Powder conveying device and image forming apparatus

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 that transports 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 in which toner is stored, a powder transport means for transporting 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 the toner, a spiral screw having a rotation axis at its center is disposed in the transport path, and the toner is transported from the upstream to the downstream of the transport path by rotating the screw.

[0004] For example, a configuration is known in which toner is dropped and transported from a toner bottle arranged vertically above to a developing device through a toner transport path from a toner supply port to a developing device (Patent Document 1). In this configuration, two screws are crossed to transfer toner from upstream to downstream. The transfer section is arranged such that the downstream end of the upstream screw and the upstream end of the downstream screw cross each other so as to overlap in the vertical direction. 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] JP 2014-157350 A Summary of the Invention [Problem to be solved by the invention]

[0006] In this way, after the toner is transported by the transport force of the upstream screw, the toner is transferred from the upstream screw to the downstream screw by utilizing 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, and there is a problem in that the transport force cannot be increased sufficiently. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, the powder conveying device of the present application comprises a first conveying path, a second conveying path connected to the first conveying path, a first screw provided inside the first conveying path and rotated by a first driving means to convey powder, and a second screw provided inside the second conveying path and rotated by a second driving means to convey powder conveyed by the first screw, wherein 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 so that a virtual line extending in the direction of the rotation axis of the first screw intersects with the rotation shaft. Effect 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 description of the drawings]

[0009] [Figure 1] FIG. 2 is a diagram illustrating a toner conveying device according to the first embodiment. [Diagram 2] FIG. 2 is a diagram illustrating a toner conveying device according to the first embodiment. [Diagram 3] FIG. 1 is a diagram illustrating an image forming apparatus. [Figure 4] 13A and 13B are diagrams illustrating a toner transport device according to a modified example. [Diagram 5] FIG. 11 is a diagram illustrating a toner conveying device according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0011] In this embodiment, a four-drum electrophotographic 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 the outside and transfers and fixes the toner image as a color image on a recording material such as paper. Examples of the image forming apparatus include a copying machine, a laser beam printer, and a facsimile machine, but in this embodiment, a color laser beam printer will be described as an example.

[0012] The process cartridge is a cartridge that is detachably mountable to the main body of an image forming apparatus and that integrates at least a developing means and a photosensitive drum, which is a photosensitive member for electrophotography, as a process means. 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 side of the image forming apparatus, and the left side when facing the image forming apparatus will be referred to as the left side 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 separating means 23, and a pair of registration rollers 17 which sandwich and transport 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, a 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 mounting it in the image forming apparatus 100.

[0017] Above the paper feed device 10, there are disposed supply toner containers 13 (13a to 13d) for replenishing toner (powder) to the process cartridges 7 (7a to 7d) of the respective colors.

[0018] An exposure unit 3 is disposed above the supply toner container 13. The exposure unit 3 irradiates the photosensitive drum 1 with a laser based on image information to form an electrostatic latent image on the photosensitive drum 1.

[0019] Above the exposure unit 3, four photosensitive drums 1 (1a to 1d) are provided. Around each photosensitive drum 1, in the order of its rotation direction, 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) are provided. The photosensitive drum 1, the charging unit 2, the developing unit 4, and the cleaning unit 8 are each integrated into a cartridge to form a process cartridge 7 (7a to 7d). Each process cartridge 7 is provided detachably to the main body of the image forming apparatus 100, and in this embodiment, is configured to be detachably attached to 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 provided 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 are different in that they form images of different colors using yellow (Y), magenta (M), cyan (C), and black (Bk) toners.

[0021] The cleaning unit 5 (5a to 5d) includes 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 drum 1 (1a to 1d) is constructed by applying an organic photoconductor layer (OPC) to the outer circumferential surface of an aluminum cylinder, and both ends are rotatably supported by flanges. By transmitting a driving force from a driving motor to one end of the photosensitive drum 1 (1a to 1d), the photosensitive drum 1 (1a to 1d) is rotated in the clockwise direction shown by the arrow in FIG. 3.

[0023] The charging unit 2 (2a to 2d) is a conductive roller formed in a roller shape, 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 by applying a voltage thereto.

