JP6652896B2 - Developing device, image forming unit and image forming device - Google Patents

Description

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

  The present applicant has already filed an application for an electrophotographic image forming apparatus for forming an image on various media (for example, see Patent Document 1). In such an image forming apparatus, the developer carried on the developer itself is brought into contact with the image carrier, and a voltage is applied to develop the electrostatic latent image on the image carrier.

Japanese Patent No. 4041456

  By the way, such an image forming apparatus is required to further improve the image quality.

  Therefore, it is desirable to provide a developing device, an image forming unit, and an image forming apparatus suitable for forming an excellent image.

A developing device according to an embodiment of the present invention includes a container that includes an opening provided on an inner surface and an upper portion and that can receive a developer and that stores the developer, a developer carrying member that carries the developer, and a container. A developer supply member that is stored and supplies the developer to the developer carrier, and a developer that is stored in the container and conveys the developer in a direction in which the developer supply member extends by moving and moves away from the opening. and agent conveying member, of the inner surface, provided on the surface facing the developer supplying member, to have a developing agent guide member for guiding the developer in a direction crossing the extending direction of the developing agent supplying member. Here, the developer located below the developer transport member in the container is guided toward the developer transport member and the opening along the developer guide member by rotation of the developer supply member.

  An image forming unit as one embodiment of the present invention includes the above-described developing device and an image carrier that carries a developer image developed by the developer carrier. Further, an image forming apparatus as one embodiment of the present invention includes the above image forming unit.

  In the developing device, the image forming unit, and the image forming apparatus as one embodiment of the present disclosure, the developer is transported in the container in the extending direction of the developer supply member by the developer transport member, and the developer guide member is provided. Accordingly, the developer supply member is guided in a direction intersecting with the extending direction of the developer supply member. For this reason, the fluidity of the developer inside the container is increased, and the developer is effectively circulated, so that the developer is prevented from staying or aggregating in a specific place.

  According to the developing device, the image forming unit, and the image forming apparatus as one embodiment of the present invention, since the developer is circulated in the container, the quality of the developer in the container hardly varies. Therefore, it is suitable for forming an excellent image. The effect of the present invention is not limited to this, and may be any of the effects described below.

FIG. 1 is a schematic diagram illustrating an overall configuration example of an image forming apparatus according to an embodiment of the present disclosure. FIG. 2 is a schematic diagram illustrating an internal configuration of the image forming unit illustrated in FIG. 1. FIG. 2 is another schematic diagram illustrating an internal configuration of the image forming unit illustrated in FIG. 1. FIG. 3B is a cross-sectional view illustrating a cross-sectional shape of the developer guide member illustrated in FIG. 3A. FIG. 2 is a block diagram illustrating an internal configuration of the image forming apparatus illustrated in FIG. 1. FIG. 9 is a schematic diagram illustrating a first print pattern in Experimental Examples 1 to 3. FIG. 9 is a schematic diagram illustrating a second print pattern in Experimental Examples 1 to 3.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following description is a specific example of the present invention, and the present invention is not limited to the following embodiments. Further, the present invention is not limited to the arrangement, dimensions, dimensional ratios, and the like of the components shown in the drawings. The description will be made in the following order.
1. One Embodiment (Developing Apparatus Provided with Developer Conveying Member and Developer Guide Member in Container Containing Developer, Image Forming Unit and Image Forming Apparatus Provided Therewith)
2. Experimental example 3 Other modifications

<1. One Embodiment>
[Configuration of Image Forming Apparatus]
FIG. 1 schematically illustrates an overall configuration example of an image forming apparatus according to an embodiment of the present invention. This image forming apparatus corresponds to a specific example of the “image forming apparatus” of the present invention, and uses an electrophotographic method to form an image (for example, a color image) on a medium PM to be printed, such as paper or a film. Printer. The image forming apparatus includes a medium supply unit 1, a transport unit 2, an image forming unit 3, a transfer unit 4, a fixing unit 5, a discharge unit 6, a control unit 7, and a power supply circuit 8 inside a housing 100. The control unit 7 controls the operations of the medium supply unit 1, the transport unit 2, the image forming unit 3, the transfer unit 4, the fixing unit 5, and the discharge unit 6.

  In this specification, a passage through which the medium PM is transported is referred to as a transport path. In the transport path, a direction toward the medium supply unit 1 or a position closer to the medium supply unit 1 as viewed from any component is referred to as upstream. In the transport path, a direction opposite to the direction toward the medium supply unit 1 as viewed from any component or a position further away from the medium supply unit 1 is referred to as downstream. In the transport path, a direction in which the medium PM advances (that is, a direction from the upstream to the downstream) is referred to as a transport direction F. A direction (for example, the X-axis direction in FIG. 1) that is parallel to the medium PM conveyed along the conveyance path and orthogonal to the conveyance direction F is called a width direction. The dimension in the transport direction F is called length, and the dimension in the width direction is called width. The X axis is a specific example corresponding to the “axis” of the present invention.

(Medium supply unit 1)
The medium supply unit 1 supplies the medium PM to the transport unit 2 one by one. The medium supply unit 1 includes, for example, a cassette 1A, a pickup roller 1B, and a feed roller 1C. The cassette 1A stores a plurality of media PM in a stacked state. The cassette 1A is detachably mounted, for example, at the lower part of the image forming apparatus. The pickup roller 1B and the feed roller 1C function to sequentially feed the medium PM stored in the cassette 1A to a transport path leading to the transport unit 2. Under the control of the control unit 7, the pickup roller 1B and the feed roller 1C rotate in a direction in which the medium PM is fed out toward the downstream transport unit 2. The pickup roller 1B is arranged at a position where it can come into contact with the upper surface of the uppermost medium PM. The feed roller 1C is arranged downstream of the pickup roller 1B.

