Toner conveying device

Abstract

To improve toner conveyance efficiency on a downstream side of a toner conveyance path.SOLUTION: A toner conveying device comprises: a conveyance path that has piping, a rotatable screw provided in the piping, and an opening provided in the piping, the conveyance path having the opening arranged on a downstream side of the conveyance path; and a driving unit that rotates the screw. The screw extends to near the opening, and for the cross section of a space formed between an inner wall of the piping and the screw in a direction orthogonal to the direction of the axis of rotation of the screw, the cross section of the space near the opening is smaller than the cross section of the space other than near the opening.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a toner transport device that transports toner, and an electrophotographic image forming apparatus having the toner transport device. [Background technology]

[0002] Conventionally, image forming devices using electrophotography, such as printers, copiers, and facsimiles, are composed of three parts: a toner storage section that initially stores toner, a powder transport means that transports the toner, and an image forming section located downstream of the toner storage section. As a toner transport configuration, a helical screw with a rotation axis at the center is placed in the transport path and rotated to transport the toner from the upstream to the downstream of the transport path. Patent Document 1 shows a configuration in which toner is dropped and transported from a toner bottle arranged vertically above a toner storage unit through a toner transport path to a developing device from a toner supply port. In the configuration shown in Figures 9 and 11 of Patent Document 1, the toner is transported to a desired toner supply port by changing the transport direction and height of the toner using a plurality of screws arranged in a toner transport path that interconnects a plurality of transport paths. For example, in the configuration shown in FIG. 10 of Patent Document 1, two screws are arranged to cross each other in the vertical direction, and toner is transferred from upstream to downstream. In the toner transfer section, the downstream end of the upstream screw and the upstream end of the downstream screw are arranged to cross each other and overlap in the vertical direction. When the toner transported by the upstream screw reaches the downstream end of the upstream screw, it is guided to the downstream screw with the help of gravity. The toner is transported further downstream by the downstream screw. Similarly, Patent Document 2 also discloses a configuration in which two screws are arranged to intersect in the vertical direction, and toner is transported by transferring it from the upstream screw to the downstream screw. As shown in Fig. 8 of Patent Document 2, the upstream screw and the downstream screw intersect in the vertical direction, and the toner is transported downstream in the transport direction. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-157350 A [Patent Document 2] JP 2012-230358 A Summary of the Invention [Problem to be solved by the invention]

[0004] In these conventional techniques, at the transfer section from the upstream screw to the downstream screw, the toner is subjected to gravity in addition to the conveying force of the screw. The sum of the conveying force of the screw and gravity pushes the toner out of the conveying path where the upstream screw is located, and the toner flows into the conveying path where the downstream screw is located (the downstream side of the toner conveying path). There is a demand for improving the toner conveying efficiency on the downstream side of the toner conveying path.

[0005] The present invention has been made in view of the above-mentioned problems, and has an object to provide a technique capable of improving the toner transport efficiency on the downstream side of the toner transport path. [Means for solving the problem]

[0006] In order to achieve the above object, the toner conveying device of the present invention comprises: a first transport unit including: a first tube; a first screw provided within the first tube and rotatable about a rotation axis; an opening provided on a side surface of the first tube extending in the direction of the rotation axis, the opening being disposed downstream of the first tube in a toner transport direction by the first screw; and an end surface of the first tube that is disposed downstream of the opening in the toner transport direction and intersects with the rotation axis; a second transport unit including: a second tube connected to the first tube such that an interior of the second tube communicates with the opening of the first tube and extending upward; and a second screw provided within the second tube for transporting the toner received through the opening of the first tube upward; A drive unit for supplying a drive force for rotating the first screw and the second screw; A toner conveying device comprising: The first screw overlaps with the opening when viewed in a direction perpendicular to the rotation axis. It extends like a ridge. In the toner transport direction, a downstream end of the first screw is located upstream of the end surface of the first tube. the law of nature , The first screw has a rotating shaft portion centered on the rotation axis and a helical portion provided on the outer periphery of the rotating shaft portion in a radial direction of the rotating shaft portion centered on the rotation axis, and is configured such that the downstream tip does not have a portion protruding outward from an outermost diameter portion of the helical portion in the radial direction. Characterized by 。 Effect of the Invention

[0007] According to the present invention, it is possible to improve the toner transport efficiency on the downstream side of the toner transport path. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is an explanatory diagram of a toner conveying device according to a first embodiment of the present invention; [Diagram 2] FIG. 1 is a perspective view of a toner conveying device according to a first embodiment of the present invention; [Diagram 3] Schematic cross-sectional view of an image forming apparatus according to a first embodiment of the present invention. [Figure 4] FIG. 11 is an explanatory diagram of a toner conveying device according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] 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.

[0010] Example 1 Image forming apparatus 1 according to a first embodiment of the present invention will be described with reference to Fig. 3. Fig. 3 is a schematic cross-sectional view showing the overall configuration of image forming apparatus 1, and is a cross-sectional view of image forming apparatus 1 as viewed from the front side. Fig. 3 shows the configuration of the image forming apparatus in a normal installation state in which the image forming apparatus is placed on a horizontal installation surface, with the left-right direction on the page corresponding to the horizontal direction and the up-down direction on the page corresponding to the up-down direction of the apparatus.

