Powder conveying apparatus and image forming apparatus

Abstract

To provide a conveying screw capable of suppressing aggregation of powder and reduction in conveying performance on a downstream side in a powder conveying direction, and to provide a powder conveying device and an image forming device.SOLUTION: A nozzle conveying screw 164, or a conveying screw, comprises a shaft 164b, or a shaft portion, and a blade 164a, or blade portion, spirally wound around the shaft 164b, and is configured to convey powdery toner T. The nozzle conveying screw 164 has through-holes 164c provided at positions identical in a rotating direction of the blade 164a.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention ,powder relates to a body transfer device and an image forming apparatus.

Background Art

[0002] Conventionally, a conveying screw having a shaft portion and blade portions spirally wound around the shaft portion and conveying powder toward one end portion of the blade portions is known.

[0003] Patent Document 1 describes a conveying screw provided with two notch portions reaching the shaft portion of the conveying screw in the blade portions in the downstream region in the conveying direction of toner as the powder. The two notch portions are provided at the same position in the rotational direction of the conveying screw.

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in Patent Document 1, no notch is formed in the blade portion in the upstream region in the toner conveying direction, and the internal pressure on the downstream side in the powder conveying direction of the conveying path in which the conveying screw is disposed increases, and there is a risk that powder aggregation and deterioration of conveying performance occur on the downstream side in the powder conveying direction.

Means for Solving the Problems

[0005] In order to solve the above-described problems, the present invention provides a powder conveying apparatus including a conveying screw inside and a conveying path for rotating the conveying screw to convey powder, The powder is toner, the transport path is cylindrical, and the transport path is configured such that air inside the transport path flows to the outside only from the upstream and downstream ends in the powder transport direction. where the conveying screw includes a shaft portion and blade portions spirally wound around the shaft portion, and through holes or notches are provided at all the same positions in the rotational direction of the blade portions, and the through holes or notches are located in an air layer vertically above the shaft portion in the conveying path, and the rotation of the conveying screw is stopped so as to be positioned.

Effects of the Invention

[0006] According to the present invention, it is possible to suppress powder aggregation and a decrease in conveyance performance on the downstream side in the powder conveying direction. [Brief explanation of the drawing]

[0007] [Figure 1] A schematic diagram of the copier according to this embodiment. [Figure 2] A schematic diagram showing the general configuration of the image-making unit corresponding to yellow. [Figure 3] (a) is a perspective view showing the toner container installed in the toner supply device, and (b) is a schematic diagram. [Figure 4] A schematic diagram of a conveying nozzle equipped with a conventional nozzle conveying screw. [Figure 5] A schematic diagram of a transport nozzle equipped with a nozzle transport screw according to this embodiment. [Figure 6] A schematic diagram of a transport nozzle equipped with a modified nozzle transport screw. [Figure 7] A diagram illustrating the placement of through holes or notches. [Figure 8] A diagram illustrating the same position in the rotational direction of through-holes or notches in the blades. [Figure 9] A schematic diagram showing an example of a nozzle transport screw configuration in which through holes are provided at positions different in the direction of rotation of the blades. [Figure 10] A schematic diagram showing an example of a nozzle transport screw in which multiple rows of through holes, each located at the same position in the direction of blade rotation, are provided in the direction of rotation. [Figure 11] A schematic diagram showing an example of nozzle transport screw configuration when there is one location where the gap between the transport screw blades at the top of the transport nozzle and the inner wall of the transport nozzle may be filled by toner adhering to the inner wall. [Figure 12] A schematic diagram showing an example of a nozzle transport screw configuration when there are two locations where the gap between the transport screw blades at the top of the transport nozzle and the inner wall of the transport nozzle may be filled by toner adhering to the inner wall. [Modes for carrying out the invention]

[0008] The following describes one embodiment of the present invention in which the present invention is applied to a photocopier (hereinafter referred to as photocopier 500) as an image forming apparatus. Figure 1 is a schematic diagram of the copier 500 of this embodiment. The copier 500 consists of a copier unit body (hereinafter referred to as the printer unit 100), a paper feed table (hereinafter referred to as the paper feed unit 200), and a scanner (hereinafter referred to as the scanner unit 400) mounted on the printer unit 100.

[0009] The toner container housing section 70, located at the top of the printer unit 100, contains four developer housing containers corresponding to each color (yellow, magenta, cyan, and black). These toner containers 32 (Y, M, C, K), which are powder containers, are detachably installed (replaceable). An intermediate transfer unit 85 is located below the toner container housing section 70.

