JP4804552B2 - Developing device and process cartridge including the same - Google Patents

Description

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

  Conventionally, an image forming apparatus that forms an image on a sheet material used as a recording medium by an electrophotographic process is known. Such an image forming apparatus includes an image carrier that carries an electrostatic latent image, a developing device that develops the electrostatic latent image on the image carrier as a developer image, and a transfer member that transfers the developer image onto a sheet material. And a fixing device for fixing a developer image on a sheet material by heat.

  In addition, in order to easily perform developer replenishment work and maintenance work to the developing device, a process in which an image carrier, a developing device, a charging member that charges the surface of the image carrier, a cleaning unit, and the like are integrated as a process cartridge. A cartridge system is known. According to the process cartridge system, an image forming apparatus with excellent usability can be provided.

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

In addition, in an in-line image forming apparatus in which a plurality of image carriers are arranged in a row in a direction crossing the vertical direction, the plurality of image carriers are used as intermediate transfer members as transfer targets or sheets for conveying sheet materials. Some are arranged below the material carrier (see Patent Documents 1 and 2). When the image carrier is arranged below the intermediate transfer member or the sheet material carrier in this way, the fixing device and the developing device with the intermediate transfer member or the sheet material carrier sandwiched in the image forming apparatus main body. (Or the exposure apparatus) can be arranged at a position away from each other. Therefore, developing device (or exposure device)
Has the advantage that it is not easily affected by heat generated in the fixing device.

JP 2003-173083 A JP 2008-170951 A

  However, the conventional image forming apparatus has the following problems.

In general, the developing device includes a developer carrier that supplies a developer to the image carrier, a developer supply member that supplies a developer to the developer carrier, and the like. A developer storage chamber for storing the developer to be supplied; Depending on the positional relationship between the development chamber and the developer storage chamber, the developer may be conveyed from the developer storage chamber to the development chamber against gravity. For example, when the image carrier is disposed below the intermediate transfer member or the sheet material carrier as described above, a developer chamber is disposed below the image carrier and a developer storage chamber below the developer chamber due to space limitations. Many patterns are used. That is, in this case, it is necessary to supply the developer against the gravity from the developer storage chamber to the development chamber.

  In Patent Document 1, as a means for transporting a developer from a developer storage chamber to a development chamber disposed above, a flexible member is provided at the tip of a stirring member that stirs the developer in the developer storage chamber. A method for affixing a conveying member formed of a sheet member is disclosed. However, the method disclosed in Patent Document 1 has a problem that it is difficult to reduce the size of the stirring member because the conveying member is attached to the outer end of the stirring member in the radial direction of rotation.

  Further, in the method disclosed in Patent Document 1, the transport member attached to the outer end of the agitating member in the radial direction of rotation holds the developer, and transports the developer to the developer storage chamber in that state to develop the developer. It feeds into the receiving member provided under the agent supply member. Therefore, the supply of the developer to the developer supply member is performed below the developer supply member provided with the receiving member.

  However, if there is no supply means for supplying the developer from below the developer supply member to the developer supply member, the developer carried near the developer supply member is reduced in bulk due to its own weight, etc. A space is generated between the agent supply member and the developer surface. As a result, if the developer is not sufficiently supplied to the surface of the developer supply member and a solid image is output, even if a desired density is obtained at the front end of the image, a thin density occurs from the center to the rear end of the image. There is a high possibility of image defects such as so-called image density tracking failure.

  As described above, in the configuration in which the developer is supplied to the developer supply member from the lower side of the developer supply member, when there is no supply means, a desired density can be obtained with respect to the followability of the image density. It is difficult.

  In Patent Document 1, a receiving member is provided below the developer supply member, one end of the receiving sheet is attached to the receiving member, and the receiving sheet is brought into contact with the lower side of the developer supply member with an appropriate linear pressure. Is disclosed. However, in this case, the developer supplied to the developer supply member is always subjected to a linear pressure between the receiving sheet and the developer supply member, which promotes deterioration of the developer.

  Therefore, the present invention provides a developing device in which a developer storage chamber is disposed below the developer carrier, and a sufficient amount of developer is supplied to the developer carrier to suppress the occurrence of image defects and reduce the size. An object of the present invention is to provide a developing device that can be used and a process cartridge including the developing device.

In order to achieve the above object, the present invention provides:
A developing device used in an image forming apparatus,
A developer carrying member carrying the developer;
A developing chamber provided with the developer carrier;
A developer storage chamber that is disposed below the development chamber and stores a developer to be supplied to the development chamber when the development device is used in the image forming apparatus ;
In the developing device for supplying the developer from the developer accommodating chamber to the developing chamber through an opening formed above the developer accommodating chamber,
In the developer storage chamber,
One end side of the elastic sheet-like developer transport member is supported by a rotatable support shaft, and is provided to rotate in a direction from the lower side of the developer storage chamber toward the opening,
On the inner wall of the developer storage chamber,
In order from the bottom of the developer storage chamber along the rotation direction of the developer transport member,
A deforming portion for deforming the developer conveying member into a bent state by contacting a free end side of the rotating developer conveying member;
Restoring the developer transport member deformed to be in a deformed state without contacting the developer transport member and being deformed at the deformed portion, and having the opening,
An abutting portion that abuts a part of the developer conveying member that moves the restoring portion;
Is formed,
When the developer conveying member rotates and comes out of the deforming portion and moves to the restoring portion, the developer carried between the deformed developer conveying member and the deforming portion is removed from the developing portion. It is possible to fly to the opening with the restoration of the agent conveying member, and
The contact portion is located below the opening portion, and the developer transport member is in contact with the contact portion, and the contact portion serves as a fulcrum of the developer transport member . The region from the contacted portion that contacts the contact portion to the free end can be deformed downstream in the rotational direction.

In the process cartridge of the present invention,
A process cartridge configured to be detachable from the image forming apparatus,
An electrophotographic photoreceptor;
A developer carrying member for carrying a developer for developing the electrostatic latent image formed on the electrophotographic photosensitive member;
A developing chamber provided with the developer carrier;
A developer storage chamber that is disposed below the developing chamber when the process cartridge is mounted on the image forming apparatus and stores the developer supplied to the developing chamber;
In the process cartridge configured to pass the opening formed above the developer storage chamber and supply the developer from the developer storage chamber to the development chamber,
In the developer storage chamber,
One end side of the elastic sheet-like developer transport member is supported by a rotatable support shaft, and is provided to rotate in a direction from the lower side of the developer storage chamber toward the opening,
On the inner wall of the developer storage chamber,
In order from the bottom of the developer storage chamber along the rotation direction of the developer transport member,
A deforming portion for deforming the developer conveying member into a bent state by contacting a free end side of the rotating developer conveying member;
Restoring the developer transport member deformed to be in a deformed state without contacting the developer transport member and being deformed at the deformed portion, and having the opening,
An abutting portion that abuts a part of the developer conveying member that moves the restoring portion;
Is formed,
When the developer conveying member rotates and comes out of the deforming portion and moves to the restoring portion, the developer carried between the deformed developer conveying member and the deforming portion is removed from the developing portion. It is possible to fly to the opening with the restoration of the agent conveying member, and
The contact portion is located below the opening portion, and the developer transport member is in contact with the contact portion, and the contact portion serves as a fulcrum of the developer transport member . The region from the contacted portion that contacts the contact portion to the free end can be deformed downstream in the rotational direction.

