Powder conveying device and image forming device

Abstract

To provide a powder conveying device or an image forming apparatus that has increased toner conveyance efficiency.SOLUTION: A powder conveying device comprises: a first conveyance path; a second conveyance path that is connected to the first conveyance path; a first screw that is provided inside the first conveyance path and is rotated by first driving means to convey powder; and a second screw that is provided inside the second conveyance path and is rotated by second driving means to convey the powder conveyed by the first screw. The second screw has a rotation shaft and a spiral blade provided around the rotation shaft, and the first screw and the second screw are arranged such that a virtual line extending in the direction of the axis of rotation of the first screw intersects with the rotation shaft.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a powder transport device for transporting powder such as toner, and to an electrophotographic image forming apparatus, such as a printer, a copier, or a facsimile, that has a powder transport device. [Background technology]

[0002] Conventionally, an image forming apparatus using an electrophotographic method includes a toner storage unit that stores toner, a powder transport means that transports the toner stored in the toner storage unit, and an image forming unit to which the toner is transported by the powder transport means.

[0003] In the powder transport means for transporting toner, a spiral screw having a rotation axis at its center is disposed in the transport path, and is rotated to transport the toner from upstream to downstream of the transport path.

[0004] For example, a known configuration is one in which toner is dropped and transported from a toner bottle located vertically above to a developing device through a toner transport path via a toner supply port to a developing device (Patent Document 1). In this configuration, two screws are intersected to transfer toner from upstream to downstream. The transfer section is arranged so that the downstream end of the upstream screw and the upstream end of the downstream screw intersect vertically. When the toner transported by the upstream screw reaches the downstream end of the upstream screw, it is guided by gravity to the downstream screw, and then transported further downstream by the downstream screw. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-157350 Summary of the Invention [Problem to be solved by the invention]

[0006] In this way, the toner is transported by the transport force of the upstream screw, and then the toner is transferred from the upstream screw to the downstream screw using gravity acting on the toner. With this configuration, the transport force of the upstream screw to transport the toner is not utilized when the downstream screw transports the toner, which poses a problem in that the transport force cannot be increased sufficiently. [Means for solving the problem]

[0007] In order to achieve the above object, the powder conveying device of the present application is an image forming apparatus having a first cylindrical member through which toner is conveyed, a second cylindrical member through which toner flowing in from the first cylindrical member is conveyed upward, a first screw provided inside the first cylindrical member, the first screw having a first rotation axis and conveying the toner, and a second screw provided inside the second cylindrical member, the second screw having a second rotation axis and conveying the toner, wherein the first cylindrical member has a first end which is an end on the downstream side in the toner conveying direction of the first cylindrical member, and the second cylindrical member has a second end which is an end on the upstream side in the toner conveying direction of the second cylindrical member, the first screw further has a first helical blade provided around the first rotation shaft, and the second screw further has a second helical blade provided around the second rotation shaft, The first cylindrical member and the second cylindrical member are connected so that their interiors communicate only at the first end and the second end, and are arranged so that the rotation axis of the first rotation shaft of the first screw intersects with the end of the second rotation shaft of the second screw. 、 It is characterized by: [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a powder transport device or an image forming apparatus that improves the efficiency of transporting toner. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a diagram illustrating a toner conveying device according to the first embodiment. [Figure 2] FIG. 2 is a diagram illustrating a toner conveying device according to the first embodiment. [Figure 3]FIG. 1 is a diagram illustrating an image forming apparatus. [Figure 4] 10A and 10B are diagrams illustrating a toner transport device according to a modified example. [Figure 5] FIG. 10 is a diagram illustrating a toner conveying device according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] The following describes in detail exemplary embodiments of the present invention with reference to the drawings. However, the dimensions, materials, shapes, and relative positions of the components described in the embodiments may be changed as appropriate depending on the configuration of the device to which the invention is applied and various conditions. In other words, the scope of the present invention is not limited to the following embodiments. [Example]

[0011] In this embodiment, an electrophotographic, four-drum color image forming apparatus will be described. Here, the image forming apparatus is a device that forms a toner image based on image information input from an external device and transfers and fixes the toner image as a color image onto a recording material such as paper. Examples of image forming apparatuses include copiers, laser beam printers, and facsimile machines, but this embodiment will be described using a color laser beam printer as an example.

