JP2011022396A - Developing device, process cartridge and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce developer remaining in a position on an internal wall of a developer storage chamber corresponding to the lengthwise middle of a developer conveying member. <P>SOLUTION: A developing unit 4 includes: a toner storage chamber 18a; a developing chamber 18b; an opening 27 between the toner storage chamber 18a and developing chamber 18b; a toner conveying member 22 in the toner storage chamber 18a; and a developing roller 17 in the developing chamber 18b. In the internal wall of the toner storage chamber 18a, a boundary p is set as a reference, which is located on a downstream side of the lowest part q in the rotating direction of the toner conveying member 22, and where an angle of the internal wall with respect to a horizontal surface changes to an angle of repose of developer or greater from an angle less than the angle of repose thereof. The amount of deformation of the toner conveying member 22 which is deformed while being in contact with the internal wall is set larger at both lengthwise ends 22y than that at the lengthwise middle 22x on an upstream side of the boundary p in the rotating direction of the toner conveying member 22, and the amount of deformation is substantially uniform in a longitudinal direction on a downstream side of the boundary p in the rotating direction of the toner conveying member 22. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a developing device, a process cartridge, and an image forming apparatus used in an electrophotographic image forming apparatus.

  Here, the electrophotographic image forming apparatus (hereinafter also simply referred to as “image forming apparatus”) forms an image on a recording material (recording medium) using an electrophotographic image forming system. Examples of the image forming apparatus include a copying machine, a printer (laser beam printer, LED printer, etc.), a facsimile machine, a word processor, and a multifunction machine (multifunction printer) thereof.

  The developing device is a device for visualizing an electrostatic image on an image carrier such as an electrophotographic photosensitive member using a developer.

  The process cartridge is a cartridge in which an electrophotographic photosensitive member and a charging unit, a developing unit, or a cleaning unit serving as a process unit that acts on the electrophotographic photosensitive member are integrated into a cartridge that can be attached to and detached from the image forming apparatus main body. It is. Alternatively, the process cartridge integrally forms an electrophotographic photosensitive member and at least one of charging means, developing means, and cleaning means as process means acting on the electrophotographic photosensitive member, with respect to the image forming apparatus main body. Can be attached and detached. Alternatively, the process cartridge is a cartridge in which the electrophotographic photosensitive member and at least the developing unit are integrated into a cartridge, which can be attached to and detached from the image forming apparatus main body.

  In an image forming apparatus such as a printer using an electrophotographic image forming method (electrophotographic process), an electrophotographic photosensitive member (hereinafter also simply referred to as “photosensitive member”) as an image carrier is uniformly charged. Next, an electrostatic image is formed on the photosensitive member by selectively exposing the charged photosensitive member. Next, the electrostatic image formed on the photoconductor is visualized as a toner image with developer toner. The toner image formed on the photoconductor is transferred to a recording material such as recording paper or a plastic sheet, and the toner image is applied to the recording material by applying heat or pressure to the toner image transferred onto the recording material. Image recording is performed by fixing.

  Such an image forming apparatus generally requires replenishment of developer and maintenance of various process means. In order to facilitate this developer replenishment work and maintenance of various process means, the photoconductor, charging device, developing device, cleaning device, etc. can be combined into a cartridge inside the frame and attached to the main body of the image forming apparatus. It has been put to practical use as a simple process cartridge. According to the process cartridge system, an image forming apparatus with excellent usability can be provided.

  The developing device inside the process cartridge generally includes a developer carrier that supplies a developer to the photosensitive member, a developer chamber that includes a developer supplier that supplies the developer to the developer carrier, and the development chamber. A developer storage chamber for storing the developer supplied to the chamber. As an invention relating to an image forming apparatus provided with a developing device having such a developing chamber and a developer accommodating chamber, there is an invention described in Patent Document 1. In the image forming apparatus described in Patent Document 1, the photosensitive member is disposed below the intermediate transfer member or the recording material carrier. In this case, the developer needs to be supplied against the gravity from the developer storage chamber located below the developing chamber to the developing chamber. The developing unit 60 provided in the image forming apparatus described in Patent Document 1 will be described below with reference to FIG. In the developing unit 60 of Patent Document 1, as shown in FIG. 6C, in order to transport the developer from the developer accommodating chamber 61 to the developing chamber 62 disposed above the developer accommodating chamber 61, A flexible sheet member 63b is attached to the tip of the stirring member 63a for stirring the developer.

JP 2003-173083 A

  However, in the developing unit 60 of Patent Document 1, the leading end of the sheet member 63b rotates while sliding in a uniform state (a plate-like state) in the longitudinal direction on the inner wall surface of the developer accommodating chamber 61. Problems arise. That is, when the developer in the developer storage chamber 61 becomes small, the developer may not be placed on the sheet member 63b and remain without being conveyed. As a result, the remaining amount of toner is not conveyed to the supply roller 66, and particularly when a solid image is output in the second half of the endurance, even if a desired density is obtained, the leading edge of the image starts from the center of the image. In this case, a thin density occurs (so-called poor image density tracking).

  In view of the above circumstances, the present invention can reduce the developer remaining without being pumped up at the position of the inner wall surface of the developer storage chamber corresponding to the central portion in the longitudinal direction of the developer transport member. It is an issue to provide.

  In order to solve the above-described problems, a developing device according to the present invention divides a developer storage chamber for storing a developer, a development chamber adjacent to the developer storage chamber, the developer storage chamber, and the development chamber. A partition wall, an opening penetrating the partition wall, and an inside of the developer storage chamber are disposed, and the developer is conveyed from the developer storage chamber to the development chamber through the opening while rotating. And a developer carrying member disposed inside the developing chamber and carrying the developer while rotating, the inner wall surface of the developer containing chamber has the highest height. When the boundary point where the angle with respect to the horizontal plane changes from less than the repose angle of the developer to more than the repose angle at the downstream side of the rotation direction of the developer transport member from the lowest lowest point is defined as the development point The agent conveying member deforms while abutting against the inner wall surface The amount of deformation is set larger at both ends in the longitudinal direction than at the central portion in the longitudinal direction on the upstream side in the rotation direction of the developer transporting member relative to the boundary portion, and the developer transport is greater than the boundary portion. On the downstream side of the rotation direction of the member, the length is set substantially uniform in the longitudinal direction.

  As described above, according to the present invention, the deformation amount of the developer conveying member deformed while contacting the inner wall surface is longer than the central portion in the longitudinal direction on the upstream side in the rotation direction of the developer conveying member from the boundary portion. Also, both ends are set larger. Accordingly, the toner inside the developer storage chamber is drawn from the center side to the both end sides in the longitudinal direction of the developer transport member. The deformation amount of the developer conveying member that is deformed while contacting the inner wall surface is set to be substantially uniform in the longitudinal direction on the downstream side of the rotation direction of the developer conveying member from the boundary portion. Accordingly, the developer is prevented from dropping in the direction of gravity, and the developer is efficiently conveyed to the opening. As a result, the developer remaining without being pumped is reduced at the position of the inner wall surface of the developer storage chamber corresponding to the central portion in the longitudinal direction of the developer transport member. For this reason, when the amount of developer is reduced in the developer storage chamber, the image follow-up defect that decreases in density from the center to the rear end of the image is suppressed, and the development inside the developer storage chamber is suppressed. The agent is used without waste.

1 is a cross-sectional view illustrating a configuration of a developing device, a process cartridge, and an image forming apparatus according to an embodiment of the invention. FIG. 3 is a cross-sectional view of the process cartridge as viewed in the axial direction of the photosensitive drum. It is sectional drawing etc. which follow the XX line of FIG. 2 which shows the structure of a conveyance support shaft and a convex part. FIG. 3 is a cross-sectional view of the configuration of the first opening and the second opening as seen from the direction α in FIG. It is sectional drawing etc. which show the structure of the process cartridge which concerns on a 1st comparative example. It is sectional drawing etc. which show the structure of the process cartridge which concerns on a 2nd comparative example.

  Hereinafter, exemplary embodiments of the present invention will be described in detail by way of example. However, since the dimensions, materials, shapes, relative positions, etc. of the components described in this embodiment are appropriately changed according to the configuration of the mechanism to which the present invention is applied and various conditions, there are particularly specific descriptions. As long as there is not, it is not the meaning which limits the scope of the present invention only to them.