  According to the present invention, in a developing device in which a developer storage chamber is arranged below a developer carrying member, a sufficient amount of developer is supplied to the developer carrying member to suppress the occurrence of image defects and to reduce the size. It is possible to provide a developing device capable of achieving the above and a process cartridge including the developing device.

1 is a schematic cross-sectional view of an image forming apparatus according to a first embodiment. 1 is a schematic cross-sectional view of a process cartridge according to a first embodiment. 1 is a schematic cross-sectional view of a process cartridge according to a first embodiment. 1 is a schematic cross-sectional view of a developing device according to a first embodiment. 1 is a schematic cross-sectional view of a developing device according to a first embodiment. 1 is a schematic cross-sectional view of a developing device according to a first embodiment. FIG. 6 is a schematic cross-sectional view of a developing device according to a second embodiment. FIG. 10 is a schematic cross-sectional view of a developing device according to a third embodiment. FIG. 10 is a schematic cross-sectional view of a developing device according to a third embodiment. 1 is a schematic cross-sectional view of a developing device according to a first embodiment. FIG. 3 is a schematic cross-sectional view of a developing device used in a comparative example.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be exemplarily described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. Absent.

[First embodiment]
With reference to FIGS. 1 to 6, a developing device according to a first embodiment of the present invention and a process cartridge including the developing device will be described.

(Description of image forming apparatus)
First, a developing device according to the present embodiment and an image forming apparatus to which a process cartridge including the developing device can be applied will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view of an image forming apparatus 100 in the present embodiment.

The image forming apparatus 100 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 the sheet material S (for example, recording paper, plastic sheet, cloth, etc.) based on the 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.

  The image forming apparatus 100 includes, as a plurality of image forming units, first, second, and third images for forming yellow (Y), magenta (M), cyan (C), and black (K) images, respectively. And fourth 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 line in a direction that intersects the vertical direction.

  In the present embodiment, the configurations and operations of the first to fourth image forming units are substantially the same except that the colors of 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 explain.

  In the present embodiment, the image forming apparatus 100 includes four drum-type photosensitive drums 1 (electrophotographic photosensitive members) arranged in parallel in a direction intersecting the vertical direction as a plurality of image carriers. . The photosensitive drum 1 is rotationally driven by a driving means (drive source) (not shown) in an arrow A direction (clockwise direction).

Around the photosensitive drum 1, a charging roller 2 as a charging member that uniformly charges the surface of the photosensitive drum 1, a laser beam L is emitted based on image information, and an electrostatic latent image is formed on the photosensitive drum 1. A scanner unit 3 is disposed as an exposure apparatus for forming the. Further, a developing unit 4 as a developing device that develops an electrostatic latent image as a toner image (developer image), and a cleaning unit that removes toner (transfer residual toner) remaining on the surface of the photosensitive drum 1 after transfer. A cleaning member 6 is disposed. Further, an intermediate transfer belt 5 for transferring the toner image on the photosensitive drum 1 to the sheet material S is disposed facing the four photosensitive drums 1.

  In this embodiment, a nonmagnetic one-component developer is used as the toner (developer). This toner is charged to the same polarity as the charging polarity of the photosensitive drum 1 (negative polarity in the present embodiment), and a portion exposed on the photosensitive drum 1 from the developing unit 4 described later (a portion where the charge has attenuated). By supplying this toner to the electrostatic latent image, the electrostatic latent image is developed as a toner image.

  In the present embodiment, the photosensitive drum 1, the charging roller 2, the developing unit 4, and the cleaning member 6 are integrally stored as a process cartridge 7. Further, the process cartridge 7 is configured to be attachable to and detachable from the image forming apparatus 100 via mounting means such as a mounting guide (not shown) and a positioning member provided in the image forming apparatus main body. In the present embodiment, the process cartridges 7 for each color all have the same shape, and each of the process cartridges 7 for each color has yellow (Y), magenta (M), cyan (C), black ( K) toner of each color is stored.

  In addition to this configuration, for example, a process cartridge in which the photosensitive drum 1 and the developing unit 4 are integrated may be used. That is, what is integrated as the process cartridge 7 is not limited to the above combination.

  An intermediate transfer belt 5 (intermediate transfer member) formed of an endless belt contacts all the photosensitive drums 1 provided for each color, and circulates (rotates) in the direction of arrow B (counterclockwise) in the figure. To do. 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 that support the rotation thereof.

  Further, four primary transfer rollers 8 as primary transfer members are arranged in parallel on the inner peripheral surface side of the intermediate transfer belt 5 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 come into contact. 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 supply (high voltage power supply) (not shown). As a result, the toner image on the photosensitive drum 1 is transferred (primary transfer) onto the intermediate transfer belt 5.

  Further, a secondary transfer roller 9 as a secondary transfer member 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 come into contact. 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) (not shown). As a result, the toner image on the intermediate transfer belt 5 is transferred (secondary transfer) to the sheet material S. The primary transfer roller 8 and the secondary transfer roller 9 have the same configuration.

  When forming an image on the sheet material S, first, the surface of the photosensitive drum 1 is uniformly charged by the charging roller 2. The charged surface of the photosensitive drum 1 is irradiated with laser light corresponding to the image information from the scanner unit 3, and an electrostatic latent image based on the image information is formed on the photosensitive drum 1. Thereafter, the electrostatic latent image formed on the photosensitive drum 1 is supplied with toner from the developing unit 4 and developed as a toner image. 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 a full-color image is formed, the above-described process is performed by the first to fourth image forming units SY,
Sequentially in SM, SC, and SK, the toner images of the respective colors are superimposed one after another on the intermediate transfer belt 5 to be primarily transferred. Thereafter, the sheet material S is conveyed to the secondary transfer portion N2 in synchronization with the movement of the intermediate transfer belt 5, and the four-color toner images on the intermediate transfer belt 5 are batched by the action of the secondary transfer roller 9. Then, it is secondarily transferred onto the sheet material S.

  The sheet material S to which the toner image is transferred is conveyed to the fixing device 10, and heat and pressure are applied to the sheet material S in the fixing device 10, whereby the toner image is fixed to the sheet material S. 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. Further, the secondary transfer residual toner remaining on the intermediate transfer belt 5 after the secondary transfer process is collected 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 a plurality (not all) of image forming units.

