JP4739431B2 - Developing device and image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus having a function of forming an image on a recording material such as a sheet, and a developing device applied to the image forming apparatus.

  In an image forming apparatus such as a printer using an electrophotographic image forming system (electrophotographic process), an electrophotographic photoreceptor (hereinafter referred to as a photoreceptor) as an image carrier is uniformly charged. Next, an electrostatic latent image is formed on the photosensitive member by selectively exposing the charged photosensitive member. Next, the electrostatic latent image formed on the photoreceptor is visualized as a toner image with toner as a developer. Then, the toner image formed on the photosensitive member is transferred to a recording material such as recording paper or a plastic sheet, and further, heat or pressure is applied to the toner image transferred onto the recording material, whereby the toner image is transferred to the recording material. The image is recorded on the image.

  In recent years, color image forming apparatuses that form color images using a plurality of color developers have become widespread. The color image forming apparatus is a so-called in-line in which photoconductors corresponding to image forming operations using a plurality of color developers are arranged in a line along the surface movement direction of a transfer target to which a toner image is transferred. A type of color image forming apparatus is known. The in-line method is a preferable image forming method in that it can easily meet demands such as an increase in image forming speed and development to a multifunction printer.

  In some inline type color image forming apparatuses, a plurality of photosensitive members are arranged in a line in a direction (for example, a horizontal direction) intersecting a vertical direction (gravity direction). Further, there has been proposed a structure in which a plurality of photosensitive members are disposed below an intermediate transfer member as a transfer member or a recording material carrier that transports a recording material as a transfer member (see Patent Document 1).

  As described above, when the photosensitive member is disposed below the intermediate transfer member or the recording material carrier, the intermediate transfer member or the recording material carrier is sandwiched in the image forming apparatus main body, for example, a fixing device and a developing device ( Alternatively, the exposure apparatus can be arranged at a position away from the exposure apparatus. Therefore, there is an advantage that the developing device (or the exposure device) is hardly affected by the heat of the fixing device.

JP 2003-173084 A

  By the way, in general, a developing device is provided with a developer carrying member for supplying a developer to a photosensitive member, a developer supply member for supplying a developer to the developer carrying member, and the like, and a supply to the developing chamber. And a developer storage chamber for storing the developer to be used.

  As described above, when the photosensitive member is disposed below the intermediate transfer member or the recording material carrier, in the developing device, gravity is transferred from the developer containing chamber to the developing chamber located above the developer containing chamber. In some cases, it may be necessary to transport the developer against and to temporarily store the developer in the developing chamber. The developer temporarily stored in the developing chamber is supplied to the developer supply member.

Here, in Patent Document 1, a developer receiving member is provided below the developer supply member. Then, in the region formed between the developer receiving member and the developer supply member, the developer transported from the developer storage chamber located below is temporarily stored, and the developer is supplied to the developer supply member. Supply.

  However, in such a configuration, since there is no means for stirring the temporarily stored developer, there is a concern that the developer may be packed between the developer receiving member and the developer supply member. When packing occurs, the supply of the developer to the developer supply member is insufficient, and a phenomenon in which the developer does not fall locally on the output image, that is, a so-called image blank is likely to occur.

  On the other hand, a method of arranging a developer stirring member in the developing chamber and stirring the developer temporarily stored in the developing chamber can be considered.

  However, when the developer in the developing chamber is sufficiently stirred, the developer in the vicinity of the opening connecting the developing chamber and the developer containing chamber also flows under the influence of stirring. For this reason, there is a concern that the amount of the developer falling from the developing chamber to the developer containing chamber through the opening increases and a sufficient amount of developer cannot be temporarily stored in the developing chamber. Even in such a case, the supply of the developer to the developer supply member is insufficient, leading to the occurrence of image defects such as image blanking.

  The present invention has been made in view of the above circumstances, and in a configuration in which the developer is supplied to the developing chamber against gravity, by stirring the developer and temporarily storing a sufficient amount of developer, It is an object of the present invention to improve the supply of developer to the developer supply member and suppress the occurrence of image blanking.

In order to achieve the above object, the present invention provides:
A developer storage chamber for storing the developer;
A development chamber provided above the developer storage chamber, to which a developer is supplied from the developer storage chamber;
The developer accommodated in the developer accommodating chamber is conveyed against gravity and is opened through an opening provided in a partition wall that separates the developer accommodating chamber and the developing chamber. A developing device supplied to the developing chamber,
A developer carrying member that is rotatably provided and carries the developer in the developing chamber;
A developer supply member that is rotatably provided in the developing chamber and supplies the developer supplied through the opening to the developer carrier;
In a developing device having
A developer stirring member that is rotatably provided in the developing chamber and conveys the developer supplied through the opening while stirring;
The developer stirring member is rotatably provided between the opening and the developer supply member in the developing chamber,
The upper end of the first rotation region formed by the locus of the developer supply member when the developer supply member rotates is relative to the partition wall portion located below the developer stirring member in the opening. Located above the horizontal plane including the opening edge located at the nearest position,
When the developer stirring member rotates, the upper end of the second rotation region formed by the locus of the developer stirring member is below the horizontal plane including the opening edge, and the lower end of the first rotation region is Located above the horizontal plane
The rotation direction of the developer stirring member is a direction from the lower side to the upper side on the opening side.

According to the present invention, in the configuration in which the developer is supplied to the developing chamber against gravity, the developer to the developer supply member is temporarily stored while stirring the developer while the developer is stirred. It is possible to improve the supply and suppress the occurrence of white spots in the image.

1 is a cross-sectional view illustrating a schematic configuration of an image forming apparatus according to Embodiment 1. FIG. 3 is a cross-sectional view illustrating a schematic configuration of a process cartridge according to Embodiment 1. FIG. 1 is a cross-sectional view illustrating a schematic configuration of a developing device according to Embodiment 1. FIG. 3 is a perspective view illustrating a schematic configuration of a stirring member in Embodiment 1. FIG. FIG. 6 is a diagram for illustrating a toner surface temporarily stored in a developing chamber in Embodiment 1. 5 is a diagram for explaining a partition wall that separates a developing chamber and a toner storage chamber in Embodiment 1. FIG. 2 is a cross-sectional view illustrating a schematic configuration of a developing device of Comparative Example 1. FIG. 10 is a cross-sectional view showing a schematic configuration of a developing device of Comparative Example 2. FIG. 10 is a cross-sectional view illustrating a schematic configuration of a developing device of Comparative Example 3. FIG. 6 is a cross-sectional view illustrating a schematic configuration of a developing device according to Embodiment 2. FIG. In Example 2, it is a figure for demonstrating contact | abutting with a stirring member and a contact member. 6 is a cross-sectional view illustrating a schematic configuration of a developing device according to Embodiment 3. FIG. 6 is a cross-sectional view illustrating a schematic configuration of a developing device according to Embodiment 4. FIG.