[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) which form toner images of each color, and the intermediate transfer unit 12 to 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 driving roller 12f, a driven roller 12g, primary transfer rollers 12 (12a to 12d), and a cleaning device 22 which is a cleaning section. The intermediate transfer belt 12e is an endless cylindrical belt that is stretched around the driving roller 12f and the driven roller 12g. The driven roller 12g is urged by a urging means and applies a predetermined tension to the intermediate transfer belt 12e. The intermediate transfer belt 12e rotates at a predetermined speed when the driving roller 12f is driven to rotate by a motor or the like. 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 roller 12 and the photosensitive drum 1 form a primary transfer section. Further, the driving roller 12f is disposed so as to face the secondary transfer member 16 via the intermediate transfer belt 12e, and the driving 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 configured to be stored in a toner recovery container 26 provided above the cleaning device 22.

[0028] In addition, 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 rotated 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 with the heating element 25a.

[0029] In addition, a pair of discharge rollers 20 and a discharge tray 21 are disposed downstream of the fixing device 25 in the conveying direction of the recording material S. The discharge tray 21 is a stacking section that stacks a plurality of sheets of recording material S and is formed on the top surface of the image forming apparatus 100, and has an inclined surface 21a that is inclined with respect to the horizontal direction. 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 section, is provided with the inclined surface 21a in order to maintain the alignment of the recording material S even if the succeeding recording material S is discharged in a state in which the recording material S is stacked on the discharge tray 21. As a result, the discharged recording material S is stacked on the discharge tray 21, which is a stacking section, while maintaining the alignment, without pushing out the stacked recording material S.

[0030] [Image formation process] First, the charging section 2 (2a to 2d) uniformly charges the surface of the photosensitive drum 1 (1a to 1d), and then the exposure section 3 irradiates each photosensitive drum 1 (1a to 1d) with a laser based on image information to form 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 developing unit 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 in succession on the intermediate transfer belt 12e by applying a voltage to the primary transfer roller 12 (12a to 12d), and are transported to the secondary transfer section 15. After the primary transfer, the toner (waste toner) remaining on the photosensitive drum 1 is removed by the cleaning section 8 and transported to a toner recovery container 26 arranged in 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 by one by a separating means 23. Thereafter, the recording material S is conveyed to the secondary transfer section 15 by a pair of registration rollers 17.

[0031] In 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 in the image forming apparatus 100. The recording material S conveyed from the secondary transfer section 15 is sandwiched and conveyed between a heating body 25a and a pressure roller 25b of a fixing device 25, and the toner image is heated and fixed onto the recording material S. The recording material S with the fixed toner image is then sandwiched and conveyed by a pair of discharge rollers 20, and discharged to a discharge tray 21.

[0032] [Toner transport device] 1 shows a detailed configuration of a toner transport device (powder transport device) 14 (14a to 14d) that transports toner from a 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 roughly divided into 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] Inside the upstream conveying path 101, an upstream screw (first screw) 103 having a rotating shaft 103a and a spiral blade 103b provided around the rotating shaft 103a is disposed. A hole 104 is disposed on the upper surface of the upstream conveying path 101. Toner in the supply toner container 13 is supplied from a supply port provided in the supply toner container 13 so as to fall onto the upstream screw 103 in the upstream conveying path 101 through the hole 104. 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 an end of the upstream screw 103 opposite the downstream conveying path 102 with respect to the hole 104, and the upstream screw 103 is driven to rotate by the drive gear 105. As a result, the upstream screw 103 is configured to convey the toner supplied to one end of the upstream screw 103 through the hole 104 to the downstream conveying path 102 disposed at the other end of the upstream screw 103 in the upstream conveying path 101.

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

[0035] At this time, the upstream screw 103 (rotating shaft 103a) is disposed so that a virtual line extending in the direction of the rotation axis intersects with the rotation axis of the downstream screw 106 (rotating 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, but is not limited to this and may be set to 90 degrees or less. In addition, in this embodiment, the upstream screw 103 and the downstream screw 106 have the same diameters d (mm) of the rotating shafts 103a and 106a. Therefore, the upstream screw 103 and the downstream screw 106 are disposed so that the outline of the rotating shaft 103a projected in the axial direction of the upstream screw 103 completely overlaps with the rotating 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 configured to continue to be conveyed by the blade 106b of the downstream screw 106 located at the destination of the conveyance. In other words, the conveying force obtained by the upstream screw 103 can be utilized when the toner is conveyed 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 the toner vertically upward against gravity in the downstream conveying path 102, the toner will flow back due to gravity unless the inside of the downstream conveying path 102 is filled with toner. However, in this embodiment, the conveying force of the upstream screw 103 is utilized to generate a sufficient inflow pressure that allows the toner to be conveyed by the downstream conveying path 102 against gravity.