[0012] A process cartridge is a cartridge that integrates at least a developing means and a photosensitive drum, which is an electrophotographic photosensitive member, as a process means and is detachably mountable to the main body of an image forming apparatus. Here, the main body of the apparatus refers to the device components excluding at least the process cartridge from the configuration of the image forming apparatus.

[0013] In the following description, the right side when facing the image forming apparatus will be referred to as the right face of the image forming apparatus, and the left side when facing the image forming apparatus will be referred to as the left face of the image forming apparatus.

[0014] [Image forming device] FIG. 3 is a cross-sectional view showing a schematic configuration of the image forming apparatus according to this embodiment when viewed from the front side.

[0015] FIG. 3 shows a tandem type (or in-line type) color image forming apparatus in which four process cartridges 7a to 7d are arranged in a straight line.

[0016] Below the image forming apparatus 100, there is disposed a paper feed device 10 which is composed of a paper feed cassette 11 which stores recording material S, a paper feed roller 9, a separation means 23, and a pair of registration rollers 17 which sandwich and convey the recording material S. The paper feed cassette 11 is configured so that it can be pulled out from the image forming apparatus 100. Therefore, the user can replenish the recording material S by pulling out the paper feed cassette 11 from the image forming apparatus 100, setting the recording material S in the paper feed cassette 11, and then attaching it to the image forming apparatus 100.

[0017] Above the paper feed device 10, there is disposed one replenishing toner container 13 (13a to 13d) for replenishing toner (powder) to the process cartridges 7 (7a to 7d) of each color.

[0018] Above the replenishment toner container 13, an exposure unit 3 is arranged which irradiates the photosensitive drum 1 with a laser based on image information to form an electrostatic latent image on the photosensitive drum 1.

[0019] Four photosensitive drums 1 (1a to 1d) are provided above the exposure unit 3. Around each photosensitive drum 1, in the order of its rotation direction, there are provided a charging unit 2 (2a to 2d), a developing unit 4 (4a to 4d), a primary transfer roller 12 (12a to 12d), and a cleaning unit 8 (8a to 8d). The photosensitive drum 1, charging unit 2, developing unit 4, and cleaning unit 8 are each integrated into a cartridge, forming a process cartridge 7 (7a to 7d). Each process cartridge 7 is detachably mounted in the main body of the image forming apparatus 100, and in this embodiment, is configured to be detachably mounted on the front side of the image forming apparatus 100.

[0020] Each process cartridge 7 (7a to 7d) includes a cleaning unit 5 (5a to 5d) and a developing unit 4 (4a to 4d). A supply toner container 13 (13a to 13d) that is detachably mounted on the main body of the image forming apparatus 100 can be connected to each developing unit 4 (4a to 4d) so that toner can be replenished. These four process cartridges 7 (7a to 7d) and supply toner containers 13 (13a to 13d) have the same structure, but differ in that they form images of different colors using yellow (Y), magenta (M), cyan (C), and black (Bk) toner.

[0021] The cleaning unit 5 (5a to 5d) has a photosensitive drum 1 (1a to 1d), a charging section 2 (2a to 2d), and a cleaning section 8 (8a to 8d).

[0022] The photosensitive drums 1 (1a to 1d) are made by coating the outer circumferential surface of an aluminum cylinder with an organic photoconductor layer (OPC), and are rotatably supported at both ends by flanges. By transmitting a driving force from a driving motor to one end of the photosensitive drums 1 (1a to 1d), the photosensitive drums 1 (1a to 1d) are rotated in the clockwise direction indicated by the arrow in FIG. 3.

[0023] The charging unit 2 (2a to 2d) is a conductive roller formed in the shape of a roller, which is brought into contact with the surface of the photosensitive drum 1 (1a to 1d) and is capable of uniformly charging the surface of the photosensitive drum 1 (1a to 1d) by applying a charging voltage from a power source.

[0024] The cleaning sections 8 (8a to 8d) are capable of removing toner from the surfaces of the photosensitive drums 1 (1a to 1d) by coming into contact with the photosensitive drums 1 (1a to 1d). The toner (waste toner) removed by the cleaning sections 8 (8a to 8d) in the cleaning units 5 (5a to 5d) is configured to be stored in a toner recovery container 26 provided above.

