Toner transport device, developing device equipped with the same, and image forming apparatus

Abstract

To provide a toner conveying device that can suppress stagnation of toner in a connection part at an upper end of a vertical conveying unit and a developing device including the same, and an image forming apparatus.SOLUTION: A toner conveying device comprises a vertical conveying unit, a horizontal conveying unit, a conveying member, and a loosening member. The vertical conveying unit causes a toner carried in from a carry-in port connected with a body-side conveyance path or a developer including toner to fall vertically and conveys the toner or the developer. The horizontal conveying unit is connected with a lower end part of the vertical conveying unit, and conveys the toner or the developer in a horizontal direction by the conveying member arranged inside the horizontal conveying unit. According to a bulk of the toner or the developer in the horizontal conveying unit, the loosening member is arranged at a first position below a connection part of the body-side conveyance path and the carry-in port and a second position projecting upward beyond the connection part. The toner conveying device can execute a toner loosening mode for feeding the toner or the developer to the vertical conveying unit to cause the loosening member to reciprocate at the second position.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a toner transport device that transports toner, and in particular to a toner transport device that has a toner transport section in which a horizontal transport section is connected to the lower end of a vertical transport section that drops toner vertically, and to a developing device and an image forming device that are equipped with the same. [Background technology]

[0002] An image forming apparatus such as an electrophotographic printer or copier includes a photosensitive drum that carries an electrostatic latent image, a developing device that supplies toner to the photosensitive drum to develop the electrostatic latent image into a toner image, and a toner container that replenishes the toner to the developing device. Color image forming apparatuses sometimes employ a layout in which an intermediate transfer unit is interposed between the toner container and the developing device. In this case, since the toner container and the developing device are spaced apart, a toner transport unit is provided that transports toner from the toner discharge port of the toner container to the toner receiving port of the developing device.

[0003] In this case, if the toner container can be placed directly above the developing device, the toner transport unit only needs to have a vertical transport unit that drops the toner vertically. However, if layout constraints make it difficult to place the toner container directly above the developing device, the toner transport unit needs to have a horizontal transport unit that transports the toner horizontally in addition to the vertical transport unit. The horizontal transport unit has a transport screw that transports the toner.

[0004] In a toner transport section where a horizontal transport section is connected to a vertical transport section, toner can aggregate near the bottom end of the vertical transport section (the connection with the horizontal transport path), which can prevent smooth toner replenishment. This occurs because the rotation of the transport screw pushes the toner near the bottom end of the vertical transport section back upward, causing the toner to aggregate and form clumps (blocking), which then clogs the transport path.

[0005] To solve the above problem, Patent Document 1 discloses a developer supply mechanism in which a coil spring is provided inside a developer supply passage that guides developer vertically. The coil spring extends while rotating by being caught on a first rib formed on the wall surface of the developer supply passage. When the coil spring is released from the first rib by the restoring force of the coil spring, the coil spring is given a horizontal movement away from the first rib.

[0006] Patent Document 2 discloses a powder conveying device including a first conveying section extending in a first direction and conveying powder by allowing it to fall under gravity, a second conveying section extending from one end to the other in a second direction different from the first direction and communicating with the first conveying section, a conveying member disposed within the second conveying section and including a shaft member extending in the direction of extension of the second conveying section and a protrusion provided around the shaft member, the conveying member conveying the powder from one end to the other by rotating about the axis of the shaft member, a powder disintegrating member disposed within the first conveying section so as to be swingable in the first direction, and a protective member attached to the lower end of the powder disintegrating member and in contact with at least the protrusion of the conveying member. The protective member and the powder disintegrating member swing in the first direction due to changes in the state of contact between the protective member and the protrusion caused by the rotation of the conveying member about the axis. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-256646 [Patent Document 2] International Patent Publication No. 2013 / 128844 Summary of the Invention [Problem to be solved by the invention]

[0008] In general, image forming apparatuses have a configuration in which the developing device is detachably installed in the image forming apparatus main body, which can cause toner accumulation (toner clogging) at the connection between the developing device and the image forming apparatus main body.

[0009] In the configurations of Patent Documents 1 and 2, a swinging spring is installed as a loosening member to loosen accumulated toner, but because the spring does not pass through the connecting portion, there is a problem in that it is not possible to prevent toner from accumulating at the connecting portion. Also, while it is conceivable to arrange the loosening member so that it passes through the connecting portion, if the conveying device is configured to be detachable from the image forming apparatus, the loosening member protruding from the connecting portion will interfere with the attachment and detachment of the conveying device.

[0010] In view of the above problems, the present invention aims to provide a toner transport device that can suppress toner aggregation in the vertical transport section of a toner transport section having a vertical transport section and a horizontal transport section, and can also suppress toner accumulation at the connecting section at the upper end of the vertical transport section, as well as a developing device and an image forming apparatus equipped with the same. [Means for solving the problem]

