JP5534730B2 - Developer transport device, developing device, and process cartridge - Google Patents

Description

  The present invention relates to a developer transport device, a developing device, and a process cartridge that can be attached to and detached from an electrophotographic image forming apparatus.

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

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

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

  The developing device in the process cartridge described above generally includes a developer carrying body for supplying a developer to a photosensitive member, a developing chamber provided with a developer supplying body for supplying the developer to the developer carrying body, and the like. A developer storage chamber for storing the developer supplied to the development chamber; Patent Documents 1 and 2 disclose inventions relating to a developer conveying apparatus having such a developing chamber and a developer storage chamber.

  In the developer transport device described in Patent Document 1, a photosensitive member is disposed below an intermediate transfer member serving as a transfer member and a recording material carrier serving as a transfer member. Further, a developing chamber is disposed below the photoconductor, and a developer storage chamber is disposed below the developing chamber. Therefore, in order for the developer to be supplied from the developer storage chamber to the development chamber, the developer needs to be conveyed against gravity. In the image forming apparatus described in Patent Document 1, the transport member includes a transport support shaft, a stirring member supported by the transport support shaft, and a sheet portion having elasticity at the tip of the stirring member. . According to such a configuration, the developer can be lifted and supplied to the developing chamber while the sheet portion is in contact with the inner wall of the developer accommodating chamber.

  In the developer transport device described in Patent Document 2, a developing chamber is disposed below the photosensitive member, and a developer storage chamber is disposed on the left side of the developing chamber. In order for the developer stored in the lower half of the developer storage chamber to be supplied from the developer storage chamber to the development chamber by the transport member, the developer needs to be transported against gravity. In the image forming apparatus described in Patent Document 2, the conveyance member includes a conveyance support shaft, a stirring member supported by the conveyance support shaft, and a protrusion formed on a surface on the rotation direction side of the stirring member. It has become. According to such a configuration, the agitating member can pump up the developer on the tip side of the protrusion and stably supply the developer inside the developer storage chamber to the developing chamber in a necessary minimum amount.

JP 2003-173083 A JP-A-6-186852

  However, in the developer conveyance device described in Patent Document 1, when the developer is conveyed from the developer storage chamber to the development chamber, the developer is removed from the sheet member attached to the end portion in the rotational radius direction of the conveyance member. Easy to fall. Further, in the developer transport device described in Patent Document 2, when the developer is transported from the developer storage chamber to the development chamber, the developer is likely to fall from the tip side of the protrusion on the stirring member. Therefore, when the amount of the developer is small in the developer storage chamber, the supply amount of the developer supplied from the developer storage chamber to the development chamber may be reduced.

  SUMMARY OF THE INVENTION In view of the above circumstances, the present invention provides a developer transport device in which a developer is efficiently supplied from a developer storage chamber to an adjacent chamber regardless of the amount of developer inside the developer storage chamber. Is an issue.

In order to solve the above-described problems, a developer transport device of the present invention includes a developer container into which a developer is placed, and a transport member that is rotatably disposed inside the developer container and can transport the developer. The developer container includes: a developer storage chamber that stores the developer; and an adjacent chamber that is provided vertically below the developer storage chamber and that is adjacent to the developer storage chamber. An opening formed in a partition wall that divides the developer storage chamber and the adjacent chamber and passes therethrough, and the conveying member is disposed below the opening and is disposed inside the developer storage chamber. A rotatable rotation shaft, a plate-like portion having a base end portion fixed to the rotation shaft and extending in a plate shape and having elasticity, and a development surface formed on the surface in the rotation direction on the distal end side of the plate-like portion. A developer holding portion having a recess capable of holding the developer, and the recess and the front If the opening is located at a position facing and projecting the recess parallel to the moving direction, overlap at least in part with said opening, after the recess the conveying member rotates and holds the developer, When the plate-like portion abuts against the developer container contact portion provided on the partition wall, the concave portion is decelerated with the contact point between the plate-like portion and the developer container contact portion as a fulcrum to the opening. And the developer held in the recess receives the circumferential force due to inertial force and is discharged from the recess and is transported to the adjacent chamber through the opening. To do.

  As described above, according to the present invention, the conveying member has the concave portion that is formed on the surface in the rotational direction on the tip side of the plate-like portion and can hold the developer. Therefore, the concave portion scoops up the developer, and the developer is conveyed to the adjacent chamber through the opening. As a result, the developer is efficiently supplied from the developer storage chamber to the adjacent chamber regardless of the amount of the developer inside the developer storage chamber.

1 is a cross-sectional view illustrating configurations of a developer transport device, a developing unit, and an image forming apparatus according to Embodiment 1 of the present invention. FIG. 4 is a cross-sectional view of the process cartridge as viewed from the axial direction of the photosensitive drum. It is sectional drawing which shows the structure of a developing unit. It is sectional drawing which shows the structure of a developing unit. It is sectional drawing which shows the structure of the conveying member and opening part seen from the direction of the arrow V of FIG. 6 is a cross-sectional view illustrating a configuration of a developing unit according to Embodiment 2. FIG. It is sectional drawing which shows the structure of a developing unit. It is sectional drawing which shows the structure of the image development unit which concerns on a 1st comparative example. It is sectional drawing which shows the structure of the image development unit which concerns on a 1st comparative example. It is sectional drawing which shows the structure of the image development unit which concerns on a 2nd comparative example. It is sectional drawing which shows the structure of the image development unit which concerns on a 2nd comparative example. It is sectional drawing which shows the structure of the developing unit which concerns on a 3rd comparative example. It is sectional drawing which shows the structure of the developing unit which concerns on a 3rd comparative example. 6 is a cross-sectional view illustrating a configuration of a developing unit according to Embodiment 3. FIG. It is a top view etc. which show the modification of the sheet | seat part of a conveyance member. FIG. 6 is a cross-sectional view illustrating an example and a modification of a toner holding portion of a conveying member.

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

  FIG. 1 is a cross-sectional view illustrating configurations of a developer transport device 4a (described later), a developing unit 4, and an image forming apparatus 100 according to Embodiment 1 of the present invention. The overall configuration of the electrophotographic image forming apparatus, that is, the image forming apparatus 100 will be described below with reference to FIG. An image forming apparatus 100 in FIG. 1 is a full-color laser beam printer that employs an inline method and an intermediate transfer method. The image forming apparatus 100 can form a full-color image on a recording material (for example, recording paper, plastic sheet, cloth, etc.) according to the image information.

  The image forming apparatus 100 includes an image forming apparatus main body (hereinafter simply referred to as “apparatus main body”) 100A. The image information is transmitted from an image reading device connected to the apparatus main body 100A or a host device such as a personal computer connected to the apparatus main body 100A so as to be communicable, and a controller which is a “control unit” provided in the apparatus main body 100A. 100B is input.

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

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

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

  The photosensitive drum 1 and the charging roller 2, the developing unit 4, and the cleaning member 6 as process means acting on the photosensitive drum 1 are integrally formed into a cartridge to form a process cartridge 7. The process cartridge 7 can be attached to and detached from the apparatus main body 100A through mounting means such as a mounting guide and a positioning member provided in the apparatus main body 100A. Each color process cartridge 7 has the same shape, and each color process cartridge 7 has yellow (Y), magenta (M), cyan (C), and blank (K) colors. Toner is stored. In this embodiment, the process cartridge will be described, but the developing unit 4 may be detachable from the main body of the image forming apparatus alone.

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

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

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

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

  For example, when forming a full-color image, the above-described processes are sequentially performed in the first to fourth image forming units SY to SK, and the toner images of the respective colors are sequentially superimposed and primarily transferred onto the intermediate transfer belt 5. The Thereafter, the recording material 12 is conveyed to the secondary transfer portion N2 in synchronization with the movement of the intermediate transfer belt 5, and the operation of the secondary transfer roller 9 that is in contact with the intermediate transfer belt 5 through the recording material 12 is performed. Thus, the four-color toner images on the intermediate transfer belt 5 are secondarily transferred onto the recording material 12 at once. The recording material 12 onto which the toner image has been transferred is conveyed to a fixing device 10 as a fixing unit. The toner image is fixed on the recording material 12 by applying heat and pressure to the recording material 12 in the fixing device 10. 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 a desired single or some (not all) image forming units.

  FIG. 2 is a cross-sectional view of the process cartridge 7 as viewed from the axial direction of the photosensitive drum 1. Next, the overall configuration of the process cartridge 7 mounted on the image forming apparatus 100 of the present embodiment will be described. FIG. 2 is a cross-sectional view (main cross-sectional view) of the process cartridge 7 of this embodiment viewed along the longitudinal direction (rotational axis direction) of the photosensitive drum 1. In the first embodiment, the configuration and operation of the process cartridge 7 for each color are substantially the same except for the type (color) of the developer stored therein. The process cartridge 7 includes a photosensitive unit 13 including a photosensitive drum 1 that is an “image carrier” and a developing unit 4 that includes a developing roller 17 that is a “developer carrier”. Here, in the developing unit 4, a mechanism excluding the developing roller 17 and the supply roller 20 is referred to as a developer conveying device 4a.

  The photoreceptor unit 13 includes a photoreceptor drum 1, a charging roller 2, and a cleaning frame body 14. The cleaning frame 14 which is a “frame” supports various elements inside. The photosensitive drum 1 is rotatably attached to the cleaning frame 14 via a photosensitive drum bearing (not shown). The photosensitive drum 1 is rotationally driven in the direction of arrow A (clockwise) in accordance with the image forming operation by receiving the driving force of a driving motor (not shown) as a driving means (driving source).

  Further, a charging roller bearing (not shown) is attached to the cleaning frame body 14. Here, the charging roller bearing (not shown) is movably attached along a line passing through the rotation center of the charging roller 2 and the rotation center of the photosensitive drum 1. The charging roller 2 is rotatably attached to a charging roller bearing (not shown). The charging roller bearing (not shown) is urged toward the photosensitive drum 1 by a charging roller pressure spring (not shown) as an urging means. The charging roller 2 is in contact with the circumferential surface of the photosensitive drum 1.

  Further, a removal toner chamber 14 a is formed inside the cleaning frame body 14, and the cleaning member 6 is attached to the cleaning frame body 14. The transfer residual toner removed from the surface of the photosensitive drum 1 by the cleaning member 6 falls into the removed toner chamber 14a and is stored.

  The developing unit 4 includes a developing frame 18, a supply roller 20, a developing roller 17, and a developing blade 21. The developing frame 18 which is a “frame” supports various internal components. A developing roller 17, which is a “developer carrier” that rotates in the direction of arrow D (counterclockwise) in contact with the photosensitive drum 1 is attached to the developing frame 18. That is, a development side plate (not shown) is attached to each of both sides of the development frame 18. The developing roller 17 is rotatably supported by the developing frame 18 at both ends in the longitudinal direction (rotating axis direction) via the developing side plate (not shown). Further, the developing roller 17 and the photosensitive drum 1 rotate so that the surfaces of the developing roller 17 and the photosensitive drum 1 move in the same direction (in the first embodiment, the direction from the bottom to the top) in the opposing portion. Although the developing roller 17 is arranged in contact with the photosensitive drum 1, the developing roller 17 may be arranged close to the photosensitive drum 1 with a predetermined interval.