  DETAILED DESCRIPTION Exemplary embodiments for carrying out the present invention will be described in detail below with reference to the drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described in this embodiment should be appropriately changed according to the configuration of the apparatus to which the invention is applied and various conditions. It is not intended to limit the scope to the following embodiments.

  The present invention relates to an image forming apparatus that 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.

  First, an overall configuration and operation of an electrophotographic image forming apparatus will be described as an embodiment of an image forming apparatus to which the present invention can be applied.

  FIG. 1 is a cross-sectional view illustrating a schematic configuration of an image forming apparatus 100 according to the present exemplary embodiment. The image forming apparatus 100 is a full-color laser beam printer that employs an inline method or an intermediate transfer method, and can form a full-color image on a recording material (for example, recording paper, plastic sheet, cloth, etc.) in accordance with image information. The image information is input to the image forming apparatus main body from an image reading apparatus connected to the image forming apparatus main body or a host device such as a personal computer connected to the image forming apparatus main body so as to be communicable.

  In FIG. 1, an image forming apparatus 100 forms first and first images for forming images of yellow (Y), magenta (M), cyan (C), and black (K), respectively, as a plurality of image forming units. 2, second and third image forming units SY, SM, SC, and SK. In the present embodiment, the first to fourth image forming units SY, SM, SC, and SK are arranged in a row in a direction that intersects the vertical direction.

In this embodiment, the configurations and operations of the first to fourth image forming units are substantially the same except that the colors of the images to be formed are different. Therefore, in the following description, if no particular distinction is required, 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 the summary I will explain it.

  In this embodiment, the image forming apparatus 100 includes four drum-type electrophotographic photosensitive members (hereinafter referred to as photosensitive drums) 1 arranged in parallel in a direction intersecting the vertical direction as a plurality of image carriers. The photosensitive drum 1 is rotationally driven in a direction indicated by an arrow A (clockwise) by a driving unit (not shown). A charging device 2 and an exposure device 3 are disposed around the photosensitive drum 1. Here, the charging device 2 includes a charging roller (described later), and is a charging unit that uniformly charges the surface of the photosensitive drum 1. The exposure device 3 includes a laser driver, a laser diode, a polygon mirror, an optical lens system, and the like, and is an exposure unit that irradiates a laser beam based on image information to form an electrostatic latent image on the photosensitive drum 1. . A developing device 4 and a cleaning member 6 are disposed around the photosensitive drum 1. Here, the developing device 4 includes a non-magnetic one-component toner (hereinafter referred to as toner) as a developer, and develops the electrostatic latent image as a toner image (performs a developing action on the image carrier). Means. The cleaning member 6 is a cleaning unit that removes toner (transfer residual toner) remaining on the surface of the photosensitive drum 1 after transfer.

  Further, an intermediate transfer belt 5 as an intermediate transfer body for transferring the toner image on the photosensitive drum 1 onto the recording material P is disposed opposite to the four photosensitive drums 1. In the rotation direction of the photosensitive drum 1, the charging position by the charging device 2, the exposure position by the exposure device 3, the development position by the developing device 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 this embodiment, the developing device 4 includes a developing roller (described later) as a developer carrying member, and performs reverse development by bringing the developing roller into contact with the photosensitive drum 1. That is, in this embodiment, the developing device 4 is a portion where the charge is attenuated by exposing the toner charged to the same polarity as the charging polarity of the photosensitive drum 1 (negative polarity in this embodiment) on the photosensitive drum 1. It is made to adhere to (image part or exposure part). As a result, the electrostatic latent image on the photosensitive drum 1 is developed.

  In this embodiment, the photosensitive drum 1 and the charging device 2, the developing device 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. is doing. The process cartridge 7 can be attached to and detached from the image forming apparatus 100 via mounting means such as a mounting guide and a positioning member provided in the image forming apparatus main body. In this embodiment, the process cartridges 7 for the respective colors all have the same shape, and the process cartridges 7 for the respective colors have yellow (Y), magenta (M), cyan (C), and black, respectively. Each color toner of (K) is stored. However, in this embodiment, the process cartridge will be described, but the present invention is not limited to this. For example, the developing device 4 may be configured to be fixed to the image forming apparatus main body, or the developing device 4 may be independently formed into a cartridge and detachable from the image forming apparatus main body.

  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) in the figure. The intermediate transfer belt 5 is stretched around a plurality of support members (a driving roller 51, a secondary transfer counter roller 52, and a driven roller 53).

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 nip (primary transfer nip) at the primary transfer portion N1 where the intermediate transfer belt 5 and the photosensitive drum 1 are in contact with each other. A voltage 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 (not shown) as a primary transfer bias applying unit. 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, and a nip (secondary transfer nip) is formed in the secondary transfer portion N <b> 2 where the intermediate transfer belt 5 and the secondary transfer roller 9 contact. ). A voltage 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 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) onto the recording material P. Here, 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 device 2. Next, the uniformly charged surface of the photosensitive drum 1 is scanned and exposed by a laser beam corresponding to the image information emitted from the exposure device 3, and the electrostatic latent image according to the image information is exposed on the photosensitive drum 1. Is formed. Next, the electrostatic latent image formed on the photosensitive drum 1 is developed as a toner image by the developing device 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, when forming a full-color image, the process is sequentially performed in the first to fourth image forming units SY, SM, SC, and SK, and the toner images of the respective colors are sequentially superimposed on the intermediate transfer belt 5. Primary transcription.

  Thereafter, the recording material P is conveyed to the secondary transfer portion N2 in synchronization with the movement of the intermediate transfer belt 5. The four-color toner images on the intermediate transfer belt 5 are collectively transferred onto the recording material P by the action of the secondary transfer roller 9 in contact with the intermediate transfer belt 5 via the recording material P. Is done.

  The recording material P onto which the toner image has been transferred is conveyed to a fixing device 10 as a fixing unit. In the fixing device 10, heat and pressure are applied to the recording material P, and the toner image is fixed on the recording material P.

