Developing device

Abstract

A developing device includes a developing roller, a supply roller, and a developing container. The developing container includes a developing chamber, a developer accommodating chamber having an opening and an inner wall surface, a conveying member having a rotation axis, and a detection portion. In a cross section perpendicular to the rotation axis, the detection portion is provided in a region of the inner wall surface positioned between a first point, which is a downstream end of the opening with respect to a rotation direction, and a second point, which is a downstream end of the opening with respect to the rotation direction, with respect to the rotation direction of the conveying member. The second point is a point at which an imaginary line passing through the rotation axis and an upstream end of the opening with respect to the rotation direction intersects the inner wall surface.

Description

Technical Field

[0001] The present invention relates to a developing device for an image forming apparatus using an electrophotographic type or an electrostatic recording type, the image forming apparatus being, for example, a copying machine, a printer, a facsimile machine, or a multifunction machine having a plurality of functions among these machines. Background Art

[0002] Conventionally, for example, an image forming apparatus using an electrophotographic type (such as a printer) includes a developing device for developing an electrostatic latent image formed on an image bearing member using a developer. The developing device is manufactured so as to be detachably mounted to the main assembly of the image forming apparatus substantially alone, or so as to be detachably mounted to the main assembly of the image forming apparatus in combination with other components as a process cartridge.

[0003] The developing device includes a developing chamber in which a developing member, etc., for supplying developer to an image bearing member is disposed, and a developer accommodating chamber (hereinafter also referred to simply as a "accommodating chamber") in which the developer supplied to the developing chamber is accommodated. The developing chamber and the accommodating chamber are separated by a partition wall, and the developer is supplied from the accommodating chamber to the developing chamber through a supply opening provided in the partition wall. In many cases, a rotatable conveying member for conveying the developer is disposed in the accommodating chamber.

[0004] Furthermore, the developing device may be provided with a remaining amount detecting portion for detecting the remaining amount of developer in the developing device as the developer decreases with image formation. The imaging apparatus can notify the user of the detected remaining amount of developer in the developing device (or the amount of developer consumed).

[0005] In a conventional configuration, a remaining amount detection portion is provided in the accommodating chamber, and the remaining amount of developer in the developing device is detected. Therefore, when the remaining amount detection portion is provided in the accommodating chamber, based on the amount of developer detected in the accommodating chamber, a "total remaining amount of developer" is calculated as the remaining amount of developer in the developing device. This "total remaining amount of developer" is the sum of the "amount of developer in the accommodating chamber" and the "amount of developer in the developing chamber." Summary of the Invention

[0006] According to one aspect of the present invention, a developing device for forming an image in an imaging device is provided, comprising: a developing roller configured to carry a developer; a supply roller configured to contact the developing roller and supply the developer to the developing roller; and a developing container, the developing roller being rotatably supported by the developing container, the developing container comprising: a developing chamber provided with the supply roller; a developer accommodating chamber separated from the developing chamber by a partition wall provided with an opening and configured to accommodate the developer, the developer accommodating chamber being connected to the developing chamber through the opening, and being positioned above the developing chamber when the developing device takes a posture in which the developing device is used for forming an image; a conveying member provided in the developer accommodating chamber and It is configured to convey the developer from the developer accommodating chamber toward the developing chamber through the opening, the conveying member being rotatable around its rotation axis in a rotation direction opposite to the rotation direction of the supply roller; and a detection portion, which is configured to output a signal according to the amount of developer accommodated in the developing chamber, the detection portion being arranged on the inner wall surface constituting the developer accommodating chamber, wherein, in a cross section perpendicular to the rotation axis, the detection portion is arranged in an area of ​​the inner wall surface between a first point and a second point relative to the rotation direction of the conveying member, the first point being the downstream end of the opening relative to the rotation direction, and the second point being a point at which a virtual line passing through the rotation axis and the upstream end of the opening relative to the rotation direction intersects the inner wall surface.

[0007] Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a schematic cross-sectional view of an imaging apparatus.

[0009] Figure 2 is a schematic cross-sectional view of the image forming apparatus in a state where the front door is open.

[0010] Figure 3 is a schematic cross-sectional view of the image forming apparatus in a state where the cartridge tray is pulled out.

[0011] Figure 4 is a schematic sectional view of the image forming apparatus in a state where the process cartridge is removed.

[0012] Figure 5 is a cross-sectional view of the process cartridge.

[0013] Figure 6 This is an exploded perspective view of the drum unit.

[0014] Figure 7 This is an exploded perspective view of the developing unit.

[0015] Figure 8 It is a three-dimensional diagram of the assembly of the process cartridge.

[0016] Figure 9 It is a perspective view of a process cartridge.

[0017] Figure 10 is a schematic perspective view of a developing unit.

[0018] Figure 11 is a schematic cross-sectional view of a developing unit.

[0019] Figure 12 It is a schematic perspective view of the second developing (device) frame.

[0020] Figure 13 Parts (a) and (b) are a schematic front view and a schematic side view of the second developing frame, respectively.

[0021] Figure 14 This is a schematic diagram of the developer remaining amount detection structure.

[0022] Figure 15 Parts (a) and (b) are schematic cross-sectional views of the developing unit for illustrating the conveyance of the developer toward the remaining amount detecting portion.

[0023] Figure 16 Parts (a) and (b) are schematic cross-sectional views of the vicinity of the developing chamber for illustrating the problem.

[0024] Figure 17 is a schematic cross-sectional view of a developing unit for illustrating the effects of the embodiment. DETAILED DESCRIPTION

[0025] Hereinafter, embodiments of the developing device according to the present invention will be described in detail with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the constituent parts described in the following embodiments should be appropriately changed according to the configuration and various conditions of the device (apparatus) to which the present invention is applied, and the scope of the present invention is not limited to the following embodiments.

[0026] [Example 1]

[0027] <General Structure and Operation of Imaging Equipment>

[0028] First, refer to Figure 1 The general structure and operation of the imaging apparatus in this embodiment are described. Figure 1is a schematic cross-sectional view of the imaging apparatus of this embodiment. The imaging apparatus 100 in this embodiment is a tandem laser beam printer capable of forming full-color images on sheet-like recording material P using electrophotography and employing an intermediate transfer method. Furthermore, the imaging apparatus 1 in this embodiment employs a process cartridge type, wherein the process cartridges 100 (100Y, 100M, 100C, 100K) are removably attached to the apparatus main assembly 2 of the imaging apparatus 1 and perform image formation. In this embodiment, the apparatus main assembly 2 of the imaging apparatus 1 is the portion of the imaging apparatus 1 excluding the process cartridges 100 (100Y, 100M, 100C, 100K). Incidentally, while the recording material P is sometimes referred to as paper, the recording material P may include materials other than paper or may be formed from materials other than paper (such as synthetic paper or film formed from synthetic resin, metallized paper including a metal layer, etc.).

[0029] Here, regarding the imaging device 1 and its elements, Figure 1 The right (hand) side in FIG. 1 (on which a front door 10 described later is located) is referred to as the "front (front surface) side", Figure 1 , the left (hand) side (the side opposite to the front side) in is referred to as the "rear (back) surface side". Further, with respect to the imaging device 1 and its elements, in the case of observing the imaging device 1 from the front side, the right side is the "drive side" and the left side is the "non-drive side". The drive side is the side on which a drum coupling member for inputting a driving force to the photosensitive drum 101 described later and a developing coupling member for inputting a driving force to the developing roller 103 described later are provided. Further, with respect to the imaging device 1 and its elements, "up (above)" and "down (below)" refer to "up (above)" and "down (below)" relative to the direction of gravity (vertical direction), respectively, but are not intended to mean only "directly up (above)" and "directly down (below)", respectively, and include "upper side" and "lower side", respectively, relative to a horizontal surface passing through the relevant elements or positions. Further, Figure 1 The left-right direction connecting the front and rear sides is the "X direction", which connects the non-drive side and the drive side and is connected to the Figure 1The direction perpendicular to the drawing is the "Y direction", and the direction perpendicular to the X and Y directions is the "Z direction". The imaging device 100 is arranged so that the Z direction is roughly parallel to the direction of gravity (so that each of the X and Y directions is roughly parallel to the horizontal direction) and is used for imaging. Furthermore, the Y direction is roughly parallel to the direction of the rotation axis of the photosensitive drum 101 and the developing roller 103. In the X direction, the direction from the front side toward the rear side is the "X1 direction", and the direction from the rear side toward the front side is the "X2 direction". In the Z direction, the direction from the lower side toward the upper side is the "Z1 direction", and the direction from the upper side toward the lower side is the "Z2 direction". That is, the imaging device 1 is arranged so that the Z2 direction becomes the direction of gravity. Furthermore, in the Y direction, the direction from the non-driven side toward the driven side is the "Y1 direction", and the direction from the driven side toward the non-driven side is the "Y2 direction". Figure 1 : is a schematic cross-sectional view of the imaging apparatus 1 , showing a state in which a cross section (XZ plane) substantially perpendicular to the Y direction is viewed from the non-driving side, wherein the front side of the drawing is the non-driving side and the rear side of the drawing is the driving side.