(Transport section 2)
The transport unit 2 transports the medium PM from the medium supply unit 1 to the transfer unit 4 while restricting the skew. The transport unit 2 has, for example, two registration roller pairs 2A and 2B.

(Image forming unit 3)
The image forming unit 3 forms a toner image on the medium PM transported from the transport unit 2. The image forming unit 3 includes, for example, four image forming units 30K, 30Y, 30M, and 30C as shown in FIG.

  The image forming units 30K, 30Y, 30M, and 30C form toner images (images) of each color using the corresponding toner T of each color, that is, black toner, yellow toner, magenta toner, and cyan toner. . The toner T is one specific example corresponding to the “developer” of the invention. As the toner T, a negatively charged pulverized toner obtained by mixing polyester as a binder resin and carbon black, copper phthalocyanine pigment or quinacridone pigment as various colorants can be used. The volume average particle size is, for example, about 5.8 μm. Further, various additives may be added to control fluidity, chargeability, storage stability, durability and the like. Such additives include, for example, titanium oxide, alumina, PMMA or silica. Silica that has been subjected to a silicone oil treatment, a disilazane treatment, or the like may be used. Additives having a primary particle diameter of, for example, 7 nm, 12 nm, 14 nm, 21 nm, 40 nm, 200 to 300 nm, and the like can be used arbitrarily in combination.

  For example, the image forming units 30 are arranged in the order of the image forming unit 30K, the image forming unit 30Y, the image forming unit 30M, and the image forming unit 30C from upstream to downstream along the transport direction F. In the present specification, when the four image forming units 30K, 30Y, 30M, and 30C are not distinguished, they are collectively described as an image forming unit 30. The image forming unit 3 includes toner cartridges 31K, 31Y, 31M, and 31C for storing toners of respective colors, and exposure devices 32K, 32Y, 32M, and 32C, which correspond to the image forming units 30K, 30Y, 30M, and 30C, respectively. Is further provided. In this specification, the four toner cartridges 31K, 31Y, 31M, and 31C may be collectively described as a toner cartridge 31, and the four exposure devices 32K, 32Y, 32M, and 32C may be collectively described as an exposure device 32. is there. The toner cartridge 31 is configured to be detachable from the image forming unit 30. However, the toner cartridge 31 and the image forming unit 30 may be integrated.

  FIG. 2 is a schematic diagram illustrating an internal configuration of the image forming unit 30. As shown in FIG. 2, the image forming unit 30 includes a developing device 301 and a drum unit 302. A toner cartridge 31 is detachably mounted on the upper part of the developing device 301.

  The developing device 301 includes, for example, a supply roller 11, a stirring member 12, a conveying spiral 13, a doctor blade 14, a rib 15, and a developing roller 16 inside a housing 33. The toner cartridge 31 is mounted above the housing 33, and a discharge port 31 </ b> H for discharging the toner T is provided below the toner cartridge 31.

  The housing 33 has an input port 33K for receiving the toner T at an upper portion facing the discharge port 31H. The insertion port 33K is provided at a portion other than both ends in the width direction (X-axis direction) of the housing 33, and particularly preferably at a center portion in the width direction. The housing 33 further has an internal space 33A in which the toner T from the toner cartridge 31 is temporarily stored, and the supply roller 11, the stirring member 12, the transport spiral 13, the doctor blade 14 And a developing roller 16 and the like. The housing 33 is a specific example corresponding to the “container” of the present invention.

  The supply roller 11 is located at the lowermost part of the internal space 33A, that is, on the opposite side to the input port 33K, and is a substantially columnar rotating body that functions as a “developer supply member” that supplies the toner T to the development roller 16. . As shown in FIG. 2, the supply roller 11 has, for example, a two-layer structure of a shaft (core bar) 11A and an elastic layer 11B covering the outer peripheral surface of the shaft 11A. A coat layer may be further provided so as to cover the outer peripheral surface (surface) of the elastic layer 11B. The shaft 11A is made of a material having good conductivity, for example, a metal material including iron (Fe), aluminum (Al), a SUM material, stainless steel, or the like, and is, for example, a columnar member having a diameter of about 6 mm. As a constituent material of the elastic layer 11B, for example, a foamed elastic material having a plurality of cells (voids) therein, specifically, a rubber material such as foamed silicone rubber or foamed urethane is used. The elastic layer 11B has, for example, an Asker F hardness of about 50 ° and a thickness of about 3.5 mm. The supply roller 11 and the developing roller 16 are arranged so that the surface of the supply roller 11 and the surface of the developing roller 16 are in contact with each other. Here, the supply roller 11 rotates around the shaft 11A extending in the X-axis direction in the same direction as the developing roller 16 (in this example, counterclockwise as indicated by an arrow in FIG. 2), so that the developing roller 16 is rotated. Is supplied to the surface of the toner. Therefore, at the contact portion between the supply roller 11 and the development roller 16, the surface of the supply roller 11 and the surface of the development roller 16 move in opposite directions.