  The primary transfer residual toner remaining on the photosensitive drum 1 after the primary transfer step is removed by the cleaning member 6 and collected in a removed toner chamber (described later). 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 one or some (not all) desired image forming units.

  Next, the overall configuration and operation of the process cartridge 7 mounted on the image forming apparatus 100 of the present embodiment will be described. In the description of the present embodiment, the terms indicating the direction of up, down, vertical, and horizontal in the configuration and operation of the developing device or the process cartridge are viewed in their normal use state unless otherwise specified. Indicates the direction when That is, the normal use state of the developing device or the process cartridge is a state in which the developing device or the process cartridge is properly attached to the properly disposed image forming apparatus main body and can be used for an image forming operation. Moreover, in the following description, the longitudinal direction used with respect to the member provided rotatably is assumed to mean the rotation axis direction (rotation axis direction) of the member.

  FIG. 2 is a cross-sectional (main cross-sectional) view showing a schematic configuration of the process cartridge 7 according to the present embodiment, and shows a cross-section orthogonal to the longitudinal direction (rotation axis direction, rotation axis direction) of the photosensitive drum 1. . In the present embodiment, the configuration and operation of the process cartridge 7 for each color are substantially the same except for the type (color) of the toner contained therein.

  In the figure, a process cartridge 7 has a photosensitive unit 13 having a photosensitive drum 1 and the like, and a developing device 4 having a developing roller 17 and the like.

  The photoconductor unit 13 has a cleaning frame 14 as a frame that supports various elements in 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 the arrow A (clockwise) in accordance with the image forming operation by the driving force of a driving motor (not shown) as a driving unit (driving source).

  The photosensitive unit 13 is provided with a charging roller 12 and a cleaning member 6 so as to be in contact with the peripheral surface of the photosensitive drum 1. Then, the transfer residual toner removed from the surface of the photosensitive drum 1 by the cleaning member 6 is configured to fall into a removed toner chamber 14 a formed in the cleaning frame 14.

  A charging roller bearing 15 is attached to the cleaning frame 14 so as to be movable in the direction indicated by the arrow C along a line passing through the rotation center (rotation shaft) of the charging roller 12 and the rotation center of the photosensitive drum 1. It has been. A rotation shaft 12a of the charging roller 12 is rotatably attached to the charging roller bearing 15. The charging roller 12 is brought into contact with the circumferential surface of the photosensitive drum 1 when the charging roller bearing 15 is urged toward the photosensitive drum 1 by a charging roller pressing spring 16 as an urging means.

  On the other hand, the developing device 4 includes a developing frame 18 as a frame that supports various elements in the developing device 4. The developing frame 18 includes a developing chamber 18b and a toner storage chamber 18a as a developer storage chamber provided vertically below the developing chamber 18b. The toner storage chamber 18a and the development chamber 18b communicate with each other through the opening 18c above the toner storage chamber 18a.

  Non-magnetic one-component toner as a developer is stored in the toner storage chamber 18a. In the toner storage chamber 18a, a toner transport member 22 as a developer transport means is rotatably provided. The toner conveying member 22 is rotatably supported by the developing frame 18 that forms the toner storage chamber 18a at both ends in the longitudinal direction. The toner conveying member 22 is rotationally driven in the direction indicated by an arrow G (clockwise) by a driving unit (drive source) (not shown). The toner transport member 22 agitates the toner stored in the toner storage chamber 18a and transports (supplies) the toner to the developing chamber 18b provided above the toner storage chamber 18a through the opening 18c. . Therefore, it is necessary to convey the toner against the gravity from the toner storage chamber 18a to the developing chamber 18b. In this embodiment, the toner storage chamber 18a and the developing chamber 18b are integrally formed, but the present invention is not limited to this. For example, it may be configured as a developer container (toner cartridge) having only the toner storage chamber 18a and the toner transport member 22 and detachable from the image forming apparatus main body and the development chamber 18b.

The developer chamber 18b is a developer carrier that carries and transports the toner in the developer chamber 18b, and is a developer carrier that can rotate in the direction of the arrow D (counterclockwise) in the direction of the figure in contact with the photosensitive drum 1. The developing roller 17 is provided. In the present embodiment, the developing roller 17 and the photosensitive drum 1 are rotated 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 opposite portion (contact portion). To do. The developing roller 17 is rotatably supported by the developing frame 18 at both ends in the longitudinal direction via a developing side plate 19 (19R, 19L). Here, the development side plates 19 (19R, 19L) are respectively attached to both ends of the development frame 18. In this embodiment, the developing roller 17 is disposed in contact with the photosensitive drum 1. However, the present invention is not limited to this. For example, the developing roller 17 is spaced from the photosensitive drum 1 by a predetermined distance. The structure etc. which adjoin and arrange | position may be sufficient.

  In the developing chamber 18b, a supply roller 20 is disposed as developer supply means (developer supply member) that rotates in the direction indicated by the arrow E (counterclockwise). Here, the supply roller 20 contacts the peripheral surface of the developing roller 17. In this embodiment, 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 facing portion (contact portion). The supply roller 20 supplies the toner in the developing chamber 18 b onto the developing roller 17 and also acts to peel off the toner remaining on the developing roller 17 without being used for development from the developing roller 17.

  In the developing chamber 18b, a regulating blade 21 as a layer thickness regulating means for regulating the layer thickness of the toner supplied onto the developing roller 17 by the supply roller 20 is disposed. Here, the regulating blade 21 comes into contact with the peripheral surface of the developing roller 17.

  The developing chamber 18b is provided with an agitating member 25 as a developer agitating means (developer agitating member) that is rotatably supported by the developing frame 18. As will be described in detail later, the agitating member 25 is conveyed against the gravity from the toner storage chamber 18a, agitates the toner temporarily stored in the developing chamber 18b, and supplies (conveys) the toner to the supply roller 20. To act.

  Then, the developing device 4 is attached to the photosensitive unit 13 with a coupling shaft 23 (23R, 23L) fitted in a hole 19a (19Ra, 19La) provided in the developing side plate 19 (19R, 19L) as a center. It is coupled so as to be able to swing (move).

  At the time of image formation, the developing device 4 is urged by a developing device pressing spring 24 as an urging means, and rotates in the illustrated arrow F direction (clockwise) about the coupling shaft 23. As a result, the developing roller 17 comes into contact with the photosensitive drum 1.