[0030] The imaging device 1 includes four imaging units 3Y, 3M, 3C, and 3K, serving as a plurality of imaging units (stations), for forming images in yellow (Y), magenta (M), cyan (C), and black (K), respectively. The four imaging units 3Y, 3M, 3C, and 3K are arranged in series along the direction of movement of the image transfer surface of the intermediate transfer belt 51, described later. In this embodiment, this arrangement is horizontal, but when the imaging device 1 is mounted on a horizontal surface, it is slightly tilted relative to the horizontal direction. Incidentally, in some cases, elements having the same or corresponding functions or configurations provided for each color are collectively described by omitting the suffixes Y, M, C, and K in the reference numerals or symbols, each suffix indicating a component specific to one of the colors. In this embodiment, the image forming section 3 is configured by including the photosensitive drums 101 (101Y, 101M, 101C, 101K), charging rollers 102 (102Y, 102M, 102C, 102K), a laser scanner unit (exposure device) 11, a developing unit (developing device) 140, and the like. In this embodiment, the laser scanner unit 11 is configured as a single unit for exposing the four photosensitive drums 101Y, 101M, 101C, and 101K, but may be provided independently of each other for the respective photosensitive drums 101.

[0031] The photosensitive drum 101 is moved along the Figure 1The photosensitive drum 101 is a rotatable drum-shaped (cylindrical) photosensitive member (electrophotographic member) serving as an image bearing member, and is rotationally driven in the direction indicated by arrow R1 (clockwise). The surface (peripheral surface) of the rotating photosensitive drum 101 is uniformly charged to a predetermined potential of a predetermined polarity (negative in this embodiment) by a charging roller 102, a roller-shaped charging member serving as a charging device. The charging roller 102 is positioned in contact with the surface of the photosensitive drum 101 and rotates as the photosensitive drum 101 rotates. During charging, a predetermined charging bias (charging voltage) is applied to the charging roller 102 by a charging power supply (not shown), serving as a charging voltage application unit. This charging bias is a DC voltage having the same polarity as the charge polarity of the photosensitive drum 101 (negative in this embodiment). The laser scanner unit 11 exposes the charged surface of the photosensitive drum 101 to laser light 12 for scanning exposure based on an image signal corresponding to a color component in the imaging unit 3. Thus, on the photosensitive drum 101 , an electrostatic latent image (electrostatic image) is formed according to the image signal of the color component corresponding to the relevant image forming portion 3 .

[0032] The electrostatic latent image formed on the photosensitive drum 101 is developed (visualized) by a developer (hereinafter also referred to as "toner") supplied by a developing unit 140, serving as a developing device. This results in a toner image (toner picture, developer image) being formed on the photosensitive drum 101. In this embodiment, the developing unit 140 uses a non-magnetic, single-component developer (toner) as the developer. The developing unit 140 includes a developing roller 103, serving as a developer carrying member (developing member). While carrying the toner, the developing roller 103 conveys the toner toward the developing section, which is the opposing section (contact section) with the photosensitive drum 101. During development, the developing roller 103 contacts the photosensitive drum 101. Furthermore, during development, the developing roller 103 is rotationally driven at a predetermined peripheral speed in a direction in which the surface movement direction of the photosensitive drum 101 and the surface (outer peripheral surface) movement direction of the developing roller 103 become the same (positive) direction within the developing section. Furthermore, during development, a predetermined development bias (development voltage) is applied to the developing roller 103 by a development power supply (not shown), serving as a development voltage application unit. This development bias is a DC voltage having the same polarity as the charge polarity of the photosensitive drum 101 (negative in this embodiment). Consequently, toner is supplied from the surface of the developing roller 103 to the surface of the photosensitive drum 101 in accordance with the electrostatic latent image on the photosensitive drum 101, thereby developing the electrostatic latent image on the photosensitive drum 101. In this embodiment, the toner, charged to the same polarity as the charge polarity of the photosensitive drum 101 (negative in this embodiment), deposits on the exposed portion (image portion) of the photosensitive drum 101 surface. This exposed portion, after being uniformly charged, has its absolute potential reduced by exposure (reverse development). In this embodiment, the normal charge polarity of the toner (which is the predominant charge polarity of the toner during development) is negative.

[0033] Below the four photoreceptor drums 101Y, 101M, 101C, and 101K, an intermediate transfer unit 5 is disposed opposite these drums. The intermediate transfer unit 5 includes an intermediate transfer belt 51, which is an endless belt serving as an intermediate transfer member; a drive roller 53 and a tension roller 52, each of which is a plurality of stretching rollers (support rollers); and four primary transfer rollers 54Y, 54M, 54C, and 54K. The flexible intermediate transfer belt 51 extends around the drive roller 53 and the tension roller 52 and is stretched with a predetermined tension. Furthermore, on the inner circumferential surface of the intermediate transfer belt 51, primary transfer rollers 54Y, 54M, 54C, and 54K, corresponding to the photoreceptor drums 101Y, 101M, 101C, and 101K, are disposed. These primary transfer rollers are roller-shaped primary transfer members serving as primary transfer devices. The primary transfer roller 54 presses the intermediate transfer belt 51 toward the associated photosensitive drum 101 and forms a primary transfer portion (primary transfer nip) N1 (N1Y, N1M, N1C, N1K), which is the contact portion between the photosensitive drum 101 and the intermediate transfer belt 51. In this embodiment, the photosensitive drum 101 contacts the upper surface of the intermediate transfer belt 51 at its lower surface. The contact portion is the primary transfer portion N1. The driving force is transmitted to the intermediate transfer belt 51 by rotationally driving the drive roller 53, so that the intermediate transfer belt 51 moves along the intermediate transfer belt 51. Figure 1 The intermediate transfer belt 51 rotates (circulates and moves) in the direction of arrow R2 (counterclockwise) in the figure. The tension roller 52 and the primary transfer roller 54 rotate as the intermediate transfer belt 51 rotates. The toner image formed on the photosensitive drum 101 is transferred (primarily transferred) to the rotating intermediate transfer belt 51 in the primary transfer section N1. During the primary transfer, a primary transfer bias (primary transfer voltage) is applied to the primary transfer roller 54. This primary transfer bias is a DC voltage with a polarity opposite to the normal charge polarity (positive polarity in this embodiment). For example, during full-color image formation, the toner images of yellow, magenta, cyan, and black formed on the photosensitive drum 101 are transferred to the intermediate transfer belt 51 in an overlapping manner in the imaging area.

[0034] Incidentally, when the image forming operation starts, the rotation drive of the photosensitive drum 101, the rotation drive of the intermediate transfer belt 51, and the driving of the laser scanner unit 11 are started. Then, in synchronization with the driving of the laser scanner unit 11, the charging roller 102 starts charging the surface of the photosensitive drum 101.

[0035] A secondary transfer roller 6, a roller-shaped secondary transfer member serving as a secondary transfer device, is provided on the outer peripheral surface of the belt, at a position opposing the drive roller 53. The secondary transfer roller 6 is pressed toward the drive roller 53 and contacts the drive roller 53 via the intermediate transfer belt 51, thereby forming a secondary transfer portion (secondary transfer nip) N2, which is the contact portion between the intermediate transfer belt 51 and the secondary transfer roller 6. The secondary transfer roller 6 rotates as the intermediate transfer belt 51 rotates. In the secondary transfer portion N2, the toner image formed on the intermediate transfer belt 51 is transferred (secondarily transferred) onto the recording material P, which is nipped and conveyed between the intermediate transfer belt 51 and the secondary transfer roller 6. During the secondary transfer, a predetermined secondary transfer bias (secondary transfer voltage) is applied to the secondary transfer roller 6. This secondary transfer bias is a DC voltage with a polarity opposite to the normal charge polarity of the toner (positive polarity in this embodiment). Recording material (recording medium, transfer material, sheet) P is supplied from a feed unit 4 disposed below the intermediate transfer unit 5 toward the secondary transfer section N2. The feed unit 4 comprises, for example, a sheet (paper) feed tray 41 in which recording material P (e.g., paper) is stacked and accommodated, and sheet feed rollers 42 serving as a feed member. At predetermined control timing, the recording materials P are separated and fed one by one from the sheet feed tray 41 by the sheet feed rollers 42, and the fed recording materials P are conveyed toward a registration roller pair 70 serving as a recording material conveying member. The recording materials P are conveyed toward the secondary transfer section N2 by the registration roller pair 70 at predetermined control timing.

[0036] The recording material P onto which the toner image is transferred is conveyed toward a fixing device 7 serving as a fixing means. The fixing device 7 fixes (melts, adheres) the toner image to the recording material P by heating and pressing the recording material P carrying the unfixed toner image thereon. The recording material P onto which the toner image is fixed is discharged (output) by a discharge roller pair 8 or the like serving as a discharge member onto a sheet discharge tray 9 serving as a discharge portion provided outside (in the upper portion) of the apparatus main assembly 2.

[0037] In this embodiment, in each of the imaging units 3, a photosensitive drum 101, a charging roller 102 as a processing device that acts on the photosensitive drum, and a developing unit 140 integrally constitute a process cartridge 100 that is removably mounted to the apparatus main assembly 2. In this embodiment, four process cartridges 100Y, 100M, 100C, and 100K are removably mounted to the apparatus main assembly 2. The four process cartridges 100Y, 100M, 100C, and 100K perform the same electrophotographic process and differ from one another in the color of the toner used. Furthermore, the toner filling amount can differ between at least two of the process cartridges 100. A rotational driving force is transmitted to the process cartridge 100 from a driving force output portion of the apparatus main assembly 2 (details of which will be described later) so that an electrical bias (charging bias, developing bias, remaining amount detection bias, etc.) is supplied from a controller (not shown) of the apparatus main assembly 2. Incidentally, the number of process cartridges detachably mountable to the apparatus main assembly of the image forming apparatus is not limited to four, but may be appropriately set as necessary.