[0011] The image forming apparatus 1 includes an image forming section 6 as an image forming means, which is made up of image forming stations 6Y, 6M, 6C, and 6K arranged in a horizontal row, corresponding to toners (developers) of the respective colors of yellow (Y), magenta (M), cyan (C), and black (K). The image forming section 6 includes photoconductor drums 7Y, 7M, 7C, and 7K (hereinafter referred to as photoconductor drums 7) which are image carriers, and charging devices 8Y, 8M, 8C, and 8K (charging devices 8) which uniformly charge the surfaces of the photoconductor drums 7. The image forming section 6 also includes developing devices 9Y, 9M, 9C, and 9K (developing devices 9) which attach toner to the electrostatic latent images formed on the photoconductor drums 7 and develop them into toner images (developer images). Furthermore, the image forming section 6 is provided with photoconductor cleaning blades 10Y, 10M, 10C, 10K (photoconductor cleaning blades 10) for removing residual toner remaining on the photoconductor drum 7. The developing device 9 is provided with developing rollers 11Y, 11M, 11C, 11K (developing rollers 11) for each color, which are configured to be able to come into contact with and separate from the photoconductor drums 7. The developing rollers 11 come into contact with and separate from the photoconductor drums 7 in accordance with the electrostatic latent image, i.e., depending on whether development is required or not, thereby improving the life of the developing rollers 11. A scanner unit 12, which irradiates a laser beam based on image information to form an electrostatic latent image on the photoconductor drum 7, is located below the image forming section 6. The image forming stations 6Y, 6M, 6C, and 6K are configured as process cartridges that can be detachably attached to the main body of the image forming apparatus 1. The process cartridge is configured so that the developing device 9 equipped with the developing roller 11 and the photoconductor unit equipped with the photoconductor drum 7, the charging device 8, and the photoconductor cleaning blade 10 can be detachably attached to the main body of the image forming apparatus 1, either individually or as a whole. In this embodiment, the developing device 9 has its own toner storage chamber, and the toner stored in the toner storage chamber is replenished with toner supplied from a refill toner container (toner cartridge) 13. Here, the main body of the image forming apparatus 1 refers to the components excluding components that can be detachably attached to the image forming apparatus 1, such as the above-mentioned process cartridge and refill toner container 13.

[0012] Meanwhile, a cassette 2 is housed in the lower part of the image forming apparatus 1 so as to be removable. Recording materials 4 such as paper or sheets are housed in the cassette 2. The recording materials 4 are separated and fed one by one by the rotation of a cassette feed section 3 arranged near the leading end of the recording materials 4. Thereafter, the recording materials 4 are transported downstream by registration rollers 5.

[0013] An intermediate transfer unit 16 is provided above the developing device 9. The intermediate transfer unit 16 is disposed substantially horizontally with the side facing each image forming station (image forming section) 6 (primary transfer section 20 side) facing downward. The intermediate transfer belt 18 facing each photosensitive drum 7 is a rotatable endless belt, and is stretched around a plurality of tension rollers. Primary transfer rollers 19Y, 19M, 19C, and 19K (primary transfer rollers 19) are disposed on the inner side of the intermediate transfer belt 18 as primary transfer members. Each primary transfer roller 19 is disposed at a position that forms a primary transfer section 20Y, 20M, 20C, and 20K (primary transfer section 20) with each photosensitive drum 7 via the intermediate transfer belt 18. In each primary transfer section 20, a toner image is transferred from each photosensitive drum 7 to the intermediate transfer belt 18 by the primary transfer roller 19 to which a voltage is applied. In this embodiment, a unit including the intermediate transfer belt 18, a plurality of tension rollers around which the intermediate transfer belt 18 is tensioned, and each of the primary transfer rollers 19 is configured as an intermediate transfer unit 16 that is detachably attached to the main body of the apparatus. The toner images developed at each image forming station are transferred to the intermediate transfer belt 18 at the primary transfer unit 20, and by successively transferring each color, a toner image consisting of four colors is formed on the surface of the intermediate transfer belt 18, and then the toner image is transported to the secondary transfer unit 17.

[0014] Below the image forming section 6, between the scanner unit 12 and the cassette 2, refill toner containers 13Y, 13M, 13C, and 13K (refill toner containers 13) for refilling toner to each image forming station (image forming section) 6 are disposed substantially horizontally and detachably. The refill toner containers 13 are also called toner refill cartridges. Refill toner corresponding to each color is filled inside the refill toner containers 13. The toner conveying devices 14Y, 14M, 14C, and 14K (toner conveying devices 14) convey the toner received from the refill toner containers 13 upward in accordance with the toner consumption in the image forming section 6, and supply the toner to the developing device 9. The toner conveying device 14 is driven by toner conveying drive devices 15Y, 15M, 15C, and 15K (toner conveying drive devices 15) as drive means disposed below the toner conveying device 14.

[0015] A secondary transfer roller 21, which is a secondary transfer member, contacts the intermediate transfer belt 18 and forms a secondary transfer section 17 with an opposing roller via the intermediate transfer belt 18. In the secondary transfer section 17, the toner image transferred onto the intermediate transfer belt 18 is secondarily transferred onto the recording material 4. The recording material 4 onto which the unfixed toner image has been transferred is transported further downstream and pressurized and heated by a fixing device 25, which melts the toner and fixes the toner image to the recording material 4. The recording material 4 is then discharged onto a paper discharge tray 27. Through this series of operations, an image is formed on the surface of the recording material 4.

