Developing device and image forming apparatus

Abstract

To provide a developing device that, when performing final adjustment of the amount of developer with a second adjustment member, the developer being held on a surface of a developing rotating body that holds the developer having magnetism and rotates to pass through a developing area, before the developing rotating body reaches the developing area, can stabilize the amount of developer from when the developer is supplied to the surface of the developing rotating body from a first conveying member until when it reaches the second adjustment member.SOLUTION: A developing device comprises: a developing rotating body; a first conveyance member; a non-magnetic movable auxiliary member that has an inclined surface; a first adjustment member that adjusts the amount of developer from the movable auxiliary member to the developing rotating body and the amount of developer to be held on a surface of the developing rotating body; and a second adjustment member that adjusts the amount of developer held on the surface of the developing rotating body before the developing rotating body reaches a developing area. A minimum interval J3 between the inclined surface of the movable auxiliary member and an opposite surface of the first adjustment member, a minimum interval J2 between the opposite surface of the first adjustment member and the surface of the developing rotating body, and a minimum interval J1 between the second adjustment member and the surface of the developing rotating body become narrower in this order.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a developing device and an image forming apparatus. [Background technology]

[0002] The following Patent Document 1 describes a developing device that includes a developer carrier that carries and transports a two-component developer, a first regulating member that regulates the amount of developer carried and transported by the developer carrier, a developer storage section that contains developer scraped off by the first regulating member, and a toner supply opening adjacent to the developer storage section that supplies toner to the developer carrier, the developer storage section having a second regulating member disposed upstream of the first regulating member in the transport direction of the developer on the developer carrier, the second regulating member having a gap with the developer carrier to regulate the passage of an increased amount of developer when the toner concentration of the developer on the developer carrier increases and the developer layer thickness increases, and an auxiliary member made of a non-magnetic material is provided at the end of the second regulating member except for the longitudinal center portion of the second regulating member so as to protrude into the developer storage section. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4344202 (Claim 1, Figure 1, etc.) Summary of the Invention [Problem to be solved by the invention]

[0004] This invention provides a developing device and an image forming apparatus in which, when the amount of developer held on the surface of a developing rotor that rotates to pass through a developing area while holding magnetic developer is subjected to final adjustment by a second adjustment member before the amount of developer reaches the developing area, the amount of developer supplied from a supply and transport member to the surface of the developing rotor and reaching the second adjustment member is stabilized by providing a first adjustment member that adjusts the amount of developer moved from a moving auxiliary member to the developing rotor and the amount of developer held on the surface of the developing rotor, compared to a case in which the minimum distance between the inclined surface of the moving auxiliary member and the opposing surface of the first adjustment member, the minimum distance between the opposing surface of the first adjustment member and the surface of the developing rotor, and the minimum distance between the second adjustment member and the surface of the developing rotor are not narrowed in that order. [Means for solving the problem]

[0005] This invention (1) is, a developing rotor that holds a magnetic developer and rotates to pass through a developing area; a supply and transport member that rotates to transport the developer to be supplied to the developing rotor; a non-magnetic movement assisting member disposed between the developing rotary body and the supply / transport member, the non-magnetic movement assisting member having a slope for receiving the developer sent from the supply / transport member and moving the developer to the developing rotary body; a first adjustment member having opposing surfaces facing, at an interval, the inclined surface of the movement assist member and the surface portion of the developing rotor that has passed through the movement assist member, and adjusting the amount of developer moved from the movement assist member to the developing rotor and the amount of developer held on the surface of the developing rotor; a second adjustment member that is disposed at an interval on a surface portion of the developing rotary body that has passed through the first adjustment member and adjusts an amount of developer held on the surface of the developing rotary body before the developer reaches the developing area; Equipped with the movement assist member is disposed such that the inclined surface is located above a virtual straight line connecting a rotation center point of the developing rotor and a rotation center point of the supply / conveyance member, This developing device narrows the minimum distance between the inclined surface of the movement assist member and the opposing surface of the first adjustment member, the minimum distance between the opposing surface of the first adjustment member and the surface of the developing rotor, and the minimum distance between the second adjustment member and the surface of the developing rotor in this order.

[0006] This invention (2) is a developing device according to the invention (1) above, wherein the inclined surface of the movement assist member and the opposing surface of the first adjustment member have a portion in which they approach each other toward the developing rotor, reaching the minimum gap. This invention (3) is a developing device according to the above invention (1) or (2), wherein the inclination of the inclined surface of the movement support member in the portion close to the developing rotor is gentler than the inclination of the remaining portion before reaching the close portion. The present invention (4) provides the developing device according to the above invention (1) or (2), wherein the opposing surface of the first adjustment member is inclined with respect to the inclined surface of the movement auxiliary member and the developing device. Image times This is a developing device that is constructed with a curved surface that is convex toward the surface of the roller.

[0007] The present invention (5) is the developing device according to the above invention (1) or (4), wherein the first adjustment member is formed of a cylindrical member. The present invention (6) provides the developing device according to the above invention (5), wherein the first adjustment member is disposed next to the opposing surface of the movement auxiliary member. Image times This is a developing device that rotates in a direction that passes over the surface of the rolling element.

[0008] This invention (7) is a developing device according to any one of inventions (1) to (6) above, wherein the minimum distance between the part of the second adjustment member that forms the minimum distance with the developing rotor and the opposing surface of the first adjustment member is wider than the minimum distance between the opposing surface of the first adjustment member and the surface of the developing rotor. This invention (8) is the developing device of the invention (7) above, wherein the surface of the second adjustment member opposite the surface facing the surface of the developing rotor is configured in a shape such that the distance between it and the first adjustment member gradually increases. Invention (9) is a developing device according to any one of inventions (1) to (8) above, wherein the developing rotor is composed of a rotating cylindrical member and a magnetic member having a plurality of magnetic poles arranged inside the cylindrical member, and among the magnetic poles is a pick-up pole that magnetically holds the developer on the surface of the cylindrical member, and the developing device is configured so that the peak of the magnetic field line of the pick-up pole is shifted upstream in the direction of rotation of the developing rotor from the terminal end of the inclined surface of the moving auxiliary member.

[0009] This invention (10) is an image forming apparatus comprising a latent image carrier on which a latent image is held, and a developing device that develops the latent image on the latent image carrier with a developer, the developing device being configured as the developing device described in any one of inventions (1) to (9) above. Effect of the Invention

[0010] According to the above invention (1), when the amount of developer held on the surface of the developing rotor which rotates to pass through the developing area while holding magnetic developer is subjected to final adjustment by the second adjustment member before the amount of developer reaches the developing area, the amount of developer supplied from the supply and transport member to the surface of the developing rotor and reaching the second adjustment member can be stabilized by providing a first adjustment member which adjusts the amount of developer moved from the moving auxiliary member to the developing rotor and the amount of developer held on the surface of the developing rotor, compared to a case where the minimum distance between the inclined surface of the moving auxiliary member and the opposing surface of the first adjustment member, the minimum distance between the opposing surface of the first adjustment member and the surface of the developing rotor, and the minimum distance between the second adjustment member and the surface of the developing rotor are not narrowed in this order.

[0011] According to the above invention (2), it is easier to adjust the amount of developer movement while reducing the stress applied to the developer when it is moved to the developing rotor, compared to when the inclined surface of the movement assist member and the opposing surface of the first adjustment member do not have a portion where the distance between them approaches the developing rotor and reaches a minimum distance as the moving support member approaches the developing rotor. According to the above invention (3), the stress applied to the developer when it is moved to the developing rotor can be reduced more than when the inclination of the portion of the inclined surface of the movement support member close to the developing rotor is not gentler than the inclination of the remaining portion before it reaches the portion close to the inclined surface. According to the above invention (4), the opposing surface of the first adjustment member is inclined with the movement assist member. Image times Compared to a case where the developer is not configured with a curved surface that is convex toward the surface of the developing body, the developer can be moved smoothly to the developing body while reducing the stress applied to the developer when moving it to the developing body.