[0038] <Process cartridge installation and removal mechanism>

[0039] Next, the mounting and removal of the process cartridge 100 relative to the apparatus main assembly 2 in this embodiment will be described.

[0040] like Figure 1 , the image forming apparatus 1 is provided with a movable cartridge tray 20 for supporting a process cartridge 100. In addition, the image forming apparatus 1 is provided with a front door 10 that is openable and closable to allow the process cartridge 100 to be mounted and removed relative to the apparatus main assembly 2. In the present embodiment, the front door 10 is rotatable about a rotation axis provided at its lower end portion and substantially parallel to the Y direction so that its upper end portion in a closed state is opened by moving downward, and the upper end portion is closed by moving upward.

[0041] Figure 2 is a schematic sectional view of the image forming apparatus 1 in a state in which the cartridge tray 20 is positioned inside the apparatus main assembly 2 . Figure 3 1 is a schematic sectional view of the image forming apparatus 1 in a state where the cartridge tray 20 is positioned outside the apparatus main assembly 2 and the process cartridges 100 are accommodated in the cartridge tray 20 .

[0042] further, Figure 4 1 is a schematic sectional view of the image forming apparatus 1 in a state in which the front door 10 is opened, the cartridge tray 20 is positioned outside the apparatus main assembly 2 , and the process cartridge 100Y for yellow is removed from the cartridge tray 20 . Figures 2 to 4 Each shows a state in which a cross section (XZ plane) substantially perpendicular to the Y direction is viewed from the non-driving side.

[0043] like Figure 2 and Figure 3 As shown in FIG, the cartridge tray 20 is movable in the direction of arrow X1 (push-in direction) and the direction of arrow X2 (pull-out direction). That is, the cartridge tray 20 is constructed so that in a state where the apparatus main assembly 2 is set on a horizontal surface, the cartridge tray 20 can be pulled out and pushed in relative to the apparatus main assembly 2 by moving in a substantially horizontal direction. Here, in a state where the front door 10 is open and the cartridge tray 20 is positioned outside the apparatus main assembly 2 ( Figure 3 ) is referred to as the "external state". Further, the state in which the front door 10 is open and the cartridge tray 20 is positioned inside the main assembly 2 of the apparatus is referred to as the "internal state". In the external state and the internal state, each of the photosensitive drums 101 and the intermediate transfer belt 51 are separated from each other. Incidentally, in the present embodiment, the intermediate transfer unit 5 can be moved together with the cartridge tray 20 in the direction of arrow X1 (pushing direction) and in the direction of arrow X2 (pulling direction). Further, in the present embodiment, the imaging apparatus 1 is constructed so that when the pulling-out operation and the pushing-in operation of the cartridge tray 20 (and the intermediate transfer unit 5) relative to the main assembly 2 of the apparatus are performed, the fixing device 7 can be moved in the direction of arrow Z1 (upward).

[0044] Further, if Figure 4 As shown in FIG, the cartridge tray 20 includes a mounting portion 21 to which each process cartridge 100 can be detachably mounted in an external state. Figure 4 , only the mounting portion 21 for the yellow process cartridge 100Y is shown, but the cartridge tray 20 similarly includes the mounting portions 21 for the other process cartridges 100M, 100C, and 100K.

[0045] Furthermore, with the process cartridge mounted on the mounting portion 21, the cartridge tray 20 is moved into the apparatus main assembly 2, thereby moving the process cartridge 100 into the apparatus main assembly 2. In this embodiment, by closing the front door 10, the intermediate transfer unit 5 is moved (raised) in the direction of arrow Z1 (upward) by a linkage mechanism (not shown). This moves the intermediate transfer unit 5 to a position during image formation (a position where the photosensitive drum 101 and the intermediate transfer belt 51 are in contact with each other). Furthermore, in this embodiment, by opening the front door 10, the intermediate transfer unit 5 is moved (lowered) in the direction of arrow Z2 (downward) by the linkage mechanism. This moves the intermediate transfer unit 5 to a position where the photosensitive drum 101 and the intermediate transfer belt 51 are separated from each other.

[0046] Therefore, the plurality of process cartridges 100 can be moved together to a position inside the apparatus main assembly 2 where an image can be formed and a position outside the apparatus main assembly 2 where each process cartridge 100 can be demounted (removed) by the cartridge tray 20 .

[0047] <General Structure of the Process Cartridge>

[0048] Next, a general structure of the process cartridge 100 in this embodiment will be described.

[0049] Figure 5 1 is a cross-sectional view of the process cartridge 100 , showing a state in which a cross section (XZ plane) substantially perpendicular to the Y direction of the process cartridge 100 is viewed from the non-driving side. Figure 6 This is an exploded perspective view of a drum unit 120, which will be described later and constitutes the process cartridge 100 ( Figure 6 Shows the state viewed from slightly above along the X1 direction, so that Figure 6 The left side is the non-drive side and the right side is the drive side). Figure 7 is an exploded perspective view of the developing unit 140 constituting the process cartridge 100 ( Figure 7 Shows the state viewed from slightly below along the X2 direction, so that Figure 7 The left side is the drive side and the right side is the non-drive side). Figure 8 is an assembly view of the process cartridge 100 ( Figure 8 Shows the state viewed from slightly above along the X2 direction, so that Figure 8 The left side is the drive side and the right side is the non-drive side). Figure 9 is a perspective view of the process cartridge 100 ( Figure 9 Shows the state viewed from slightly above along the X2 direction, so that Figure 9 The left side is the drive side and the right side is the non-drive side).

[0050] In this embodiment, the process cartridge 100 includes a drum unit 120 provided with a photosensitive drum 101 and a charging roller 102 as a charging device (which serves as a process device that can act on the photosensitive drum). Here, the drum unit 120 may include not only the charging device as a process device but also a cleaning device for cleaning the surface of the photosensitive drum 101 as a process device.

[0051] Furthermore, the process cartridge 100 includes a developing unit (developing device) 140, which is a processing device that can act on the photosensitive drum 101. This developing unit is a developing device for developing the electrostatic latent image on the photosensitive drum 101. The drum unit 120 and the developing unit 140 are connected to each other. The process cartridges 100Y, 100M, 100C, and 100K for yellow, magenta, cyan, and black, respectively, contain yellow, magenta, cyan, and black toners. In the main assembly 2 of the apparatus, a laser scanner unit 11 is provided above the four process cartridges 100Y, 100M, 100C, and 100K. This laser scanner unit 11 outputs laser light 12. The laser light 12 then passes through an exposure window 128 of the process cartridge 100, causing the surface of the photosensitive drum 101 to be scanned and exposed by the laser light 12. The specific structure of the process cartridge 100 will be described later.

[0052] Incidentally, regarding the process cartridge 100, the drum unit 120, the developing unit 140, or components of these components, the direction of the rotation axis A1 of the photosensitive drum 101 (see Figure 8 The direction approximately parallel to the Y direction is also referred to as the "longitudinal direction." The process cartridge 100 is configured such that the rotation axis A1 of the photosensitive drum 101 is arranged approximately parallel to the Y direction and is used for image formation. Therefore, the longitudinal direction is a direction approximately parallel to the Y direction.

[0053] <Structure of the drum unit>

[0054] like Figure 6 and Figure 8 As shown in FIG, the drum unit 120 is constituted by including a photosensitive drum 101, a charging roller 102, a drum frame 121, and the like. The charging roller 102 is rotatably supported at its opposite ends with respect to the longitudinal direction by a driving side charging bearing 126a and a non-driving side charging bearing 127a. The charging roller 102 is urged toward the photosensitive drum 101 ( Figure 5 The driving side charging roller bearing 126a and the pressing spring 126b constitute the driving side charging roller bearing unit 126. Furthermore, the non-driving side charging roller bearing 127a and the pressing spring 127b constitute the non-driving side charging roller bearing unit 127. Furthermore, for example, before starting to use a new process cartridge 100, separating members 129 and 130 for separating the charging roller 102 from the photosensitive drum 101 are respectively attached to opposite ends of the charging roller 102 with respect to the longitudinal direction.

[0055] The photosensitive drum 101 is rotatably supported at its opposite ends with respect to the longitudinal direction by a drive side cartridge cover member 122 and a non-drive side cartridge cover member 123. Each of the drive side cartridge cover member 122 and the non-drive side cartridge cover member 123 is fixed to the drum frame 121 by any fixing means such as bonding, welding or fastening.

[0056] like Figure 8 As shown in FIG, in the driving side end portion of the photosensitive drum 101 with respect to the longitudinal direction, a drum coupling member 125 is provided as a drive input portion for transmitting the driving force to the photosensitive drum 101. The drum coupling member 125 is connected to the main assembly side drum drive coupling 30 ( Figure 3 and Figure 4) is engaged. Further, the driving force from the driving motor (not shown) provided in the main assembly 2 of the apparatus is transmitted to the photosensitive drum 101 through the main assembly side drum driving coupling 30 and the drum coupling member 125 to rotate the photosensitive drum 101. Further, a drum flange 124 is provided in the non-driving side end portion of the photosensitive drum 101 with respect to the longitudinal direction. The photosensitive drum 101 is Figure 5 The charging roller 102 is driven to rotate in the direction of the arrow R1 (clockwise). As the photosensitive drum 101 rotates, the charging roller 102 moves along the Figure 5 101. The charging roller 102 rotates in the direction of arrow R6 (counterclockwise) in FIG. Each of the drive side charging bearing 126a and the non-drive side charging bearing 127a is supported by the drum frame 121 so as to be able to rotate as the photosensitive drum 101 rotates while in contact with the surface of the photosensitive drum 101. Each of the drive side charging bearing 126a and the non-drive side charging bearing 127a is supported by the drum frame 121 so as to be able to move toward and away from the photosensitive drum 101 through contact between the charging roller 102 and the photosensitive drum 101. Further, the photosensitive drum 101 is supported by the drum frame 121, wherein the drum coupling member 125 and the drum flange 124 are rotatably supported by the drive side cartridge cover member 122 and the non-drive side cartridge cover member 123, respectively.