[0010] The intermediate transfer unit 85 consists of an intermediate transfer belt 48, four primary transfer bias rollers 49 (Y, M, C, K), a secondary transfer backup roller 82, multiple tension rollers, and an intermediate transfer cleaning device, etc. The intermediate transfer belt 48 is stretched and supported by multiple roller members, and moves endlessly in the direction of the arrow in Figure 1 by the rotational drive of the secondary transfer backup roller 82, which is one of these multiple roller members.

[0011] In the printer unit 100, four image-forming units 46 (Y, M, C, K), which correspond to each color, are arranged side by side opposite the intermediate transfer belt 48. Below the four toner containers 32 (Y, M, C, K), four toner supply devices 60 (Y, M, C, K), corresponding to each container, are arranged. The toner contained in the toner containers 32 (Y, M, C, K) is supplied (replenished) by the corresponding toner supply devices 60 (Y, M, C, K) into the developing devices (powder-using units), which are the developing means of the image-forming units 46 (Y, M, C, K) corresponding to each color.

[0012] Furthermore, as shown in Figure 1, the printer unit 100 is equipped with an exposure device 47, which is a latent image forming means, below the four image forming units 46. The exposure device 47 exposes the surface of the photoreceptor 41 (described later) based on the image information of the original image read by the scanner unit 400 or image information input from an external device such as a personal computer, and forms an electrostatic latent image on the surface of the photoreceptor 41. The exposure device 47 in the printer unit 100 uses a laser beam scanner method using a laser diode, but other configurations such as using an LED array as the exposure means are also acceptable.

[0013] Figure 2 is a schematic diagram showing the general configuration of the image-forming unit 46Y corresponding to yellow. The image-forming unit 46Y includes a drum-shaped photoreceptor 41Y, which is an image carrier. Furthermore, the image-forming unit 46Y is configured with a charging roller 44Y, a developing device 50Y, a photoreceptor cleaning device 42Y, an anti-static device, etc., arranged around the photoreceptor 41Y. The image-forming process (charging process, exposure process, developing process, transfer process, cleaning process) is then performed on the photoreceptor 41Y to form a yellow image on the photoreceptor 41Y.

[0014] Furthermore, the other three image-forming units 46(M,C,K) have almost the same configuration as the image-forming unit 46Y corresponding to yellow, except that the color of the toner used is different, and an image of the color corresponding to the respective toner is formed on each photoreceptor 41(M,C,K). Below, we will omit the explanations of the other three image-forming units 46(M,C,K) as appropriate and only explain the image-forming unit 46Y corresponding to yellow.

[0015] The photoreceptor 41Y is rotationally driven in the clockwise direction in Fig. 2 by a drive motor. And at a position facing the charging roller 44Y, the surface of the photoreceptor 41Y is uniformly charged (charging process). Then, the surface of the photoreceptor 41Y reaches the irradiation position of the laser beam L emitted from the exposure device 47, and an electrostatic latent image corresponding to yellow is formed by exposure scanning at this position (exposure process). Then, the surface of the photoreceptor 41Y reaches the position facing the developing device 50Y, and the electrostatic latent image is developed at this position to form a yellow toner image (developing process).

[0016] The four primary transfer bias rollers 49 (Y, M, C, K) of the intermediate transfer unit 85 sandwich the intermediate transfer belt 48 between the photoreceptors 41 (Y, M, C, K) to form a primary transfer nip. And a transfer bias opposite to the polarity of the toner is applied to the primary transfer bias roller 49 (Y, M, C, K).

[0017] The surface of the photoreceptor 41Y on which the toner image is formed in the developing process reaches the primary transfer nip facing the primary transfer bias roller 49Y with the intermediate transfer belt 48 interposed therebetween, and the toner image on the photoreceptor 41Y is transferred onto the intermediate transfer belt 48 at this primary transfer nip (primary transfer process). At this time, a small amount of untransferred toner remains on the photoreceptor 41Y. The surface of the photoreceptor 41Y where the toner image is transferred to the intermediate transfer belt 48 at the primary transfer nip reaches the position facing the photoreceptor cleaning device 42Y. At this facing position, the untransferred toner remaining on the photoreceptor 41Y is mechanically recovered by the cleaning blade 42a (cleaning process). Finally, the surface of the photoreceptor 41Y reaches the position facing the charge eliminating device, and the residual potential on the photoreceptor 41Y is removed at this position. Thus, a series of image forming processes performed on the photoreceptor 41Y is completed.

