Developing device

Abstract

To improve the detection accuracy of the remaining amount of developer in a developing device.SOLUTION: A developing device 140 comprises: a developing chamber 106; a developer accommodating chamber 107 partitioned from the developing chamber 106 by a partition wall 167 including an opening 168; a developing roller 103; a supplying roller 104; a conveying member 161 provided in the developer accommodating chamber 107; and a detecting portion 164 for detecting a remaining amount of developer in the developing device 140, the detecting portion 164 being provided in the developer accommodating chamber 107 and being supplied with the developer conveyed by the conveying member 161. The developing chamber 106 is provided below the developer accommodating chamber 107. The detecting portion 164 is arranged, in a rotation direction of the conveying member 161, downstream of the opening 168 and upstream of a position facing the opening 168 across a rotation axis of the conveying member 161 in the inner wall surface of the developer accommodating chamber 107. The rotation direction of the supplying roller 104 is the same as the rotation direction of the conveying member 161.SELECTED DRAWING: Figure 11

Description

[Technical Field]

[0001] The present invention relates to a developing device used in an image forming apparatus such as a copying machine, printer, facsimile machine, or multifunction machine having two or more of the functions of these machines, which uses an electrophotographic or electrostatic recording method. [Background technology]

[0002] Conventionally, image forming apparatuses such as electrophotographic printers have a developing device that develops an electrostatic latent image formed on an image carrier with a developer. The developing device is detachably mounted to the main body of the image forming apparatus substantially independently, or is detachably mounted to the main body of the image forming apparatus together with other elements as a process cartridge.

[0003] The developing device has a developing chamber in which a developing member that supplies developer to an image carrier is provided, and a developer storage chamber (hereinafter simply referred to as "storage chamber") in which the developer to be supplied to the developing chamber is stored. The storage chamber and the developing chamber are separated by a partition wall, and the developer is supplied from the storage chamber to the developing chamber through a supply opening, which is an opening provided in the partition wall. A rotatable transport member that transports the developer is often provided inside the storage chamber.

[0004] The developing device may also be provided with a remaining amount detection unit that detects the remaining amount of developer in the developing device, which decreases as images are formed. The image forming device can notify the user of the detected remaining amount of developer in the developing device (or the amount of developer consumed).

[0005] Patent Document 1 discloses a configuration in which a remaining amount detection unit is provided in a storage chamber to detect the remaining amount of developer in a developing device. When a remaining amount detection unit is provided in the storage chamber in this way, the remaining amount of developer in the developing device is calculated based on the amount of developer detected in the storage chamber, by adding up the "amount of developer in the storage chamber" and the "amount of developer in the developing chamber." [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-209897 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the conventional configuration described above, the remaining amount detection unit is located upstream of the supply opening that connects the developer storage chamber and the developing chamber in the direction of rotation of the transport member in the storage chamber (the direction in which the transport member transports the developer). Therefore, the amount of developer detected by the remaining amount detection unit includes the "amount of developer remaining in the storage chamber" and the "amount of developer filling the gap in the developing chamber." The latter of these varies depending on factors such as the amount of developer consumed during image formation (the volume of the gap formed in the developing chamber), making it difficult to accurately estimate. Therefore, the amount of developer detected by the remaining amount detection unit may vary, resulting in a discrepancy between the calculated "total remaining amount of developer" and the actual amount of developer remaining in the developing device.

[0008] SUMMARY OF THE INVENTION It is therefore an object of the present invention to improve the accuracy of detecting the remaining amount of developer in a developing device. [Means for solving the problem]

[0009] The above object is achieved by a developing device according to the present invention. In summary, according to one aspect of the present invention, a developing device used for image formation in an image forming apparatus includes a developing chamber, a developer storage chamber separated from the developing chamber by a partition wall, communicating with the developing chamber through an opening provided in the partition wall and storing developer to be supplied to the developing chamber, a developing roller provided in the developing chamber and rotating to transport the developer to an image carrier, a supply roller provided in the developing chamber and in contact with the developing roller and rotating to supply the developer to the developing roller, a transport member provided in the developer storage chamber and rotating to transport the developer in the developer storage chamber and supply the developer to the developing chamber through the opening, and the developing device includes: a detection unit for detecting the remaining amount of developer in the developer storage chamber, the detection unit being provided in the developer storage chamber and supplied with developer transported by the transport member, wherein when the developing device is in a position when used for image formation in the image forming apparatus, the developing chamber is provided below the developer storage chamber, the detection unit is located downstream of the opening in the rotation direction of the transport member and upstream of an area on the inner wall surface of the developer storage chamber that is on the opposite side to the opening with respect to the rotation axis of the transport member, and the rotation direction of the supply roller is the same as the rotation direction of the transport member. [Effects of the Invention]

[0010] According to the present invention, it is possible to improve the accuracy of detecting the remaining amount of developer in the developing device. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic cross-sectional view of an image forming apparatus. [Figure 2] FIG. 2 is a schematic cross-sectional view of the image forming apparatus with the front door open. [Figure 3] FIG. 2 is a schematic cross-sectional view of the image forming apparatus with the cartridge tray pulled out. [Figure 4] FIG. 2 is a schematic cross-sectional view of the image forming apparatus with the process cartridge removed. [Figure 5] FIG. 2 is a cross-sectional view of the process cartridge. [Figure 6] FIG. 2 is an exploded perspective view of the drum unit. [Figure 7] FIG. [Figure 8] FIG. 2 is an assembled perspective view of the process cartridge. [Figure 9] FIG. 2 is a perspective view of the process cartridge. [Figure 10] 1 is a schematic perspective view of a developing unit. [Figure 11] FIG. 2 is a schematic cross-sectional view of a developing unit. [Figure 12] FIG. 2 is a schematic perspective view of a second developing frame. [Figure 13] 3A and 3B are a schematic front view and a schematic side view of a second developing frame; [Figure 14] FIG. 2 is a schematic diagram of a developer remaining amount detection configuration. [Figure 15] 10 is a schematic cross-sectional view of a developing unit for explaining transport of developer to a remaining amount detection portion. FIG. [Figure 16] FIG. 10 is a schematic cross-sectional view of the vicinity of a developing chamber for explaining the problem. [Figure 17] FIG. 4 is a schematic cross-sectional view of a developing unit for explaining the effects of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] The developing device according to the present invention will be described in more detail below with reference to examples. However, the functions, materials, shapes, dimensions, relative positions, etc. of the components described in the following examples may be changed as appropriate depending on the configuration of the device to which the present invention is applied and various conditions. In other words, the present invention is not limited to the following examples.

[0013] [Example 1] <Overall Configuration and Operation of Image Forming Apparatus> First, the overall configuration and operation of the image forming apparatus of this embodiment will be described.

[0014] FIG. 1 is a schematic cross-sectional view of an image forming apparatus 1 according to this embodiment. The image forming apparatus 1 according to this embodiment is a tandem laser beam printer employing an intermediate transfer system capable of forming a full-color image on a sheet-like recording material P using an electrophotographic image formation process. The image forming apparatus 1 also employs a process cartridge system, in which process cartridges 100 (100Y, 100M, 100C, 100K) are removably mounted to a main body 2 of the image forming apparatus to form images. In this embodiment, the main body 2 of the image forming apparatus 1 is the image forming apparatus 1 excluding the process cartridges 100 (100Y, 100M, 100C, 100K). While the recording material P is sometimes referred to as paper, the recording material P also includes materials other than paper or materials containing materials other than paper (e.g., synthetic paper or film formed using synthetic resin, metal-deposited paper with a metal layer, etc.).

[0015] Here, with regard to the image forming apparatus 1 and its elements, the right side in FIG. 1 where a front door 10 described later is provided is referred to as the "front (front)" side, and the left side in FIG. 1 opposite to this front side is referred to as the "rear (back)" side. Also, with regard to the image forming apparatus 1 and its elements, when the image forming apparatus 1 is viewed from the front side, the right side is referred to as the "drive side" and the left side is referred to as the "non-drive side". The drive side is the side on which a drum coupling member for inputting a drive force to a photosensitive drum 101 described later and a development coupling member for inputting a drive force to a developing roller 103 described later are arranged. Also, with regard to the image forming apparatus 1 and its elements, up and down refer to up and down in the direction of gravity (vertical direction), but do not mean just directly above and just below, but also include above and below a horizontal plane passing through an element or position of interest. The left-right direction in FIG. 1 connecting the front side and the rear side is referred to as the "X direction", the direction perpendicular to the plane of FIG. 1 connecting the non-drive side and the drive side is referred to as the "Y direction", and a direction perpendicular to the X direction and the Y direction is referred to as the "Y direction". The direction in which the image is formed is referred to as the "Z direction." The image forming apparatus 1 is disposed so that the Z direction is approximately parallel to the direction of gravity (the X direction and Y direction are each approximately parallel to the horizontal direction), and is used for image formation. The Y direction is also approximately parallel to the rotation axis direction of the photosensitive drum 101 and the developing roller 103. In the X direction, the direction from the front side to the rear side is referred to as the "X1 direction," and the direction from the rear side to the front side is referred to as the "X2 direction." In the Z direction, the direction from the bottom side to the top side is referred to as the "Z1 direction." , and the direction from top to bottom is referred to as the "Z2 direction." That is, the image forming apparatus 1 is disposed so that the Z2 direction is the direction of gravity and is used for image formation. In addition, in the Y direction, the direction from the non-drive side to the drive side is referred to as the "Y1 direction," and the direction from the drive side to the non-drive side is referred to as the "Y2 direction." FIG. 1 is a schematic cross-sectional view of the image forming apparatus 1 showing a cross section (XZ plane) approximately perpendicular to the Y direction as viewed from the non-drive side, with the front of the page being the non-drive side and the back of the page being the drive side.