  The developing unit 4 is provided with a supply roller 20 that is a “developer supply body”, and the supply roller 20 rotates in the direction of arrow E (counterclockwise). The supply roller 20 is disposed so as to contact the circumferential surface of the developing roller 17. The supply roller 20 and the developing roller 17 rotate so that the surfaces of the supply roller 20 and the developing roller 17 move in opposite directions at the opposing portion (contact portion). The supply roller 20 has a function of supplying toner to the surface of the developing roller 17 and peeling off toner remaining on the surface of the developing roller 17 without being developed from the surface of the developing roller 17. Further, the developing unit 4 is provided with a developing blade 21 that is a “developer regulating member” that regulates the layer thickness of the toner supplied to the surface of the developing roller 17 by the supply roller 20. The developing blade 21 is disposed so as to contact the circumferential surface of the developing roller 17.

  The developing device frame 18 which is a “developer container” is a container for containing a developer. The developing frame 18 is a “first chamber” that stores a one-component developer, a toner storage chamber 18 a as a “developer storage chamber”, and an “adjacent chamber” that is a “second chamber” adjacent to the toner storage chamber 18 a. Is formed as a developing chamber 18b. A toner storage chamber 18a as a developer storage chamber formed inside the developing frame 18 stores a non-magnetic one-component developer, that is, toner as a developer. In addition, a conveying member 22 that is rotatably supported by the developing device frame 18 is disposed inside the toner storage chamber 18a. The transport member 22 can stir the toner stored in the toner storage chamber 18a and transport the toner to the developing chamber 18b. The first embodiment can also be applied to a toner container that includes only the toner storage chamber 18a and the conveyance member 22 and is configured as a developer container (toner cartridge) that can be attached to and detached from the apparatus main body 100A. The developing unit 4 is swingably coupled to the photosensitive unit 13 around a coupling shaft (not shown) that is provided in a developing side plate (not shown) and that fits into a hole (not shown). ing. At the time of image formation, the developing unit 4 is urged by a developing unit pressure spring 24 as urging means, and rotates clockwise about a coupling shaft (not shown). As a result, the developing roller 17 comes into contact with the photosensitive drum 1.

[One-component developer]
Next, the toner used in Example 1 will be described. The toner of Example 1 has a volume average particle size of 4.0 μm or more and 10.0 μm or less, and an average circularity of 0.950 or more. When the volume average particle diameter of the toner of this embodiment is less than 4 μm, the chargeability due to the deterioration of the fluidity of the toner particles tends to be non-uniform, for example, image fogging easily occurs in a high humidity environment. Therefore, there is concern. In addition, when the volume average particle diameter of the toner exceeds 10 μm, high-definition output becomes difficult, and there is a concern that the required image quality cannot be satisfied.

  For example, a Coulter Counter TA-II type or Coulter Multisizer II (manufactured by Beckman Coulter, Inc.) is used to measure the volume average particle diameter of the toner. The volume average particle diameter of the toner T can be measured with a measuring device in which an interface (manufactured by Nikka Ki Bios Co., Ltd.) for outputting the number distribution and volume distribution and a personal computer are connected. In this measurement, an electrolytic solution is used. For this electrolytic solution, for example, a 1% NaCl aqueous solution prepared using primary sodium chloride or ISOTON R-II (manufactured by Coulter Scientific Japan Co., Ltd.) can be used. .

  As a measurement method, 0.1 to 5 ml of a surfactant (preferably alkylbenzene sulfonate) is added as a dispersant to 100 to 150 ml of the electrolytic aqueous solution, and 2 to 20 mg of a measurement sample is further added. The electrolytic solution in which the sample is suspended is dispersed for about 1 minute with an ultrasonic disperser, and the volume distribution is determined by measuring the volume of toner of 2 μm or more with the Coulter Counter TA-II type using an aperture of 100 μm as an aperture. calculate. Then, the volume average particle diameter obtained from the volume distribution of this example is obtained.

  For the shape control of the toner of the present embodiment, it is preferable that the average circularity of the toner in the equivalent diameter-circularity scattergram based on the number of toners measured by the flow type particle image measuring apparatus is 0.950 or more. A toner having an average circularity of less than 0.950 means a toner whose shape has moved away from a spherical shape and has approached an indeterminate shape. Such irregular shaped toner tends to be crushed in the developing device during development, so that the particle size distribution fluctuates or the charge amount distribution becomes broad. This is not preferable because an undesired phenomenon such as an increase tends to occur.

  The circularity of the toner in this embodiment is used as a simple method for quantitatively expressing the shape of the toner particles. In the present Example, it measured using the flow type particle image measuring device FPIA-1000 type | mold (Toa Medical Electronics (made by Sysmex) Corporation), and computed using the following Formula. The measurement conditions were such that the toner particle concentration during measurement was adjusted to 5000 to 15000 particles / μl, and 1000 or more toner particles were measured.

  Circularity = (perimeter of a circle having the same area as the particle projection area) / (perimeter of the particle projection image). Here, the “particle projected area” is the area of the binarized toner particle image, and the “peripheral length of the particle projected image” is the length of the contour line obtained by connecting the edge points of the toner particle image. Define.

  As a specific measurement method, 10 ml of ion-exchanged water from which impure solids and the like are previously removed is prepared in a container, and a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant therein, and then further measurement is performed. Add about 0.02 g of sample and disperse uniformly. As a means to disperse, an ultrasonic disperser UH-50 type (manufactured by SMT Co., Ltd.) equipped with a titanium alloy tip of φ5 mm as a vibrator is used. A dispersion is obtained.

  As an achievement means for bringing the volume average particle diameter and the average circularity of the present embodiment into the preferred ranges of the present invention, in addition to a production method by a so-called pulverization method, a toner is produced using the following method or the like. It is also possible. That is, a method of directly producing toner using the suspension polymerization method disclosed in JP-A-36-10231 and JP-A-59-53856, or a heavy polymer that is soluble in a monomer. This is a dispersion polymerization method in which a toner is directly produced using a water-based organic solvent in which the coalescence is insoluble. Further, it is an emulsion polymerization method typified by a soap-free polymerization method in which a toner is produced by direct polymerization in the presence of a water-soluble polar polymerization initiator.

  In this embodiment, the shape of the toner can be easily controlled, and a suspension polymerization under normal pressure or under pressure, which can relatively easily obtain a fine particle toner having a sharp particle size distribution and a volume average particle size of 4 to 10 μm. The method was used. Then, styrene and n-butyl acrylate as monomers, a salicylic acid metal compound as a charge control agent, a saturated polyester as a polar resin, and a wax and a colorant were added to produce colored suspended particles. The toner particles have a volume average particle diameter of 6.5 μm and an average circularity of 0.980.

  Subsequently, the external additive attached to the developer base particles (hereinafter referred to as toner base particles), which is a feature of this embodiment, will be described below. Silica fine particles having an average primary particle size of 5 nm or more and less than 100 nm are 1.0 part by mass or more and less than 3.0 parts by mass with respect to 100 parts by mass of toner base particles (100 parts by mass of developer base particles). It is attached. Further, fine particles other than silica having an average primary particle size of 5 nm or more and less than 500 nm are externally added in an amount of less than 0.5 parts by mass with respect to 100 parts by mass of the toner base particles.

  When silica fine particles having an average primary particle size of 5 nm or more and less than 100 nm are not externally added, good toner fluidity cannot be obtained, and it becomes difficult to sufficiently charge the toner particles. Concerned. If good toner fluidity cannot be obtained, and toner particles are not sufficiently charged, there is a concern that problems such as increased fog, decreased image density, and toner scattering are likely to occur. .

  When silica fine particles having an average primary particle size of 5 nm or more and less than 100 nm are externally added to less than 1.0 part by mass with respect to 100 parts by mass of the toner base particles, when the developer is used for a long period of time, There is a concern that good toner fluidity cannot be obtained in the latter half of use of the developing unit. In such a case, there is a concern that it is difficult to sufficiently charge the toner particles. If the toner particles are not sufficiently charged, problems such as an increase in fog, a decrease in image density, and toner scattering are likely to occur.

  In addition, when silica fine particles having an average primary particle size of 5 nm or more and less than 100 nm are externally added to 3.0 parts by mass or more with respect to 100 parts by mass of the toner base particles, silica on the surface of the photoreceptor or developer carrying member There is a concern that contamination is likely to occur. When silica contamination occurs on the surface of the photosensitive member or the developer carrying member, it causes development problems due to fusion to the surface of the photosensitive member or contamination of the lower layer of the developer carrying member in continuous printing of images. There is concern.

  Thus, silica fine particles having an average primary particle size of 5 nm or more and less than 100 nm are externally added to 1.0 part by mass or more and less than 3.0 parts by mass with respect to 100 parts by mass of the toner base particles. Good toner fluidity can be obtained. Therefore, it is possible to sufficiently charge the toner particles.

  Here, in order to maintain the performance of each process of development, transfer, fixing, and cleaning, a small amount of other fine particles may be externally added to finely adjust the fluidity and chargeability of the toner. However, if the average primary particle size of the fine particles is 500 nm or more, it is easy to detach from the toner surface, and it becomes difficult to maintain the fluidity and chargeability of the toner for a long period of time, so the average primary particle size is 5 nm or more and less than 500 nm. It is preferable to externally add the fine particles.

  In addition, when fine particles having an average primary particle size of less than 5 nm are externally added, the fine particles have a high cohesive property and have a wide particle size distribution having a strong cohesive property that is difficult to break even by crushing treatment instead of the primary particles. It tends to behave as an aggregate. For this reason, there is a concern that the image is likely to be defective due to development of the aggregate, damage to the fixing member, the image carrier, the developer carrier, or the like.

  In general, if the fine particles having an average primary particle size of 5 nm or more and less than 500 nm are externally added to less than 0.5 parts by mass with respect to 100 parts by mass of the toner base particles, the average primary particle size is 5 nm or more and less than 100 nm. The effect of silica fine particles is great. Therefore, good toner fluidity and chargeability can be obtained. Thereby, a sufficiently good image can be output.

  Examples of the fine particles having an average primary particle size of 5 nm or more and less than 500 nm include the following. It is a lubricant powder such as Teflon powder, zinc stearate powder, polyvinylidene fluoride powder. It is also an abrasive such as cerium oxide powder, silicon carbide powder, strontium titanate powder. It is also a fluidity-imparting agent such as titanium oxide powder or aluminum oxide powder. It is also an anti-caking agent. In addition, it is a cleaning aid such as fine particles close to an inorganic or organic sphere such as spherical silica particles, spherical polymethylsilsesquioxane particles, and spherical resin particles. In addition, organic fine particles having opposite polarity and inorganic fine particles can be used in small amounts as a developability improver. These additives can also be used after hydrophobizing the surface.

  The method for measuring the average primary particle size of the external additive fine particles in this example is shown below. It is a photograph of the toner magnified with a scanning electron microscope, and contrasted with a photograph of the toner mapped with the elements contained in the external additive fine particles by elemental analysis means such as XMA attached to the scanning electron microscope. Done. Then, while comparing these photographs, 100 or more primary particles of the external additive fine particles adhering to or liberating from the toner surface are measured, and the number average particle diameter is obtained.

  The silica fine particles are preferably hydrophobized. For example, the surface of silica fine particles can be hydrophobized by treating with silicone oil. Silica fine particles are generally added to improve the fluidity of the toner and to make the toner base particles uniformly charged. By treating the inorganic fine particles with a silicone oil as in this embodiment, the following functions are achieved. Can be granted. The functions include not only adjustment of the toner charge amount and environmental stability, but also improvement of releasability from the fixing belt of this embodiment. It is more preferable that the silica fine particles are hydrophobized in order to keep the charge amount of the toner particles high even in a high-humidity environment and to prevent toner scattering.