[0011] To achieve the above object, a first aspect of the present invention is a toner transport device detachably attached to an image forming apparatus, comprising a vertical transport unit, a horizontal transport unit, a transport member, and a loosening member. The vertical transport unit has an inlet at its upper end that connects to a main transport path of the image forming apparatus, and transports toner or developer containing toner transported through the inlet by vertically dropping it. The horizontal transport unit is connected to the lower end of the vertical transport unit and transports the toner or developer horizontally. The transport member includes a rotating shaft disposed within the horizontal transport unit along the toner or developer transport direction and a transport protrusion protruding from the outer circumferential surface of the rotating shaft. By rotating the rotating shaft, the transport protrusion transports the toner or developer in the horizontal transport unit in the direction of the rotation axis. The loosening member is disposed within the vertical transport unit so as to be vertically movable. The loosening member is disposed so as to be movable between a first position below the connection between the main transport path and the inlet and a second position that protrudes above the connection, and is vertically reciprocating between the first position and the second position. The loosening member is disposed at a first position by its own weight when the volume of toner or developer in the horizontal transport section is less than a predetermined value, and is pushed up by the toner or developer to a second position when the volume of toner or developer in the horizontal transport section is equal to or greater than a predetermined value. By feeding toner or developer into the vertical transport section, a toner loosening mode can be executed in which the loosening member reciprocates at the second position. [Effects of the Invention]

[0012] According to the first configuration of the present invention, the interior of the vertical transport section is placed in a state where the reciprocating movement of the loosening member performs a scraping operation, preventing toner or developer from clumping within the vertical transport section. Furthermore, the loosening member swings between a first position below the connecting portion and a second position penetrating the connecting portion upward, thereby preventing toner or developer from accumulating at the connecting portion between the main transport path and the inlet without interfering with the image forming apparatus's attachment / detachment to the main transport path. Furthermore, by feeding toner or developer into the vertical transport section, a toner loosening mode can be executed in which the loosening member reciprocates at the second position, thereby moving the loosening member to the second position at the desired timing to eliminate toner or developer accumulation at the connecting portion. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a schematic cross-sectional view of an image forming apparatus 100 equipped with developing devices 3a to 3d to which a toner supply unit 32 of the present invention is connected. [Figure 2] 1 is a perspective view of a developing device 3a mounted in an image forming apparatus 100. [Figure 3] Side cross-sectional view of developing device 3a [Figure 4] FIG. 1 is a side view of the developing device 3a as seen from the toner supply unit 32 side, showing a state in which the loosening member 50 is in the first position. [Figure 5] FIG. 1 is a vertical cross-sectional view of the toner supply unit 32 and the stirring and transport chamber 21 of the developing device 3a, showing a state in which the loosening member 50 is in a first position. [Figure 6] FIG. 1 is a side view of the release member 50 seen from the opening direction of the annular portion 53. [Figure 7] FIG. 10 is a side view showing another example of the unwinding member 50 having a different shape of the annular portion 53. [Figure 8] FIG. 10 is a side view of the developing device 3a as seen from the toner supply unit 32 side, showing the state in which the loosening member 50 is in the second position. [Figure 9] FIG. 10 is a vertical cross-sectional view of the toner supply unit 32 and the stirring and transport chamber 21 of the developing device 3a, showing a state in which the loosening member 50 is in the second position. [Figure 10] FIG. 1 is a block diagram showing an example of a control path of an image forming apparatus 100. [Figure 11] 1 is a flowchart showing an example of drive control of developing devices 3a to 3d in image forming apparatus 100. [Figure 12] FIG. 10 is a side view showing another example of the unwinding member 50 in which the first unwinding portion 51 and the second unwinding portion 52 have different shapes. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a cross-sectional view showing the internal structure of an image forming apparatus 100 equipped with developing devices 3a-3d to which a toner supply unit 32 (see Fig. 3) of the present invention is connected. Within the main body of the image forming apparatus 100 (here, a color printer), four image forming units Pa, Pb, Pc, and Pd are arranged in this order from the upstream side in the transport direction (left side in Fig. 1). These image forming units Pa-Pd are provided corresponding to images of four different colors (yellow, cyan, magenta, and black), and sequentially form images of yellow, cyan, magenta, and black through the processes of charging, exposure, development, and transfer, respectively.

[0015] These image forming stations Pa to Pd are provided with photosensitive drums (image carriers) 1a, 1b, 1c, and 1d that carry visible images (toner images) of each color. Additionally, an intermediate transfer belt (intermediate transfer member) 8 that rotates counterclockwise in FIG. 1 by a belt drive motor (not shown) is provided adjacent to each of the image forming stations Pa to Pd.

[0016] When image data is input from a host device such as a personal computer, the main motor 40 (see FIG. 10) first starts rotating the photosensitive drums 1a-1d. The charging devices 2a-2d then uniformly charge the surfaces of the photosensitive drums 1a-1d. The exposure device 5 then irradiates the photosensitive drums 1a-1d with light in accordance with the image data, forming electrostatic latent images on the photosensitive drums 1a-1d in accordance with the image data. The developing devices 3a-3d are filled with a predetermined amount of two-component developer containing yellow, cyan, magenta, and black toner, respectively. When the toner content of the two-component developer in each developing device 3a-3d falls below a predetermined value due to the formation of a toner image (described below), toner is replenished from the toner containers 4a-4d to each developing device 3a-3d. The toner in the developer is supplied to the photosensitive drums 1a-1d by the developing devices 3a-3d and electrostatically adheres to them. This results in the formation of a toner image corresponding to the electrostatic latent image formed by the exposure device 5.