[0016] The image forming apparatus 1 has a plurality of image forming units (stations), namely, four image forming units 3Y, 3M, 3C, and 3K that form images of yellow (Y), magenta (M), cyan (C), and black (K), respectively. The four image forming units 3Y, 3M, 3C, and 3K are arranged in a row along the direction of movement of the image transfer surface of an intermediate transfer belt 51, which will be described later. In this embodiment, this arrangement direction is along the horizontal direction when the image forming apparatus 1 is installed on a horizontal surface, but is slightly inclined relative to the horizontal direction. Note that elements provided for each color and having the same or corresponding functions or configurations may be generally described by omitting the Y, M, C, or K suffix to the reference numeral indicating that the element is for one of the colors. In this embodiment, the image forming unit 3 is configured to include photosensitive drums 101 (101Y, 101M, 101C, and 101K), charging rollers 102 (102Y, 102M, 102C, and 102K), a laser scanner unit (exposure device) 11, and a developing unit (developing device) 140. In this embodiment, the laser scanner unit 11 is configured as a single unit that exposes the four photosensitive drums 101Y, 101M, 101C, and 101K, but may be provided independently for each photosensitive drum 101.

[0017] The photosensitive drum 101, a rotatable drum-type (cylindrical) photosensitive member (electrophotographic photosensitive member) serving as an image carrier, is rotated in the direction of arrow R1 (clockwise) in the figure at a predetermined peripheral speed (process speed). The surface (outer periphery) 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-type charging member serving as a charging means. The charging roller 102 is disposed in contact with the surface of the photosensitive drum 101 and rotates in accordance with the rotation of the photosensitive drum 101. During charging, a predetermined charging bias (charging voltage), which is a DC voltage of the same polarity as the charging polarity (negative in this embodiment) of the photosensitive drum 101, is applied to the charging roller 102 by a charging power supply (not shown) serving as a charging voltage application unit. The charged surface of the photosensitive drum 101 is scanned and exposed by a laser scanner unit 11 with laser light 12 corresponding to image signals of color components corresponding to each image forming unit 3. As a result, an electrostatic latent image (electrostatic image) is formed on the photosensitive drum 101 in accordance with the image signal of the color component corresponding to each image forming unit 3.

[0018] The electrostatic latent image formed on the photosensitive drum 101 is developed (visualized) by a developing unit 140 serving as a developing means, which supplies a developer (hereinafter also referred to as "toner") and forms a toner image (toner image, developer image) on the photosensitive drum 101. In this embodiment, the developing unit 140 uses a non-magnetic one-component developer (toner) as the developer. The developing unit 140 has a developing roller 103 serving as a developer carrier (developing member). The developing roller 103 carries the toner and transports it to a developing section that faces (contacts) the photosensitive drum 101. During development, the developing roller 103 contacts the photosensitive drum 101. During development, the developing roller 103 is rotationally driven at a predetermined peripheral speed in a direction in which the movement direction of the surface of the photosensitive drum 101 and the movement direction of the surface (outer circumferential surface) of the developing roller 103 are forward directions in the developing section. During development, a predetermined development bias (development voltage), which is a DC voltage having the same polarity as the charge polarity (negative in this embodiment) of the photosensitive drum 101, is applied to the development roller 103 by a development power supply (not shown) serving as a development voltage application unit. As a result, toner is supplied from the development roller 103 to the photosensitive drum 101 in accordance with the electrostatic latent image on the photosensitive drum 101, and the electrostatic latent image on the photosensitive drum 101 is developed. In this embodiment, toner charged with the same polarity as the charge polarity (negative in this embodiment) of the photosensitive drum 101 adheres to the exposed portion (image portion) of the photosensitive drum 101, which has been uniformly charged and then exposed to light, thereby reducing the absolute value of the potential (reverse development method). In this embodiment, the normal charge polarity of the toner, which is the main charge polarity of the toner during development, is negative.

[0019] An intermediate transfer unit 5 is disposed below the four photosensitive drums 101Y, 101M, 101C, and 101K so as to face these four photosensitive drums 101Y, 101M, 101C, and 101K. The intermediate transfer unit 5 includes an intermediate transfer belt 51 configured as an endless belt serving as an intermediate transfer body, a drive roller 52 and a tension roller 53 serving as multiple support rollers, and four primary transfer rollers 54Y, 54M, 54C, and 54K. The flexible intermediate transfer belt 51 is stretched around the drive roller 52 and the tension roller 53 and stretched with a predetermined tension. Furthermore, primary transfer rollers 54Y, 54M, 54C, and 54K, which are roller-type primary transfer members serving as primary transfer means, are disposed on the inner circumferential surface of the intermediate transfer belt 51, corresponding to each of the photosensitive drums 101Y, 101M, 101C, and 101K. The primary transfer rollers 54 press the intermediate transfer belt 51 toward the photosensitive drums 101, forming primary transfer portions (primary transfer nips) N1 (N1Y, N1M, N1C, N1K) at the contact points between the photosensitive drums 101 and the intermediate transfer belt 51. In this embodiment, the lower surface of each photosensitive drum 101 contacts the upper surface of the intermediate transfer belt 51. This contact point is the primary transfer portion N1. The intermediate transfer belt 51 receives a driving force transmitted by the rotation of the drive roller 53, causing it to rotate (circularly move) in the direction of arrow R2 (counterclockwise) in the figure. The tension roller 52 and each primary transfer roller 54 are driven to rotate in accordance with the rotation of the intermediate transfer belt 51. The toner image formed on the photosensitive drum 101 is transferred (primary transfer) onto the rotating intermediate transfer belt 51 at the primary transfer portion N1. During the primary transfer, a predetermined primary transfer bias (primary transfer voltage), which is a DC voltage of a polarity opposite to the normal charging polarity of the toner (positive polarity in this embodiment), is applied to the primary transfer roller 54. For example, when a full-color image is formed, the toner images of yellow, magenta, cyan, and black formed on the photosensitive drums 101 are transferred onto the intermediate transfer belt 51 so as to be superimposed on each other within the same image forming area.

[0020] When the image forming operation is started, the rotational driving of each photosensitive drum 101, the rotational driving 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 process of the surface of the photosensitive drum 101 by each charging roller 102 is started.

[0021] A secondary transfer roller 6, a roller-type secondary transfer member serving as a secondary transfer means, is disposed on the outer peripheral surface of the intermediate transfer belt 51, facing the drive roller 53. The secondary transfer roller 6 is pressed against the drive roller 53 and contacts the drive roller 53 via the intermediate transfer belt 51, 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 is driven to rotate in accordance with the rotation of the intermediate transfer belt 51. The toner image formed on the intermediate transfer belt 51 is transferred (secondary transfer) onto a recording material P, which is sandwiched and conveyed between the intermediate transfer belt 51 and the secondary transfer roller 6, at the secondary transfer portion N2. During secondary transfer, a predetermined secondary transfer bias (secondary transfer voltage), which is a DC voltage of opposite polarity (positive polarity in this embodiment) to the normal charging polarity of the toner, is applied to the secondary transfer roller 6. The recording material P (recording medium, transfer material, paper, sheet) is supplied to the secondary transfer portion N2 from a feeding unit 4 disposed below the intermediate transfer unit 5. The feeding unit 4 is configured to include a paper feed tray 41 in which recording materials P such as paper are stacked and stored, and a paper feed roller 42 as a feeding member. At a predetermined control timing, the recording materials P are separated and fed one by one from the paper feed tray 41 by the paper feed roller 42, and are conveyed to a pair of registration rollers 70 as a recording material conveying member. This recording material P is conveyed to the secondary transfer portion N2 by the pair of registration rollers 70 at a predetermined control timing.