  In the present invention, 1.5 parts by mass of silica A having an average primary particle diameter of 10 nm and 0.4 parts by mass of silica B having an average primary particle diameter of 50 nm are weighed with respect to 100 parts by mass of toner base particles. By dry mixing, toners of Examples and Comparative Examples were obtained.

  FIG. 3A is a cross-sectional view showing the configuration of the developing unit 4 and shows a state in which the toner holding portion 22f is in contact with the floor side inner wall portion 18a1. In addition, as for the configuration and operation of the developing unit 4 or the process cartridge 7, the terms representing the directions such as up, down, vertical, and horizontal are those in the normal use state on the drawing unless otherwise specified. Represents a direction. That is, the normal use state of the developing unit 4 or the process cartridge 7 is a state in which the developing unit 4 or the process cartridge 7 can be properly mounted on the properly arranged image forming apparatus main body and used for an image forming operation.

  In the developing unit 4, a toner storage chamber 18a and a developing chamber 18b are formed. In the developing chamber 18b, a developing roller 17, a supply roller 20, a developing blade 21, and the like are accommodated. The toner storage chamber 18a is provided with a transport member 22 that stores toner supplied to the development chamber 18b and supplies toner to the development chamber 18b. The toner storage chamber 18a is disposed below the developing chamber 18b in the vertical direction. Therefore, it is necessary to convey the toner against the gravity from the toner storage chamber 18a to the development chamber 18b.

  As described above, conventionally, when the toner is transported against gravity, it has been difficult to obtain a good toner transport efficiency with a simple and easy-to-support structure. If a toner supply failure to the developing chamber 18b in which the developing roller 17 and the supply roller 20 are provided occurs, an image defect such as an image white defect (a phenomenon in which the toner is not locally deposited on the output image) occurs. . Therefore, in the case where the toner is transported against gravity, it is desirable to suppress image defects such as image blank due to poor toner supply with a simple, low-cost, and compact structure.

  Therefore, in the first embodiment, the developing unit 4 has the following configuration. That is, the developing unit 4 includes a developing chamber 18 b and a toner storage chamber 18 a that are formed inside the developing frame 18. A developing roller 17 and a supply roller 20 are provided in the developing chamber 18b. Further, the toner storage chamber 18a is disposed below the developing chamber 18b. Here, the toner storage chamber 18a stores toner to be supplied to the developing chamber 18b. A partition wall 26 that partitions the toner storage chamber 18a and the development chamber 18b is formed between the development chamber 18b and the toner storage chamber 18a. The partition wall 26 is formed with an opening 18 c that penetrates the partition wall 26. Here, the opening 18c is provided above the toner storage chamber 18a. In addition, a conveyance member 22 having elasticity for supplying toner to the developing chamber 18b is rotatably provided in the toner storage chamber 18a.

  As shown in FIG. 3A, the toner storage chamber 18a has a floor-side inner wall portion 18a1, a guide portion 18a2 which is a “deformation portion”, and a restoration portion 18a4 which is a “restoration portion”. Toner is stored in the toner storage chamber 18a. The floor side inner wall portion 18a1 is a curved surface that abuts when the toner is stored and the conveying member 22 rotates. When the conveying member 22 rotates, the tip of the conveying member 22 comes into contact with the floor-side inner wall portion 18a1, but the contact force does not increase or decrease, and the deformation amount of the conveying member 22 is substantially constant. The toner thus scooped up is conveyed downstream in the rotation direction of the conveying member 22.

  The guide portion 18a2 that is a “deformation portion” is a plate surface that abuts when the transport member 22 rotates. That is, the guide portion 18a2 is a plate surface that deforms the conveying member 22 by increasing a reaction force applied to the conveying member 22 corresponding to an increase in the contact force accompanying the rotation of the conveying member 22. For this reason, when the conveying member 22 rotates, the leading end of the conveying member 22 abuts on the guide portion 18a2, and the abutting force increases, and the conveying member 22 is deformed by an increase in the reaction force of the guide portion 18a2.

  The restoration part 18a4 which is a "restoration part" is a plate surface that comes into contact when the transport member 22 rotates. That is, the restoring portion 18 a 4 is a plate surface that reduces the reaction force applied to the transport member 22 in response to a decrease in contact force accompanying the rotation of the transport member 22 and restores the transport member 22. For this reason, when the conveying member 22 rotates, the leading end of the conveying member 22 is separated from the restoring portion 18a4 and the contact force is reduced, and the conveying member 22 is restored by a decrease in the reaction force of the restoring portion 18a4.

  The guide part 18a2 and the restoring part 18a4 are formed in a straight line in a cross-sectional view. A boundary portion q is defined at the boundary between the guide portion 18a2 and the restoration portion 18a4. The boundary part q is provided below the lower end of the opening 18c. In addition, a lower corner s is formed at the boundary between the floor inner wall 18a1 and the guide 18a2, and an upper corner t that is bent toward the opening 18c is formed at the upper end of the restoring portion 18a4. .

  Further, as shown in FIG. 3A, a conveying member 22 is rotatably disposed inside the toner storage chamber 18a. The transport member 22 has a transport support shaft 22b that is a “rotary shaft” that is disposed below the opening 18c and is rotatable within the toner storage chamber 18a. The transport support shaft 22b receives a rotational driving force from a driving means (not shown). Further, the transport member 22 has a sheet portion 22a having a base end portion fixed to the transport support shaft 22b and extending in a plate shape and having elasticity (flexibility). Further, the conveying member 22 is a “developer holding portion” having a recess 22f1 formed on the surface of the sheet portion 22a in the rotation radius direction and on the surface in the rotation direction side of the sheet portion 22a and capable of holding the developer. A toner holding portion 22f is provided. The recess 22f1 scoops out toner.

  The transport 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 conveying member 22 is rotationally driven in the rotational direction G (clockwise) by a driving means (drive source) (not shown). The transport member 22 transports toner from the toner storage chamber 18a to the development chamber 18b by rotation. 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 supply roller 20. The sheet portion 22a is a continuous sheet (plate-like member) that extends over substantially the entire region in the longitudinal direction (rotational axis direction) of the conveyance support shaft 22b. The sheet portion 22a is attached to the conveyance support shaft 22b at one end (base end portion) in a direction (rotational radius direction) substantially orthogonal to the longitudinal direction of the conveyance support shaft 22b. Moreover, the sheet | seat part 22a can be suitably produced, for example using flexible resin-made sheets, such as a polyester film, a polyphenylene sulfide film, and a polycarbonate film. The thickness of the sheet portion 22a is preferably 50 μm to 250 μm.

  The toner holding portion 22f has a recess 22f1 on the upstream surface in the rotation direction. The toner holding portion 22f is a continuous concave member that extends over substantially the entire region in the longitudinal direction (rotational axis direction) of the conveyance support shaft 22b. The toner holding portion 22f is provided at a position near the inner wall of the toner storage chamber 18a in the sheet portion 22a. Side walls are provided at both ends in the longitudinal direction of the toner holding portion 22f to prevent the toner inside the toner holding portion 22f from spilling from the side surface. The toner holding portion 22f may be manufactured using a resin sheet such as acrylic resin, polycarbonate resin or polyacetal resin, polyethylene terephthalate resin (PET), polyolefin resin, polystyrene resin, polyester resin. The thickness of the toner holding part 22f is preferably 50 μm to 1000 μm.

Further, as shown in FIG. 4A, in a state where the recess 22f1 and the opening 18c face each other, the recess 22f1 and the opening 18c are set to overlap at least partially in the swinging direction (movement direction) of the recess 22f1. ing. When the conveying member 22 rotates, the developer passes through the opening 18c from the toner storage chamber 18a and is conveyed to the developing chamber 18b. When the conveying member 22 rotates, at least a part of the toner holding portion 22f is set to overlap the opening portion 18c. Further, as shown in FIG. 4B, when the conveying member 22 and the partition wall 26 come into contact with each other, the following is performed. That is, the angle α formed by the first direction J perpendicular to the plane along the opening 18c and the second direction K indicating the moving direction immediately before the contact of the toner holding portion 22f is 10 °. That is, the first direction J and the second direction K are substantially parallel.

  Next, with reference to FIGS. 3A to 4B, the operation of the conveying member 22 inside the developing unit 4 will be described in detail. As shown in FIG. 3A, a toner holding portion 22 f is formed on the leading end side of the sheet portion 22 a of the conveying member 22. The toner holding portion 22f is in contact with the floor side inner wall portion 18a1 near the lowermost portion of the toner storage chamber 18a. In this state, when the conveying member 22 rotates, the toner that can be held from the vicinity of the lowermost portion of the toner storage chamber 18a can be scooped into the recess 22f1 of the toner holding portion 22f.

  FIG. 3B is a cross-sectional view showing the configuration of the developing unit 4, and shows a state where the toner holding portion 22f is in contact with the guide portion 18a2. As shown in FIG. 3B, the toner storage chamber 18a is formed with a guide portion 18a2 which is a “deformation portion” and a restoration portion 18a4 which is a “restoration portion”. The guide portion 18a2 is a linear portion of the inner wall of the toner storage chamber 18a and refers to the inner wall surface from the lower corner portion s to the boundary portion q. The restoring portion 18a4 is a linear portion of the inner wall of the toner storage chamber 18a, and indicates the inner wall surface from the boundary portion q to the upper corner portion t.

  When the toner holding portion 22f of the conveying member 22 rotates while contacting the guide portion 18a2, the reaction force received by the conveying member 22 from the guide portion 18a2 increases. As a result, particularly the sheet portion 22a of the conveying member 22 is deformed against the elastic force of the conveying member 22. At this time, the movement of the toner scooped into the concave portion 22f1 of the toner holding portion 22f is restricted by the inner wall of the toner holding portion 22f and the guide portion 18a2, so that the rotation direction is stored in the toner holding portion 22f. It is conveyed to the downstream side. At the same time, the toner accumulated in the portion of the sheet portion 22a closer to the conveyance support shaft 22b than the toner holding portion 22f falls in the direction of arrow P in FIG.

  When the conveying member 22 rotates while contacting the restoring portion 18a4, the reaction force received by the conveying member 22 from the restoring portion 18a4 decreases. As a result, the conveying member 22 is restored by the elastic force of the conveying member 22. The restoring portion 18a4 is provided in the toner storage chamber 18a on the downstream side of the guide portion 18a2 and the upstream side of the opening portion 18c in the rotation direction of the conveying member 22. The restoring portion 18a4 can also be said to be a portion for releasing the contact between the conveying member 22 and the inner wall of the toner storage chamber 18a. The restoration unit 18a4 indicates a portion from the boundary q to the upper corner t of the inner wall of the toner storage chamber 18a. As the conveyance member 22 rotates, the free end of the conveyance member 22 passes through the boundary portion q while contacting the restoring portion 18a4, and the conveyance member 22 passes through the inner wall of the toner storage chamber 18a. It is released from the contact state with respect to. Then, the conveying member 22 is released from the state of being deformed by the guide portion 18a2, and is restored to the natural state (original shape) by its own elastic restoring force.

  FIG. 4A is a cross-sectional view showing the configuration of the developing unit 4, and shows a state where the toner holding portion 22f faces the opening 18c. As shown in FIG. 4A, when the transport member 22 further rotates, the recess 22f1 of the transport member 22 faces the opening 18c, and a state immediately before the transport member 22 contacts the partition wall 26 is reached. The toner that has accumulated on the sheet portion 22a closer to the conveyance support shaft 22b than the toner holding portion 22f falls in the direction of arrow P in FIG. At this time, the toner holding portion 22f quickly accelerates in the rotation direction of the conveying member 22 due to the shape change that the conveying member 22 restores, but the toner inside the concave portion 22f1 is strongly pressed against the inner wall of the concave portion 22f1 and strongly held. The toner does not go out of the toner holding portion 22f.

