JP6019877B2 - Stirring screw, developing unit, and image forming apparatus - Google Patents

Description

  The present invention relates to a stirring screw, a developing unit, and an image forming apparatus.

  In general, an electrophotographic image forming apparatus (printer, copying machine, facsimile, etc.) forms an electrostatic latent image by irradiating (exposing) laser light based on image data to a charged photoreceptor. Then, by attaching toner to the formed electrostatic latent image, the electrostatic latent image is visualized to form a toner image. Next, the toner image is transferred directly or indirectly to a sheet, and then heated and pressed to fix it, thereby forming an image on the sheet.

  The developing method for forming a toner image on a photoreceptor includes a one-component developing method using only toner as a main component of the developer and a two-component developer using a two-component developer consisting of a mixture of toner and carrier as the main component of the developer. There is a development method. Usually, in a two-component developing system developing device, in order to obtain a stable image, it is necessary to make the toner density and the developer amount uniform in the longitudinal direction of the developing device and to give a sufficient charge amount to the toner. . For this reason, in the conventional two-component developing type developing device, the screw-like developer conveying member is rotated to convey the toner and the carrier in the longitudinal direction of the developing device while stirring.

  As a screw-shaped developer conveying member that stirs the toner and the carrier, for example, various developer conveying members have been developed as shown in Patent Documents 1 to 5.

  In the developer transport device disclosed in Patent Document 1, paddles are provided in the radial direction on the outer periphery of the main body of a screw-shaped developer transport member disposed in the developer accommodating portion for the purpose of stirring. In Patent Document 1, the screw-like developer conveying member is provided so that the conveying directions are opposite to each other, and circulates and conveys the developer while being agitated by rotation. Further, the screw-like developer conveying member shown in Patent Document 2 is provided with protrusions such as blades from the outer periphery of the screw-like developer conveying member main body for the purpose of stirring, as in Patent Document 1.

  Further, the developer conveying member provided in the developing device of Patent Document 3 has another spiral-shaped portion inside a hollow member having a spiral-shaped portion on the outer peripheral surface. Furthermore, in the developer conveying member shown in Patent Document 4, a linear stirring member parallel to the rotation axis is provided outside the screw so as to be rotatable separately from the screw. Further, the developer conveying member provided in the developing device of Patent Document 5 has a feed screw-like wing body, and a mesh-like screen member is attached between the wing bodies.

JP 2009-109966 A JP 2006-337817 A JP 2004-226745 A JP 2004-205535 A JP-A-10-63081

  In these developer transport members of Patent Document 1 and Patent Document 2, since paddles and blades are formed against the rotational direction of the screw-shaped portion, the rotational torque of the developer transport member becomes a high load, There is a problem that the stirring performance cannot be improved.

  Further, in the configurations of Patent Document 3 and Patent Document 4, since the developer that is powder does not have a fluid-like viscosity, it only stirs a part of the region outside the screw. Therefore, there is no effect of stirring the inside of the screw.

  Furthermore, in the configuration of Patent Document 5, when the mesh of the mesh member arranged on the screw surface is close, it can be regarded as a paddle that closes the screw surface, so that the stirring performance is reduced. It is also clear that the wire applies shear stress to the surrounding powder and the powder is agitated by the generated speed difference. Therefore, it can be said that the stirring performance of Patent Document 5 depends on the degree of mesh density. Further, in this configuration, the vertical wire (in the direction orthogonal to the rotation axis) also acts as a resistance in the developer conveyance direction (the axial direction of the rotation shaft portion 91), so that the conveyance amount is reduced. Unavoidable. Furthermore, since the mesh member of Patent Document 5 has a structure in which the metals at the intersecting portions are rubbed, there is a problem that the possibility of disconnection is high.

  As described above, none of the configurations of the conventional developer conveying members shown in Patent Documents 1 to 5 can convey the developer with effective stirring.

  SUMMARY An advantage of some aspects of the invention is that it provides a stirring screw, a developing unit, and an image forming apparatus that can suitably stir a developer without reducing the transport amount.

One aspect of the stirring screw of the present invention is a stirring screw that is rotatably supported in a developer container containing a developer and stirs the developer. The stirring screw is formed in a screw shape around a rotation axis, and A blade member that conveys the agent in the direction of the rotation axis while stirring the agent, and a wire member that spans between the blades facing each other in the direction of the rotation axis of the blade member, and the line member extends in the direction of the rotation axis. a configuration that is disposed under tension so that the straight line between opposing the vane.