[0025] On the other hand, the developing units 4 (4a to 4d) have developing rollers 24 (24a to 24d). The developing units 4 (4a to 4d) contain toner of each color, yellow (Y), magenta (M), cyan (C), and black (Bk), which are supplied from supply toner containers 13 (13a to 13d). The developing rollers 24 (24a to 24d) are disposed adjacent to the surfaces of the photosensitive drums 1 (1a to 1d) and are configured to be rotated by a drive unit and to develop the latent images on the surfaces of the photosensitive drums 1 (1a to 1d) with toner when a voltage is applied.

[0026] An intermediate transfer unit 12, which is an intermediate transfer body, is disposed above the process cartridges 7 (7a to 7d). In this embodiment, the image forming section includes the process cartridges 7 (7a to 7d) that form toner images of each color, and the intermediate transfer unit 12 onto which the toner images of each color are sequentially transferred to form a color toner image.

[0027] The intermediate transfer unit 12 is composed of an intermediate transfer belt (intermediate transfer body) 12e, a drive roller 12f, a driven roller 12g, primary transfer rollers 12 (12a to 12d), and a cleaning device 22, which serves as a cleaning section. The intermediate transfer belt 12e is an endless cylindrical belt that is stretched over the drive roller 12f and the driven roller 12g. The driven roller 12g is biased by a biasing means to apply a predetermined tension to the intermediate transfer belt 12e. The drive roller 12f is driven to rotate by a motor or the like, causing the intermediate transfer belt 12e to rotate at a predetermined speed. Each primary transfer roller 12 (12a to 12d) is disposed inside the intermediate transfer belt 12e, facing each photosensitive drum 1 (1a to 1d), and the primary transfer rollers 12 and the photosensitive drums 1 form a primary transfer section. Further, the drive roller 12f is disposed so as to face the secondary transfer member 16 via the intermediate transfer belt 12e, and the drive roller 12f and the secondary transfer member 16 form a secondary transfer section 15. The cleaning device 22 cleans the toner (waste toner) that has not been secondary transferred from the intermediate transfer belt 12e. The toner removed by the cleaning device 22 is stored in a toner recovery container 26 provided above the cleaning device 22.

[0028] Furthermore, a fixing device 25 is disposed above the secondary transfer section 15 of the intermediate transfer unit 12. The fixing device 25 is mainly composed of a heating element 25a and a pressure roller 25b. The heating element 25a rotates around the heating element, and the outer peripheral surface of a fixing film made of an endless cylindrical belt heated by the heating element is disposed on the toner image surface side of the recording material S. The pressure roller 25b is driven to rotate by a driving means, and the fixing film of the heating element 25a, which is pressed against the pressure roller 25b, rotates accordingly, forming a fixing nip between the heating element 25a and the pressure roller 25b.

[0029] Further, downstream of the fixing device 25 in the conveyance direction of the recording material S, a pair of discharge rollers 20 and a discharge tray 21 are disposed. The discharge tray 21 is a stacking portion that forms the top surface of the image forming apparatus 100 and stacks multiple sheets of recording material S, and has an inclined surface 21a that is inclined with respect to the horizontal. The inclined surface 21a is inclined in a direction in which the pair of discharge rollers 20 side is lowered, and the discharge tray 21, which is a stacking portion, is provided with the inclined surface 21a in order to maintain the alignment of the recording materials S even when subsequent recording materials S are discharged while multiple sheets of recording material S are stacked on the discharge tray 21. As a result, the discharged recording materials S are stacked on the discharge tray 21, which is a stacking portion, while maintaining their alignment, without pushing out the stacked recording materials S.