[0022] The recording material P onto which the toner image has been transferred is conveyed to a fixing device 7 serving as a fixing means. The fixing device 7 applies heat and pressure to the recording material P bearing the unfixed toner image, thereby fixing (melting and solidifying) the toner image onto the recording material P. The recording material P onto which the toner image has been fixed is discharged (output) onto a discharge tray 9 serving as a discharge unit provided outside (on top of) the device main body 2 by a pair of discharge rollers 8 serving as a discharge member.

[0023] In this embodiment, in each image forming unit 3, the photosensitive drum 101 and the charging roller 102 and developing unit 140 acting as process means thereon integrally constitute a process cartridge 100 that is detachably attached to the apparatus main body 2. In this embodiment, four process cartridges 100Y, 100M, 100C, and 100K are detachably attached to the apparatus main body 2. Each of the four process cartridges 100Y, 100M, 100C, and 100K has a similar electrophotographic process mechanism but uses different toner colors. The toner filling amounts may also differ between at least two of the process cartridges 100. A rotational driving force is transmitted to the process cartridges 100 from a drive output unit (details of which will be described later) of the apparatus main body 2, and electrical biases (such as a charging bias, a developing bias, and a remaining amount detection bias) are supplied from contacts (not shown) of the apparatus main body 2. The number of process cartridges detachably attached to the apparatus main body of the image forming apparatus is not limited to four and may be set as needed.

[0024] <Process cartridge attachment / detachment configuration> Next, the mounting and demounting of the process cartridge 100 to and from the apparatus main body 2 in this embodiment will be described.

[0025] 1, the image forming apparatus 1 is provided with a movable cartridge tray 20 that supports the process cartridge 100. The image forming apparatus 1 is also provided with an openable front door 10 that allows the process cartridge 100 to be attached to and detached from the apparatus main body 2. In this embodiment, the front door 10 is rotatable about a rotation axis provided at the lower end thereof that is approximately parallel to the Y direction, and when in a closed state, the front door 10 is opened by moving its upper end downward, and closed by moving its upper end upward.

[0026] Fig. 2 is a schematic cross-sectional view of the image forming apparatus 1 in a state where the front door 10 is open and the cartridge tray 20 is located inside the apparatus main body 2. Fig. 3 is a schematic cross-sectional view of the image forming apparatus 1 in a state where the front door 10 is open, the cartridge tray 20 is located outside the apparatus main body 2, and the process cartridge 100 is housed in the cartridge tray 20. Fig. 4 is a schematic cross-sectional view of the image forming apparatus 1 in a state where the front door 10 is open, the cartridge tray 20 is located outside the apparatus main body 2, and the yellow process cartridge 100Y has been removed from the cartridge tray 20. Figs. 2 to 4 show a cross section (XZ plane) approximately perpendicular to the Y direction as viewed from the non-drive side.

[0027] As shown in FIGS. 2 and 3 , the cartridge tray 20 is movable in the direction of arrow X1 (pushing direction) and the direction of arrow X2 (pulling direction). That is, the cartridge tray 20 is configured to be pulled out and pushed into the apparatus main body 2 by moving it in a substantially horizontal direction while the apparatus main body 2 is placed on a horizontal surface. Here, a state in which the front door 10 is open and the cartridge tray 20 is located outside the apparatus main body 2 (the state in FIG. 3 ) is referred to as the “outside state.” Also, a state in which the front door 10 is open and the cartridge tray 20 is located inside the apparatus main body 2 (the state in FIG. 2 ) is referred to as the “inside state.” In these outside and inside states, the photosensitive drums 101 and the intermediate transfer belt 51 are spaced apart. In this embodiment, the intermediate transfer unit 5 is movable together with the cartridge tray 20 in the direction of arrow X1 (pushing direction) and the direction of arrow X2 (pulling direction). In addition, in this embodiment, the image forming apparatus 1 is configured so that the fixing device 7 is moved in the Z1 direction (upward) when the cartridge tray 20 (and the intermediate transfer unit 5) is pulled out and pushed into the apparatus main body 2.

[0028] 4, the cartridge tray 20 has mounting portions 21 to which each process cartridge 100 can be removably attached in the outer state. Although only the mounting portion 21 for the yellow process cartridge 100Y is shown in FIG. 4, the cartridge tray 20 also has mounting portions 21 for the other process cartridges 100M, 100C, and 100K.

[0029] Then, when the process cartridge 100 is disposed in the mounting portion 21, the cartridge tray 20 is moved inside the apparatus main body 2, thereby moving the process cartridge 100 inside the apparatus main body 2. In this embodiment, when the front door 10 is closed, the intermediate transfer unit 5 is moved (raised) in the direction of arrow Z1 (upward) by a link mechanism (not shown). As a result, the intermediate transfer unit 5 moves to a position for image formation (a position where the photosensitive drum 101 and the intermediate transfer belt 51 contact each other). Also, in this embodiment, when the front door 10 is opened, the intermediate transfer unit 5 is moved (lowered) in the direction of arrow Z2 (downward) by the link mechanism. As a result, the intermediate transfer unit 5 moves to a position where the photosensitive drum 101 and the intermediate transfer belt 51 are separated from each other.

[0030] In this way, the cartridge tray 20 can move multiple process cartridges 100 together to a position inside the device main body 2 where image formation is possible, and to a position outside the device main body 2 where the process cartridges 100 can be removed.

[0031] <Overall structure of the process cartridge> Next, the overall structure of the process cartridge 100 in this embodiment will be described.

[0032] FIG. 5 is a cross-sectional view of the process cartridge 100, showing a cross section (XZ plane) substantially perpendicular to the Y direction as viewed from the non-drive side. FIG. 6 is an exploded perspective view of a drum unit 120 (described later) included in the process cartridge 100 (viewed from slightly above along the X1 direction, with the left side of the figure representing the non-drive side and the right side representing the drive side). FIG. 7 is an exploded perspective view of a development unit 140 included in the process cartridge 100 (viewed from slightly below along the X2 direction, with the left side of the figure representing the drive side and the right side representing the non-drive side). FIG. 8 is an assembled perspective view of the process cartridge 100 (viewed from slightly above along the X2 direction, with the left side of the figure representing the drive side and the right side representing the non-drive side). FIG. 9 is a perspective view of the process cartridge 100 (viewed from slightly above along the X2 direction, with the left side of the figure representing the drive side and the right side representing the non-drive side).

[0033] In this embodiment, the process cartridge 100 includes a drum unit 120 equipped with a photosensitive drum 101 and a charging roller 102, which serves as charging means acting on the photosensitive drum 101. The drum unit 120 may include, as processing means, not only the charging means but also a cleaning means for cleaning the surface of the photosensitive drum 101. The process cartridge 100 also includes, as processing means acting on the photosensitive drum 101, a developing unit (developing device) 140, which serves as developing means for developing an 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, which are yellow, magenta, cyan, and black, respectively, contain toner of each color. Within the apparatus main body 2, a laser scanner unit 11 is disposed above the four process cartridges 100Y, 100M, 100C, and 100K. The laser scanner unit 11 outputs a laser beam 12 corresponding to image information. The laser beam 12 passes through an exposure window 128 of the process cartridge 100 and scans and exposes the surface of the photosensitive drum 101. A more specific configuration of the process cartridge 100 will be described later.

[0034] It should be noted that with respect to the process cartridge 100, the drum unit 120, the developing unit 140, or these elements, a direction substantially parallel to the direction of the rotation axis A1 of the photosensitive drum 101 (see FIG. 8) is also referred to as the "longitudinal direction." The process cartridge 100 is used for image formation while being disposed so that the rotation axis A1 of the photosensitive drum 101 is substantially parallel to the Y direction. Therefore, the longitudinal direction is a direction substantially parallel to the Y direction.

[0035] <Drum unit configuration> As shown in FIGS. 6 and 8, the drum unit 120 includes a photosensitive drum 101, a charging roller 102, a drum frame 121, and the like. The charging roller 102 is rotatably supported at both longitudinal ends thereof by a driving-side charging bearing 126a and a non-driving-side charging bearing 127a. The driving-side charging bearing 126a and the non-driving-side charging bearing 127a are urged by pressure springs 126b and 127b, respectively, which are urging members serving as urging means, thereby pressing the charging roller 102 toward the photosensitive drum 101 (in the direction of arrow F in FIG. 5). The driving-side charging bearing 126a and the pressure spring 126b constitute a driving-side charging roller bearing unit 126. The non-driving-side charging bearing 127a and the pressure spring 127b constitute a non-driving-side charging roller bearing unit 127. Further, spacing members 129 and 130 are attached to both longitudinal ends of the charging roller 102, respectively, for spacing the charging roller 102 from the photosensitive drum 101 until, for example, a new process cartridge 100 is used.