[0018] This imaging process is carried out in the other imaging units 46(M,C,K) in the same way as in the yellow imaging unit 46Y. Specifically, a laser beam L based on image information is irradiated from an exposure device 47 located below the imaging units 46(M,C,K) onto the photoreceptors 41(M,C,K) of each imaging unit 46(M,C,K). More specifically, the exposure device 47 emits a laser beam L from a light source and irradiates each photoreceptor 41(M,C,K) via multiple optical elements while scanning the laser beam L with a rotating polygon mirror. After that, the toner images of each color formed on each photoreceptor 41(M,C,K) through the development process are transferred onto an intermediate transfer belt 48.

[0019] At this time, the intermediate transfer belt 48 travels in the direction of the arrow in Figure 1, sequentially passing through the primary transfer nips of each primary transfer bias roller 49 (Y, M, C, K). As a result, the toner images of each color on each photoreceptor 41 (Y, M, C, K) are superimposed onto the intermediate transfer belt 48 and primary transferred, forming a color toner image on the intermediate transfer belt 48.

[0020] The intermediate transfer belt 48, on which the toner images of each color are superimposed and transferred to form a color toner image, reaches a position opposite the secondary transfer roller 89. At this position, the secondary transfer backup roller 82 sandwiches the intermediate transfer belt 48 between itself and the secondary transfer roller 89, forming a secondary transfer nip. The color toner image formed on the intermediate transfer belt 48 is then transferred onto a recording medium P, such as transfer paper, which has been transported to the position of the secondary transfer nip. At this time, untransferred toner remains on the intermediate transfer belt 48 that has not been transferred to the recording medium P. After passing through the secondary transfer nip, the intermediate transfer belt 48 reaches the position of the intermediate transfer cleaning device, where the untransferred toner on its surface is collected, and the series of transfer processes performed on the intermediate transfer belt 48 are completed.

[0021] Next, we will explain the movement of the recording medium P. The recording medium P that is transported to the secondary transfer nip described above is transported from the paper feed tray 26 of the paper feed unit 200 located below the printer unit 100, via the paper feed roller 27 and the registration roller pair 28. Specifically, multiple recording mediums P are stored stacked in the paper feed tray 26. When the paper feed roller 27 is driven to rotate counterclockwise in Figure 1, the uppermost recording medium P is transported toward the roller nip formed by the two rollers of the registration roller pair 28.

[0022] The recording medium P, transported to the register roller pair 28, temporarily stops at the position of the roller nip of the register roller pair 28, where the rotational drive has been stopped. Then, in accordance with the timing that the color toner image on the intermediate transfer belt 48 reaches the secondary transfer nip, the register roller pair 28 is driven to rotate, and the recording medium P is transported toward the secondary transfer nip. As a result, the desired color toner image is transferred onto the recording medium P.

[0023] The recording medium P onto which the color toner image has been transferred by the secondary transfer nip is transported to the fuser unit 86. In the fuser unit 86, the color toner image transferred to the surface is fixed onto the recording medium P by heat and pressure from the fuser belt and pressure rollers. The recording medium P that has passed through the fuser unit 86 is discharged outside the device via the gap between the paper discharge roller pair 29. The recording medium P discharged outside the device by the paper discharge roller pair 29 is sequentially stacked on the stacking unit 30 as the output image. In this way, a series of image forming processes in the copier 500 is completed.

[0024] Next, the configuration and operation of the developing device 50 in the image-forming unit 46 will be explained in more detail. Here, the image-forming unit 46Y, which corresponds to yellow, will be used as an example, but the same applies to the image-forming units 46 of other colors (M, C, K).

[0025] As shown in Figure 2, the developing device 50Y consists of a developing roller 51Y, a doctor blade 52Y, two developer transport screws 55Y, and a toner density detection sensor 56Y. The developing roller 51Y faces the photoreceptor 41Y, and the doctor blade 52Y faces the developing roller 51Y. The two developer transport screws 55Y are arranged in two developer storage sections (53Y, 54Y). The developing roller 51Y consists of a magnetic roller fixed inside and a sleeve that rotates around the magnetic roller. The first developer storage section 53Y and the second developer storage section 54Y contain a two-component developer G consisting of a carrier and toner. The second developer storage section 54Y communicates with the outlet 66 of the toner supply device (see Figure 3) through an opening formed above it. The toner density detection sensor 56Y detects the toner density in the developer G in the second developer storage section 54Y.