[0057] <Structure of the developer unit>

[0058] like Figure 5 and Figure 7 As shown in FIG, the developing unit 140 includes a developing roller 103, a supply roller 104, a sealing sheet 105, a developing blade 156, a conveying member 161, a remaining amount detecting member (conductive sheet) 170, a developing (device) frame 150, and the like. The developing frame 150 constitutes a developer container for storing developer (toner). The developing frame 150 consists of a first developing frame 151 and a second developing frame 152, each of which is a resin frame (resin frame). In this embodiment, the first and second developing frames 151, 152 are joined together by ultrasonic welding. However, the first and second developing frames 151, 152 can be fixed to each other by any fixing means, such as bonding, welding, or fastening. The developing frame 150 defines a developing chamber 106, which houses the developing roller 103 and the like, and a developer storage chamber ("storage chamber") 107 for storing toner supplied to the developing roller 103. The developing chamber 106 and the accommodating chamber 107 are partitioned by a partition wall 167 constituted by a portion of the developing frame 150 (the first developing frame 151 ).

[0059] First, within the developing chamber 106, a developing roller 103 is provided as a developer carrying member (developing member) for carrying toner and conveying it toward the developing portion (developing nip) N3, which is the portion (contact portion) facing the photosensitive drum 101. Furthermore, within the developing chamber 106, a supply roller 104 is provided as a supply member for supplying toner to the developing roller 103. Furthermore, within the developing chamber 106, a developing blade 156 is provided as a regulating member. Furthermore, within the developing chamber 106, a sealing sheet 105 is provided as a sealing member.

[0060] The developing roller 103 is a conductive rubber roller prepared by forming a conductive rubber layer as an elastic layer on the outer periphery of a conductive core metal. In this embodiment, the developing roller 103 rotates about a rotation axis B1 (see FIG. 1 ) which is substantially parallel to the longitudinal direction of the developing unit 140. Figure 10 )along Figure 5 That is, the developing roller 103 is rotationally driven in a direction in which the surface movement direction of the photosensitive drum 101 and the surface movement direction of the developing roller 103 become the same (forward) direction in the developing section N3.

[0061] The supply roller 104 is an elastic sponge roller prepared by forming a foam elastic (member) layer as an elastic layer on the outer periphery of a conductive core metal. That is, the supply roller 104 includes a foam member (porous member) on its surface (outer peripheral surface). The supply roller 104 contacts the developing roller 103 with a predetermined intrusion amount, so that the foam elastic layer constituting the surface layer of the supply roller 104 is compressed and recessed by the elastic layer of the developing roller 103 whose rigidity is higher than that of the foam elastic layer. The contact between the developing roller 103 and the supply roller 104, that is, the area where the supply roller 104 is compressed by the developing roller 103 (the area to be compressed) is also referred to as the "supply portion (supply clamping portion) N4". In this embodiment, the supply roller 104 is moved along Figure 5 The arrow R4 direction (counterclockwise direction) in FIG. 1 is about the rotation axis B2 (see FIG. 1 ) which is substantially parallel to the longitudinal direction of the developing unit 140. Figure 10 ) is rotationally driven. That is, the supply roller 104 is rotationally driven in a direction in which the surface movement direction of the developing roller 103 and the surface movement direction of the supply roller 104 become opposite to each other in the supply section N4. In the supply section N4, toner is supplied to the developing roller 103 by the supply roller 104.

[0062] The developing blade 156 is provided so as to contact the surface of the developing roller 103 on the side downstream of the supply portion N4 and upstream of the developing portion N3 with respect to the rotation direction of the developing roller 103 .

[0063] In this embodiment, the development blade 156 includes a regulating portion 156b having a thickness of approximately 0.1 mm, and a support member 156a having a substantially L-shaped cross-section (XZ plane) perpendicular to the longitudinal direction. The regulating portion is formed from an electrically deformable sheet-like member made of metal, and the support member is formed from a plate-like member (metal plate) made of metal. The regulating portion 156b is fixed to the support member 156a at one end (fixed end) relative to the width direction, which is substantially perpendicular to the longitudinal direction. In this embodiment, the regulating portion 156b is fixed to the support member 156a by welding. However, the regulating portion 156b may be fixed to the support member 156a by any other fixing means, such as adhesive bonding, welding, or fastening. The development blade 156 is arranged so that the other end (free end) of the regulating portion 156b relative to the width direction points upstream of the development roller 103 relative to the rotational direction. Furthermore, the regulating portion 156b, near its free end relative to the width direction, contacts the surface of the development roller 103 on its side surface. The developing blade 156 controls the thickness (coating amount) of the toner supplied from the supply roller 104 to the developing roller 103. The developing blade 156 may have a function of applying electric charge to the toner. As described below, the developing blade 156 is held by the developing frame 150.

[0064] Furthermore, a sealing sheet 105 is positioned so as to contact the surface of the developing roller 103 on the side downstream of the developing section N3 and upstream of the supply section N4 relative to the developing roller 103. The sealing sheet 105 is formed of a flexible sheet-like member. In this embodiment, the sealing sheet 105 is formed of a 0.06 mm thick sheet-like member made of polyphenylene sulfide (PPS). The sealing sheet 105 is fixed to the developing frame 150, described later, at one end (fixed end) of the sealing sheet 105 relative to its width direction, which is approximately perpendicular to its longitudinal direction. The sealing sheet 105 is positioned at its other end (free end) relative to the width direction toward the downstream side relative to the rotational direction of the developing roller 103. Furthermore, the sealing sheet 105 contacts the surface of the developing roller 103 on its side surface near its free end relative to the width direction. The sealing sheet 105 prevents toner from leaking from the developing chamber 106 to the outside.

[0065] On the other hand, in this embodiment, the accommodating chamber 107 is located above the developing chamber 106, that is, above the supply roller 104, and accommodates therein the toner to be supplied to the developing chamber 106. That is, in this embodiment, the developing chamber 106 is located below the accommodating chamber 107, and the supply roller 104 is located below the accommodating chamber 107. Incidentally, this positional relationship between the developing chamber 106 and the accommodating chamber 107 is the positional relationship in which the developing unit 140 assumes the posture it assumes when being used for image formation in the image forming apparatus 1. The partition wall 167 separating the developing chamber 106 and the accommodating chamber 107 is provided with an opening 168 for establishing communication between the developing chamber 106 and the accommodating chamber 107, thereby allowing toner to pass from the accommodating chamber 107 toward the developing chamber 106. A conveying member (developer conveying member) for conveying the toner accommodated in the accommodating chamber 107 is provided in the accommodating chamber 107. The conveying member 161 also functions as a stirring member (developer stirring member) for stirring the toner accommodated in the accommodation chamber 107. Further, in the accommodation chamber 107, a remaining amount detecting member (conductive sheet) 170 for detecting the remaining amount of the developer in the developing unit 140 is provided.

[0066] The accommodating chamber 107 generally includes a bottom (surface) 191, a front inner wall surface 192, a top surface 193, and a rear inner wall surface 194. The bottom 191 is formed by the inner wall surface of the partition wall 167. The front inner wall surface 192 is formed by the inner wall surface on the front side of the accommodating chamber 107, extending in the vertical direction to connect the bottom 191 and the top surface 193. The top surface 193 is formed by the inner wall surface extending in the horizontal direction to connect the front inner wall surface 192 and the rear inner wall surface 194. The rear inner wall surface 194 is formed by the inner wall surface on the rear side of the accommodating chamber 107, extending in the vertical direction to connect the top surface 193 and the bottom 191. In this embodiment, the bottom 191 (partition wall 167), top surface 193, and rear inner wall surface 194 of the accommodating chamber 107 are formed by the first developing frame 151. Further, in the present embodiment, the front side inner wall surface 192 of the accommodating chamber 107 and the bottom 195 of the developing chamber 106 are formed by the second developing frame 152. However, the developing frame 150 is not limited to the configuration of the present embodiment, but, for example, the developing frame 150 may be configured by connecting three or more frames to each other, or portions of the developing frame 150 configured by the respective frames may be different from those in the present embodiment.