  The stirring member 12 is, for example, a rotating member formed by connecting two rod-shaped members having a diameter of 2 mm, and stirs the toner T existing in the internal space 33 </ b> A of the housing 33. The agitating member 12 is configured to rotate (rotate clockwise in FIG. 2) in a direction indicated by an arrow in FIG. 2, for example, about an axis 12J extending in the X-axis direction, and the rotation diameter is, for example, 8 mm. . The stirring member 12 is located upstream of the opposing portion between the supply roller 11 and the developing roller 16 and downstream of the opposing portion of the conveying spiral 13 and the supply roller 11 in the rotation direction of the supply roller 11.

  As shown in FIG. 3A, the transport spiral 13 has a substantially cylindrical shaft 13J extending in the X-axis direction, and a spiral that stands on the peripheral surface and turns along the extending direction (X-axis direction) of the shaft 13J. 13T. FIG. 3A is a plan view illustrating the internal configuration of the image forming unit 30 and parallel to the XZ plane. The transport spiral 13 rotates the shaft 13J extending in the X-axis direction as a center, thereby moving the toner T in the internal space 33A away from, for example, the input port 33K at the center in the X-axis direction (“first axial direction”). Thus, it is a member that conveys to both ends in the X-axis direction. That is, the toner T is transported in the direction of arrow Y13L or the direction of arrow Y13R along the X axis. As illustrated in FIG. 3A, the transport spiral 13 includes a transport portion 13A that transports the toner T in the direction of the arrow Y13L (“first direction”) and the direction of the arrow Y13R (““) that is opposite to the direction of the arrow Y13L. Transport portion 13B for transporting the toner T in the second direction "). It is desirable that the width occupied by the transport portion 13A and the width occupied by the transport portion 13B are substantially equal in the X-axis direction. The diameter of the shaft 13J is, for example, about 7 mm, and the height of the protrusion 13T from the surface of the shaft 13J is, for example, about 2 mm. The turning pitch of the spiral projection 13T in the X-axis direction is about 10 mm. The transport spiral 13 is located downstream of the opposing portion between the supply roller 11 and the rib 15 and upstream of the opposing portion of the supply roller 11 and the developing roller 16 in the rotation direction of the supply roller 11. The transport spiral 13 is located between the input port 33K and the supply roller 11. The transport spiral 13 is a specific example corresponding to the “developer transport member” of the invention.

  The doctor blade 14 is a toner regulating member that forms a layer (toner layer) made of the toner T on the surface of the rotating developing roller 16 and regulates (controls and adjusts) the thickness of the toner layer. The doctor blade 14 is a plate-like elastic member (leaf spring) made of stainless steel such as JIS SUS304, for example, and the distal end of the plate-like elastic member is arranged so as to slightly contact the surface of the developing roller 16. I have.

  As shown in FIGS. 3A and 3B, the rib 15 is a protruding portion of the inner surface 33 </ b> S of the housing 33, which is provided on an opposing surface facing the supply roller 11, and extends along the X-axis direction, for example. There are more than one. The rib 15 extends in a direction inclined with respect to the rotation direction of the supply roller 11, and causes the toner T flowing between the supply roller 11 and the inner surface 33 </ b> S of the housing 33 to rotate along with the rotation of the supply roller 11 along the X axis. To guide in the directions of arrows Y15L and Y15R inclined with respect to (see FIG. 3A). That is, the rib 15 is a specific example corresponding to the “developer guide member” of the invention. The rib 15 is provided at a position corresponding to the transport portion 13A and guides the toner T to an arrow Y15L (“third direction”). The rib 15 is provided at a position corresponding to the transport portion 13B and an arrow Y15R ( And a guide portion 15B for guiding the toner T in the “fourth direction”). It is desirable that the width occupied by the guide portion 15A and the width occupied by the guide portion 15B are substantially equal in the X-axis direction. 3A and 3B, the rib 15 in the guide portion 15A is indicated by reference numeral 15L, and the rib 15 in the guide portion 15B is indicated by reference numeral 15R. The directions of the arrows Y15L and Y15R include a component in a direction in which the toner T approaches the input port 33K, and are inclined at, for example, about 60 ° with respect to the X-axis direction (about 30 ° with respect to the rotation direction of the supply roller 11). ing. That is, the ribs 15 move the toner T so as to approach the inlet 33K (toward the center in the width direction) while moving the toner T upward from the vicinity of the lowermost part of the housing 33 when the supply roller 11 rotates. Is available. The inclination of the rib 15L and the inclination of the rib 15R are preferably substantially symmetric with respect to the rotation surface of the supply roller 11. The rib 15 has a height of, for example, 2.5 mm based on the inner surface 33S. The interval between adjacent ribs 15 is about 15 mm. FIG. 3B is a cross-sectional view taken along the line IIIB-IIIB shown in FIG.