[0030] [Image formation process] First, the surfaces of the photosensitive drums 1 (1a to 1d) are uniformly charged by the charging units 2 (2a to 2d), and then the exposure unit 3 irradiates each photosensitive drum 1 (1a to 1d) with a laser based on image information, forming an electrostatic latent image on the surface of each photosensitive drum 1 (1a to 1d). The electrostatic latent image formed on the surface of each photosensitive drum 1 (1a to 1d) is developed by the respective development units 4 (4a to 4d) to form a toner image. The toner images formed on the surface of each photosensitive drum 1 (1a to 1d) are transferred and carried sequentially in layers onto the intermediate transfer belt 12e by applying a voltage to the primary transfer rollers 12 (12a to 12d), and are transported to the secondary transfer unit 15. After the primary transfer, the toner (waste toner) remaining on the photosensitive drum 1 is removed by the cleaning unit 8 and transported to a toner recovery container 26 disposed within the image forming apparatus 100. On the other hand, the paper feed roller 9 is in pressure contact with the recording material S stored in the paper feed cassette 11, and rotates at a predetermined controlled timing to feed the recording material S, which is then separated and fed one sheet at a time by a separating means 23. Thereafter, the recording material S is conveyed to the secondary transfer unit 15 by a pair of registration rollers 17.

[0031] At the secondary transfer section 15, a bias is applied to the secondary transfer member 16, and the toner image on the intermediate transfer belt 12e is transferred onto the conveyed recording material S. After the secondary transfer, the toner (waste toner) remaining on the intermediate transfer belt 12e is removed by a cleaning device 22, which is a cleaning section, and conveyed to a toner recovery container 26 disposed inside the image forming apparatus 100. The recording material S conveyed from the secondary transfer section 15 is sandwiched and conveyed between a heating element 25a and a pressure roller 25b of a fixing device 25, and the toner image is heat-fixed onto the recording material S. The recording material S with the fixed toner image is then sandwiched and conveyed between a pair of discharge rollers 20, and discharged to a discharge tray 21.

[0032] [Toner transport device] 1 shows the detailed configuration of the toner transport device (powder transport device) 14 (14a to 14d) that transports toner from the supply toner container 13 (13a to 13d) to the developing units 4 (4a to 4d) of the process cartridges 7 (7a to 7d). The toner transport device 14 is broadly composed of an upstream transport path (first transport path) 101 that transports toner in the horizontal direction, and a downstream transport path (second transport path) 102 that transports toner in the vertical direction.

[0033] An upstream screw (first screw) 103 having a rotating shaft 103a and a spiral blade 103b disposed around the rotating shaft 103a is disposed inside the upstream transport path 101. A hole 104 is disposed in the upper surface of the upstream transport path 101. Toner in the replenishment toner container 13 is supplied from a supply port provided in the replenishment toner container 13 so as to drop through the hole 104 onto the upstream screw 103 in the upstream transport path 101. A drive gear 105, to which a rotational force is input from a drive source (first drive means) such as a motor (not shown), is disposed at the end of the upstream screw 103 opposite the downstream transport path 102 with respect to the hole 104. The upstream screw 103 is thus rotated and driven by the drive gear 105. In this manner, the upstream screw 103 is configured to transport toner supplied to one end of the upstream screw 103 through the hole 104 to the downstream transport path 102 disposed at the other end of the upstream screw 103 in the upstream transport path 101.

[0034] A downstream screw (second screw) 106 having a rotation shaft 106a and a spiral blade 106b provided around the rotation shaft 106a is disposed inside the downstream transport path 102. An end portion located vertically below the downstream transport path 102 is connected to an end portion downstream of the upstream transport path 101 in the toner transport direction, so that toner transported by the upstream transport path 101 is transported to the downstream screw 106. A drive gear 107 is provided at one end vertically below the downstream screw 106, to which a rotational force is input from a drive source (second drive means) such as a motor (not shown), and the downstream screw 106 is rotated by the drive gear 107. As a result, the downstream screw 106 is configured to transport toner supplied from the other end of the upstream screw 103 to the developing units 4 (4a to 4d) in the downstream transport path 102.

[0035] In this case, the upstream screw 103 (rotation shaft 103a) is disposed so that an imaginary line extending in the direction of its rotation axis intersects with the rotation axis of the downstream screw 106 (rotation shaft 106a). When a vector extending from the downstream side of the upstream screw 103 to the upstream side and a vector extending from the upstream side of the downstream screw 106 to the downstream side are defined, the angle between the smaller of the two vectors is set to 90 degrees in this embodiment. However, this is not limited to this, and any angle less than 90 degrees may be used. Additionally, in this embodiment, the upstream screw 103 and the downstream screw 106 have the same diameter d (mm) of their rotation shafts 103a and 106a. Therefore, the upstream screw 103 and the downstream screw 106 are disposed so that the outline of the rotation shaft 103a projected in the axial direction of the upstream screw 103 completely overlaps with the rotation shaft 106a of the downstream screw 106 (FIG. 2(a)).