[0067] The conveying member 161 includes a shaft portion 161a arranged generally parallel to the longitudinal direction of the developing unit 140, and two conveying blades (stirring blades) 161b and 161c, each of which is a flexible sheet-like member and constitutes a conveying portion for conveying toner. The shaft portion 161a is disposed substantially over the entire area between the inner wall surfaces on opposite sides of the accommodating chamber 107 with respect to the longitudinal direction. Each of the conveying blades 161b and 161c is a sheet-like member that extends substantially over the entire area of ​​the shaft portion 161a with respect to the longitudinal direction. Furthermore, each of the conveying blades 161b and 161c is fixed to the shaft portion 161a at one end (fixed end) relative to the width direction (radius of rotation) that is generally perpendicular to the longitudinal direction. Each of the conveying blades 161b and 161c is fixed to the shaft portion 161a by any fixing means, such as bonding, welding, or fastening. The other end of each of the conveying blades 161b and 161c is a free end. The two conveying pieces 161b and 161c are fixed to the outer surface of the shaft portion 161a on the sides opposite to each other so as to extend in opposite directions toward the outside of the shaft portion 161a with respect to the rotation radius direction. Figure 5 The developing unit 140 is driven to rotate in the direction of arrow R5 (counterclockwise) about a rotation axis O that is substantially parallel to the longitudinal direction of the developing unit 140. The shaft portion 161a is driven to rotate in the direction of arrow R5 (counterclockwise) about a rotation axis O that is substantially parallel to the longitudinal direction of the developing unit 140. Figure 5 The conveying member 161 rotates in the direction of arrow R5 in the figure, so that the conveying blades 161b and 161c rotate in the same direction as the rotation of the shaft portion 161a. Thus, the conveying member 161 conveys (stirs) the toner via the conveying blades 161b and 161c. For the conveying blades 161b and 161c, a polyester film, polyphenylene sulfide film, polycarbonate film, or the like, each having an appropriate thickness (e.g., 300 μm) can be used.

[0068] A remaining amount detecting member (conductive sheet) 170 is provided on the front inner wall surface 192 in the accommodating chamber 107. Incidentally, details of the remaining amount detecting configuration for detecting the remaining amount of the developer in the developing unit 140 will be described later.

[0069] like Figure 7As shown in FIG, the developing roller 103 and the supply roller 104 are rotatably supported at their respective opposite ends relative to the longitudinal direction by a drive-side developing bearing 153 and a non-drive-side developing bearing 154. Each of the drive-side developing bearing 153 and the non-drive-side developing bearing 154 is fixed to the developing frame 150 (first developing frame 151, second developing frame 152) by any fixing means, such as bonding, welding, or fastening. Furthermore, in this embodiment, the developing blade 156 is fixed to the developing frame 150, with support portions 156b being fixed to the developing frame 150 (first developing frame 151) at two locations, one at one end and the other at the other end relative to the longitudinal direction, by fixing screws 156c. However, the developing blade 156 may be fixed to the developing frame 150 by any fixing means, such as bonding, welding, or fastening. Furthermore, in this embodiment, the sealing sheet 105 is attached to the developing frame 150 (second developing frame 152) by a double-sided tape as affixed means. However, the sealing sheet 105 may be fixed to the developing frame 150 by any fixing means such as bonding, welding, or fastening. Further, the conveying member 161 (shaft portion 161a) is rotatably supported at opposite ends with respect to the longitudinal direction by the driving side developing bearing 153 and the non-driving side developing bearing 154.

[0070] like Figure 7 As shown in FIG, in the driving side end portion of the developing unit 140 with respect to the longitudinal direction, a developing drive input gear 159 is provided as a drive transmission member for transmitting the driving force of the developing unit 140. The developing drive input gear 159 is provided with a developing drive input coupling portion 159a as a drive input portion. The developing drive input coupling portion 159a is connected to a main assembly side developing drive coupling portion 40 ( Figure 3 and Figure 4 Further, a driving force from a driving motor (not shown) provided in the apparatus main assembly 2 is input into the developing unit 140 through the developing drive input gear 159.

[0071] The driving force input to the developing unit 140 is transmitted from the developing drive input gear 159 to the developing roller gear 157 as a drive transmission member, thereby rotating the developing roller 103. Further, the driving force input to the developing unit 140 is transmitted from the developing drive input gear 159 to the supply roller gear 158 as a drive transmission member, thereby rotating the supply roller 104.

[0072] Furthermore, the driving force input into the developing unit 140 is transmitted from the developing drive input gear 159 to the conveying gear 160 as a drive transmission member, thereby rotating the conveying member 161. The developing roller gear 157, the supply roller gear 158, and the conveying gear 160 are rotatably supported by the driving side developing bearing 153. Furthermore, at the driving side end portion of the developing unit 140 with respect to the longitudinal direction, a developing cover member 155 is provided for supporting the developing drive input gear 159 and for covering the developing drive input gear 159, the developing roller gear 157, the supply roller gear 158, the conveying gear 160, and the like.

[0073] <Assembling the drum unit and developer unit>

[0074] Next, the assembly of the drum unit 120 and the developing unit 140 will be described.

[0075] like Figure 8 As shown in , the drum unit 120 and the developing unit 140 are connected to each other by a driving side box cover member 122 and a non-driving side box cover member 123, which are provided at the opposite ends of the process cartridge 100 with respect to the longitudinal direction. The driving side box cover member 122 provided at the driving side end of the process cartridge 100 with respect to the longitudinal direction is provided with a developing unit supporting hole 122b for swingably (movably) supporting the developing unit 140. Similarly, the non-driving side box cover member 123 is provided with a developing unit supporting hole 123b for swingably supporting the developing unit 140. Further, the driving side box cover member 122 and the non-driving side box cover member 123 are respectively provided with drum supporting holes 122a and 123a for rotatably supporting the photosensitive drum 101.

[0076] At the drive-side end of the process cartridge 100 relative to the longitudinal direction, the outer diameter of the cylindrical portion 155a of the developer cover member 155 engages with the developer unit support hole 122b of the drive-side cover member 122. Furthermore, at the non-drive-side end of the process cartridge 100 relative to the longitudinal direction, the outer diameter of the cylindrical portion (not shown) of the non-drive-side developer bearing 154 engages with the developer unit support hole 123b of the non-drive-side cover member 123. Furthermore, the opposite end of the photosensitive drum 101 relative to the longitudinal direction engages with the drum support hole 122a of the drive-side cover member 122 and the drum support hole 123a of the non-drive-side cover member 123. The drive-side cover member 122 and the non-drive-side cover member 123 are then secured to the drum unit 120 (drum frame 121) using any fixing means, such as screws or adhesive. Thus, the developing unit 140 is rotatably (swingably) supported relative to the drum unit 120 (photosensitive drum 101) by the drive side cover member 122 and the non-drive side cover member 123. Therefore, during image formation, the developing roller 103 can be positioned at a position (in this embodiment, a contact position) where the developing roller 103 acts on the photosensitive drum 101.

[0077] like Figure 9 As shown in FIG, the drum unit 120 and the developing unit 140 are assembled in the above-described manner, thereby integrally forming the process cartridge 100.

[0078] Incidentally, the axis connecting the center of the developing unit support hole 122b of the driving side cartridge cover member 122 and the center of the developing unit support hole 123b of the non-driving side cartridge cover member 123 is also referred to as the swing axis A2. Here, the cylindrical portion 155a of the developing cover member 155 is coaxial with the developing input coupling 159a. In other words, the developing unit 140 is configured so that the driving force is transmitted along the above-mentioned swing axis A2. With the above-mentioned swing axis A2 as the center, the developing unit 140 is rotatably supported relative to the drum unit 120.

[0079] <Remaining amount detection mechanism in the developer unit>

[0080] Next, a remaining amount detection configuration for detecting the remaining amount of the developer in the developing unit 140 in this embodiment will be described.

[0081] Figure 10 is a schematic perspective view of the developing unit 140 (showing a state in which the developing unit 140 is viewed from slightly above along the X2 direction, so that Figure 10 The left side is the drive side and the right side is the non-drive side). Figure 11 is a schematic cross-sectional view of the developing unit 140 at a substantially central portion with respect to the longitudinal direction ( Figure 10QQ cross-sectional view in FIG), shows a state in which a cross section (XZ plane) substantially perpendicular to the Y direction of the developing unit 140 is viewed from the non-driving side. Figure 12 : is a perspective view of the second developing frame 152 (showing a state where the second developing frame 152 is viewed from slightly above along the X2 direction such that the left side is the driving side and the right side is the non-driving side). Figure 13 Part (a) is a schematic front view of the second developing frame 152 as viewed along the X2 direction, ie, from the developing roller 103 side, Figure 13 Part (b) is a schematic side view of the second developing frame 152 viewed from the non-driving side along the Y direction. Figures 10 to 13 Although the developing unit 140 is similar to Figure 5 The developing unit 140 according to the present embodiment is shown in FIG. 1 , but for simplicity, the developing unit 140 (or its components) having a configuration in which the conveying member is provided with only a single conveying sheet 161 b is shown. The same applies to the later described Figures 15 to 17 .

[0082] A recessed portion 163 is formed on the front inner wall surface 192 of the second developing frame 152 (accommodating chamber 107), extending along (substantially parallel to) the longitudinal direction of the second developing frame 152. The recessed portion 163 includes an upper surface (first surface) 163a, which is the inner wall surface of the accommodating chamber 107, and a lower surface (second surface) 163b, which is located downstream of the supply opening 168 and upstream of the upper surface 163a, relative to the longitudinal direction of the conveying member 161. In a cross-section (XZ plane) of the second developing frame 152, which is generally perpendicular to the longitudinal direction, the upper surface 163a is formed by a plane that is inclined so that the distance from the rotation axis O of the conveying member 161 decreases toward the downstream side in the rotational direction of the conveying member 161. Further, in a cross section (XZ plane) of the second developing frame 152 approximately perpendicular to the longitudinal direction, the lower surface 163 b is constituted by a plane inclined so that the distance of the lower surface from the rotation axis O of the conveying member 161 becomes longer toward the downstream side in the rotation direction of the conveying member 161 .