[0017] Then, primary transfer rollers 6a to 6d apply an electric field at a predetermined transfer voltage between the primary transfer rollers 6a to 6d and the photosensitive drums 1a to 1d, and the black, yellow, magenta, and cyan toner images on the photosensitive drums 1a to 1d are primarily transferred onto the intermediate transfer belt 8. After the primary transfer, toner and the like remaining on the surfaces of the photosensitive drums 1a to 1d are removed by cleaning devices 7a to 7d.

[0018] The transfer paper P onto which the toner image is secondarily transferred is stored in a paper cassette 16 located at the bottom of the main body of the image forming apparatus 100, and is transported via a paper feed roller 12a and a pair of registration rollers 12b to the nip between the secondary transfer roller 9 and the drive roller 11 of the intermediate transfer belt 8. A blade-shaped belt cleaner 19 is located downstream of the secondary transfer roller 9 to remove toner and other particles remaining on the surface of the intermediate transfer belt 8.

[0019] The transfer paper P transported to the fixing unit 13 is heated and pressurized by the fixing roller pair 13a, and the toner image is fixed to the surface of the transfer paper P, forming a predetermined full-color image. The transfer paper P on which the full-color image has been formed is then transported in different directions by the branching unit 14, which branches into multiple directions, and is then discharged directly (or after being sent to the double-sided transport path 18 and having images formed on both sides) onto the discharge tray 17 by the discharge roller pair 15.

[0020] FIG. 2 is a perspective view of the developing device 3a mounted on the image forming apparatus 100. FIG. 3 is a side cross-sectional view of the developing device 3a. Note that FIG. 2 shows a state in which the cover member 20a of the developer container 20 and the developing roller 31 have been removed. In the following explanation, the developing device 3a arranged in the image forming section Pa of FIG. 1 will be exemplified, but the configurations of the developing devices 3b to 3d arranged in the image forming sections Pb to Pd are basically the same, so explanations will be omitted. The developing devices 3a to 3d are detachable from the image forming apparatus 100.

[0021] 2 and 3, the developing device 3a includes a developing container 20 that contains a two-component developer (hereinafter simply referred to as developer) containing a magnetic carrier and a toner. The developing container 20 includes a cover member 20a, a partition wall 20b, a first communicating portion 20c, a second communicating portion 20d, an agitating conveying chamber 21, a supplying conveying chamber 22, and a toner replenishing portion 32.

[0022] The cover member 20a is detachable from the main body of the developing container 20 and forms the upper part of the developing container 20. The partition wall 20b divides the interior of the developing container 20 into a stirring and conveying chamber 21 and a supply and conveying chamber 22, which are arranged in parallel. The first communication portion 20c and the second communication portion 20d communicate the stirring and conveying chamber 21 and the supply and conveying chamber 22 at both longitudinal ends of the partition wall 20b.

[0023] A mixing and conveying screw 25 and a supply and conveying screw 26 are rotatably disposed in the mixing and conveying chamber 21 and the supply and conveying chamber 22, respectively, for mixing the toner supplied from the toner container 4a (see FIG. 1) with the magnetic carrier, stirring and charging the toner. In this embodiment, a two-component developer consisting of positively charged toner and a ferrite-resin coated carrier is used.

[0024] The agitating and conveying screw 25 has a rotating shaft 25a and a first conveying blade 25b formed in a spiral shape at a constant pitch in the axial direction of the rotating shaft 25a. The rotating shaft 25a and the first conveying blade 25b are integrally molded from synthetic resin. The first conveying blade 25b extends to both longitudinal ends of the agitating and conveying chamber 21, extending to positions facing the first communicating portion 20c and the second communicating portion 20d. The rotating shaft 25a is rotatably supported by the first side wall portion 20f and the second side wall portion 20g of the developing container 20. The agitating and conveying screw 25 conveys the developer in the agitating and conveying chamber 21 in a constant direction (the direction of arrow A1) while agitating the developer.

[0025] The supply / conveyor screw 26 has a rotating shaft 26a and a second conveying blade 26b formed in a spiral shape at a constant pitch in the axial direction of the rotating shaft 26a. The rotating shaft 26a and the second conveying blade 26b are integrally molded from synthetic resin. The second conveying blade 26b has a length equal to or greater than the axial length of the developing roller 30 and extends to a position facing the first communicating portion 20c and the second communicating portion 20d. The rotating shaft 26a is disposed parallel to the rotating shaft 25a and is rotatably supported by the first side wall portion 20f and the second side wall portion 20g of the developing container 20. The supply / conveyor screw 26 conveys the developer in the supply / conveyor chamber 22 in the opposite direction (the direction of arrow A2) to the stirring / conveyor screw 25 while stirring the developer.

[0026] The developer is then stirred and transported in the axial direction (the direction perpendicular to the paper surface of FIG. 3) by the stirring and transport screw 25 and the supply and transport screw 26, and circulates between the stirring and transport chamber 21 and the supply and transport chamber 22 via the first communication portion 20c and the second communication portion 20d formed at both ends of the partition wall 20b. That is, a circulation path for the developer is formed inside the developing container 20 by the stirring and transport chamber 21, the first communication portion 20c, the supply and transport chamber 22, and the second communication portion 20d.

[0027] The developing container 20 extends diagonally upward to the right in Figure 3, and the developing roller 30 is disposed diagonally upward to the right within the developing container 20 of the supply / conveyor screw 26. A portion of the outer circumferential surface of the developing roller 30 is exposed through an opening 20e of the developing container 20 and faces the photosensitive drum 1a across a predetermined gap (development gap). The developing roller 30 rotates counterclockwise in Figure 3 (trail rotation at the position facing the photosensitive drum 1a).

