 99R is in the unlocked position. Figure 31(b) is a cross-sectional view taken along line 31AB-31AB in Figure 30, showing the locking member 99R in the unlocked position. Figure 32(a) is a cross-sectional view taken along line 32AB-32AB in Figure 30, showing the image forming apparatus 1 when the locking member 99R is in the locked position. Figure 32(b) is a cross-sectional view taken along line 32AB-32AB in Figure 30, showing the locking member 99R in the locked position.

[0133] The tip portion 99Rb and the abutting portion 99Rc are arranged offset from each other in the X direction, and the cross section 31AB-31AB in Fig. 30 is a cross section including the abutting portion 99Rc. The cross section 32AB-32AB in Fig. 30 is a cross section including the tip portion 99Rb.

[0134] As shown in Figures 31(a) and 31(b), when the rear cover 73 is in the open position, the locking member 99R is biased in the direction of arrow RD1 by its own weight. The locking member 99R biased in the direction of arrow RD1 is held in the unlocked position when the abutment portion 99Rc abuts against the stopper portion 7bR. In this embodiment, the stopper portion 7bR is provided in the transfer unit 7, but this is not limiting. For example, the stopper portion 7bR may be provided in the fixing unit 9 (see Figure 2) or another part of the apparatus main body 2.

[0135] Furthermore, when the locking member 99R is located in the unlocked position, the contact portion 99Ra of the locking member 99R is not engaged with the contacted portion 9Ra provided on the fixing unit 9. Here, the contacted portion 9Ra is provided in the space 77 surrounded by the U-shaped member into which the locking member 99R is inserted, as shown in Figures 29(c) and 29(d). Therefore, the transfer unit 7 provided with the locking member 99R is not locked to the device main body 2 including the contacted portion 9Ra, and the user can open and close the transfer unit 7.

[0136] Next, as shown in FIGS. 32(a) and 32(b), when the rear cover 73 is in the closed position, the locking member 99R is in the locked position. At this time, the contact portion 99Ra of the locking member 99R engages with the contacted portion 9Ra provided on the fixing unit 9. The contact portion 99Ra, serving as a first engagement portion, is formed in an arc shape centered on the lock shaft 7aR, and the contacted portion 9Ra, serving as a second engagement portion, is formed so that its tip tapers toward the contact portion 99Ra. As shown in FIG. 32(b), the contact portion 99Ra that has come into contact with (engaged with) the contacted portion 9Ra receives a reaction force F1, serving as a third reaction force, from the contacted portion 9Ra. The reaction force F1 is a force in the Y direction starting from the lock shaft 7aR and acts as a force in a direction to close the transfer unit 7 toward the closed position.

[0137] The locking member 99R is held in the locked position by the frictional force between the contacted portion 9Ra and the contacting portion 99Ra caused by this reaction force F1 and by the fact that a pressed portion 99Rb1 (described later) is pressed by the pressing portion 73h of the rear cover 73. The transfer unit 7 provided with the locking member 99R is locked to the device main body 2 including the contacted portion 9Ra by the contacting portion 99Ra of the locking member 99R engaging with the contacted portion 9Ra, and is held in the closed position. Furthermore, the transfer unit 7 is more stably held in the closed position because the contacting portion 99Ra attempts to rotate in the closing direction when it receives the reaction force F1.

[0138] In the present embodiment, the contact portion 99Ra and the contacted portion 9Ra are arranged to contact and engage with each other when the locking member 99R is in the locked position, but this is not limiting. For example, there may be a slight gap between the contact portion 99Ra and the contacted portion 9Ra, and the contact portion 99Ra and the contacted portion 9Ra may engage with each other only when the transfer unit 7 receives a reaction force F4 from the recording material P, as shown in FIG. 35 (described later). This restricts the transfer unit 7 from pivoting in the opening direction when the transfer unit 7 receives the reaction force F4 from the recording material P.

[0139] The tip end 99Rb of the locking member 99R has a pressed portion 99Rb1 that faces the pressing portion 73h provided on the inner surface 73f of the rear cover 73, and an inclined surface 99Rb2 that is provided on the opposite side in the direction of arrow RD1 from the pressed portion 99Rb1. The inclined surface 99Rb2 is formed to extend downstream in the direction of arrow RD2 as it moves radially inward of the locking member 99R.