[0012] According to the above aspect (5), it is easier to adjust the moving amount and the retained amount of developer, compared to a case in which the first adjustment member is not configured in a cylindrical shape. According to the above aspect (6), the movement of the developer can be promoted compared to a case in which the movement auxiliary member is not rotationally driven in the above-mentioned direction.

[0013] According to the above invention (7), it is easier to move excess developer generated when the second adjustment member passes away from the developing rotor, compared to when the minimum distance between the part of the second adjustment member that forms the minimum distance with the developing rotor and the opposing surface of the first adjustment member is not wider than the minimum distance between the opposing surface of the first adjustment member and the surface of the developing rotor. According to the above invention (8), compared to a case in which the surface of the second adjustment member opposite the surface facing the surface of the developing rotor is not configured in a shape in which the distance from the first adjustment member gradually increases, excess developer generated when the second adjustment member passes can be moved more easily with reduced stress on the side moving it away from the developing rotor. According to the above invention (9), compared to a case where the peak of the magnetic field line of the pickup pole is not positioned upstream of the end portion of the slope of the moving assist member in the direction of rotation of the developing rotor, it is easier to move the developer moving through the gap space between the slope of the moving assist member and the opposing surface of the first adjustment member to the developing rotor and retain it therein.

[0014] According to the image forming apparatus of the above invention (10), when the amount of developer held on the surface of the developing rotor, which holds magnetic developer in the developing device and rotates to pass through the developing area, is adjusted by the second adjustment member before the developer reaches the developing area, the amount of developer supplied from the supply and transport member to the surface of the developing rotor and reaching the second adjustment member can be stabilized, and image quality defects such as blank streaks caused by the amount of developer being unstable before reaching the second adjustment member can be prevented. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic diagram of an image forming apparatus according to a first embodiment. [Diagram 2] FIG. 2 is a schematic diagram of a developing device according to the first embodiment. [Diagram 3] 3 is a partial cross-sectional view of the developing device taken along line III-III in FIG. 2. [Figure 4] FIG. 2 is a schematic diagram of the developing device with the upper part of the housing and the like removed. [Diagram 5] FIG. 2 is a schematic diagram of a part of the developing device and its operating state. [Figure 6] FIG. [Figure 7] 13A and 13B are schematic diagrams of modified examples of the movement assisting member. [Figure 8] FIG. 11 is a schematic diagram of a developing device according to a second embodiment. [Figure 9] FIG. 7 is a schematic diagram of a portion of the developing device in FIG. 6. [Figure 10] FIG. 7 is a schematic diagram of the developing device in FIG. 6 with the upper part of the housing removed. [Figure 11] FIG. 7 is a schematic diagram of a part of the developing device in FIG. 6 and its operating state. [Figure 12] FIG. 7 is a schematic diagram of a portion of the developing device in FIG. 6. [Figure 13] FIG. 11 is a schematic diagram of a developing device according to a third embodiment. [Figure 14] FIG. 14 is a schematic diagram of a part of the developing device in FIG. 13 and its operating state. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0017] First embodiment. FIG. 1 is a diagram showing an image forming apparatus 1 using a developing device 6A according to a first embodiment of the present invention. The arrows indicated by the symbols X, Y, and Z in each drawing such as Fig. 1 indicate the left-right direction (horizontal direction), the up-down direction (vertical direction), and the front-back direction (horizontal direction), respectively. Also, the circle at the intersection of the X and Y arrows in the drawing indicates that the Z direction is pointing vertically downward on the drawing (paper surface).

[0018] <Image forming device>

[0019] As shown in FIG. 1, the image forming apparatus 1 includes, within the internal space of a housing 10 having a required external shape, an image forming device 2 that forms a toner image composed of toner as a developer based on image information and transfers the toner image onto a recording paper 9, which is an example of a recording medium, a paper feeding device 4 that stores and supplies the recording paper 9 to be supplied to a position where the image forming device 2 performs transfer, a fixing device 5 that fixes the toner image transferred by the image forming device 2 onto the recording paper 9, and a control means (not shown). 1 indicates a main transport path along which the recording paper 9 is transported inside the housing 10. The dotted and dashed lines in FIG.

[0020] The image forming device 2 has a photosensitive drum 21, which is an example of a latent image holder on which a latent image is formed and held, and is configured by arranging equipment such as a charging device 22, an exposure device 23, a developing device 6A, a transfer device 25, and a cleaning device 26 around the photosensitive drum 21.

[0021] Of these, the photosensitive drum 21 is a drum-shaped photosensitive body that rotates in the direction indicated by the arrow A around a rotation axis (not shown) that extends along the depth direction Z. The charging device 22 is a device that charges the outer circumferential surface (image forming surface) of the photosensitive drum 21 to a required surface potential. The charging device 22 is configured to include a charging member such as a roll that is brought into contact with the image forming area of ​​the outer circumferential surface of the photosensitive drum 21 and is supplied with a charging current. The exposure device 23 is a device that exposes the charged outer circumferential surface of the photosensitive drum 21 based on image information to form an electrostatic latent image.

[0022] The developing device 6A is a device that develops the electrostatic latent image formed on the outer peripheral surface of the photosensitive drum 21 with a developer (toner) of a corresponding predetermined color (e.g., black) to form a toner image, which is an example of a visible image. The developing device 6A will be described in detail later. The transfer device 25 is a device that electrostatically transfers the toner image formed on the outer peripheral surface of the photosensitive drum 21 onto the recording paper 9. The transfer device 25 is configured to include a transfer member such as a roll that comes into contact with the outer peripheral surface of the photosensitive drum 21 and is supplied with a transfer current. The cleaning device 26 is a device that cleans the outer peripheral surface of the photosensitive drum 21 by scraping off and removing unnecessary matter such as unnecessary toner and paper powder adhering to the outer peripheral surface of the photosensitive drum 21. In the image forming apparatus 2, each portion where the photosensitive drum 21 and the transfer device 25 face each other becomes a transfer position TP where the toner image is transferred.

[0023] The paper feeder 4 is disposed below the image forming device 2. The paper feeder 4 is configured by arranging devices such as a container 41 that stores recording paper 9 and a delivery device 43 that delivers the recording paper 9 one sheet at a time. The recording paper 9 may be any medium such as plain paper, coated paper, or thick paper that can be transported within the housing 10 and to which a toner image can be transferred and fixed, and there are no particular restrictions on its material, shape, etc. The recording medium represented by the recording paper 9 may be any medium that can be transported within the housing 10 and to which a toner image can be transferred and fixed.

[0024] The fixing device 5 is disposed at a position above the transfer position TP of the image forming device 2. The fixing device 5 is configured by arranging devices such as a heating rotor 51 and a pressure rotor 52 in the internal space of a housing 50 in which an inlet and an outlet for the recording paper 9 are formed. In the fixing device 5, the heating rotator 51 and the pressure rotator 52 are arranged so as to be in contact with each other in a substantially horizontal state. In the fixing device 5, the portion where the heating rotator 51 and the pressure rotator 52 contact each other is configured as a fixing processing portion (nip portion) FN which performs processing such as heating and pressure for fixing the unfixed toner image to the recording paper 9.

[0025] The main transport path for the recording paper 9 within the housing 10 is configured by an arrangement of multiple transport rolls 45a, 45b, 45c that clamp and transport the recording paper 9, and multiple guide members (not shown) that ensure a transport space for the recording paper 9 and guide the transport of the recording paper 9.

[0026] In the image forming apparatus 1, when a control means (not shown) receives a command for an operation of forming an image, the charging operation, the exposure operation, the developing operation and the transfer operation are performed in the image forming apparatus 2, while at the same time, the feeding operation of the recording paper 9 from the paper feeding device 4 to the transfer position TP is performed. As a result, a toner image is formed on the photosensitive drum 21, and then the toner image is transferred onto the recording paper 9 supplied from the paper feeder 4 to the transfer position TP.