[0016] The image forming apparatus 1 is provided with a toner recovery container (container) 24 for recovering so-called waste toner discharged in the primary transfer and secondary transfer. In the primary transfer and secondary transfer, electrophotographic transfer is performed using electrostatic force. Therefore, not all of the original toner image is transferred, and a few percent of the toner image remains on the surface of the original photoconductor drum 7 and on the surface of the intermediate transfer belt 18. The remaining toner that has not been transferred is cleaned to improve the stability of image formation. The cleaned remaining toner becomes waste toner and is collected in the toner recovery container 24.

[0017] The waste toner transport device (toner transport device) which is a toner transport section includes waste toner transport paths 51Y, 51M, 51C, and 51K (waste toner transport path 51) and waste toner transport paths 52, 53, and 54. The waste toner transport device also includes a drive device (drive section) which rotates a screw which transports the waste toner in the waste toner transport paths 51, 52, 53, and 54.

[0018] The transport operation of the waste toner (residual toner) from the primary transfer unit 20 and the secondary transfer unit 17 to the toner recovery container 24 will be described below. The toner remaining after the primary transfer (the remaining toner on the surface of the photoconductor drum 7) is collected by the photoconductor cleaning blade 10, transported through the waste toner transport paths 51, 52, 53, and 54 in this order, and stored in the toner recovery container 24. The toner remaining in the secondary transfer section 17 (the remaining toner on the surface of the intermediate transfer belt 18) is collected by the cleaning unit 22. The remaining toner collected by the cleaning unit 22 is then transported from the waste toner transport path 55 to the waste toner transport path 53, and is collected as waste toner in the toner recovery container 24 together with the remaining toner collected by the photoconductor cleaning blade 10. The waste toner transport device is mounted on the image forming apparatus 1 and used in the image forming apparatus 1. The waste toner transport paths 51, 52, 53, and 54 may be detachable from the image forming apparatus 1.

[0019] Fig. 2(a) shows a detailed configuration of waste toner transport paths 52 and 53 mounted on image forming apparatus 1, and Fig. 2(b) shows a detailed internal configuration. Waste toner of each color flows into waste toner transport path 52 from waste toner transport path 51. Waste toner transport path 52 has a rotatable screw 202 (first screw) that transports waste toner (powder). The waste toner that flows into waste toner transport path 52 is transported to the downstream side of waste toner transport path 51 by the rotation of screw 202. Screw 202 is rotationally driven by a rotational driving force transmitted from a driving device (first driving unit) to driving gear 201.

[0020] The waste toner transport path 53 is connected to the waste toner transport path 52. The waste toner transport path 53 has a rotatable downstream screw 204 (second screw) that transports the waste toner. The waste toner transported downstream of the waste toner transport path 52 flows into the waste toner transport path 53. The waste toner that has flowed into the waste toner transport path 53 is transported vertically upward (vertically upward) by the rotation of the downstream screw 204. The downstream screw 204 is rotationally driven by a rotational driving force transmitted to the drive gear 203 from a drive device (second drive unit).

[0021] Next, the characteristic screw configuration and its effect according to this embodiment will be described. FIG. 1 is an explanatory diagram of a toner conveying device, showing the internal configuration on the downstream side of the waste toner conveying path 52 of the toner conveying device. The screw 202, which is a conveying member, has a rotating shaft and is rotatable. The screw 202 has a large diameter screw portion 202a, a small diameter screw portion 202b, a rotating shaft portion 202c (large diameter shaft portion), and a rotating shaft portion 202d (small diameter shaft portion). The large diameter screw portion 202a is provided by being wound in a spiral shape around the outer periphery of the rotating shaft portion 202c, and the small diameter screw portion 202b is provided by being wound in a spiral shape around the outer periphery of the rotating shaft portion 202d. The large diameter screw portion 202a and the small diameter screw portion 202b are vane portions having a vane shape.

[0022] The screw 202 has a first screw portion formed by a large diameter screw portion 202a and a rotating shaft portion 202c, and a second screw portion formed by a small diameter screw portion 202b and a rotating shaft portion 202d. The first screw portion of the screw 202 is disposed on the upstream side of the waste toner transport path 52. The second screw portion of the screw 202 is disposed on the downstream side of the waste toner transport path 52. The first screw portion of the screw 202 (the large diameter screw portion 202a and the rotating shaft portion 202c) is disposed on the upstream side of the waste toner transport direction (the upstream side of the waste toner transport path 52) of the point where the cross-sectional area of ​​the waste toner transport path 52 changes (cross-sectional area change point). The waste toner transport direction in the waste toner transport path 52 is the rotation axis direction of the screw 202, and is the direction toward the connecting portion between the waste toner transport path 52 and the waste toner transport path 53. The waste toner transport path 52 is disposed in the image forming apparatus 1 so that the rotation axis direction of the screw 202 coincides with the horizontal direction.