  FIG. 1 is a cross-sectional view illustrating configurations of a developing unit 4, a process cartridge 7, and an image forming apparatus 100 according to an embodiment of the present invention. The overall configuration of the electrophotographic image forming apparatus, that is, the image forming apparatus 100 will be described below with reference to FIG. An image forming apparatus 100 shown in FIG. 1 is a full-color laser printer that employs an inline method and an intermediate transfer method. The image forming apparatus 100 can form a full-color image on a recording material (for example, recording paper, plastic sheet, cloth, etc.) according to the image information. The image forming apparatus 100 includes an image forming apparatus main body (hereinafter simply referred to as “apparatus main body”) 100A. The image information is transferred from an image reading apparatus connected to the apparatus main body 100A or a host device such as a personal computer connected to the apparatus main body 100A so as to be communicable to a controller which is a “control unit” (not shown) inside the apparatus main body 100A. Entered.

  The image forming apparatus 100 includes, as a plurality of image forming units, a first image forming unit SY for forming an image of each color of yellow (Y), magenta (M), cyan (C), and black (K), respectively. A second image forming unit SM, a third image forming unit SC, and a fourth image forming unit SK; The first to fourth image forming units SY to SK are arranged in a line in an oblique direction intersecting the vertical direction. The configurations and operations of the first to fourth image forming units SY to SK are substantially the same except that the colors of the images to be formed are different. Therefore, in the following, unless there is a particular distinction, the subscripts Y, M, C, and K given to the reference numerals to indicate that they are elements provided for any color are omitted, and generally The image forming unit S will be described. Similarly for photoconductor drums 1Y to 1K, charging rollers 2Y to 2K, developing units 4Y to 4K, cleaning members 6Y to 6K, process cartridges 7Y to 7K, and primary transfer rollers 8Y to 8K described below, 4, 6, 7, and 8 will be collectively described.

  The image forming apparatus 100 includes a photosensitive drum 1 as an “electrophotographic photosensitive member” that is a “plurality”, that is, four “image carriers”. Since the first to fourth image forming units SY, SM, SC, and SK are arranged side by side in an oblique direction that intersects the vertical direction, the photosensitive drum 1 is arranged in an oblique direction that intersects the vertical direction. Will be. The photosensitive drum 1 is rotationally driven by an unillustrated driving means (driving source) in the direction of arrow A (clockwise). Around the photosensitive drum 1, a charging roller 2 as a charging means for uniformly charging the surface of the photosensitive drum 1, a laser is irradiated based on image information, and an electrostatic image (electrostatic) is formed on the photosensitive drum 1. A scanner unit (exposure device) 3 is disposed as exposure means for forming a (latent image). Further, around the photosensitive drum 1, a developing unit (developing device) 4 as developing means for developing an electrostatic image as a toner image, toner remaining on the surface of the photosensitive drum 1 after transfer (transfer residual toner) A cleaning member 6 is disposed as a cleaning means for removing water. Further, an intermediate transfer belt 5 as an intermediate transfer body for transferring the toner image on the photosensitive drum 1 to the recording material 12 is disposed opposite to the four photosensitive drums 1. In the rotation direction of the photosensitive drum 1, the charging position by the charging roller 2, the exposure position by the scanner unit 3, the development position by the development unit 4, the transfer position of the toner image to the intermediate transfer belt 5, and the cleaning position by the cleaning member 6 are They are provided in this order.

  In the developing unit 4, non-magnetic one-component toner (hereinafter simply referred to as “toner”) as “non-magnetic one-component developer” which is “developer” is used. The developing unit 4 performs reverse development by bringing a developing roller (described later) as a “developer carrier” into contact with the photosensitive drum 1. That is, the developing unit 4 is a portion (image portion, exposure portion) in which the charge is attenuated by exposure on the photosensitive drum 1 with toner charged to the same polarity (negative polarity in this embodiment) as the charging polarity of the photosensitive drum 1. ) To develop the electrostatic image.

  The photosensitive drum 1 and the charging roller 2, the developing unit 4, and the cleaning member 6 as process means acting on the photosensitive drum 1 are integrally formed into a cartridge to form a process cartridge 7. The process cartridge 7 can be attached to and detached from the apparatus main body 100A through mounting means such as a mounting guide and a positioning member provided in the apparatus main body 100A. The process cartridges 7 for the respective colors have the same shape, and the process cartridges 7 for the respective colors have yellow (Y), magenta (M), cyan (C), and black (K) colors, respectively. Toner is contained.

  The intermediate transfer belt 5 formed of an endless belt as an intermediate transfer member abuts on all the photosensitive drums 1 and circulates (rotates) in the direction of arrow B (counterclockwise). The intermediate transfer belt 5 is wound around a driving roller 51, a secondary transfer counter roller 52, and a driven roller 53 as a plurality of support members.

  On the inner peripheral surface side of the intermediate transfer belt 5, four primary transfer rollers 8 as primary transfer means are arranged in parallel so as to face the respective photosensitive drums 1. The primary transfer roller 8 presses the intermediate transfer belt 5 toward the photosensitive drum 1 to form a primary transfer portion N1 where the intermediate transfer belt 5 and the photosensitive drum 1 abut. A bias having a polarity opposite to the normal charging polarity of the toner is applied to the primary transfer roller 8 from a primary transfer bias power source (high voltage power source) as a primary transfer bias applying unit (not shown). As a result, the toner image on the photosensitive drum 1 is transferred (primary transfer) onto the intermediate transfer belt 5.

  A secondary transfer roller 9 as a secondary transfer unit is disposed at a position facing the secondary transfer counter roller 52 on the outer peripheral surface side of the intermediate transfer belt 5. The secondary transfer roller 9 is in pressure contact with the secondary transfer counter roller 52 via the intermediate transfer belt 5 to form a secondary transfer portion N2 where the intermediate transfer belt 5 and the secondary transfer roller 9 are in contact with each other. Then, a bias having a polarity opposite to the normal charging polarity of the toner is applied to the secondary transfer roller 9 from a secondary transfer bias power source (high voltage power source) as a secondary transfer bias applying unit (not shown). As a result, the toner image on the intermediate transfer belt 5 is transferred (secondary transfer) to the recording material 12. The primary transfer roller 8 and the secondary transfer roller 9 have the same configuration.

  At the time of image formation, first, the surface of the photosensitive drum 1 is uniformly charged by the charging roller 2. Next, the surface of the charged photosensitive drum 1 is scanned and exposed by laser light corresponding to the image information emitted from the scanner unit 3, and an electrostatic image according to the image information is formed on the photosensitive drum 1. Next, the electrostatic image formed on the photosensitive drum 1 is developed as a toner image by the developing unit 4. The toner image formed on the photosensitive drum 1 is transferred (primary transfer) onto the intermediate transfer belt 5 by the action of the primary transfer roller 8.

  For example, at the time of full-color image formation, the above-described process is sequentially performed in the first to fourth image forming units SY to SK, and the toner images of the respective colors are then superimposed and primarily transferred onto the intermediate transfer belt 5. The Thereafter, the recording material 12 is conveyed to the secondary transfer portion N2 in synchronization with the movement of the intermediate transfer belt 5, and the operation of the secondary transfer roller 9 that is in contact with the intermediate transfer belt 5 through the recording material 12 is performed. Thus, the four-color toner images on the intermediate transfer belt 5 are secondarily transferred onto the recording material 12 at once. The recording material 12 onto which the toner image has been transferred is conveyed to a fixing device 10 as a fixing unit. The toner image is fixed on the recording material 12 by applying heat and pressure to the recording material 12 in the fixing device 10. Further, the primary transfer residual toner remaining on the photosensitive drum 1 after the primary transfer process is removed and collected by the cleaning member 6. The secondary transfer residual toner remaining on the intermediate transfer belt 5 after the secondary transfer process is cleaned by the intermediate transfer belt cleaning device 11. Note that the image forming apparatus 100 can form a single-color or multi-color image using only a desired single or some (not all) image forming units.

  FIG. 2 is a cross-sectional view of the process cartridge 7 as viewed in the axial direction of the photosensitive drum 1. In the description of the configuration and operation of the developing unit 4 and the process cartridge 7 in the embodiment, including the description relating to FIG. 2, the terms representing the directions such as up, down, vertical, and horizontal are generally used unless otherwise specified. The direction when viewed in the state of use. That is, the normal use state of the developing unit 4 or the process cartridge 7 is a state in which the developing unit 4 or the process cartridge 7 can be properly attached to the properly disposed apparatus main body 100A and used for an image forming operation. The configuration and operation of the process cartridge 7 for each color are substantially the same except for the type (color) of the developer stored therein. The process cartridge 7 includes a photosensitive unit 13 including a photosensitive drum 1 that is an “image carrier” and a developing unit 4 that includes a developing roller 17 that is a “developer carrier”.