  Further, at the time of image formation, the toner accommodated in the toner accommodating chamber 18a is stirred by the toner conveying member 22 and conveyed against the gravity through the opening 18c to the developing chamber 18b. The toner supplied from the toner storage chamber 18a is temporarily stored in the development chamber 18b. Next, the toner is supplied to the supply roller 20 while being stirred by the stirring member 25. Next, the toner supplied to the supply roller 20 is carried and conveyed as the supply roller 20 rotates, and is supplied to the surface of the developing roller 17 at a portion (contact portion) between the supply roller 20 and the developing roller 17. Next, the toner supplied onto the developing roller 17 is carried and conveyed along with the rotation of the developing roller 17, and is frictionally charged and the layer thickness is regulated at the contact position between the developing roller 17 and the regulating blade 21. The thinned toner on the developing roller 17 is carried and conveyed along with the rotation of the developing roller 17, and on the photosensitive drum 1 at a portion (contact portion) between the developing roller 17 and the photosensitive drum 1. The formed electrostatic latent image is developed to form a toner image. Further, the toner that has not been developed on the developing roller 17 is peeled off from the developing roller 17 by the supply roller 20.

  In this embodiment, the toner is prepared by a suspension polymerization method including a binder resin and a charge control agent, and is made to have negative chargeability by adding a fluidizing agent or the like as an external additive. Used. However, the present invention is not limited to this. For example, a toner prepared by using another polymerization method such as a pulverization method or an emulsion polymerization method may be used.

Next, the toner stirring configuration in the developing chamber 18b of the developing device 4 according to the present embodiment will be described. FIG. 3 is a cross-sectional (main cross-sectional) view illustrating a schematic configuration of the developing device 4 according to the present embodiment. FIG. 4 is a perspective view illustrating a schematic configuration of the stirring member 25 in the developing device 4 according to the present embodiment. FIGS. 5A and 5B are partial cross-sectional views of the schematic configuration of the developing device 4 according to the present embodiment, and are diagrams for explaining the toner surface temporarily stored in the developing chamber 18b.

  In FIG. 3, a stirring member 25 is rotatably provided in the developing chamber 18b. The stirring member 25 is rotatably supported by the developing frame 18 that forms the developing chamber 18b at both ends in the longitudinal direction. The agitating member 25 is rotationally driven in the direction indicated by the arrow H (clockwise) by a driving means (drive source) (not shown).

  The agitating member 25 has a flexible sheet portion 25a as an agitating portion for agitating the toner, and a rotatable agitating support shaft (rotating shaft) to which the sheet portion 25a is attached and for receiving a rotational driving force. 25b. Here, the sheet portion 25a includes a flexible portion having flexibility provided in a distal end region on the outer diameter side of the stirring member 25 (an end region, a region on the outermost side of the stirring member 25). .

  The agitation support shaft 25b is disposed over substantially the entire region in the longitudinal direction of the developing chamber 18b, substantially parallel to the longitudinal direction of the developing roller 17 and the supply roller 20. The sheet portion 25a is a continuous sheet (plate-like member) that extends over substantially the entire region in the longitudinal direction of the stirring support shaft 25b. And the sheet | seat part 25a is attached to the stirring support shaft 25b in the one end part of the direction (rotation radial direction, short direction) substantially orthogonal to the longitudinal direction of the stirring support shaft 25b. In this example, as shown in FIG. 4, a quadrangular columnar stirring support shaft 25b having a square shape in cross section perpendicular to the longitudinal direction of the stirring support shaft 25b was used. The sheet portions 25a (25a1, 25a1, 25a1, 25a1, 25a1, 25a1, 25a1, 25a1, 25a1, 25a1, 25a1, 25a1, 25a1, and 25b are arranged so that the directions of the free ends thereof are different from each other by two directions facing each other in the direction substantially orthogonal to the longitudinal direction of the stirring support shaft 25b 25a2) was attached. However, the present invention is not limited to this, and for example, the stirring support shaft 25b may have a circular or other polygonal cross-sectional shape perpendicular to the longitudinal direction of the stirring support shaft 25b. The number of sheet portions 25a may be any number as long as it is one or more.

  The sheet portion 25a can be suitably manufactured using a flexible resin sheet such as a polyethylene terephthalate film, a polyester film, a polyphenylene sulfide film, or a polycarbonate film. The thickness of the sheet portion 25a is preferably 50 μm to 250 μm. The stirring support shaft 25b is formed using, for example, a resin material or a metal material. In this example, a polyethylene terephthalate film having a thickness of 50 μm was used for the sheet portion 25a. The stirring support shaft 25b was made of a resin material. In the present embodiment, the agitation member 25 is composed of a flexible sheet portion 25a and a rotatable agitation support shaft 25b to which the sheet portion 25a is attached, but is not limited thereto. It is not a thing.

  The stirring member 25 and the opening 18 c are provided on the opposite side of the facing portion (contact portion) between the supply roller 20 and the developing roller 17 with the supply roller 20 interposed therebetween. The stirring member 25 is provided between the supply roller 20 and the opening 18c. The upper end T1 of the rotation region of the supply roller 20 is provided above a horizontal plane passing (including) the lower end T2 of the opening 18c (that is, the lowest point of the opening 18c). Here, the rotation region of the supply roller 20 refers to a region formed by the locus of the supply roller 20 when the supply roller 20 rotates, and corresponds to a first rotation region. Further, the rotation region upper end T3 of the stirring member 25 is provided above a horizontal plane passing through the rotation region lower end T4 of the supply roller 20. Here, the rotation region of the stirring member 25 refers to a region formed by the locus of the stirring member 25 when the stirring member 25 rotates, and corresponds to a second rotation region.

  In other words, in the present embodiment, the stirring member 25 is provided between the supply roller 20 and the opening 18c relatively near the supply roller 20 and the opening 18c. Thereby, the action of the stirring member 25 can be exerted on the toner near the supply roller 20 and the opening 18c. Therefore, the toner supplied to the developing chamber 18 b through the opening 18 c is efficiently supplied to the supply roller 20 while being sufficiently stirred by the stirring member 25.

  Moreover, the rotation area upper end T3 of the stirring member 25 is provided below the horizontal plane passing through the lower end T2 of the opening 18c. According to this, it is possible to reduce a large amount of toner temporarily stored in the developing chamber 18b from the opening 18c to the toner storage chamber 18a as the stirring member 25 rotates. Therefore, a sufficient amount of toner can be temporarily stored in the developing chamber 18b.