[0036] As a result, the toner, to which the conveying force is transmitted by the blade 103b of the upstream screw 103, can be further conveyed by the blade 106b of the downstream screw 106, which is located at the destination of the conveyed toner. In other words, the conveying force obtained by the upstream screw 103 can also be utilized when conveying the toner by the downstream screw 106. With this configuration, the pressure applied to the toner by the upstream screw 103 is efficiently used to convey the toner by the downstream screw 106, thereby improving the toner conveying efficiency of the toner conveying device 14. In particular, when conveying toner vertically upward against gravity in the downstream conveying path 102, if the interior of the downstream conveying path 102 is not filled with toner, the toner will flow back due to gravity. However, in this embodiment, the conveying force of the upstream screw 103 is utilized to generate sufficient inflow pressure to convey the toner against gravity through the downstream conveying path 102.

[0037] In this embodiment, the upstream screw 103 and the downstream screw 106 have the same diameter d (mm) of the rotary shafts 103a and 106a, but this is not limited to this. If the rotary shafts 103a and 106a have different diameters, it is sufficient that an imaginary line extending in the axial direction of the upstream screw 103 overlaps with the rotary shaft 106a. In other words, it is sufficient that the outline of the rotary shaft 103a projected in the axial direction of the upstream screw 103 at least partially overlaps with the rotary shaft 106a of the downstream screw 106. Even in this case, the toner transport efficiency of the toner transport device 14 can be improved.

[0038] In this embodiment, at the other end of the upstream screw 103 adjacent to the downstream transport path 102, a blade 103b is provided around the rotation shaft 103a all the way to the other end of the upstream screw 103. This allows the transport force applied to the toner by the upstream screw 103 to be transmitted to the downstream transport path 102. To achieve this configuration, in this embodiment, at the other end of the upstream screw 103, the blade 103b of the upstream screw 103 is in sliding contact with the inner wall surface 203 of the upstream transport path 101 to support the upstream screw 103 (FIG. 2(b)). Specifically, in a direction perpendicular to the rotation axis of the rotation shaft 103a, the entire outer periphery of the blade 103b farthest from the rotation shaft 103a or a portion thereof positioned vertically below the outer periphery slides and contacts the inner wall surface 203 of the upstream transport path 101 to support the upstream screw 103. This allows the blades 103b of the upstream screw 103 to apply a transport force to the toner right up to the downstream screw 106 without interfering with the transport of the toner at the support portion of the upstream screw 103. As a result, the toner transport efficiency of the toner transport device 14 can be further improved.

[0039] Generally, two methods for increasing the toner transport volume are available: increasing the screw outer diameter to increase the volume of the transport path, and increasing the screw rotation speed. Both methods increase the volume of the screw moving per unit time, thereby increasing the transport volume. However, increasing the screw rotation speed increases power consumption and operating noise, while increasing the screw outer diameter to increase the volume of the transport path results in problems such as an increase in the size of the device. However, the configuration of this embodiment allows the transported toner to be efficiently transferred to the downstream screw at the transfer section using the transport force of the upstream screw. Therefore, the screw rotation speed can be minimized relative to the required toner transport volume, thereby achieving power savings and low noise. Similarly, minimizing the screw outer diameter relative to the required toner transport volume allows the overall device to be made smaller.

[0040] In this embodiment, the upstream screw and the downstream screw have the same parameters, but the present invention is not limited to this. Examples of parameters include the screw outer diameter, the central shaft outer diameter, the screw rotation speed, and the screw pitch, but the effect can be obtained regardless of the combination of screws with different parameters.

[0041] <Modification> In the first embodiment, the present invention is applied to the toner transport device 14 that transports the toner used for development from the supply toner container 13 to the development unit 4 of the process cartridge 7. However, the present invention is not limited to this, and may be applied to a configuration that transports the toner (waste toner) removed by the cleaning section 8 of the cleaning unit 5 to be stored in the toner recovery container 26.