  The photoconductor unit 13 has a cleaning frame 14 as a frame that supports various elements inside the photoconductor unit 13. The photosensitive drum 1 is rotatably attached to the cleaning frame 14 via a bearing (not shown). The photosensitive drum 1 is rotationally driven in the direction of arrow A (clockwise) according to the image forming operation by transmitting the driving force of a driving motor (not shown) as a driving means (driving source) to the photosensitive unit 13. The As the photosensitive drum 1 which is the center of the image forming process, a photosensitive drum 1 is used in which an outer peripheral surface of an aluminum cylinder is coated with a functional undercoat layer, a carrier generation layer, and a carrier transfer layer in this order. . The photosensitive drum 1 rotates at a rotation speed of 200 mm / sec.

  Further, the cleaning unit 6 and the charging roller 2 are disposed in the photosensitive unit 13 so as to come into contact with the peripheral surface of the photosensitive drum 1. The transfer residual toner removed from the surface of the photosensitive drum 1 by the cleaning member 6 falls into the cleaning frame 14 and is stored. The charging roller 2 as charging means is driven to rotate by bringing the roller portion of conductive rubber into pressure contact with the photosensitive drum 1. Here, as a charging step, a DC voltage of −1100 V is applied to the core of the charging roller 2 with respect to the photosensitive drum 1, whereby the surface potential of the photosensitive drum 1 becomes about −550 V. Such dark part potential (Vd) is formed. The spot pattern of the laser beam emitted in response to the image data by the laser beam from the scanner unit 3 exposes the photosensitive drum 1, and the exposed portion is charged on the surface by the carrier from the carrier generation layer. Disappears and the potential drops. As a result, an electrostatic latent image is formed on the photosensitive drum 1 where the exposed portion has a bright portion potential Vl = −100V and the unexposed portion has a dark portion potential Vd = −550V.

  On the other hand, the developing unit 4 includes a developing frame 18 as a frame that supports various elements inside the developing unit 4. Inside the developing frame 18, a toner conveying member 22 that is a “developer conveying member”, a developing roller 17 that is a “developer carrying member”, and a supply roller 20 that is a “developer supplying body” are arranged. .

  The developing roller 17 as a “developer carrying member” is in contact with the photosensitive drum 1 in the developing unit 4 and rotates in the direction of arrow D (counterclockwise), thereby electrostatically charging the surface of the photosensitive drum 1. A roller capable of developing an image. The developing roller 17 and the photosensitive drum 1 rotate so that the surfaces of the developing roller 17 and the photosensitive drum 1 move in the same direction (in this embodiment, the direction from the bottom to the top) in the facing portion (contact portion). The developing roller 17 is rotatably supported on the developing frame 18 via development side plates 19 (19R, 19L) at both ends in the longitudinal direction (rotation axis direction). Here, the development side plates 19 (19R, 19L) are respectively attached to both side portions of the development frame 18. Although the developing roller 17 is disposed in contact with the photosensitive drum 1, the developing roller 17 may be disposed close to the photosensitive drum 1 at a predetermined interval. In FIG. 2, only the right development side plate 19R is actually shown. A right developing side plate 19R is arranged on one end side in the longitudinal direction of the developing roller 17, and a left developing side plate 19L is arranged on the other end side in the longitudinal direction of the developing roller 17.

  With respect to the DC bias applied to the developing roller 17 = −350 V, the toner charged negatively by frictional charging is transferred only to the bright portion potential portion from the potential difference in the developing portion in contact with the photosensitive drum 1. Visualize the electrostatic latent image. The toner used is a non-magnetic one-component toner and is a so-called reversal developing system that transfers the toner to an exposed portion. The developing roller 17 is a so-called elastic developing roller having an elastic layer on a cored bar. About 3 mm of a first layer (base layer) made of solid rubber in which carbon is dispersed in silicone rubber is formed on a stainless steel core having an outer diameter of 6 mm. Further, as the second layer (surface layer), a urethane layer whose resistance is adjusted by a conductive agent is formed to a thickness of about 10 μm. The rotation speed of the developing roller 17 is set to be about 1.3 times faster than the rotation speed of the photosensitive drum 1.

  The supply roller 20 as a “developer supply body” rotates in the direction of arrow E (counterclockwise) so as to contact the peripheral surface of the development roller 17 inside the development unit 4. That is, the supply roller 20 and the developing roller 17 rotate so that the surfaces of the supply roller 20 and the developing roller 17 move in opposite directions at the opposing portion (contact portion). The supply roller 20 supplies toner onto the developing roller 17 and also acts to peel off toner remaining on the developing roller 17 without being used for development from the developing roller 17.

  The supply roller 20 is formed of an open-cell foam (hereinafter referred to as a foam layer) on the outer periphery of the conductive metal core. The foam layer of the supply roller 20 plays a role of peeling off the toner that has not contributed to the supply of toner to the developing roller 17 and development. The toner on the developing roller 17 is mechanically removed by rubbing the edge of the foam cell.

  The supply roller 20 is an elastic sponge roller having an outer diameter of φ16 mm, in which a polyurethane foam having a foamed skeleton structure and a relatively low hardness is formed 5.5 mm (cell diameter of 300 to 450 μm) on a core metal having an outer diameter of φ5 mm. The supply roller 20 is composed of a foam having a continuous foaming property, so that the supply roller 20 is brought into contact with the developing roller 17 without applying excessive pressure, and is consumed during supply of toner onto the developing roller 17 and development with appropriate irregularities on the surface of the foam. The remaining image is removed without being removed. The scraping property of this cell structure is not limited to urethane foam. For example, as the material of the foam layer, other commonly used rubbers such as NBR rubber (NBR: nitrile rubber), silicone rubber, acrylic rubber, hydrin rubber, ethylene propylene rubber (EPDM) can be used. Alternatively, as the material for the foamed layer, other commonly used rubbers such as chloroprene rubber, styrene butadiene rubber, isoprene rubber, acrylonitrile butadiene rubber, and composite mixtures thereof can be used. For adjusting the resistance of the foam layer, a known ionic conductive agent, inorganic fine particles, carbon black, or the like can be dispersed as appropriate.

  In addition, in order to assist the supply of toner to the developing roller 17, a bias that urges the toner from the supply roller 20 side to the developing roller 17 side may be applied to the supply roller 20. By applying a bias for biasing the negatively charged toner to the developing roller 17 side, the amount of toner carried on the developing roller 17 before the developing blade 21 can be increased. Further, the toner density on the developing roller 17 is likely to increase due to the bias, and even when the surface roughness of the developing roller 17 is low, a uniform toner density can be easily obtained. In addition, the supply roller 20 rotates in the reverse direction at the portion in contact with the developing roller 17 (so-called counter rotation). The surface rotation speed was 0.85 times the surface rotation speed of the developing roller 17.

  Further, the developing unit 4 is a developer as a “developer amount regulating member” that regulates the layer thickness of the toner supplied onto the developing roller 17 by the supply roller 20 so as to come into contact with the peripheral surface of the developing roller 17. A blade 21 is arranged. The developing blade 21 abuts the developing roller 17 on the downstream side of the supply roller 20 with respect to the rotation direction of the developing roller 17, faces development, and regulates the amount of developer and applies electric charge. The developing blade 21 is made of a thin metal plate and forms contact pressure by utilizing the spring elasticity of the thin plate so that the surface of the thin metal plate comes into contact with and abuts against the toner and the developing roller 17. As the material of the metal thin plate, a thin plate such as stainless steel or phosphor bronze can be used, but a phosphor bronze thin plate having a thickness of 0.1 mm was used. The toner is triboelectrically charged by being rubbed with the developing blade 21 and the developing roller 17 to be charged, and at the same time, the layer thickness is regulated. A predetermined voltage (−550 V) is supplied to the developing blade 21 from a blade bias power supply (not shown).