[0026] The developer G in the developing apparatus 50 is agitated by two developer transport screws 55Y and circulates between the first developer storage section 53Y and the second developer storage section 54Y. The developer G in the first developer storage section 53Y is transported by one of the developer transport screws 55Y and supplied onto the sleeve surface of the developing roller 51Y by the magnetic field formed by the magnet roller in the developing roller 51Y, where it is supported. The sleeve of the developing roller 51Y is driven to rotate counterclockwise as shown by the arrow in Figure 2, and the developer G supported on the developing roller 51Y moves on the developing roller 51Y as the sleeve rotates. At this time, the toner in the developer G is charged to a potential opposite to that of the carriers due to triboelectric charging with the carriers in the developer G, and is electrostatically attracted to the carriers. Together with the carriers attracted by the magnetic field formed on the developing roller 51Y, it is supported on the developing roller 51Y.

[0027] The developer G supported on the developing roller 51Y is transported in the direction of the arrow in Figure 2 to the doctor section where the doctor blade 52Y and the developing roller 51Y face each other. As the developer G on the developing roller 51Y passes through the doctor section, its amount is adjusted to an appropriate level, and then it is transported to the developing region, which is the position opposite the photoreceptor 41Y. In the developing region, the toner in the developer G is adsorbed onto the latent image formed on the photoreceptor 41Y by the developing electric field formed between the developing roller 51Y and the photoreceptor 41Y. The developer G remaining on the surface of the developing roller 51Y after passing through the developing region reaches above the first developer storage section 53Y as the sleeve rotates, and at this position it is detached from the developing roller 51Y.

[0028] The developer G in the developing unit 50Y is adjusted so that the toner concentration is within a predetermined range. Specifically, according to the amount of toner consumed by developing the developer G contained in the developing unit 50Y, the toner contained in the toner container 32Y is replenished into the second developer storage unit 54Y via the toner replenishment device 60Y, which will be described later. The toner supplied to the second developer storage section 54Y is mixed and agitated with the developer G by two developer transport screws 55Y, and circulates between the first developer storage section 53Y and the second developer storage section 54Y.

[0029] The toner in each toner container 32 (Y, M, C, K) installed in the toner container storage section 70 of the printer unit 100 is replenished into each developer unit 50 (Y, M, C, K) as needed, according to the toner consumption in each developer unit 50 (Y, M, C, K). At this time, the toner in each toner container 32 (Y, M, C, K) is replenished by a toner replenishment device 60 (Y, M, C, K) provided for each toner color.

[0030] Next, we will explain the toner supply device 60 (Y, M, C, K). Figure 3(a) is a perspective view showing the toner container 32 installed in the toner supply device 60, which is a powder conveying device, and Figure 3(b) is a schematic diagram. The toner conveying direction of the relay conveying path 65 is actually perpendicular to the plane of the paper in Figure 3(b), but in Figure 3(b), the toner conveying direction of the relay conveying path 65 is shown as being the same as that of the conveying nozzle 61 for clarity. Furthermore, the four toner supply devices 60 (Y, M, C, K) and toner containers 32 (Y, M, C, K) are almost identical in structure except for the different colors of toner used in the imaging process. Therefore, the color codes Y, M, C, K will be omitted in the following explanation as appropriate.

[0031] The toner supply device 60 has a transport nozzle 61, a vertical transport path 64, and an intermediate transport path 65. When the toner container 32, which is a powder container, is installed in the toner container storage section 70 of the printer unit 100, the transport nozzle 61 of the toner supply device 60 is inserted from the front end of the toner container 32 in conjunction with the installation operation. This creates communication between the inside of the toner container 32 and the inside of the transport nozzle 61.

[0032] The toner container 32 is a roughly cylindrical toner bottle. It mainly consists of a container front cover 34 that is held non-rotatably in the toner container housing section 70 and a container body 33 on which a container gear 301 is integrally formed. The container body 33 is held so as to be rotatable relative to the container front cover 34.

[0033] When rotational drive is input from the drive device to the container gear provided in the container body 33, the container body 33 rotates. As the container body 33 rotates, the spiral projection 302 formed spirally on the inner circumferential surface of the container body 33 conveys the toner contained inside the container body 33 along the longitudinal direction of the container body toward the transport nozzle 61.

[0034] The container body 33 is provided with a pumping section on the container front cover side, which pumps up the toner that has been transported to the container front cover side by the rotation of the container body 33. This pumping section pumps the toner up above the transport nozzle 61 inserted into the toner container, and the toner falls into the nozzle opening 62, which serves as an intake port provided at the toner container side end of the transport nozzle 61, thereby supplying toner into the transport nozzle 61.

[0035] A nozzle transport screw 164 is located inside the transport nozzle 61. When rotational drive is input from the drive unit, the nozzle transport screw 164 rotates, transporting the toner supplied into the transport nozzle 61 horizontally. The downstream end of the transport nozzle 61 in the transport direction is connected to a vertical transport path 64, and the toner transported by the nozzle transport screw 164 falls along the vertical transport path 64 by its own weight to the relay transport path 65.