[0042] Furthermore, while the first embodiment uses the upstream screw 103 having a rotating shaft 103a and a spiral blade 103b disposed around the rotating shaft 103a, the present invention is not limited to this. For example, as shown in FIG. 4, the upstream screw 103 may be configured to have no rotating shaft but only blades formed by spirally wound wire, such as piano wire. In this case, the upstream screw 103 may be disposed so that an imaginary line extending in the direction of the rotation axis of the upstream screw 103 (not shown) passes through the rotation axis 106a of the downstream screw 106. More preferably, the rotation axis of the upstream screw 103 and the rotation axis of the downstream screw 106 (rotation axis 106a) intersect with each other. Even in this case, the toner conveying efficiency of the toner conveying device 14 can be improved, and the same effects as those of the first embodiment can be obtained. [Example]

[0043] A second embodiment of the present invention will be described below. In the first embodiment, toner transported by upstream transport path 101 is supplied to a lower end of downstream transport path 102 extending in the vertical direction, and is transported by downstream screw 106. However, the present invention is not limited to this. Alternatively, toner transported by the upstream transport path may be supplied to a center of the downstream transport path extending in the vertical direction, and is transported by a downstream screw provided in the downstream transport path. Specifically, as shown in FIG. 5, the present invention may be applied to a toner transport device 50 that collects toner (waste toner) remaining on intermediate transfer belt 12e that has not been transferred at secondary transfer unit 15 using cleaning device 22, and transports the toner from toner transport path 55 to toner transport path 53.

[0044] In toner transport device 50, toner (waste toner) that is not transferred at the primary transfer unit and remains on photosensitive drum 1 is collected by cleaning unit 8, transported in the order of toner transport paths 51 (51a to 51d), 52, 53, and 54, and stored in toner recovery container 26. Therefore, the toner collected at the primary transfer unit and the secondary transfer unit join together at transfer section 508 from upstream transport path 55 to downstream transport path 53, and is transported from toner transport path 53 to toner recovery container 26 via toner transport path 54.

[0045] The toner transport device 50 according to the second embodiment will be described below with reference to Fig. 5. Fig. 5(a) is a detailed view of the toner transport device for transporting toner according to the second embodiment, showing the configuration between the toner transport path 53 and the toner recovery container 26. Fig. 5(b) shows the screw disposed inside the toner transport device shown in Fig. 5(a) and its drive configuration.

[0046] The toner remaining on the intermediate transfer belt 12e that was not transferred at the secondary transfer section 15 is collected by the cleaning device 22, and then the collected toner is transported from the front side to the back side of the image forming device 100 and supplied through a hole 505 provided in the upstream transport path 55.

[0047] An upstream screw 506 having a rotating shaft 506a and a spiral blade 506b provided around the rotating shaft 506a is disposed inside the upstream transport path 55. The toner collected by the cleaning device 22 is supplied through the hole 505 so as to fall onto the upstream screw 506 in the upstream transport path 55. A drive gear 507, to which a rotational force is input from a drive source (first drive means) such as a motor (not shown), is disposed at the end of the upstream screw 506 opposite the downstream transport path 53 with respect to the hole 505, and the upstream screw 506 is rotated by the drive gear 507. In this way, the upstream screw 506 is configured to transport the toner supplied to one end of the upstream screw 506 through the hole 505 to the downstream transport path 53 located at the other end of the upstream screw 506.

[0048] A downstream screw 501 having a rotation shaft 501a and a spiral blade 501b provided around the rotation shaft 501a is disposed inside the downstream transport path 53. The downstream transport path 53 extends vertically and is connected to the downstream end of the upstream transport path 55 in the toner transport direction, so that the toner transported by the upstream transport path 55 is transported to the downstream screw 501. A drive gear 502 to which a rotational force is input from a drive source (second drive means) such as a motor (not shown) is provided at one end below the downstream screw 501, and the downstream screw 501 is rotatable by the drive gear 502.