  The development unit 4 described above has a development side plate 19, that is, a right development side plate 19R and a left development side plate 19L on both ends in the longitudinal direction. The right developing side plate 19R has a hole 19Ra, and the left developing side plate 19L has a hole 19La. On the other hand, a coupling shaft 23, that is, a right coupling shaft 23R and a left coupling shaft 23L are attached to the photoreceptor unit 13. The right coupling shaft 23R is inserted into the hole 19Ra, the left coupling shaft 23L is inserted into the hole 19La, and the developing unit 4 is coupled to the photosensitive unit 13 so as to be swingable about the coupling shaft 23. Has been. Further, at the time of image formation, the developing unit 4 is urged by a developing unit pressure spring 24 as “biasing means” and rotates around the coupling shaft 23 in the direction of arrow F (clockwise). As a result, the developing roller 17 comes into contact with the photosensitive drum 1. In FIG. 2, only the right developing side plate 19R, the hole 19Ra, and the right coupling shaft 23R are actually shown. The right developing side plate 19R, the hole 19Ra, and the right coupling shaft 23R are arranged on one end side in the longitudinal direction of the developing roller 17 and the photosensitive drum 1. Further, a left developing side plate 19L, a hole 19La, and a left connecting shaft 23L are disposed on the other end side in the longitudinal direction of the developing roller 17 and the photosensitive drum 1.

  Inside the developing frame 18, a toner storage chamber 18a which is a “developer storage chamber” is formed. In the toner storage chamber 18a, non-magnetic one-component toner as “non-magnetic one-component developer” which is “developer” is stored. The toner storage chamber 18 a is provided with a toner transport member 22 that is a “developer transport member” that is rotatably supported at both ends in the longitudinal direction (rotation axis direction) of the developing frame 18. The toner conveying member 22 is rotationally driven in the direction of arrow G (clockwise) by a driving unit (driving source) (not shown). The toner conveying member 22 has a function of agitating the toner accommodated in the toner accommodating chamber 18a and conveying the toner to the developing chamber 18b provided with the developing roller 17 and the supply roller 20. The present invention can also be applied to a developer container (toner cartridge) that includes only the toner storage chamber 18a and the toner conveying member 22 and is detachable from the apparatus main body 100a.

  The toner conveyance member 22 includes a conveyance support shaft 22b that is a “rotating shaft” and a sheet portion 22a that is a “conveyance unit”. The conveyance support shaft 22b, which is a “rotation shaft”, is disposed over the entire region in the longitudinal direction of the toner storage chamber 18a substantially parallel to the longitudinal direction (rotation axis direction) of the photosensitive drum 1, the developing roller 17, and the supply roller 20. And a shaft that receives a rotational driving force from the driving means. The sheet portion 22a, which is a “conveying portion”, has a base end portion that is attached to substantially the entire longitudinal direction (rotational axis direction) of the conveying support shaft 22b and continuously spreads in the longitudinal direction to convey the toner ( Plate-like member). Further, the base portion of the sheet portion 22a is attached to the conveyance support shaft 22b so that the plate surface is along a direction (rotational radius direction) substantially orthogonal to the longitudinal direction of the conveyance support shaft 22b. Furthermore, the sheet | seat part 22a can be suitably produced using flexible resin-made sheets, such as a polyester film, a polyphenylene sulfide film, a polycarbonate film, for example. The thickness of the sheet portion 22a is preferably 50 μm to 250 μm.

  The developing frame 18 includes a toner storage chamber 18a that is a “developer storage chamber” that stores the developer, and a development chamber 18b adjacent to the toner storage chamber 18a. The toner storage chamber 18 a and the developing chamber 18 b are partitioned by a partition wall 26 that extends in a direction parallel to the axes of the developing roller 17 and the supply roller 20. An opening 27 is formed in the partition wall 26.

  The inner wall of the toner storage chamber 18a has, in order from the lowermost surface side, a toner gathering portion 18a1, a conveying portion 18a3, and a restoring portion 18a4. A boundary point between the toner gathering part 18a1 and the conveying part 18a3 is defined as a boundary part p. A boundary point between the transport unit 18a3 and the restoration unit 18a4 is a branching unit r. Therefore, the toner storage chamber 18a includes the toner approaching portion 18a1, the boundary portion p, the transporting portion 18a3, the branching portion r, and the restoring portion 18a4 in this order from the upstream side in the rotation direction of the toner transporting member 22. The boundary portion p of the inner wall surface of the toner storage chamber 18a is downstream in the rotational direction of the toner conveying member 22 with respect to the lowest portion q, and the angle with respect to the horizontal plane is less than the repose angle of the developer to the repose angle or more. It corresponds to the point that changes. Further, the downstream side in the rotation direction of the toner conveying member 22 with respect to the boundary portion p corresponds to the conveying portion 18a3 that is an area having a repose angle of the toner or more. Further, the upstream side in the rotation direction of the toner conveying member 22 with respect to the boundary portion p corresponds to the toner approaching portion 18a1 that is a region less than the repose angle of the toner. Here, the toner gathering portion 18 a 1 is disposed in a region below the rotation center K of the toner conveying member 22.

  The following settings are made with reference to such a boundary portion p. In other words, the amount of deformation that the sheet portion 22a of the toner conveying member 22 deforms while contacting the inner wall surface of the toner storage chamber 18a is longer in the longitudinal direction than the boundary portion p in the longitudinal direction in the longitudinal direction. The longitudinal end portions 22y are set larger than the portion 22x. In this regard, refer to FIG. Further, on the downstream side in the rotation direction of the toner conveying member 22 with respect to the boundary portion p, the longitudinal center portion 22x and the longitudinal both end portions 22y are set substantially uniformly in the longitudinal direction.

  Further, a convex portion 18a5 is formed on the inner wall of the toner gathering portion 18a1. The convex portion 18a5 is formed to have a lower slope as it advances in the rotation direction of the toner conveying member 22. The convex portions 18a5 are formed only at both ends in the axial direction of the transport support shaft 22b (described later).

  As described above, the toner conveying member 22 is disposed inside the toner storage chamber 18a. The toner conveying member 22 is configured to convey toner from the toner containing chamber 18a to the developing chamber 18b via the opening 27 while rotating. When the toner conveying member 22 rotates inside the toner storage chamber 18a, the sheet portion 22a contacts the convex portion 18a5 of the toner gathering portion 18a1, and the longitudinal end portions 22y are deformed in the longitudinal direction rather than the longitudinal central portion 22x. It moves while deforming so as to increase the amount (see FIG. 3B). Then, when the sheet part 22a exceeds the boundary part p, the sheet part 22a is released from the deformed state at the toner gathering part 18a1, and the sheet part 22a comes into contact with the conveying part 18a3 so that the longitudinal central part 22x and the longitudinal both end parts 22y are substantially uniform in the longitudinal direction. It moves while being deformed (see FIG. 4B). The reason why the inclination angle of the inner wall of the toner storage chamber 18a is set to be substantially the same as the angle of repose angle of the toner at the point of the boundary portion p is as follows. That is, the toner is prevented from dropping from above the sheet portion 22a after the time when the sheet portion 22a exceeds the boundary portion p. Thus, the toner is conveyed to the opening 27 without leakage.

  A developing roller 17 and a supply roller 20 are disposed inside the developing chamber 18b. The toner that has passed through the opening 27 is carried on the rotating supply roller 20, and then carried on the rotating developing roller 17 and developed onto the photosensitive drum 1.

  Fig.3 (a) is sectional drawing which follows the XX line | wire of FIG. 2 which shows the structure of the conveyance support shaft 22b and the convex part 18a5. As shown in FIG. 3A, convex portions 18a5 are formed in the toner gathering portion 18a1 corresponding to both end sides in the axial direction of the transport support shaft 22b. For this reason, the following is set on the upstream side in the rotation direction of the toner conveying member 22 with respect to the boundary portion p on the inner wall surface of the toner storage chamber 18a. That is, the distance between the inner wall surface of the toner storage chamber 18a and the rotation center K of the toner conveying member 22 is set to be greater in the longitudinal central portion J than in the longitudinal both ends W in the longitudinal direction of the toner conveying member 22. It becomes. That is, as shown in FIG. 3A, the distance L2T from the conveyance support shaft 22b to the longitudinal center portion J is set larger than the distance L2R from the conveyance support shaft 22b to both longitudinal ends W. is there.