FIG. 4B is a cross-sectional view showing the configuration of the developing unit 4 and shows a state in which the sheet portion 22 a has abutted against the partition wall 26. As shown in FIG. 4B, the above-described opening 18c is located downstream of the restoring portion 18a4 in the rotation direction of the transport member 22. Moreover, the boundary part q is provided below the lowest end of the opening part 18c. Then, when the conveying member 22 passes through the boundary portion q, the conveying member 22 is restored based on the elastic force of the conveying member 22, and the sheet portion 22a is a region below the opening 18c in the partition wall 26 ("developer container contact portion"). Rotates all the way to a position where it can be touched. Therefore, at the moment when the conveying member 22 passes through the boundary portion q, the conveying member 22 hits the partition wall 26 around the opening 18c with an elastic force. When the sheet portion 22a hits the partition wall 26, the toner holding portion 22f rapidly decelerates, but the toner inside the toner holding portion 22f receives a circumferential force due to inertial force and is released to the outside of the toner holding portion 22f. Is done.

Further, the following can be said in a state where the conveying member 22 is in contact with the partition wall 26. That is, the first direction J perpendicular to the plane along the opening 18c and the second direction K in which the recess 22f1 swings when the sheet portion 22a contacts the partition wall 26 (developer container contact portion) are substantially parallel. It is. As a result, the toner released to the outside of the toner holding portion 22f efficiently enters the developing chamber 18b through the opening 18c.

  With this configuration and operation, a constant toner amount can be held in the toner holding portion 22f from the bottom of the toner storage chamber 18a regardless of the toner amount inside the toner storage chamber 18a. For this reason, the toner is efficiently and satisfactorily conveyed against the gravity from the toner storage chamber 18a to the developing chamber 18b with a simpler configuration that can easily cope with downsizing.

  Other features are described in further detail below. As shown in FIG. 4B, a supply roller 20 is disposed in the developing chamber 18b at a position facing the opening 18c. The toner inside the toner storage chamber 18a is conveyed to the developing chamber 18b through the opening 18c. The supply roller 20 rotates in the direction in which the surface moves from top to bottom at the portion facing the opening 18c. By this rotation, the supply roller 20 takes in the toner supplied to the developing chamber 18 b through the opening 18 c downward along the partition wall 26. The lower end of the opening 18 c is disposed above the lower end of the supply roller 20. With this arrangement, the toner surface (the surface of the toner as a group) of the toner stored in the developing chamber 18b depends on the lower end of the opening 18c. Therefore, the toner surface is above the lower end of the supply roller 20. For this reason, the contact area between the surface of the supply roller 20 and the toner increases, and the efficiency of supplying toner to the supply roller 20 is improved.

  FIG. 5 is a cross-sectional view showing the configuration of the conveying member 22 and the opening 18c as seen from the direction of the arrow V in FIG. The length M in the longitudinal direction of the toner holding portion 22f shown in FIG. 5 is preferably longer than the length N in the longitudinal direction of the opening 18c. As a result, the portion of the toner holding portion 22f that is farthest from the rotation center of the conveying member 22 is prevented from being caught by the lower end of the opening 18c, and the movement of the conveying member 22 is prevented from becoming unstable.

[Effect of Example 1]
According to the configuration of the first embodiment described above, the toner can be efficiently and satisfactorily conveyed against the gravity from the toner storage chamber 18a to the developing chamber 18b with a configuration that is simpler and can easily cope with downsizing. Further, regardless of the toner amount inside the toner storage chamber 18a, a constant toner amount can be held in the toner holding portion 22f from the lowermost portion of the toner storage chamber 18a. Therefore, regardless of the amount of toner inside the toner storage chamber 18a, the toner can be efficiently and satisfactorily conveyed from the toner storage chamber 18a to the developing chamber 18b against gravity.

  A simple configuration will be described in detail. According to the configuration of the first exemplary embodiment, the conveyance member 22 substantially holds the toner in the toner storage chamber 18a while conveying the toner to the opening 18c while holding the toner in the toner storage chamber 18a, the conveyance support shaft 22b that supports the sheet portion 22a. The toner holding unit 22f is a simple configuration. Therefore, it is a cheaper configuration as compared with a configuration using, for example, a screw or the like as means for conveying the toner upward.

  The downsizing will be described in detail. According to the configuration of the first exemplary embodiment, since the elastic sheet portion 22a is used for the conveying member 22, the toner is jumped up by the elastic restoring force of the sheet portion 22a while being held by the toner holding portion 22f. Since the sheet portion 22a can be elastically deformed, the width of the process cartridge in the left-right direction can be reduced in FIG. Therefore, for example, the width of the toner storage chamber 18a can be reduced and the size can be reduced as compared with a configuration in which the toner storage chamber 18a has a substantially circular cross section and the transfer member transfers the toner to the developing chamber 18b while holding the toner. it can. Further, along with the miniaturization of the toner storage chamber 18a, the development unit 4, the process cartridge 7, and the image forming apparatus 100 can be miniaturized.

  According to the configuration of the first embodiment described above, the toner can be transported satisfactorily against gravity, so that, for example, a configuration in which the process cartridge 7 is disposed below the intermediate transfer belt 5 in the vertical direction can be realized. . As a result, for example, the scanner unit 3 and the fixing device 10 can be arranged at a distance from each other, and the influence of the heat of the fixing device 10 on the scanner unit 3 is reduced. Further, the space for reducing the influence of the heat of the fixing device 10 on the scanner unit 3 can be eliminated or reduced. As a result, the image forming apparatus 100 can be reduced in size, for example, by suppressing the height of the image forming apparatus 100. Further, the fixing device 10 can be arranged at a position away from the developing unit 4 and the process cartridge 7 with the intermediate transfer belt 5 interposed therebetween. For this reason, the influence of the heat of the fixing device 10 on the developing unit 4 and the process cartridge 7 is reduced. A space for reducing the influence of the heat of the fixing device 10 on the developing unit 4 or the process cartridge 7 is eliminated or reduced. As a result, the image forming apparatus 100 can be reduced in size, for example, by suppressing the height of the image forming apparatus 100.

  FIG. 6 is a cross-sectional view illustrating the configuration of the developing unit 204 according to the second embodiment, in which the toner holding portion 22f is in contact with the floor-side inner wall portion 18a1. Among the configurations of the developing unit 204 of the second embodiment, the same configurations and effects as those of the developing unit 4 of the first embodiment are denoted by the same reference numerals, and description thereof is omitted as appropriate. Since the second embodiment can be applied to the same image forming apparatus as that of the first embodiment, the description of the image forming apparatus is omitted. The developing unit 204 of the second embodiment is different from the developing unit 4 of the first embodiment in that a partition wall protrusion 26 a that contacts the conveyance member 22 is attached to a part of the surface of the partition wall 26.

  The partition wall projection 26a, which is a “developer container contact portion”, is disposed above the transport support shaft 22b and below the opening 18c in the partition wall 26, and is configured to be able to contact the sheet portion 22a. . When the sheet portion 22a comes into contact with the partition wall projection 26a, the recess 22f1 swings toward the opening 18c with the contact point between the sheet portion 22a and the partition wall projection 26a as a fulcrum. Further, the dimension between the partition wall protrusion 26a and the conveyance support shaft 22b is a dimension that allows the sheet part 22a and the toner holding part 22f to pass while elastically deforming when the sheet part 22a contacts the partition wall protrusion 26a. Is set to

  As shown in FIG. 6, when the toner holding part 22f passes near the lowermost part of the toner storage chamber 18a, the conveying member 22 rotates, so that the toner holding part 22f has toner in the concave part 22f1. Will be scolded.

  FIG. 7A is a cross-sectional view showing the configuration of the developing unit 204, and shows a state where the toner holding portion 22f is in contact with the guide portion 18a2. The toner scooped inside the toner holding portion 22f is restricted in movement by the inner wall of the toner holding portion 22f and the guide portion 18a2, so that the toner is held in the concave portion 22f1 on the downstream side in the rotation direction of the conveying member 22. It is conveyed by. At the same time, the toner accumulated on the sheet portion 22a closer to the conveyance support shaft 22b than the toner holding portion 22f falls in the direction of the arrow P. Up to this point, the operation is the same as that of the first embodiment.

  FIG. 7B is a cross-sectional view showing the configuration of the developing unit 204, and shows a state in which the sheet portion 22a is in contact with the partition wall protrusion 26a. As shown in FIG. 7B, at the moment when the conveying member 22 contacts the partition wall projection 26a, the conveyance support shaft 22b in the sheet portion 22a out of the positions where the sheet portion 22a and the partition wall projection 26a contact. The closest contact portion 22a1 closest to the contact will come into contact.

  Here, the part which contacts the conveyance member 22 among the partition wall protrusion parts 26a is referred to as a contact angle part 26a1. The contact corner 26a1 is located below the opening 18c and above the rotation center of the transport support shaft 22b. The toner holding portion 22f is the closest to the conveyance support shaft 22b (rotation center) of the conveyance member 22 closest to the conveyance support shaft 22b (rotation center) of the sheet portion 22a that is in contact with the partition wall projection 26a, and the conveyance support shaft 22b of the conveyance member 22 is closest. It is set between the (rotation center) and the far part.

  Until just before the conveying member 22 and the partition wall 26 come into contact, the toner holding portion 22f is quickly accelerated by the shape change of the conveying member 22 in the restoring direction. However, the toner inside the concave portion 22f1 of the toner holding portion 22f is strongly pressed against the inner wall of the toner holding portion 22f and is strongly held, and does not go out of the toner holding portion 22f.

  On the other hand, when the partition wall projection 26a is provided on the partition wall 26, the following effects are obtained. That is, the conveyance member 22 rotates and the sheet portion 22a comes into contact with the partition wall protrusion 26a. Then, the closest contact portion 22a1 to the toner holding portion 22f with the partition wall projection 26a closest to the conveying member 22 in the sheet portion 22a is located downstream of the rotation direction of the sheet portion 22a with the closest contact portion 22a1 as a fulcrum. Deform. Then, the toner inside the toner holding unit 22f is vigorously discharged out of the toner holding unit 22f in the moving direction immediately before the contact of the toner holding unit 22f.

  Similarly to the case of FIG. 4B, when the conveying member 22 and the partition wall projection 26a come into contact with each other, the first direction J perpendicular to the plane along the opening 18c and immediately before the contact with the toner holding unit 22f. The second direction K indicating the moving direction is substantially parallel. Thereby, the toner released out of the toner holding portion 22f efficiently enters the developing chamber 18b through the opening 18c.

  With this configuration and operation, a constant toner amount can be held in the toner holding portion 22f from the bottom of the toner storage chamber 18a regardless of the toner amount inside the toner storage chamber 18a. For this reason, the toner is efficiently and satisfactorily conveyed against the gravity from the toner storage chamber 18a to the developing chamber 18b with a simpler configuration that can easily cope with downsizing.