  One aspect of the developing unit of the present invention employs a configuration having the stirring screw having the above-described configuration and a developing container that rotatably supports the stirring screw inside the developer. One embodiment of the image forming apparatus of the present invention employs a configuration including the stirring screw having the above-described configuration.

  According to the present invention, with respect to the developer conveyed along the axial direction while being agitated by the rotation of the blade member, the linear member acts on the shear stress, finely pulverizes and agitates the developer. The region that translates in the axial direction in the state of a powder lump can be reduced. Therefore, the developer can be suitably stirred and transported without reducing the transport amount.

The figure which shows schematically the whole structure of an image forming apparatus provided with the stirring screw which concerns on embodiment of this invention. The figure which shows the principal part of the control system of an image forming apparatus provided with the stirring screw The figure which uses for description of the developing unit in an image forming apparatus provided with the stirring screw The perspective view which shows the principal part of the stirring screw Front view of the stirring screw Cross section of the stirring screw FIG. 7 is a partial cross-sectional view taken along line AA in FIG. 6. The figure which shows the positional relationship of the wire member of the stirring screw which concerns on embodiment of this invention. Diagram for explaining the state of the developer stirred by the stirring screw

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, an image forming apparatus including a stirring screw according to an embodiment of the present invention will be described.

<Overall configuration of image forming apparatus>
FIG. 1 is a diagram schematically illustrating an overall configuration of an image forming apparatus 1 including a stirring screw according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a main part of a control system of the image forming apparatus 1 according to the embodiment.

  An image forming apparatus 1 shown in FIGS. 1 and 2 is an intermediate transfer type color image forming apparatus using electrophotographic process technology. That is, the image forming apparatus 1 transfers the toner images of C (cyan), M (magenta), Y (yellow), and K (black) formed on the photosensitive drum 413 to the intermediate transfer belt 421 (primary transfer). Then, after superposing four color toner images on the intermediate transfer belt 421, the toner images are transferred to the paper S (secondary transfer) to form an image.

  In the image forming apparatus 1, the photosensitive drums 413 corresponding to the four colors of CMYK are arranged in series in the running direction of the intermediate transfer belt 421, and the respective color toner images are sequentially transferred to the intermediate transfer belt 421 in one procedure. Tandem system is adopted.

  As shown in FIGS. 1 and 2, the image forming apparatus 1 includes an image reading unit 10, an operation display unit 20, an image processing unit 30, an image forming unit 40, a paper transport unit 50, a fixing unit 60, and a control unit 100. .

  The control unit 100 includes a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, and the like. The CPU 101 reads a program corresponding to the processing content from the ROM 102 and develops it in the RAM 103, and centrally controls the operation of each block of the image forming apparatus 1 in cooperation with the developed program. At this time, various data stored in the storage unit 72 is referred to. The storage unit 72 includes, for example, a nonvolatile semiconductor memory (so-called flash memory) or a hard disk drive.

  The control unit 100 transmits and receives various data to and from an external device (for example, a personal computer) connected to a communication network such as a LAN (Local Area Network) or a WAN (Wide Area Network) via the communication unit 71. Do. For example, the control unit 100 receives image data transmitted from an external device, and forms an image on the paper S based on the image data (input image data). The communication unit 71 is composed of a communication control card such as a LAN card, for example.

  The image reading unit 10 includes an automatic document feeder 11 called an ADF (Auto Document Feeder), a document image scanning device 12 (scanner), and the like.

  The automatic document feeder 11 transports the document D placed on the document tray by a transport mechanism and sends it out to the document image scanning device 12. The automatic document feeder 11 can continuously read images (including both sides) of a large number of documents D placed on a document tray all at once.

  The document image scanning device 12 optically scans a document conveyed on the contact glass from the automatic document feeder 11 or a document placed on the contact glass, and reflects light from the document to a CCD (Charge Coupled Device). ) An image is formed on the light receiving surface of the sensor 12a, and an original image is read. The image reading unit 10 generates input image data based on the reading result by the document image scanning device 12. The input image data is subjected to predetermined image processing in the image processing unit 30.

  The operation display unit 20 is configured by, for example, a liquid crystal display (LCD) with a touch panel, and functions as a display unit 21 and an operation unit 22. The display unit 21 displays various operation screens, an image status display, an operation status of each function, and the like in accordance with a display control signal input from the control unit 100. The operation unit 22 includes various operation keys such as a numeric keypad and a start key, receives various input operations by the user, and outputs an operation signal to the control unit 100.