[0140] The locking member 99R, which is located in the unlocked position, rotates toward the locked position when the pressed portion 99Rb1 is pressed by the pressing portion 73h of the rear cover 73. That is, the locking member 99R rotates from the unlocked position to the locked position in conjunction with the closing operation of the rear cover 73. In addition, the pressing portion 73h, which serves as a second moving portion, moves the locking member 99R from the unlocked position to the locked position.

[0141] 32(b) and 33, the rear cover 73 is provided with an unlocking claw 73i. The unlocking claw 73i is located downstream of the pressing portion 73h in the closing direction of the rear cover 73. For the sake of explanation, only the rear cover 73 and the locking member 99 are shown in FIG.

[0142] As shown in Figures 34(a) and 34(b), when the rear cover 73 is opened and closed between the open position and the closed position, the movement path of the unlocking claw 73i does not overlap with the locking member 99R located in the unlocked position, but overlaps with the locking member 99R located in the locked position. Therefore, for example, if the recording material P jams in the conveying path 19 (see Figure 35) and the rear cover 73 is opened from the closed position to the open position, the unlocking claw 73i provided on the rear cover 73 comes into contact with the inclined surface 99Rb2 of the locking member 99R. Then, as the rear cover 73 is further opened, the unlocking claw 73i presses the inclined surface 99Rb2, and the locking member 99R rotates in the direction of arrow RD1. In other words, the unlocking claw 73i as the first moving part moves the locking member 99R from the locked position to the unlocked position.

[0143] When the locking member 99R rotates in the direction of arrow RD1, the engagement between the abutted portion 9Ra and the abutting portion 99Ra is released, and the locking member 99 moves to the unlocked position shown in FIG. 31(b) by its own weight. In this manner, in this embodiment, the locking member 99R moves from the locked position to the unlocked position simply by the user opening the rear cover 73, allowing the user to quickly open the transfer unit 7 and improving usability. Furthermore, the inclined surface 99Rb2 is inclined in the direction of arrow RD1 about the lock shaft 7aR, and therefore can smoothly come into contact with the unlocking claw 73i.

[0144] Furthermore, because the unlocking claw 73i does not interfere with the locking member 99R that is in the unlocked position, when the rear cover 73 is closed from the open position to the closed position, it does not come into contact with the locking member 99R that is in the unlocked position. The locking member 99R is rotated from the unlocked position to the locked position by a pressing portion 73h that is provided on the rear cover 73. The pressing portion 73h is formed longer in the Z direction than the unlocking claw 73i. Therefore, while the unlocking claw 73i does not come into contact with the locking member 99R that is in the unlocked position, the pressing portion 73h can press the locking member 99R that is in the unlocked position.

[0145] In the present embodiment, the movement locus of the unlocking claw 73i is configured so as not to overlap the locking member 99R positioned at the unlock position, but to overlap the locking member 99R positioned at the locked position. However, this is not limited to this. For example, the movement locus of the unlocking claw 73i may be configured so as to overlap the locking member 99R positioned at both the unlocked and locked positions. In this case, the locking member 99R positioned at the unlocking position may come into contact with the unlocking claw 73i, but at least one of the unlocking claw 73i and the locking member 99R may be elastically deformed so that the unlocking claw 73i can pass through the locking member 99R.

[0146] Next, the necessity of the lock member 99R (99L) will be explained. As described above, the links 96L, 96R hold the transfer unit 7 in the closed position by the biasing force F2 of the tension springs 98L, 98R (see FIG. 28(a)). The biasing force F2 of the tension springs 98L, 98R is greater than the reaction force F3 that the transfer roller 7a receives from the photosensitive drum 11 (hereinafter simply referred to as the reaction force F3 of the transfer roller 7a). In other words, the reaction force F3 as a first reaction force is a reaction force that the transfer unit 7 receives from the apparatus main body 2 including the photosensitive drum 11.