  The stirring member 25 and the supply roller 20 are arranged so that the sheet portion 25a of the stirring member 25 and the surface of the supply roller 20 move in the same direction (in this embodiment, the direction from the upper side to the lower side). Rotate. Therefore, the stirring member 25 rotates in a direction in which the sheet portion 25a moves from the lower end to the upper end of the opening 18c at the portion facing the opening 18c (opening side). In other words, in this embodiment, the stirring member 25 rotates so that the toner supplied to the developing chamber 18b through the opening 18c is moved toward the supply roller 20. Therefore, as shown in FIG. 5A, the surface of the toner temporarily stored in the developing chamber 18b (the surface of the toner as a group) approaches the supply roller 20 from the opening 18c, and the lower end of the opening 18c. Above T2. As a result, the amount of toner returning from the opening 18c to the toner storage chamber 18a is reduced. In addition, since the amount of toner falling from the opening 18c is small, the toner conveyed against the gravity from the toner storage chamber 18a to the developing chamber 18b is less likely to be blocked by the toner. Therefore, a sufficient amount of toner can be temporarily stored in the developing chamber 18b. Further, the surface of the toner temporarily stored in the developing chamber 18b (the surface of the toner as a group) can be raised from the lower end T2 of the opening 18c. As a result, the contact area between the surface of the supply roller 20 and the toner increases, and the effect of improving the toner supply to the supply roller 20 is obtained.

  The developing device frame 18 has a partition wall 26 as a developing chamber partition wall that separates the developing chamber 18b and the toner storage chamber 18a. 6A and 6B are partial cross-sectional views of a schematic configuration of the developing device 4 according to the present embodiment, and are diagrams for explaining the partition wall 26. FIG. In the present embodiment, the partition wall 26 includes a first partition wall surface 26a, a second partition wall surface 26b, and a third partition wall surface 26c. An opening 18c is provided in the first partition wall surface 26a. The stirring member 25 is provided above the second partition wall surface 26b in the vertical direction, and the second partition wall surface 26b has a cross-sectional shape orthogonal to the longitudinal direction of the stirring member 25 so as to protrude substantially downward. It is configured. A supply roller 20 and a regulation blade 21 are provided above the third partition wall surface 26c in the vertical direction. The first partition wall surface 26a and the second partition wall surface 26b are configured to be continuous via the boundary point c1. Furthermore, the second partition wall surface 26b and the third partition wall surface 26c are configured to be continuous via a boundary point c2. Here, the lower end T2 of the opening 18c is relative to the portion of the second partition wall surface 26b located below the stirring member 25 in the opening 18c (for example, the lowest point c3 of the second partition wall surface 26b). It corresponds to the opening edge located at the closest position.

In the continuous partition from the lowest point c3 of the second partition wall surface 26b located below the rotation center of the stirring member 25 to the lower end T2 of the opening 18c, the inclination angle formed by the partition wall surface and the horizontal plane is 90. It is preferable to have a portion set at a degree or more. Further, it is more preferable that the portion is set to an angle exceeding 90 degrees. This is to reduce the amount of toner stirred by the stirring member 25 from being returned from the opening 18c to the toner containing chamber 18a along the partition wall in the developing chamber 18b (developing chamber). In the present embodiment, as shown in FIG. 6A, the inclination angle α formed by the tangent line of the first partition wall surface 26a passing through the boundary point c1 and the horizontal plane is set to 90 degrees or more. Here, in this embodiment, as shown in FIG. 6A, the inclination angle α formed between the tangent to the partition wall surface 26a and the horizontal plane is the size of the angle formed with the horizontal plane outside the developing chamber 18b. .

  In addition, in the continuous partition from the lowest point c3 of the second partition surface 26b located below the rotation center of the stirring member 25 to the lower end T2 of the opening 18c, the inclination angle formed by the partition surface and the horizontal surface is the toner. It is preferable to have a portion set larger than the angle of repose. This is because the effect of collecting the toner in the vicinity of the stirring member 25 and the supply roller 20 is obtained by making the toner easily fall along the partition wall surface. In this embodiment, for example, as shown in FIG. 6B, the inclination angle β formed by the tangent line of the second partition wall surface 26b passing through the boundary point c1 and the horizontal plane is set larger than the repose angle of the toner. Yes. On the other hand, the inclination angle formed between the tangent line of the second partition wall surface 26b passing through the lowest point c3 of the second partition wall surface 26b and the horizontal plane is set smaller than the repose angle of the toner. Then, between the boundary point c1 and the lowest point c3 of the second partition wall surface 26b, the inclination angle formed by the partition wall surface and the horizontal surface changes from a value larger than the repose angle of the toner to a smaller value. Here, in the present embodiment, as shown in FIG. 6B, the inclination angle β formed between the tangent to the partition wall surface 26b and the horizontal plane is the size of the angle formed with the horizontal plane outside the developing chamber 18b. .

  In the present embodiment, the sheet portion 25a of the stirring member 25 and the partition wall 26 (mainly the first partition wall surface 26a and the second partition wall surface 26b) are set to be in a non-contact state (proximity state). ing.

  In the present embodiment, the image forming apparatus 100 is described as an intermediate transfer type having an intermediate transfer body, but the present invention is not limited to this. For example, the toner image formed on the photosensitive drum 1 may be of a type in which the toner image is directly transferred onto the recording material P carried on the recording material carrier. In this type of image forming apparatus, instead of the intermediate transfer belt 5 described above, a conveyance belt formed by an endless belt as a recording material carrier is disposed, and a process cartridge or the like is provided below the conveyance belt. An image forming unit may be arranged. At that time, in the developing device 4, it may be necessary to convey the toner against gravity, so the present invention works effectively.

[Comparative Example 1]
Comparative Example 1 is basically the same as Example 1, except for the following points. This comparative example is different in that the stirring member 25 is not provided in the developing chamber 18b.

  FIG. 7 is a cross-sectional (main cross-sectional) view showing a schematic configuration of the developing device 4 according to this comparative example. In this comparative example, the partition wall 26 includes a first partition wall surface 26d provided with an opening 18c, and a second partition wall surface 26e provided with a supply roller 20 and a regulation blade 21 on the upper side in the vertical direction. Here, the second partition wall surface 26e has a portion where the inclination angle γ formed by the tangent line of the second partition wall surface 26e and the horizontal plane is set larger than the repose angle of the toner. As a result, the toner tends to collapse along the partition wall surface, and the toner supplied to the developing chamber 18b through the opening 18c is collected near the supply roller 20 and temporarily stored.