[0028] The developing roller 30 is composed of a cylindrical developing sleeve that rotates counterclockwise in FIG. 3 and a magnet (not shown) with multiple magnetic poles fixed inside the developing sleeve. While a developing sleeve with a knurled surface is used here, other developing sleeves may be used, such as those with numerous dimples on the surface, those with blasted surfaces, those with blasted surfaces in addition to knurling and dimple formation, those plated for improved durability, those anodized, and those treated with a secondary electrolytic coloring method in which the porous portions of the anodized aluminum are treated with metal salts such as Ni, Sn, or Mo after anodizing. A developing voltage consisting of a DC voltage Vdc and an AC voltage Vac is applied to the developing roller 30 by a developing voltage power supply 73 (see FIG. 10).

[0029] A regulating blade 27 is attached to the developing container 20 along the longitudinal direction of the developing roller 30 (the direction perpendicular to the paper surface of FIG. 3). A small gap is formed between the tip of the regulating blade 27 and the developing roller 30. In this embodiment, a magnetic blade made of stainless steel (SUS430) is used as the regulating blade 27.

[0030] A toner concentration sensor 29 is disposed on the side of the stirring and conveying chamber 21, facing the stirring and conveying screw 25. The toner concentration sensor 29 detects the toner concentration in the developer in the developing container 20 (the mixture ratio of toner to carrier in the developer; T / C). As the toner concentration sensor 29, for example, a magnetic permeability sensor that detects the magnetic permeability of the two-component developer made up of toner and magnetic carrier in the developing container 20 is used. In accordance with the toner concentration detected by the toner concentration sensor 29, toner in the toner container 4a (see FIG. 1) is replenished into the developing container 20 via a toner replenishing unit 32.

[0031] Toner supply unit 32 is provided upstream of the developer transport direction (arrow A1 direction) within mixing transport chamber 21. Toner supply unit 32 includes toner supply port 33, vertical transport unit 34a, and horizontal transport unit 34b (see FIGS. 4 and 5). Toner supply port 33 opens at the top of toner supply unit 32 and is connected to main body transport path 40 (see FIG. 4) that extends downward from toner container 4a (see FIG. 1).

[0032] Fig. 4 is a side view of developing device 3a as seen from the toner supply unit 32 side. Fig. 5 is a vertical cross-sectional view of toner supply unit 32 and stirring / transport chamber 21 of developing device 3a. Fig. 6 is a side view of loosening member 50 arranged in vertical transport unit 34a of toner supply unit 32 as seen from the opening direction of annular portion 53.

[0033] 4, a drive input gear 63 is attached to the end of the developer container 20 on the toner supply unit 32 side. The drive input gear 63 inputs the drive force of a development drive motor 76 (see FIG. 10) to the stirring and conveying screw 25, the supply and conveying screw 26, and the development roller 30 of the development device 3a.

[0034] The vertical transport section 34a transports (drops) the toner carried in from the toner supply port 33 in the vertical direction. The horizontal transport section 34b extends horizontally below the vertical transport section 34a, receives the toner from the vertical transport section 34a, and transports it horizontally. The horizontal transport section 34b communicates with the agitation transport chamber 21 from the upstream side (left side in FIG. 5) with respect to the developer transport direction (arrow A1 direction) inside the agitation transport chamber 21.

[0035] The rotation shaft 25a of the agitating / conveying screw 25 passes through the second side wall portion 20g of the developing container 20 and extends into the horizontal conveying portion 34b of the toner replenishing portion 32. A supply blade 25c is formed integrally with the portion of the rotation shaft 25a located within the horizontal conveying portion 34b, and is spirally shaped at a constant pitch in the axial direction of the rotation shaft 25a. The supply blade 25c is formed by a spiral blade whose winding direction is the same as (in phase with) the first spiral blade 25b, and is formed with a smaller pitch and diameter than the first spiral blade 25b. In other words, the agitating / conveying screw 25 also serves as a conveying member that conveys the toner in the horizontal conveying portion 34b toward the agitating / conveying chamber 21.

[0036] The toner transported from the toner container 4a to the toner supply port 33 via the main body-side transport path 40 passes through the vertical transport section 34a and falls into the horizontal transport section 34b. The toner that has fallen into the horizontal transport section 34b is transported horizontally (to the right in FIG. 5) by the supply blade 25c of the stirring transport screw 25 and enters the stirring transport chamber 21 along the rotation shaft 25a. The toner is then stirred and mixed with the developer in the stirring transport chamber 21 (the developer that circulates from the supply transport chamber 22 through the second communication section 20d), and is thereby charged to a predetermined amount.

[0037] An unwinding member 50 is disposed in the vertical conveying section 34a. The unwinding member 50 is formed by bending a metal wire (spring material) and has a first unwinding portion 51 and a second unwinding portion 52 in the shape of a coil spring (coil spring), and an annular portion 53. The first unwinding portion 51 is disposed in an upper portion within the vertical conveying section 34a, with its upper end facing the toner supply port 33. The second unwinding portion 52 is disposed in a lower portion within the vertical conveying section 34a, with its lower end facing the supply blade 25c of the horizontal conveying section 34b. The outer diameters of the first unwinding portion 51 and the second unwinding portion 52 are formed to be smaller than the inner diameter of the vertical conveying section 34a.