  The developing roller 16 carries the toner T on the surface thereof, supplies the toner T to the photosensitive drum 34 (described later), and develops the toner T on the electrostatic latent image carried on the surface of the photosensitive drum 34. It is a columnar rotating body. The developing roller 16 is disposed to face the photosensitive drum 34 so that the surface thereof contacts the photosensitive drum 34. The developing roller 16 has, for example, a shaft 16A and an elastic layer 16B covering the outer periphery (surface) thereof. The shaft 16A is made of a material having good conductivity, for example, a metal material including iron (Fe), aluminum (Al), stainless steel, or the like, and is, for example, a columnar member having a diameter of about 7 mm. As a constituent material of the elastic layer 16B, for example, a rubber material such as silicone rubber or urethane is used. Specific examples include those using a polyether-based polyol and an aliphatic isocyanate as base polymers. The elastic layer 16B may contain, for example, carbon black such as acetylene black or Ketjen black as a conductive agent in order to adjust the resistance value. Further, the surface of the elastic layer 16B may be subjected to an isocyanate treatment. This is because the charging characteristics on the surface of the developing roller 16 are made more uniform, and the toner T is appropriately carried on the developing roller 16. For the isocyanate treatment, for example, an isocyanate treatment solution obtained by adding the above-described carbon black to a solution obtained by dissolving an isocyanate compound in an organic solvent such as ethyl acetate may be used. As the isocyanate compound, for example, diphenylmethane isocyanate, paraphenylene diisocyanate, tolylene diisocyanate, or the like is used. The isocyanate treatment is performed by adhering the above-mentioned isocyanate treatment liquid to the surface of the elastic layer 16B and drying it, and then wiping the surface of the elastic layer 16B with, for example, a cloth impregnated with isopropyl alcohol. The elastic layer 16B has, for example, Asker C hardness of about 60 ° and a thickness of about 3.5 mm. The developing roller 16 rotates in the same direction as the supply roller 11 (in this example, rotates counterclockwise as shown by the arrow in FIG. 2 (the direction opposite to the photosensitive drum 34)). The developing roller 16 corresponds to a specific example of the “developer carrier” in the present invention.

  The drum unit 302 includes, for example, a photosensitive drum 34, a charging roller 35, a cleaning device 36, and the like inside a housing 33 common to the developing device 301. In FIG. 2, a part of the housing 33 is omitted to enhance visibility.

  The exposure device 32 is provided so as to be capable of exposing the photosensitive drum 34, and is, for example, an LED head having a light emitting element such as an LED (Light Emitting Diode) and a lens array. The exposure device 32 forms an electrostatic latent image on the surface (surface layer) of the photosensitive drum 34 by irradiating the surface (surface layer) of the photosensitive drum 34 with light in units of print dots.

  The photosensitive drum 34 is a substantially columnar member capable of carrying an electrostatic latent image on the surface (surface layer portion), and is configured using a photosensitive member (for example, an organic photosensitive member). Specifically, the photosensitive drum 34 has a hollow conductive support 34A and a photosensitive layer (photoconductive layer) 34B covering the outer periphery (surface) thereof. The conductive support 34A is made of, for example, a metal pipe made of aluminum. The photoconductive layer 34B has, for example, a structure in which a charge generation layer and a charge transport layer are sequentially stacked. The photosensitive drum 34 is rotated by a predetermined peripheral speed in a direction in which the medium PM is transported in the transport direction F under the control of the control unit 7. The photosensitive drum 34 rotates in a direction opposite to that of the developing roller 16 (in this example, clockwise as indicated by an arrow in FIG. 2). The photosensitive drum 34 corresponds to a specific example of the “image carrier” of the present invention.

  The charging roller 35 is a member (charging member) that charges a surface portion (photosensitive layer 34B) of the photosensitive drum 34, and is arranged so as to be in contact with the surface of the photosensitive drum 34. The charging roller 35 has, for example, a metal shaft and a semiconductive rubber layer (for example, a semiconductive epichlorohydrin rubber layer) covering the outer periphery (surface). The charging roller 35 is controlled by the control unit 7 and rotates in a direction opposite to the photosensitive drum 34 (in this example, counterclockwise as indicated by an arrow in FIG. 2).

  The cleaning device 36 is a device that collects the toner T remaining on the surface (surface layer portion) of the photosensitive drum 34 without being transferred to the medium PM, and includes a cleaning blade 361, a drum film 362, a case 363, and waste toner conveyance. And a spiral 364. The cleaning blade 361 is a member that scrapes the toner T remaining on the surface (surface layer portion) of the photosensitive drum 34 without being transferred to the medium PM and cleans the surface of the photosensitive drum 34. The cleaning blade 361 is disposed so as to abut against the surface of the photosensitive drum 34 by a counter (projects in a direction opposite to the rotation direction of the photosensitive drum 34). Such a cleaning blade 361 is made of, for example, an elastic body such as polyurethane rubber. The drum film 362 is a member that guides the toner T (waste toner) scraped off by the cleaning blade 361 so that the toner T (waste toner) does not fall to a lower medium conveyance path. The case 363 is a container that temporarily stores the toner T (waste toner) scraped off by the cleaning blade 361. The waste toner transport spiral 364 transports the toner T (waste toner) stored in the case 363 toward a predetermined waste toner storage unit.

(Transfer unit 4)
The transfer unit 4 is also called a transfer belt unit. The transfer section 4 is disposed to face the photosensitive drum 34 with the transfer belt 4A, a driving roller 4B for driving the transfer belt 4A, an idle roller 4C driven by the drive roller 4B, and the transfer belt 4A. And a transfer roller 4D. Each of the drive roller 4B and the idle roller 4C is a substantially columnar member rotatable around a rotation shaft extending in the width direction. The transfer unit 4 transports the medium PM transported from the transport unit 2 along the transport direction F, and sequentially transfers the toner images formed in the image forming units 30Y, 30M, 30C, and 30K to the surface of the medium PM. It is a mechanism for transferring.

  The transfer belt 4A is an endless elastic belt made of a resin material such as a polyimide resin, for example. The transfer belt 4A is stretched (stretched) by a driving roller 4B and an idle roller 4C. The drive roller 4B is driven to rotate in a direction in which the medium PM is transported in the transport direction F based on the control of the control unit 7, and circulates and rotates the transfer belt 4A. The drive roller 4B is disposed upstream of the image forming units 30Y, 30M, 30C, 30K. The idle roller 4C adjusts the tension applied to the transfer belt 4A by the urging force of the urging member. The idle roller 4C rotates in the same direction as the drive roller 4B, and is disposed downstream of the image forming units 30Y, 30M, 30C, and 30K.