[0027] Next, in the image forming apparatus 1A, the recording paper 9 onto which the toner image has been transferred is introduced into the nip portion FN in the fixing device 5, where a fixing operation is performed. As a result, the unfixed toner image is fixed onto the recording paper 9 . After the fixing is completed, the recording paper 9 is transported by, for example, transport rolls 45b and 45c, and then discharged to and stored in the discharge storage section 12 provided on the upper surface of the housing 10. In this manner, the image forming operation in which a toner image is formed on one side of the recording paper 9 is completed.

[0028] <Developing device> Next, the developing device 6A according to the first embodiment will be described in detail.

[0029] 2, the developing device 6A has a housing 60 consisting of a container-like lower portion 60a that opens upward and a lid-like upper portion 60b that closes the upper portion of the lower portion 60a. The housing 60 is provided with an opening 61 for development and a storage portion 62 that stores a magnetic developer 8. As the magnetic developer 8, for example, a two-component developer containing a non-magnetic toner and a magnetic carrier is used.

[0030] The opening 61 is a rectangular opening that is long in the depth direction Z facing the development area Ed where the latent image is developed in a portion extending along the rotation axis of the photosensitive drum 21, and its inside is connected to the storage section 62. A developing roll 71, which is an example of a developing rotor that holds the developer 8 and rotates to pass through the development area Ed, is rotatably arranged in a lower part 60a on the inside of the opening 61 in the housing 60.

[0031] The developing roll 71 is composed of a developing sleeve 71a, which is an example of a cylindrical member that holds the developer 8 and rotates, and a magnet roll 71b, which is an example of a magnetic member that is fixedly arranged in the internal space of the developing sleeve 71a. The developing sleeve 71a is made of a non-magnetic material. As shown in FIG. 3, the shafts 71c and 71d at both ends of the developing sleeve 71a are rotatably attached to the left and right side walls 62c and 62d of the storage section 62 or to a support frame (not shown) provided therebetween, and the developing sleeve 71a is rotated in the direction indicated by the arrow B by the rotational power of a rotation drive device (not shown). A developing bias is supplied between the developing sleeve 71a and the photosensitive drum 21 from a power supply device (not shown). The magnet roll 71b has a plurality of magnetic poles arranged on the surface of the developing sleeve 71a, which generate magnetic forces that perform functions such as attraction (pickup), holding and conveying, and peeling of the developer 8. In FIG. 6, the reference symbol N1 indicates a pickup pole, S1 indicates a trimmer pole, N2 indicates a conveying pole, S2 indicates a developing pole, and S3 and N3 indicate peeling poles.

[0032] As shown in Figures 2 to 4, the storage section 62 is provided with a first transport path 63 along which the developer 8 to be supplied to the developing roll 71 is transported, and a second transport path 64 along which the developer 8 to be sent to the first transport path 63 is transported. The first transport path 63 and the second transport path 64 are groove-shaped portions extending substantially parallel to the developing roll 71. The first transport path 63 and the second transport path 64 are arranged vertically and are partitioned by a partition portion 65 provided between them, while they are connected to each other at a first connection portion 67 and a second connection portion 68 provided to penetrate through both ends of the downstream side and the upstream side in the transport direction. As a result, the first transport path 63 and the second transport path 64 are configured as circulating transport paths in which the developer 8 is circulated and transported, with the developer 8 being transferred to the opposite transport path at the first connection portion 67 and the second connection portion 68, respectively.

[0033] A first screw auger 72 is disposed in the first transport path 63 as an example of a first transport member that transports the developer 8 forward in the first transport direction D1 while stirring the developer 8. The first screw auger 72 in this embodiment also serves as an example of a supply transport member that rotates and transports the developer 8 to be supplied to the developing roll 71. The first screw auger 72 is provided such that a forward transport blade 72b for forward transporting the developer 8 in the first transport direction D1 is wound in a spiral shape at a predetermined height, inclination angle, and pitch around a round bar-shaped rotating shaft 72a arranged to rotate in the first transport path 63. The first screw auger 72 is also provided such that a reverse transport blade 72c for reverse transporting the developer in the opposite direction to the first transport direction D1 is wound in a spiral shape in a direction opposite to the winding direction of the forward transport blade 72b at an end of the rotating shaft 72a adjacent to the first connecting portion 67 and downstream in the first transport direction D1. Furthermore, the first screw auger 72 in this embodiment is arranged such that its top is higher than the top of the developing roll 71 in the vertical direction along the gravity direction.

[0034] In the second transport path 64, a second screw auger 73 is disposed as an example of a second transport member that transports the developer 8 forward in the second transport direction D2 while stirring the developer 8. The second screw auger 73 is provided with a round bar-shaped rotating shaft 73a arranged to rotate in the second transport path 64, and a forward transport blade 73b for forward transporting the developer 8 in the second transport direction D2 is wound in a spiral shape at a predetermined height, inclination angle, and pitch. The second screw auger 73 is provided with a plurality of plate-shaped transport blades 73c for lifting the developer 8 and sending it to the first transport path 63 on a portion of the rotating shaft 73a adjacent to the second connecting portion 68. The second screw auger 73 is further provided with a reverse transport blade 73d for reverse transporting the developer in the opposite direction to the second transport direction D2 on an end portion of the rotating shaft 73a downstream of the second transport direction D2, and is wound in a spiral shape in a direction opposite to the winding direction of the forward transport blade 73b.

[0035] The first screw auger 72 and the second screw auger 73 are rotatably attached to the left and right side wall portions 62c, 62d of the storage portion 62 or to a support frame (not shown) provided next to them. The first screw auger 72 and the second screw auger 73 are arranged so that the rotational power transmitted to the developing sleeve 71a of the developing roll 71 is distributed via a gear train mechanism (not shown), so that they rotate in a required direction, for example, in the direction of the arrow shown in FIG. 2 at a required speed.

[0036] As shown in FIGS. 2 and 4, the developing device 6A has a plate-shaped trimmer 74, a movement assisting member 75, and a first adjustment member 76A disposed in the accommodation portion 62.

[0037] The plate-shaped trimmer 74 is an example of a second adjustment member that finally adjusts the amount (layer thickness) of the developer 8 held on the developing roll 71 before the developer 8 reaches the development area Ed. 4 and 5, the plate-shaped trimmer 74 is a non-magnetic member that is elongated along the direction of the rotation axis of the developing sleeve 71a. The plate-shaped trimmer 74 has a tapered tip 74a at its lower end, and the surface opposite the opening 61 of the housing 60 forms a curved guide surface 74b that guides the developer to move toward the first screw auger 72.

[0038] The plate-shaped trimmer 74 is disposed in a portion of the upper portion 60b of the housing 60 close to the opening 61. As shown in Fig. 6, the plate-shaped trimmer 74 is attached to a predetermined portion of the lower portion 60a or upper portion 60b of the housing 60 or to a support frame (not shown) provided therebetween, with a tapered tip 74a facing the outer circumferential surface, which is the surface of the developing roll 71 (of the developing sleeve 71a), along the direction of the rotation axis of the developing sleeve 71a, with a predetermined minimum gap J3 therebetween.

[0039] The movement auxiliary member 75 is disposed between the developing roll 71 and the first screw auger 72, and is a non-magnetic member having a slope 75a that receives the developer 8 sent from the first screw auger 72 and moves it to the developing roll 71.

[0040] As shown in FIGS. 4 and 5, the movement auxiliary member 75 is a plate-like non-magnetic member that extends along the direction of the rotation axis of the developing sleeve 71a. The movement assist member 75 has a slope 75a at its upper end. The slope 75a is a surface with an inclination angle that slopes downward toward the developing sleeve 71a so that the developer 8 can slide down by its own weight. Furthermore, the movement assist member 75 has a side surface 75b on the first screw auger 72 side that is a wall surface that hangs down from the upper end to a position approaching the upper part of the second screw auger 73 in a direction substantially along the gravity direction, and a side surface 75c on the developing roll 71 side that is a wall surface that hangs down from the upper end to a position reaching the lower part of the developing roll 71 in a direction substantially along the gravity direction.