  The image processing unit 30 includes a circuit that performs digital image processing on input image data according to initial settings or user settings. For example, the image processing unit 30 performs gradation correction based on the gradation correction data (gradation correction table) under the control of the control unit 100. Further, the image processing unit 30 performs various correction processes such as color correction and shading correction, a compression process, and the like on the input image data in addition to the gradation correction. The image forming unit 40 is controlled based on the image data subjected to these processes.

  The image forming unit 40 includes image forming units 41Y, 41M, 41C, and 41K, and an intermediate transfer unit for forming an image using each color toner of Y component, M component, C component, and K component based on input image data. 42 etc. are provided.

  The Y component, M component, C component, and K component image forming units 41Y, 41M, 41C, and 41K have the same configuration. For convenience of illustration and explanation, common constituent elements are denoted by the same reference numerals, and Y, M, C, or K are added to the reference numerals when distinguished from each other. In FIG. 2, only the components of the Y-component image forming unit 41Y are denoted by reference numerals, and the constituent elements of the other image forming units 41M, 41C, and 41K are omitted.

  The image forming unit 41 includes an exposure device 411, a developing device 412, a photosensitive drum 413, a charging device 414, a drum cleaning device 415, and the like.

  The photosensitive drum 413 has an undercoat layer (UCL) and a charge generation layer (CGL) on the peripheral surface of an aluminum conductive cylinder (aluminum tube) having a drum diameter of 80 mm, for example. ), A negatively charged organic photoconductor (OPC) in which a charge transport layer (CTL) is sequentially stacked.

  The charge generation layer is made of an organic semiconductor in which a charge generation material (for example, phthalocyanine pigment) is dispersed in a resin binder (for example, polycarbonate), and generates a pair of positive charges and negative charges by exposure by the exposure device 411. The charge transport layer consists of a hole transport material (electron donating nitrogen-containing compound) dispersed in a resin binder (for example, polycarbonate resin), and transports positive charges generated in the charge generation layer to the surface of the charge transport layer. To do.

  The control unit 100 controls a drive current supplied to a drive motor (not shown) that rotates the photosensitive drum 413, so that the photosensitive drum 413 rotates at a constant peripheral speed.

  The charging device 414 uniformly charges the surface of the photoconductive drum 413 to a negative polarity.

  The exposure device 411 is composed of, for example, a semiconductor laser, and irradiates the photosensitive drum 413 with laser light corresponding to the image of each color component. A positive charge is generated in the charge generation layer of the photosensitive drum 413 and is transported to the surface of the charge transport layer, whereby the surface charge (negative charge) of the photosensitive drum 413 is neutralized. An electrostatic latent image of each color component is formed on the surface of the photosensitive drum 413 due to a potential difference from the surroundings.

  The developing device 412 contains a developer of each color component (for example, a two-component developer composed of a toner having a small particle diameter and a magnetic material), and causes the toner of each color component to adhere to the surface of the photosensitive drum 413. Thus, the electrostatic latent image is visualized to form a toner image. The detailed configuration of the developing device 412 will be described later.

  The drum cleaning device 415 includes a drum cleaning blade that is slidably contacted with the surface of the photosensitive drum 413, and removes transfer residual toner remaining on the surface of the photosensitive drum 413 after primary transfer.

  The intermediate transfer unit 42 includes an intermediate transfer belt 421 serving as an intermediate transfer member, a primary transfer roller 422, a secondary transfer roller 423, a driving roller 424, a driven roller 425, a belt cleaning device 426, and the like.

  The intermediate transfer belt 421 is an endless belt, and is stretched around a driving roller 424 and a driven roller 425. The intermediate transfer belt 421 travels at a constant speed in the direction of arrow A by the rotation of the driving roller 424. When the intermediate transfer belt 421 is pressed against the photosensitive drum 413 by the primary transfer roller 422, the toner images of the respective colors are sequentially superimposed on the intermediate transfer belt 421 and primarily transferred.

  When the sheet S passes through the transfer nip formed by the secondary transfer roller 423 being pressed against the intermediate transfer belt 421, the toner image primarily transferred to the intermediate transfer belt 421 is secondarily transferred to the sheet S. The

  The belt cleaning device 426 includes a belt cleaning blade that is slidably contacted with the surface of the intermediate transfer belt 421 and removes transfer residual toner remaining on the surface of the intermediate transfer belt 421 after the secondary transfer.

  The fixing unit 60 fixes the toner image on the sheet S by heating and pressing the conveyed sheet S at the fixing nip. The fixing unit 60 may be provided with an air separation unit that separates the sheet S from a fixing surface side member (for example, a fixing belt) or a back surface side support member (for example, a pressure roller) by blowing air.