[Comparative Example 2]
Comparative Example 2 is basically the same as Example 1, except for the following points. In this comparative example, the rotation region upper end T3 of the stirring member 25 is different from the horizontal plane passing through the lower end T2 of the opening 18c.

  FIG. 8 is a cross-sectional (main cross-sectional) view showing a schematic configuration of the developing device 4 according to this comparative example. In this comparative example, the rotation center of the stirring member 25 is provided in the vicinity of a horizontal plane passing through the lower end T2 of the opening 18c. Therefore, the rotation region upper end T3 of the stirring member 25 is above the horizontal plane passing through the lower end T2 of the opening 18c.

[Comparative Example 3]
Comparative Example 3 is basically the same as Example 1, except for the following points. In this comparative example, the rotation direction of the stirring member 25 is different.

  FIG. 9 is a cross-sectional (main cross-sectional) view showing a schematic configuration of the developing device 4 according to this comparative example. In this comparative example, the stirring member 25 rotates in a direction in which the sheet portion 25a moves from the upper end to the lower end of the opening 18c at the portion facing the opening 18c. Further, in accordance with the rotation direction of the agitating member 25, the sheet portion 25a is provided such that the respective free ends are on the opposite side of the first embodiment across the mounting surface to the agitation support shaft 25b. .

  Example 2 is basically the same as Example 1, but differs in the following points. The present embodiment is different in that an abutting member 27 that abuts on the sheet portion 25a of the stirring member 25 is provided on the second partition wall surface 26b. FIG. 10 is a cross-sectional (main cross-sectional) view illustrating a schematic configuration of the developing device 4 according to the present embodiment. FIG. 11 is a partial cross-sectional view of the schematic configuration of the developing device according to the present embodiment, and is a view for explaining the contact between the stirring member 25 and the contact member 27. In the present embodiment, constituent parts different from those in the first embodiment will be described, and description of constituent parts similar to those in the first embodiment will be omitted.

  The contact member 27 is provided between the stirring member 25 and the supply roller 20 in the partition wall 26. In this embodiment, the contact member 27 is formed between the lowest point c3 and the boundary point c2 of the second partition surface 26b. It is provided in between. Further, in the present embodiment, the contact member 27 is a member whose cross-sectional shape orthogonal to the longitudinal direction of the stirring member 25 is substantially convex. However, it is not limited to this.

  As shown in FIG. 11, the contact member 27 has a first contact member surface 27 a that faces the stirring member 25, and a second contact member surface 27 b that faces the supply roller 20. As the stirring member 25 rotates, the sheet portion 25a and the first contact member surface 27a come into contact with each other. By this contact, the toner is pushed out, and the toner flows toward the supply roller 20 in the region near the supply roller 20. Therefore, an effect of efficiently supplying toner to the supply roller 20 can be obtained. Here, the first contact member surface 27a corresponds to a contact portion that the sheet portion 25a contacts and bends the sheet portion 25a. Further, the second contact member surface 27 b corresponds to a guide portion that guides a part of the toner conveyed by the sheet portion 25 a to the supply roller 20.

  In the present embodiment, the contact member 27 is configured separately from the second partition wall surface 26b. However, the present invention is not limited to this. For example, the contact member 27 is configured integrally with the second partition wall surface 26b. Also good. In this embodiment, the contact member 27 is provided between the lowermost point c3 and the boundary point c2 of the second partition wall surface 26b, but is not limited to this. For example, even if it is not on the second partition wall surface 26 b, it is sufficient if the stirring member 25 abuts so that the toner can flow toward the supply roller 20 in the region near the supply roller 20.

  Example 3 is basically the same as Example 2, but differs in the following points. In the present embodiment, a continuous partition from the lowest point c3 of the second partition wall surface 26b located below the rotation center of the stirring member 25 to the lower end T2 of the opening 18c has a portion that contacts the stirring member 25. That is different. FIG. 12 is a cross-sectional (main cross-sectional) view illustrating a schematic configuration of the developing device 4 according to the present embodiment. In the present embodiment, constituent parts different from those in the second embodiment will be described, and description of constituent parts similar to those in the second embodiment will be omitted.

In the present embodiment, the stirring member 25 having a long free length of the sheet portion 25a is provided in the developing chamber 18b. Therefore, as the stirring member 25 rotates, the sheet portion 25 a
Between the lowest point c3 of 6b and the boundary point c1, it has the part which contacts the 2nd partition wall surface 26b. Thereby, the toner existing between the stirring member 25 and the continuous partition wall from the lowest point c3 of the second partition wall surface 26b to the lower end T2 of the opening 18c can be efficiently conveyed to the vicinity of the supply roller 20. it can. Therefore, the contact area between the surface of the supply roller 20 and the toner increases, and the effect of improving the toner supply to the supply roller 20 can be obtained. Further, the toner supply to the supply roller 20 by the contact between the stirring member 25 and the contact member 27 can be improved.

  In this embodiment, the stirring member 25 having a long free length of the sheet portion 25a is provided in the developing chamber 18b, so that the stirring is performed between the lowest point c3 of the second partition wall surface 26b and the boundary point c1. Although the region where the member 25 and the second partition wall surface 26b are in contact with each other is provided, the present invention is not limited to this. For example, the distance from the lowest point c3 to the boundary point c1 of the second partition wall surface 26b and the rotation center of the stirring member 25 is set to be shorter than the rotation radius of the stirring member 25, etc. But you can.

  Next, evaluation of Examples 1 to 3 and Comparative Examples 1 to 3 will be described.

  For the configurations of Examples 1 to 3 and Comparative Examples 1 to 3, two types of evaluation were performed: (A) image blank evaluation at a toner filling amount of 200 g and (B) image blank evaluation at a toner filling amount of 80 g. As an evaluation image, an A4 size full-scale black image having an image ratio of 100%, which consumes the largest amount of toner, was used. All image evaluations were performed in an environment of 23 ° C. and 50% RH. Hereinafter, each image evaluation will be described individually.

(A) Image blanking evaluation with toner filling amount of 200 g In this image evaluation, first, 200 g of toner corresponding to 8000 A4 size images with an image ratio of 5% is filled in the toner storage chamber 18a. Then, 100 A4 horizontal line images with an image ratio of 1% (specifically, an image that repeats non-printing of 99 dot lines after printing 1 dot line) are output continuously, and then 3 black images are output continuously. did. Then, the white blank image on the third sheet was visually evaluated for image blanking. Here, the horizontal line image and the entire black image were output in the same single color.