(Description of process cartridge)
The process cartridge 7 according to the present embodiment will be described with reference to FIG. FIG. 2 is a schematic cross-sectional view of the process cartridge 7 according to the present embodiment when viewed from the longitudinal direction (rotation axis direction) of the photosensitive drum 1. In the following description, terms used to describe the configuration and operation of the developing unit 4 such as “up”, “down”, “vertical”, and “horizontal” are used for image formation unless otherwise specified. The direction in the normal installation state (or use state) of the device shall be indicated. That is, for example, “upward” means “upward” in the state shown in FIGS. 2 and 3. 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 stored toner.

  The process cartridge 7 includes a photosensitive unit 13 including the photosensitive drum 1 and the like, and a developing unit 4 (developing apparatus) including a developing roller 17 and the like.

  The photoconductor unit 13 includes 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). A driving force is transmitted to the photosensitive drum 1 from a driving motor (not shown) as a driving means (driving source), and is rotated in the direction indicated by an arrow A (clockwise) in accordance with an image forming operation. As the photosensitive drum 1 that is the center of the image forming process, an organic photosensitive drum 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 transport layer in this order. . In the present embodiment, the rotational speed of the photosensitive drum 1 is set to 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 and is stored in the cleaning frame 14. The charging roller 2 as a charging member is driven to rotate by bringing a roller portion of conductive rubber into pressure contact with the photosensitive drum 1. Here, a DC voltage of −1100 V is applied to the core of the charging roller 2 with respect to the photosensitive drum 1, whereby a uniform dark portion potential (approximately −550 V) is applied to the surface of the photosensitive drum 1. Vd) is formed.

  Laser light is emitted from the scanner unit 3 to the photosensitive drum 1 having a uniform dark potential (Vd) formed on the surface in this way. As a result, the portion exposed on the surface of the photosensitive drum 1 loses its charge due to carriers from the carrier generation layer, and the potential decreases. As a result, the exposed portion has a bright portion potential Vl = −100 V, and the unexposed portion has a dark portion potential Vd = −550 V, so that an electrostatic latent image is formed on the surface of the photosensitive drum 1.

On the other hand, the developing unit 4 has a developing frame 18 as a frame that supports various elements in the developing unit 4. The developing unit 4 is provided with a developing roller 17 as a developer carrying member that contacts the photosensitive drum 1 and rotates in the direction indicated by an arrow D (counterclockwise). In the present embodiment, the developing roller 17 and the photosensitive drum 1 are moved in the same direction (in the present embodiment, from the bottom to the top in the figure) at the opposing portion (contact portion). So that each is rotating.

  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). The development side plates 19 (19R, 19L) are respectively attached to both sides of the development frame 18. In the present embodiment, the developing roller 17 is disposed in contact with the photosensitive drum 1. However, the developing roller 17 is disposed close to the photosensitive drum 1 at a predetermined interval. May be.

  Further, in the present embodiment, when a DC bias = −350 V is applied to the developing roller 17, the negatively charged toner is transferred only to the bright portion potential portion in the developing portion that contacts the photosensitive drum 1. The electrostatic latent image is visualized as a toner image. That is, it is a so-called reversal development system that transfers toner to an exposed portion.

  The developing roller 17 is a roller member having an elastic layer on the core metal. In this embodiment, a first layer (base layer) made of solid rubber in which carbon is dispersed in silicone rubber is formed on a stainless steel core bar having a 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 the rotation speed of the photosensitive drum 1.

The developing unit 4 is provided with a toner supply roller 20 as a developer supply member that rotates in the direction of arrow E (counterclockwise) in the figure so as to come into contact with the circumferential surface of the developing roller 17. In the present embodiment, the toner supply roller 20 and the developing roller 17 are rotated so that the surfaces of the toner supply roller 20 and the developing roller 17 move in opposite directions at the opposing portion (contact portion). The toner 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. Further, the developer unit 4 regulates the layer thickness of the toner supplied onto the developing roller 17 by the toner supply roller 20 so as to come into contact with the peripheral surface of the developing roller 17, and the developer regulation that applies charge. A developing blade 21 is disposed as a member.

  The toner supply roller 20 is a roller member in which an open-cell foam (hereinafter referred to as a foam layer) is formed on the outer periphery of a conductive metal core. The foam layer of the toner supply roller 20 has two functions of supplying the toner to the developing roller 17 and stripping off the toner that has not contributed to the development. The toner is peeled off by rubbing the edge portion of the foam cell on the developing roller 17 and the toner supply roller 20.

In the present embodiment, the toner supply roller 20 is an elastic material having an outer diameter of φ16 mm in which a polyurethane foam having a foamed skeleton structure and a relatively low hardness is formed on a core metal having an outer diameter of φ5 mm (cell diameter: 300 to 450 μm). A sponge roller was used. By constituting the toner supply roller 20 with a continuous foaming foam, it abuts against the developing roller 17 without applying excessive pressure, and at the time of toner supply and development onto the developing roller 17 with moderate irregularities on the surface of the foam. It is possible to remove the residual toner without being consumed. The scraping property of this cell structure is not limited to urethane foam, and other materials such as NBR rubber (NBR: nitrile rubber), silicone rubber, acrylic rubber, hydrin rubber, ethylene propylene rubber (EPDM) ), Commonly used rubbers such as chloroprene rubber, styrene butadiene rubber, isoprene rubber, acrylonitrile butadiene rubber, and composite mixtures thereof. In addition, a known ionic conductive agent, inorganic fine particles, carbon black, or the like can be dispersed as appropriate for adjusting the resistance of the foam layer.

  In order to assist the toner supply to the developing roller 17, a bias from the toner supply roller 20 side toward the developing roller 17 side may be applied to the toner supply roller 20. Thus, by applying a bias for biasing the negatively charged toner to the developing roller 17 side, it is possible to increase the amount of toner carried on the developing roller 17 in a state before rubbing against the developing blade 21. Become. Furthermore, by applying a bias, the toner density on the developing roller 17 is easily increased, and even when the surface roughness of the developing roller 17 is low, a uniform toner density is easily obtained.

  In the present embodiment, the toner supply roller 20 rotates in the opposite direction at the portion in contact with the developing roller 17 (so-called counter rotation), and the surface rotation speed is set to 0. 0 of the surface rotation speed of the developing roller 17. It was set to 85 times.

  The developing blade 21 is made of a thin metal plate and forms contact pressure by utilizing the spring elasticity of the thin plate, and the surface of the thin metal plate is in contact with the surface of 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. In the present embodiment, a phosphor bronze thin plate having a thickness of 0.1 mm is used. By rubbing between the developing blade 21 and the developing roller 17, the toner is triboelectrically charged and charged, and at the same time, the layer thickness is regulated. The developing blade 21 is supplied with a predetermined voltage (−550 V) from a blade bias power supply (not shown).