[0147] Here, in the present embodiment, as shown in FIG. 35, the transfer unit 7 is provided with a protruding portion 7e. The protruding portion 7e as the abutting portion is provided adjacent to the transfer nip N1 at a position upstream of the transfer nip N1 in the recording material conveyance direction CD. When the recording material P is conveyed through the conveyance path 19, the protruding portion 7e is pressed by the recording material P. At this time, the force received by the protruding portion 7e from the recording material P is referred to as a reaction force F4 as the second reaction force from the recording material P. Thereby, the transfer unit 7 is biased in the opening direction. The protruding portion 7e has a function of correcting the posture of the recording material P so that the recording material P wraps around the photosensitive drum 11 at a larger angle, and the stability of image transfer at the transfer nip N1 is achieved. That is, the protruding portion 7e curves the recording material P toward the photosensitive drum 11.

[0148] The biasing forces F2 of the tension springs 98L and 98R are larger than the reaction force F3 of the transfer roller 7a, but are set to be smaller than the sum of the reaction force F3 of the transfer roller 7a and the reaction force F4 from the recording material P. In the present embodiment, for example, in a recording material having a higher rigidity than plain paper with a basis weight of 60 to 90 (g / m 2 ), the relationship of F3 < F2 < (F3 + F4) holds. For example, when an A4-sized cardboard with a basis weight of 91 to 199 (g / m 2 ) is applied to the recording material P, the relationship of F3 < F2 < (F3 + F4) holds. Also, the biasing force F2 acts as a force in the closing direction toward the closed position of the transfer unit 7, and the reaction forces F3 and F4 act as forces in the opening direction toward the open position of the transfer unit 7. Therefore, relying only on the biasing force F2 of the tension springs 98L and 98R, the transfer unit 7 rotates in the opening direction from the closed position when the recording material P is conveyed through the conveyance path 19. As a result, image formation at the transfer nip N1 and conveyance of the recording material P become unstable.

[0149] Therefore, in this embodiment, the transfer unit 7 is held in the closed position by the locking members 99L and 99R. This allows stable image formation and stable transport of the recording material P even when the recording material P is transported through the transport path 19. Furthermore, if the urging force F2 of the tension springs 98L and 98R were set to be greater than the sum of the reaction force F3 of the transfer roller 7a and the reaction force F4 from the recording material P, the operating force required by the user to open the transfer unit 7 would be large. In other words, by providing the locking members 99L and 99R, the urging force F2 of the tension springs 98L and 98R that urge the transfer unit 7 in the closing direction can be set to be small, thereby reducing the operating force required to open the transfer unit 7. This improves usability.

[0150] Consider a case where the tension springs 98L, 98R are not provided or where the biasing force F2 of the tension springs 98L, 98R is smaller than the reaction force F3 of the transfer roller 7a. In this case, when the rear cover 73 is opened, the transfer unit 7 is biased from the closed position toward the open position by the reaction force F3, which may cause the transfer unit 7 to open forcefully to the open position. Because the transfer unit 7 is relatively heavy, if the transfer unit 7 is opened forcefully to the open position, the rotation shaft 7c and the links 96L, 96R of the transfer unit 7 may be damaged. Therefore, by setting the biasing force F2 of the tension springs 98L, 98R to be larger than the reaction force F3 of the transfer roller 7a, as in this embodiment, the transfer unit 7 can be prevented from opening when the rear cover 73 is opened. This reduces damage to the transfer unit 7 and its supporting structure.

[0151] <Second embodiment> Next, a second embodiment of the present invention will be described. In the second embodiment, the present invention is applied to an image forming apparatus 300 having a different configuration from the image forming apparatus 1 of the first embodiment. Note that configurations similar to those of the first embodiment will be omitted from the illustrations or will be described with the same reference numerals in the drawings.

[0152] As shown in Fig. 36, the image forming apparatus 1 has a conveying path 319 that is a reversed S-shape. The image forming apparatus 1 has an image forming unit 20, a process unit 40, a fixing unit 9, a pair of discharge rollers 10, an open / close member 301, a locking member 304, and a cover member 306. The transfer roller 7a is urged in the Z direction toward the photosensitive drum 11 by an urging member (not shown), and the process unit 40 is urged in the negative Z direction by an urging member 303. The urging force of the urging member 303 is sufficiently greater than the urging force (not shown) that urges the transfer roller 7a, so the process unit 40 is positioned in the Z direction.