The paper transport unit 50 includes a paper feed unit 51, a paper discharge unit 52, a transport roller unit 53, and the like.
In the three paper feed tray units 51a to 51c constituting the paper feed unit 51, paper S (standard paper, special paper) identified based on basis weight, size, or the like is stored for each preset type. .

  The conveyance roller unit 53 includes a plurality of conveyance roller pairs such as a registration roller pair 53a. The sheets S accommodated in the sheet feed tray units 51 a to 51 c are sent one by one from the top and conveyed to the image forming unit 40 by the conveying roller unit 53. At this time, the registration roller portion provided with the registration roller pair 53a corrects the inclination of the fed paper S and adjusts the conveyance timing.

  In the image forming unit 40, the toner image on the intermediate transfer belt 421 is secondarily transferred onto one side of the sheet S at a time, and the fixing unit 60 performs a fixing process. The sheet S on which the image has been formed is discharged out of the apparatus by a discharge unit 52 having a discharge roller 52a.

  FIG. 3 is a diagram for explaining the developing unit of the image forming apparatus including the stirring screw according to the embodiment of the present invention, and is a schematic diagram of the developing device. As shown in FIG. 3, the developing device 412 includes a developing unit 81 that forms a toner image on the photosensitive drum 413 and a toner replenishing unit 82 that replenishes the developing unit 81 with toner. Although not shown, the developing device 412 includes a carrier replenishing unit that replenishes the developing unit 81 with a carrier.

  The developing unit 81 includes a developing roller 811 (toner carrier), a conveyance roller 812 (developer carrier), stirring screws 90-1 and 90-2, a developer regulating member 815, a developer container 816, and a toner concentration detection sensor 83. Etc. That is, the developing unit 81 forms a toner image on the photosensitive drum 413 by a so-called hybrid developing method in which a two-component developing method and a one-component developing method are combined. The configuration of the developing unit 81 shown in FIG. 3 is an example, and a toner image is formed on the photosensitive drum 413 (see FIG. 1) using a two-component developer, that is, by a two-component developing method (including a hybrid developing method). As long as it forms, there is no particular limitation.

  The developing roller 811, the transport roller 812, and the stirring screws 90-1 and 90-2 are arranged in parallel, and rotate when the developing unit drive motor M <b> 1 (see FIG. 2) is driven by the control unit 100.

  In the developing container 816, a stirring screw 90-2, a stirring screw 90-1, a transporting roller 812, and a developing roller 811 are arranged in this order from the upstream side to the downstream side in FIG. Is done.

  The developer container 816 contains a developer and has a developer supply port 816a (substantially above the stirring screw 90-2 in FIG. 3) for supplying toner and carrier contained in the developer. The toner sent out from the toner supply unit 82 and the carrier sent out from the carrier supply unit (not shown) are supplied to the developing container 816 through the developer supply port 816a.

  Further, the developer container 816 has a developer discharge port 816b (substantially below the transport roller 812 in FIG. 3) for discharging the developer. The developer in the developer container 816 is periodically discharged through the developer discharge port 816b and recovered in a developer recovery container (not shown).

  The developing container 816 has stirring chambers 816c and 816d. The developer is agitated by the agitating screws 90-1 and 90-2 that are rotatably supported in the agitating chambers 816c and 816d, and conveyed to the developing roller 811 and the conveying roller 812 side.

  The stirring screws 90-1 and 90-2 have a screw-like blade member 92 (see FIG. 4) extending in the axial direction, and the respective ends are opposed to each other in the stirring chambers 816c and 816d. It arrange | positions so that a conveyance direction may be reverse.

  The agitating screws 90-1 and 90-2 are agitated and mixed while circulating and conveying the developer between the agitating chambers 816c and 816d.

  That is, the developer is conveyed while being stirred from one end side of the stirring screw 90-2 to the other end side by the rotating stirring screw 90-2. Next, the developer reaching the other end of the stirring screw 90-2 is stirred by the stirring screw 90-1 from the other end of the stirring screw 90-1 facing the other end side of the stirring screw 90-2. It is conveyed while being agitated at one end side.

  As described above, the agitating screws 90-1 and 90-2 rotating in the agitating chambers 816c and 816d frictionally contact the toner contained in the developer and the carrier, and are charged with opposite polarities. Here, it is assumed that the carrier is positively charged and the toner is negatively charged.

  The negatively charged toner adheres to the periphery of the positively charged carrier mainly by the electrical attraction force of both. The developer is supplied to the transport roller 812 in the process of being transported by the stirring screw 90-1. Further, the developer is stirred and mixed with new toner supplied from the toner replenishing unit 82 in the process of being conveyed by the stirring screw 90-2.