  A toner storage chamber 18a as a developer storage chamber formed in the developing frame 18 stores non-magnetic one-component toner. A toner conveying member 22 that is rotatably supported by the developing device frame 18 is provided in the toner storage chamber 18a. As will be described later, the toner conveying member 22 agitates the toner accommodated in the toner accommodating chamber 18a and conveys the toner to the developing chamber 18b in which the developing roller 17 and the toner supply roller 20 are provided. Note that the configuration according to the present embodiment can be applied to a developing device that includes only the toner storage chamber 18a and the toner conveying member 22 and includes a developer container (toner cartridge) that can be attached to and detached from the image forming apparatus main body.

  In this embodiment, the developing unit 4 is used in which the lifetime with respect to the toner capacity is set to be equivalent to 10,000 sheets in terms of 5% A4 paper printing rate. The developing unit 4 can swing on the photosensitive unit 13 around a coupling shaft 23 (23R, 23L) that fits into a hole 19a (19Ra, 19La) provided in the developing side plate 19 (19R, 19L). Is bound to. At the time of image formation, the developing unit 4 is urged by a developing unit pressure spring 24 as urging means, and rotates in the direction indicated by the arrow F (clockwise) about the coupling shaft 23. As a result, the developing roller 17 can be brought into contact with the photosensitive drum 1.

(Description of developing device)
With reference to FIGS. 3 to 6, the configuration of the developing unit 4 (developing device) according to the present embodiment and the process of supplying toner to the toner supply roller 20 in the developing unit 4 will be described. FIG. 3 is a schematic cross-sectional view of the process cartridge 7, and FIGS. 4 to 6 are schematic cross-sectional views of the developing unit 4, showing a state where toner is stored.

The developing unit 4 is provided with a toner conveying member 22 configured to be rotatable. 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 (rotation axis direction). The toner conveying member 22 is rotationally driven in a direction indicated by an arrow G (clockwise) by a driving unit (drive source) (not shown).

  The toner conveying member 22 includes a sheet portion 22a (developer conveying member) having elasticity for conveying toner, and a conveying support shaft (support shaft) 22b to which the sheet portion 22a is attached and which receives a rotational driving force. Yes. The conveyance support shaft 22b is disposed over the entire region in the longitudinal direction of the toner storage chamber 18a substantially parallel to the longitudinal direction (rotational axis direction) of the photosensitive drum 1, the developing roller 17, and the toner supply roller 20. The sheet portion 22a is a continuous sheet-like member (plate-like member) that extends over substantially the entire region in the longitudinal direction (rotation axis direction) of the conveyance support shaft 22b. And the sheet | seat part 22a is attached to the conveyance support shaft 22b in the one end part of the direction (rotational radius direction, short direction) substantially orthogonal to the longitudinal direction of the conveyance support shaft 22b, and the other end is a free end. In addition, the sheet | seat part 22a can be suitably produced using the resin-made sheets which have flexibility, 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.

  Next, the configuration of the toner storage chamber 18a will be described. The inner wall of the toner storage chamber 18a is brought into contact with the sheet portion 22a of the toner conveying member 22, and the deformed portion 18a2 that deforms the sheet portion 22a into a bent state and the deformed state in the deformed portion 18a2 of the sheet portion 22a are released. And a restoring portion 18a4 that restores the shape before deformation. A point p that is a boundary between the deforming portion 18a2 and the restoring portion 18a4 is defined as a boundary portion 18a3. That is, the toner storage chamber 18a includes a deforming portion 18a2, a boundary portion 18a3, and a restoring portion 18a4 in order from the upstream side in the rotation direction of the toner conveying member 22.

  Further, a partition wall 26 (which constitutes the inner wall of the toner storage chamber 18a) is provided between the developing chamber 18b and the toner storage chamber 18a, and a part of the partition wall 26 (above the toner storage chamber 18a) has toner. An opening 18c through which the water passes is formed. Further, the partition wall 26 has an abutting portion 26a that abuts on the sheet portion 22a. The contact part 26a is located below the opening 18c. In addition, the rotation of the toner conveying member 22 is more tangential than the tangent 29 on the downstream side in the rotation direction among the tangent lines that contact the rotation locus 28 of the conveyance support shaft 22b and pass through the lower end 18c1 (end on the downstream side in the rotation direction) of the opening 18c. It is set to be located (projected) on the upstream side in the direction.

  Therefore, when the sheet portion 22a restored from the deformed state to the natural state (original shape) in the restoring portion 18a4 further rotates from the restoring portion 18a4, the sheet portion 22a first comes into contact with the contact portion 26a (opening portion). 18c does not contact the lower end 18c1). As described above, the sheet portion 22a is in a natural state from the end of the boundary portion 18a3 until it contacts the contact portion 26a. That is, the restoration portion 18a4 is in contact with the contact portion from the boundary portion 18a3 of the toner storage chamber 18a. The area up to 26a is indicated. And the opening part 18c is arrange | positioned in the decompression | restoration part 18a4. The restoring portion 18a4 is disposed above the horizontal plane including the rotation axis of the toner conveying member 22. In other words, the boundary portion 18a3 is provided at the same height as the horizontal plane passing through the rotation center of the toner conveying member 22 or above the horizontal plane. Further, since the opening 18c is provided above the toner storage chamber 18a, the toner conveyance from the toner storage chamber 18a to the developing chamber 18b is performed against gravity.

  Hereinafter, a dimensional relationship between the toner storage chamber 18a and the toner transport member 22 will be described, and a process in which toner is transported to the developing chamber 18b as the toner transport member 22 rotates will be described.

First, the distance from the rotation center of the toner conveying member 22 to each part is defined as follows.
L1: A distance from the rotation center of the toner conveying member 22 to the free end of the sheet portion 22a.
(L1 corresponds to the maximum value of the rotation radius of the toner conveying member 22 in a natural state where the sheet portion 22a is not deformed.)
L2: The maximum value of the linear distance from the rotation center of the toner conveying member 22 to the inner wall 18a1 of the toner storage chamber 18a that is in contact with the sheet portion 22a.
L3: A linear distance from the rotation center of the toner conveying member 22 to the lower end 18c1 of the opening 18c (that is, the lowest point of the opening 18c).
L4: A linear distance from the rotation center of the toner conveying member 22 to the deforming portion 18a2.
L5: A linear distance from the rotation center of the toner conveying member 22 to the contact portion 26a.

In the present embodiment, the distances L1, L2, L3, L4, and L5 satisfy the following relationship.
L1> L2 (1)
L2> L4 (2)
L1> L3 (3)
L1> L5 (4)
Hereinafter, effects obtained by satisfying the relationships (1) to (4) will be described.