  FIG. 8A is a cross-sectional view showing a configuration of the developing unit 64 according to the first comparative example, and shows a state in which the leading end of the sheet portion 22a is in contact with the floor side inner wall portion 18a1. The developing unit 64 of the first comparative example is different from the developing unit 4 of Examples 1 and 2 in that the toner holding unit 22f is not provided. As shown in FIG. 8A, the contact angle θ at which the front end of the sheet portion 22a contacts the vicinity of the lowermost portion of the floor side inner wall portion 18a1 of the toner storage chamber 18a is 60 °. As described above, since the contact angle θ is large, when the transport member 22 rotates, the toner near the lowermost portion of the toner storage chamber 18a is lifted up to the guide portion 18a2.

  FIG. 8B is a cross-sectional view showing the configuration of the developing unit 64 according to the first comparative example, and shows a state in which the leading end of the sheet portion 22a is in contact with the guide portion 18a2. As shown in FIG. 8B, among the toner pumped up by the sheet portion 22a, the movement of the toner on the leading end side in the rotational radius direction of the sheet portion 22a is limited by the conveying member 22 and the guide portion 18a2. It is conveyed while being held on the downstream side in the rotation direction of the conveying member 22. At the same time, of the toner lifted by the sheet portion 22a, the toner on the rotation center side of the sheet portion 22a falls in the direction of the arrow P.

  FIG. 9 is a cross-sectional view illustrating a configuration of the developing unit 64 according to the first comparative example, and illustrates a state immediately before the leading end of the sheet portion 22a contacts the partition wall 26. As shown in FIG. 9, the contact of the conveying member 22 with the inner wall of the toner storage chamber 18a is released after the free end of the conveying member 22 passes through the guide portion 18a2 as the conveying member 22 rotates. Is done. Then, the conveying member 22 is released from the state of being deformed by the guide portion 18a2, and is restored to the natural state (original shape) by its own elastic restoring force. Due to the shape change of the conveying member 22 in the restoring direction, the toner carried and conveyed on the conveying member 22 flies against the gravity toward the opening 18c. The opening 18c is located downstream of the restoring portion 18a4 in the rotation direction of the conveying member 22.

  When the transport member 22 passes through the boundary portion q, the transport member 22 is rotated to a position where it can come into contact with the periphery of the opening portion 18c by restoration due to its elastic force. Therefore, at the moment when the conveying member 22 is separated from the boundary portion q, the conveying member 22 hits the periphery of the opening 18c with its elastic force. Thereby, the toner can fly to the opening 18c.

  However, among the toners lifted by the conveying member 22 until the conveying member 22 moves away from the boundary q and hits the periphery of the opening 18c, the toner on the rotation center side of the conveying member 22 is indicated by the arrow P in FIG. Fall in the direction. Further, among the toner lifted by the conveying member 22, most of the toner on the free end side of the conveying member 22 is pushed out by centrifugal force because the toner cannot be held on the conveying member 22, and FIG. It falls in the direction of arrow Q inside.

  That is, there is nothing other than the conveying member 22 that restricts the movement of the toner until the conveying member 22 hits the periphery of the opening 18c after passing through the boundary portion q. For this reason, the toner on the transport member 22 is likely to dissipate outside the opening 18c, and it is difficult to efficiently transport the toner from the toner storage chamber 18a to the developing chamber 18b against gravity.

  Here, of the toner lifted up to the guide portion 18a2 by the transport member 22, the proportion of the toner that can be transported to the opening portion 18c is substantially constant. Therefore, when the amount of toner in the toner storage chamber 18a is small, the amount of toner that the transport member 22 lifts up to the guide portion 18a2 is reduced, so that the toner can be efficiently transported from the toner storage chamber 18a to the development chamber 18b against gravity. Is particularly difficult.

  FIG. 10A is a cross-sectional view showing a configuration of the developing unit 74 according to the second comparative example, and shows a state in which the leading end of the sheet portion 22a is in contact with the floor side inner wall portion 18a1. The development unit 74 of the second comparative example is different from the development unit 4 of Examples 1 and 2 in that the toner holding unit 22f is not provided and the sheet unit 22a is not directly attached to the conveyance support shaft 22b. . In the developing unit 74 of the second comparative example, a sheet attaching portion 22c that is not deformed even when a force is applied is attached to the conveyance support shaft 22b. Further, the sheet portion 22a is attached to a portion farthest from the rotation center of the sheet attaching portion 22c.

  As shown in FIG. 10A, the contact angle θ at which the tip of the sheet portion 22a contacts the vicinity of the lowermost portion of the floor side inner wall portion 18a1 of the toner storage chamber 18a is 45 °. As described above, since the contact angle θ is small, a large amount of toner in the vicinity of the toner storage chamber 18a cannot be lifted up to the guide portion 18a2 even if the conveying member 22 rotates.

  FIG. 10B is a cross-sectional view showing the configuration of the developing unit 74 according to the second comparative example, and shows a state in which the leading end of the sheet portion 22a is in contact with the guide portion 18a2. As shown in FIG. 10B, among the toners lifted by the conveyance member 22, the movement of the toner on the free end side of the conveyance member 22 is restricted by the conveyance member 22 and the guide portion 18 a 2. It is conveyed while being held downstream in the rotation direction. However, the contact angle θ between the sheet portion 22a and the guide portion 18a2 is 23 °. As described above, since the contact angle θ is small, even if the conveying member 22 rotates, it is not possible to convey all of the toner on the free end side of the conveying member 22. Of the toner lifted by the conveying member 22, the toner on the rotation center side of the conveying member 22 falls in the direction of arrow P in FIG.

  FIG. 11A is a cross-sectional view showing a configuration of the developing unit 74 according to the second comparative example, and shows a state in which the leading end of the sheet portion 22a passes through the boundary portion q. As shown in FIG. 11A, when the leading end of the sheet portion 22a passes through the boundary portion q, the contact state between the sheet portion 22a and the inner wall of the toner storage chamber 18a is released. Then, the conveying member 22 is released from the state of being deformed by the guide portion 18a2, and is restored to the natural state (original shape) by its own elastic restoring force.

  However, the free end of the conveying member 22 can only rotate to a position that is not in contact with the periphery of the opening 18c, even if it is restored by its elasticity when it is separated from the boundary q. In other words, the toner on the free end side of the conveying member 22 cannot fly to the opening 18c by using the elastic force of the conveying member 22.

  FIG. 11B is a cross-sectional view showing a configuration of the developing unit 74 according to the second comparative example, and shows a state in which the leading end of the sheet portion 22 a is in contact with the partition wall 26. As shown in FIG. 11B, the toner remaining on the free end side of the sheet portion 22a is also rubbed by the partition wall 26 at the lower end of the opening 18c, and is moved in the direction of arrow Q in FIG. Fall.

  Thus, the toner on the free end side of the sheet portion 22a cannot be caused to fly to the opening portion 18c by using the elastic force of the sheet portion 22a. Further, the toner remaining on the free end side of the sheet portion 22a is also rubbed and dropped by the partition wall 26 at the lower end of the opening portion 18c, so that the toner is efficiently conveyed from the toner storage chamber 18a to the developing chamber 18b against gravity. Difficult to do.

  FIG. 12A is a cross-sectional view showing a configuration of the developing unit 84 according to the third comparative example, and shows a state in which the front end of the sheet portion 22a is in contact with the floor side inner wall portion 18a1. The development unit 84 of the third comparative example is different from the development unit 4 of Example 1 and Example 2 in that the toner holding part 22f is not provided and the conveyance member protrusion part 22d is provided on the sheet part 22a. . As shown in FIG. 12A, in the developing unit 84 of the third comparative example, when the conveying member 22 comes into contact with the floor side inner wall portion 18a1 in the vicinity of the lowermost portion of the toner storage chamber 18a, the sheet portion 22a The contact angle θ at which the tip contacts the vicinity of the lowermost portion of the toner storage chamber 18a is 60 °. As described above, since the contact angle θ is large, when the transport member 22 rotates, the toner near the lowermost portion of the toner storage chamber 18a is lifted up to the guide portion 18a2.

  FIG. 12B is a cross-sectional view illustrating a configuration of the developing unit 84 according to the third comparative example, and illustrates a state in which the leading end of the sheet portion 22a is in contact with the guide portion 18a2. As shown in FIG. 12B, of the toner lifted by the conveying member 22, the toner on the free end side with respect to the conveying member protruding portion 22d moves by the conveying member protruding portion 22d, the conveying member 22, and the guide portion 18a2. Is limited. Therefore, it is conveyed in a state of being held on the downstream side in the rotation direction of the conveying member 22. However, of the toner lifted by the conveying member 22, the toner closer to the rotation center than the conveying member protrusion 22d falls in the direction of arrow P in FIG.

  FIG. 13 is a cross-sectional view illustrating a configuration of the developing unit 84 according to the third comparative example, and illustrates a state immediately before the leading end of the sheet portion 22a contacts the partition wall 26. As the transport member 22 rotates, the free end of the transport member 22 passes through the guide portion 18a2, and then the contact between the sheet portion 22a and the inner wall of the toner storage chamber 18a is released. Then, the conveying member 22 is released from the state of being deformed by the guide portion 18a2, and is restored to the natural state (original shape) by its own elastic restoring force. Due to the shape change of the conveying member 22 in the restoring direction, the toner carried and conveyed on the conveying member 22 flies against the gravity toward the opening 18c. The opening 18c is located downstream of the restoring portion 18a4 in the rotation direction of the conveying member 22.

  When the conveying member 22 is separated from the boundary portion q, the conveying member 22 is rotated to a position where it can come into contact with the periphery of the opening 18c due to its elastic recovery. Therefore, at the moment when the conveying member 22 is separated from the boundary portion q, the conveying member 22 hits the periphery of the opening 18c with its elastic force. Thereby, the toner can fly to the opening 18c.

  However, of the toner lifted by the conveying member 22 until the conveying member 22 moves away from the boundary q and hits the periphery of the opening 18c, the toner on the free end side of the conveying member protrusion 22d is transferred to the conveying member 22. The toner cannot be retained. For that purpose, most is pushed outward by centrifugal force and falls in the direction of arrow Q in FIG.

  That is, there is nothing that restricts the movement of the toner other than the conveyance member 22 and the conveyance member protrusion 22d until the conveyance member 22 moves away from the boundary portion q and hits the periphery of the opening 18c. For this reason, the toner on the transport member 22 is likely to dissipate outside the opening 18c, and it is difficult to efficiently transport the toner from the toner storage chamber 18a to the developing chamber 18b against gravity.

  Here, of the toner lifted up to the guide portion 18a2 by the transport member 22, the proportion of the toner that can be transported to the opening portion 18c is substantially constant. Therefore, when the amount of toner in the toner storage chamber 18a is small, the amount of toner that the transport member 22 lifts up to the guide portion 18a2 is reduced, so that the toner can be efficiently transported from the toner storage chamber 18a to the development chamber 18b against gravity. Is particularly difficult.

[Method for evaluating toner supply from toner storage chamber to developing chamber]
In the present invention, the following method is used to evaluate the supply of toner from the toner storage chamber 18a to the developing chamber 18b. The toner consumption rate from the developing chamber 18b is the fastest when continuous images are output continuously. If the toner supply speed from the toner storage chamber 18a to the development chamber 18b is insufficient, the toner consumption speed from the inside of the development chamber 18b is higher than the toner supply speed from the toner storage chamber 18a to the development chamber 18b. In addition, toner shortage inside the developing chamber 18b occurs. If the amount of toner in the developing chamber 18b is too small, when a solid image is output, the solid image is whitened due to insufficient toner. In the present invention, even if solid images are output continuously, the solid image is realized so that it does not fall out white due to toner shortage. Therefore, the supply of toner from the toner storage chamber 18a to the developing chamber 18b is evaluated by continuously outputting solid images and checking the presence or absence of image defects in the solid images. This will be described in detail below.