  Here, it is assumed that the sheet portion 22a moves from the back side to the front side in FIG. In this case, the moving speed of the longitudinal center portion J and the longitudinal end portions W of the sheet portion 22a of the toner conveying member 22 is examined. The longitudinal both ends W have a first end W1 that is one end and a second end W2 that is the other end. If it does so, the longitudinal both ends W will be prevented from advancing by the convex part 18a5, a shape will deform | transform, and a conveyance speed will become slow. In addition, in the axial direction of the conveyance support shaft 22b, the convex portion width m as the length of the convex portion 18a5 shown in FIG. 3A is set to 30 mm to 50 mm. However, if the convex portions 18a5 are formed at the longitudinal end portions W parallel to the longitudinal direction of the conveyance support shaft 22b on the inner wall surface of the toner gathering portion 18a1, the convex portion width m is limited to the above-described dimensions of 30 mm to 50 mm. However, it may be longer than this or shorter than this. Further, the shape of the convex portion 18a5 may be other shapes.

  FIG. 3B is a perspective view of the toner conveying member 22 showing a shape changing process of the sheet portion 22a when the toner conveying member 22 rotates. As shown in FIG. 3 (b), the longitudinal end portions 22y of the sheet portion 22a are hindered by the convex portion 18a5 and bent backward to be deformed, so that the sheet portion 22a is deformed by the longitudinal central portion 22x. The moving speed is faster, and the moving speed is slower at the longitudinal end portions 22y. Along with this, the toner in the longitudinal center portion 22x of the sheet portion 22a is drawn toward the longitudinal end portions 22y of the sheet portion 22a.

  4A is a cross-sectional view showing the configuration of the right opening 27R and the left opening 27L as viewed from the direction α in FIG. As shown in FIG. 4A, the right opening that is the “first opening” in the direction parallel to the rotation axis that is the “axis” of the supply roller 20 and the rotation axis that is the “axis” of the developing roller 17. The portion 27R and the left opening 27L, which is the “second opening”, are arranged side by side at a predetermined interval. The right opening 27R is formed so as to penetrate through one end in the longitudinal direction in which the partition wall 26 (see FIG. 2) extends, and the left opening 27L is the other end in the longitudinal direction in which the partition wall 26 (see FIG. 2) extends. It is formed penetrating to the part side. These right side opening 27R and left side opening 27L are formed in the partition wall 26 shown in FIG. 2, and are formed above the toner storage chamber 18a. It is desirable that the opening widths u provided at both ends of the opening 27 in the longitudinal direction of the toner storage chamber 18a are each set to 10 mm or more. If the opening width u is set to less than 10 mm, a desired solid density may not be obtained. Further, it is desirable that the opening width u is set to be approximately 60% or less of the entire length of the entire length in the both ends. When the opening width u exceeds 60% of the length of the entire longitudinal area, the toner conveyed to the developing chamber 18b falls again into the toner storage chamber 18a, and the toner is difficult to be held in the developing chamber 18b. As a result, there is a possibility that an image following failure may occur. Furthermore, the opening height t is preferably set to 4 mm or more. If the opening height t is less than 4 mm, a desired concentration may not be obtained. In the embodiment, the opening width u is set to 25 mm and the opening height t is set to 8 mm.

  As described above with reference to FIG. 2, on the inner wall surface of the developing device frame 18, the restoring portion 18 a 4 exists on the downstream side in the rotation direction of the toner conveying member 22 with respect to the conveying portion 18 a 3. The boundary between the transport unit 18a3 and the restoration unit 18a4 is called a branching unit r. Therefore, the transport unit 18a3 indicates a region from the boundary portion p to the branch portion r of the toner storage chamber 18a. The branch portion r corresponds to a boundary point where the free end of the sheet portion 22a branches from the contact state to the non-contact state with the inner wall of the toner storage chamber 18a. The deformation amount of the sheet portion 22a in contact with the conveying portion 18a3 is restored while contacting the restoring portion 18a4 after exceeding the branch portion r, and the deformation amount of the sheet portion 22a becomes substantially uniform in the longitudinal direction. Therefore, the toner attracted to the longitudinal end portions 22y in the longitudinal direction of the sheet portion 22a by the toner gathering portion 18a1 does not fall to the lower end of the toner housing chamber 18a even in the restoring portion 18a4, and from the toner housing chamber 18a against gravity. It is conveyed to the developing chamber 18b.

  Next, the dimensional relationship between the toner storage chamber 18a and the toner transport member 22 will be described, and the process of transporting toner as the toner transport member 22 rotates will be described. Here, the distance from the rotation center K of the toner conveying member 22 to each portion is defined as follows (see FIG. 2). “L1” is the distance from the rotation center K of the toner conveying member 22 to the free end of the sheet portion 22a (L1 is the maximum radius of rotation of the toner conveying member 22 in a natural state where the sheet portion 22a is not deformed). It corresponds to the distance.) “L2” is a distance at which the linear distance from the rotation center K of the toner conveying member 22 to the toner approaching portion 18a1 on the inner wall of the toner storage chamber 18a that contacts the sheet portion 22a is the maximum value. “L2R” is a distance from the rotation center K of the toner conveying member 22 to both longitudinal ends W (FIG. 3A) of the toner gathering portion 18a1 of the inner wall of the toner storage chamber 18a that contacts the sheet portion 22a. “L2T” is the distance from the rotation center K of the toner conveying member 22 to the longitudinal central portion J (FIG. 3A) of the toner gathering portion 18a1 of the inner wall of the toner storage chamber 18a that contacts the sheet portion 22a. “L3” is a linear distance from the rotation center K of the toner conveying member 22 to the lowest point of the opening 27. “L4” is a distance at which the linear distance from the rotation center K of the toner conveying member 22 to the conveying portion 18a3 becomes the maximum value.

  The distances L1, L2, L2R, L2T, L3, and L4 defined in this way are L1> L2 (1), L2T> L2R (2), L1> L4 (3), The relationship of four formulas L1> L3 (4) is satisfied. Here, since L1> L2 (1), the sheet portion 22a is deformed in contact with the toner gathering portion 18a1 on the inner wall of the toner storage chamber 18a. Further, since L2T> L2R (2), the longitudinal end portions 22y of the sheet portion 22a are bent more greatly to the toner gathering portion 18a1 on the inner wall of the toner containing chamber 18a than the longitudinal central portion 22x of the sheet portion 22a. Abut. Therefore, the toner in the longitudinal center portion 22x of the sheet portion 22a can be brought close to the longitudinal end portions 22y by advancing the rotation while the toner conveying member 22 is deformed by the elasticity of the sheet portion 22a. Similarly, in the conveyance unit 18a3, the sheet portion 22a abuts on the conveyance unit 18a3 on the inner wall of the toner storage chamber 18a, and rotates while being deformed by the elasticity of the sheet unit 22a.

  FIG. 4B is a perspective view of the toner conveying member 22 showing a change in the shape of the sheet portion 22a in the conveying portion 18a3. Since L1> L4 (4), the sheet portion 22a deforms in contact with the conveying portion 18a3 on the inner wall of the toner storage chamber 18a. In this case, as shown in FIG. 4B, since the deformation amount of the sheet portion 22a is substantially uniform in the longitudinal direction, the sheet portion 22a is on the surface of the sheet portion 22a brought close to the longitudinal end portions 22y. The toner can be conveyed against the direction of gravity.

  When the toner conveying member 22 further rotates from the conveying portion 18a3, the free end of the sheet portion 22a passes through the branch portion r and reaches the restoring portion 18a4. In the restoring portion 18a4, the free end of the sheet portion 22a does not come into contact with the inner wall of the toner storage chamber 18a. Therefore, the restoring portion 18a4 is released from the deformed state by the conveying portion 18a3, and is in a natural state by its own elastic restoring force ( To the original shape). Thus, the restoration of the sheet part 22 a allows the toner carried and conveyed on the toner conveying member 22 to fly toward the opening 27. Here, since the opening 27 is provided above the branch part r, the toner flies against the direction of gravity.

[First Comparative Example]
FIG. 5A is a cross-sectional view showing the configuration of the process cartridge 107 according to the first comparative example. In the description of the process cartridge 107 of the first comparative example with reference to FIG. 5A, the members having the same configuration and effect as those of the process cartridge 7 of the embodiment are denoted by the same reference numerals and the description is incorporated. . As shown in FIG. 5A, the process cartridge 107 of the first comparative example is different from the process cartridge 7 of the embodiment in the following points. In the process cartridge 107 of the first comparative example, the convex portion 18a5 characterized in the embodiment is not formed on the floor side inner wall portion 18h1 of the toner storage chamber 118a of the developing device frame 118. Regarding other configurations, the configuration of the process cartridge 107 of the first comparative example is the same as the configuration of the process cartridge 7 described in the embodiment. With such a configuration, in the process cartridge 107 of the first comparative example, the longitudinal end portions 22y of the sheet portion 22a of the toner conveying member 22 are in contact with the floor side inner wall portion 18h1 rather than the longitudinal central portion 22x and are greatly deformed. The phenomenon does not occur.