  The transfer roller 4D rotates the toner image formed in each of the image forming units 30Y, 30M, 30C, and 30K while rotating the photosensitive drum 34 in a direction opposite to that of the photosensitive drum 34 to transport the medium PM in the transport direction F. This is a member for electrostatic transfer on the top. The transfer roller 4D is made of, for example, a foamed semiconductive elastic rubber material.

(Fusing unit 5)
The fixing unit 5 is a member for fixing the toner image onto the medium PM by applying heat and pressure to the toner image transferred onto the medium PM that has passed through the transfer unit 4. The fixing unit 5 includes, for example, an upper roller 5A and a lower roller 5B.

  The upper roller 5A and the lower roller 5B each include a heat source as a heater such as a halogen lamp inside each, and function as a heating roller for applying heat to the toner image on the medium PM. The upper roller 5A rotates under the control of the control unit 7 in a direction in which the medium PM is transported in the transport direction F. The heat sources in the upper roller 5A and the lower roller 5B are supplied with a bias voltage controlled by the controller 7, and control the surface temperatures of the upper roller 5A and the lower roller 5B. The lower roller 5B is disposed opposite to the upper roller 5A so as to form a pressure contact portion between the lower roller 5A and the lower roller 5B, and functions as a pressure roller that applies pressure to a toner image on the medium PM. I do. The lower roller 5B preferably has a surface layer made of an elastic material.

(Ejection unit 6)
The discharge unit 6 discharges the medium PM on which the toner image has been fixed by the fixing unit 5 to the outside. The discharge unit 6 has, for example, transport rollers 6A and 6B. The transport rollers 6A and 6B discharge the medium PM to the outside via the transport path, and stock the medium PM in the external stacker 100A. Under the control of the control unit 7, the transport rollers 6A and 6B rotate in a direction in which the medium PM is transported in the transport direction F.

  FIG. 4 is a block diagram illustrating an overall configuration of the image forming apparatus illustrated in FIG. In this image forming apparatus, as shown in FIG. 4, the control unit 7 includes an interface (I / F) control unit 37, a print control unit 38, an exposure control unit 32S, a fixing control unit 5S, and a drive control unit 39S. . The power supply circuit 8 has a development power supply 16V, a supply power supply 11V, a charging power supply 35V, and a transfer power supply 4DV. Further, the image forming apparatus includes a drive motor 39 for driving the photosensitive drum 34 and the like. In this image forming apparatus, the agitating member 12, the conveying spiral 13, the developing roller 16, the supply roller 11, and the charging roller 35 rotate in conjunction with the driving force of the driving motor 39.

  The I / F control unit 37 receives print data and control commands from an external device such as a personal computer (PC), or transmits a signal relating to the state of the image forming apparatus.

  The print control unit 38 includes a microprocessor, a ROM, a RAM, an input / output port, and the like, and controls the entire processing operation in the image forming apparatus by executing, for example, a predetermined program. Specifically, the print control unit 38 receives print data and control commands from the I / F control unit 37, and controls printing of the exposure apparatus control unit 10S, the fixing control unit 5S, and the drive control unit 39S to perform printing. Perform the operation.

  The exposure controller 32S sends the image data to the exposure device 32 and controls the driving of the exposure device 32.

  The fixing control unit 5S controls the voltage applied to the fixing unit 5 when fixing the toner image transferred to the medium PM to the medium PM.

  The drive control section 39S controls the operation of the drive motor 39 and the like.

  The developing power supply 16V, the supply power supply 11V, the charging power supply 35V, and the transfer power supply 4DV apply voltages based on instructions from the print control unit 38 to the developing roller 16, the supply roller 11, the charging roller 35, and the transfer roller, respectively. 4D. When a voltage is applied to the developing roller 16 by the developing power supply 16V, the toner T carried by the developing roller 16 is developed on the electrostatic latent image formed on the surface of the photosensitive drum 34. Further, when a voltage is applied to the supply roller 11 by the supply power supply 11V, the toner T is supplied from the supply roller 11 to the developing roller 16. Further, when a voltage is applied to the charging roller 35 by the charging power supply 35V, the surface of the photosensitive drum 34 is charged. When a voltage is applied to the transfer roller 4D by the transfer power supply 4DV, the toner image developed on the surface of the photosensitive drum 34 can be transferred to the medium PM.

[Action / Effect]
(A. Basic operation)
In this image forming apparatus, a toner image is transferred to the recording medium PS as described below.

  When print image data and a print command are input from an external device such as a PC to the image forming apparatus in the activated state via the I / F control unit 37 to the print control unit 38, the print control unit 38 Accordingly, the printing operation of the print image data is started in cooperation with the drive control unit 39S and the like.

  The drive control unit 39S drives the drive motor 39 to rotate the photosensitive drum 34 at a constant speed in the direction of the arrow shown in FIG. When the photosensitive drum 34 rotates, its power is transmitted to the supply roller 11, the stirring member 12, the transport spiral 13, the developing roller 16, and the charging roller 35 via a drive transmission unit such as a gear train. As a result, the supply roller 11, the stirring member 12, the transport spiral 13, the developing roller 16, and the charging roller 35 rotate in the directions of the arrows shown in FIG. 2, respectively.

  On the other hand, the print control unit 38 applies a predetermined voltage from the charging power supply 35V to the charging roller 35 to uniformly charge the surface of the photosensitive drum 34.