  Due to the relationship (1), the sheet portion 22a comes into contact with the inner wall 18a1 of the toner storage chamber 18a below the toner storage chamber 18a. The sheet portion 22a abuts on the inner wall 18a1 of the toner storage chamber 18a, and advances rotation while being deformed by the elasticity of the sheet portion 22a, whereby the toner in the toner storage chamber 18a can be conveyed. Similarly, in the deformable portion 18a2, the sheet portion 22a abuts against the inner wall of the deformable portion 18a2, and proceeds to rotate in a deformed state (a bent and curved state) due to the elasticity of the sheet portion 22a. The inner wall 18a1 can be regarded as a “deformation part”.

  Due to the relationship (2), the deformation amount of the sheet portion 22a in the deformation portion 18a2 becomes larger. Accordingly, it is possible to more reliably form the wedge-shaped region 27a (hereinafter referred to as the wedge-shaped portion 27a) defined by the sheet portion 22a that is bent in contact with the deformable portion 18a2 and the deformable portion 18a2. it can. By placing the toner accumulated in the wedge-shaped portion 27a on the surface of the sheet portion 22a, the toner can be conveyed against the direction of gravity.

  When the toner conveying member 22 further rotates from the deforming portion 18a2, the free end of the sheet portion 22a passes through the boundary portion 18a3 and reaches the restoring portion 18a4. As shown in FIG. 4, 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 state of being deformed by the deforming portion 18a2. It is restored to its natural state (original shape) by elastic restoring force. As described above, as the sheet portion 22a is restored, the toner carried and transported on the toner transport member 22 can fly toward the opening 18c. That is, according to the relationship (3), the toner can be more reliably conveyed to the opening 18c against gravity.

  Since the opening 18c is provided above the boundary 18a3, the toner flies in the direction opposite to the direction of gravity. As a result, there is toner that passes over the lower end 18c1 of the opening 18c and is transported to the developing chamber 18b, and there is toner that cannot exceed the lower end 18c1 of the opening 18c due to the influence of gravity.

  When the toner conveying member 22 further rotates from the restoring portion 18a4, a part of the sheet portion 22a comes into contact with the contact portion 26a. This is because the contact portion 26a is positioned below the opening portion 18c, contacts the rotation locus 28 of the conveyance support shaft 22b, and passes through the lower end 18c1 of the opening portion 18c. This is because it is set so as to be positioned upstream of the rotational direction.

  Due to the relationship (4), the sheet portion 22a comes into contact with the contact portion 26a at a part of the rotation center side from the free end. As shown in FIG. 5, when a part of the rotation center side of the free end of the seat portion 22a and the contact portion 26a contact each other, a wedge-shaped portion is formed from the contact portion 26a to the free end side of the seat portion 22a. Is done. In this wedge-shaped portion, a part of the toner that could not be passed over the lower end 18c1 of the opening 18c is accumulated, and further drop is suppressed. Further, as shown in FIG. 6, when the toner conveying member 22 abuts against the abutting portion 26a, the free end side of the sheet portion 22a from the abutting portion 26a moves downstream in the rotational direction with the abutting portion 26a as a fulcrum. Therefore, the toner accumulated in the wedge-shaped portion is pushed into the opening 18c. In the present embodiment, it is set so that a wedge-shaped portion is formed on the free end side of the sheet portion 22a from the contact portion 26a even when there is no toner.

  In the present embodiment, the contact portion 26a is set between a vertical line passing through the rotation center of the toner conveying member 22 and a vertical line passing through the boundary portion 18a3. Similarly, the lower end 18c1 of the opening 18c is set between a vertical line passing through the rotation center of the toner conveying member 22 and a vertical line passing through the boundary 18a3.

(Effects of developing device and process cartridge according to this embodiment)
The effects of the developing unit 4 (developing device) described above and the process cartridge 7 including the developing unit 4 will be described.

  Effect (1)... The toner conveying member 22 that has been deformed in the deforming portion 18a2 restores its shape in the restoring portion 18a4. It is possible to fly to 18c. As a result, the flying toner passes over the lower end of the opening 18 c and is conveyed to the developing chamber 18 b, and a part of the toner is also conveyed above the toner supply roller 20. Therefore, since the toner is supplied to the toner supply roller 20 not only below but also above the toner supply roller 20, high-quality image formation with little change in solid density can be performed. That is, since toner can be supplied from above the toner supply roller 20, it is possible to solve the occurrence of image density tracking failure, which has been cited as a problem of the configuration disclosed in Patent Document 1 (prior art).

  Effect (2): A part of the rotation center side of the free end of the toner conveying member 22 and the abutting portion 26a abut, so that the wedge-shaped portion extends from the abutting portion 26a to the free end of the toner conveying member 22. It is formed. In this wedge-shaped portion, a part of the toner that could not pass the lower end of the opening 18c is accumulated, and further drop is suppressed (FIG. 10). Further, when the toner conveying member 22 abuts on the abutting portion 26a, the free end side of the toner conveying member 22 from the abutting portion 26a is deformed to the downstream side in the rotation direction with the abutting portion 26a serving as a fulcrum. The toner accumulated in the portion is pushed into the opening 18c. For this reason, the toner that could not exceed the lower end of the opening 18c due to the influence of gravity can be partially transported to the developing chamber 18b, so that the toner can be transported efficiently. it can.

  Effect (3)... The toner conveying member 22 has a simple configuration comprising an elastic sheet portion 22a and a conveying support shaft 22b that rotatably supports the sheet portion 22a. Therefore, the toner conveying member 22 itself 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 of the toner storage chamber 18a. Therefore, the toner storage chamber 18a can be downsized. That is, the problem regarding downsizing, which has been cited as the problem of the configuration disclosed in Patent Document 1 (prior art), can be solved.

Effect (4): The abutting portion 26a is in contact with the rotation locus 28 of the conveying support shaft 22b and out of the tangent 29 passing through the lower end 18c1 of the opening 18c in the rotational direction downstream side, the toner conveying member 22. Is located upstream in the direction of rotation. Therefore, the wedge-shaped portion can be more reliably formed on the free end side of the seat portion 22a from the contact portion 26a.

  Effect (5): The abutting portion 26 a is provided between a vertical line passing through the boundary portion 18 a 3 and a vertical line passing through the rotation center of the toner conveying member 22. Therefore, the toner can be stored in a wedge-shaped portion formed from the contact portion 26a to the free end side of the toner conveying member 22 before the flying toner falls due to the influence of gravity. Thereby, the toner can be more efficiently conveyed to the developing chamber 18b. However, even when the position of the contact portion 26a is not defined in this way, it is possible to solve the problems of downsizing and occurrence of image density tracking failure described above.

  Effect (6): The lower end 18 c 1 of the opening 18 c is provided between a vertical line passing through the boundary 18 a 3 and a vertical line passing through the rotation center of the toner conveying member 22. Therefore, before the flying toner falls due to the influence of gravity, the toner can pass over the lower end 18c1 of the opening 18c, and the toner can be more efficiently conveyed to the developing chamber 18b. However, even when the position of the lower end 18c1 of the opening 18c is not defined in this way, it is possible to solve the problems of downsizing and occurrence of poor image density tracking described above.