[0041] Also, the movement assist member 75 is disposed, for example, such that the inclined surface 75a is located above an imaginary line connecting the rotation center point of the developing roll 71 and the rotation center point of the first screw auger 72. Furthermore, as shown in Fig. 4 and Fig. 6, the movement assist member 75 is attached to a predetermined portion of the lower part 60a or upper part 60b of the housing 60 or a support frame (not shown) provided therebetween, in a state in which the minimum distance J6 between the movement assist member 75 and the first screw auger 72 and the minimum distance J7 between the movement assist member 75 and the developing roll 71 are predetermined values.

[0042] The first adjustment member 76A is a non-magnetic member that adjusts the amount of developer 8 moved from the moving assist member 75 to the developing roll 71 and the amount of developer 8 retained on the surface of the developing roll 71, and has an opposing surface 76a that faces, at a distance, the inclined surface 75a of the moving assist member 75 and the surface portion of the developing roll 71 that has passed through the moving assist member 75.

[0043] In this embodiment, the first adjustment member 76A is a cylindrical rod member with a part cut out at a flat surface. Therefore, the first adjustment member 76A has a shape having a curved surface portion formed by the outer circumferential surface of the cylinder and a flat surface portion 76b other than the curved surface portion, except for both ends in the longitudinal direction. The first adjustment member 76A utilizes the curved portion as the opposing surface 76a, which is a curved surface that is convex toward the inclined surface 75a of the movement auxiliary member 75 and the surface of the developing roll 71. As shown in Figs. 4 and 6, the first adjustment member 76A is attached to a predetermined portion of the lower portion 60a or upper portion 60b of the housing 60 or a support frame (not shown) provided therewith, in a state in which the minimum distance J1 of the opposing surface 76a to the inclined surface 75a of the movement auxiliary member 75 and the minimum distance J2 of the opposing surface 76a to the developing roll 71 are predetermined values. The first adjustment member 76A is also disposed so that the minimum distance J5 between the first screw auger 72 and the first adjustment member 76A is a predetermined value.

[0044] In this developing device 6A, as shown in FIG. 5, a first gap space E1 that allows developer 8 to pass through is formed between the inclined surface 75a of the movement assist member 75 and the opposing surface 76a of the first adjustment member 76A, a second gap space E2 that allows developer 8 to pass through is formed between the opposing surface 76a of the first adjustment member 76A and the surface of the developing sleeve 71a, and a third gap space E3 that allows developer 8 to pass through is formed between the tip 74a of the plate-shaped trimmer 74 and the surface of the developing sleeve 71a. In the developing device 6A, a fourth gap space E4 is formed between the opposing surface 76a of the first adjustment member 76A and the guide surface 74b of the plate-shaped trimmer 74, and a fifth gap space E5 is formed between the first screw auger 72 and the side surface portion 75b of the movement auxiliary member 75. The fifth gap space E5 approximately corresponds to the gap space between the first screw auger 72 and the first transport path 63.

[0045] The developing device 6A operates as follows.

[0046] When the time comes for the developing operation to be performed in the developing device 6A, as shown in FIG. 2, the developing sleeve 71a of the developing roll 71 starts to rotate in the direction indicated by the arrow B, and the first screw auger 72 and the second screw auger 73 also start to rotate in the directions indicated by the respective arrows.

[0047] 2 and 3, in the second transport path 64, the developer 8 is transported forward in the second transport direction D2 while being stirred by the spiral forward transport blade 73b of the rotating second screw auger 73. At this time, the toner of the developer 8, which is a two-component developer, is triboelectrically charged to a required polarity (e.g., negative polarity) by the carrier. In addition, the developer 8 transported forward to the downstream side of the second transport direction D2 of the second transport path 64 is sent to the first transport path 63 side so as to be lifted by the transport force of the plate-shaped transport blade 73c while also receiving a reverse transport force from the spiral reverse transport blade 73d at the second connection portion 68, as exemplified by the dashed arrow D3 in FIG.

[0048] In the first transport path 63, as shown in Figures 3 and 4, the developer 8 is transported in a first transport direction D1 while being agitated by a spiral forward transport blade 72b of a first screw auger 72 rotating in the direction of arrow C. At this time, as shown in Figure 6, a portion of the developer 8 transported forward by the first screw auger 72 is sent as developer 8a to the developing roll 71 side by the action of the spiral forward transport blade 72b rotating in the direction of arrow C, over the first transport path 63.

[0049] 5, the developer 8a sent out from the first screw auger 72 enters the first gap space E1 between the inclined surface 75a of the movement assist member 75 and the opposing surface 76a of the first adjustment member 76A. At this time, the developer 8 that does not enter the first gap space E1 is conveyed forward again by the first screw auger 72 in the first conveying path 63, and a part of it is sent out from the first conveying path 63 again.

[0050] 5, the developer 8b that has entered the first gap space E1 slides along the slope 75a of the movement assist member 75 while the amount passing through is restricted, and only the amount that has passed through reaches the outer circumferential surface of the developing sleeve 71a of the developing roll 71 and is held there by forming a spike-like magnetic brush due to the magnetic force from the magnet roll 71b, etc. Strictly speaking, the developer 8b is in a state where it is attracted to the surface of the developing sleeve 71a by the magnetic force from the magnet roll 71b even before it reaches the outer circumferential surface of the developing sleeve 71a. As a result, the amount of developer 8a moving to the developing roll 71 is adjusted.

[0051] Next, the developer 8c supplied to and held on the outer peripheral surface of the developing sleeve 71a is transported by, for example, rotation of the developing sleeve 71a in the direction of arrow B, and passes through the second gap E2 between the first adjustment member 76 and the outer peripheral surface of the developing sleeve 71a, as shown in Fig. 5. At this time, the developer 8c moves while the amount passing through is limited by the second gap E2. As a result, the amount of developer 8c held on the outer peripheral surface of the developing sleeve 71a is adjusted once.

[0052] Furthermore, the developer 8c that has been held on the outer peripheral surface of the developing sleeve 71a and passed through the first adjustment member 76 passes through the third gap space E3 between the developing sleeve 71a and the plate-shaped trimmer 74. At this time, the developer 8c moves while the amount passing through is restricted again by the third gap space E3 in a state where the amount of developer 8c held thereon has been adjusted once. This finally adjusts the amount of developer 8d held on the outer peripheral surface of the developing sleeve 71a.

[0053] Next, the developer 8d, which has passed under the trimmer 74 and has had its retention amount finally adjusted, is transported to reach and pass through the development area Ed on the photosensitive drum 21 by, for example, rotation of the developing sleeve 71a in the direction of arrow B. In the development area Ed, the toner of the developer 8d is moved back and forth by a development electric field formed between the developer 8d and the photosensitive drum 21 by the supply of a development bias, and some of the toner adheres to the latent image portion on the photosensitive drum 21 by electrostatic force and is used to develop the latent image. At this time, a portion 8e of the developer not used for development passes through the development area Ed, and is then subjected to the magnetic force of the repulsive magnetic field generated by the peeling poles S3 and N3 in the storage section 62, whereby the developer is peeled off from the developing sleeve 71a and returned to the second transport path 64.

[0054] In addition, excess developer 8f of the developer 8c that has passed through the first adjustment member 76 and cannot pass through the third gap space E3 between the outer peripheral surface of the developing sleeve 71a and the plate-shaped trimmer 74 is moved to be sent to the fourth gap space S4 between the opposing surface 76a of the first adjustment member 76A and the guide surface 74b of the plate-shaped trimmer 74, as shown in Figure 5. At this time, the developer 8f is moved by the guide surface 74b of the trimmer 74 so as to be returned to the side where the first screw auger 72 is located. At this time, part of the developer 8f slides along a flat surface portion 76b of the first adjustment member 76 that is inclined downwardly toward the first screw auger 72, and moves so as to be returned to the space between the first adjustment member 76 and the first screw auger 72.