  Next, the exposure control unit 32S activates the exposure device 32, and irradiates the photosensitive drum 34 with light corresponding to a print image based on an image signal to form an electrostatic latent image on the surface of the photosensitive drum 34. Further, the developing device 301 develops the toner T on the electrostatic latent image formed on the surface of the photosensitive drum 34 as described below.

  Specifically, first, a supply shutter (not shown) is rotated, and the toner T is supplied to the internal space 33A through the discharge port 31H and the supply port 33K. Here, the drive control unit 39S drives the drive motor 39 to rotate the photosensitive drum 34. By the rotation of the photosensitive drum 34, the supply roller 11, the stirring member 12, the transport spiral 13, the developing roller 16, and the charging roller 35 also start rotating. The toner T sequentially stirred by the stirring member 12 is carried by the supply roller 11 and moves to the vicinity of the developing roller 16 with the rotation of the supply roller 11. The toner T is supplied to the developing roller 16 by, for example, being negatively charged by friction between the developing roller 16 and the supply roller 11 and by a potential difference between the potential of the developing roller 16 and the potential of the supply roller 11. The toner T supplied to the developing roller 16 forms a toner layer regulated to a predetermined thickness by the doctor blade 14.

  On the other hand, when a predetermined voltage is applied to the charging roller 35 by the charging power supply 35V, the surface of the photosensitive drum 34 is uniformly charged. After that, the surface of the photosensitive drum 34 is irradiated with irradiation light from the exposure device 32 and exposed, so that an electrostatic latent image corresponding to the print pattern is formed on the surface of the photosensitive drum 34. Further, the toner layer on the developing roller 16 is developed in accordance with the electrostatic latent image on the photosensitive drum 34, and a toner image is formed on the photosensitive drum 34. The toner image is transferred to the medium PM by an electric field between the transfer roller 4D to which a predetermined voltage is applied by the transfer power supply 4DV, which is disposed to face the photosensitive drum 34.

  Thereafter, in the fixing unit 5, heat and pressure are applied to the toner image transferred onto the medium PM, and the toner image is fixed on the medium PM. After that, the medium PM on which the toner image is fixed is discharged to the outside by the discharge unit 6. The toner T that has not been transferred to the medium PM may slightly remain on the photosensitive drum 34, and the remaining toner T is removed by the cleaning blade 361. Therefore, the photosensitive drum 34 can be used continuously.

(B. Operation and Effect of Image Forming Apparatus)
In this image forming apparatus, the toner T remaining on the surface of the developing roller 16 without being used for forming a toner image on the photosensitive drum 34 is supplied to the developing roller 16 by the supply roller 11 at a portion where the developing roller 16 and the supply roller 11 face each other. 16 are scraped off the surface. The toner T scraped off by the supply roller 11 in this manner is conveyed to an area where the supply roller 11 and the housing 33 face each other as the supply roller 11 rotates. Then, the toner is again supplied to the developing roller 16 by the supply roller 11 and used for the developing process. By the way, it is considered that the toner T not used in the development is damaged by friction between the developing roller 16 and the supply roller 11, the doctor blade 14, and the photosensitive drum 34, for example. Therefore, it is not desirable that such damaged toner T remains while being repeatedly damaged without being used for development, for example, in a part of the width direction (X-axis direction). This is because there is a possibility that quality deterioration such as uneven density of the toner image may be caused.

  Therefore, in the present embodiment, the ribs 15 are provided in addition to the transport spiral 13 inside the housing 33 of the developing device 301. By doing so, the toner T is guided by the action of the rib 15 in the directions of the arrows Y15L and Y15R with the rotation of the supply roller 11. That is, the toner T scraped off by the supply roller 11 flows upward from the vicinity of the lowermost part of the housing 33 with the rotation of the supply roller 11 due to the presence of the rib 15, and the input port 33 </ b> K positioned at the center in the width direction. Move closer to. After that, the toner T is transported by the transport spiral 13 in the X-axis direction (the direction of arrow Y13L and the direction of arrow Y13R). For this reason, the toner T effectively circulates in the internal space 33A of the housing 33, and the toner T is prevented from staying or aggregating at a specific location in the width direction (X-axis direction). At this time, since the insertion port 33K exists above the transport spiral 13, the new toner T which has not been damaged, which is input from the insertion port 33K, is once carried on the developing roller 16 and then supplied by the supply roller 11. The toner T is sufficiently mixed with the scraped toner T. That is, in the developing device 301, the transport spiral 13 and the rib 15 are used in combination, so that the toner T can be effectively moved in the width direction orthogonal to the transport direction while being transported in the rotation direction of the supply roller 11. .

  As described above, according to the developing device 301, the image forming unit 30, and the image forming apparatus as one embodiment of the present invention, the flow of the toner T is promoted in the housing 33. Variations in the quality of the toner T are less likely to occur. Therefore, it is suitable for forming an excellent image.

<2. Experimental example>
(Experimental example 1)
As Experimental Example 1, an image forming apparatus provided with the developing device 301 having the rib 15 and the transport spiral 13 described in the above embodiment was prepared, and the stability of print density was evaluated. Table 1 shows the results.