[Second Embodiment]
FIG. 7 shows a schematic cross-sectional view of a developing device according to the second embodiment of the present invention. In the developing unit according to the present embodiment, both the contact portion 26 a and the lower end 18 c 1 of the opening 18 c are set downstream of the toner conveyance member 22 in the rotation direction with respect to the vertical line passing through the rotation center of the toner conveyance member 22. ing. This is different from the configuration of the first embodiment (the contact portion 26a and the lower end 18c1 of the opening 18c are set on the upstream side in the rotation direction of the toner conveying member 22). However, the other configuration is the same as that of the first embodiment, and thus the description thereof is omitted. The operational effects of the present embodiment will be described in the following [Evaluation results of the first and second embodiments and the comparative example].

[Evaluation results of the first and second embodiments and the comparative example]
In order to more easily explain the effects of the developing devices according to the first and second embodiments described above and the process cartridges including the developing devices, the effects were compared and verified using comparative examples.

  Here, as a comparative example, the developing device shown in FIG. 11 was used. The configuration of the developing frame 180 according to the comparative example shown in FIG. 11 is basically the same as the configuration of the developing frame 18 of the first and second embodiments, but does not have the contact portion 26a. Different from the first and second embodiments. That is, in this comparative example, the restoration unit 180a4 indicates the region from the boundary 180a3 to the opening 180c of the toner storage chamber 180a. For this reason, when the sheet part 220a restored from the deformed state to the natural state (original shape) in the restoration part 180a4 further rotates from the restoration part 180a4, the sheet part 220a hits the periphery of the opening part 180c.

The evaluation methods of the first and second embodiments and the comparative example are as follows. For image evaluation, three solid black images are output continuously, and the evaluation is based on the density difference between the leading and trailing edges of the third solid black image.
This was carried out using a spectrodensitometer 500 made by te. The print test and evaluation image are output in a single color. The density follow-up evaluation was carried out after leaving the image forming apparatus in an evaluation environment of 25.0 ° C. and 50% Rh for one day to adjust to the environment, after printing 100 sheets, and after printing 9000 sheets. . The printing test was performed by continuously passing a horizontal line of recorded images having an image ratio of 5%. The symbols ◯, Δ, and x used for evaluation indicate the following states.
◯: The density difference between the leading edge and the trailing edge of the paper in a solid black image is less than 0.2. Δ: The density difference between the leading edge of the paper and the trailing edge in the solid black image is 0.2 or more and less than 0.3. In solid black images, the density difference between the leading edge and the trailing edge of the paper is 0.3 or more.

Table 1 shows the evaluation results.

[Superiority over comparative example]
Based on the evaluation result, the superiority of the first and second embodiments over the comparative example will be described.

  First, in the density follow-up evaluation, the first embodiment was good with no image defect throughout durability. On the other hand, in the second embodiment, in the second half of the endurance (after printing 9,000 sheets) when the remaining amount of toner was low, a slight image defect occurred within the allowable range, and the remaining amount of toner was reduced in the comparative example. An image defect occurred in the second half of the durability. The reason for this will be described below.

  In the first embodiment, the sheet portion 22a is released from the deformed state in the deformable portion 18a2, and is restored to its natural state (original shape) by its own elastic restoring force, whereby the toner is removed. It can fly toward the opening 18c. Since the opening 18c is provided above the boundary 18a3, the toner flies against the direction of gravity. However, not all of the toner exceeds the lower end of the opening 18c, and depending on the case, there is toner that cannot exceed the lower end 18c1 of the opening 18c due to the influence of gravity.

  Here, when the toner conveying member 22 further rotates from the restoring portion 18a4, the sheet portion 22a of the toner conveying member 22 comes into contact with the contact portion 26a at a part of the rotation center side from the free end. When a portion of the seat portion 22a closer to the rotation center than the free end contacts the abutting portion 26a, a wedge-shaped portion is formed from the abutting portion 26a to the free end side of the seat portion 22a. In this wedge-shaped portion, a part of the toner that could not be passed over the lower end 18c1 of the opening 18c is accumulated, and further drop is suppressed. Furthermore, since the seat portion 22a abuts against the abutment portion 26a, the free end side of the seat portion 22a is deformed from the abutment portion 26a to the downstream side in the rotational direction with the abutment portion 26a as a fulcrum. The toner accumulated in the toner is pushed into the opening 18c. For this reason, it is possible to partially convey the toner that could not exceed the lower end 18c1 of the opening 18c to the developing chamber 18b due to the influence of gravity.

  In the first embodiment, the contact portion 26a is set between a vertical line passing through the rotation center of the toner conveying member 22 and a vertical line passing through the boundary portion 18a3. Therefore, before the toner falls due to the influence of gravity, the toner can be stored in a wedge-shaped portion formed from the contact portion 26a to the free end side of the sheet portion 22a, and the toner can be efficiently transferred to the developing chamber 18b. Can be transported. Further, the lower end 18c1 of the opening 18c is similarly set between a vertical line passing through the rotation center of the toner conveying member 22 and a vertical line passing through the boundary 18a3. Therefore, before the flying toner falls due to the influence of gravity, the toner can pass over the lower end 18c1 of the opening 18c, and similarly, the toner can be efficiently conveyed to the developing chamber 18b. That is, in the first embodiment, even when the remaining amount of toner in the latter half of the endurance is low, the toner can be efficiently conveyed to the developing chamber 18b, and solid color follow-up can be ensured. .

On the other hand, in the comparative example, the sheet portion 220a is restored from the deformed state in the deformable portion 180a2.
This is similar to the first and second embodiments in that the toner is caused to fly by being restored to the natural state at 80a4. However, there is no portion corresponding to the contact portion 26a, and the restoration portion 180a4 is a region from the boundary portion 180a3 to the opening portion 180c of the toner storage chamber 180a. Therefore, when the sheet part 220a restored from the deformed state to the natural state (original shape) in the restoration part 180a4 further rotates from the restoration part 180a4, the sheet part 220a hits the periphery of the opening part 180c. That is, in the configuration of the comparative example, the wedge-shaped portion formed from the contact portion 26a to the free end side of the seat portion 22a as described above is not formed. For this reason, the toner that has not exceeded the lower end 180c1 of the opening 180c due to the effect of gravity falls into the toner storage chamber 180a as it is. As a result, in the state where the remaining amount of toner in the second half of the endurance is low, toner conveyance to the developing chamber 180b becomes insufficient, and the solid image density cannot be maintained.