[0036] A relay conveying screw 165 is positioned within the relay conveying path 65. When rotational drive is input from the drive unit, the relay conveying screw 165 rotates, conveying the toner supplied to the relay conveying path 65 horizontally. An outlet 66 is provided at the downstream end of the relay conveying path 65 in the conveying direction. The toner conveyed by the relay conveying screw 165 falls by gravity from the outlet 66 and is replenished into the developing device 50.

[0037] Figure 4 is a schematic diagram of a transport nozzle 61 equipped with a conventional nozzle transport screw 164. The nozzle transport screw 164 has a shaft 164b and blades 164a that are spirally wrapped around the shaft 164b. In order to miniaturize the device and to reduce the area that the blades 164a of the nozzle transport screw 164 do not reach and reduce the amount of toner T that accumulates, it is desirable that the gap d between the transport nozzle 61 and the nozzle transport screw 164 be as narrow as possible. However, if the gap d is eliminated, the rotational load on the nozzle transport screw 164 will increase, so a gap of about 1 mm is necessary.

[0038] The transport nozzle 61 is not completely filled with toner T, and has an air layer at the top. The toner container 32 and the toner transport path (vertical transport path 64) downstream of the transport nozzle in the toner transport direction are in communication through the gap between the blades 164a of the transport screw at the top of the transport nozzle and the inner wall of the transport nozzle 61.

[0039] During the transport operation, the air inside the toner container 32 is transported along with the toner T towards the vertical transport path 64. Meanwhile, the air transported to the vertical transport path 64 along with the toner T flows back towards the toner container through the gap between the blades 164a of the transport screw at the top of the transport nozzle and the inner wall of the transport nozzle 61. This allows the internal pressure inside the toner supply device to be maintained uniformly.

[0040] However, toner pressed against the inner wall of the transport nozzle 61 by the top of the blade 164a adheres to the inner wall of the transport nozzle 61, and over time, the gap d between the blade 164a of the transport screw at the top of the transport path and the inner wall of the transport nozzle 61 may become filled. This toner Tx adhering to the inner wall blocks the air flowing back towards the toner container 32. If transport continues in this state, the internal pressure on the downstream side of the toner transport direction of the toner supply device 60 will rise, hindering the transport of toner T, which may cause toner transport failure or aggregation due to compression.

[0041] As described above, Patent Document 1 describes a device in which notches are provided at the same position in the rotational direction of the blades 164a in the downstream region of the toner transport direction. By providing notches, air from the downstream region of the toner transport direction can be moved to the upstream side through these notches. However, in Patent Document 1, notches are not provided on the blades 164a in the upstream region of the toner transport direction. Therefore, air from the downstream region of the toner transport direction does not flow back to the toner container 32, and the rise in internal pressure on the downstream side of the toner transport direction cannot be suppressed.

[0042] Figure 5 is a schematic diagram of a transport nozzle 61 equipped with a nozzle transport screw 164 according to this embodiment. In this embodiment, through holes 164c are provided at the same position in the rotational direction of the blades 164a of the nozzle transport screw 164. As a result, as shown in Figure 5, when the through holes 164c are located in the air layer A above the transport nozzle 61, communication is established from the downstream end to the upstream end in the toner transport direction via the through holes 164c. This creates an airflow within the transport nozzle that moves from the upstream end to the downstream end in the toner transport direction, as shown by the arrows in the figure. Therefore, even if the gap d between the blades 164a of the transport screw and the inner wall of the transport nozzle 61 is filled with toner Tx adhering to the inner wall of the upper part of the transport nozzle, the air in the toner container 32 that has been transported downstream in the toner transport direction of the transport nozzle 61 along with the toner T can be reversed through the through holes 164c and returned to the toner container 32.

[0043] Thus, in this embodiment, by providing through holes 164c at the same position in the rotational direction of the blades 164a of the nozzle transport screw 164, the rise in internal pressure downstream in the toner transport direction of the transport path of the toner supply device can be suppressed. Therefore, the toner T can be transported efficiently, and the occurrence of toner transport failures and aggregation due to compression can be suppressed.