[0153] The opening / closing member 301 serving as an opening / closing unit is provided so as to be able to open and close about a pivot shaft 301a between a closed position serving as a first closed position where the opening / closing member 301 is closed relative to the apparatus main body 2, and a closed position serving as a first open position where the opening / closing member 301 is open relative to the apparatus main body 2. The biasing member 303 is provided between the opening / closing member 301 and the process unit 40. Therefore, the opening / closing member 301 is biased in the opening direction by a reaction force F5 from the biasing member 303 serving as a unit biasing unit. In other words, the reaction force F5 as the first reaction force is a reaction force that the opening / closing member 301 receives from the apparatus main body 2 including the process unit 40 and the biasing member 303. Meanwhile, the opening / closing member 301 is biased in the closing direction by a biasing force F6 that is greater than the reaction force from the biasing member 303, by a torsion coil spring 302 serving as a biasing unit.

[0154] Here, the contact portion 301e of the open / close member 301 is provided upstream of the transfer nip N1 in the recording material conveying direction CD, and receives a reaction force F7 as a second reaction force from the recording material P when the recording material P is conveyed through the conveying path 319. This is because the conveying roller pair 5c conveys the recording material P at a faster speed than the photosensitive drum 11, and as a result, a loop (flexure) is formed in the recording material P between the conveying roller pair 5c and the photosensitive drum 11. This loop of the recording material P causes the recording material P to wrap around the photosensitive drum 11 at a larger angle, stabilizing the transfer of the image at the transfer nip N1.

[0155] In this embodiment, the biasing force F6 of the torsion coil spring 302 is set to be smaller than the sum of the reaction force F5 of the biasing member 303 and the reaction force F7 of the recording material P. The biasing force F26 acts as a force in a direction to close the opening / closing member 301 toward the closed position, and the reaction forces F5 and F7 act as forces in a direction to open the opening / closing member 301 toward the open position. For this reason, if only the biasing force F6 of the torsion coil spring 302 were to be relied upon, the opening / closing member 301 would rotate from the closed position toward the open direction when the recording material P is transported through the transport path 319.

[0156] Therefore, in this embodiment, the opening / closing member 301 is held in the closed position by the locking member 304. This allows stable image formation and stable transport of the recording material P even when the recording material P is being transported through the transport path 319.

[0157] The locking member 304 has a hook portion 304b that can be engaged with an abutment portion 305 fixed to the device body 2, and is supported by the opening / closing member 301 so as to be rotatable about a rotation shaft 304a. The locking member 304 is biased counterclockwise in Figures 36 to 39 about the rotation shaft 304a by, for example, a biasing member (not shown) or its own weight. In other words, the locking member 304 is biased toward the unlock position.

[0158] Furthermore, cover member 306 as a cover portion has pressing portion 306a and unlocking claw 306b. Cover member 306 is supported so as to be openable and closable about pivot shaft 306c between a closed position as a second closed position where it is closed relative to device main body 2, and a second open position where it is open relative to device main body 2. Furthermore, cover member 306 covers opening / closing member 301 and transport path 319 in the closed position.

[0159] When cover member 306 is closed from the open position to the closed position, as shown in Fig. 36, pressing portion 306a, which serves as a second moving portion provided on cover member 306, rotates lock member 304 from the unlocked position to the locked position. When cover member 306 is in the closed position, lock member 304 is pressed by pressing portion 306a and held in the locked position. When lock member 304 is in the locked position, hook portion 304b is engaged with abutment portion 305, thereby locking open / close member 301 in the closed position.

[0160] 37 and 38, when a user opens the cover member 306 from the closed position to the open position around the rotation shaft 306c, the unlocking claw 306b serving as a first moving part rotates the locking member 304 from the locked position to the unlocked position. When the locking member 304 is in the unlocked position shown in FIG. 37, the hook portion 304b is not engaged with the abutment portion 305. Therefore, the opening / closing member 301 can be opened from the closed position to the open position around the rotation shaft 301a.