  The following dimensions are set in the toner storage chamber 18a. The distance L1 from the rotation center K of the toner conveying member 22 to the free end of the sheet portion 22a is a straight line from the rotation center K of the toner conveying member 22 to the floor side inner wall portion 18h1 of the toner storage chamber 18a that contacts the sheet portion 22a. The distance L2 is set to be larger than the maximum distance. Here, the distance L1 is a distance at which the rotation radius of the toner conveying member 22 in a natural state where the sheet portion 22a is not deformed becomes a maximum value.

  The distance L1 is set larger than the linear distance L3 from the rotation center K of the toner conveying member 22 to the lowest point of the opening 27 as in the embodiment. The distance L4 at which the linear distance from the rotation center K of the toner conveyance member 22 to the conveyance unit 18a3 is the maximum value is set smaller than the distance L1 from the rotation center K of the toner conveyance member 22 to the free end of the sheet unit 22a. Yes. The conveyance portion 18a3 is a portion that contacts the toner conveyance member 22 below the opening 27 and uniformly deforms the sheet portion 22a in the longitudinal direction.

  Thus, in the first comparative example, L1, L2, L3, and L4 are three expressions such as L1> L2 (1), L1> L3 (3), L1> L4 (4). Satisfy the relationship. Here, by satisfying the relationship of L1> L2 (1), the sheet portion 22a abuts against the floor side inner wall portion 18h1 of the toner storage chamber 18a and is rotated along with the rotation, as in the embodiment. Bend greatly. Further, by satisfying the relationship of L1> L3 (3), as in the embodiment, the free end of the sheet portion 22a that is in a natural state after the deformation of the sheet portion 22a is released is When the portion 22 a reaches the opening 27, it is located above the lower end of the opening 27. Therefore, the toner can be conveyed to the developing chamber 18b. Further, by satisfying the relationship of L1> L4 (4), the sheet portion 22a is bent in contact with the conveying portion 18a3, and the toner accumulated on the sheet portion 22a is conveyed to the developing chamber 18b.

  FIG. 5B is a perspective view of the toner conveying member 22 showing a change in shape when the toner conveying member 22 contacts the inner wall of the toner storage chamber 118a. In the first comparative example, the opening portions 27 connected from the toner storage chamber 118a to the developing chamber 18b are formed on both ends of the long side as in the embodiment (see FIG. 4A). However, in the first comparative example, since the toner conveying member 22 does not go through a process of contacting and protruding on the convex portion and deforming, there is no mechanism for bringing the toner on the sheet portion 22a of the toner conveying member 22 to both ends. . Therefore, as shown in FIG. 5B, the toner conveying member 22 does not cause the toner to approach the longitudinal end portions 22y. Further, since the opening 27 is divided into the right opening 27R and the left opening 27L, the toner on the longitudinal center portion 22x of the sheet portion 22a cannot pass through the opening 27.

[Second Comparative Example]
FIG. 6A is a cross-sectional view showing the configuration of the process cartridge 207 according to the second comparative example. In the description of the process cartridge 207 of the second comparative example with reference to FIG. 5B, the members having the same configuration and effect as those of the process cartridge 7 of the embodiment are denoted by the same reference numerals and the description is incorporated. . As shown in FIG. 6A, the process cartridge 207 of the second comparative example is different from the process cartridge 7 of the embodiment in the following points. In the process cartridge 207 of the second comparative example, the sheet portion 22a is on the inner wall surface of the toner storage chamber 18a from the boundary portion p of the developing device frame 218 to the conveyance portion 18a3 downstream in the rotation direction of the toner conveyance member 22. The amount of deformation that abuts and deforms is uneven in the longitudinal direction. That is, the convex part 18a5 is formed continuously to the branch part r. Regarding other configurations, the configuration of the process cartridge 207 of the second comparative example is the same as the configuration of the process cartridge 7 described in the embodiment. With such a configuration, in the process cartridge 207 of the second comparative example, the toner attracted to the longitudinal end portions 22y of the toner conveying member 22 is likely to fall while being largely deformed when passing through the conveying portion 18a3.

  Inside the toner storage chamber 18a, convex portions 18a5 are provided at both longitudinal ends W extending from the toner gathering portion 18a1 to the transport portion 18a3. In the relationship between the longitudinal center portion 22x of the sheet portion 22a of the toner transport member 22 and the longitudinal end portions 22y, the transport speed is set to be slower at the longitudinal end portions 22y. L1, L2R, L2T, L3, and L4 are the same as those shown in the embodiment, but the L2R and L2T here are as follows.

  L2R is a distance at which the linear distance from the rotation center K of the toner conveying member 22 to the longitudinal end portions W of the inner wall (18a1 and 18a3) of the toner storage chamber 18a that contacts the sheet portion 22a is the minimum value. L2T is a distance at which the linear distance from the rotation center K of the toner conveying member 22 to the longitudinal central portion J of the inner wall (18a1 and 18a3) of the toner storage chamber 18a in contact with the sheet portion 22a is the maximum value. As a result, the longitudinal end portions 22y of the sheet portion 22a are bent and contacted with the toner gathering portion 18a1 and the conveying portion 18a3 so as to be larger than the longitudinal central portion 22x, and the sheet portion 22a protrudes to the longitudinal central portion J of the toner storage chamber 18a. Move in a bulging state. Therefore, rotation is advanced in the state deform | transformed with the elasticity which the sheet | seat part 22a has. As a result, the toner in the longitudinal center portion 22x of the sheet portion 22a is brought to the longitudinal end portions 22y of the sheet portion 22a. In other words, the toner gathering portion 18a1 that is set so that the deformation amount of the longitudinal end portions 22y of the sheet portion 22a is larger than that of the longitudinal central portion 22x is provided in the region up to the branching portion r.

  FIG. 6B is a perspective view of the toner transport member 22 showing a shape change when the toner transport member 22 contacts the inner wall of the toner storage chamber 218a. In the second comparative example, the openings 27 that connect from the toner storage chamber 218a to the developing chamber 18b are formed on both longitudinal ends as in the embodiment (see FIG. 4A), and correspond to the two openings 27. There is also a mechanism for bringing the toner in the longitudinal center portion 22x toward the longitudinal end portions 22y. However, the mechanism is not capable of holding the toner on the sheet portion 22a when the sheet portion 22a of the toner conveying member 22 is released. Accordingly, the sheet portion 22a of the toner conveying member 22 is deformed by the convex portion 18a5 formed from the toner gathering portion 18a1 to the branching portion r, and the longitudinal end portions 22y of the sheet portion 22a have a drooping shape. As a result, after the branching portion r, the toner that has approached the longitudinal end portions 22y of the sheet portion 22a at the toner gathering portion 18a1 spills from both ends at the transport portion 18a3.

  Next, the evaluation method of an Example and a 1st comparative example and a 2nd comparative example is described. First, (1) an initial density follow-up evaluation is performed. In the density follow-up evaluation, the image forming apparatus is left in an evaluation environment at 25.0 ° C. and 50% Rh for one day to adjust to the environment. Thereafter, three solid black images were output in succession, and evaluation was performed using a spectrum densitometer 500 manufactured by X-Rite from the density difference between the output front and rear ends of the third solid black image. The print test and evaluation image are output in a single color. In this evaluation, before outputting a solid black image, 10 horizontal line recorded images with an image ratio of 5% are compared after printing. Further, the amount of toner filled in the toner storage chamber 18a is 200 g. ○ is a density difference between the leading edge and the trailing edge of the paper in a solid black image is less than 0.2, and Δ is a density difference between the leading edge and the trailing edge of the paper in a solid black image is 0.2 to 0.4. Less than x indicates that the density difference between the leading edge and the trailing edge of the paper is 0.4 or more in a solid black image.

  Next, density followability evaluation after durability is performed. In the density follow-up evaluation, the image forming apparatus is left in an evaluation environment at 25.0 ° C. and 50% Rh for one day to adjust to the environment. Thereafter, three solid black images were output in succession, and evaluation was performed using a spectrum densitometer 500 manufactured by X-Rite from the density difference between the output front and rear ends of the third solid black image. The print test and evaluation image are output in a single color. In this evaluation, before outputting a solid black image, a horizontal line recorded image with an image ratio of 5% is compared after printing 20,000 sheets. ○ is a density difference between the leading edge and the trailing edge of the paper in a solid black image is less than 0.2, and Δ is a density difference between the leading edge and the trailing edge of the paper in a solid black image is 0.2 to 0.4. Less than x indicates that the density difference between the leading edge and the trailing edge of the paper is 0.4 or more in a solid black image.