[0036] The photosensitive drum 101 is rotatably supported at both longitudinal ends thereof by a driving-side cartridge cover member 122 and a non-moving-side cartridge cover member 123. The driving-side cartridge cover member 122 and the non-moving-side cartridge cover member 123 are each fixed to the drum frame 121 by any fixing means such as adhesive, welding, or fastening.

[0037] As shown in FIG. 8, a drum coupling member 125 serving as a drive input unit for transmitting a drive force to the photosensitive drum 101 is provided at the drive side end of the photosensitive drum 101 in the longitudinal direction. The drum coupling member 125 engages with a main body drum drive coupling 30 (FIGS. 3 and 4) serving as a drive output unit provided in the apparatus main body 2. A drive force from a drive motor (not shown) provided in the apparatus main body 2 is transmitted to the photosensitive drum 101 via the main body drum drive coupling 30 and the drum coupling member 125, causing the photosensitive drum 101 to rotate. A drum flange 124 is provided at the non-drive side end of the photosensitive drum 101 in the longitudinal direction. The photosensitive drum 101 is driven to rotate in the direction of arrow R1 (clockwise direction) in FIG. 5. The charging roller 102 comes into contact with the surface of the photosensitive drum 101 and is driven to rotate in the direction of arrow R6 (counterclockwise direction) in FIG. 5 as the photosensitive drum 101 rotates. The drive-side charging bearing 126a and the non-drive-side charging bearing 127a are supported by the drum frame 121 so that the charging roller 102 can contact the surface of the photosensitive drum 101 and rotate in response to the rotation of the photosensitive drum 101. The drive-side charging bearing 126a and the non-drive-side charging bearing 127a are supported by the drum frame 121 so that they can move toward and away from the photosensitive drum 101. The photosensitive drum 101 is also supported by the drum frame 121 with the drum coupling member 125 and the drum flange 124 rotatably supported by the drive-side cartridge cover member 122 and the non-drive-side cartridge cover member 123, respectively.

[0038] <Configuration of the development unit> As shown in FIGS. 5 and 7 , 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, and a developing frame 150. The developing frame 150 constitutes a developer container for accommodating developer (toner). The developing frame (developer container) 150 is composed of a first developing frame 151 and a second developing frame 152, which are frames (resin frames) formed from resin. In this embodiment, the first developing frame 151 and the second developing frame 152 are joined by ultrasonic welding. However, the first developing frame 151 and the second developing frame 152 can be fixed by any fixing means such as adhesive, welding, or fastening. The developing frame 150 forms a developing chamber 106 in which the developing roller 103 and the like are provided, and a developer storage chamber ("storage chamber") 107 that stores toner to be supplied to the developing roller 103. The developing chamber 106 and the storage chamber 107 are separated by a partition wall 167 that is formed from a part of the developing frame 150 (first developing frame 151).

[0039] First, the developing chamber 106 is provided with a developing roller 103 as a developer carrier (developing member) that carries toner and transports it to a developing section (developing nip) N3, which is an opposing portion (contact portion) with the photosensitive drum 101. The developing chamber 106 also is provided with a supply roller 104 as a supply member that supplies toner to the developing roller 103. The developing chamber 106 is also provided with a developing blade 156 as a regulating member. The developing chamber 106 is also provided with a sealing sheet 105 as a sealing member.

[0040] The developing roller 103 is a conductive rubber roller in which a conductive rubber layer is formed as an elastic layer on the outer periphery of a conductive core metal. In this embodiment, the developing roller 103 is driven to rotate in the direction of arrow R3 in FIG. 5 (counterclockwise direction) around a rotation axis B1 (see FIG. 10) that is substantially parallel to the longitudinal direction of the developing unit 140. In other words, the developing roller 103 is driven to rotate in a direction in which the moving direction of the surface of the photosensitive drum 101 and the moving direction of the surface of the developing roller 103 are forward directions in the developing portion N3.

[0041] The supply roller 104 is an elastic sponge roller with a foamed elastic layer formed on the outer periphery of a conductive core. In other words, the supply roller 104 has a foamed (porous) material on its surface (outer periphery). The supply roller 104 contacts the developing roller 104 with a predetermined penetration depth, and the foamed elastic layer constituting the surface of the supply roller 104 is compressed into a concave shape by the elastic layer of the developing roller 103, which has a higher hardness. The contact portion between the developing roller 103 and the supply roller 104, i.e., the region where the supply roller 104 is compressed by the developing roller 103 (compressed region), is also referred to as the "supply portion (supply nip) N4." In this embodiment, the supply roller 104 is driven to rotate in the direction of arrow R4 (counterclockwise) in FIG. 5 around a rotation axis B2 (see FIG. 10) that is substantially parallel to the longitudinal direction of the developing unit 140. That is, the supply roller 104 is rotationally driven in a direction opposite to the moving direction of the surface of the developing roller 103 at the supply portion N4 and the moving direction of the surface of the supply roller 104. Toner is supplied to the developing roller 103 by the supply roller 104 at the supply portion N4.

[0042] The developing blade 156 is disposed downstream of the supply unit N4 and upstream of the development unit N3 in the rotation direction of the developing roller 103 so as to contact the surface of the developing roller 103. In this embodiment, the developing blade 156 has a regulating portion 156b configured as an elastically deformable metal sheet member having a thickness of approximately 0.1 mm, and a support member 156a configured as a metal plate member (sheet metal) having a substantially L-shaped cross section (XZ plane) substantially perpendicular to the longitudinal direction. One end (fixed end) of the regulating portion 156b in the short direction substantially perpendicular to the longitudinal direction is fixed to the support member 156a. In this embodiment, the regulating portion 156b is fixed to the support member 156a by welding. However, the regulating portion 156b can be fixed to the support member 156a by any fixing means such as adhesive, welding, or fastening. The developing blade 156 is disposed so that the other end (free end) of the regulating portion 156b in the widthwise direction faces upstream in the direction of rotation of the developing roller 103. The regulating portion 156b abuts against the surface of the developing roller 103 on a side surface near the tip of the free end in the widthwise direction. The developing blade 156 regulates the layer thickness (coat amount) of toner supplied to the developing roller 103 by the supply roller 104. The developing blade 156 may have a function of imparting an electric charge to the toner. The developing blade 156 is held by the developing frame 150, as will be described later.

[0043] The sealing sheet 105 is disposed downstream of the developing unit N3 and upstream of the supply unit N4 in the rotation direction of the developing roller 103 so as to contact the surface of the developing roller 103. The sealing sheet 105 is made of a flexible sheet-like member. In this embodiment, the sealing sheet 105 is made of a polyphenylene sulfide (PPS) sheet-like member having a thickness of 0.06 mm. One end (fixed end) of the sealing sheet 105 in the lateral direction, which is approximately perpendicular to the longitudinal direction, is fixed to the developing frame 150 as described below. The sealing sheet 105 is disposed so that the other end (free end) in the lateral direction faces downstream in the rotation direction of the developing roller 103. The sealing sheet 105 contacts the surface of the developing roller 103 at a side near the tip of the free end in the lateral direction. The sealing sheet 105 prevents toner from leaking from the developing chamber 106 to the outside.

[0044] On the other hand, in this embodiment, the storage chamber 107 is disposed above the developing chamber 106, i.e., above the supply roller 104, and stores therein the toner to be supplied to the developing chamber 106. That is, in this embodiment, the developing chamber 106 is disposed below the storage chamber 107, and the supply roller 104 is disposed below the storage chamber 107. Note that this positional relationship between the developing chamber 106 and the storage chamber 107 is the positional relationship when the developing unit 140 is in the position when used for image formation in the image forming apparatus 1. A partition wall 167 separating the developing chamber 106 and the storage chamber 107 is formed with a supply opening 168 that communicates between the developing chamber 106 and the storage chamber 107 and allows the passage of toner supplied from the storage chamber 107 to the developing chamber 106. A transport member (developer transport member) 161 that transports the toner in the storage chamber 107 is disposed within the storage chamber 107. The transport member 161 also functions as an agitator (developer agitator) that agitates the toner in the storage chamber 107. In addition, the storage chamber 107 is provided with a remaining amount detection member (conductive sheet) 170 for detecting the remaining amount of developer in the development unit 140.

[0045] In a cross section (XZ plane) substantially perpendicular to the longitudinal direction of the developing unit 140, the storage chamber 107 roughly has a bottom surface 191, a front inner wall surface 192, a top surface 193, and a rear inner wall surface 194. The bottom surface 191 is formed by the inner wall surface of the partition wall 167. The front inner wall surface 192 is formed by an inner wall surface that extends in the vertical direction to connect the bottom surface 191 and the top surface 193 at the front side of the storage chamber 107. The top surface 193 is formed by an inner wall surface that extends 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 an inner wall surface that extends in the vertical direction to connect the top surface 193 and the bottom surface 191 at the rear side of the storage chamber 107. In this embodiment, a bottom surface 191 (partition wall 167), a top surface 193, and a rear inner wall surface 194 of the storage chamber 107 are formed by the first developing frame 151. In addition, in this embodiment, a front inner wall surface 192 of the storage chamber 107 and a bottom surface 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 in this embodiment, and may be configured by joining more frames together, or the portions configured by each frame in the developing frame 150 may differ from those in this embodiment.