Here, a toner T having an agglomeration degree a of 10% or more and 70% or less as measured in the following manner was used. The cohesion degree a, which is an index of fluidity, is determined by measuring the toner T to be measured in an environment at a temperature of 23 ° C. and a humidity of 50% for 24 hours or more, and then using a measuring device “Powder Tester PT-S” manufactured by Hosokawa Micron Corporation. Measured. More specifically, the test was performed according to the following (procedure 1) to (procedure 4) in an environment of a temperature of 23 ° C. and a humidity of 50%.
(Procedure 1) 2.0 g of the toner T is weighed by a precision balance.
(Procedure 2) A 400-mesh (opening 38 μm) sieve, a 200-mesh (opening 75 μm) sieve and a 100-mesh (opening 150 μm) sieve are sequentially stacked on the measuring instrument.
(Procedure 3) After weighing 2.0 g of the toner T weighed in Procedure 1 on a 100-mesh sieve (opening 150 μm) on a 100-mesh sieve, vibrated at 1 mm for 90 seconds. Let it.
(Procedure 4) The weight of the toner T remaining on each sieve is measured with a precision balance.
The cohesion degree a was determined by the following equation (1).
(Cohesion degree a) = x + y + z (%) (1)
However,
x = (weight of toner T remaining on a 100-mesh sieve) /2.0*100
y = 0.6 * (weight of toner T remaining on the 200-mesh sieve) /2.0*100
z = 0.2 * (weight of toner T remaining on 400 mesh sieve) /2.0*100
It is.
The smaller the cohesion degree a, the higher the fluidity of the toner T, and the smaller the cohesion between the toners T and the adhesion to the inner surface 33S of the housing 33. If the agglomeration degree a is less than 10%, the fluidity is very high, and there is a concern that the toner T may flow out of the housing 33. On the other hand, if the agglomeration degree a exceeds 70%, it becomes difficult to reproduce fine lines, isolated dots, and the like in a printed image with high accuracy.

  The print density was evaluated as follows. First, one print was performed using the “print pattern 1” shown in FIG. 5A, and density measurement was performed on the 100% duty patches P1 to P5 printed on the lanes LN1 to LN5 (see “Table 1”). Before printing pattern 2 "). Next, the band-shaped print images B1 and B2 shown in FIG. 5B are changed so that the toner T is selectively consumed only in a partial area (here, lanes LN2 and LN4) in the main scanning direction (X-axis direction). 2,000 sheets were printed in the “print pattern 2” including the “print pattern 2”. The print images B1 and B2 are printed at 100% duty on the lanes LN2 and LN4, respectively, and the print images are not printed on the other lanes LN1, LN3 and LN5. After that, one print of the “print pattern 1” shown in FIG. 5A was printed again, and the density measurement was performed on the patches P1 to P5 of 100% duty printed on the lanes LN1 to LN5 (see Table 1). No. 1 “after pattern 2 printing”). For measurement of print density, a measuring device “X-Rite528” manufactured by X-Rite Co., Ltd. was used. Table 1 shows the print densities of the patches P1 to P5 in the lanes LN1 to LN5 for “before pattern 2 printing” and “after pattern 2 printing”.

(Experimental example 2)
As an experimental example 2, an image forming apparatus including a developing device having the same configuration as that of the experimental example 1 was prepared except that neither the rib 15 nor the transport spiral 13 was provided. The print density was evaluated. The results are shown in Table 1.

(Experimental example 3)
As Experimental Example 3, an image forming apparatus provided with a developing device having the same configuration as in Experimental Example 1 except that the transport spiral 13 was not provided was prepared, and the same evaluation of print density as in Experimental Example 1 was performed. did. The results are shown in Table 1.

  As shown in Table 1, in the experimental example 2, in the lanes LN2 and LN4 where the band-shaped print images B1 and B2 were printed when the print pattern 2 was printed, the print density of “before pattern 2 printing” and the “pattern 2 print” The difference from the “after” print density was small. However, in the other lanes LN1, LN3, and LN5, an increase in the print density "after pattern 2 printing" was observed. In Experimental Example 2, since both the rib 15 and the transport spiral 13 are missing, the circulation (flow) of the toner T in the main scanning direction (X-axis direction) is particularly insufficient, and the toner T in the main scanning direction (X-axis direction) is insufficient. It is considered that a large variation occurred in the quality of the toner T.

  Further, in Experimental Example 3, in lane LN3 located at the center in the main scanning direction (X-axis direction), an increase in print density “after pattern 2 printing” was observed. This is due to an increase in the density of the toner T at the center in the main scanning direction (X-axis direction). In other words, the toner T is guided toward the center in the main scanning direction (X-axis direction) by the action of the rib 15, while the toner T collected in the center is main-scanned due to the absence of the transport spiral 13. This is because it was not possible to forcibly move to both ends in the direction (X-axis direction). As a result, it is considered that the supply amount of the toner T to the developing roller 16 by the supply roller 11 at the central portion in the X-axis direction became excessive, and the regulation of the thickness of the toner layer by the doctor blade 14 was considered to be insufficient.

  On the other hand, in Experimental Example 1, the difference between the print density before “Pattern 2 printing” and the print density after “Pattern 2 printing” is extremely small and the main scanning is different from Experimental Examples 2 and 3. It was confirmed that the variation of the print density in the direction (X-axis direction) was extremely small. In Experimental Example 1, the toner T in the main scanning direction (X-axis direction) is actively circulated (flowed) by the action of both the rib 15 and the transport spiral 13, and the toner in the main scanning direction (X-axis direction) is particularly active. It is considered that the variation in the quality of T and the variation in the density of the toner T could be suppressed. That is, according to the present invention, it was confirmed that the toner T can be effectively circulated inside the housing 33 of the developing device 301, so that an extremely stable and uniform print density can be obtained.