  The evaluation results of this example and the first and second comparative examples will be described. Table 1 is a comparison table of evaluation results applied to the examples and the first and second comparative examples.

こうした評価結果に基づいて、従来技術に対する実施例の優位性に関して述べる。すなわち、トナー搬送構成についての特許文献１に対する実施例の優位性に関して述べる。特許文献１の現像ユニット６０では、図６（ｃ）のように、現像剤を現像剤収容室６１からその上方の現像室６２へと搬送するために、現像剤収容室６１の内部に現像剤を搬送するトナー搬送部材６３が設けられる。そして、トナー搬送部材６３は、現像剤を撹拌する撹拌部材６３ａの先端に、可撓性のシート部材６３ｂが取り付けられて構成されている。また、特許文献１の現像ユニットでは、現像剤収容室６１から現像室６２へと現像剤を通過させる開口部６４は、長手方向の全域に形成されている。さらに、現像ブレード６５の下方にも、現像剤収容室６１へと現像剤を通過させる開口部６７が設けられ、現像室６２では現像剤が保持され難い構成となっている。その結果、トナーが供給ローラ６６に搬送されずに、べた画像が出力された場合には、画像の先端では所望の濃度が得られたとしても、画像の中央から後端に亘って濃度薄が発生してしまう（所謂、画像濃度追従不良）。また、前述したように、現像剤収容室６１からその上方の現像室６２へと現像剤を搬送する場合に、開口部６４が長手方向の全域にある。こうした構成では、画像濃度の追従性が不良になり、所望の濃度を得ることは困難であった。また、現像剤収容室６１からその上方の現像室６２へと現像剤を搬送するために、現像剤収容室６１の現像剤を撹拌する撹拌部材６３ａの先端に、可撓性のシート部材６３ｂが取付けられる構成となっている。こうした構成では、撹拌部材６３ａの先端部にシート部材６３ｂが取付けられるために、トナー搬送部材６３の小型化が困難となる。

Based on these evaluation results, the superiority of the embodiment over the prior art will be described. That is, the superiority of the embodiment with respect to Patent Document 1 regarding the toner conveyance configuration will be described. In the developing unit 60 of Patent Document 1, as shown in FIG. 6C, in order to convey the developer from the developer accommodating chamber 61 to the developing chamber 62 above the developer accommodating chamber 61, the developer is placed inside the developer accommodating chamber 61. A toner conveying member 63 for conveying the toner is provided. The toner conveying member 63 is configured by attaching a flexible sheet member 63b to the tip of an agitating member 63a for agitating the developer. Further, in the developing unit of Patent Document 1, the opening 64 through which the developer passes from the developer accommodating chamber 61 to the developing chamber 62 is formed in the entire area in the longitudinal direction. Further, an opening 67 for allowing the developer to pass into the developer accommodating chamber 61 is also provided below the developing blade 65, so that the developer is hardly held in the developing chamber 62. As a result, if the toner is not conveyed to the supply roller 66 and a solid image is output, even if a desired density is obtained at the leading edge of the image, the density decreases from the center to the trailing edge of the image. (So-called poor image density tracking). Further, as described above, when the developer is transported from the developer accommodating chamber 61 to the developing chamber 62 thereabove, the opening 64 is in the entire region in the longitudinal direction. With such a configuration, the followability of the image density becomes poor, and it is difficult to obtain a desired density. In addition, in order to transport the developer from the developer storage chamber 61 to the development chamber 62 thereabove, a flexible sheet member 63b is provided at the tip of the stirring member 63a that stirs the developer in the developer storage chamber 61. It is configured to be attached. In such a configuration, since the sheet member 63b is attached to the tip of the stirring member 63a, it is difficult to reduce the size of the toner conveying member 63.

  On the other hand, in the developing unit 4 of the embodiment, toner is transferred from the toner storage chamber 18a to the developing chamber 18b from the right opening 27R and the left opening 27L at both ends in the longitudinal direction of the partition wall 26 that hardly affects the image. It is conveyed. Therefore, it is difficult for the toner to return from the developing chamber 18b to the toner storage chamber 18a, and high-quality image formation with little change in image density over time can be performed. Further, the toner inside the toner storage chamber 18a is moved from the longitudinal central portion 22x in the longitudinal direction of the sheet portion 22a to the longitudinal both end portions 22y, and the toner is prevented from dropping in the direction of gravity while being efficiently transferred to the opening portion 27. Convey well. Therefore, the developer remaining without being pumped up at the longitudinal center J of the toner storage chamber 18a can be used. For this reason, even when the amount of toner decreases in the second half of the endurance, image follow-up failure in which the density decreases from the center of the image to the rear end of the image is prevented, and the amount of remaining toner is reduced. Further, the toner transport member 22 has a simple configuration including a transport support shaft 22b and a sheet portion 22a whose base end is fixed to the transport support shaft 22b. Therefore, simplification and downsizing of the configuration of the toner conveying member 22 are realized. In addition, the sheet portion 22a has elasticity, and can rotate while being deformed with respect to the inner wall of the toner storage chamber 18a. Therefore, the toner storage chamber 18a can be downsized.

  Next, the superiority of the embodiment over the first comparative example and the second comparative example will be described based on the above-described evaluation results. In the developing unit 4 of the embodiment, the opening 27 through which the toner is supplied from the toner storage chamber 18a to the developing chamber 18b is formed on both ends of the longitudinal side which hardly affects the image, thereby reducing the image density difference. A few good images can be obtained stably. Further, a boundary portion p is assumed in which the inclination angle on the downstream side in the rotation direction of the toner conveying member 22 from the lowermost q of the toner storage chamber 18a is equal to or greater than the repose angle of the toner. Then, in the region upstream of the boundary portion p in the rotation direction of the toner conveyance member 22 and below the rotation center K of the toner conveyance member 22 (toner approaching portion 18a1), the following occurs. That is, the amount of deformation of the toner conveying member 22 in contact with the inner wall surface of the toner storage chamber 18a is larger at the longitudinal end portions 22y than at the longitudinal central portion 22x. Further, in the region downstream of the boundary portion p in the rotation direction of the toner conveying member 22 (conveying portion 18a3), the amount of deformation that the toner conveying member 22 abuts against the inner wall surface of the toner containing chamber 18a is substantially in the longitudinal direction. It is set uniformly. As a result, the toner in the longitudinal central portion J of the toner storage chamber 18a is brought close to the longitudinal end portions W by the toner conveying member 22. Further, since the bending of the sheet portion 22a is equalized before the sheet portion 22a of the toner conveying member 22 is opened, the toner is prevented from spilling in the direction of gravity, and the efficiency is improved from the openings 27 at both ends to the developing chamber 18b. In particular, toner is supplied. As a result, in the developing unit 4 of the embodiment, when the toner in the toner storage chamber 18a decreases from the initial stage to the end of the durability period, the toner is efficiently conveyed to the developing chamber 18b, and the solid density follow-up property is achieved. Is secured.

  In the developing unit 104 of the first comparative example, the opening 27 through which the toner is passed from the toner storage chamber 118a to the developing chamber 18b is formed on both ends of the longitudinal side which hardly affects the image. The configuration is the same as that of the developing unit 4. Here, a boundary portion p is assumed in which the inclination angle on the downstream side in the rotation direction of the toner conveying member 22 from the lowermost part q of the toner storage chamber 118a is equal to or greater than the repose angle of the toner. As a result, the region upstream of the rotation direction K of the toner conveying member 22 and the region below the rotation center K of the toner conveying member 22 (floor surface side inner wall portion 18h1) is different from the case of the embodiment. That is, the amount of deformation of the toner conveying member 22 in contact with the inner wall surface of the toner storage chamber 118a is not configured such that the longitudinal end portions W are larger than the longitudinal central portion J. For this purpose, the opening 27 is formed on both ends of the longitudinal side so that the toner is easily held in the developing chamber 18b. However, the configuration is not such that the toner in the toner storage chamber 118a is moved toward the longitudinal end portions 22y by the deformation of the sheet portion 22a and the toner is conveyed to the opening 27 while preventing the toner from falling in the direction of gravity. Therefore, the amount of toner supplied from the toner storage chamber 118a to the developing chamber 18b becomes insufficient. As a result, compared with the example, since there is sufficient toner in the toner storage chamber 18a in the early stage of durability, a good image without image tracking failure can be obtained as in the example. However, when the remaining amount of toner in the second half of the endurance decreases, the amount of toner supplied to the developing chamber 18b becomes insufficient, resulting in an image follow-up defect in which the density decreases from the center to the rear end of the image. End up.