[0046] Conveying member 161 has shaft 161a disposed substantially parallel to the longitudinal direction of developing unit 140, and two flexible conveying sheets (agitation sheets) 161b and 161c, which constitute a conveying section for conveying toner. Shaft 161a is disposed over substantially the entire area between the inner wall surfaces on both sides of storage chamber 107 in the longitudinal direction. Conveying sheets 161b and 161c are each sheet-like members extending over substantially the entire longitudinal area of ​​shaft 161a. One end (fixed end) of conveying sheets 161b and 161c in the lateral direction (direction of rotation radius) substantially perpendicular to the longitudinal direction is fixed to shaft 161a. Conveying sheets 161b and 161c are fixed to shaft 161a by any fixing means, such as adhesive, welding, or fastening. The other lateral ends of conveying sheets 161b and 161c are free ends. In this embodiment, the two conveying sheets 161b and 161c are fixed to the outer surface of the shaft 161a on opposite sides so as to extend in opposite directions toward the outside in the direction of the rotation radius of the shaft 161a. The conveying member 161 is driven to rotate in the direction of arrow R5 (counterclockwise) in FIG. 5 about a rotation axis O that is substantially parallel to the longitudinal direction of the developing unit 140. As the shaft 161a rotates in the direction of arrow R5 in FIG. 5, the conveying sheets 161b and 161c rotate in the same direction. As a result, the conveying member 161 conveys (agitates) the toner by the conveying sheets 161b and 161c. The conveying sheets 161b and 161c can be made of a polyester film, a polyphenylene sulfide film, a polycarbonate film, or the like, having an appropriate thickness (e.g., 300 μm).

[0047] The remaining amount detection member (conductive sheet) 170 is provided on the front inner wall surface 192 of the containing chamber 107. Details of the remaining amount detection configuration for detecting the remaining amount of developer in the developing unit 140 will be described later.

[0048] As shown in FIG. 7 , the developing roller 103 and the supply roller 104 are rotatably supported at both longitudinal ends thereof by a drive-side developing roller bearing 153 and a non-drive-side developing roller bearing 154. The drive-side developing roller bearing 153 and the non-drive-side developing roller bearing 154 are fixed to the developing frame 150 (first developing frame 151, second developing frame 152) by any fixing means such as adhesive bonding, welding, or fastening. In this embodiment, the developing blade 156 is attached to the developing frame 150 by fixing the support portion 156b to the developing frame 150 (first developing frame 151) by fixing screws 156c at two locations, one end side and the other end side, in the longitudinal direction. However, the developing blade 156 can be fixed to the developing frame 150 by any fixing means such as adhesive bonding, welding, or fastening. In this embodiment, the sealing sheet 105 is attached to the developing frame 150 (second developing frame 152) by double-sided tape as an attachment means. However, the sealing sheet 105 can be fixed to the developing frame 150 by any fixing means such as adhesion, welding, or fastening. The conveying member 161 (shaft 161a) is rotatably supported at both ends in the longitudinal direction by a drive-side developing bearing 153 and a non-drive-side developing bearing 154.

[0049] As shown in FIG. 7, a development drive input gear 159 serving as a drive transmission member for transmitting a driving force to the development unit 140 is provided at the drive side end in the longitudinal direction of the development unit 140. The development drive input gear 159 is provided with a development input coupling 159a serving as a drive input portion. The development input coupling 159a engages with a main body side development drive coupling 40 (FIGS. 3 and 4) serving as a drive output portion provided in the apparatus main body 2. Then, a driving force from a drive motor (not shown) provided in the apparatus main body 2 is input to the development unit 140 via the development drive input gear 159.

[0050] The driving force input to the developing unit 140 is transmitted from a developing drive input gear 159 to a developing roller gear 157 serving as a drive transmission member, thereby rotating the developing roller 103. The driving force input to the developing unit 140 is also transmitted from the developing drive input gear 159 to a supply roller gear 158 serving as a drive transmission member, thereby rotating the supply roller 104. The driving force input to the developing unit 140 is also transmitted from the developing drive input gear 159 to a conveying gear 160 serving 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 a drive-side developing bearing 153. A developing cover member 155 is provided at the drive-side end of the developing unit 140 in the longitudinal direction, supporting the developing drive input gear 159 and covering the developing drive gear 159, the developing roller gear 157, the supply roller gear 158, the conveying gear 160, etc.

[0051] <Assembling the drum unit and developing unit> Next, the assembly of the drum unit 120 and the developing unit 140 will be described.

[0052] As shown in FIG. 8, the drum unit 120 and the developing unit 140 are connected by a drive-side cartridge cover member 122 and a non-moving-side cartridge cover member 123 provided at both longitudinal ends of the process cartridge 100. The drive-side cartridge cover member 122 provided at the drive-side end of the process cartridge 100 in the longitudinal direction is provided with a developing unit support hole 122b for swingably (movably) supporting the developing unit 140. Similarly, the non-drive-side cartridge cover member 123 provided at the non-drive-side end of the process cartridge 100 in the longitudinal direction is provided with a developing unit support hole 123b for swingably supporting the developing unit 140. Furthermore, the drive-side cartridge cover member 122 and the non-moving-side cartridge cover member 123 are provided with drum support holes 122a, 123a, respectively, for rotatably supporting the photosensitive drum 101.

[0053] At the drive-side end of the process cartridge 100 in the longitudinal direction, the outer diameter portion of the cylindrical portion 155a of the developing cover member 155 is fitted into the developing unit support hole 122b of the drive-side cartridge cover member 122. At the non-drive-side end of the process cartridge 100 in the longitudinal direction, the outer diameter portion of the cylindrical portion (not shown) of the non-drive-side developing bearing 154 is fitted into the developing unit support hole 123b of the non-moving-side cartridge cover member 123. Furthermore, both longitudinal ends of the photosensitive drum 101 are fitted into the drum support hole 122a of the drive-side cartridge cover member 122 and the drum support hole 123a of the non-moving-side cartridge cover member 123. The drive-side cartridge cover member 122 and the non-moving-side cartridge cover member 123 are each fixed to the drum unit 120 (drum frame 121) by any fixing means such as screws or adhesive. As a result, the developing unit 140 is supported rotatably (pivotally and oscillateably) with respect to the drum unit 120 (photosensitive drum 101) by the driving-side cartridge cover member 122 and the non-moving-side cartridge cover member 123. Therefore, during image formation, the developing roller 103 can be positioned to act on the photosensitive drum 101 (in this embodiment, to come into contact with the photosensitive drum 101).

[0054] As shown in FIG. 9, the drum unit 120 and the developing unit 140 are assembled together as described above to form the process cartridge 100.

[0055] 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-moving-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 driving force is transmitted from the apparatus main body 2 on the swing axis A2. The developing unit 140 is supported rotatably with respect to the drum unit 120, centered on the swing axis A2.

[0056] <Configuration for detecting remaining amount in development unit> Next, a remaining amount detection configuration for detecting the remaining amount of developer in the developing unit 140 in this embodiment will be described.

[0057] FIG. 10 is a schematic perspective view of the developing unit 140 (showing a state viewed from slightly above along the X2 direction with the left side of the drawing being the drive side and the right side being the non-drive side). FIG. 11 is a schematic cross-sectional view (QQ cross-sectional view in FIG. 10) of the developing unit 140 at approximately the center in the longitudinal direction, showing a cross section (XZ plane) substantially perpendicular to the Y direction as viewed from the non-drive side. FIG. 12 is a perspective view of the second developing frame 152 (showing a state viewed from slightly above along the X2 direction with the left side of the drawing being the drive side and the right side being the non-drive side). FIG. 13(a) is a schematic front view of the second developing frame 152 as viewed along the X2 direction, i.e., from the developing roller 103 side, and FIG. 13(b) is a schematic side view of the second developing frame 152 as viewed from the non-drive side along the Y direction. 10 to 13 show a developing unit 140 according to this embodiment similar to that shown in Fig. 5 etc., but for simplicity, the developing unit 140 (or its elements) is shown having a configuration in which only one conveying sheet 161b is provided on a conveying member 161. The same applies to Figs. 15 to 17 described later.