[0023] The outer diameter (screw outer diameter) of the large diameter screw portion 202a is φDa1. Therefore, the outer diameter (diameter) of the first screw portion formed by the large diameter screw portion 202a and the rotating shaft portion 202c is φDa1. 1 / 2 of the outer diameter (φDa1) of the large diameter screw portion 202a is the distance from the rotation center line (rotation axis) of the rotating shaft portion 202c to the outer circumferential end of the large diameter screw portion 202a. The second screw portion (small diameter screw portion 202b and rotating shaft portion 202d) of the screw 202 is disposed downstream in the waste toner transport direction (downstream of the waste toner transport path 52) with the cross-sectional area change point as the boundary. The outer diameter of the small diameter screw portion 202b is φDa2. Therefore, the outer diameter of the second screw portion formed by the small diameter screw portion 202b and the rotating shaft portion 202d is φDa2. The distance from the rotation center line of the rotating shaft portion 202d to the outer circumferential end of the small diameter screw portion 202b is half the outer diameter (φDa2) of the small diameter screw portion 202b. The large diameter screw portion 202a and the small diameter screw portion 202b are formed so that the outer diameter (φDa2) of the small diameter screw portion 202b is smaller than the outer diameter (φDa1) of the large diameter screw portion 202a (φDa1>φDa2).

[0024] Additionally, the outer diameter of the rotating shaft portion 202c of the large diameter screw portion 202a is φd1. The outer diameter of the rotating shaft portion 202d of the small diameter screw portion 202b is φd2. The rotating shaft portion 202c and the rotating shaft portion 202d are formed such that the outer diameter (φd2) of the rotating shaft portion 202d of the small diameter screw portion 202b is smaller than the outer diameter (φd1) of the rotating shaft portion 202c of the large diameter screw portion 202a (φd1>φd2).

[0025] Around the screw 202, a pipe section 101 (first piping) having an inner diameter of φDb1 and a pipe section 102 (second piping) having an inner diameter of φDb2 are provided according to the outer diameter of the screw 202. The pipe section 101 is disposed on the upstream side of the waste toner transport path 52. The pipe section 102 is disposed on the downstream side of the waste toner transport path 52. The pipe section 101 and the pipe section 102 are formed such that the inner diameter (φDb2) of the pipe section 102 is smaller than the inner diameter (φDb1) of the pipe section 101. The pipe section 101 and the pipe section 102 form a pipe 104 into which the waste toner flows. The pipe 104 is provided in the waste toner transport path 52. The screw 202 is provided inside the pipe (inside the pipe 104). An outlet (opening) 103 is provided at the end of the pipe 102 , and the outlet 103 is disposed downstream of the waste toner transport path 52 .

[0026] The screw 202 extends to the vicinity of the hole 103 of the pipe section 102. That is, a second screw portion of the screw 202 is disposed near the hole 103 of the pipe section 102. In FIG. 1, the vicinity of the hole 103 of the pipe section 102 includes a region overlapping with the hole 103 and a peripheral region of the region overlapping with the hole 103 when viewed from a direction perpendicular to the rotational axis direction of the screw 202. In FIG. 1, the hole 103 is provided in the pipe section 102 so as to face the direction perpendicular to the rotational axis direction of the screw 202. When viewed from the opposite direction, the screw 202 extends to the vicinity of the hole 103 so that a part of the screw 202 (second screw portion) and a part of the hole 103 overlap. Not limited to the configuration of FIG. 1, when viewed from a direction perpendicular to the rotation axis direction of the screw 202, the screw 202 and the hole 103 may not overlap. Also, the hole 103 may be provided in the pipe part 102 so as to face the rotation axis direction of the screw 202. In this case, when viewed from the rotation axis direction of the screw 202, the screw 202 extends to the vicinity of the hole 103 so that a part of the screw 202 (second screw portion) and a part of the hole 103 overlap. Not limited to this configuration, when viewed from the rotation axis direction of the screw 202, the screw 202 and the hole 103 may not overlap.

[0027] The waste toner transported to the waste toner transport path 52 is pushed out toward the waste toner transport path 53 through the hole 103 of the pipe portion 102. That is, as the screw 202 rotates, the waste toner in the pipe portion 101 flows into the pipe portion 102, and the waste toner is discharged from the hole 103 of the pipe portion 102. Therefore, the hole 103 is an outlet for discharging the waste toner in the pipe portion 102. When the waste toner is transported into the waste toner transport path 52, the waste toner is distributed in the area A1 indicated by the diagonal hatching in FIG. 1 within the waste toner transport path 52, and the area (neighboring area) near the hole 103 in the waste toner transport path 52 becomes filled with the waste toner.

[0028] In a conventional configuration, even if a space is formed above the horizontally arranged screw when viewed from an axial cross section, as in the arrangement shown in Fig. 9 of Patent Document 1, the toner does not enter the space and is transported in the axial direction of the screw. In such a case, the transport force acting on the toner when transferring it from the upstream screw to the downstream screw is the sum of the radial transport force generated by the screw and gravity. Therefore, when (1) the downstream screw is positioned vertically above the upstream screw, or (2) the transport path is inclined so that the end of the downstream screw becomes higher as it approaches the downstream side of the transport path, the radial transport force of the screw alone may be insufficient and the toner may not be transported smoothly. In the above configurations (1) and (2), the transfer section between the upstream and downstream screws becomes a bottleneck, reducing the conveying efficiency, and therefore the maximum conveying force of the entire system is reduced relative to the maximum conveying force of each screw. For this reason, in conventional image forming apparatuses, the amount of toner required by the process cartridge is set, and in order to meet the set amount of toner, the rotation speed of the screw is increased to meet the amount of toner transport. However, while the required amount of toner transport is achieved, the increased rotational speed of the screw increases the operating noise, and the cumulative number of rotations of the screw in the powder transport device increases over the product life of the image forming apparatus, shortening the life of the device. Furthermore, increasing the screw rotation speed increases the damage to the toner caused by pressure and friction during transport, causing the toner to melt and, in the worst case, preventing the screw from rotating and clogging the transport path.