[0038] The annular portion 53 has an elliptical shape that is long in the vertical direction, and the first unraveling portion 51 is connected to its upper end, and the second unraveling portion 52 is connected to its lower end. The annular portion 53 is fitted onto an eccentric rotation shaft 60 that protrudes horizontally within the vertical conveying portion 34a.

[0039] A protrusion 61 is formed on a portion of the outer circumferential surface of the eccentric rotation shaft 60. The eccentric rotation shaft 60 is rotated by the same drive source (development drive motor 76) as the stirring / conveying screw 25, the supply / conveying screw 26, and the developing roller 30. The inner diameter of the annular portion 53 is larger than the outer diameter of the eccentric rotation shaft 60, and the annular portion 53 and the eccentric rotation shaft 60 are engaged with each other with a predetermined gap (backlash) between them.

[0040] Fig. 7 is a side view showing another example of the unwinding member 50 having a different shape for the annular portion 53. The annular portion 53 may have any shape that opens horizontally, and may be rectangular as shown in Fig. 7, or may be polygonal, such as a hexagon. However, in order to allow the unwinding member 50 to smoothly reciprocate by rotation of the eccentric rotation shaft 60, an elliptical shape as shown in Fig. 6 or a rectangular shape with rounded corners on the inner circumferential surface as shown in Fig. 7 are preferred.

[0041] Next, the lifting and lowering operation of the unwinding member 50 will be described. Figures 4 and 5 show a state in which the unwinding member 50 is in a position (first position) close to the supply blade 25c. In the normal printing state, as shown in Figures 4 and 5, the toner in the horizontal transport section 34b does not come into contact with the second unwinding section 52. Therefore, the unwinding member 50 is supported by an eccentric rotation shaft 60. In addition, the first unwinding section 51 is located below the connecting section 41 between the toner supply port 33 and the main body transport path 40.

[0042] When the eccentric rotation shaft 60 rotates in this state, the protrusion 61 periodically comes into contact with and separates from the inner circumferential surface of the annular portion 53. More specifically, the protrusion 61 repeatedly comes into contact with the inner circumferential surface of the annular portion 53, lifting the annular portion 53, and the protrusion 61 separates, causing the annular portion 53 to descend under its own weight. As a result, the unwinding member 50 reciprocates up and down within the vertical conveying section 34a at a first position where the gap between the annular portion 53 and the eccentric rotation shaft 60 is below the eccentric rotation shaft 60. This constantly causes the reciprocating movement of the unwinding member 50 to perform a scraping operation within the vertical conveying section 34b, preventing toner from clumping within the vertical conveying section 34a.

[0043] Fig. 8 is a side view of developing device 3a seen from the toner supply unit 32 side, showing a state in which loosening member 50 is in the second position. Fig. 9 is a vertical cross-sectional view of toner supply unit 32 and stirring / transporting chamber 21 of developing device 3a, showing a state in which loosening member 50 is in the second position.

[0044] 8 and 9, when the amount of developer in the toner supply unit 32 increases, an upward force is exerted on the lower end of the second loosening portion 52 due to contact with the developer G. As a result, the loosening member 50 is lifted and moves to a second position where the gap between the annular portion 53 and the eccentric rotation shaft 60 is above the eccentric rotation shaft 60. When the loosening member 50 is in the second position, the first loosening portion 51 protrudes above the connecting portion 41 between the toner supply port 33 and the main body conveying path 40.

[0045] One method for increasing the amount of developer in the toner supply section 32 is to reversely rotate the agitating and conveying screw 25 of the developing device 3a, thereby reversing the rotation of the supply blade 25c formed on the agitating and conveying screw 25, thereby causing the developer in the agitating and conveying chamber 21 to flow back into the horizontal conveying section 34b and be sent to the toner supply section 32.

[0046] When the eccentric rotation shaft 60 rotates in this state, the protrusion 61 periodically comes into contact with and separates from the inner circumferential surface of the annular portion 53. More specifically, the state in which the protrusion 61 comes into contact with the inner circumferential surface of the annular portion 53, pushing down the annular portion 53, and the state in which the protrusion 61 separates, lifting the annular portion 53 up and down, are repeated. As a result, the unwinding member 50 reciprocates up and down within the vertical conveying section 34a at the second position.

[0047] As a result, the interior of the vertical conveying section 34a is brought into a state where the reciprocating movement of the loosening member 50 performs a scraping operation, thereby preventing toner from clumping inside the vertical conveying section 34a. Furthermore, by swinging the loosening member 50 at the second position where the first loosening section 51 penetrates the connecting section 41 upward, it is possible to prevent toner from accumulating (toner clogging) in the connecting section 41.

[0048] Therefore, toner can be smoothly and reliably replenished from the toner container 4a to the developing device 3a with a simple configuration. Also, it is possible to minimize the print waiting time (downtime) of the image forming apparatus 100 due to insufficient toner replenishment. Furthermore, because the loosening member 50 is normally disposed in the first position, the first loosening portion 51 does not interfere with the main body side conveyance path 40 when the developing device 3a is attached to or detached from the image forming apparatus 100, and the attaching and detaching operation of the developing device 3a can be performed smoothly.