[0058] A recess 163 extending along (substantially parallel to) the longitudinal direction of the second developing frame 152 is formed in a front inner wall surface 192 of the second developing frame 152 (accommodation chamber 107). The recess 163 has an upper surface (first surface) 163a of the inner wall surface of the accommodation chamber 107 and a lower surface (second surface) 163b of the inner wall surface of the accommodation chamber 107 located downstream of the supply opening 168 and upstream of the upper surface 163a in the rotation direction of the conveying member 161. In a cross section (XZ plane) substantially perpendicular to the longitudinal direction of the second developing frame 152, the upper surface 163a is configured as 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 rotation direction of the conveying member 161. Furthermore, in a cross section (XZ plane) substantially perpendicular to the longitudinal direction of the second developing frame 152, the lower surface 163b is configured as an inclined plane such that the distance from the rotation axis O of the conveying member 161 increases toward the downstream side in the rotation direction of the conveying member 161. The upper surface 163a and the lower surface 163b are connected by a bottom 163c of the recess 163. A conductive sheet 170, which is a conductive sheet-like member that constitutes the remaining amount detection member, is arranged on the upper surface 163a and the lower surface 163b, which are the two surfaces that form the recess 163.

[0059] In this embodiment, the second developing device frame 152 is provided with a first conductive sheet 171 and a second conductive sheet 172 as the conductive sheet 170. The first conductive sheet 171 is disposed on an upper surface 163a of the recess 163, and the second conductive sheet 172 is disposed on a lower surface 163b of the recess 163. The first conductive sheet 171 and the second conductive sheet 172 are disposed at a predetermined distance L without contacting each other. A further recess 162 is formed in the front inner wall surface 192 of the second developing device frame 152 (accommodation chamber 107) adjacent to and above the recess 163, extending along (substantially parallel to) the longitudinal direction of the second developing device frame 152. The further recess 162 has an apex 162a continuous with the upper surface 163a of the recess 163 and a slope 162b continuous with the apex 162a. In a cross section (XZ plane) substantially perpendicular to the longitudinal direction of the second developing frame 152, the inclined surface 162b is configured as an inclined plane such that the distance from the rotation axis O of the conveying member 161 increases toward the downstream side in the rotation direction of the conveying member 161. The first conductive sheet 171 is disposed continuously across two surfaces: the upper surface 163a of the recess 163 and the inclined surface 162b of another recess 162.

[0060] The portion of the first conductive sheet 171 that is disposed on the slope 162b of another recess 162 continues to the end of the second developing device frame 152 on the non-drive side in the longitudinal direction. The second conductive sheet 172 also continues on the lower surface 163b of the recess to the end of the second developing device frame 152 on the non-drive side in the longitudinal direction. The portion of the first conductive sheet 171 that is disposed on the upper surface 163a of the recess 163 and the portion of the second conductive sheet 172 that is disposed on the lower surface 163b of the recess 163 that faces this portion are disposed closely to each other with a predetermined distance L between them. In other words, the portions where the first conductive sheet 171 and the second conductive sheet 172 are closest to each other are limited to a predetermined range (detection range) W that extends symmetrically from the center of the second developing device frame 152 in the longitudinal direction toward both end sides. The space (hatched area in FIG. 11) sandwiched between the first conductive sheet 171 and the second conductive sheet 172 in the detection range W is the remaining amount detection unit 164.

[0061] The shape of the recess 163 in which the remaining amount detection portion 164 is provided is not limited to the shape in this embodiment. For example, any appropriate shape, such as a recess formed by a curved surface, can be used. In this embodiment, the first conductive sheet 171 is provided across two surfaces of the second developing frame 152 from the viewpoint of manufacturing, but it may be provided on only one surface, similar to the second conductive sheet 172.

[0062] In this embodiment, the first and second conductive sheets 171 and 172 are formed of conductive resin sheets. The thickness of the first and second conductive sheets 171 and 172 is 0.1 mm. The first and second conductive sheets 171 and 172 are made of resin sheets with a surface resistivity of 1.15 kΩ / sq or less. The first and second conductive sheets 171 and 172 are made of ethylene-vinyl acetate copolymer (EVA) resin with dispersed carbon black. The first and second conductive sheets 171 and 172 are attached to the second developing frame 152 by integrally molding the second developing frame 152 and the first and second conductive sheets 171 and 172 by insert molding. In this embodiment, 0.1 mm thick resin sheets were used for the first and second conductive sheets 171 and 172, taking into consideration factors such as the influence of frame deformation, transferability to the frame shape, and conductivity. However, the thickness of the resin sheets can be selected as appropriate. In this embodiment, EVA-based resin was used as the material for the first and second conductive sheets 171 and 172. However, polystyrene (PS), acrylonitrile butadiene styrene (ABS), polyphenylene oxide (PPO), and other resins may also be used. In this embodiment, resin sheets were used as the first and second conductive sheets 171 and 172 and attached to the developing device frame 150 by insert molding. However, the present invention is not limited to this configuration. For example, metal sheets may be used as the first and second conductive sheets 171 and 172, and these may be fixed (attached) to the developing device frame 150 by any fixing means, such as adhesive, welding, or fastening.

[0063] 14 is a schematic diagram showing a schematic circuit configuration for detecting the remaining amount of developer in the developing unit 140 in this embodiment. A method for measuring the capacitance of the remaining amount detection section 164 using the first and second conductive sheets 171 and 172 will be described. The apparatus main body 2 is provided with a voltage application device (power supply) 13 capable of applying an AC voltage (alternating current voltage) to the first conductive sheet 171 as a remaining amount detection bias (remaining amount detection voltage), and a remaining amount detection device (detection circuit) 14 electrically connected to the second conductive sheet 172. Electrical conduction between the first and second conductive sheets 171 and 172, which are arranged inside the second developing frame 152, and the voltage application device 13 and remaining amount detection device 14, which are arranged outside the second developing frame 152, may be achieved by any method. For example, by constructing a portion of the second developing frame 152 from a conductive resin, or by incorporating a conductive member into a portion of the second developing frame 152, it is possible to configure the second developing frame 152 so that the internal and external components are electrically connected.

[0064] In this embodiment, as shown in FIG. 13B, a first conductive resin contact 165a and a second conductive resin contact 165b are formed integrally with the second developing unit frame 152 by two-color molding at the end of the second developing unit frame 152 on the non-drive side in the longitudinal direction. The first conductive resin contact 165a and the second conductive resin contact 165b contact a first conductive sheet 171 and a second conductive sheet 172, respectively, thereby electrically connecting the internal and external components of the developing unit 140. The first conductive sheet 171 is connected to a voltage application device 13 provided in the apparatus main body 2 through the non-drive side developing unit bearing 154 (FIG. 7), and a voltage is applied to the first conductive sheet 171. The second conductive sheet 172 is connected to a remaining amount detection device 14 provided in the apparatus main body 2 through the non-drive side developing unit bearing 154 (FIG. 7), and a detection output corresponding to the remaining amount of developer in the developing unit 140 is obtained. The first and second conductive sheets 171, 172 function as electrode plates and form a capacitor inside the developing unit 140. In other words, the first conductive sheet 171 and the second conductive sheet 172 respectively constitute a first electrode and a second electrode as detection members. The first and second conductive sheets 171, 172 are aligned in the rotation direction of the conveying member 161 and extend along the rotation axis of the conveying member 161.

[0065] When an AC voltage is applied to the first conductive sheet 171, a current corresponding to the capacitance is induced in the remaining amount detection section 164, which is the space between the first conductive sheet 171 and the second conductive sheet 172. The angle between the first conductive sheet 171 and the second conductive sheet 172 in the portion forming the remaining amount detection section 164 is preferably set to 95° or more and 110° or less, at which point the capacitance can be stably measured, and in this embodiment, it is set to 100°. This capacitance changes depending on the amount of developer occupying the remaining amount detection section 164. The change in capacitance is input as a current value to the remaining amount detection device 14. The control section (control circuit) 15 provided in the device main body 2 can then sequentially calculate the remaining amount of developer in the development unit 140 based on the current value input to the remaining amount detection device 14. Furthermore, the control unit 15 can perform control so that information regarding the calculated remaining amount of developer is displayed on the display unit 16 provided in the apparatus main body 2 or on a display unit of an external device such as a personal computer connected to the image forming apparatus 1. The method of detecting the capacitance is not limited to the method described above. For example, the first conductive sheet 171 may be electrically connected to a remaining amount detection device, the second conductive sheet 172 may be electrically connected to a voltage application device, and an AC voltage may be applied to the second conductive sheet 172 to detect the capacitance.

[0066] The relationship between the operation of the transport member 161 and the operation of detecting the amount of developer in the remaining amount detection section 164 will be further described. As described above, the recessed space sandwiched between the first conductive sheet 171 and the second conductive sheet 172 in the detection range W is the remaining amount detection section 164. Then, the amount of developer transported into the remaining amount detection section 164 by the transport member 161 is detected, and the remaining amount of developer in the developing unit 140, that is, the "total remaining amount of developer" which is the sum of the amount of developer in the developer storage chamber and the amount of developer in the developing chamber, is calculated.