[0029] On the other hand, in this embodiment, waste toner transport path 53 (second transport path) is connected to hole 103 of pipe portion 102. That is, waste toner flows into waste toner transport path 53 through hole 103. Hole 103 can also be considered a communication port that communicates waste toner transport path 52 and waste toner transport path 53. As a result, when waste toner that has flowed into waste toner transport path 53 is transported vertically upward, the area in waste toner transport path 52 near hole 103 is filled with waste toner. In this state, the graph shown in FIG. 1 shows the effective cross-sectional area of ​​the transport path and the pressure applied to the waste toner, with the horizontal axis representing the position in the waste toner transport direction.

[0030] Here, the effective cross-sectional area of ​​the conveying path will be described. The effective cross-sectional area of ​​the pipe portion 101 is the cross-sectional area of ​​the rotating shaft portion 202c of the screw 202 in the orthogonal direction from the cross-sectional area of ​​the pipe portion 101 in the direction perpendicular to the rotation axis direction of the screw 202 (hereinafter referred to as the orthogonal direction). In other words, the effective cross-sectional area of ​​the pipe portion 101 is the cross-sectional area of ​​the space formed between the inner wall 101a of the pipe portion 101 and the rotating shaft portion 202c of the screw 202 in the orthogonal direction. The effective cross-sectional area of ​​the pipe portion 102 is the cross-sectional area of ​​the pipe portion 102 in the orthogonal direction minus the cross-sectional area of ​​the rotating shaft portion 202d of the screw 202 in the orthogonal direction. In other words, the effective cross-sectional area of ​​the pipe portion 102 is the cross-sectional area of ​​the space formed between the inner wall 102a of the pipe portion 102 and the rotating shaft portion 202d of the screw 202 in the orthogonal direction. The effective cross-sectional area of ​​the waste toner transport path 52 is the effective cross-sectional area of ​​the pipe portion 101 or the effective cross-sectional area of ​​the pipe portion 102. The effective cross-sectional area of ​​the waste toner transport path 52 is equal to the cross-sectional area of ​​the region of the waste toner transport path 52 through which the waste toner passes.

[0031] In the first embodiment, the outer diameter of the screw 202 is changed to make the effective cross-sectional area of ​​the waste toner transport path 52 downstream of the cross-sectional area change point (downstream effective cross-sectional area) different from the effective cross-sectional area of ​​the waste toner transport path 52 upstream of the cross-sectional area change point (upstream effective cross-sectional area). That is, the effective cross-sectional area of ​​the waste toner transport path 52 is set so that the downstream effective cross-sectional area is smaller than the upstream effective cross-sectional area. For example, the effective cross-sectional area of ​​the waste toner transport path 52 near the hole 103 (effective cross-sectional area of ​​the pipe portion 102) is smaller than the effective cross-sectional area of ​​the waste toner transport path 52 other than the vicinity of the hole 103 (effective cross-sectional area of ​​the pipe portion 101).

[0032] The pressure applied to the waste toner gradually increases from the retention start point toward the downstream side. The amount of waste toner per cross-sectional area of ​​the waste toner transport path 52 starts to increase from the retention start point. The effective cross-sectional area of ​​the waste toner transport path 52 decreases from the cross-sectional area change point toward the downstream side of the waste toner transport path 52. Therefore, the gradient of the increase in the pressure applied to the waste toner starts to increase from the cross-sectional area change point, and finally the pressure applied to the waste toner at the discharge port (hole 103) of the waste toner transport path 52 becomes maximum. By the pressure applied to the waste toner at the discharge port of the waste toner transport path 52 becoming maximum, the pressure necessary for the waste toner transport path 53 to transport the waste toner in the vertically upward direction is ensured. This allows the waste toner to flow from the waste toner transport path 52 to the waste toner transport path 53 every time waste toner is supplied to the waste toner transport path 52.

[0033] In a conventional transport configuration that does not have a cross-sectional area change point, the gradient of the increase in pressure applied to the waste toner from the retention start point to the discharge outlet of the transport path is gentle. Therefore, the retention start point in the conventional configuration is located upstream of the waste toner transport path 52 compared to the configuration of this embodiment. By reducing the effective cross-sectional area of ​​the waste toner transport path 52 downstream of the waste toner transport path 52 as in the configuration of this embodiment, the amount of waste toner retained between the retention start point and the discharge outlet of the waste toner transport path 52 can be relatively reduced.