The evaluation criteria for image blanking are as follows.
○: No white spot in the image is seen. △: Slight white spot in the image has occurred (a part of the entire black image is slightly white.)
×: Significant white spot in the image (a part or all of the entire black image is markedly white)

(B) Image blanking evaluation at 80 g toner filling amount This image evaluation is basically the same as (A) Image blanking evaluation at 200 g toner filling amount, except for the following points. In this image evaluation, the toner storage chamber 18a is filled with toner, 100 A4 size horizontal line images with an image ratio of 1% are continuously output, and then 400 full-color black images are continuously output. Here, the toner weight in the developing device 4 after the output of 400 full-color black images was measured and found to be 80 g. Then, three full-color black images were continuously output, and the white blank image was visually evaluated for the third full-color black image.

Table 1 shows the image evaluation results of Examples 1 to 3 and Comparative Examples 1 to 3.

  Below, the advantage of this invention is demonstrated by comparing Examples 1-3 and Comparative Examples 1-3.

<Compare Example 1 and Comparative Examples 1-3>
First, the superiority of the present invention will be described by comparing Example 1 and Comparative Examples 1 to 3.

  In Example 1, as compared with Comparative Examples 1 to 3, the evaluation result of image blanking at a toner filling amount of 200 g was better. This is considered as follows.

  In Comparative Example 1, the inclination angle γ formed by the tangent line of the second partition wall surface 26e and the horizontal plane has a portion that is set larger than the repose angle of the toner. Thus, the toner easily collapses along the partition wall surface, and the toner supplied to the developing chamber 18b through the opening 18c is collected near the supply roller 20 and temporarily stored. However, since no stirring member is provided in the developing chamber 18b, packing is likely to occur. As a result, the supply of toner to the supply roller 20 is insufficient, and white spots in the image occur.

  On the other hand, Comparative Examples 2 and 3 have a stirring member 25 in the developing chamber 18b. Therefore, since the toner temporarily stored in the developing chamber 18b is stirred by the stirring member 25, the occurrence of packing is suppressed.

  However, in Comparative Example 2, the rotation region upper end T3 of the stirring member 25 is provided above the horizontal plane passing through the lower end T2 of the opening 18c. Therefore, with the rotation of the stirring member 25, a large amount of toner temporarily stored in the developing chamber 18b is returned from the opening 18c to the toner storage chamber 18a. Therefore, a sufficient amount of toner cannot be temporarily stored in the developing chamber 18b. As a result, the supply of toner to the supply roller 20 is insufficient, and white spots in the image occur.

In Comparative Example 3, the stirring member 25 is provided so as to rotate in a direction in which the sheet portion 25a moves from the upper end to the lower end of the opening 18c at the portion facing the opening 18c. That is, in Comparative Example 3, the agitating member 25 rotates so that the toner supplied to the developing chamber 18b through the opening 18c is moved toward the opening 18c. Therefore, as shown in FIG. 5B, the surface of the toner temporarily stored in the developing chamber 18b (the surface of the toner as a group) approaches the opening 18c from the supply roller 20, and the lower end of the opening 18c. It is above the horizontal plane passing through T2. For this reason, the amount of toner that falls from the opening 18c and returns to the toner storage chamber 18a increases. Further, since the amount of toner falling from the opening 18c is large, the amount of toner that is blocked by the toner and conveyed from the toner storage chamber 18a to the developing chamber 18b against gravity is reduced. Therefore, it is difficult to temporarily store a sufficient amount of toner in the developing chamber 18b. As a result, the supply of toner to the supply roller 20 is insufficient, and white spots in the image occur.

  On the other hand, Example 1 of the present invention first has a stirring member 25 in the developing chamber 18b as in Comparative Examples 2 and 3. Therefore, since the toner temporarily stored in the developing chamber 18b is stirred by the stirring member 25, the occurrence of packing is suppressed.

  Moreover, in Example 1, the rotation area | region upper end T3 of the stirring member 25 is provided below rather than the horizontal surface which passes along the lower end T2 of the opening part 18c. Therefore, it is possible to reduce a large amount of toner temporarily stored in the developing chamber 18b from being returned to the toner storage chamber 18a from the opening 18c as the stirring member 25 rotates. Therefore, a sufficient amount of toner can be temporarily stored in the developing chamber 18b.

  Moreover, in Example 1, the stirring member 25 rotates in a direction in which the sheet portion 25a moves from the lower end to the upper end of the opening portion 18c at the portion facing the opening portion 18c. That is, in Example 1, the stirring member 25 rotates so that the toner supplied to the developing chamber 18b through the opening 18c is moved toward the supply roller 20. Therefore, as shown in FIG. 5A, the surface of the toner temporarily stored in the developing chamber 18b (the surface of the toner as a group) approaches the supply roller 20 from the opening 18c, and the lower end of the opening 18c. Above T2. As a result, the amount of toner returning from the opening 18c to the toner storage chamber 18a is reduced. In addition, since the amount of toner falling from the opening 18c is small, the toner conveyed against the gravity from the toner storage chamber 18a to the developing chamber 18b is less likely to be blocked by the toner. Therefore, a sufficient amount of toner can be temporarily stored in the developing chamber 18b. Further, the surface of the toner temporarily stored in the developing chamber 18b (the surface of the toner as a group) can be raised from the lower end T2 of the opening 18c. As a result, the contact area between the surface of the supply roller 20 and the toner increases, and the supply of toner to the supply roller 20 is improved.

  As described above, in the first embodiment, the toner can be supplied to the supply roller 20 satisfactorily by temporarily storing a sufficient amount of toner while stirring the toner in the developing chamber 18b. Therefore, even when the toner is transported against gravity, the occurrence of image blanking can be suppressed.

<Comparison of Examples 1-3>
Next, in order to explain the effectiveness of the second and third embodiments of the present invention, a comparison is made with the first embodiment.

  In each of Examples 1 to 3, the evaluation result of image blanking at (A) toner filling amount 200 g was good. However, in (B) evaluation of image blanking at a toner filling amount of 80 g, the evaluation results of Examples 2 and 3 were better than those of Example 1. This is considered as follows.

When the amount of toner in the developing device 4 decreases, the amount of toner supplied against the gravity from the toner storage chamber 18a to the developing chamber 18b also decreases. Therefore, it is difficult to temporarily store a sufficient amount of toner in the developing chamber 18b as compared with a case where the amount of toner in the developing device 4 is large. Therefore, in Example 1, image blanking occurred in the evaluation of image blanking at a toner filling amount of 80 g.