[0049] On the other hand, toner remaining on the photosensitive drum 1 (1a to 1d) that was not transferred in the primary transfer is collected by the cleaning section 8, and is transported through the cleaning unit 5 in the vertical direction by the toner transport path 51 (51a to 51d) and in the horizontal direction by the toner transport path (third transport path) 52. The toner transport path 52 is connected to the downstream transport path 53 between the transfer section 508 from the upstream transport path 55 to the downstream transport path 53 and the drive gear 502. In other words, the toner remaining on the photosensitive drum 1 that was not transferred in the primary transfer section is configured to be delivered to the downstream transport path 53 via the toner transport paths 51 (51a to 51d) and 52.

[0050] Therefore, when drive gear 502 is driven, downstream screw 501 transports waste toner from the primary transfer unit delivered by toner transport path 52 and waste toner from the primary transfer unit delivered from upstream screw 506 of upstream transport path 55. The toner transported by downstream screw 501 is then transported to toner recovery container 26 via toner transport path 54 at the downstream (vertically upper) end of downstream screw 501. Toner transport path 54 has screw 504 therein, which includes a rotation shaft and a spiral blade provided around the rotation shaft. Screw 504 is rotationally driven by drive gear 503 connected to screw 504, and is configured to be able to transport waste toner from the primary transfer unit and the secondary transfer unit to toner recovery container 26.

[0051] In this embodiment, the upstream screw 506 (rotation shaft 506a) is disposed so that an imaginary line extending in the direction of its rotation axis intersects with the rotation axis of the downstream screw 501 (rotation shaft 501a). When a vector extending from the downstream side of the upstream screw 506 to the upstream side and a vector extending from the upstream side of the downstream screw 501 to the downstream side are defined, the angle between the smaller of the two vectors is set to 90 degrees in this embodiment. However, this is not limited to this, and any angle less than 90 degrees may be used. Additionally, in this embodiment, the upstream screw 506 and the downstream screw 501 have the same diameter d (mm) of their rotation axes 506a, 501a. Therefore, the upstream screw 506 and the downstream screw 501 are disposed so that the outline of the rotation axis 506a projected in the direction of the rotation axis of the upstream screw 506 completely overlaps with the rotation axis 501a of the downstream screw 501.

[0052] This allows the toner, to which the transport force has been transmitted by blade 506b of upstream screw 506, to continue to be transported by blade 501b of downstream screw 501, which is located at the destination of the transport. In other words, the transport force obtained by upstream screw 506 can also be utilized when transporting the toner by downstream screw 501. With this configuration, the pressure applied to the toner by upstream screw 506 is efficiently used to transport the toner by downstream screw 501, thereby improving the toner transport efficiency of toner transport device 50.

[0053] Furthermore, when the downstream screw 501 transports toner vertically upward against gravity, the toner will flow backward due to gravity unless the inside of the downstream transport path 53 is filled with toner. On the other hand, in a configuration where toner transported from the toner transport path 55 joins, it is necessary to make it possible for the waste toner from the secondary transfer unit to be inserted into the waste toner from the primary transfer unit that is already inside the toner transport path 53. Therefore, the toner transport device 50 utilizes the transport force of the upstream screw 506 of the toner transport path 55 to transport the toner in the downstream transport path 53.

[0054] In this embodiment, the upstream screw 506 and the downstream screw 501 have the same diameter d (mm) of the rotation shafts 506a, 501a, but this is not limited to this. If the diameters of the rotation shafts 506a, 501a are different, it is sufficient that an imaginary line extending in the rotation axis direction of the upstream screw 506 overlaps with the rotation shaft 501a. In other words, it is sufficient that the outline of the rotation shaft 506a projected in the rotation axis direction of the upstream screw 506 at least partially overlaps with the rotation shaft 501a of the downstream screw 501. Even in this case, the toner transport efficiency of the toner transport device 50 can be improved.

[0055] In this embodiment, at the other end of the upstream screw 506 adjacent to the downstream transport path 53, a blade 506b is provided around the rotation shaft 506a all the way to the other end of the upstream screw 506. This allows the transport force applied to the toner by the upstream screw 506 to be transmitted to the downstream screw 501. To achieve this configuration, in this embodiment, at the other end of the upstream screw 506, the blade 506b of the upstream screw 506 is in sliding contact with the inner wall surface of the upstream transport path 55 to support the upstream screw 506. Specifically, in a direction perpendicular to the rotation axis direction of the rotation shaft 506a, the entire outer periphery of the blade 506b farthest from the rotation shaft 506a or a portion thereof located vertically below the outer periphery slides and contacts the inner wall surface of the upstream transport path 55 to support the upstream screw 506. This allows a configuration in which the support portion of upstream screw 506 does not interfere with the toner transport, and further allows blade 506b of upstream screw 506 to apply a transport force to the toner up to just before it reaches downstream screw 501. As a result, the toner transport efficiency of toner transport device 50 can be further improved.