[0034] When the waste toner is pressurized, it may melt or stick together, which may cause clogging of the toner in the transport path. According to the configuration of this embodiment, the amount of waste toner remaining in the waste toner transport path 52 is reduced, thereby reducing the risk of clogging of the waste toner in the waste toner transport path 52. In addition, by reducing the effective cross-sectional area of ​​the waste toner transport path 52 on the downstream side of the waste toner transport path 52, the flow speed of the waste toner from the retention start point to the discharge outlet of the waste toner transport path 52 is increased. Therefore, the time required for the waste toner to move in the waste toner transport path 52 is shortened, and the time during which pressure is applied to the waste toner in the waste toner transport path 52 can also be shortened. As a result, melting of the waste toner and sticking of the waste toner together can be suppressed.

[0035] In this embodiment, the length from the cross-sectional area change point to the discharge outlet (hole 103) of the waste toner transport path 52 is the same as the pitch of one rotation of the spiral shape of the small diameter screw portion 202b. The effective cross-sectional area of ​​small diameter screw portion 202b (effective cross-sectional area of ​​pipe portion 101) is smaller than the effective cross-sectional area from the cross-sectional area change point to the upstream end of waste toner transport path 52. In the region from the cross-sectional area change point to the discharge port (hole 103) of waste toner transport path 52, small diameter screw portion 202b makes at least one revolution around rotating shaft portion 202d. This prevents the waste toner from flowing in the opposite direction to the waste toner transport direction in waste toner transport path 52, and allows the waste toner to be efficiently transported to the downstream side of waste toner transport path 52. Therefore, the waste toner can be efficiently discharged from the discharge port (hole 103) of waste toner transport path 52.

[0036] According to this embodiment, when the waste toner is transported vertically upward, the necessary inflow pressure to the waste toner transport path 53 can be efficiently generated. Therefore, the toner transport efficiency on the downstream side of the toner transport path can be improved. Also, the toner transport efficiency in the toner transport path where the downstream side is more affected by gravity than the upstream side can be improved. Therefore, it is possible to suppress an increase in operating noise and a shortened device life that occur when the rotation speed of the screw is increased. Also, by moving the retention start point closer to the discharge port (hole 103) of the waste toner transport path 52, the area where pressure is applied to the waste toner is reduced, and the time that the waste toner passes through the waste toner transport path 52 is reduced. This reduces damage to the waste toner.

[0037] In addition, in this embodiment, a configuration is adopted in which waste toner transport path 53 is arranged along the vertical direction, that is, a configuration in which the longitudinal direction of waste toner transport path 53 (the direction of the rotation axis of downstream screw 204) coincides with the vertical direction, but this configuration is not limited to this. A configuration in which the longitudinal direction of waste toner transport path 53 is different from the vertical direction may also be adopted. The same effect can be obtained regardless of the angle at which the longitudinal direction of waste toner transport path 53 is inclined relative to the vertical direction. Furthermore, the same effect can be obtained regardless of the angle of the longitudinal direction of waste toner transport path 52 (the direction of the rotation axis of screw 202) relative to the longitudinal direction of waste toner transport path 53.

[0038] The same effect can be obtained not only in the case of waste toner but also in the case of a configuration for transporting powder such as toner before development. For example, the toner transport device 14 may be provided with a toner transport path having a similar configuration to the waste toner transport path 52 and a toner transport path having a similar configuration to the waste toner transport path 53. In this embodiment, parameters such as the outer diameter of the screw 202 are set one each before and after the cross-sectional area change point. Since the effect can be obtained by changing the outer diameter of the screw 202 in at least one step, the parameters such as the outer diameter of the screw 202 may be changed steplessly.

[0039] Example 2 A second embodiment of the present invention will be described below. Elements having the same or corresponding functions and configurations as those in the first embodiment are given the same reference numerals, and detailed description will be omitted. FIG. 4 is an explanatory diagram of a toner conveying device, showing the downstream internal configuration of waste toner conveying path 52 provided in the toner conveying device. A pipe 401 is provided in waste toner conveying path 52. A screw 405 is provided in the pipe (inside pipe 401). Screw 405, which is a conveying member, has a rotating shaft and is rotatable. Screw 405 has a rotating shaft portion 402 (small diameter shaft portion), a rotating shaft portion 403 (large diameter shaft portion), and a screw portion 404. Screw portion 404 is provided by being wound in a spiral shape around the outer periphery of rotating shaft portions 402 and 403. Screw portion 404 is a vane portion having a vane shape.

[0040] Screw 405 has a first screw portion formed by screw portion 404 and rotating shaft portion 402, and a second screw portion formed by screw portion 404 and rotating shaft portion 403. The first screw portion (screw portion 404 and rotating shaft portion 402) of screw 405 is disposed on the upstream side in the waste toner transport direction (upstream side of waste toner transport path 52) of a point where the cross-sectional area of ​​waste toner transport path 52 changes (cross-sectional area change point). The second screw portion (screw portion 404 and rotating shaft portion 403) of screw 405 is disposed on the upstream side in the waste toner transport direction (upstream side of waste toner transport path 52) of a point where the cross-sectional area of ​​waste toner transport path 52 changes (cross-sectional area change point). 3) is disposed downstream in the waste toner transport direction (downstream of waste toner transport path 52) with respect to the cross-sectional area change point.