[0049] Furthermore, since the loosening member 50 moves up and down reciprocatingly using the same drive source as the developing device 3a, no separate drive source is required to move the loosening member 50 reciprocatingly, and toner clumping (blocking) in the vertical conveying section 34a can be effectively suppressed with a simple configuration and at low cost.

[0050] Next, the control path of the image forming apparatus 100 of the present invention will be described. Fig. 10 is a block diagram showing an example of the control path used in the image forming apparatus 100 of the present invention. Note that, since various controls are performed on each section of the image forming apparatus 100 when it is used, the control path of the entire image forming apparatus 100 becomes complex. Therefore, the following description will focus on the parts of the control path that are necessary for implementing the present invention.

[0051] The control unit 90 includes at least a CPU (Central Processing Unit) 91 as a central processing unit, a ROM (Read Only Memory) 92 as a read-only memory unit, a RAM (Random Access Memory) 93 as a readable and writable memory unit, a temporary memory unit 94 that temporarily stores image data, etc., a counter 95 that accumulates and counts the number of printed sheets, and multiple (here, two) I / Fs (interfaces) 96 that send control signals to each device within the image forming apparatus 100 and receive input signals from the operation unit 60.

[0052] ROM 92 stores data such as a control program for image forming apparatus 100, numerical values ​​necessary for control, and data that will not be changed while image forming apparatus 100 is in use. RAM 93 stores necessary data that is generated during the control of image forming apparatus 100, data that is temporarily necessary for controlling image forming apparatus 100, and the like.

[0053] Furthermore, the control unit 90 transmits control signals from the CPU 91 to each part and device in the image forming apparatus 100 via the I / F 96. Furthermore, signals indicating the state of each part and device and input signals are transmitted from each part and device to the CPU 91 via the I / F 96. Examples of each part and device controlled by the control unit 90 include image forming units Pa to Pd, the exposure device 4, primary transfer rollers 6a to 6d, the secondary transfer roller 9, the image input unit 70, the voltage control circuit 71, the main motor 75, the development drive motor 76, the toner supply motor 77, the current detection unit 78, and the operation unit 80.

[0054] The image input unit 70 is a receiving unit that receives image data transmitted from a personal computer or the like to the image forming apparatus 100. The image signal input from the image input unit 70 is converted into a digital signal and then sent to the temporary storage unit 94.

[0055] Voltage control circuit 71 is connected to charging voltage power supply 72, developing voltage power supply 73, and transfer voltage power supply 74, and operates each of these power supplies in response to output signals from control unit 90. Each of these power supplies operates in response to control signals from voltage control circuit 71, with charging voltage power supply 72 applying a charging voltage to charging roller 21 in charging devices 2a to 2d. Development voltage power supply 73 applies a developing voltage, which is a DC voltage superimposed on an AC voltage, to developing roller 30 in developing devices 3a to 3d. Transfer voltage power supply 74 applies a predetermined primary transfer voltage and secondary transfer voltage to primary transfer rollers 6a to 6d and secondary transfer roller 9, respectively.

[0056] The toner supply motor 77 rotates the toner supply screw (not shown) in the toner container 4a to 4d, thereby supplying the toner stored in the toner container 4a to 4d to the toner supply section 32 of the developing device 3a to 3d via the main body side conveying path 40.

[0057] Current detection unit 78 detects the output current flowing through toner supply motor 77 when toner supply motor 77 is driven. The detection result is sent to control unit 90. If toner clogging occurs at connection portion 41 between main body transport path 40 and toner supply unit 32 (toner refill port 33), the accumulated toner generates a toner transport load, increasing the drive torque of toner supply motor 77 and therefore increasing the output current of toner supply motor 77. Control unit 90 can detect the occurrence of toner clogging at connection portion 41 by monitoring the output current value of toner supply motor 77 using current detection unit 78.

[0058] The operation unit 80 is provided with a liquid crystal display unit 81 and an LED 82 that indicates various states, and the user operates the stop / clear button on the operation unit 80 to stop image formation, and operates the reset button to reset various settings of the image forming apparatus 100 to their default states. The liquid crystal display unit 81 indicates the state of the image forming apparatus 100, as well as the image formation status and the number of copies to be printed. Various settings of the image forming apparatus 100 are made using the printer driver on the computer.

[0059] 11 is a flowchart showing an example of drive control of the developing devices 3a to 3d in the image forming apparatus 100. The execution procedure of the toner loosening mode executed in the developing devices 3a to 3d will be described along the steps of FIG. 11, with reference to FIGS. 1 to 10 as necessary.

[0060] The control unit 90 determines whether a print request has been received from a host device such as a personal computer (step S1). If a print request has not been received (No in step S1), the print standby state continues. If a print request has been received (Yes in step S1), a control signal is sent to the development drive motor 77 to start driving the development devices 3a to 3d (step S2). Then, at the same time as starting the image forming operation, the current detection unit 78 detects the output current I of the toner supply motor 77 (step S3).

[0061] The control unit 90 determines whether the output current I of the toner supply motor 77 is equal to or greater than a predetermined threshold value I1 (step S4). If I≧I1 (Yes in step S4), a toner blockage has occurred in the connection portion 41 between the main body transport path 40 and the toner supply portion 32 of one of the developing devices 3a-3d, and the image forming operation is interrupted (step S5). Then, the control unit 90 reverses the rotation of the development drive motor 76 to execute a toner loosening mode in which the developing device 3a-3d in which the toner blockage has occurred is driven in reverse (step S6).