[0055] In the developing device 6A, for example, if the first adjustment member 76A is not provided, developer 8 can be supplied to the developing roll 71 from the first screw auger 72. However, the amount of developer 8 supplied to the portion of the developing roll 71 upstream of the plate-shaped trimmer 74 in the rotation direction of the developing sleeve 71a in the direction of arrow B becomes unstable, and the amount of developer 8 remaining in that upstream portion may increase. As a result, the amount of developer 8 supplied to the development area Ed may become unstable, and the developer 8 may become more susceptible to stress due to its stagnation, which may result in poor image quality such as white streaks along the transport direction of the recording paper 9 in the image made of the developed toner image.

[0056] <Detailed configuration of the developing device> Therefore, in this developing device 6A, as shown in Figures 2 to 6, a configuration is adopted in which a first adjustment member 76A is provided, and the minimum distance J1 between the inclined surface 75a of the movement assist member 75 and the opposing surface 76a of the first adjustment member 76A, the minimum distance J2 between the opposing surface 76a of the first adjustment member 76A and the surface of the developing roll 71, and the minimum distance J3 between the surface of the plate-shaped trimmer 74 and the developing roll 71 are narrowed in this order.

[0057] The magnitude relationship (J1>J2>J3) among these three minimum intervals J1, J2, J3 can be established, for example, by first setting the minimum interval J3 and then setting the remaining minimum intervals J1, J2, respectively. Furthermore, the magnitude relationship (J1>J2>J3) among the three minimum intervals J1, J2, J3 is, for example, such that if the minimum interval J3 is set to a value of K, the minimum interval J2 is set to a value within the range of 2K to 5K, and the minimum interval J1 is set to a value within the range of 5K to 12K.

[0058] Incidentally, in this developing device 6A, the minimum distance J5 between the first adjusting member 76A and the first screw auger 72 is set to a value larger than the minimum distance J1 between the inclined surface 75a of the movement assisting member 75 and the opposing surface 76a of the first adjusting member 76A (J5 > J1). Also, the minimum distance J6 between the movement assisting member 75 and the first screw auger 72 is set to a value smaller than the above minimum distance J5 (J6 < J5). Further, the minimum distance J7 between the side surface portion 75c of the movement assisting member 75 and the developing roll 71 is set to a value smaller than the minimum distance J2 between the opposing surface 76a of the first adjusting member 76 and the surface of the developing roll 71 (J7 < J2).

[0059] And in the developing device 6A, after providing the first adjusting member 76A, it is configured such that the three minimum distances J1, J2, and J3 satisfy the magnitude relationship of J1 > J2 > J3. Therefore, compared with the case where it is not configured in this way, the amount of the developer 8 from the first screw auger 72 until it is supplied to the outer peripheral surface of the developing roll 71 and reaches the plate-shaped trimmer 74 becomes stable.

[0060] That is, in this developing device 6A, first, the amount of the developer 8a supplied to the outer peripheral surface of the developing roll 71 is adjusted by passing the developer 8a sent from the first screw auger 72 through the first gap space E1 between the inclined surface 75a of the movement assisting member 75 and the opposing surface 76a of the first adjusting member 76A. Subsequently, in this developing device 6A, it is passed through the second gap space E2 between the opposing surface 76a of the first adjusting member 76A and the outer peripheral surface of the developing roll 71, which is set to a minimum distance J2 narrower than the minimum distance J1 of the first gap space E1. As a result, the developer 8 when it reaches the trimmer 74 while being held on the outer peripheral surface of the developing roll 71 after being sent out from the first screw auger 72 is supplied to the trimmer 74 in a state where its holding amount is adjusted.

[0061] In addition, in the image forming apparatus 1 using this developing device 6A, the occurrence of image quality defects such as blank streaks caused by the amount of developer 8 in the developing device 6A becoming unstable before it reaches the trimmer 74 is suppressed.

[0062] In addition, in the developing device 6A, as shown in FIG. 5 etc., the inclined surface 75a of the movement assist member 75 and the opposing surface 76a of the first adjustment member 76A have a portion where they approach the developing roll 71 and reach the above-mentioned minimum gap J1. Therefore, with this developing device 6A, compared to a case in which the inclined surface 75a and the opposing surface 76a do not have such portions, the developer 8a does not remain uselessly when it is moved through the first gap space E1 to the developing roll 71, and it is easier to adjust the amount of movement of the developer 8 relative to the developing roll 71 while reducing the physical stress applied to the developer 8a when it is moved.

[0063] In the developing device 6A, the opposing surface 76a of the first adjustment member 76A is configured with a curved surface that is convex toward the inclined surface 75a of the movement auxiliary member 75 and the outer circumferential surface of the developing roll 71, as shown in FIG. Therefore, with this developing device 6A, compared to a case in which the opposing surface 76a is not configured as such a convex curved surface, it is possible to move the developer 8 to the developing roll 71 smoothly while reducing the stress applied to the developer 8a as it passes over the opposing surface 76a when being moved to the developing roll 71.

[0064] Furthermore, in the developing device 6A, as shown in FIG. 5 etc., the minimum distance J4 between the tip 74a, which is the part that forms the minimum distance J4 between the trimmer 74 and the developing roll 71, and the opposing surface 76a of the first adjustment member 76A is configured to be wider than the minimum distance J2 between the opposing surface 76a of the first adjustment member 76 and the outer peripheral surface of the developing roll 71 (J4>J2). For this reason, with this developing device 6A, the excess developer 8f generated when the trimmer 74 passes can be moved more easily into the fourth gap space E4, which is the side that moves the excess developer 8f away from the developing roll 71, with less restriction when passing through, compared to when the minimum gap J4 and the minimum gap J2 are not configured to have such a magnitude relationship.

[0065] Furthermore, in the developing device 6A, as shown in Figure 5, etc., the guide surface 74b, which is the surface opposite to the surface of the trimmer 74 that faces the outer peripheral surface of the developing roll 71, is configured in a curved shape such that the distance between it and the first adjustment member 76A gradually increases. For this reason, with this developing device 6A, compared to when the guide surface 74b of the trimmer 74 is not configured in a shape in which the distance from the first adjustment member 76A gradually increases, the excess developer 8f generated when the trimmer 74 passes through the fourth gap space E4, which separates the excess developer 8f from the developing roll 71, is more easily moved with less stress caused by friction with the guide surface 74b.

[0066] 5 and other drawings, the developing device 6A has a pickup magnetic pole N1 disposed on the magnet roll 71b of the developing roll 71, and is configured so that a peak MLp of the magnetic field lines ML of the pickup magnetic pole N1 is shifted upstream in the rotation direction B of the developing roll 71 from a terminal end 75ae of the inclined surface 75a of the movement auxiliary member 75. The peak MLp of the magnetic field lines ML is measured by a measuring device such as a magnetic flux density measuring device (MFD-04, manufactured by Clover Engineering Co., Ltd.). Therefore, with this developing device 6A, compared to a case where the peak MLp of the magnetic field lines ML of the pickup magnetic poles N3, N3 is not configured to be shifted upstream of the terminal end 75ae of the inclined surface 75a of the moving assist member 75 in the rotational direction B of the developing roll 71, the developer 8b moving through the first gap space E1 between the inclined surface 75a of the moving assist member 75 and the opposing surface 76a of the first adjustment member 76A can be moved and held in the developing roll 71 by receiving the transport force of the magnetic brush without falling from the terminal end 75ae of the inclined surface 75a of the moving assist member 75.

[0067] 7, the inclination of the second inclined surface 75a2, which is a portion close to the developing roll 71, may be gentler than the inclination of the first inclined surface 75a1, which is the remaining portion before reaching the portion close to the second inclined surface 75a2. The two-dot chain line HL in FIG. 7 indicates a horizontal line (plane).