[0083] The upper surface 163a and the lower surface 163b are continuous at the bottom 163c of the recessed portion 163. The conductive sheet 170, which is a sheet-shaped conductive member constituting the remaining amount detecting member, is provided on the upper surface 163a and the lower surface 163b, which are both surfaces forming the recessed portion 163.

[0084] In this embodiment, a first conductive sheet 171 and a second conductive sheet 172 are provided as conductive sheets 170 within the second developing frame 152. The first conductive sheet 171 is provided on the upper surface 163a of the recessed portion 163, and the second conductive sheet 172 is provided on the lower surface 163b of the recessed portion 163. The first conductive sheet 171 and the second conductive sheet 172 are arranged with a recessed portion gap L between them, without contacting each other. On the front inner wall surface 192 of the second developing frame 152 (the accommodating chamber 107), another recessed portion 162 is formed above and adjacent to the recessed portion 163, extending along (approximately parallel to) the longitudinal direction of the second developing frame 152. This other recessed portion 162 includes a vertex 162a continuous with the upper surface 163a of the recessed portion 163, and an inclined surface 162b continuous with the vertex 162a. In a cross section (XZ plane) of the second developing frame 152 substantially perpendicular to the longitudinal direction, the inclined surface 162 b is composed of a flat surface that is inclined so that the distance from the rotation axis O of the conveying member 161 becomes longer toward the downstream side in the rotation direction of the conveying member 161. The first conductive sheet 171 is provided so as to be continuous over two surfaces consisting of the upper surface 163 a of the recessed portion 163 and the inclined surface 162 b of the above-mentioned other recessed portion 162.

[0085] The first conductive sheet 171 is arranged so that its portion provided on the inclined surface 162b of the other recessed portion 162 is continuous with the non-driving side end portion of the second developing frame 152 relative to the longitudinal direction. Further, the second conductive sheet 172 is provided on the lower surface 163b of the recessed portion 163 to be continuous with the non-driving side end portion of the second developing frame 152 relative to the longitudinal direction. The portion of the first conductive sheet 171 provided on the upper surface 163a of the recessed portion 163 and the portion of the second conductive sheet 172 provided on the lower surface 163b of the recessed portion 163 opposite to the portion (of the first conductive sheet 171) are arranged adjacent to each other at a predetermined interval L. That is, the closest portion between the first conductive sheet 171 and the second conductive sheet 172 is limited to a predetermined range (detection range) W, which extends symmetrically from the center of the second developing frame 152 toward each of the opposite end sides relative to the longitudinal direction. The space ( Figure 11 The shaded portion in FIG. 1 is the remaining amount detection unit 164.

[0086] Incidentally, the shape of the recessed portion 163 provided with the remaining amount detecting portion 164 is not limited to that in the present embodiment. For example, an appropriate shape, such as a recessed portion formed of a curved surface, may be used. Furthermore, in the present embodiment, the first conductive sheet 171 is provided on both surfaces of the second developing frame 152 from the perspective of manufacturing, etc. However, similarly to the case of the second conductive sheet 172, it may be provided only on the first surface.

[0087] In this embodiment, the first and second conductive sheets 171 and 172 are formed from conductive resin sheets. In this embodiment, the thickness of the first and second conductive sheets 171 and 172 is 0.1 mm. In this embodiment, a resin sheet with a surface resistivity of 1.15 kΩ / sq or less is used as the first and second conductive sheets 171 and 172. Furthermore, in this embodiment, an ethylene vinyl acetate copolymer (EVA) resin in which carbon black is dispersed is used as the material for the first and second conductive sheets 171 and 172. Furthermore, in this embodiment, the first and second conductive sheets 171 and 172 are integrally molded with the second development frame 152 through insert molding and attached to the second development frame 152. In this embodiment, a 0.1 mm thick resin sheet is used for the first and second conductive sheets 171 and 172 from the perspectives of frame deformation, transfer characteristics to the frame shape, conductivity, and other factors. However, the thickness of the resin sheet can be selected as appropriate. Furthermore, in this embodiment, EVA resin is used as the material for the first conductive sheet 171 and the second conductive sheet 172. However, other resins, such as polystyrene (PS), acrylonitrile butadiene styrene (ABS), and polyphenylene oxide (PRO), may also be used. Furthermore, in this embodiment, resin sheets are used as the first conductive sheet 171 and the second conductive sheet 172 and are attached to the developing frame 150 by insert molding. However, the present invention is not limited to this. For example, sheets made of metal or the like may be used as the first conductive sheet 171 and the second conductive sheet 172, and these sheets may be fixed (adhered) to the developing frame 150 by any fixing means, such as bonding, welding, or fastening.

[0088] Figure 14This is a schematic diagram illustrating a schematic circuit configuration for detecting the remaining amount of developer in the developing unit 140 in this embodiment. A method for measuring the electrostatic capacitance of the remaining amount detecting portion 164 using the first conductive sheet 171 and the second conductive sheet 172 will be described. The apparatus main assembly 2 includes a voltage applying device (power supply) 13 capable of applying an AC voltage (alternating current voltage) as a remaining amount detecting bias (remaining amount detecting voltage) to the first conductive sheet 171, and a remaining amount detecting device (detection circuit) 14 electrically connected to the second conductive sheet 172. Electrical conduction between the first and second conductive sheets 171, 172 disposed within the second developing frame 152 and the voltage applying device 13 and remaining amount detecting device 14 disposed outside the second developing frame 152 need only be established by any method.

[0089] For example, a portion of the second developing frame 152 is made of a conductive resin or a conductive member is incorporated into a portion of the second developing frame 152 so that members inside and outside the second developing frame 152 may be configured to be electrically connected to each other.

[0090] In this embodiment, if Figure 13 As shown in part (b), in the non-driving side end portion of the second developing frame 152, a first conductive resin contact 165a and a second conductive resin contact 165b are provided which are formed integrally with the second developing frame 152 by two-color molding. The first conductive resin contact 165a and the second conductive resin contact 165b contact the first conductive sheet 171 and the second conductive sheet 172, respectively, so that the components inside and outside the developing unit 140 are electrically conductive to each other. Further, through the non-driving side developing bearing 154 ( Figure 7 ), the first conductive sheet 171 and the voltage applying device 13 provided in the apparatus main assembly 2 are connected to each other, and a voltage is applied to the first conductive sheet 171. Further, through the non-driving side developing bearing 154 ( Figure 7 ), the second conductive sheet 172 is connected to the remaining amount detection device 14 provided in the main assembly 2 of the apparatus, and a detection output corresponding to the remaining amount of developer in the developing unit 140 is obtained. The first conductive sheet 171 and the second conductive sheet 172 function as plates and form a capacitor within the developing unit 140. In other words, the first conductive sheet 171 and the second conductive sheet 172 respectively constitute the first electrode and the second electrode of the detection member. The first conductive sheet 171 and the second conductive sheet 172 are arranged (disposed) in the direction of rotation of the conveying member 161 and each extend along the rotation axis of the conveying member 161.

[0091] When an AC voltage is applied to the first conductive sheet 171, a current corresponding to the electrostatic capacitance is induced in the remaining amount detection portion 164 (which is the space between the first conductive sheet 171 and the second conductive sheet 172), causing the current value to be output as a signal. The angle formed between the first conductive sheet 171 and the second conductive sheet 172 in the portion forming the remaining amount detection portion 164 can preferably be set to be greater than 95° and less than 110°, at which the electrostatic capacitance can be stably measured. This electrostatic capacitance varies depending on the amount of developer occupying the remaining amount detection portion 164. The change in electrostatic capacitance is input as a current value to the remaining amount detection portion 164. Then, the controller (control circuit) 15 provided in the main assembly 2 of the device is able to sequentially calculate the remaining amount of developer in the developing unit 140 based on the current value input to the remaining amount detection device 14. Furthermore, the controller 15 can control the display portion 16 provided in the apparatus main assembly 2 or the display portion of an external device (such as a personal computer, etc.) connected to the image forming apparatus 1 to inform the display portion 16 of the remaining amount of developer in the developing unit 140. Incidentally, the electrostatic capacity detection method is not limited to the above-described method. For example, a configuration may be employed in which the first conductive sheet 171 is electrically connected to the remaining amount detection device 14 and the second conductive sheet 172 is electrically connected to a voltage applying device, and in which the electrostatic capacity is detected by applying an AC voltage to the second conductive sheet 172.

[0092] The relationship between the operation of the conveying member 161 and the detection of the developer amount by the remaining amount detecting portion 164 will be further described. As described above, the recessed space between the first conductive sheet 171 and the second conductive sheet 172 in the detection range W is the remaining amount detecting portion 164. Furthermore, the amount of developer conveyed by the conveying member 161 to the remaining amount detecting portion 164 is detected, thereby calculating the remaining developer amount in the developing unit 140, i.e., the "total remaining developer amount," which is the sum of the remaining developer amount in the developer accommodating chamber and the remaining developer amount in the developing chamber.