  The conveyance roller 812 is a so-called magnet roller having a magnet body 812a that is fixed so as not to rotate and a cylindrical conveyance sleeve 812b that is rotatably arranged around the magnet body 812a.

  A developer regulating member 815 is disposed substantially above the conveying sleeve 812b and is spaced apart from the conveying sleeve 812b by a predetermined distance. The developer regulating member 815 is a plate-like member formed of a magnetic material such as a stainless steel material and extends in parallel with the transport roller 812.

  The magnet body 812a has a plurality of magnetic poles (not shown) extending in the axial direction of the transport roller 812. A magnetic field (lines of magnetic force) for transporting the developer by the transport sleeve 812b is formed by the plurality of magnetic poles.

  The developer supplied to the conveying sleeve 812b rises along the magnetic field lines formed by the magnet body 812a and forms a so-called magnetic brush. Then, the developer is transported counterclockwise with the rotation of the transport sleeve 812b, and is regulated to a certain thickness by passing through the gap with the developer regulating member 815.

  The developing roller 811 is a conductive roller made of a metal such as aluminum. The developing roller 811 may be one in which a coating such as a polyester resin is formed on the outer peripheral surface of the conductive roller.

  By forming an electric field between the developing roller 811 and the transport roller 812, only the toner is detached from the developer transported by the transport sleeve 812b and supplied to the developing roller 811. The developing roller 811 supplies toner to the photoconductive drum 413 to visualize the electrostatic latent image on the photoconductive drum 413.

  The development unit 81 employs a trickle development system in which the developer is gradually replaced. That is, the developing unit 81 is configured to periodically replenish the developer (toner and carrier) from the developer replenishing port 816a and to discharge excess developer from the developer discharge port 816b (trickle mechanism). ). As the trickle mechanism, a known circulation overflow type or liquid level overflow type can be applied. As a result, the deteriorated carrier is replaced with a new carrier, so that the toner in the developing container 816 is always uniformly charged. Therefore, stable image quality is realized regardless of the number of prints and environmental changes.

  The toner concentration detection sensor 83 is a magnetic permeability sensor that detects the magnetic permeability of the developer in the developing container 816. The toner concentration detection sensor 83 is disposed so that the detector faces the opening provided at the bottom of the developing container 816 (substantially below the stirring screw 90-2 in FIG. 3). Based on the sensor output (output voltage indicating the magnetic permeability) of the toner concentration detection sensor 83, the toner concentration of the developer can be detected. The sensor output from the toner concentration detection sensor 83 is used when the control unit 100 determines whether or not toner replenishment is necessary.

  The toner replenishing unit 82 includes a toner box containing toner and a toner replenishing roller (both not shown). When the toner replenishing motor M2 (see FIG. 2) is driven by the control unit 100, the toner replenishing roller rotates. Accordingly, a predetermined amount of toner is supplied to the developing unit 81. The amount of toner replenished once by the toner replenishing unit 82 may be a constant amount or may be changed according to the toner consumption amount.

<Configuration of stirring screw>
The agitation screws 90-1 and 90-2 that are the characteristics of the image forming apparatus 1 according to the present embodiment will be described in detail. The stirring screw 90-2 is configured in the same manner as the stirring screw 90-1, and is arranged in the developing container 816 so that the spiral direction of the stirring screw 90-1 is reversed. Therefore, here, only the stirring screw 90-1 will be described using FIGS. 4 to 6, and details of the stirring screw 90-2 having the same configuration as the stirring screw 90-1 will be omitted.

  FIG. 4 is a plan view of the stirring screw, FIG. 5 is a perspective view showing a main part of the stirring screw, and FIG. 6 is a side view of the stirring screw.

  A stirring screw 90-1 shown in FIG. 4 includes a shaft portion 91, a blade member 92 formed around the shaft portion 91, and a rotation shaft between screw surfaces facing each other in the rotation axis direction of the shaft portion 91 in the blade member 92. And a line member 95 laid in parallel.

  The shaft portion 91 is rotatably supported at both ends 91a and 91b in the developing container 816 (see FIG. 3), specifically, in the stirring chamber 816c (816d).

  The blade member 92 is formed to protrude like a screw on the outer periphery of the shaft portion 91, and conveys the developer in the direction of the rotation axis of the shaft portion 91 while stirring the developer. The blade member 92 is formed together with the shaft portion 91, a resin member such as ABS resin (Acrylonitrile, Butadiene, Styrene copolymer synthetic resin), PC (Polycarbonate) resin, metal, or a combination of resin and metal.