[0068] In the developing device 6A configured in this manner, the stress applied to the developer 8b when moving it to the developing roll 71 can be reduced when passing over the second slope 75a2, which has a relatively gentle slope, compared to when passing over the first slope 75a1, in a case where the slope of the second slope 75a2, which is the portion close to the developing roll 71, is not gentler than the slope of the first slope 75a1, which is the remaining portion before reaching the nearby portion. Incidentally, the developer 8a that has moved from the first inclined surface 75a1 to the second inclined surface 75a2 has its sliding movement weakened due to the gentler slope, but because it is close to the developing roll 71, it is attracted by the magnetic force from the magnet roll 71b and moves toward the developing roll 71.

[0069] Second embodiment. FIG. 8 is a diagram showing a developing device 6B according to a second embodiment of the present invention. The developing device 6B of the second embodiment differs from the developing device 6A of the first embodiment in that the first screw auger 72 and the second screw auger 73 are arranged substantially horizontally, the first adjustment member 76A is changed to a first adjustment member 76B, and an intermediate transport roll 77, a second trimmer 78, a third screw auger 79, etc. are added; otherwise, the configuration is the same. For this reason, in the following description, the same reference numerals as in the first embodiment are used for the common components, and the description thereof will be omitted unless necessary.

[0070] In the developing device 6B, as shown in Figures 8 and 9, a first transport path 63 and a second transport path 64 are arranged in a substantially horizontal line in a storage section 62 in the lower part 60a of a housing 60, and a first screw auger 72 is rotatably arranged in the first transport path 63 and a second screw auger 73 is rotatably arranged in the second transport path 64.

[0071] 8, 10, 11, etc., the developing device 6B uses a cylindrical non-magnetic member as the first adjustment member 76B. For example, the surface portion of the curved outer circumferential surface of this cylindrical first adjustment member 76B indicated by the double arrow in FIG. 11 is used as an opposing surface 76a that faces the inclined surface 75a of the movement auxiliary member 75B and the surface portion of the developing roll 71 that has passed through the movement auxiliary member 75 at a distance.

[0072] Similarly to the first adjustment member 76A in the first embodiment, the first adjustment member 76B is attached to the lower part 60a or upper part 60b of the housing 60 or to a predetermined portion of a support frame (not shown) arranged therebetween, in a state in which the minimum distance J1 between the opposing surface 76a, which is the outer circumferential surface of the first adjustment member 76B, and the minimum distance J2 between the opposing surface 76a and the developing roll 71 are predetermined values. The first adjustment member 76B is also arranged so that the minimum distance J5 between the first adjustment member 76B and the intermediate transport roll 77 is a predetermined value.

[0073] 8, 10, 11, etc., the developing device 6B is provided with an intermediate transport roll 77, which is another example of a transport body that transports the developer 8 to be supplied to the developing roll 71. The intermediate transport roll 77 is disposed above the first screw auger 72 with a required interval therebetween, and is a member that holds a portion of the developer 8 transported forward by the first screw auger 72 and then intermediates and transports the developer 8 toward the developing roll 71.

[0074] The intermediate transport roll 77 is similar to the developing roll 71, and is composed of a cylindrical transport sleeve 77a that holds the developer 8 and rotates, and a magnet roll 77b that is fixedly arranged in the internal space of the transport sleeve 77a. The transport sleeve 77a is made of a non-magnetic material. The transport sleeve 77a is rotated in the direction indicated by the arrow C by the rotational power transmitted to the developing roll 71 or the first screw auger 72 being distributed. The magnet roll 77b has a plurality of magnetic poles (not shown) arranged on the surface of the transport sleeve 77a, which generate magnetic forces that perform functions such as attraction (pickup), holding and transporting, and peeling of the developer 8. Of these, the peeling magnetic pole is arranged in a portion of the magnet roll 77b slightly above the position facing the inclined surface 75a of the movement auxiliary member 75B.

[0075] The intermediate transport roll 77 is provided with a plate-shaped second trimmer 78, which is an example of a member for adjusting the amount (layer thickness) of developer 8 held by the transport sleeve 77a, on a portion of the transport sleeve 77a that is downstream of the first screw auger 72 in the rotational direction C. The second trimmer 78 is attached so that its tapered tip 78a faces the outer circumferential surface of the intermediate transport roll 77 (the transport sleeve 77a) at a required distance and in parallel with the direction of the rotation axis of the transport sleeve 77a.

[0076] The movement assist member 75B, like the movement assist member 75 in the first embodiment, is a non-magnetic member that is arranged between the intermediate transport roll 77 and the portion of the developing roll 71 upstream of the trimmer 74 in the rotational direction B, and has a slope 75a that receives the developer 8 sent from the intermediate transport roll 77 and moves it to the developing roll 71. In the second embodiment, the movement assist member 75B has a side lower portion 75d that is cut out and recessed toward the developing roll 71 below a side portion 75b on the side facing the relay transport roll 77 in order to ensure an arrangement space for the first screw auger 72. In addition, the movement assist member 75B has a side portion 75c on the side facing the developing roll 71 that extends to near the upper portion of the third screw auger 79 and is used as a part of the partition wall.

[0077] Furthermore, in the developing device 6B, as shown in Figures 8, 10, 11, etc., a third screw auger 79 is provided, which is an example of a third transport member that transports at least a portion of the developer 8e that is peeled off after passing through the development area Ed of the developing roll 71 so that it eventually flows back to the second transport path 64.

[0078] The third screw auger 79 is provided below the developing roll 71 in the lower part 60a of the housing 60 in a state parallel to the rotation axis of the developing roll 71, and is disposed in a third transport path 66 along which the developer 8e peeled off from the developing roll 71 is transported. As shown in Figures 8 and 9, the third transport path 66 is a groove-shaped portion in which a portion facing the portion of the developing roll 71 that peels off the developer 8 is opened and connected, and is connected via a third connection portion 69 that penetrates the first connection portion 67 in the first transport path 63 at a front portion of the downstream end in the third transport direction (depth direction Z in this example) along which the developer 8e is transported.

[0079] The third screw auger 79 is arranged so that a round rod-shaped rotating shaft 79a is rotated within the third transport path 66, and a forward transport blade 79b for forward transporting the developer 8e peeled off from the developing roll 71 in the third transport direction D5 is spirally wound around the round rod-shaped rotating shaft 79a at a predetermined height, inclination angle and pitch. Further, a plurality of plate-shaped conveying vanes 79c for sending the developer 8e to the first conveying path 63 adjacent to the first connection portion 67 are provided on the rotation shaft 79a of the third screw auger 79 in a state of rising from the rotation shaft 79a at a portion adjacent to the third connection portion 69. Further, the third screw auger 79 is provided such that reverse conveying vanes 79d for reverse conveying in a direction opposite to the third conveying direction D5 are spirally wound around a portion of the rotation shaft 79a on the downstream side in the third conveying direction D5 with respect to the plate-shaped conveying vanes 79c.

[0080] And also in this developing device 6B, similar to the case of the developing device 6A according to the first embodiment, as shown in FIG. 12, the minimum distance J1 between the inclined surface 75a of the movement assisting member 75 and the opposing surface 76a of the first adjusting member 76B, the minimum distance J2 between the opposing surface 76a of the first adjusting member 76B and the surface of the developing roll 71, and the minimum distance J3 between the surface of the plate-shaped trimmer 74 and the surface of the developing roll 71 are narrowed in this order.

[0081] Incidentally, in this developing device 6B, the minimum distance J5 between the first adjusting member 76B and the relay conveying roll 77 is set to a value larger than the minimum distance J1 between the inclined surface 75a of the movement assisting member 75B and the opposing surface 76a of the first adjusting member 76B (J5>J1). Also, the minimum distance J6 between the movement assisting member 75B and the relay conveying roll 77 is set to a value smaller than the above minimum distance J5 (J6<J5). Further, the minimum distance J7 between the side surface portion 75c of the movement assisting member 75B and the developing roll 71 is set to a value smaller than the minimum distance J2 between the opposing surface 76a of the first adjusting member 76 and the surface of the developing roll 71 (J7<J2).