[0041] The outer diameter (screw outer diameter) of the screw portion 404 is φDa1'. Therefore, the outer diameter (diameter) of the screw 405 is φDa1'. In addition, the outer diameter of the first screw portion of the screw 405 and the outer diameter of the second screw portion of the screw 405 are both φDa1'. 1 / 2 of the outer diameter (φDa1') of the first screw portion of the screw 405 is the distance from the rotation center line of the rotating shaft portion 402 to the outer circumferential end of the screw portion 404. 1 / 2 of the outer diameter (φDa1') of the second screw portion of the screw 405 is the distance from the rotation center line of the rotating shaft portion 403 to the outer circumferential end of the screw portion 404. The rotating shaft portion 402 and the rotating shaft portion 403 are formed so that the outer diameter (φd2') of the rotating shaft portion 403 is larger than the outer diameter (φd1') of the rotating shaft portion 402 (φd1'<φd2').

[0042] A piping 401 (pipe portion) having an inner diameter of φDb1′ corresponding to the outer diameter of the screw 405 is provided around the screw 405. A hole 406 serving as a discharge port (opening) is provided at an end of the piping 401, and the hole 406 is disposed downstream of the waste toner transport path 52.

[0043] The screw 405 extends to the vicinity of the hole 406 of the pipe 401. That is, the second screw portion of the screw 405 is disposed in the vicinity of the hole 406 of the pipe 401. In FIG. 4, the vicinity of the hole 406 of the pipe 401 includes an area overlapping with the hole 406 and a peripheral area of ​​the area overlapping with the hole 406 when viewed from a direction perpendicular to the rotation axis direction of the screw 405. In FIG. 4, the hole 406 is provided in the pipe 401 so as to face the direction perpendicular to the rotation axis direction of the screw 405. When viewed from a direction perpendicular to the rotation axis direction of the screw 405, the screw 405 extends to the vicinity of the hole 406 so that a part of the screw 405 (the second screw portion) and a part of the hole 406 overlap. Not limited to the configuration of FIG. 4, the screw 405 and the hole 406 may not overlap when viewed from a direction perpendicular to the rotation axis direction of the screw 405. Furthermore, hole 406 may be provided in pipe 401 so as to face the rotation axis direction of screw 405. In this case, screw 405 extends close to hole 406 so that a part of screw 405 (second screw portion) and a part of hole 406 overlap when viewed from the rotation axis direction of screw 405. This configuration is not limited to this, and screw 405 and hole 406 may not overlap when viewed from the rotation axis direction of screw 405.

[0044] The waste toner transported to waste toner transport path 52 is pushed out toward waste toner transport path 53 through hole 406 of pipe 401. That is, the waste toner is discharged from hole 406 of pipe 401 by the rotation of screw 405. Therefore, hole 406 is an outlet for discharging the waste toner in pipe 401. When the waste toner is transported into waste toner transport path 52, the waste toner is distributed in area A2 indicated by diagonal hatching in FIG. 4 within waste toner transport path 52, and the area (neighboring area) near hole 406 in waste toner transport path 52 becomes filled with waste toner.

[0045] Waste toner transport path 53 (second transport path) is connected to hole 406 of pipe 401. Waste toner flows into waste toner transport path 53 through hole 406. Hole 406 can also be considered a communication port that connects waste toner transport path 52 and waste toner transport path 53. When waste toner that has flowed into waste toner transport path 53 is transported vertically upward, the area in waste toner transport path 52 near hole 406 is filled with waste toner. In this state, the graph shown in FIG. 4 shows the effective cross-sectional area of ​​the transport path and the pressure applied to the waste toner, with the horizontal axis representing the position in the waste toner transport direction.

[0046] Here, the effective cross-sectional area of ​​the conveying path will be described. The effective cross-sectional area of ​​the region in which the first screw portion of the screw 405 in the pipe 401 is arranged is the area obtained by subtracting the cross-sectional area of ​​the rotating shaft portion 402 in the orthogonal direction from the cross-sectional area of ​​the pipe 401 in the direction perpendicular to the rotation axis direction of the screw 405 (orthogonal direction). That is, the effective cross-sectional area of ​​the region in which the first screw portion of the screw 405 in the pipe 401 is arranged (the effective cross-sectional area of ​​the first portion of the pipe 401) is the cross-sectional area in the orthogonal direction of the space formed between the inner wall 401a of the pipe 401 and the rotating shaft portion 402 of the screw 405. The effective cross-sectional area of ​​the region in which the second screw portion of the screw 405 in the pipe 401 is arranged is the area obtained by subtracting the cross-sectional area of ​​the rotating shaft portion 403 in the orthogonal direction from the cross-sectional area of ​​the pipe 401 in the direction perpendicular to the rotation axis direction of the screw 405 (orthogonal direction). That is, the effective cross-sectional area of ​​the region in which the second screw portion of the screw 405 in the pipe 401 is disposed (the effective cross-sectional area of ​​the second portion of the pipe 401) is the cross-sectional area in the perpendicular direction of the space formed between the inner wall 401a of the pipe 401 and the rotation shaft portion 403 of the screw 405. The effective cross-sectional area of ​​the waste toner transport path 52 is the effective cross-sectional area of ​​the first portion of the pipe 401 or the effective cross-sectional area of ​​the second portion of the pipe 401.