  In the developing unit 204 of the second comparative example, as in the embodiment, the opening portions 27 through which the toner is supplied from the toner storage chamber 218a to the developing chamber 18b are formed at both longitudinal end portions that hardly affect the image. . Here, a boundary portion p is assumed in which the inclination angle of the inner wall surface of the toner storage chamber 218a, which is downstream in the rotation direction of the toner conveying member 22 from the lowermost part q of the toner storage chamber 218a, is equal to or greater than the repose angle of the toner. Then, in the region upstream of the boundary portion p in the rotation direction of the toner conveyance member 22 and below the rotation center K of the toner conveyance member 22 (toner approaching portion 18a1), the following occurs. That is, the amount of deformation at which the sheet portion 22a abuts against the inner wall surface of the toner storage chamber 218a is set to be larger at the longitudinal end portions W than at the longitudinal central portion J. However, in the region downstream of the boundary portion p in the rotation direction of the toner conveying member 22 (conveying portion 18a3), the amount of deformation that the toner conveying member 22 abuts against the inner wall surface of the toner containing chamber 18a is approximately the longitudinal direction. It is not a uniform structure. Therefore, even if the toner conveying member 22 moves the toner toward both ends and lifts it to the boundary portion p in accordance with the opening portions 27 on both ends of the longitudinal side, the toner is not removed when the sheet portion 22a of the toner conveying member 22 is opened. It will be in the state where it was brought close to the longitudinal both ends 22y. For this reason, since the longitudinal end portions 22y of the sheet portion 22a hang down in the direction of gravity, the toner attracted to the longitudinal end portions 22y falls to the bottom of the toner storage chamber 218a. As a result, compared with the embodiment, the amount of toner supplied from the toner storage chamber 218a to the developing chamber 18b decreases, and the sheet portion 22a of the toner conveying member 22 is opened from both longitudinal end portions 22y of the sheet portion 22a. Toner spills in the direction of gravity. For this reason, a slight image follow-up failure occurs in which the density decreases from the center of the image to the rear end in the initial stage of durability. Further, when the remaining amount of toner decreases in the second half of the endurance, the toner conveyance to the developing chamber 18b becomes extremely insufficient, and the supply of toner is remarkably reduced, resulting in a low density from the center of the image to the rear end of the image. Significant image following failure occurs.

  As described above, according to the developing unit 4 of the embodiment, the amount of deformation that the toner conveying member 22 deforms while contacting the inner wall surface is longer on the upstream side in the rotation direction of the toner conveying member 22 than the boundary portion p. The longitudinal end portions 22y are set larger in the direction than the longitudinal central portion 22x. Accordingly, the toner inside the toner storage chamber 18a is drawn from the longitudinal central portion 22x side to the longitudinal both end portions 22y side in the longitudinal direction of the toner conveying member 22. The amount of deformation that the toner conveying member 22 deforms while coming into contact with the inner wall surface is set to be substantially uniform in the longitudinal direction downstream of the boundary portion p in the rotational direction of the toner conveying member 22. Therefore, the toner is prevented from dropping in the direction of gravity, and the toner is efficiently conveyed to the opening 27. As a result, at the position of the inner wall surface of the toner storage chamber 18a corresponding to the longitudinal central portion 22x in the longitudinal direction of the toner conveying member 22, the toner remaining without being pumped is reduced. For this reason, when the amount of toner in the toner storage chamber 18a is reduced, image follow-up failure that is thin in density from the center to the rear end of the image is suppressed, and high-quality image formation is performed. The developer inside the storage chamber 18a is used without waste.

  The toner conveyance member 22 has a simple configuration including a conveyance support shaft 22b and a sheet portion 22a that is supported by the conveyance support shaft 22b and has elasticity. The transport member of the prior art was configured to include a transport support shaft, a stirring member supported by the transport support shaft, and a sheet portion having elasticity at the tip of the stirring member. A sheet portion 22a having elasticity is directly attached to the conveyance support shaft 22b. Therefore, in the developing unit 4 of the embodiment, the configuration of the toner conveying member 22 can be simplified and downsized. Further, the toner conveying member 22 has elasticity, and can rotate while being deformed with respect to the inner wall surface of the toner storage chamber 18a. Accordingly, the toner storage chamber 18a can be downsized.

  According to the developing unit 4 of the embodiment, the openings 27 are the right-side opening 27R and the left-side opening 27L formed on both ends in the longitudinal direction of the partition wall 26. Therefore, when the opening 27 is formed on both ends in the longitudinal direction of the partition wall 26 as compared with the case where the opening 27 is formed in the entire region in the longitudinal direction of the partition wall 26, the developer is reduced. Returning from the developing chamber 18b to the toner storage chamber is suppressed. As a result, it is possible to form a high quality image with little change in image density over time.

  According to the developing unit 4 of the embodiment, the distance between the inner wall surface of the toner storage chamber 18a and the rotation center K of the toner conveying member 22 is longer than both longitudinal end portions 22y of the sheet 22a of the toner conveying member 22 in the longitudinal direction. The longitudinal center portion 22x is set larger. Therefore, when the toner conveying member 22 rotates, the longitudinal end portions 22y in the longitudinal direction of the sheet portion 22a rotate while being constrained by the inner wall surfaces (longitudinal end portions W) of the toner storage chamber 18a. At the same time, a phenomenon occurs in which the longitudinal central portion 22x in the longitudinal direction of the sheet portion 22a rotates without being constrained by the inner wall surface (longitudinal central portion J) of the toner storage chamber 18a. As a result, the developer is brought close to both longitudinal end portions 22 y in the longitudinal direction of the sheet portion 22 a of the toner conveying member 22.

4 Development unit (developing device)
17 Development roller (developer carrier)
18a Toner storage chamber (developer storage chamber)
18b Development chamber 22 Toner transport member (developer transport member)
22x Longitudinal center portion 22y Longitudinal both ends 26 Partition wall 27 Opening portion 27R Right opening portion (opening portion)
27L Left side opening (opening)
p boundary

Claims (5)

A developer storage chamber for storing the developer;
A developing chamber adjacent to the developer containing chamber;
A partition wall that partitions the developer storage chamber and the development chamber;
An opening penetrating the partition wall;
A developer conveying member that is disposed inside the developer accommodating chamber and conveys the developer from the developer accommodating chamber to the developing chamber via the opening while rotating;
In a developing device that is disposed inside the developing chamber and includes a developer carrying member that carries the developer while rotating,
On the inner wall surface of the developer storage chamber, the angle with respect to the horizontal plane changes from less than the repose angle of the developer to more than the repose angle on the downstream side in the rotation direction of the developer transport member from the lowest point of the lowest height. When the boundary point to be used is the boundary,
The deformation amount of the developer conveying member deformed while abutting against the inner wall surface is larger at the upstream side in the rotation direction of the developer conveying member than at the boundary portion at both ends in the longitudinal direction than at the central portion in the longitudinal direction. The developing device is set to be larger, and is set to be substantially uniform in the longitudinal direction downstream of the boundary portion in the rotation direction of the developer conveying member. The partition wall extends in a direction parallel to the axis of the developer carrier;
The opening includes a first opening formed on one end in the longitudinal direction in which the partition wall extends, and a second opening formed on the other end in the longitudinal direction in which the partition wall extends. The developing device according to claim 1.   The distance between the inner wall surface of the developer storage chamber and the rotation center of the developer transport member is upstream of the boundary portion of the inner wall surface in the rotation direction of the developer transport member. The developing device according to claim 1, wherein a central portion is set to be larger than both end portions in the longitudinal direction.   4. A process cartridge comprising an image carrier, wherein the developer carrier is capable of developing an electrostatic image on the surface of the image carrier, and is attachable to and detachable from an image forming apparatus. A process cartridge comprising the developing device according to the item. An image forming unit for forming an image on a recording material;
A developing device according to any one of claims 1 to 3,
An image forming apparatus comprising:

Images