[0044] Figure 6 is a schematic diagram of a transport nozzle 61 equipped with a modified nozzle transport screw 164. In this modified example, the nozzle transport screw 164 has notches 164d at all the same positions in the rotational direction of the blades 164a. In this modified example as well, when the notches 164d are located in the air layer A above the transport nozzle 61, the toner container 32 and the vertical transport path 64 are connected via the notches 164d. As a result, as shown by the arrows in the figure, air can be moved from the upstream end to the downstream end in the toner transport direction of the transport nozzle. Therefore, even if the gap d between the blades 164a of the transport screw and the inner wall of the transport nozzle 61 is filled by toner Tx adhering to the upper inner wall of the transport nozzle, the air in the toner container 32 that has been transported downstream in the toner transport direction of the transport nozzle 61 along with the toner T can be returned to the toner container 32 via the notches 164d. This prevents obstruction of toner transport and suppresses toner transport failures and aggregation due to compression.

[0045] Figure 7 illustrates the arrangement of the through-hole 164c or notch 164d. Figure 7(a) shows an example in which the blade 164a is provided with a through-hole 164c, and Figure 7(b) shows an example in which the blade 164a is provided with a notch 164d. As shown in Figure 7, through holes 164c and notches 164d are provided outside the radial center of the blade 164a. In this embodiment, the diameter of the transport nozzle 61 is reduced to miniaturize the device, and the interface of the toner layer is above the axis 164b of the nozzle transport screw 164. Therefore, the air layer A inside the transport nozzle is located outside the radial center of the blade 164a, and air can only move through the through hole 164c or notch 164d outside the radial center of the blade 164a. Thus, as shown in Figure 7, by providing the through hole 164c or notch 164d outside the radial center of the blade 164a, air can be moved effectively through the through hole 164c or notch 164d.

[0046] Furthermore, the notch in Patent Document 1 described above is formed all the way to the base of the blade, effectively dividing the blade. Because the blade is divided by this notch, toner is no longer transported by the blade at the notch, resulting in a decrease in the amount of toner transported per unit time. This can lead to insufficient toner being transported within a predetermined period, potentially causing a decrease in image density during continuous printing of high-area images. Increasing the rotation speed of the nozzle transport screw could compensate for the decrease in toner transport per unit time caused by the notch. However, this could increase frictional heat due to friction between the blade and toner, potentially causing the toner to aggregate.

[0047] In contrast, in this embodiment, through holes 164c and notches 164d are provided outside the radial center of the blade 164a, and the blade 164a exists inside the radial center of the blade 164a. As a result, toner can be transported by the blade even at the locations of the through holes and notches, and a decrease in the amount of toner transported per unit time can be suppressed. This makes it possible to transport a predetermined amount of toner to the developing device within a predetermined period without increasing the rotation speed of the slide transport screw.

[0048] Figure 8 illustrates the rotational position of the blade 164a in the through hole 164c or notch 164d. As shown in Figures 8(a) and (b), in this embodiment, if a portion of the through hole 164c or notch 164d overlaps when viewed from the axial direction, it is defined that the through hole 164c or notch 164d is at the same position in the rotational direction of the blade 164a.

[0049] Furthermore, in this embodiment, the nozzle transport screw 164 is controlled to stop so that the through hole 164c or notch 164d provided in the blade 164a is located vertically above the shaft 164b, as shown in Figures 5 and 6. Specifically, a rotation position detection means is provided to detect the rotational position of the nozzle transport screw 164, and the motor that rotates the nozzle transport screw 164 is stopped based on the detection result of this rotation position detection means. Known means can be used as the rotation position detection means, and for example, it can consist of a filler that rotates together with the nozzle transport screw and an optical sensor that detects the filler.

[0050] When the nozzle transport screw 164 is rotating, the through-hole 164c or notch 164d is located in the air layer A for only a short period of time. Therefore, there is a risk that the air on the downstream side in the toner transport direction may not be able to move sufficiently to the upstream side through the through-hole 164c or notch. Consequently, depending on the configuration of the device, the amount of air flowing upstream in the toner transport direction through the through-hole 164c or notch may be less than the amount of air transported together with the toner, and the rise in internal pressure on the downstream side in the toner transport direction may not be sufficiently suppressed.

[0051] On the other hand, by controlling the stopping of the nozzle transport screw 164 so that the through hole 164c or notch 164d provided in the blade 164a is located vertically above the shaft 164b, the through hole 164c or notch 164d can be positioned in the air layer A inside the transport nozzle 61 when stopped. As a result, when stopped, the air inside the toner container 32 that has been transported downstream in the toner transport direction of the transport nozzle 61 along with the toner T can be returned to the toner container 32 through the notch 164d. Therefore, the rise in internal pressure on the downstream side in the toner transport direction can be effectively suppressed.