  The solid image evaluation was performed after printing the 100 sheets after allowing the image forming apparatus to stand in the evaluation environment at 23 ° C. and 50% Rh for one day to adjust to the environment. The printing test for 100 sheets was performed by continuously passing a horizontal line recorded image having an image ratio of 5%. For the image evaluation, three solid images were continuously output, and evaluation was performed using a SpectroDensitometer 500 manufactured by X-Rite from the density difference between the output leading edge and the trailing edge of the third solid image. The print test and evaluation image were output in a single color. In addition, two levels (200 g and 50 g) of toner amounts to be filled in the toner storage chamber 18a are set and compared. In the evaluation, ◯ indicates that the density difference between the leading edge of the paper and the trailing edge of the paper is less than 0.2 in the solid image, and Δ indicates that the density difference between the leading edge of the paper and the trailing edge of the paper is 0.2 to If it is less than 0.4, x means that the density difference between the leading edge of the paper and the trailing edge of the paper is 0.4 or more in the solid image.

[Evaluation results of Examples 1 to 2 and First Comparative Example to Third Comparative Example]
Table 1 shows a comparison table of evaluation results applied to Examples 1 to 2 and First Comparative Example to Third Comparative Example based on the above-described evaluation method.

実施例１では、トナー収納室１８ａに充填するトナー量が２００ｇ、５０ｇ両方の条件で評価結果を導出したが、トナー収納室１８ａから現像室１８ｂへのトナーの供給が共に充分であった。以下で原理を説明する。まず、搬送部材２２が回転することで、トナー保持部２２ｆの内部に、トナー収納室１８ａの最下部付近から保持可能な分のトナーを掬い取ることができる。トナー保持部２２ｆの内部に掬い取ったトナーは、トナー保持部２２ｆの内壁及びガイド部１８ａ２によって動きが制限されるため、トナー保持部２２ｆの回転方向の下流側に保持された状態で搬送される。搬送部材２２の回転に伴って搬送部材２２の自由端側の先端がガイド部１８ａ２を通過した後に、搬送部材２２及びトナー収納室１８ａの内壁の当接が解放される。

In Example 1, the evaluation results were derived under the conditions where the toner amount to be filled in the toner storage chamber 18a was 200 g and 50 g. However, both the toner supply from the toner storage chamber 18a to the developing chamber 18b was sufficient. The principle will be described below. First, as the conveying member 22 rotates, toner that can be held from the vicinity of the lowermost portion of the toner storage chamber 18a can be scooped into the toner holding portion 22f. The toner scooped inside the toner holding portion 22f is transported while being held on the downstream side in the rotation direction of the toner holding portion 22f because the movement is restricted by the inner wall of the toner holding portion 22f and the guide portion 18a2. . As the transport member 22 rotates, the free end of the transport member 22 passes through the guide portion 18a2, and the contact between the transport member 22 and the inner wall of the toner storage chamber 18a is released.

  Then, the conveying member 22 is released from the state of being deformed by the guide portion 18a2, and is restored to the natural state (original shape) by its own elastic restoring force. The toner holding portion 22f quickly accelerates due to the shape change in the restoring direction of the conveying member 22. However, the toner in the toner holding portion 22f is strongly pressed against and strongly held by the inner wall of the toner holding portion 22f. Don't go out.

  When the conveying member 22 is separated from the boundary portion q, the conveying member 22 is rotated to a position where it can come into contact with the periphery of the opening 18c due to its elastic recovery. Therefore, at the moment when the conveying member 22 is separated from the boundary portion q, the conveying member 22 abuts against the partition wall 26 around the opening 18c with its elastic force.

  At this time, the toner holding portion 22f decelerates rapidly, but the toner in the toner holding portion 22f is released out of the toner holding portion 22f in the moving direction immediately before the contact of the toner holding portion 22f, that is, according to inertia. . As shown in FIG. 4B, when the conveying member 22 and the partition wall 26 contact each other, the first direction J perpendicular to the plane of the opening 18c and the second direction indicating the moving direction immediately before the contact of the toner holding portion 22f. K is almost parallel. Thereby, the toner released out of the toner holding portion 22f efficiently enters the developing chamber 18b through the opening 18c.

  Thus, the toner can be efficiently and satisfactorily conveyed against the gravity from the toner storage chamber 18a to the developing chamber 18b with a simpler configuration that can easily cope with downsizing. Further, regardless of the amount of toner in the toner storage chamber 18a, a constant toner amount can be held in the toner holding portion 22f from the bottom of the toner storage chamber 18a. Therefore, regardless of the amount of toner in the toner storage chamber 18a, the toner can be efficiently and satisfactorily conveyed from the toner storage chamber 18a to the developing chamber 18b against gravity.

  In Example 2, the evaluation results were derived under the conditions where the toner amount to be filled in the toner storage chamber 18a was 200 g and 50 g. However, both the toner supply from the toner storage chamber 18a to the developing chamber 18b was sufficient. The principle will be described below. First, as the conveying member 22 rotates, toner that can be held from the vicinity of the lowermost portion of the toner storage chamber 18a can be scooped into the toner holding portion 22f. The toner scooped into the toner holding portion 22f is transported while being held on the downstream side in the rotation direction of the toner holding portion 22f because the movement is restricted by the inner wall of the toner holding portion 22f and the guide portion 18a2. The toner that has accumulated on the sheet portion 22a closer to the conveyance support shaft 22b than the toner holding portion 22f falls in the direction of arrow P in FIG. The process up to this point is the same as in the first embodiment.

  Until just before the conveying member 22 and the partition wall 26 come into contact, the toner holding portion 22f is quickly accelerated by the shape change in the restoring direction of the conveying member 22. However, the toner inside the toner holding portion 22f is strongly pressed against and strongly held by the inner wall of the toner holding portion 22f, and does not go out of the toner holding portion 22f.

  On the other hand, when the conveyance member 22 and the partition wall 26 come into contact with each other, the closest contact portion 22a1 closest to the rotation center of the conveyance member 22 to the toner holding portion 22f among the sheet portions 22a in contact with the partition wall protrusions 26a is the closest contact. The region 22a1 is used as a fulcrum to deform downstream in the rotational direction. Then, the toner inside the toner holding unit 22f is vigorously discharged out of the toner holding unit 22f in the moving direction immediately before the contact of the toner holding unit 22f.

  As shown in FIG. 4B, when the conveying member 22 and the partition wall 26 are in contact with each other, the first direction J perpendicular to the plane of the opening 18c and the second direction K in the moving direction immediately before the contact with the toner holding portion 22f. Are almost parallel. Thereby, the toner released out of the toner holding portion 22f efficiently enters the developing chamber 18b through the opening 18c.

  Thus, the toner can be efficiently and satisfactorily conveyed against the gravity from the toner storage chamber 18a to the developing chamber 18b with a simpler configuration that can easily cope with downsizing. Further, regardless of the toner amount inside the toner storage chamber 18a, a constant toner amount can be held in the toner holding portion 22f from the lowermost portion of the toner storage chamber 18a. Therefore, regardless of the amount of toner inside the toner storage chamber 18a, the toner can be efficiently and satisfactorily conveyed from the toner storage chamber 18a to the developing chamber 18b against gravity.

  In the first comparative example, the evaluation results were derived under the conditions where the toner amount to be filled in the toner storage chamber 18a was 200 g and 50 g, but the toner supply from the toner storage chamber 18a to the developing chamber 18b was not sufficient. The principle will be described below. The angle θ formed between the conveying member 22 and the floor side inner wall portion 18a1 near the lowermost portion of the toner storage chamber 18a is 60 °, and the contact angle θ is large. The toner near the lowermost portion of the chamber 18a can be lifted up to the guide portion 18a2. Of the toner lifted by the conveying member 22, the movement of the toner on the free end side of the conveying member 22 is restricted by the conveying member 22 and the guide portion 18a2, so that the toner is held on the downstream side in the rotation direction of the conveying member 22. Be transported.

  As the transport member 22 rotates, the free end of the transport member 22 passes through the guide portion 18a2, and then the contact of the transport member 22 with the inner wall of the toner storage chamber 18a is released. Then, the conveying member 22 is released from the state of being deformed by the guide portion 18a2, and is restored to the natural state (original shape) by its own elastic restoring force. Due to the shape change of the conveying member 22 in the restoring direction, the toner carried and conveyed on the conveying member 22 flies against the gravity toward the opening 18c.

  When the conveying member 22 is separated from the boundary portion q, the conveying member 22 is rotated to a position where it can come into contact with the periphery of the opening 18c due to its elastic recovery. Therefore, at the moment when the conveying member 22 is separated from the boundary portion q, the conveying member 22 hits the periphery of the opening 18c with its elastic force. Thereby, the toner can fly to the opening 18c.

  However, among the toners lifted by the conveying member 22 until the conveying member 22 moves away from the boundary portion q and hits the periphery of the opening 18c, the toner on the rotation center side of the conveying member 22 is in FIG. Drops in the direction of arrow P. Further, among the toner lifted by the conveying member 22, most of the toner on the free end side of the conveying member 22 is pushed out by centrifugal force because the toner cannot be held on the conveying member 22, and FIG. It falls in the direction of arrow Q inside.

  That is, there is nothing other than the conveying member 22 that restricts the movement of the toner until the conveying member 22 moves away from the boundary portion q and hits the periphery of the opening 18c. For this reason, the toner on the transport member 22 is likely to dissipate outside the opening 18c, and it is difficult to efficiently transport the toner from the toner storage chamber 18a to the developing chamber 18b against gravity.

  Here, of the toner lifted up to the guide portion 18a2 by the transport member 22, the proportion of the toner that can be transported to the opening portion 18c is substantially constant. Accordingly, when the amount of toner in the toner storage chamber 18a is small, the amount of toner that the transport member 22 lifts to the guide portion 18a2 is reduced, so that the toner is efficiently transported from the toner storage chamber 18a to the development chamber 18b against gravity. That is especially difficult.

  In the second comparative example, the evaluation result was derived under the condition that the toner amount to be filled in the toner storage chamber 18a is 200 g and 50 g. However, both the toner supply from the toner storage chamber 18a to the developing chamber 18b is very insufficient. The principle will be described below. The angle θ formed by the conveying member 22 and the floor-side inner wall 18a1 near the lowermost portion of the toner storage chamber 18a is 45 °, and the contact angle θ is small. A large amount of toner near the lowermost portion of the chamber 18a cannot be lifted up to the guide portion 18a2. Of the toner lifted by the conveying member 22, the movement of the toner on the free end side of the conveying member 22 is restricted by the conveying member 22 and the guide portion 18a2, so that the toner is held downstream in the rotation direction of the conveying member 22. It is conveyed by. However, since the angle θ formed by the conveying member 22 and the guide portion 18a2 is 23 ° and the contact angle θ is small, it is not possible to convey all the toner on the free end side of the conveying member 22.

   As the transport member 22 rotates, the free end of the transport member 22 passes through the guide portion 18a2, and then the contact of the transport member 22 with the inner wall of the toner storage chamber 18a is released. Then, the conveying member 22 is released from the state of being deformed by the guide portion 18a2, and is restored to the natural state (original shape) by its own elastic restoring force.

  However, when the free end of the conveying member 22 moves away from the boundary portion q, it can rotate only to a position that is not in contact with the periphery of the opening 18c even if it is restored by its elasticity. In other words, the toner on the free end side of the conveying member 22 cannot fly to the opening 18c by using the elastic force of the conveying member 22. The toner remaining on the free end side of the conveying member 22 is also rubbed and dropped by the partition wall 26 at the lower end of the opening 18c.