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

[0038] In this embodiment, at the other end of the upstream screw 103 adjacent to the downstream conveying path 102, a blade 103b is provided around the rotating shaft 103a up to the other end of the upstream screw 103. This allows the conveying force applied to the toner by the upstream screw 103 to be transmitted to the downstream conveying path 102. To achieve this configuration, at the other end of the upstream screw 103, the blade 103b of the upstream screw 103 contacts the inner wall surface 203 of the upstream conveying path 101 so as to slide and support the upstream screw 103 (FIG. 2(b)). Specifically, in a direction perpendicular to the rotation axis direction of the rotating shaft 103a, the entire outer periphery of the blade 103b that is farthest from the rotating shaft 103a or a part located vertically below the rotating shaft 103a slides and contacts the inner wall surface 203 of the upstream conveying 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 until it reaches 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, there are two ways to increase the amount of toner transported: increasing the outer diameter of the screw to increase the volume of the transport path, and increasing the number of rotations of the screw. Both of these methods increase the volume of the screw moving per unit time to increase the amount of toner transported. However, the method of increasing the number of rotations of the screw increases power consumption and operating noise, and the method of increasing the outer diameter of the screw to increase the volume of the transport path increases the size of the device. However, with the configuration of this embodiment, the toner transported can be efficiently transferred to the downstream screw by using the transport force of the upstream screw at the transfer section. Therefore, the number of rotations of the screw can be minimized for the required amount of toner transported, thereby realizing power saving and low noise. Similarly, the outer diameter of the screw can be minimized for the required amount of toner transported, thereby realizing a small size of the entire device.

[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 has been described as being 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 portion 8 of the cleaning unit 5 to be stored in the toner recovery container 26.

[0042] In addition, in the first embodiment, the upstream screw 103 having the rotating shaft 103a and the spiral blade 103b provided around the rotating shaft 103a is used, but the present invention is not limited to this. For example, as shown in FIG. 4, a screw having only a blade wound in a spiral shape of a wire such as a piano wire without a rotating shaft may be used as the upstream screw 103. In this case, it is sufficient that the upstream screw 103 is arranged so that a virtual 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 (rotating shaft 106a) are arranged so as to intersect. Even in this case, the toner conveying efficiency of the toner conveying device 14 can be improved, and the same effect as in the first embodiment can be obtained. EXAMPLES

[0043] A second embodiment of the present invention will be described below. In the first embodiment, the toner conveyed by the upstream conveying path 101 is supplied to an end portion located below the downstream conveying path 102 extending in the vertical direction, and is conveyed by the downstream screw 106. However, the present invention may be applied to a toner conveying device 50 that collects toner (waste toner) remaining on the intermediate transfer belt 12e without being transferred at the secondary transfer unit 15 by the cleaning device 22 and conveys the toner from the toner conveying path 55 to the toner conveying path 53, as shown in FIG. 5.

[0044] In the toner transport device 50, the toner (waste toner) remaining on the photosensitive drum 1 that is not transferred in the primary transfer unit is collected by the cleaning unit 8, transported in the order of toner transport paths 51 (51a to 51d), 52, 53, and 54, and stored in the toner recovery container 26. Therefore, the toner collected in the primary transfer unit and the secondary transfer unit join together at a transfer unit 508 from the upstream transport path 55 to the downstream transport path 53, and is transported from the toner transport path 53 to the toner recovery container 26 via the 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 a screw disposed inside the toner transport device shown in Fig. 5(a) and its driving configuration.

[0046] The toner remaining on the intermediate transfer belt 12e that is not transferred at the secondary transfer unit 15 is collected by the cleaning device 22, and then the collected toner is transported from the front side to the rear side of the image forming apparatus 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 conveying path 55. The toner collected in the cleaning device 22 is supplied to the upstream screw 506 in the upstream conveying path 55 through the hole 505 so as to fall onto the upstream screw 506. The upstream screw 506 is provided with a drive gear 507, to which a rotational force is input from a drive source (first drive means) such as a motor (not shown), at an end opposite the downstream conveying path 53 with respect to the hole 505, and the upstream screw 506 is driven to rotate by the drive gear 507. Thus, the upstream screw 506 is configured to convey the toner supplied to one end of the upstream screw 506 through the hole 505 to the downstream conveying path 53 disposed at the other end of the upstream screw 506 in the upstream conveying path 55.