[0052] In the above configuration, through holes 164c or notches 164d are provided at the same position in the rotational direction of the blades 164a of the nozzle transport screw 164. However, through holes 164c or notches 164d do not need to be provided on the blades facing the nozzle opening 62 or the vertical transport path 64. In other words, the configuration may be such that through holes 164c or notches 164d are provided at the same position in the rotational direction of the blades 164a within the region L shown in Figure 3, from the downstream end of the nozzle opening 62 of the transport nozzle 61 in the toner transport direction to the upstream end of the communication port to the vertical transport path 64. In such a configuration, when the through holes 164c or notches 164d are located in the air layer inside the transport nozzle, the toner container 32 and the vertical transport path 64 can be connected via the through holes 164c or notches 164d.

[0053] For example, if the transport nozzle 61 is not in a straight line, the airflow will be poor in the curved parts of the transport nozzle 61. In such cases where there are areas of poor airflow in the transport nozzle 61, it is preferable to provide multiple through holes 164c at different positions in the rotational direction on the blade portion of the transport nozzle 61 where the airflow is poor, as shown in Figure 9. This allows for a greater amount of air to move through the through holes 164c compared to the case where there is only one through hole 164c. Therefore, the poor airflow caused by the shape of the transport path can be compensated for by multiple through holes or notches, and the rise in internal pressure downstream in the toner transport direction can be effectively suppressed. Note that Figure 9 uses through holes 164c as an example, but notches may also be used.

[0054] Furthermore, the range of rotation of the notches provided in the vanes where the airflow in the conveyor path is poor may be made larger than the range of rotation of the other notches to increase the amount of air moving through the notches 164d. Alternatively, the through holes provided in the vanes where the airflow in the conveyor path is poor may be made longer in the rotational direction than the other through holes to increase the amount of air moving through the through holes.

[0055] Furthermore, as shown in Figure 10, multiple rows of through holes 164c, each located at the same position in the rotational direction of the blades 164a of the nozzle transport screw 164, may be provided in the rotational direction. By providing multiple rows of through holes 164c located at the same position in the rotational direction, the opportunities for air to move through the through holes can be increased, thereby enhancing the effect of suppressing the rise in internal pressure downstream in the toner transport direction.

[0056] Furthermore, by using the configuration shown in Figure 10, the time required for stopping the nozzle conveying screw 164 so that a row of through holes 164c, each located at the same position in the rotational direction of the blades 164a of the nozzle conveying screw 164, is positioned vertically above the axis 164b can be shortened. This is because, if there is only one row of through holes 164c, depending on the rotational position of this row at the start of the stop control, it may be necessary to rotate the nozzle conveying screw by more than 3 / 4 of a turn. In contrast, as shown in Figure 10, if the rows of through holes 164c are spaced 180° apart, it is possible to position any of the rows of through holes vertically above the axis 164b in less than 1 / 2 of a turn. Thus, the time required for stop control can be shortened. Note that the configuration shown in Figure 10 is a through hole, but it may also be a notch.

[0057] Furthermore, depending on the device configuration, there may be a portion of the toner transport direction where the gap d between the blades 164a of the transport screw at the top of the transport nozzle and the inner wall of the transport nozzle 61 is likely to be filled by toner Tx adhering to the inner wall. In such cases, as shown in Figures 11(a) and (b), through holes 164c or notches 164d may be provided only in the portion of the blades 164a corresponding to the area where the gap d between the blades 164a of the transport screw at the top of the transport nozzle and the inner wall of the transport nozzle 61 is likely to be filled by toner Tx adhering to the inner wall.

[0058] As a result, as shown by the arrow in Figure 11, in areas where the gap d between the blades 164a of the transport screw at the top of the transport nozzle and the inner wall of the transport nozzle 61 is filled with toner Tx adhering to the inner wall, air moves upstream in the toner transport direction through the through-hole 164c or notch 164d. On the other hand, in areas where there is little risk of the gap d between the blades 164a of the transport screw at the top of the transport nozzle and the inner wall of the transport nozzle 61 being filled with toner Tx adhering to the inner wall, air moves upstream in the toner transport direction through the gap between the blades 164a of the transport screw at the top of the transport nozzle and the inner wall of the transport nozzle 61. This suppresses the rise in internal pressure on the downstream side of the transport path of the toner supply device.

[0059] Furthermore, in the configuration shown in Figure 11, the through-hole 164c or notch 164d is located outside the radial center of the blade. Therefore, toner is transported by the blade 164a even at the locations where the through-hole 164c or notch 164d is provided, thereby suppressing a decrease in the amount of toner transported per unit time.

[0060] Figure 12 shows an example where there are two locations where the gap between the blades 164a of the conveying screw at the top of the conveying nozzle and the inner wall of the conveying nozzle 61 may be filled with toner Tx adhering to the inner wall. In this case, through holes or notches are provided at the locations of the blades corresponding to each location where filling may occur. Furthermore, depending on the position of the locations where filling may occur in the conveying direction, the rotational positions of each through hole or notch may not be the same, as shown in Figure 12.