<3. Modification>
As described above, the present invention has been described with reference to the embodiments and the experimental examples. However, the present invention is not limited to the above embodiments and the like, and various modifications are possible. For example, in the above embodiments and the like, an image forming apparatus that forms a color image has been described. However, the present invention is not limited to this. For example, an image forming apparatus that transfers only a black toner image to form a monochrome image It may be. Further, in the above embodiment, the image forming apparatus of the primary transfer type (direct transfer type) has been described, but the present invention can be applied to the secondary transfer type.

  Further, in the above embodiments and the like, an LED head using a light emitting diode as a light source is used as an exposure device. However, an exposure device using a laser element or the like as a light source may be used.

  Further, in the above embodiments and the like, the image forming apparatus having the printing function has been described as a specific example of the “image forming apparatus” in the present invention, but the present invention is not limited to this. That is, the present invention can be applied to an image forming apparatus that functions as a multifunction peripheral having a scan function and a fax function in addition to the print function.

  Further, in the above-described embodiment and the like, for example, as shown in FIG. 3B, the cross-sectional shape of the rib 15 as the “developer guide member” of the present invention is substantially rectangular, but the present invention is not limited to this. Not something. For example, it may have a triangular or trapezoidal cross-sectional shape, or may have a cross-sectional shape including a curve such as a normal distribution. Further, the number, height, inclination angle, arrangement pitch, and the like of the ribs 15 can be arbitrarily set, and the height, inclination angle, arrangement pitch, and the like do not have to be the same for all the ribs 15. Further, the “developer guide member” of the present invention is not limited to the rib 15, but includes, for example, at least one of a concave portion and a convex portion provided on an opposing surface of the inner surface 33 </ b> S of the housing 33. You may. That is, a groove may be formed on the opposing surface of the inner surface 33S of the housing 33, or an uneven structure in which ribs (ridges) and grooves are alternately arranged on the opposing surface may be used. .

  DESCRIPTION OF SYMBOLS 1 ... Media supply part, 1A ... Cassette, 1B ... Pickup roller, 1C ... Feed roller, 2 ... Transport part, 2A, 2B ... Registration roller pair, 3 ... Image forming part, 11 ... Supply roller, 12 ... Stirring member, 13 ... Conveying spiral, 14 ... Doctor blade, 15 ... Rib, 16 ... Developing roller, 30 (30Y, 30M, 30C, 30K) ... Image forming unit, 301 ... Developing device, 302 ... Drum unit, 31 (31Y, 31M, 31C, 31) 31K) ... toner cartridge (developer container), 31H ... outlet, 32 (32Y, 32M, 32C, 32K) ... exposure device, 33 ... housing, 33K ... inlet, 34 ... photosensitive drum, 35 ... charging roller , 36 cleaning device, 4 transfer portion, 4A transfer belt, 4B drive roller, 4C idle roller, 4D transfer roller, ... fixing portion, 6 ... discharge unit, 7 ... controller, 100 ... housing, PM ... medium.

Claims (11)

An inner surface, a container and a possible opening to accept the developer provided in an upper portion, for accommodating the developer,
A developer carrying member for carrying the developer;
A developer supply member that is stored in the container and supplies the developer to the developer carrier by rotating ,
A developer transport member that is accommodated in the container and that transports the developer in a direction in which the developer supply member extends by rotating and moves away from the opening ,
Wherein one of the inner surface, the provided surface facing the developer supplying member, possess a developer guide member for guiding the developer in a direction crossing the extending direction of the developer supplying member,
The developer positioned below the developer transport member of the container is guided toward the developer transport member and the opening along the developer guide member by rotation of the developer supply member. a developing device to be. The developing device according to claim 1, wherein the developer guide member includes at least one of a concave portion and a convex portion provided on the facing surface. The developer supply member is a rotator that rotates in a first rotation direction about a rotation axis along the direction in which the developer supply member extends,
The developer transport member is located downstream of a first facing portion between the developer supply member and the developer guide member in the first rotation direction, and the developer supply member and the developer carrier The developing device according to claim 2, wherein the developing device is located upstream of the second facing portion with the body. The developing device according to claim 3, wherein the developer guide member includes one or more protruding portions extending in a direction inclined with respect to the first rotation direction. An agitating member located inside the container, downstream of a third opposing portion between the developer transport member and the developer supply member in the first rotational direction and upstream of the second opposing portion. The developing device according to claim 3, further comprising: The developer transport member is located between the opening and the developer supply member.
The developing device according to claim 1 . The opening is provided in a portion of the container other than both ends in the extending direction of the developer supply member,
The developer transport member transports the developer in a first transport portion that transports the developer in a first direction and a second direction that is opposite to the first direction and moves away from the opening. And a second transport portion that performs
The developer guide member is provided at a position corresponding to the first transport portion and guides the developer in a third direction, and at a position corresponding to the second transport portion. A second guide portion provided to guide the developer in a fourth direction.
The developing device according to claim 1 . The developing device according to claim 7 , wherein a width occupied by the first transport portion and a width occupied by the second transport portion are substantially equal in an extending direction of the developer supply member. In the extending direction of the developer supply member, the width occupied by the first guide portion is substantially equal to the width occupied by the second guide portion.
The developing device according to claim 7 . A developing device according to any one of claims 1 to 9 ,
An image carrier that carries a developer image developed by the developer carrier. An image forming apparatus comprising: a developing device according to any one of claims 1 to 9 ; and an image forming unit having an image carrier that carries a developer image developed by the developer carrier.

Images