[0047] In the second embodiment, the outer diameter (φDa1′) of the screw 405 is not changed, and the diameter of the rotation shaft of the screw 405 is increased. As in the first embodiment, when the effective cross-sectional area of ​​the transport path is graphed, as shown in FIG. 4, the effective cross-sectional area of ​​the transport path on the downstream side in the waste toner transport direction can be made smaller than the effective cross-sectional area of ​​the transport path on the upstream side in the waste toner transport direction, with the cross-sectional area change point as a boundary. For example, the effective cross-sectional area (effective cross-sectional area of ​​the second part of the pipe 401) in the vicinity of the hole 406 in the waste toner transport path 52 is smaller than the effective cross-sectional area (effective cross-sectional area of ​​the first part of the pipe 401) in the waste toner transport path 52 other than the vicinity of the hole 406. Therefore, the pressure applied to the waste toner is the same mechanism as that described in the first embodiment, and when the waste toner is transported vertically upward, the necessary inflow pressure to the waste toner transport path 53 can be efficiently generated, as in the first embodiment. Therefore, the toner transport efficiency on the downstream side of the toner transport path can be improved. In addition, it is possible to improve the efficiency of toner transport in the toner transport path where the downstream side is more affected by gravity than the upstream side. By moving the retention start point closer to the discharge port (hole 406) of waste toner transport path 52, the area where pressure is applied to the waste toner is reduced, and the time that the waste toner passes through waste toner transport path 52 is reduced. This reduces damage to the waste toner.

[0048] Comparing Example 2 with Example 1, by making the effective cross-sectional area of ​​the transport path the same, the same effect can be expected in terms of mechanism. When adjusting the shape of the screw or the parts on the outer periphery of the screw depending on the flow rate and conditions of the waste toner, in Example 2, it is only necessary to change the screw. Therefore, when such a purpose is required, it is preferable to adopt the configuration of Example 2. In this example, the outer diameter of the screw is constant, but it is also possible to adjust the effective cross-sectional area of ​​the transport path by combining Examples 1 and 2, and the same effect can be obtained. Also, as in Example 1, the same effect can be obtained in a configuration that transports not only waste toner but also powder such as toner before development. [Explanation of symbols]

[0049] 52...waste toner transport path; 101, 102...pipe portion; 101a, 102a, 401a...inner wall; 103, 406...hole portion; 104, 401...piping; 202, 405...screw

Claims

1. a first transport unit including: a first tube; a first screw provided within the first tube and rotatable about a rotation axis; an opening provided on a side surface of the first tube extending in the direction of the rotation axis, the opening being located downstream of the first tube in a toner transport direction by the first screw; and an end surface of the first tube that is located downstream of the opening in the toner transport direction and intersects with the rotation axis; a second transport unit including: a second tube connected to the first tube such that an interior of the second tube communicates with the opening of the first tube and extending upward; and a second screw provided within the second tube and configured to transport the toner received through the opening of the first tube upward; A drive unit for supplying a drive force for rotating the first screw and the second screw; A toner conveying device comprising: The first screw extends so as to overlap with the opening when viewed in a direction perpendicular to the rotation axis, a downstream end of the first screw is located upstream of the end surface of the first tube in the toner transport direction; The first screw has a rotating shaft portion centered on the rotation axis and a helical portion provided on the outer periphery of the rotating shaft portion in a radial direction of the rotating shaft portion centered on the rotation axis, and is configured so that the downstream tip does not have a portion that protrudes outward from an outermost diameter portion of the helical portion in the radial direction. A toner transport device comprising:

2. 2. The toner transport device according to claim 1, wherein the downstream end of the first screw is located upstream of the downstream end of the opening in the toner transport direction.

3. an inner diameter of a first portion of the first tube, which includes a first region overlapping with the opening when viewed in a direction perpendicular to the rotation axis and a second region adjacent to the first region on the upstream side in the toner transport direction, is smaller than an inner diameter of a second portion of the first tube, which includes a third region adjacent to the second region on the upstream side in the toner transport direction and adjacent to the first region on the upstream side in the toner transport direction; a length of the first portion is shorter than a length of the second portion in the toner transport direction; With respect to a cross-sectional area perpendicular to the rotation axis of a space formed between an inner wall of the first tube and the first screw, the cross-sectional area at a position corresponding to the first portion in the direction of the rotation axis is smaller than the cross-sectional area at a position corresponding to the second portion in the direction of the rotation axis.

2. The toner transport device according to claim 1,

4. 4. The toner conveying device according to claim 3, wherein an outer diameter of a third portion of the first screw corresponding to a first portion of the first tube in the direction of the rotation axis is smaller than an outer diameter of a fourth portion of the first screw corresponding to a second portion of the first tube in the direction of the rotation axis.

5. A toner conveying device as described in claim 3, characterized in that the outer diameter of a third part of the rotating shaft portion corresponding to the first part of the first tube in the direction of the rotation axis is smaller than the outer diameter of a fourth part of the rotating shaft portion corresponding to the second part in the direction of the rotation axis.

6. A toner conveying device as described in claim 3, characterized in that the outer diameter of a third part of the rotating shaft portion corresponding to the first part of the first tube in the direction of the rotation axis is larger than the outer diameter of a fourth part of the rotating shaft portion corresponding to the second part in the direction of the rotation axis.

7. 7. The toner transport device according to claim 5, wherein the spiral portion makes at least one revolution around the rotation shaft portion in the first portion of the first tube.

8. 2. The toner transport device according to claim 1, wherein the opening faces a horizontal direction.

Images