  The shaft portion 91 is formed of a metal member in order to give strength, and the surrounding blade member 92 is formed of a resin member having a complex shape and excellent workability. The shaft portion 91 may have a configuration in which the outer periphery of a cylindrical metal member is covered with a resin member that is the same material as the blade member 92.

  As shown in FIGS. 4 to 6, the wire member 95 extends between blades (hereinafter also referred to as “screw surface portions”) 920 having blade surfaces (screw surfaces) 921 and 922 that face each other in the rotational axis direction in the blade member 92. Are installed side by side.

  The wire member 95 is formed of a fiber member made of a high-strength molecular material or a metal wire metal such as a piano wire, and has high durability performance. Here, the wire member 95 is formed of a high-strength carbon steel piano wire.

  The wire member 95 is a single continuous wire extending from the end surface of the one end portion 92a of the blade member 92 to the other end portion 92b. Here, the one end portion 92a and the other end portion 92b are formed in a flange shape, and the wire member 95 penetrates the plurality of blades 920 in the blade member 92 in the rotation axis direction, and the inner end surface of the one end portion 92a. It is constructed between the inner end face of the other end 92b.

  The linear members 95 that are parallel to the rotation axis are arranged so as to be in a straight line between the blades 920 that face each other in the direction of the rotation axis, specifically, between the screw surfaces 921 and 922 of the blades 920 and 920 that face each other. Has been. Here, the line member 95 is supported by the blade member 92 through the screw surfaces 921 and 922 of the plurality of blades 920 opposed in the rotation axis direction.

  7 is a partial cross-sectional view taken along line AA of FIG.

As shown in FIG. 7, in the blade 920 of the blade member 92, the thickness (t _max ) of the portion through which the wire member 95 is inserted is thicker in the rotation axis direction than the other portion (t) in the blade member 92. It has become. Here, the wire member 95 is inserted through a portion of the blade 920 that is thicker than the other portions, and is supported by being fixed. Further, the wire member 95 is disposed with tension so as to be a straight line between the screw surfaces 921 and 922. That is, the line member 95 is arranged with tension so as to be a straight line between the blades 920 opposed in the rotation axis direction. For example, the tension on the wire member 95 may be applied by forming the blade member 92 between the screw surfaces 921 and 922 of the blade member 92 by insert molding.

  A plurality of wire members 95 are arranged on the blade 920 of the blade member 92 in a direction orthogonal to the rotation axis.

  FIG. 8 is a view showing the positional relationship of the wire members in the stirring screw, and is a view of the stirring screw viewed in the axial direction.

  In the stirring screw 90-1, a plurality of wire members 95 are arranged on a plane passing through the rotation axis with a predetermined interval (a constant angle θ) around the rotation axis of the shaft portion 91.

Here, as shown in FIG. 8, a plurality of line members 95 are arranged on a plane passing through the rotation axis (a plane spaced about 90 degrees in the radial direction about the rotation axis) with respect to the blade member 92. Has been placed. Here, in the blade member 92, θ = constant plane in the rotational coordinate system, and four are arranged on the four planes θ = 90, 180, 270, and deg at 1.5 mm intervals in the radial direction. At this time, the diameter of the blade member 92 is 30 mm, the pitch of the blades facing in the rotation axis direction of the blade member 92 (screw pitch) l _S = 36 mm, and the wire member 95 is a piano wire with d _l = 0.2 mm. Good. In addition, you may make it the piano wire as the wire member 95 have the length which continues over the full length (screw length, for example, 300 mm) of the blade member 92.

  Next, the manufacturing method of this stirring screw 90-1 is demonstrated. In addition, since the stirring screw 90-2 is manufactured similarly, it abbreviate | omits about the manufacturing method of the stirring screw 90-2.

  First, a predetermined number of wire members 95 are prepared, and a jig for arranging the wire members 95 is provided in a resin mold for molding the blade member 92. And while arrange | positioning the wire member 95 to this jig, the metal columnar part with which the axial part 91 is provided is arrange | positioned. Thereafter, a screw-shaped blade member 92 is formed around the wire member 95 and the shaft portion 91 by pouring resin to be the blade member 92 into the mold.

  At this time, the wire member 95 is placed between the blades 920 of the formed blade member 92 when the stirring screw 90-1 is formed by applying a slight tension to the wire member 95 and placing the wire member 95 on the jig in the mold. It is fixed in a tensioned state. Thereby, when the stirring screw 90-1 is rotationally driven, the wire member 95 can be prevented from being cut by being repeatedly deformed by the developer to be stirred.