[0093] Figure 15 Part (a) is similar to the developing unit 140 Figure 11 Schematic cross-sectional view (along Figure 10), and shows a state when the developer (toner) T1 to be conveyed is conveyed to the remaining amount detection portion 164 by the conveying sheet 161b and detected by the remaining amount detection portion 164. In this embodiment, the length of the conveying sheet 161b relative to the width direction is set so that the free end of the free end portion of the conveying sheet 161b can move in contact with at least a portion of the bottom 191 and the front inner wall surface 192 of the accommodating chamber 107. This at least a portion of the front inner wall surface 192 generally includes at least a portion of the lower surface 163b of the recessed portion 163. That is, in a cross section (XZ plane) of the developing unit 140 that is approximately perpendicular to the longitudinal direction, the length of the conveying sheet 161b relative to the width direction is longer than the distance from the rotation axis (rotation center) O of the conveying member 161 to this at least a portion of the bottom 191 and the front inner wall surface 192. For this reason, even in a case such as Figure 15 Even in a case where the amount of developer in the accommodating chamber 107 shown in part (a) is relatively small, the conveying sheet 161b lifts the developer and conveys it to the remaining amount detecting portion 164. Therefore, the conveying member 161 is configured so that its outer free end relative to the direction of the rotation radius moves while in contact with at least a portion of the partition wall 167. Furthermore, when the developing unit 140 is in a posture when the developing unit 140 is being used for image formation in the imaging device 1, the remaining amount detecting portion 164 is provided on the inner wall surface of the accommodating chamber 107 at a position where the free end of the conveying member 161 contacts the inner wall surface immediately after separating from the partition wall 167 while moving upward. That is, when the developing unit 140 is in a posture when the developing unit 140 is being used for image formation in the imaging device 1, at least a portion of the remaining amount detecting portion 164 is provided at a position where the developer is lifted and conveyed by the conveying member 161. In other words, at least a portion of remaining amount detecting portion 164 is provided in an area of ​​the inner wall surface with which the free end of conveying member 161 contacts when the free end of conveying member 161 separates from partition wall 167 and then rotates upward. Incidentally, in this embodiment, conveying sheet 161b conveys the developer while flexing in a direction opposite to the rotational direction of conveying member 161. At this time, the developer (toner) acts as a dielectric material, increasing the electrostatic capacitance between first conductive sheet 171 and second conductive sheet 172, which function as capacitor plates.

[0094] on the other hand, Figure 15 Part (b) is similar to the developing unit 140 Figure 11 Schematic cross-sectional view (along Figure 10), and shows a state immediately after the conveying sheet 161b passes through the recording material detecting portion 164. A portion of the developer T1 to be conveyed is lifted upward beyond the remaining amount detecting portion 164 by the conveying sheet 161b, and a portion of the developer T1 to be conveyed falls from the remaining amount detecting portion 164 due to its own weight, thereby obtaining the state shown in FIG. Figure 15 Therefore, the developer as the dielectric material is consumed (or reduced) in the remaining amount detecting portion 164 , so that the electrostatic capacity between the first conductive sheet 171 and the second conductive sheet 172 is reduced.

[0095] Incidentally, as mentioned above, for simplicity, Figure 15 Only one conveying blade 161b is shown in FIG. 1 , but in this embodiment, each of the two conveying blades 161b and 161c behaves substantially the same with respect to the developer.

[0096] As the developer is consumed by image formation, the amount of developer conveyed by conveying member 161 gradually decreases. Consequently, the "time during which the developer remains in remaining amount detection portion 164," i.e., the "time during which the electrostatic capacity increases," similarly decreases. In this embodiment, remaining amount detection device 14 is configured to detect the remaining amount of developer in developing unit 140 by measuring this decrease in the "time during which the electrostatic capacity increases."

[0097] Here, in order to improve the detection accuracy of the remaining developer amount in the developing unit 140 , the developing unit 140 is required to be configured so that the calculation result of the above-mentioned total remaining developer amount is more stable.

[0098] Improved accuracy in detecting the remaining developer amount

[0099] Next, we will use Figure 11 、 Figure 16 and Figure 17 A configuration for improving the accuracy of detecting the remaining amount of developer in the developing unit 140 will be described.

[0100] As features of the developing unit 140 , the following three features (first to third features) can be cited.

[0101] As a first feature, with respect to the rotation direction of the conveying member 161 ( Figure 11 The remaining amount detecting portion 164 is arranged on the downstream side of the supply opening 168. That is, the remaining amount detecting portion 164 is arranged on the downstream side of the supply opening 168 with respect to the moving direction of the conveying sheet 161b (indicated by the free end relative to the width direction), that is, with respect to the conveying direction of the developer conveyed by the conveying member 161. However, with respect to the rotation direction ( Figure 11), the remaining amount detection portion 164 is arranged on the upstream side of the area I, which is the area of ​​the inner wall surface of the accommodating chamber 107, and the area I is positioned on the side opposite to the supply opening 168 relative to the rotation axis O of the conveying member 161.

[0102] In other words, if Figure 11 As shown in FIG, the remaining amount detecting portion 164 is located in the rotation direction ( Figure 11 In the area between the first point 168e2 and the second point 151a, wherein the first point 168e2 is the supply opening 168 with respect to the rotation direction ( Figure 11 The downstream end of the second point 151a is a point at which the supply opening 168 passes through the supply opening 168 with respect to the rotation direction ( Figure 11 A virtual line between the upstream end 168e1 (in the direction of arrow R5) and the rotation axis O intersects (intersects) the inner wall surface.

[0103] From the viewpoint of, for example, the conveying characteristics of the conveying sheet 161b conveying the developer to the remaining amount detecting portion 164, the remaining amount detecting portion 164 may be preferably provided at a position whose height does not exceed the height of the horizontal line H passing through the rotation axis O of the conveying member 161. That is, it is preferable that at least a portion of the remaining amount detecting portion 164 is positioned at a height in the gravity direction that does not exceed the height of the horizontal line H passing through the rotation axis O of the conveying member 161.

[0104] As a second feature, the rotation direction of the conveying member 161 ( Figure 11 The direction of the arrow R5 in FIG) and the direction of rotation of the supply roller 104 ( Figure 11 The arrow R4 direction) is the same direction.

[0105] As the third characteristic, in the direction of gravity ( Figure 11 168 ). The rotation axis B2 of the supply roller 104 is positioned at a position not lower than the rotation axis B1 of the developing roller 103 (in the direction of arrow Z2 in FIG). However, typically, the rotation axis B2 of the supply roller 104 is positioned on the opposite side of the photosensitive drum 101 relative to a vertical line passing through the rotation axis B1 of the developing roller 103. In other words, the rotation axis B2 of the supply roller 104 is positioned closer to the supply opening 168 than the rotation axis B1 of the developing roller 103.

[0106] Incidentally, the above-described positional relationship (operational relationship) may only need to be satisfied when the developing unit 140 assumes a posture when the developing unit 140 is used for image formation in the image forming apparatus 1. Further, the above-described positional relationship (operational relationship) is a positional relationship when the developing unit 140 is viewed in a cross section substantially perpendicular to the longitudinal direction of the developing unit.

[0107] Here, a phenomenon that affects the detection accuracy of the remaining amount of developer in the developing unit 140 will be described.

[0108] Figure 16 Part (a) is a schematic cross-sectional view of the vicinity of the supply roller 104 in a state where the developer (toner) T2 to be filled is filled in the developing chamber 106 (showing a state of a cross section (XZ plane) approximately perpendicular to the Y direction as viewed from the non-driving side). The supply roller 104 includes a sleeve (foam elastic member layer) formed of a sponge (foam elastic member), and holds the developer therein. In the developing chamber 106, the developing roller 103 and the supply roller 104 are in contact with each other in the longitudinal direction, and the sponge of the supply roller 104 is partially compressed by the developing roller 103 having a higher hardness, thereby forming a supply portion (area to be compressed, supply clamping portion) N4. Then, in the vicinity of the supply portion N4 on the upstream side relative to the rotation direction R4 of the supply roller 104, the state of the supply roller 104 changes from a state in which the sponge is not compressed to a state in which the sponge is compressed. For this reason, the developer inside the sponge is discharged from the sponge, as shown in FIG. Figure 16 On the other hand, in the vicinity of the downstream side of the supply portion N4, the state of the supply roller 104 is restored from the state where the sponge is compressed to the state where the sponge is not compressed. For this reason, the developer at the periphery of the sponge is absorbed by the sponge, as shown in FIG. Figure 16 As shown by arrow E in part (a).

[0109] Figure 16 Part (b) is a schematic cross-sectional view of the vicinity of the supply roller 104, illustrating the behavior of the developer in the developing chamber 106 as the supply roller 104 discharges and absorbs the developer (showing a state of a cross section (XZ plane) substantially perpendicular to the Y direction as viewed from the non-driven side). On the downstream side of the supply portion N4 relative to the rotational direction R4 of the supply roller 104, the developer decreases due to the absorption of the developer (arrow E). Therefore, the developer T2 to be filled in the developing chamber 106 is shown as follows. Figure 16 , resulting in a gap S in the developing chamber 106. The volume of the gap S fluctuates depending on the developer consumption amount of the image to be formed and the state of the supply roller 104, making it difficult to estimate the volume of the gap S.

[0110] As described above, the remaining amount detection unit 164 detects the amount of developer conveyed by the conveying member 161 in the accommodating chamber 107. Furthermore, the total remaining developer amount is calculated as the sum of the developer amount in the accommodating chamber 107 and the developer amount in the developing chamber 106. In other words, the developer amount detected by the remaining amount detection unit 164 is simply the "amount of developer conveyed in the accommodating chamber 107" and does not include parameters corresponding to the developer amount in the developing chamber 106. However, as described above, the amount of developer in the developing chamber 106 fluctuates due to the formation of the gap S (its volume fluctuates). Consequently, a discrepancy arises between the calculated total remaining developer amount and the actual remaining developer amount in the developing chamber 106, potentially reducing the accuracy of detecting the remaining developer amount.