[0056] Therefore, the screw rotation speed can be kept to a minimum relative to the required amount of toner transport, which contributes to power savings and low noise.Similarly, the screw outer diameter can be minimized relative to the required amount of toner transport, which contributes to a smaller overall device size.

[0057] In this embodiment, the upstream screw and the downstream screw have the same parameters, but the present invention is not limited to this. Examples of parameters include the screw outer diameter, the central shaft outer diameter, the screw rotation speed, and the screw pitch, but the effect can be obtained regardless of the combination of screws with different parameters.

[0058] As in Example 1, instead of the upstream screw 506 having a rotating shaft 506a and a spiral blade 506b provided around the rotating shaft 506a, a screw having no rotating shaft but only blades made of a wire such as piano wire wound in a spiral may be used. In this way, various modifications are possible within the scope of the present invention. [Explanation of symbols]

[0059] 100 Image forming device 7 Photosensitive drum 3 Laser Scanner Unit 13 Refill toner container 14, 50 Toner transport device 15 Secondary transfer unit 22 Cleaning unit 26 Toner collection container 25 Fixing device 21 Paper output tray 51, 52, 54 Toner transport path 101, 55 Upstream transport path 102, 53 Downstream conveying path 103, 506 Upstream screw 104, 505 holes 105, 107, 502, 507 drive gear 106, 501 Downstream screw 203 Wall 504 Screw 508 Delivery Section

Claims

1. a first cylindrical member through which the toner is conveyed; a second cylindrical member into which the toner flowing from the first cylindrical member is conveyed upward; a first screw provided inside the first cylindrical member, the first screw having a first rotation shaft and transporting toner; a second screw provided inside the second cylindrical member, the second screw having a second rotation shaft and transporting toner; An image forming apparatus having: the first cylindrical member has a first end portion that is a downstream end portion of the first cylindrical member in a toner transport direction, the second cylindrical member has a second end portion that is an end portion on the upstream side in a toner transport direction of the second cylindrical member, The first screw further includes a first spiral blade provided around the first rotation shaft, the second screw further includes a second spiral blade provided around the second rotation shaft, the first cylindrical member and the second cylindrical member are connected such that their interiors communicate only at the first end and the second end, The rotation axis of the first rotation shaft of the first screw is arranged to intersect with an end of the second rotation shaft of the second screw. An image forming apparatus characterized by:

2. When the rotation axis is defined as a first rotation axis and the rotation axis of the second rotation shaft is defined as a second rotation axis, the first rotation axis intersects with the second rotation axis; Only the toner transported by the first screw is transported by the second screw.

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

3. a third cylindrical member connected to the second cylindrical member and through which toner is transported to the second cylindrical member; the toner transported by the first cylindrical member is joined with the toner transported by the second cylindrical member and then transported together with the toner transported by the third cylindrical member; 3. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

4. 2. The image forming apparatus according to claim 1, wherein the first screw is supported by an inner wall surface of the first cylindrical member with at least a portion of the first screw being in contact with the inner wall surface of the first cylindrical member.

5. 2. The image forming apparatus according to claim 1, wherein the second screw transports the toner vertically upward.

6. 2. The toner transport device according to claim 1, wherein the angle formed between a vector extending along the first cylindrical member from downstream to upstream in the direction in which toner is transported in the first screw and a vector extending along the second cylindrical member from upstream to downstream in the direction in which toner is transported in the second screw is 90 degrees or less.

7. an image forming unit that forms a toner image using toner; a toner container for supplying toner to the image forming unit; Further comprising:

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

8. an image forming unit that forms a toner image using toner; a cleaning unit that removes unused toner remaining in the image forming unit and cleans it; a toner recovery container that recovers and stores the toner removed by the cleaning unit; Further comprising:

4. The image forming apparatus according to claim 3, wherein the image forming apparatus is a recording medium.

Images