  As another method for manufacturing the stirring screw 90-1, a mold for forming the screw-like blade member 92 is prepared around the shaft 91, and the shaft 91 is disposed in the mold. Then pour the resin. Thereby, the screw main body in which the screw-like blade member 92 is formed around the rotation axis is formed. Then, in the blade member 92 after molding in the screw main body, a through hole penetrating in the axial direction is created in the blade 920 having a screw surface opposed in the axial direction, and the wire member 95 is passed therethrough. Then, the wire member 95 passed between the blades 920 is welded or bonded to both end portions 92a and 92b (or blades located at both ends) of the blade member 92 and the through holes, or further, a fastening member is used. The stirring screw 90-1 is manufactured by fixing. At this time, it is desirable that tension is applied between the blades 920 and the linear member 95 is arranged in a straight line.

The agitation screws 90-1 and 90-2 configured as described above are arranged in the agitation chambers 816c and 816d of the developing container 816 in the developing unit 81 of the image forming apparatus 1, and the two-component developer is supplied at a predetermined number of rotations. (For example, the number of revolutions n = 300 min ⁻¹ ) Thereby, the raw material agent can be mixed well and the toner lump in the developer can be pulverized. This state will be described with reference to FIG. Further, even when applied to the toner one-component system, old and new toner inside the stirring chambers 816c and 816d in the developing container 816 could be stirred evenly.

  FIG. 9 is a diagram for explaining the state of the developer stirred by the stirring screw according to the embodiment of the present invention. FIG. 9A is a top view partially showing the developer stirred by only the screw-like blade member, and FIG. 9B shows the developer stirred by the stirring screw according to the present embodiment. FIG.

  As shown in FIG. 9B, according to the stirring screws 90-1 and 90-2 of the present embodiment, the powder as a developer is compared with the case of stirring only with a screw-like blade member (FIG. 9A). It can be seen that the three-dimensional behavior is increased, and the region that translates in the axial direction is reduced, which indicates a good stirring state.

  In addition, the line member 95 can agitate the region inside the outer diameter of the blade member 92 (region on the central axis side). At this time, since the wire member 95 disposed between the screw surfaces has little resistance in the conveyance direction, for example, unlike the conventional stirring screw provided with the mesh member shown in Patent Document 5, the conveyance amount is significantly reduced. There is no.

  Further, when the stirring screws 90-1 and 90-2 are rotated around the rotation axis in the developing container 816, the linear member 95 stirs the developer in the developing container 816 by applying a shear stress. Thereby, in the developer, when there is a powder lump formed by the liquid crosslinking adhesion force or pressure, when the powder lump is positioned in the rotation direction with respect to the plurality of wire members 95, the wire member 95 The mass is agitated by applying shear stress in the rotational direction. That is, the developer lump is pulverized by the shear stress of the wire member 95 and conveyed in the direction of the rotation axis.

  In this way, the linear member 95 acts on the developer conveyed along the rotation axis direction while being agitated by the rotation of the blade member 92 to finely pulverize the developer lump. The region in which the developer is translated in the direction of the rotation axis in the state of a powder lump can be reduced by stirring.

  Therefore, the agitating screws 90-1 and 90-2 do not greatly increase the torque and greatly reduce the amount of developer as compared to a developer conveying member corresponding to a conventional agitating screw. Can be stirred and transported evenly. As a result, in the developer conveyed to the conveyance roller 812, the toner density can be made uniform.

  In addition, the wire member 95 is a single wire that continues from the end surface of the one end 92a to the end surface of the other end 92b that is spaced apart in the rotation axis direction in the blade member 92. That is, the wire member 95 between the blades 920 is formed by a part of the wire disposed along the rotation axis from the one end portion 92 a to the other end portion 92 b of the blade member 92.

  Thereby, when arrange | positioning a wire member over the full length of the blade member 92, it is not necessary to construct and arrange a wire member between the blades 920 of the blade member 92, and to each blade 920 in the blade member 92, The agitation screws 90-1 and 90-2 can be easily formed by inserting and supporting one wire rod in the direction of the rotation axis.

  Further, according to the present embodiment, a plurality of line members 95 are arranged on the blade member 92 on a plane passing through the rotation axis. For this reason, according to the stirring screw 90, the developer lump corresponding to the interval between the plurality of wire members 95 can be pulverized.

  By the way, in the conventional stirring screw shown to patent documents 1, 2, it is trying to add protrusions, such as a paddle, to a screw-shaped blade member and to improve stirring performance. In this configuration, there is a trade-off relationship between the point at which the drive torque of the stirring screw increases due to the protrusions and the point at which the developer transport amount decreases.