[0082] This developing device 6B operates as follows.

[0083] When it is time for a developing operation or the like to be performed, as shown in FIG. 8, the developing sleeve 71a of the developing roll 71 starts to rotate in the direction indicated by the arrow B, and the conveying sleeve 77a of the relay conveying roll 77, the first screw auger 72, the second screw auger 73, and the third screw auger 79 start to rotate in the directions indicated by the respective arrows.

[0084] 8 and 9, in the second transport path 64, the developer 8 is transported forward in the second transport direction D2 while being agitated by the spiral forward transport blade 73b of the rotating second screw auger 73. The developer 8 transported forward to the downstream side of the second transport direction D2 of the second transport path 64 is sent to the first transport path 63 side while also receiving a reverse transport force from the spiral reverse transport blade 73d at the second connection portion 68, as illustrated by the dashed arrow D3 in FIG.

[0085] In the first transport path 63, the developer 8 is transported forward in the first transport direction D1 while being agitated by the spiral forward transport blade 72b of the rotating first screw auger 72. At this time, above the first transport path 63, a portion of the developer 8 being transported forward by the first screw auger 72 is held on the outer peripheral surface of the transport sleeve 77a of the intermediate transport roll 77 by magnetic force, and then transported by rotation of the transport sleeve 77a in the direction of arrow C. At this time, the developer 8 that is not held by the intermediate transport roll 77 and is transported forward by the first screw auger 72 is sent to the second transport path 64 side while also receiving a reverse transport force from the spiral reverse transport blade 72c at the first connection portion 67, as illustrated by the dashed arrow D4 in Figure 9.

[0086] Furthermore, in the intermediate transport roll 77, when the developer 8 held and transported on the transport sleeve 77a passes through the second trimmer 78, the passage of the surplus developer 8 is restricted by the second trimmer 78, and the amount held is adjusted. The surplus developer 8 falls back into the first transport path 63 and is transported forward in the first transport direction by the first screw auger 72, but some of it may be held by the intermediate transport roll 77 again. By making the second trimmer 78 return the excess developer 8 held on the intermediate transport roll 77 to the first transport path 63, the amount of developer 8 present in the portion of the first transport path 63 downstream in the first transport direction D1 is prevented from decreasing, and the amount is maintained to a certain extent.

[0087] Next, developer 8a, which is a part of the developer 8 held and transported by the intermediate transport roll 77 after passing through the second trimmer 78, is subjected to the magnetic force of the repulsive magnetic field of the peeling magnetic pole at a position before passing through the inclined surface 75a of the movement assist member 75B, and is peeled off from the surface of the transport sleeve 77a and sent to the developing roll 71 side, as shown in Figure 11.

[0088] 11, the developer 8a sent out from the relay transport roll 77 enters the first gap space E1 between the inclined surface 75a of the movement assist member 75B and the opposing surface 76a of the first adjustment member 76B. At this time, the developer 8 that does not enter the first gap space E1 is returned into the first transport path 63 and transported forward again by the first screw auger 72, or is transported while being held by the relay transport roll 77.

[0089] Next, as shown in FIG. 11, the developer 8b that has entered the first gap space E1 slides along the inclined surface 75a of the movement support member 75B while the amount passing through is restricted, and only the amount that has passed through reaches the outer peripheral surface of the developing sleeve 71a of the developing roll 71 and is held therein by the magnetic force from the magnet roll 71b, forming a spike-like magnetic brush. As a result, the amount of developer 8a moving to the developing roll 71 is adjusted.

[0090] Next, the developer 8c supplied to and held on the outer peripheral surface of the developing sleeve 71a is transported by, for example, the rotation of the developing sleeve 71a in the direction of arrow B, and passes through the second gap E2 between the first adjustment member 76B and the outer peripheral surface of the developing sleeve 71a, as shown in Fig. 11. At this time, the developer 8c moves while the amount passing through is limited by the second gap E2. As a result, the amount of developer 8c held on the outer peripheral surface of the developing sleeve 71a is adjusted once.

[0091] In addition, in the developing roll 71, the developer 8 that has passed through the second gap space E2 is transported in the direction indicated by the arrow B and passes through the trimmer 74. At this time, the developer 8 held on the outer peripheral surface of the developing sleeve 71a is caused to pass through the developing region Ed on the photosensitive drum 21 after the amount of developer held is adjusted by restricting the passage of excess developer 8 by the trimmer 74.

[0092] At this time, in the development area Ed, a part of the toner of the developer 8 held on the outer circumferential surface of the developing sleeve 71a of the developing roll 71 and transported adheres to the latent image portion on the photosensitive drum 21 by electrostatic force and is used to develop the latent image. After passing through the development area Ed, the developer 8e not used for development is subjected to the magnetic force of the repulsive magnetic field caused by the peeling magnetic pole of the magnet roll 71b in the storage section 62, and is separated from the developing sleeve 71a and sent to fall into the third transport path 66.

[0093] In the third transport path 66, as shown in Figures 8 and 9, the developer 8e that has been peeled off from the developing sleeve 71a and fallen is transported forward downstream in the third transport direction D5 by the forward transport blade 79b of the rotating third screw auger 79. The developer 8e conveyed forward to the downstream side of the third conveying path 66 in the third conveying direction D5 is conveyed to the first conveying path 63 by the plate-shaped conveying blade 79c at a portion adjacent to the third connecting portion 69. Next, the developer 8e conveyed to the first conveying path 63 is conveyed to the second conveying path 64 by the plate-shaped conveying blade 72d of the first screw auger 72, as illustrated by the arrow D6 in Fig. 9. Finally, the developer 8e conveyed to the second conveying path 64 is conveyed forward in the second conveying direction D2 by the second screw auger 73 and mixed with the developer 8 already present in the second conveying path 64.

[0094] In this developing device 6B, the first adjustment member 76B is provided and the three minimum intervals J1, J2, J3 are configured to satisfy the magnitude relationship J1>J2>J3. Therefore, the amount of developer 8 supplied from the intermediate transport roll 77 to the outer peripheral surface of the developing roll 71 and reaching the plate-shaped trimmer 74 is more stable than when this configuration is not used.

[0095] That is, in this developing device 6B, first, the amount of developer 8a supplied to the outer peripheral surface of the developing roll 71 is adjusted by passing the developer 8a sent from the relay transport roll 77 through the first gap space E1 between the inclined surface 75a of the movement support member 75B and the opposing surface 76a of the first adjustment member 76B. Next, in this developing device 6B, the developing roller 71 passes through a second gap space E2 between the opposing surface 76a of the first adjustment member 76B and the outer peripheral surface of the developing roller 71, which is set to a minimum gap J2 narrower than the minimum gap J1 of the first gap space E1. As a result, when the developer 8 is sent out from the intermediate transport roll 77 and then held on the outer circumferential surface of the developing roll 71 and reaches the trimmer 74, the developer 8 is supplied to the trimmer 74 with its held amount adjusted.

[0096] In addition, in the case of an image forming apparatus 1 using this developing device 6B, it is possible to prevent image quality defects such as blank streaks caused by instability in the amount of developer 8 in the developing device 6B before it reaches the trimmer 74.

[0097] In addition, the developing device 6B provides substantially the same operational effects as the developing device 6A according to the above-mentioned first embodiment. In this developing device 6B, as in the case of the developing device 6A according to the first embodiment, the inclination of the second inclined surface 75a2, which is the portion close to the developing roll 71, of the inclination surface 75a of the moving support member 75B may be configured to be gentler than the inclination of the first inclined surface 75a1, which is the remaining portion before reaching the portion close to the second inclined surface 75a2 (see FIG. 7).