[0161] 38, the user can access and clear the jammed recording material P in the conveying path 319. Furthermore, as shown in FIG. 39, when the user opens the opening / closing member 301 around the rotation shaft 301a from the closed position to the open position, the user can remove and replace the process unit 40. In other words, the process unit 40 is detachable from the apparatus main body 2.

[0162] As described above, in this embodiment, the locking member 304 holds the opening / closing member 301 in the closed position. This allows stable image formation and stable conveyance of the recording material P even when the recording material P is being conveyed through the conveyance path 319. Furthermore, if the biasing force F6 of the torsion coil spring 302 were set to be greater than the sum of the reaction force F5 of the biasing member 303 and the reaction force F7 of the recording material P, the operating force required for the user to open the opening / closing member 301 would be large. In other words, by providing the locking member 304, the biasing force of the torsion coil spring 302 that biases the opening / closing member 301 in the closing direction can be set to be small, thereby reducing the operating force required to open the opening / closing member 301. This improves usability.

[0163] <Other embodiments> In the first embodiment, the contact portion 99Ra has an arc shape centered on the lock shaft 7aR, but this is not limited to this. For example, the contact portion 99Ra may be formed in an arc shape such that the radius between the contact portion 99Ra and the lock shaft 7aR decreases as the contact portion 99Ra moves downstream in the direction of arrow RD2. This allows the contact portion 99Ra and the contacted portion 99Ra of the lock member 99R to engage with stronger force in the locked position, thereby reliably locking the transfer unit 7 in the closed position.

[0164] In the first embodiment, the protrusion 7e is provided on the transfer unit 7, but this is not limiting. For example, the protrusion 7e may be provided on a transport guide that faces the transfer unit 7 and constitutes the transport path 19.

[0165] Furthermore, in the second embodiment, torsion coil spring 302 is used, but this is not limiting. For example, instead of torsion coil spring 302, other springs such as a leaf spring or a torsion bar may be used.

[0166] Furthermore, although the locking members 99L, 99R in the first embodiment are provided in the transfer unit 7, this is not limiting. For example, the locking members 99L, 99R may be provided in the device body 2 instead of the transfer unit 7. That is, the locking members 99L, 99R as locking sections may be provided in either the transfer unit 7 or the device body 2. In any case, it is sufficient that the locking members 99L, 99R can lock the transfer unit 7, which is located in the closed position, to the device body 2 when the rear cover 73 is located in the closed position.

[0167] Furthermore, although the locking member 304 in the second embodiment is provided on the opening / closing member 301, this is not limiting. For example, the locking member 304 may be provided on the device body 2 instead of the opening / closing member 301. That is, the locking member 304 as a locking section may be provided on either the opening / closing member 301 or the device body 2. In any case, it is sufficient that the locking member 304 can lock the opening / closing member 301, which is located in the closed position, to the device body 2 when the cover member 306 is located in the closed position.

[0168] In addition, although the above-described embodiments have been described using the electrophotographic image forming apparatus 1300, the present invention is not limited to this. For example, the present invention can also be applied to an inkjet image forming apparatus that forms an image on a recording material by ejecting ink liquid from nozzles.

[0169] The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program. It can also be realized by a circuit (e.g., ASIC) that realizes one or more functions. [Explanation of symbols]

[0170] 1,300: Image forming apparatus / 2: Device body / 5c: Transport unit (pair of transport rollers) / 7: Opening / closing unit, transfer unit / 7a: Transfer member (transfer roller) / 7e: Protrusion / 9Ra: Second engagement portion (contact portion) / 11: Image carrier (photosensitive drum) / 18: Toner storage portion (storage portion) / 19,319: Transport path / 40: Process unit / 72: Housing / 73: Cover portion (rear cover) / 73h, 306a: Second moving portion (pressing portion) / 73i, 306b: First moving portion (unlocking claw) / 98L , 98R: urging portion (tension spring) / 99L, 99R, 304: lock portion (lock member) / 99Ra: first engagement portion (contact portion) / 303: unit urging portion (urging member) / 200: supply portion / 301: opening / closing portion (opening / closing member) / 302: urging portion (torsion coil spring) / 306: cover portion (cover member) / CD: recording material conveyance direction / F1: third reaction force (reaction force) / F2, F6: urging force / F3, F5: first reaction force (reaction force) / F4, F7: second reaction force (reaction force) / P: recording material / N1: transfer nip