  Thus, in the second comparative example, the toner on the free end side of the conveying member 22 cannot be caused to fly to the opening 18c by using the elastic force of the conveying member 22. Further, the toner remaining on the free end side of the conveying member 22 is rubbed and dropped by the partition wall 26 at the lower end of the opening 18c, so that the toner is efficiently moved from the toner storage chamber 18a to the developing chamber 18b against gravity. It is difficult to carry.

  In the third comparative example, the evaluation results were derived under the conditions where the toner amount to be filled in the toner storage chamber 18a was 200 g and 50 g, but the toner supply from the toner storage chamber 18a to the developing chamber 18b was not sufficient. The principle will be described below. The angle θ formed between the conveying member 22 and the floor side inner wall portion 18a1 near the lowermost portion of the toner storage chamber 18a is 60 °, and the contact angle θ is large. The toner near the lowermost portion of the chamber 18a can be lifted up to the guide portion 18a2.

  Of the toner lifted by the conveyance member 22, the movement of the toner on the free end side with respect to the conveyance member protrusion 22d is limited by the conveyance member protrusion 22d, the conveyance member 22, and the guide portion 18a2. It is conveyed while being held downstream in the direction.

   As the transport member 22 rotates, the free end of the transport member 22 passes through the guide portion 18a2, and then the contact of the transport member 22 with the inner wall of the toner storage chamber 18a is released. Then, the conveying member 22 is released from the state of being deformed by the guide portion 18a2, and is restored to the natural state (original shape) by its own elastic restoring force. Due to the shape change of the conveying member 22 in the restoring direction, the toner carried and conveyed on the conveying member 22 flies against the gravity toward the opening 18c.

  When the conveying member 22 is separated from the boundary portion q, the conveying member 22 is rotated to a position where it can come into contact with the periphery of the opening 18c due to its elastic recovery. Therefore, at the moment when the conveying member 22 is separated from the boundary portion q, the conveying member 22 hits the periphery of the opening 18c with its elastic force. Thereby, the toner can fly to the opening 18c.

  However, of the toner lifted by the conveying member 22 until the conveying member 22 moves away from the boundary q and hits the periphery of the opening 18c, the toner on the free end side of the conveying member protrusion 22d is transferred to the conveying member 22. The toner cannot be retained. For that reason, most of them are pushed outward by centrifugal force and fall.

  That is, there is nothing that restricts the movement of the toner other than the conveyance member 22 and the conveyance member protrusion 22d until the conveyance member 22 moves away from the boundary portion q and hits the periphery of the opening 18c. For this reason, the toner on the transport member 22 is likely to dissipate outside the opening 18c, and it is difficult to efficiently transport the toner from the toner storage chamber 18a to the developing chamber 18b against gravity.

  Here, the ratio of the toner lifted up to the guide portion 18a2 by the transport member 22 to the opening portion 18c is substantially constant. Therefore, when the amount of toner in the toner storage chamber 18a is small, the amount of toner that the transport member 22 lifts to the guide portion 18a2 decreases, and therefore it is possible to efficiently transport toner from the toner storage chamber 18a to the development chamber 18b against gravity. Especially difficult.

  FIG. 14 is a cross-sectional view illustrating a configuration of the developing unit 304 according to the third embodiment. Among the configurations of the developing unit 304 of the third embodiment, the same configurations and effects as those of the developing unit 4 of the first embodiment are denoted by the same reference numerals and description thereof is omitted as appropriate. Since the third embodiment can be applied to the same image forming apparatus as that of the first embodiment, the description of the image forming apparatus is omitted. The developing unit 304 of the third embodiment is different from the developing unit 4 of the first embodiment in that, in the developing unit 304 of the third embodiment, the guide portion 18a2 is formed in a convex shape in the inner direction of the toner storage chamber 18a. .

  As shown in FIG. 14, in the developing unit 304, the guide portion is provided in the toner storage chamber 18 a on the upstream side in the rotational direction of the opening 18 c formed in the partition wall 26 in the rotational direction G of the conveying member 22. 18a2 is provided. Here, the guide portion 18 a 2 functions as a deforming portion that comes into contact with the conveying member 22 in order to deform the sheet portion 22 a against the elasticity of the sheet portion 22 a as the conveying member 22 rotates. In particular, the guide portion 18 a 2 is formed so that the distance between the guide portion 18 a 2 and the rotation center of the conveyance member 22 gradually decreases in the rotation direction G of the conveyance member 22.

  Further, in the rotational direction G of the conveying member 22, a restoring portion 18a4 is formed on the downstream side of the guide portion 18a2 and on the upstream side of the opening portion 18c so that the toner holding portion 22f on the free end side of the sheet portion 22a does not contact. ing. The restoring portion 18a4 is formed by a part of the inner wall of the toner storage chamber 18a. Further, the restoring portion 18a4 is provided further downstream in the rotational direction than the downstream end portion (hereinafter referred to as “boundary portion”) q of the guide portion 18a2 in the rotational direction G. Further, the restoring portion 18a4 is formed by providing a step 18a5 on the inner wall of the toner storage chamber 18a so that the distance from the rotation center of the conveying member 22 is increased. Here, the step 18a5 is set larger than the repose angle of the toner so that the toner falls. In the restoring portion 18a4, the free end of the transport member 22 does not contact the inner wall of the toner storage chamber 18a.

  After the conveying member 22 rotates and the free end of the conveying member 22 passes through the boundary portion q, the conveying member 22 and the inner wall (the restoring portion 18a4) of the toner storage chamber 18a are not in contact with each other. Thereby, the deformation of the sheet portion 22a is released. As described above, when the deformation of the elastic sheet portion 22a is released, an elastic restoring force is generated in the sheet portion 22a to return to the natural state before the deformation.

  The toner holding portion 22f quickly accelerates due to the shape change in the restoring direction of the conveying member 22, but the toner inside the toner holding portion 22f is strongly pressed against the inner wall of the toner holding portion 22f and strongly held. Do not go outside.

  When the conveying member 22 is separated from the boundary portion q, the conveying member 22 is rotated to a position where it can come into contact with the periphery of the opening 18c due to its elastic recovery. Therefore, at the moment when the conveying member 22 is separated from the boundary portion q, the conveying member 22 abuts against the partition wall 26 around the opening 18c with its elastic force.

  At this time, the toner holding portion 22f decelerates rapidly, but the toner inside the toner holding portion 22f is released to the outside of the toner holding portion 22f in the moving direction immediately before the contact of the toner holding portion 22f, that is, according to inertia. The As in Example 1, the following can be said. That is, when the conveying member 22 and the partition wall 26 are in contact with each other, the first direction J perpendicular to the plane along the opening 18c and the second direction K, which is the moving direction immediately before the contact with the toner holding portion 22f, are substantially parallel. This is the same as shown in FIG. Thereby, the toner released out of the toner holding portion 22f efficiently enters the developing chamber 18b through the opening 18c.

  Thus, the toner can be efficiently and satisfactorily conveyed against the gravity from the toner storage chamber 18a to the developing chamber 18b with a simpler configuration that can easily cope with downsizing. Further, regardless of the toner amount inside the toner storage chamber 18a, a constant toner amount can be held in the toner holding portion 22f from the lowermost portion of the toner storage chamber 18a. Therefore, regardless of the amount of toner in the toner storage chamber 18a, the toner can be efficiently and satisfactorily conveyed from the toner storage chamber 18a to the developing chamber 18b against gravity.

  As described above, according to the configuration of the third embodiment, the same effect as that of the first embodiment can be obtained. Further, the guide portion 18 a 2 is configured such that the boundary portion q is closest to the rotation center of the transport member 22. Furthermore, the guide portion 18a2 is formed such that the distance between the guide portion 18a2 and the rotation center of the conveyance member 22 gradually decreases as the conveyance member 22 advances in the rotation direction G. That is, the guide portion 18a2 is closer to the rotation center as it is closer to the boundary portion q. For this reason, when passing through the guide portion 18a2, the deformation of the sheet portion 22a gradually increases. Then, the deformation of the sheet portion 22a is instantaneously released at the boundary portion q. As a result, more toner than in the first embodiment can be supplied to the developing chamber 18b.

[Other Examples]
[Inner wall of toner storage room]
In the first to third embodiments, the conveyance member 22 is in contact with the guide portion 18a2 of the toner storage chamber 18a. However, the configuration is not limited thereto. For example, in the first embodiment, the present invention can be applied even when the conveying member 22 and the guide portion 18a2 are not in contact with each other. In the first exemplary embodiment, the conveying member 22 may be close to the floor-side inner wall 18a1 near the lowermost portion of the toner storage chamber 18a even if it is not in contact with the toner storage chamber 18a.

[Hole that can pass through the conveying member]
FIG. 15A is a plan view illustrating a modified example of the sheet portion 22 a of the conveying member 22. With reference to this Fig.15 (a), the modification of the sheet | seat part 22a is explained in full detail. In Examples 1 to 3, the example in which the hole is not formed in the sheet portion 22a of the conveying member 22 has been described, but the configuration is not limited to this. For example, as shown in FIG. 15A, a plurality of holes 22 g through which toner can pass may be formed in the sheet portion 22 a of the conveying member 22. When a large amount of toner is filled in the toner storage chamber 18a, the entire toner inside the toner storage chamber 18a must be transported by the rotation of the transport member 22 unless the sheet portion 22a of the transport member 22 has a hole. I must. In this case, a driving load for rotationally driving the conveying member 22 is increased, and a large powder pressure is continuously applied to the toner inside the toner storage chamber 18a, so that the toner is easily deteriorated.

  On the other hand, a hole is formed in the sheet portion 22a of the conveying member 22. When powder pressure is applied to the toner inside the toner storage chamber 18a by the rotation of the conveying member 22, the toner passes through the hole 22g and the powder pressure Can escape. In this case, the driving load for rotationally driving the conveying member 22 is reduced, and the toner in the toner storage chamber 18a is not applied with a large powder pressure, so that the toner is hardly deteriorated. Even in this case, sufficient toner can be held in the toner holding portion 22f at the tip of the conveying member 22, so that a sufficient amount of toner can be supplied from the toner storage chamber 18a to the developing chamber 18b.

  FIGS. 16A to 16D are cross-sectional views illustrating examples and modifications of the toner holding unit 22 f of the conveying member 22. As shown in FIG. 16A, in the first to third embodiments, the toner holding portion 22f is disposed at a position farthest from the rotation center of the conveying member 22, but the configuration is not necessarily limited thereto. That is, the toner holding portion 22f is set between the closest contact portion 22a1 closest to the conveyance member 22 and the portion farthest from the conveyance member 22 among the sheet portions 22a that are in contact with the partition wall protrusions 26a. is necessary. Further, it is necessary to satisfy that at least a part of the toner holding portion 22f and the opening portion 18c overlap each other. As long as these two are satisfied at the same time, the configuration is not limited to those of the first to third embodiments.

  First, in the first to third embodiments, the toner holding portion 22f is provided on the leading end side of the sheet portion 22a. However, the configuration is not necessarily limited thereto. That is, as illustrated in FIG. 16B, a part of the sheet portion 22 a may extend to a position farthest from the rotation center of the conveying member 22. In this case, when the conveyance member 22 comes into contact with the inner wall of the toner storage chamber 18a, the conveyance member 22 can be hardly caught by a part of the inner wall of the toner storage chamber 18a.