[0098] Third embodiment. FIG. 13 is a diagram showing a developing device 6C according to a third embodiment of the present invention. When compared with the developing device 6B of the second embodiment, the developing device 6C of the third embodiment differs in that the fixed first adjustment member 76B is replaced with a first adjustment member 76C that is driven to rotate, but otherwise has the same configuration. For this reason, in the following description, the common components are denoted by the same reference numerals as in the first and second embodiments, and their description will be omitted unless necessary.

[0099] 13 and 14, the developing device 6C is configured such that, during operation, a cylindrical first adjustment member 76C is rotationally driven in the direction indicated by arrow D. That is, during operation of the developing device 6C, the first adjustment member 76C rotates in a direction in which it passes over the outer circumferential surface of the developing roll 71 after passing over the inclined surface 75a of the movement auxiliary member 75B. The movement assist member 75B is configured to rotate at the required speed in the direction of arrow D by distributing and transmitting the rotational power transmitted to the developing sleeve 71a of the developing roll 71 via a gear train mechanism not shown.

[0100] This developing device 6C basically operates in the same manner as the developing device 6B according to the second embodiment, and similarly provides the above-mentioned operational effects.

[0101] Furthermore, in this developing device 6C, as shown in Figure 14, the first adjustment member 76C is rotationally driven in the direction indicated by arrow D, so that when the developer 8a sent out from the intermediate transport roll 77 passes through the first gap space E1, or when the excess developer 8f due to adjustment of the trimmer 74 passes through the fourth gap space E4, a transport force is obtained by movement of the opposing surface 76a, which is the outer peripheral surface of the first adjustment member 76C, which is rotationally driven in the direction indicated by arrow D. Therefore, according to the developing device 6C, the movement of the developer 8 can be promoted compared to when the first adjustment member 76 is not rotationally driven in the above-mentioned direction, and as a result, for example, the surplus developer 8f is efficiently sent to the fourth gap space E4, and the amount of the developer sent increases. Also, the driving load when the developing sleeve 71a of the developing roll 71 is rotated is reduced. Furthermore, the stress applied to the developer 8 when passing through each gap space E1, E2, E4, etc. is also reduced.

[0102] Variations. The present invention is not limited to the contents exemplified in the first to third embodiments, and includes, for example, the following modified examples.

[0103] The developing device 6 may be, for example, a developing device in which the third screw auger 79 (including the associated third conveying path 66, etc.) in the developing device 6B in the second embodiment is added to the developing device 6A in the first embodiment.

[0104] In addition, in the developing devices 6B, 6C according to the second and third embodiments, as illustrated by the two-dot chain lines in Figures 8, 9 and 13, an injection port 82 for injecting replenishment developer 8 (mainly only toner) into the second conveying path 64 may be provided above the portion of the second conveying path 64 adjacent to the first connection portion 67, as illustrated by the two-dot chain lines in Figures 8, 9 and 13. Incidentally, when this injection port 82 is provided, even if a part of the developer 8 injected from the injection port 82 into the second transport path 64 enters the portion adjacent to the first connection portion 67 of the first transport path 63, the developer 8 that entered is sent so as to return to the second transport path 64 by the reverse transport blade 72c of the first screw auger 72. As a result, the developer 8 injected from the injection port 82 into the second transport path 64 is sent well into the second transport path 64 and transported forward in the second transport direction D2 while being agitated by the second screw auger 73.

[0105] The image forming apparatus is not limited to the image forming apparatus 1 having the configuration exemplified in the first embodiment, etc., and may be an image forming apparatus of any configuration as long as it is possible to apply the developing devices 6A, 6B, 6C, etc. exemplified in this invention. For example, the image forming apparatus may employ an image forming apparatus that employs an intermediate transfer method as the image forming device 2, or may employ an image forming apparatus capable of forming a multi-color image instead of a monochromatic image. The developing rotating body in the developing device is not limited to the developing roll 71 having a roll shape, and may be in a shape other than the roll shape, for example, in a belt shape. [Explanation of symbols]

[0106] 1. Image forming device 6A,6B,6C…Developing device 8... Developer 21...Photosensitive drum (an example of a latent image carrier) 71...Developing roll (an example of a developing rotating body) 72...First screw auger (an example of a supply conveying member) 74... Plate-shaped trimmer (an example of the second adjustment member) 77... Intermediate transport roll (an example of a supply transport member) 75...Movement support parts 75a...Slope 75a1: Near the developing roll 76A, 76B, 76C...First adjustment member 76a...Opposing surface B …Rotation direction of the developing roll C …Rotation direction of the supply transport member D … Rotation direction of the first adjustment member Ed…Development area J1, J2, J3...minimum spacing

Claims

1. a developing rotor that holds a magnetic developer and rotates to pass through a developing area; a supply and transport member that rotates to transport the developer to be supplied to the developing rotor; a non-magnetic movement assisting member disposed between the developing rotary body and the supply / transport member, the non-magnetic movement assisting member having a slope for receiving the developer sent from the supply / transport member and moving the developer to the developing rotary body; a first adjustment member having opposing surfaces facing, at an interval, the inclined surface of the movement assist member and the surface portion of the developing rotor that has passed through the movement assist member, and adjusting the amount of developer moved from the movement assist member to the developing rotor and the amount of developer held on the surface of the developing rotor; a second adjustment member disposed at an interval on a surface portion of the developing rotary body that has passed through the first adjustment member, and that adjusts an amount of developer held on the surface of the developing rotary body before the developer reaches the developing area; Equipped with the movement assist member is disposed such that the inclined surface is located above a virtual straight line connecting a rotation center point of the developing rotor and a rotation center point of the supply / conveyance member, A developing device in which the minimum gap between the inclined surface of the movement assist member and the opposing surface of the first adjustment member, the minimum gap between the opposing surface of the first adjustment member and the surface of the developing rotor, and the minimum gap between the second adjustment member and the surface of the developing rotor are narrowed in this order.

2. 2. The developing device according to claim 1, wherein the inclined surface of the movement auxiliary member and the opposing surface of the first adjustment member have a portion where the inclined surface of the movement auxiliary member and the opposing surface of the first adjustment member approach each other toward the developing rotary member, so as to reach the minimum gap.

3. 3. The developing device according to claim 1, wherein the inclination of the inclined surface of the movement auxiliary member in a portion close to the developing rotor is gentler than the inclination of the remaining portion before reaching the close portion.

4. 3. The developing device according to claim 1, wherein the opposing surface of the first adjustment member is formed of a curved surface that is convex toward the inclined surface of the movement auxiliary member and the surface of the developing rotor.

5. 5. The developing device according to claim 1, wherein the first adjustment member is a cylindrical member.

6. 6. The developing device according to claim 5, wherein the first adjustment member is rotationally driven in a direction passing over the surface of the developing rotor next to the opposing surface of the movement auxiliary member.

7. 7. A developing device according to claim 1, wherein the minimum distance between the portion of the second adjustment member that forms the minimum distance with the developing rotor and the opposing surface of the first adjustment member is wider than the minimum distance between the opposing surface of the first adjustment member and the surface of the developing rotor.

8. 8. The developing device according to claim 7, wherein the second adjustment member has a surface opposite to the surface facing the surface of the developing rotary body, the surface being configured so that the distance between the second adjustment member and the first adjustment member gradually increases.

9. The developing device according to any one of claims 1 to 8, wherein the developing rotor is composed of a rotating cylindrical member and a magnet member having a plurality of magnetic poles arranged inside the cylindrical member, and among the magnetic poles, a pickup pole is provided which magnetically holds the developer on the surface of the cylindrical member, and the peak of the magnetic field of the pickup pole is positioned upstream of the end of the inclined surface of the movement assist member in the direction of rotation of the developing rotor.

10. a latent image holder on which a latent image is held, and a developing device which develops the latent image on the latent image holder with a developer in a development area, An image forming apparatus, comprising the developing device according to claim 1 .

Images