  Further, the second embodiment includes the contact portion 26a as in the first embodiment, but the contact portion 26a is more than the vertical line passing through the rotation center of the toner conveying member 22. It is set on the downstream side in the rotation direction of the toner conveying member 22. Therefore, from the point when the sheet portion 22a passes through the boundary portion 18a3, is released from the deformed state in the deformable portion 18a2, and the toner is caused to fly toward the opening portion 18c, the toner conveying member 22 rotates and the sheet portion 22a is hit. The time until it comes into contact with the contact portion 26a becomes longer. For this reason, the ratio of toner falling due to the influence of gravity is slightly increased as compared with the first embodiment.

  However, when the sheet portion 22a comes into contact with the contact portion 26a and a wedge-shaped portion is formed from the contact portion 26a to the free end side of the sheet portion 22a, toner accumulates in the wedge-shaped portion and further drops. Can be suppressed. Further, since the toner conveying member 22 abuts on the abutting portion 26a, the free end side of the sheet portion 22a is deformed from the abutting portion 26a to the downstream side in the rotation direction with the abutting portion 26a as a fulcrum, so that the wedge shape The toner accumulated in the portion is pushed into the opening 18c. For this reason, as in the first embodiment, it is possible to partially convey the toner to the developing chamber 18b even for the toner that could not exceed the lower end 18c1 of the opening 18c due to the influence of gravity. It becomes.

  According to the above evaluation results, it can be seen that an image defect has occurred although it is slight in the state where the remaining amount of toner in the second half of the endurance is small. That is, as compared with the first embodiment, the second embodiment means that toner conveyance to the developing chamber 18b is reduced in the second half of the endurance. However, this minor image defect is within an allowable range, and sufficiently good image quality can be obtained as compared with the conventional technique and the comparative example.

  As described above, according to the first and second embodiments, a sufficient amount of developer is supplied to the developer carrier in the developing device in which the developer storage chamber is disposed below the developer carrier. It is possible to provide a developing device capable of suppressing the occurrence of image defects and reducing the size. It is also possible to provide a process cartridge including the same.

[Third embodiment]
The third embodiment of the present invention will be described with reference to FIGS. 8 and 9 are schematic sectional views of the developing device according to the present embodiment.

  In the present embodiment, the toner conveying member 22 has an auxiliary sheet portion 22c (developer auxiliary conveying member) in a phase downstream of the sheet portion 22a in the rotation direction of the conveying support shaft 22b in addition to the sheet portion 22a and the conveying support shaft 22b. ) Is a feature. Since the configuration other than this is the same as that of the first embodiment, the same portions are denoted by the same reference numerals and description thereof is omitted.

  The auxiliary sheet portion 22c is a continuous sheet (plate-like member) that extends over substantially the entire region in the longitudinal direction (rotation axis direction) of the transport support shaft 22b. The auxiliary sheet portion 22c is attached to the conveyance support shaft 22b at one end in a direction (rotational radius direction, short direction) substantially orthogonal to the longitudinal direction of the conveyance support shaft 22b, similarly to the sheet portion 22a. In the present embodiment, a 100 μm polyester film is used as the auxiliary sheet portion 22c, but it is not necessary to use a deformable material. In the present embodiment, the angle formed by the sheet portion 22a and the auxiliary sheet portion 22c is about 90 ° in the rotation direction with respect to the sheet portion 22a. However, the angle formed by the two is not limited to this, and any value that allows the toner to remain on the sheet portion 22a may be used.

(Comparison with the first embodiment)
In order to verify the effects of the developing device according to the present embodiment and the process cartridge including the developing device, a comparison with the first embodiment described above was performed. Here, density follow-up evaluation at the initial stage of image formation was performed.

In the density follow-up evaluation performed here, the image forming apparatus is left in an evaluation environment of 25.0 ° C. and 50% Rh for one day, and after accustomed to the environment, three solid black images are output continuously. The density difference between the output leading edge and the trailing edge of the third solid black image was evaluated. For this evaluation, s made by X-Rite
A vector densitometer 500 was used. Note that the print test and the evaluation image are output in a single color. Further, in this evaluation, the initial density followability is started by continuously passing a predetermined number of horizontal line recorded images having an image ratio of 5%, starting from a state before the toner is conveyed into the developing chamber 18b. Is evaluated. Specifically, two initial printing sheets (10 sheets and 30 sheets) are set, and comparison is made for each. The symbols ◯, Δ, and x used for evaluation indicate the following states.
◯: The density difference between the leading edge and the trailing edge of the paper in a solid black image is less than 0.2. Δ: The density difference between the leading edge of the paper and the trailing edge in the solid black image is 0.2 or more and less than 0.3. In solid black images, the density difference between the leading edge and the trailing edge of the paper is 0.3 or more.

Table 2 shows the evaluation results.

  In the density follow-up evaluation in the initial stage, the present embodiment can ensure the follow-up ability of the solid density even when the initial number of printed sheets is 10. Hereinafter, this factor will be described.

  As shown in FIG. 9, in the present embodiment, the toner conveying member 22 includes a sheet portion 22a, a conveying support shaft 22b, and an auxiliary sheet portion 22c. The seat portion 22a abuts against the inner wall at the deformable portion 18a2, and advances its rotation in a deformed state due to the elasticity of the seat portion 22a. Then, the toner accumulated in the wedge-shaped portion 27a defined by the bent sheet portion 22a and the deformable portion 18a2 is placed on the surface of the sheet portion 22a, and the toner is opposite to the direction of gravity. Can be transported.

Thereafter, the posture of the sheet portion 22 a approaches the vertical posture as the toner conveying member 22 rotates. At this time, the toner overflowing from the wedge-shaped portion 27a on the free end side of the sheet portion 22a tends to slide down in the direction of gravity from above the sheet portion 22a. However, in the present embodiment, the auxiliary sheet portion 2 in the phase downstream of the sheet portion 22a in the rotation direction of the conveyance support shaft 22b.
Since 2c is provided, the auxiliary sheet part 22c can receive the toner sliding down from the sheet part 22a. Therefore, even if the posture of the sheet portion 22a approaches a vertical posture, it is possible to suppress the toner from sliding off from the sheet portion 22a in the direction of gravity.

  Accordingly, even when the sheet portion 22a is deformed in the deformable portion 18a2, the amount of toner placed on the sheet portion 22a can be increased. As a result, the amount of toner transport from the toner storage chamber 18a to the developing chamber 18b in the initial stage can be increased, and the followability of the solid density can be ensured even when the initial number of printed sheets is 10.

  Here, it is known that the effect of the auxiliary sheet portion 22c is remarkable in a state where the remaining amount of toner is large. When toner is continuously present from the auxiliary sheet portion 22c onto the sheet portion 22a, the toner received by the auxiliary sheet portion 22c is less likely to slide off from the sheet portion 22a in the direction of gravity. Note that the toner flying toward the opening 18c when the sheet portion 22a is restored from the deformed state is in the vicinity of the wedge-shaped portion 27a. Therefore, when the remaining amount of toner is large and toner is continuously present from the auxiliary sheet portion 22c to the free end side of the sheet portion 22a, the amount of toner flying toward the opening portion 18c can be increased.