Claims

1. An image forming apparatus capable of forming an image on a recording material having a basis weight equal to or greater than a predetermined value, an apparatus body having a rotatable image carrier; a transfer member that forms a transfer nip together with the image carrier and transfers the image formed on the image carrier to the recording material; a protrusion provided adjacent to the transfer nip at a position upstream of the transfer nip in a conveyance direction of the recording material, the protrusion curving the recording material toward the image carrier; an opening / closing unit that is openable and closable between a first closed position that is closed relative to the device body and a first open position that is open relative to the device body; a biasing portion that biases the opening / closing portion toward the first closed position; a locking section provided on either the opening / closing section or the device body, the locking section being movable between a locked position where the opening / closing section is locked to the device body when the opening / closing section is in the first closed position, and an unlocked position where the opening / closing section is released from the device body; a cover portion that is provided so as to be openable and closable between a second closed position in which the cover portion is closed relative to the device body and a second open position in which the cover portion is open relative to the device body, and that covers the open / close portion that is located at the first closed position when in the second closed position; the locking portion is located at the locking position when the cover portion is located at the second closed position, the biasing force of the biasing portion is greater than a first reaction force that the opening / closing portion receives from the apparatus main body and is smaller than a sum of a second reaction force that the opening / closing portion receives from the recording material being transported in the transport direction and the first reaction force; An image forming apparatus characterized by:

2. The first reaction force and the second reaction force act as forces in a direction to open the opening / closing unit toward the first open position.

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

3. the protrusion is provided on the opening / closing portion and configured to come into contact with the recording material being transported in the transport direction and receive the second reaction force.

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

4. the locking portion is biased toward the unlocked position and is positioned at the unlocked position when the cover portion is positioned at the second open position; 4. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

5. the cover portion has a first moving portion that moves the lock portion from the lock position to the unlock position when the cover portion is opened from the second closed position to the second open position.

5. The image forming apparatus according to claim 4.

6. the cover portion has a second moving portion that moves the lock portion from the unlock position to the lock position when the cover portion is closed from the second open position to the second closed position.

6. The image forming apparatus according to claim 5,

7. the apparatus main body includes a process unit having the image carrier and a toner storage section that stores toner; the opening / closing unit is a transfer unit having the transfer member that forms the transfer nip together with the image carrier when the opening / closing unit is located at the first closed position, the first reaction force is a reaction force that the transfer member receives from the image carrier; 7. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

8. the locking portion has a first engaging portion and is provided on the transfer unit; the apparatus main body has a second engaging portion that can engage with the first engaging portion when the transfer unit is in the first closed position and the locking portion is in the locking position; 8. The image forming apparatus according to claim 7,

9. the locking portion is rotatable about a rotation axis between the locked position and the unlocked position, the first engagement portion is formed in an arc shape centered on the rotation axis, and receives a third reaction force from the second engagement portion when the first engagement portion is engaged with the second engagement portion; The third reaction force acts as a force in a direction to close the opening / closing unit toward the first closed position.

9. The image forming apparatus according to claim 8,

10. the process unit has a supply section that is in communication with the toner storage section and that receives toner supplied from an external source while the process unit is attached to the apparatus main body; 10. The image forming apparatus according to claim 7, wherein the image forming apparatus is a recording medium.

11. The apparatus main body includes a process unit having the image carrier and a toner storage unit that stores toner; a unit biasing section that is provided between the process unit and the opening / closing section that is positioned at the first closed position and that biases the image carrier toward the transfer member that is provided in the apparatus main body, the first reaction force is a reaction force that the opening / closing portion receives from the unit biasing portion; 7. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

12. The locking portion is provided on the opening / closing portion.

12. The image forming apparatus according to claim 11.

13. the process unit is detachable from the housing of the apparatus main body when the cover is located at the second open position and the opening / closing unit is located at the first open position; 13. The image forming apparatus according to claim 7, wherein the image forming apparatus is a recording medium.

Images