[0062] When the developing devices 3a to 3d are driven to rotate in the reverse direction, the stirring and conveying screw 25 rotates in the reverse direction, and the replenishing blades 25c formed on the stirring and conveying screw 25 also rotate in the reverse direction. As a result, the developer in the stirring and conveying chamber 21 flows backward to the horizontal conveying portion 34b of the toner replenishing portion 32 and pushes up the loosening member 50 to the second position (see FIG. 8). In this state, when the eccentric rotating shaft 60 rotates in the reverse direction, the loosening member 50 reciprocates up and down at the second position, so that toner clogging at the connecting portion 41 can be eliminated.

[0063] The control unit 90 determines whether or not a predetermined time has elapsed since the start of the reverse rotation (step S7). If the predetermined time has elapsed (Yes in step S7), the reverse rotation drive of the developing devices 3a to 3d is stopped, the toner loosening mode is terminated (step S8), and the developing devices 3a to 3d are driven to rotate in the forward direction to resume the image forming operation (step S9). On the other hand, if I < I1 in step S4 (No in step S4), the image forming operation is continued without executing the toner loosening mode.

[0064] Thereafter, it is determined whether or not printing has ended (step S10). If printing is continuing (No in step S10), the process returns to step S3, the image forming operation and the detection of the output current I of the toner supply motor 77 are continued, and the following similar control is repeated (steps S3 to S9). If printing has ended (Yes in step S10), the process is terminated.

[0065] According to the control example shown in FIG. 11, when toner clogging at the connecting portion 41 is detected during image formation, the image forming operation is interrupted and the toner loosening mode is executed, so that the toner clogging can be quickly eliminated. As a result, toner supply shortage due to toner clogging at the connecting portion 41 does not occur, and the density of the output image can be maintained constant. Further, since toner clogging is detected based on the output current of the toner supply motor, a separate toner clogging detection mechanism is not required, and the number of parts and costs can be reduced.

[0066] The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present invention. For example, in the above-described embodiment, an unwinding member 50 including a first unwinding portion 51 and a second unwinding portion 52 each having a coil spring shape is illustrated. This is just one example, and as shown in FIG. 12, an unwinding member 50 may be used in which protrusions or ridges extend radially from a core member extending in the vertical direction as the first unwinding portion 51 and the second unwinding portion 52.

[0067] In the above embodiment, the stirring and conveying screw 25 is driven to rotate in the reverse direction to send the developer in the developing container 20 to the toner supply section 32, thereby moving the loosening member 50 to the second position, but the method of increasing the amount of developer in the toner supply section 32 is not limited to driving the stirring and conveying screw 25 to rotate in the reverse direction. For example, a bypass conveying path may be provided that connects the developing container 20 and the toner supply section 32, and the developer may be sent from the developing container 20 to the toner supply section 32 via the bypass conveying path when the loosening member 50 is moved to the second position.

[0068] In addition, in the above embodiment, toner clogging is detected based on the output current of the toner supply motor 77 detected by the current detection unit 78, but it is also possible to provide a torque detection mechanism that directly detects the rotational torque of the toner supply motor 77, and detect toner clogging based on the detection results of the torque detection mechanism.

[0069] Furthermore, in the above embodiment, a configuration has been described in which toner is replenished to the developing devices 3a to 3d in which the agitation transport chamber 21 and the supply transport chamber 22 are arranged in parallel, but a configuration in which toner is replenished to the developing devices 3a to 3d having the agitation transport chamber 21 and the supply transport chamber 22 arranged above the agitation transport chamber 21 has also been described. Furthermore, in the above embodiment, an example has been shown in which developer is supplied from the supply transport screw 26 to the developing roller 30, but the present invention is not limited to this. A developer carrier such as a magnetic roller may be further provided between the supply transport screw 26 and the developing roller 30, and after the developer is supplied from the supply transport screw 26 to the magnetic roller or the like, toner may be supplied from the magnetic roller or the like to the developing roller 30.

[0070] In the above embodiment, the toner supply unit 32 that supplies toner from the toner containers 4a to 4d to the developing devices 3a to 3d has been described. However, the toner transport device of the present invention is not limited to the toner supply unit 32 as long as a horizontal transport unit is disposed downstream of a vertical transport unit. For example, in a configuration in which an intermediate hopper that temporarily stores toner is provided between the toner containers 4a to 4d (see FIG. 1) and the developing devices 3a to 3d, the toner transport device of the present invention can be applied to a toner transport device that supplies toner from the toner containers 4a to 4d to the intermediate hopper. Alternatively, the toner transport device can be applied to a waste toner transport device that transports waste toner from the cleaning devices 7a to 7d (see FIG. 1) to a waste toner collection container (not shown).