[0111] Next, the effects of the configuration of this embodiment will be described. Figure 17 is with Figure 11 A schematic cross-sectional view of a developing unit 140 similar to the developing unit 140 in FIG. 1 is used to illustrate the effect of the configuration of this embodiment.

[0112] With the first feature described above, the conveying blade 161b passes through the supply opening 168 before conveying the developer T1 to be conveyed to the remaining amount detection portion 164. Consequently, the developer amount detected by the remaining amount detection portion 164 becomes the developer amount conveyed by the conveying member 161 based on the developer amount in the accommodating chamber 107 after the developer fills the gap S in the developing chamber 106. In other words, with the positional relationship described in the first feature, it is easier to achieve a state in which the developer fills the gap S in the developing chamber 106 when the developer amount is detected by the remaining amount detection portion 164. Consequently, the gap S, which can cause fluctuations in the detection result of the developer amount in the remaining amount detection portion 164, is reduced, facilitating the stabilization of the developer amount in the developing chamber 106. Consequently, the calculation result of the total remaining developer amount (which is the sum of the developer amounts in the accommodating chamber 107 and the developer amount in the developing chamber 106) is stabilized, thereby improving the accuracy of detecting the developer in the developing unit 140.

[0113] Here, in order to further enhance the effect of the first feature, it is desirable that a gap S exists on the downstream side of the supply opening 168 relative to the conveying direction (the direction along the rotation direction R5) in which the developer is conveyed by the conveying member 161. Figure 17 As shown by the arrow G in FIG, the developer conveyed by the conveying member 161 is more smoothly filled in the gap S. For this reason, by the above-mentioned second feature, the position where the supply roller 104 discharges (arrow D) and absorbs (arrow E) the developer provides the following: Figure 17. That is, with respect to the direction in which the developer is conveyed by the conveying member 161, the developer is easily discharged from the supply roller 104 toward the upstream side of the supply opening 168. Furthermore, the developer positioned on the downstream side of the supply opening 168 with respect to the direction in which the developer is conveyed by the conveying member 161 is easily absorbed by the supply roller 104. Thus, a gap S is easily generated on the downstream side of the supply opening 168 with respect to the direction in which the developer is conveyed by the conveying member 161.

[0114] Furthermore, to further reliably achieve the effects of the second feature described above, the developing unit 140 may preferably include the third feature described above. This third feature prevents the positional relationship between the locations where the developer is discharged (arrow D) and absorbed (arrow E) by the supply roller 104 from being reversed. In other words, the developer is prevented from being easily discharged from the supply roller 104 downstream of the supply opening 168, and the developer positioned upstream of the supply opening 168 is prevented from being easily absorbed. Consequently, a state can be achieved that facilitates the generation of a gap S downstream of the supply opening 168 relative to the direction in which the developer is conveyed by the conveying member 161.

[0115] In this embodiment, the developing unit 140 has the first to third features described above. However, when the first feature is provided, a corresponding effect similar to the above effect can be obtained. Furthermore, for example, in the case of a configuration in which the supply roller 104 includes a foamed elastic member layer constituting a surface layer, providing the second and third features described above makes it possible to further enhance the effect of improving the detection accuracy of the remaining developer amount in the developing unit 140.

[0116] As described above, according to this embodiment, the detection of the developer amount by remaining amount detection section 164 can be performed while the gap in developing chamber 106, which causes the developer amount detected by remaining amount detection section 164 to fluctuate, is filled with developer. As a result, the value of the total remaining developer amount (which is the calculated sum of the developer amount in accommodating chamber 107 and the developer amount in developing chamber 106) is stabilized. Consequently, the accuracy of detecting the remaining developer amount in developing unit 140 is improved.

[0117] [Other Examples]

[0118] Hereinabove, the present invention has been described based on the specific embodiments, but the present invention is not limited to the above embodiments.

[0119] In the above embodiment, the imaging device is a process cartridge type, but the present invention is not limited thereto. The developing device may be fixed to the device main assembly of the imaging device. Further, the developing device may be made so as to be removably mounted to the device main assembly of the imaging device substantially individually. Further, the imaging device may have a configuration in which the developer can be supplied from a supply container to the developing device fixed to or removably mounted to the device main assembly. In this case, the supply container may be mounted to the developing device during the supply of the developer and then removed from the developing device before performing imaging, or imaging may be performed while the supply container is mounted to the developing device as is.

[0120] Furthermore, in the above embodiment, an electrostatic capacity type is used as the developer remaining amount detection type, but the present invention is not limited to this. As the developer remaining amount detection type, for example, any available type, such as a light transmission type, can be used. The light transmission type is a type that uses a light source for illuminating the detection portion in the accommodating chamber with light and a light receiving portion for receiving light that has passed through the interior of the developing device, and detects the developer amount based on changes in the light receiving state (presence / absence of received light, amount of light received, duration of light reception) of the light receiving portion.

[0121] Furthermore, in the above embodiment, the supply roller is rotationally driven in a direction such that the surface movement direction of the developing roller and the surface movement direction of the supply roller are opposite in the portion (contact portion) facing the developing roller. However, the present invention is not limited to this. The supply roller may be rotationally driven in a direction such that the surface movement direction of the developing roller and the surface movement direction of the supply roller are the same (positive) direction in the portion (contact portion) facing the developing roller. In this case as well, according to the above embodiment, the above-mentioned features are provided, thereby achieving effects similar to those of the above embodiment.

[0122] While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims

1. A developing device for imaging in an imaging device, comprising: a developing roller configured to carry a developer; a supply roller configured to contact the developing roller and supply the developer to the developing roller; and a developing container, the developing roller being rotatably supported by the developing container, the developing container comprising: a developing chamber provided with the supply roller, a developer accommodating chamber separated from the developing chamber by a partition wall provided with an opening and configured to accommodate developer, the developer accommodating chamber communicating with the developing chamber through the opening and positioned above the developing chamber when the developing device assumes a posture in which the developing device is used for image formation, a conveying member provided in the developer accommodating chamber and configured to convey the developer from the developer accommodating chamber toward the developing chamber through the opening, the conveying member being rotatable about its rotation axis in a rotation direction opposite to a rotation direction of the supply roller, and a detection portion configured to output a signal according to an amount of developer accommodated in the developing chamber, the detection portion being provided on an inner wall surface constituting the developer accommodating chamber, wherein, in a cross section perpendicular to the rotation axis, the detection portion is arranged in an area of ​​the inner wall surface positioned between a first point and a second point relative to the rotation direction of the conveying member, the first point being the downstream end of the opening relative to the rotation direction, and the second point being a point at which a virtual line passing through the rotation axis and the upstream end of the opening relative to the rotation direction intersects the inner wall surface.

2. The developing device according to claim 1, wherein With the developing device taking the posture, the rotation axis of the supply roller is positioned at a height not lower than a height of the rotation axis of the developing roller in the direction of gravity.

3. The developing device according to claim 1, wherein The supply roller includes a foamed elastic layer constituting a surface layer, and the foamed elastic layer is compressed by the developing roller in a contact portion between the supply roller and the developing roller.

4. The developing device according to claim 1, wherein When the developing device takes the posture, at least a portion of the detecting portion is provided in a position to which the developer lifted and conveyed by the conveying member is supplied.

5. The developing device according to claim 4, wherein When the developing device takes the posture, at least a portion of the detecting portion is positioned at a height not lower than a height of a horizontal line passing through the rotation axis of the conveying member in the direction of gravity.

6. The developing device according to claim 1, wherein The conveying member is configured to move while contacting at least a portion of the partition wall at an outer free end portion of the conveying member in a rotation radius direction thereof, and Here, when the developing device takes the posture, the detection portion is provided on a region of the inner wall surface with which the free end portion of the conveying member contacts when rotating upward after being separated from the partition wall.

7. The developing device according to claim 6, wherein: When the developing device takes the posture, at least a portion of the detecting portion is positioned at a height not lower than a height of a horizontal line passing through the rotation axis of the conveying member in the direction of gravity.

8. The developing device according to claim 1, wherein The detecting portion is provided in a recessed portion recessed toward the outside of an inner wall surface of the developer accommodating chamber.

9. The developing device according to claim 8, wherein The detection portion includes a first electrode and a second electrode provided on a first surface and a second surface, respectively, the first surface and the second surface constituting the recessed portion and facing each other, and the detection portion transmits a signal according to an electrostatic capacity between the first electrode and the second electrode, and The developer is supplied between the first electrode and the second electrode by the rotation of the conveying member.

10. The developing device according to claim 9, wherein The first electrode and the second electrode are arranged in a rotational direction of the conveying member, and each of the first electrode and the second electrode extends in a direction of a rotational axis of the conveying member.

11. The developing device according to claim 10, wherein: In the cross section, the first surface is inclined so that the distance from the rotation axis of the conveying member becomes shorter toward the downstream side in the rotation direction of the conveying member, and wherein, in the cross section, the second surface is arranged in an area of ​​the inner wall surface between the first point and the second point relative to the rotation direction of the conveying member, and the second surface is inclined so that the distance from the rotation axis of the conveying member becomes longer toward the downstream side of the conveying member.

Images