[0067] FIG. 15(a) is a schematic cross-sectional view (QQ cross-sectional view in FIG. 10) of developing unit 140 similar to FIG. 11, showing the conveying sheet 161b conveying conveyed developer (toner) T1 to remaining amount detection unit 164 and the conveyed developer T1 being detected by remaining amount detection unit 164. In this embodiment, the length of conveying sheet 161b in the short-side direction is set so that the leading edge of the free end of conveying sheet 161b can move while contacting at least a portion of bottom surface 191 and front inner wall surface 192 of storage chamber 107. At least a portion of front inner wall surface 192 typically includes at least a portion of lower surface 163b of recess 163. In other words, in a cross section (XZ plane) substantially perpendicular to the longitudinal direction of developing unit 140, the length of conveying sheet 161b in the short-side direction is longer than the distance from rotation axis (rotation center) O of conveying member 161 to at least a portion of bottom surface 191 and front inner wall surface 192. Therefore, even when the amount of developer in the developer storage chamber 107 is relatively small, as shown in FIG. 15(a), the conveying sheet 161b lifts up the developer and transports it to the remaining amount detection unit 164. In this way, the conveying member 161 is configured to move while its outer tip in the rotational radius direction contacts at least a portion of the partition wall 167. The remaining amount detection unit 164 is provided on the inner wall surface of the developer storage chamber 107 at a position where the tip of the conveying member 161 moves upward while contacting the partition wall 167 immediately after leaving the partition wall 167 when the developing unit 140 is in the position used for image formation in the image forming apparatus 1. In other words, when the developing unit 140 is in the position used for image formation in the image forming apparatus 1, at least a portion of the remaining amount detection unit 164 is located at a position where the developer lifted and transported by the conveying member 161 is supplied. In this embodiment, the conveying sheet 161b transports the developer while bending in the direction opposite to the rotational direction of the conveying member 161. At this time, since the developer (toner) is a dielectric, the capacitance between the first and second conductive sheets 171 and 172, which act as the plates of a capacitor, increases.

[0068] 15(b) is a schematic cross-sectional view (cross-sectional view taken along line QQ in FIG. 10) of developing unit 140 similar to that of FIG. 11, showing the state immediately after conveying sheet 161b has passed remaining amount detection section 164. Some of conveyed developer T1 is lifted above remaining amount detection section 164 by conveying sheet 161b, and some of conveyed developer T1 falls from remaining amount detection section 164 under its own weight, resulting in the distribution shown in the figure. As the developer, which is a dielectric, disappears (or decreases) from remaining amount detection section 164 in this way, the electrostatic capacitance between first and second conductive sheets 171 and 172 decreases.

[0069] As mentioned above, for simplicity, only one conveying sheet 161b is shown in FIG. 15, but in this embodiment, the behavior of the developer by each of the two conveying sheets 161b and 161c is substantially the same.

[0070] As developer is consumed during image formation, the amount of developer transported by the transport member 161 decreases. Therefore, the "time during which developer is present in the remaining amount detection portion 164," i.e., the "time during which the capacitance is increasing," also decreases. In this embodiment, the remaining amount detection device 14 is configured to be able to detect the remaining amount of developer in the development unit 140 by measuring this decreasing "time during which the capacitance is increasing."

[0071] Here, in order to improve the accuracy of detecting the remaining amount of developer in the developing unit 140, the developing unit 140 is required to have a configuration that makes the calculation result of the total remaining amount of developer more stable.

[0072] <Improved accuracy in detecting remaining developer amount> Next, a configuration for improving the accuracy of detecting the remaining amount of developer in the developing unit 140 in this embodiment will be described with reference to FIGS.

[0073] The developing unit 140 of this embodiment has the following three features.

[0074] First, remaining amount detection unit 164 is disposed downstream of supply opening 168 in the rotation direction (the direction of arrow R5 in the figure) of conveying member 161. That is, remaining amount detection unit 164 is disposed downstream of supply opening 168 in the movement direction of conveying sheet 161b (represented by the tip of the free end in the short direction), i.e., the direction of developer conveyance by conveying member 161. However, remaining amount detection unit 164 is disposed upstream of region I, which is an area on the inner wall surface of storage chamber 107 and is located on the opposite side of supply opening 168 with respect to rotation axis O of conveying member 161, in the rotation direction (the direction of arrow R5 in the figure). From the viewpoint of the developer conveyance efficiency to remaining amount detection unit 164 by conveying sheet 161b, remaining amount detection unit 164 is preferably disposed at a height equal to or lower than the height of horizontal line H passing through rotation axis O of conveying member 161. That is, preferably, at least a part of the remaining amount detection unit 164 is located at a height equal to or lower than the height of a horizontal line H passing through the rotation axis O of the conveying member 161 in the direction of gravity.

[0075] Second, the rotation direction of the conveying member 161 (the direction of the arrow R5 in the figure) and the rotation direction of the supply roller 104 (the direction of the arrow R4 in the figure) are the same.

[0076] Third, in the direction of gravity (the direction of arrow Z2 in the figure), the rotational axis B2 of the supply roller 104 is positioned at a height equal to or higher than the height of the rotational axis B1 of the developing roller 103. However, the rotational axis B2 of the supply roller 104 is typically positioned on the opposite side of the photosensitive drum 101 with respect to a vertical line passing through the rotational axis B1 of the developing roller 103. In other words, the rotational axis B2 of the supply roller 104 is positioned closer to the supply opening 168 than the rotational axis B1 of the developing roller 103.

[0077] The above-described positional relationship (operational relationship) only needs to be established when the developing unit 140 is in the position it is in when used for image formation in the image forming apparatus 1. The above-described positional relationship (operational relationship) is when viewed from a cross section that is approximately perpendicular to the longitudinal direction of the developing unit 140.

[0078] Here, a phenomenon that affects the accuracy of detecting the remaining amount of developer in the developing unit 140 will be described.

[0079] FIG. 16(a) is a schematic cross-sectional view of the vicinity of the supply roller 104 when the developer (toner) T2 is filled in the developing chamber 106 (showing a cross section (XZ plane) approximately perpendicular to the Y direction as viewed from the non-driven side). The supply roller 104 has a sleeve (foamed elastic layer) formed of a sponge (foamed elastic material) and holds the developer therein. Within the developing chamber 106, the developing roller 103 and the supply roller 104 contact each other along the longitudinal direction. The sponge of the supply roller 104, which has a higher hardness, is partially compressed, forming a supply portion (compressed region, supply nip) N4. In the rotation direction R4 of the supply roller 104, the sponge transitions from an uncompressed state to a compressed state near the upstream side of the supply portion N4. As a result, the developer inside the sponge is released from the sponge as indicated by arrow D in the figure. Meanwhile, in the vicinity of the downstream side of the supply portion N4, the sponge returns from a compressed state to an uncompressed state. Therefore, the developer around the sponge is absorbed by the sponge as shown by arrow E in the figure.

[0080] 16(b) is a schematic cross-sectional view of the vicinity of the supply roller 104 to explain the behavior of the developer in the developing chamber 106 accompanying the release and absorption of developer by the supply roller 104 described above (showing a cross section (XZ plane) substantially perpendicular to the Y direction as viewed from the non-driven side). In the rotation direction R4 of the supply roller 104, downstream of the supply portion N4, the developer decreases due to the absorption of the developer (arrow E) described above, so that the developer T2 to be filled in the developing chamber 106 becomes distributed as shown in the figure, and a void S occurs in the developing chamber 106. The volume of this void S varies depending on the amount of developer consumed according to the image to be formed, the state of the supply roller 104, and so it is difficult to estimate accurately.

[0081] As described above, remaining amount detection unit 164 detects the amount of developer transported by transport member 161 within storage chamber 107. Then, the total remaining amount of developer is calculated, which is the sum of the amount of developer within storage chamber 107 and the amount of developer within developing chamber 106. In other words, what is detected by remaining amount detection unit 164 is merely the "amount of developer transported within storage chamber 107," and does not include a parameter corresponding to the amount of developer within developing chamber 106. However, as described above, if there is gap S whose volume fluctuates within developing chamber 106, the amount of developer within developing chamber 106 will fluctuate, which will cause a discrepancy between the calculated total remaining amount of developer and the actual remaining amount of developer within developing unit 140, and this may reduce the accuracy of detecting the remaining amount of developer.

[0082] Next, the effects of the configuration of this embodiment will be described below. Figure 17 is a schematic cross-sectional view of the developing unit 140 similar to Figure 11, for explaining the effects of the configuration of this embodiment.