  On the other hand, in Example 2, the contact member 27 is provided between the lowest point c3 and the boundary point c2 of the second partition wall surface 26b. As the agitating member 25 rotates, the sheet portion 25a and the first abutting member surface 27a come into contact with each other, so that toner flows toward the supply roller 20 in the region near the supply roller 20. Thereby, the toner can be efficiently supplied to the supply roller 20. Therefore, in Example 2, occurrence of image blanking is suppressed in the evaluation of image blanking at a toner filling amount of 80 g.

  Further, in Example 3, as the stirring member 25 rotates, the portion where the sheet portion 25a comes into contact with the second partition wall surface 26b between the lowest point c3 and the boundary point c1 of the second partition wall surface 26b. Is provided. Thereby, the toner existing between the stirring member 25 and the continuous partition wall from the lowest point c3 of the second partition wall surface 26b to the lower end T2 of the opening 18c can be efficiently conveyed to the vicinity of the supply roller 20. it can. As a result, the contact area between the surface of the supply roller 20 and the toner increases, and the effect of improving the toner supply to the supply roller 20 is obtained. Further, the toner supply to the supply roller 20 by the contact between the stirring member 25 and the contact member 27 can be improved. Therefore, in Example 3, the occurrence of image blanking is further suppressed in the evaluation of image blanking at a toner filling amount of 80 g.

  As described above, in the second and third embodiments, the toner is supplied to the supply roller 20 more efficiently by bringing the stirring member 25 into contact with the contact member 27 and the partition wall surface in the developing chamber 18b. Yes. Therefore, even when the amount of toner in the developing device 4 is small and it is difficult to temporarily store a sufficient amount of toner in the developing chamber 18b, it is possible to suppress the occurrence of image blanking.

  Example 4 is basically the same as Example 3, but differs in the following points. In this embodiment, the developing chamber 18b has a plurality of stirring members. FIG. 13 is a cross-sectional (main cross-sectional) view illustrating a schematic configuration of the developing device 4 according to the present embodiment. In the present embodiment, constituent parts different from those in the third embodiment will be described, and description of constituent parts similar to those in the third embodiment will be omitted.

  In this embodiment, a stirring member 25 as a first developer stirring means (developer stirring member) and a stirring member 28 as a second developer stirring means (developer stirring member) are provided in the developing chamber 18b. Have Here, the stirring member 25 is the same as that of the third embodiment.

  The stirring member 28 is rotatably provided in a region surrounded by the supply roller 20 and the regulating blade 21 and the third partition wall surface 26c. The stirring member 28 is rotatably supported by the developing device frame 18 forming the developing chamber 18b at both ends in the longitudinal direction. The agitating member 28 is rotationally driven in the direction indicated by the arrow I (clockwise) by a driving means (drive source) not shown. In this embodiment, the stirring member 28 is the same as the stirring member 25. However, it is not limited to this. In the present embodiment, the sheet portion 28a of the stirring member 28 and the third partition wall surface 26c have a contact portion.

  The agitating member 28 and the supply roller 20 are arranged so that the sheet portion 28a of the agitating member 28 and the surface of the supply roller 20 move in the same direction (in this embodiment, the direction from the bottom to the top) at the opposing portions. Rotate. Then, the toner is supplied to the supply roller 20 as the stirring member 28 rotates.

  As described above, the toner supply to the supply roller 20 can be more stably performed by increasing the area for supplying the toner to the supply roller 20 using a plurality of stirring members.

DESCRIPTION OF SYMBOLS 4 Developing device 17 Developing roller 18a Toner storage chamber 18b Developing chamber 18c Opening 20 Supply roller 25 Stirring member 26 Partition T1 Upper end of rotation region of supplying roller 20 T2 Lower end of opening 18c T3 Upper end of rotating region of stirring member 25 T4 Bottom rotation area of

Claims (6)

A developer storage chamber for storing the developer;
A development chamber provided above the developer storage chamber, to which a developer is supplied from the developer storage chamber;
The developer accommodated in the developer accommodating chamber is conveyed against gravity and is opened through an opening provided in a partition wall that separates the developer accommodating chamber and the developing chamber. A developing device supplied to the developing chamber,
A developer carrying member that is rotatably provided and carries the developer in the developing chamber;
A developer supply member that is rotatably provided in the developing chamber and supplies the developer supplied through the opening to the developer carrier;
In a developing device having
A developer stirring member that is rotatably provided in the developing chamber and conveys the developer supplied through the opening while stirring;
The developer stirring member is rotatably provided between the opening and the developer supply member in the developing chamber,
The upper end of the first rotation region formed by the locus of the developer supply member when the developer supply member rotates is relative to the partition wall portion located below the developer stirring member in the opening. Located above the horizontal plane including the opening edge located at the nearest position,
When the developer stirring member rotates, the upper end of the second rotation region formed by the locus of the developer stirring member is below the horizontal plane including the opening edge, and the lower end of the first rotation region is Located above the horizontal plane
The developing device according to claim 1, wherein the rotation direction of the developer stirring member is a direction from the lower side to the upper side on the opening side.   A portion of the partition wall from the position below the rotation axis of the developer stirring member to the opening edge has an inclination angle with respect to a horizontal plane, and an angle formed with the horizontal plane outside the developing chamber. The developing device according to claim 1, wherein a portion exceeding 90 degrees is included. A flexible portion having flexibility is provided in a distal end region on the outer diameter side of the developer stirring member,
Of the partition, between the developer agitating member and the developer supply member, the abutment portion where the flexible portion abuts and bends the flexible portion, and the developer conveyed by the flexible portion The developing device according to claim 1, further comprising a contact member having a guide portion that guides a part of the guide to the developer supply member.   A portion of the partition wall from the position below the rotation axis of the developer stirring member to the opening edge has an inclination angle with respect to a horizontal plane, and an angle formed with the horizontal plane outside the developing chamber. 4. The developing device according to claim 1, wherein a portion larger than an angle of repose of the developer supplied to the developing chamber is included. 5.   2. The part of the partition from the position below the rotation axis of the developer stirring member to the opening edge includes a portion where the developer stirring member abuts. 5. The developing device according to any one of 4 above. An image carrier;
The developing device according to any one of claims 1 to 5, which performs a developing action on the image carrier;
An image forming apparatus comprising:

Images