  On the other hand, in the stirring screw of the present embodiment, the line member 95 is disposed between the blades 920 of the screw-like blade member 92 to stir and mix the developer. For this reason, it is not necessary to attach a protrusion in consideration of the trade-off relationship as compared with the conventional case, and the developer can be reliably stirred and mixed with a simple configuration.

  Further, the plurality of line members 95 are arranged in parallel to each other on the blade member 92 side by side on a plane passing through the rotation axis. Thereby, when mass-producing the stirring screw 90-1 by arranging the wire member 95 in the mold for molding the blade member 92 and molding the blade member 95 with a resin material, the mold for molding the blade member 92. The number of mold divisions can be reduced. Specifically, as shown in FIG. 8, the molds B1 to B4 for forming the stirring screw 90-1 are radially outward from the formed stirring screw 90-1 (the direction indicated by the arrow C in FIG. 8). ), It can be divided by a plane on which the line members 95 are arranged. Thereby, when designing the molds of the stirring screws 90-1 and 90-2 (shown by broken lines B1 to B4 in FIG. 8), the number of divisions can be suppressed to a small number.

  Further, in the blade 920 of the blade member 92, the portion (screw surface portion) through which the wire member 95 is inserted is thicker than the other portions. For this reason, when mass-producing the screw main body having the shaft portion 91 and the blade member 92 by using a resin material, a portion corresponding to the blade 920 in the mold can be easily removed from the blade 920, and the durability performance of the mold. Can be improved.

  In the stirring screws 90-1 and 90-2 of the present embodiment, in the screw-like blade member 92, the line member 95 disposed between the blades 920 facing each other in the rotation axis direction is the entire length of the blade member 92. However, the present invention is not limited to this. For example, in the screw-like blade member 92, the line member 95 may be constructed in a position parallel to each other between the blades 920 arranged in the rotation axis direction.

  Further, in the stirring screws 90-1 and 90-2 of the present embodiment, the line member 95 disposed between the blades 920 opposed to each other in the rotation axis direction of the shaft portion 91 in the screw-like blade member 92 has a rotation shaft. Is not limited to this. For example, the wire member 95 may be configured to be spanned between the blades 920 so as to extend in a direction inclined with respect to the rotation axis.

  In the stirring screw 90 of the present embodiment, a plurality of line members 95 are arranged between the blades 920 of the blade members 92 on a plane passing through the rotation axis. The blade member 92 may be installed between the blades 920 at an arbitrary position in parallel with the rotation axis.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 81 Developing unit 90-1, 90-2 Agitating screw 91 Shaft part 92 Blade member 95 Wire member 100 Control part 411 Exposure apparatus 412 Developing apparatus 413 Photosensitive drum 811 Developing roller 812 Conveying roller 815 Developer regulating member 816 Developing Container 920 Blade 921, 922 Screw face 92a One end 92b Other end 816c, 816d Stirring chamber

Claims (11)

A stirring screw that is rotatably supported in a developer container that contains the developer and stirs the developer,
A blade member that is formed in a screw shape around the rotation axis and conveys the developer in the direction of the rotation axis while stirring the developer;
A wire member spanned between the blades facing each other in the rotational axis direction in the blade member;
Equipped with a,
The line member is arranged with tension so as to be a straight line between the blades opposed in the rotation axis direction,
Stir screw. The line member is parallel to the rotation axis.
The stirring screw according to claim 1. The wire member is inserted and supported by a plurality of blades arranged in the direction of the rotation axis in the blade member.
The stirring screw according to claim 1 or 2. The wire member is a single wire that continues from one end to the other end of the blade member that is spaced apart in the rotation axis direction.
The stirring screw according to claim 3. In the blade, the portion through which the wire member is inserted is thicker than other portions,
The stirring screw according to claim 3 or 4. A plurality of the line members are arranged in parallel with the rotation axis,
The stirring screw according to any one of claims 3 to 5. The plurality of line members are arranged in parallel to each other along the plane passing through the rotation axis, to the blade member.
The stirring screw according to claim 6. The plurality of line members are arranged in a row in the radial direction from the rotating shaft to the outer edge of the blade member on the blade member .
The stirring screw according to claim 7. The wire member is formed of resin or metal.
The stirring screw according to any one of claims 1 to 8 . A stirring screw according to any one of claims 1 to 9,
A developer container that rotatably supports the stirring screw inside the developer; and
Having
Development unit. Comprising the agitation screw according to any one of claims 1 to 9,
Image forming apparatus.