  Moreover, as shown in FIG. 10, the auxiliary sheet part 22c is not provided in the first embodiment. For this reason, the sheet portion 22a in a state of being bent in contact with the deformable portion 18a2 and the toner accumulated in the wedge-shaped portion 27a defined by the deformable portion 18a2 slide off in the gravitational direction from the sheet portion 22a. . Therefore, compared with the present embodiment, the amount of toner transport from the toner storage chamber 18a to the developing chamber 18b at the initial stage of image formation is small. As a result, when the initial number of printed sheets was 10, the image defect with respect to the solid density occurred although it was slight. However, when the initial number of printed sheets is 30, the followability of the solid density can be ensured.

  As described above, in the present embodiment, the auxiliary sheet portion 22c is attached to the conveyance support shaft 22b at a phase downstream of the sheet conveyance portion 22a in the rotation direction of the toner conveyance member 22. Therefore, even when the posture of the toner conveying member 22 approaches the vertical posture, the toner can be prevented from sliding off from the toner conveying member 22 in the gravity direction. As a result, the amount of toner on the toner conveying member 22 can be increased, and the toner can be efficiently conveyed to the developing chamber 18b. That is, in a developing device in which a developer storage chamber is disposed below the developer carrier, a sufficient amount of developer is supplied to the developer carrier to suppress the occurrence of image defects and to reduce the size. It is possible to provide a possible developing device and a process cartridge including the developing device.

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 4 Developing unit 7 Process cartridge 17 Developing roller 18a Toner storage chamber 18a1 Inner wall 18a2 Deformation part 18a3 Boundary part 18a4 Restoration part 18c Opening part 18c1 Opening lower end 20 Toner supply roller 22 Toner conveyance member 22a Sheet part 22b Conveyance support Shaft 26 Partition 26a Contact part

Claims (10)

A developing device used in an image forming apparatus,
A developer carrying member carrying the developer;
A developing chamber provided with the developer carrier;
A developer storage chamber that is disposed below the development chamber and stores a developer to be supplied to the development chamber when the development device is used in the image forming apparatus ;
In the developing device for supplying the developer from the developer accommodating chamber to the developing chamber through an opening formed above the developer accommodating chamber,
In the developer storage chamber,
One end side of the elastic sheet-like developer transport member is supported by a rotatable support shaft, and is provided to rotate in a direction from the lower side of the developer storage chamber toward the opening,
On the inner wall of the developer storage chamber,
In order from the bottom of the developer storage chamber along the rotation direction of the developer transport member,
A deforming portion for deforming the developer conveying member into a bent state by contacting a free end side of the rotating developer conveying member;
Restoring the developer transport member deformed to be in a deformed state without contacting the developer transport member and being deformed at the deformed portion, and having the opening,
An abutting portion that abuts a part of the developer conveying member that moves the restoring portion;
Is formed,
When the developer conveying member rotates and comes out of the deforming portion and moves to the restoring portion, the developer carried between the deformed developer conveying member and the deforming portion is removed from the developing portion. It is possible to fly to the opening with the restoration of the agent conveying member, and
The contact portion is located below the opening portion, and the developer transport member is in contact with the contact portion, and the contact portion serves as a fulcrum of the developer transport member . 2. A developing device according to claim 1, wherein a region extending from the contacted portion contacting the contact portion to the free end is deformable downstream in the rotation direction. The contact portion is
Than a tangent line that is in contact with the rotation trajectory of the support shaft and that is on the downstream side in the rotation direction among the tangent lines that pass through the end portion on the downstream side in the rotation direction of the developer conveying member at the end of the opening. The developing device according to claim 1, wherein the developing device is located upstream in the rotation direction. The contact portion is
A vertical line passing through the boundary between the deforming portion and the restoring portion;
The developing device according to claim 1, wherein the developing device is provided between a vertical line passing through a rotation center of the developer conveying member. The lower end of the opening is
A vertical line passing through the boundary between the deforming portion and the restoring portion;
The developing device according to claim 1, wherein the developing device is provided between a vertical line passing through a rotation center of the developer conveying member. The support shaft includes
5. The developing device according to claim 1, wherein a developer auxiliary transport member is provided downstream of the developer transport member in the rotation direction. 6. A process cartridge configured to be detachable from the image forming apparatus,
An electrophotographic photoreceptor;
A developer carrying member for carrying a developer for developing the electrostatic latent image formed on the electrophotographic photosensitive member;
A developing chamber provided with the developer carrier;
A developer storage chamber that is disposed below the developing chamber when the process cartridge is mounted on the image forming apparatus and stores the developer supplied to the developing chamber;
In the process cartridge configured to pass the opening formed above the developer storage chamber and supply the developer from the developer storage chamber to the development chamber,
In the developer storage chamber,
One end side of the elastic sheet-like developer transport member is supported by a rotatable support shaft, and is provided to rotate in a direction from the lower side of the developer storage chamber toward the opening,
On the inner wall of the developer storage chamber,
In order from the bottom of the developer storage chamber along the rotation direction of the developer transport member,
A deforming portion for deforming the developer conveying member into a bent state by contacting a free end side of the rotating developer conveying member;
Restoring the developer transport member deformed to be in a deformed state without contacting the developer transport member and being deformed at the deformed portion, and having the opening,
An abutting portion that abuts a part of the developer conveying member that moves the restoring portion;
Is formed,
When the developer conveying member rotates and comes out of the deforming portion and moves to the restoring portion, the developer carried between the deformed developer conveying member and the deforming portion is removed from the developing portion. It is possible to fly to the opening with the restoration of the agent conveying member, and
The contact portion is located below the opening portion, and the developer transport member is in contact with the contact portion, and the contact portion serves as a fulcrum of the developer transport member . 2. A process cartridge according to claim 1, wherein a region extending from the contacted portion that contacts the contact portion to the free end is deformable downstream in the rotational direction. The contact portion is
Than a tangent line that is in contact with the rotation trajectory of the support shaft and that is on the downstream side in the rotation direction among the tangent lines that pass through the end portion on the downstream side in the rotation direction of the developer conveying member at the end of the opening. The process cartridge according to claim 6, wherein the process cartridge is located upstream in the rotation direction. The contact portion is
A vertical line passing through the boundary between the deforming portion and the restoring portion;
8. The process cartridge according to claim 6, wherein the process cartridge is provided between a vertical line passing through a rotation center of the developer conveying member. The lower end of the opening is
A vertical line passing through the boundary between the deforming portion and the restoring portion;
9. The process cartridge according to claim 6, wherein the process cartridge is provided between a vertical line passing through a rotation center of the developer conveying member. The support shaft includes
10. The process cartridge according to claim 6, wherein a developer auxiliary transport member is provided downstream of the developer transport member in the rotation direction. 11.

Images