[0048] A downstream screw 501 having a rotating shaft 501a and a spiral blade 501b provided around the rotating shaft 501a is disposed inside the downstream transport path 53. The downstream transport path 53 extends in the vertical direction 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. The downstream screw 501 is provided at one end vertically below with a drive gear 502 to which a rotational force is input from a drive source (second drive means) such as a motor (not shown), and the downstream screw 501 is configured to be rotatable by the drive gear 502.

[0049] Meanwhile, the toner remaining on the photosensitive drum 1 (1a to 1d) that has not been 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 in the downstream transport path 53 between a 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 has not been 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 the drive gear 502 is driven, the downstream screw 501 transports the waste toner of the primary transfer unit delivered by the toner transport path 52 and the waste toner of the primary transfer unit delivered from the upstream screw 506 of the upstream transport path 55. The toner transported by the downstream screw 501 is transported to the toner recovery container 26 via the toner transport path 54 at the downstream end (vertically upward) of the downstream screw 501. The toner transport path 54 has a screw 504 therein, the screw 504 having a rotation shaft and a spiral blade provided around the rotation shaft. The screw 504 is driven to rotate by a drive gear 503 connected to the screw 504, and is provided so as to be able to transport the waste toner of the primary transfer unit and the secondary transfer unit to the toner recovery container 26.

[0051] In this embodiment, the upstream screw 506 (rotation shaft 506a) is disposed so that a virtual line extending in the direction of the 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, but is not limited to this and may be set to 90 degrees or less. In addition, in this embodiment, the upstream screw 506 and the downstream screw 501 have the same diameter d (mm) of the rotation shafts 506a and 501a. Therefore, the upstream screw 506 and the downstream screw 501 are disposed so that the outline of the rotation shaft 506a projected in the direction of the rotation axis of the upstream screw 506 completely overlaps with the rotation shaft 501a of the downstream screw 501.

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

[0053] Furthermore, when the downstream screw 501 transports the toner vertically upward against gravity, the toner will flow back due to gravity unless the inside of the downstream transport path 53 is filled with toner. On the other hand, in a configuration in which the 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 and 501a, but this is not limited to the above. When the diameters of the rotation shafts 506a and 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 conveying efficiency of the toner conveying device 50 can be improved.

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

[0056] Therefore, the number of rotations of the screw can be kept to a minimum for the required amount of toner transport, which can save power and reduce noise.Similarly, the outer diameter of the screw can be minimized for the required amount of toner transport, which can reduce the size of the entire device.

[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 the first embodiment, instead of the upstream screw 506 having the rotating shaft 506a and the spiral blade 506b provided around the rotating shaft 506a, a screw having no rotating shaft and only blades made of a wire such as a 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 section 22 Cleaning unit 26 Toner collection container 25 Fixing device 21 Paper output tray 51, 52, 54 Toner transport path 101, 55 Upstream conveying 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 toner is transported; a second cylindrical member through which the 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 shaft and configured to transport toner; a second screw provided inside the second cylindrical member, the second screw having a second rotation shaft and configured to transport toner; An image forming apparatus having the first cylindrical member has a first end portion which is a downstream end portion of the first cylindrical member in a toner transport direction, the second cylindrical member has a second end portion which is an upstream end portion of the second cylindrical member in a toner transport direction, 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.

1. An image forming apparatus comprising:

2. The first screw further has a spiral first blade provided around the first rotating shaft, The second screw further includes a second helical blade provided around the second rotation shaft, When the rotation axis of the second rotation shaft 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.

2. The image forming apparatus according to claim 1,

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 first and second electrodes are arranged in a first direction.

4. 2 . The image forming apparatus according to claim 1 , wherein the first screw is supported by at least a portion of the first cylindrical member in contact with an 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 an angle between a vector extending along the first cylindrical member from the downstream side to the upstream side in the direction in which toner is transported in the first screw and a vector extending along the second cylindrical member from the upstream side to the downstream side in the direction in which toner is transported in the second screw is less than 90 degrees.

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,

8. An image forming unit that forms a toner image using toner; a cleaning unit that removes and cleans toner remaining in the image forming unit; 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.

Images