[0083] Due to the first feature described above, conveying sheet 161b passes through supply opening 168 before conveying conveyed developer T1 to remaining amount detection unit 164. Therefore, the amount of developer detected by remaining amount detection unit 164 is "the amount of developer conveyed by conveying member 161 according to the amount of developer remaining in storage chamber 104 after the gap in development chamber 106 is filled with developer." In other words, in the positional relationship described in the first feature described above, it is easy to ensure that gap S in development chamber 106 is filled with developer when the amount of developer is detected by remaining amount detection unit 164. Therefore, gap S, which can cause variations in the detection results of the developer amount by remaining amount detection unit 164, is reduced, and the amount of developer in development chamber 106 is easily stabilized. Therefore, the calculation result of the total remaining amount of developer, which is the sum of the amount of developer in storage chamber 107 and the amount of developer in development chamber 106, is stabilized, and the detection accuracy of the remaining amount of developer in development unit 140 is improved.

[0084] To further enhance the effect of the first feature, it is desirable that the gap S be present downstream of the supply opening 168 in the direction of developer transport by the transport member 161 (the direction along the rotation direction R5). This allows the developer transported by the transport member 161 to more smoothly fill the gap S, as indicated by arrow G in FIG. 17 . To achieve this, it is desirable that the developing unit 140 be equipped with the second feature described above. Due to the second feature described above, the positions at which the supply roller 104 releases (arrow D) and absorbs (arrow E) the developer are in the positional relationship shown in FIG. 17 . In other words, this makes it easier for the supply roller 104 to release the developer toward the upstream side of the supply opening 168 in the direction of developer transport by the transport member 161. Furthermore, the developer located downstream of the supply opening 168 in the direction of developer transport by the transport member 161 is more easily absorbed by the supply roller 104. As a result, a gap S is likely to occur downstream of the supply opening 168 in the direction in which the developer is transported by the transport member 161.

[0085] Furthermore, to more reliably obtain the effect of the second feature, it is preferable that the developing unit 140 be equipped with the third feature described above. Due to the third feature described above, the positional relationship between the positions at which the supply roller 104 releases (arrow D) and absorbs (arrow E) the developer is not reversed. In other words, the developer is more likely to be released from the supply roller 104 toward the downstream side of the supply opening 168, and the developer located upstream of the supply opening 168 is not more likely to be absorbed by the supply roller 104. This more reliably creates a situation in which the gap S is more likely to occur downstream of the supply opening 168 in the direction in which the developer is transported by the transport member 161.

[0086] In this embodiment, the developing unit 140 has the above-mentioned first to third features, and if it has the first feature, it can obtain the same corresponding effect as the above. For example, if the supply roller 104 has a foam elastic layer that forms the surface layer, it can further improve the effect of improving the detection accuracy of the remaining amount of developer in the developing unit 140 by having the above-mentioned second and third features.

[0087] As described above, according to this embodiment, the amount of developer can be detected by the remaining amount detection unit 164 in a state where the gaps in the developing chamber 106, which are a cause of variations in the amount of developer detected by the remaining amount detection unit 164, are filled with developer. This stabilizes the value of the total remaining amount of developer, which is the sum of the calculated amount of developer in the storage chamber 107 and the amount of developer in the developing chamber 107. Therefore, the accuracy of detecting the remaining amount of developer in the developing unit 140 is improved.

[0088] [others] Although the present invention has been described above with reference to specific embodiments, the present invention is not limited to the above-described embodiments.

[0089] In the above-described embodiment, the image forming apparatus is of a process cartridge type, but the present invention is not limited to this. The developing device may be fixed to the main body of the image forming apparatus. Furthermore, the developing device may be detachably attached to the main body of the image forming apparatus substantially independently. Furthermore, the image forming apparatus may be configured such that a developing device fixed to the main body or detachably attached to the main body of the image forming apparatus can be replenished with developer from a supply container. In this case, the supply container may be attached to the developing device during replenishment and removed before image formation begins, or the supply container may remain attached to the developing device during image formation.

[0090] Furthermore, in the above-described embodiment, the capacitance method is used as the developer remaining amount detection method, but the present invention is not limited to this. Any available method, such as a light transmission method, can be used as the developer remaining amount detection method. The light transmission method uses a light source that irradiates light onto a detection unit in the storage chamber and a light receiving unit that receives light that has passed through the inside of the developing device, and detects the amount of developer based on changes in the light receiving state of the light receiving unit (presence or absence of light reception, amount of light received, light reception time, etc.).

[0091] In the above-described embodiment, the supply roller is rotated in a direction in which the surface of the developing roller moves in the opposite direction to the surface of the supply roller at the portion facing (contacting) the developing roller, but the present invention is not limited to this. The supply roller may be rotated in a direction in which the surface of the developing roller moves in the forward direction to the surface of the supply roller at the portion facing (contacting) the developing roller. In this case, by providing the above-described features in accordance with the above-described embodiment, the same effects as those of the above-described embodiment can be obtained. [Explanation of symbols]

[0092] 1. Image forming device 2. Device body 100 Process cartridge 101 Photosensitive drum (image carrier) 103 Developing roller 104 Supply roller 106 Developing Room 107 Developer chamber 140 Development unit (developing device) 150 Developing frame 151 First developing frame 152 Second developing frame 161 Transporting member 161b Transport sheet 161c Transport sheet 164 Remaining amount detection unit (detection unit) 167 Bulkhead 168 Supply opening 170 Conductive sheet (detection element) 171 First conductive sheet 172 Second conductive sheet

Claims

1. A developing device used for image formation in an image forming apparatus, A developing room; a developer storage chamber separated from the developing chamber by a partition wall, communicating with the developing chamber through an opening provided in the partition wall, and storing a developer to be supplied to the developing chamber; a developing roller provided in the developing chamber and rotating to transport the developer to the image carrier; a supply roller provided in the developing chamber, contacting the developing roller and rotating to supply developer to the developing roller; a conveying member that is provided in the developer storage chamber and rotates to convey the developer in the developer storage chamber and supply the developer to the developing chamber through the opening; a detecting unit for detecting a remaining amount of developer in the developing device, the detecting unit being provided in the developer accommodating chamber and supplied with the developer transported by the transport member; and When the developing device is in a position when used for image formation in the image forming apparatus, the developing chamber is provided below the developer accommodating chamber, the detection unit is disposed downstream of the opening in the rotation direction of the transport member and upstream of a region of an inner wall surface of the developer accommodating chamber that is on the opposite side of the opening with respect to a rotation axis of the transport member, The developing device according to claim 1, wherein the supply roller rotates in the same direction as the conveying member.

2. 2. The developing device according to claim 1, wherein when the developing device is in the posture, the rotation axis of the supply roller is positioned at a height equal to or higher than the height of the rotation axis of the developing roller in the direction of gravity.

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

4. The developing device according to claim 1 or 2, wherein when the developing device is in the posture, at least a portion of the detection portion is positioned at a position where the developer lifted and transported by the transport member is supplied.

5. 5. The developing device according to claim 4, wherein when the developing device is in the posture, at least a portion of the detection portion is located at a height equal to or lower than the height of a horizontal line passing through the rotation axis of the conveying member in the direction of gravity.

6. the conveying member is configured to move while an outer tip end of the conveying member in a rotational radial direction contacts at least a part of the partition wall, The developing device according to claim 1 or 2, characterized in that the detection portion is provided on the inner wall surface of the developer storage chamber at a position where, when the developing device takes the posture, the tip of the transport member moves upward while contacting the inner wall surface immediately after leaving the partition wall.

7. 7. The developing device according to claim 6, wherein when the developing device is in the posture, at least a portion of the detection portion is located at a height equal to or lower than the height of a horizontal line passing through the rotation axis of the conveying member in the direction of gravity.

8. 3. The developing device according to claim 1, wherein the detecting portion is provided in a recessed portion that is recessed toward the outside of the developer containing chamber.

9. 3. The developing device according to claim 1, wherein the detecting portion is provided with a detecting member for detecting an electrostatic capacity corresponding to an amount of developer supplied to the detecting portion.

10. 10. The developing device according to claim 9, further comprising a first electrode and a second electrode as the detection member, the first electrode and the second electrode being aligned in the rotational direction of the transport member and each extending along the rotational axis of the transport member.

11. the first electrode is provided on a first surface of an inner wall surface of the developer storage chamber, the second electrode is provided on a second surface of an inner wall surface of the developer accommodating chamber, the second surface being located downstream of the opening and upstream of the first surface in a rotation direction of the conveying member, 11. The developing device according to claim 10, wherein, in a cross section perpendicular to the rotation axis of the transport member, the first surface is inclined so that the distance from the rotation axis of the transport member decreases toward the downstream side in the rotation direction of the transport member, and the second surface is inclined so that the distance from the rotation axis of the transport member increases toward the downstream side in the rotation direction of the transport member.

Images