  In the first to third embodiments, the toner holding unit 22f is disposed upstream of the sheet unit 22a in the rotation direction. However, the configuration is not necessarily limited thereto. That is, if the upstream surface in the rotation direction of the conveying member 22 is formed in a concave shape, as shown in FIG. 16C, a part of the toner holding portion 22f is moved in the rotation direction from the sheet portion 22a. It may be disposed across the downstream side.

  Furthermore, in the first to third embodiments, the toner holding portion 22f is formed in a U-shape, but is not necessarily limited to this configuration. That is, as shown in FIG. 16D, the toner holding portion 22f may be formed in a U shape. In addition, any shape may be used as long as it is concave on the upstream side in the rotation direction of the conveying member 22.

  In the first exemplary embodiment, as illustrated in FIG. 4A, the toner holding portion 22f is arranged so as to partially overlap the opening portion 18c in the swinging direction of the concave portion 22f1, but the configuration is not necessarily limited thereto. For example, the entire opening 18c may be disposed so as to overlap the recess 22f1 of the toner holding unit 22f in the swinging direction of the recess 22f1. As a result, the toner inside the toner holding portion 22f is released from the entire opening 18c, and the amount of toner that can be supplied from the toner storage chamber 18a to the developing chamber 18b increases.

[Deformation of toner holding part toward downstream in rotation direction]
In the second embodiment, the following can be said when the conveying member 22 and the partition wall 26 come into contact with each other. That is, among the sheet portions 22a that are in contact with the partition wall projections 26a, the closest contact portion 22a1 to the toner holding portion 22f that is closest to the rotation center of the conveying member 22 rotates the sheet portion 22a with the closest contact portion 22a1 as a fulcrum. Deforms downstream in the direction. Then, the toner inside the toner holding unit 22f is vigorously discharged out of the toner holding unit 22f in the moving direction immediately before the contact of the toner holding unit 22f. In this way, any configuration may be used as long as the toner holding portion can be deformed downstream in the rotation direction.

  FIG. 16E is a cross-sectional view illustrating a configuration of a modified example of the conveying member 22 in the developing unit 404. As shown in FIG. 16E, a conveying member elastic protrusion 22e formed in a convex shape may be provided on the surface in the rotational direction of the sheet portion 22a of the first embodiment. The conveyance member elastic protrusion 22e of the conveyance member 22 is set so as to contact the partition wall 26. Also in this case, the portion from the conveying member elastic protrusion 22e to the toner holding portion 22f is deformed downstream in the rotation direction with the conveying member elastic protrusion 22e as a fulcrum. Then, the toner inside the toner holding unit 22f is vigorously discharged out of the toner holding unit 22f in the moving direction immediately before the contact of the toner holding unit 22f.

[There is a toner holding part only partly in the longitudinal direction]
In the first to third embodiments, an example in which the toner holding portion 22f is provided in the entire longitudinal direction is described. However, the configuration is not limited to this configuration. That is, the concave portion 22f1 may be formed only in a part of the sheet portion 22a in the longitudinal direction. For example, when the openings 18c are provided only at both longitudinal ends, as shown in FIG. 15B, the toner holding portion 22f may be disposed only in the vicinity of the longitudinal position where the openings 18c are located.

[The length from the rotation center of the conveying member to the outermost part changes in the longitudinal direction]
Moreover, in Examples 1-3, although the length from the rotation center of the conveyance member 22 to the outermost part gave the example which does not change with respect to a longitudinal direction, it is not limited to this structure. That is, the length from the rotation center of the sheet portion 22a to the edge portion in the rotation radius direction may be different depending on the longitudinal direction of the sheet portion 22a. For example, when the opening 18c is provided only at both longitudinal ends, the toner holding portion 22f may be disposed only in the vicinity of the longitudinal position where the opening 18c is located. In this case, if the toner inside the toner storage chamber 18a is moved to both longitudinal ends and then held by the toner holding portion 22f, the toner storage chamber 18a is transferred to the developing chamber 18b even when the toner inside the toner storage chamber 18a is low. A sufficient amount of toner can be supplied. As shown in FIG. 15C, the length from the rotation center to the outermost part of the conveying member 22 is set to be longer at both longitudinal ends than at the longitudinal center, so that the toner inside the toner storage chamber 18a is removed. Can be brought to the longitudinal ends.

[Developing chamber stirring member]
In the first to third embodiments, the developing chamber 18b is not provided with the stirring member or the conveying member 22, but is not limited to this configuration. For example, the stirring member or the conveying member 22 may be disposed at a position close to the supply roller 20 and a position directly below the vertical direction. Further, the stirring member or the conveying member 22 may be disposed at a position close to the supply roller 20 and at a position just beside it. In this case, the amount of toner supplied to the supply roller 20 can be increased by using the stirring member or the conveyance member 22. The present invention can be similarly applied to a developing chamber provided with such a stirring member or conveying member 22.

[Process cartridge type]
In the first to third embodiments, the developing unit 4 and the photosensitive unit 13 are integrally formed into a cartridge, and the process cartridge 7 that is detachable from the image forming apparatus 100 is formed. However, the present invention is not limited to this configuration. Absent. That is, the present invention similarly applies to an image forming apparatus having a configuration in which the photosensitive drum 1 is fixedly disposed on the image forming apparatus 100 and only the developing unit 4 is replaced as a cartridge (developing cartridge) that is detachable from the image forming apparatus 100. Can be applied. Alternatively, the present invention can be similarly applied to an image forming apparatus configured to fix the developing unit 4 to the image forming apparatus 100 and supply toner to the developing unit 4. A configuration similar to this is not limited to the embodiment of the present invention.

  As described above, according to the developer conveying device 4A of the first to third embodiments, the conveying member 22 is formed on the surface in the rotational direction on the leading end side of the sheet portion 22a and can hold the developer. Have Accordingly, the recess 22f1 scoops up the developer, and the developer is conveyed to the developing chamber 18b through the opening 18c. As a result, the developer is efficiently supplied from the toner storage chamber 18a to the development chamber 18b regardless of the amount of the developer inside the toner storage chamber 18a. In particular, even when a solid image having a high printing rate is continuously printed, the developer is efficiently supplied from the toner storage chamber 18a to the developing chamber 18b at a speed at which a solid image without density unevenness can be printed.

  Further, the sheet portion 22a fixed to the transport support shaft 22b has elasticity. Accordingly, the sheet portion 22a can be freely deformed inside the toner storage chamber 18a. As a result, the configuration of the developer conveying device 4a can be simplified and downsized.

  According to the developer transport device 4A of the second embodiment, the partition wall protrusion 26a is disposed on the lower side of the opening 18c in the partition wall 26 above the transport support shaft 22b. Accordingly, when the conveying member 22 rotates and the sheet portion 22a comes into contact with the partition wall projection 26a, the sheet portion 22a swings while bending with the contact point of the sheet portion 22a and the partition wall projection 26a as a fulcrum. 22f1 swings. As a result, the developer inside the recess 22f1 is vigorously ejected to the opening 18c.

  According to the developer conveying device 4A of Example 2, the sheet portion 22a contacts the partition wall projection 26a, and the sheet portion 22a and the recess 22f1 are deformed between the partition wall projection 26a and the conveyance support shaft 22b. pass. As a result, even in an area where the conveying member 22 does not draw up the developer, the developer is well stirred by utilizing the bending of the sheet portion 22a and the concave portion 22f1.

  According to the developer conveying device 4A of the first to third embodiments, the second direction K in which the recess 22f1 swings and the first direction J perpendicular to the surface along the opening 18c are substantially parallel. As a result, the splash of developer flying from the recess 22f1 can surely pass through the opening 18c of the partition wall 26.

  According to the developer conveying device 4A of the first to third embodiments, when the conveying member 22 rotates, the sheet portion 22a is deformed while being in contact with the guide portion 18a2, and is restored while being in contact with the restoring portion 18a4. Therefore, the restoring force for returning the sheet portion 22a from the deformed state to the natural state is utilized, and the developer scooped up in the concave portion 22f1 vigorously passes through the upper opening portion 18c against the gravity and passes through the developing chamber. 18b.

4a Developer transport device 18a Toner storage chamber (developer storage chamber)
18b Development chamber (adjacent chamber)
18c Opening 22a Sheet part (plate-like part)
22b Transport support shaft (rotary shaft)
22f Developer holding part 22f1 Concave part

Claims (12)

A developer transport device comprising: a developer container for containing a developer; and a transport member that is rotatably disposed inside the developer container and capable of transporting the developer,
The developer container includes a developer storage chamber that stores a developer, an adjacent chamber that is provided vertically below the developer storage chamber and is adjacent to the developer storage chamber, the developer storage chamber, and the adjacent An opening formed through a partition wall that partitions the chamber,
The conveying member is disposed below the opening and has a rotating shaft that is rotatable within the developer storage chamber, and a base plate that has a base end fixed to the rotating shaft and extends in a plate shape and has elasticity. And a developer holding part having a recess formed on the surface in the rotational direction on the tip side of the plate-like part and having a recess capable of holding the developer,
When the concave portion and the opening are in positions facing each other, projecting the concave portion in parallel with the moving direction, at least partially overlaps the opening,
After the conveyance member rotates and the concave portion holds the developer, the plate-like portion abuts against the developer container contact portion provided on the partition wall, whereby the plate-like portion and the developer container contact portion The concave portion is swung toward the opening portion while being decelerated with the contact point as a fulcrum, and the developer held in the concave portion receives a circumferential force due to inertial force and is discharged from the concave portion, and the opening A developer transporting device, wherein the developer transporting device is transported to the adjacent chamber through a section. 2. The developer conveying device according to claim 1, wherein the developer container contact portion is a protrusion disposed on a lower side of the opening in the partition wall above the rotation shaft. The dimension between the developer container contact portion and the rotating shaft can pass through the plate-like portion and the developer holding portion while elastically deforming when the plate-like portion contacts the developer container contact portion. The developer conveying device according to claim 1 , wherein the developer conveying device is set to have various dimensions. A first direction perpendicular to the surface along the opening and a second direction in which the concave portion swings when the plate-like portion contacts the developer container contact portion are substantially parallel to each other. developer conveying device according to any one of claims 1 to 3. The developer storage chamber is
A deformation portion that deforms the transport member by increasing a reaction force applied to the transport member in response to an increase in contact force associated with rotation of the transport member;
A restoring unit that reduces a reaction force applied to the transport member in response to a decrease in contact force accompanying rotation of the transport member, and restores the transport member;
A boundary between the deforming part and the restoring part,
The developer conveying device according to claim 1, wherein the boundary portion is provided below a lower end of the opening.   The developer conveying device according to claim 1, wherein a hole through which the developer can pass is formed in the plate-like portion.   7. The developer conveying device according to claim 1, wherein the entire opening portion overlaps the recess portion in the swinging direction of the recess portion.   The developer conveying device according to claim 1, wherein the concave portion is formed only in a part of the plate-like portion in the longitudinal direction.   9. The length from the rotation center of the plate-like portion to the edge in the radial direction of rotation differs according to the longitudinal direction of the plate-like portion. 9. Developer transport device.   The uppermost part of the recessed part is located above the lowermost part of the opening part when the recessed part is opposed to the opening part. Developer transport device. A developer carrying member carrying the developer;
A developer conveying device according to any one of claims 1 to 10,
A developing device comprising: An image carrier;
The developing device according to claim 11 for developing an electrostatic image formed on the image carrier;
A process cartridge comprising:

Images