[0071] Furthermore, the present invention is not limited to the tandem color printer shown in FIG. 1, but can also be applied to various image forming devices equipped with a toner transport device in which a horizontal transport section is located downstream of a vertical transport section, such as digital or analog monochrome copiers, monochrome printers, color copiers, and facsimiles. [Industrial Applicability]

[0072] The present invention can be used in a toner transport device having a vertical transport section and a horizontal transport section connected to the lower end of the vertical transport section. By using the present invention, it is possible to provide a toner transport device that can suppress toner aggregation in the vertical transport section of a toner transport section having a vertical transport section and a horizontal transport section, and can also suppress toner accumulation at the connecting section at the upper end of the vertical transport section, as well as a developing device and an image forming apparatus equipped with the toner transport device. [Explanation of symbols]

[0073] 3a~3d developing device 4a to 4d Toner container (toner storage section) 20 Developer container 25 Agitation conveying screw (agitation conveying member) 25a Rotating shaft 25c Supply blade (conveying member) 30 Developing roller 32 Toner supply unit (toner transport device) 33 Toner supply port (entrance) 34a Vertical conveyor 34b Horizontal conveyor 50 Release member 51 First loosening section 52 Second Unraveling Section 53 Annular section 60 Eccentric rotating shaft 61 protrusion 76 Development drive motor 77 Toner supply motor 78 Current detection unit (torque detection mechanism) 90 Control Unit 100 Image forming device

Claims

1. a vertical conveying section having an inlet connected to a conveying path on a main body side of the image forming apparatus at an upper end thereof, the vertical conveying section vertically dropping and conveying the toner or the developer containing the toner conveyed through the inlet; a horizontal transport section connected to a lower end of the vertical transport section and configured to transport the toner or the developer in a horizontal direction; a conveying member including a rotary shaft arranged in the horizontal conveying section along a conveying direction of the toner or the developer, and a conveying protrusion provided on an outer peripheral surface of the rotary shaft, the conveying member conveying the toner or the developer in the horizontal conveying section in the direction of the rotary shaft by rotating the rotary shaft with the conveying protrusion; a loosening member disposed in the vertical conveying section so as to be vertically movable; a toner conveying device detachably attached to the image forming apparatus, the loosening member is arranged to be movable between a first position below a connecting portion between the main body side transport path and the carry-in entrance and a second position protruding above the connecting portion, and is movable back and forth in a vertical direction between the first position and the second position, the loosening member is disposed at the first position by its own weight when the volume of the toner or the developer in the horizontal transport section is less than a predetermined value, and is pushed up by the toner or the developer to be disposed at the second position when the volume of the toner or the developer in the horizontal transport section is equal to or greater than a predetermined value, a toner conveying device capable of executing a toner loosening mode in which the loosening member reciprocates at the second position by feeding the toner or the developer to the vertical conveying portion;

2. 2. The toner transport device according to claim 1, wherein the transport member is driven to rotate in reverse, thereby causing the toner or developer in the horizontal transport section to flow back into the vertical transport section, and causing the unwinding member to move back and forth at the second position.

3. The loosening member is a first unraveling unit disposed in an upper portion of the vertical conveying unit and having an upper end facing the inlet; a second unraveling unit disposed below the vertical conveying unit and having a lower end facing the conveying member; an annular portion that connects the first unwinding portion and the second unwinding portion and engages with an eccentric rotation shaft that is horizontally protruding within the vertical conveying portion with a predetermined gap; and 3. The toner transport device according to claim 1, wherein the eccentric rotation shaft rotates while contacting the inner circumferential surface of the annular portion, thereby causing the loosening member to reciprocate vertically between the first position and the second position.

4. 4. The toner conveying device according to claim 3, wherein the first and second unwinding portions are in the shape of a coil spring, and the annular portion is in the shape of an ellipse or a rectangle with rounded corners on the inner circumferential surface.

5. 5. The toner transport device according to claim 3, wherein the eccentric rotation shaft is rotated by a common drive source together with the transport member.

6. a developer container in which the developer is stored; a stirring and conveying member that stirs and conveys the developer in the developing container; a developer carrier that is rotatably supported by the developing container and that carries the developer in the developing container, 6. A developing device comprising the toner transport device according to claim 1 as a toner supply section that supplies the toner to the developing container.

7. the conveying member and the agitating and conveying member share the same rotation shaft; The developing device according to claim 6, characterized in that the developer in the developing container is caused to flow back from the horizontal transport section of the toner supply section to the vertical transport section by rotating the transport member in the reverse direction together with the stirring transport member, thereby causing the unraveling member to move back and forth at the second position.

8. The developing device according to claim 7 ; a developing drive motor that drives the stirring and conveying member; a toner storage section that stores the toner to be supplied to the developing device; the main body side conveyance path connecting the toner storage unit and the toner supply unit; a toner supply motor that supplies the toner stored in the toner storage unit to the toner replenishing unit via the main body side transport path; a control unit that controls the developing drive motor and the toner supply motor; Equipped with The control unit is capable of executing a toner dissolving mode in which, when toner accumulation in the connecting portion is detected, the control unit causes the development drive motor to reversely rotate the transport member together with the stirring transport member, thereby causing the developer in the development container to flow back into the toner supply portion and moving the dissolving member back and forth at the second position.

9. a torque detection mechanism for detecting the rotational torque of the toner supply motor; 9. The image forming apparatus according to claim 8, wherein the control unit detects the accumulation of the toner at the connecting portion based on the rotational torque of the toner supply motor detected by the torque detection mechanism.

10. the torque detection mechanism is a current detection unit that detects an output current of the toner supply motor, 10. The image forming apparatus according to claim 9, wherein the control unit detects the accumulation of the toner in the connection portion based on the output current of the toner supply motor detected by the current detection unit.

Images