[0061] In the above description, an example of applying the present invention to a nozzle transport screw 164 installed in the transport nozzle 61 was explained, but the present invention may also be applied to an intermediate transport screw 165. Furthermore, the present invention can also be applied to transport screws that transport waste toner removed by a cleaning device to a waste toner tank, or transport screws that transport developer in a developing device, etc.

[0062] The above is just one example; each of the following embodiments produces its own unique effects. (Aspect 1) In a conveying screw such as a nozzle conveying screw 164, which has a shaft portion such as a shaft 164b and a blade portion such as a blade 164a spirally wrapped around the shaft portion, and conveys powder such as toner toward one end of the blade portion, through holes 164c or notches 164d are provided at all the same positions in the rotational direction of the blade portion. Generally, there is a predetermined gap between the top of the conveyor screw blades and the inner wall of the conveying path, and the upper part of the conveying path is not filled with powder such as toner T. Therefore, under normal circumstances, air conveyed by the conveyor screw along with the powder escapes to the upstream side of the powder conveyance through the gap between the top of the conveyor screw blades and the inner wall of the conveying path at the top of the conveying path. However, with use over time, the powder adheres to the inner wall, and the gap between the top of the conveyor screw blades and the upper inner wall of the conveying path may become filled with powder. As a result, the air conveyed by the conveyor screw along with the powder has nowhere to go, the internal pressure on the downstream side in the powder conveyance direction of the conveying path increases, and there is a risk of powder aggregation and a decrease in conveyance performance on the downstream side in the powder conveyance direction. Patent Document 1 describes a conveying screw in which a notch is provided at the same position in the rotational direction of the blade portion in the region downstream of the powder conveying direction. By providing a notch, even if the gap between the top of the blade portion of the conveying screw and the upper inner wall of the conveying path is filled with powder adhering to the inner wall in the region downstream of the powder conveying direction, when the notch is located in the air layer above the powder layer in the conveying path, air can move from the downstream side to the upstream side in the powder conveying direction through the notch, allowing air to be released from the conveying path and suppressing the increase in internal pressure on the downstream side of the conveying path in the powder conveying direction. However, Patent Document 1 does not provide a notch in the region upstream of the blade portion in the powder conveying direction. Therefore, if the gap between the top of the blade portion of the conveying screw at the top of the conveying path and the inner wall of the conveying path is filled with powder adhering to the inner wall in the region upstream of the blade portion in the powder conveying direction, air in the conveying path cannot escape from the supply opening. As a result, there is a risk that the increase in internal pressure on the downstream side of the conveying path in the powder conveying direction cannot be suppressed. In contrast, in Embodiment 1, through holes or notches are provided at all the same positions in the rotational direction of the blade portion. As a result, when the locations of the blade portion with through holes or notches in the rotational direction are located in the air layer above the powder layer in the conveying path, communication is established from the downstream end in the powder conveying direction to the supply opening at the upstream end where the powder is supplied, via these through holes or notches. This allows air from the downstream side in the powder conveying direction to be moved to the supply opening via these through holes or notches, and air in the conveying path can be removed. Therefore, regardless of where in the powder conveying direction the gap between the top of the conveying screw blade portion at the top of the conveying path and the inner wall of the conveying path is filled by powder adhering to the inner wall, air in the powder path conveyed together with the powder by the conveying screw can be removed. As a result, the rise in internal pressure on the downstream side in the powder direction of the conveying path can be effectively suppressed over time, and powder aggregation and deterioration of conveyability can be suppressed on the downstream side in the powder conveying direction over time.

[0063] (Aspect 2) In a conveying screw such as a nozzle conveying screw 164 that conveys powder such as toner, the conveying screw comprises a shaft portion such as a shaft 164b and a blade portion such as a blade 164a that is spirally wound around the shaft portion, and a through hole or notch is provided outside the radial center of the blade portion. In Patent Document 1, the notch cuts out the entire blade, dividing it. In this way, when the blade is divided by the notch, powder such as toner is not conveyed by the blade at the notched area, and the amount of toner conveyed per unit time decreases. As a result, there is a risk that the predetermined amount of powder cannot be conveyed within the predetermined period. In contrast, in embodiment 2, through holes or notches are provided outside the radial center of the blade portion, and the blade portion is located inside the center. As a result, toner can be transported by the blade portion located inside the radial center even at the locations of the through holes or notches, thereby suppressing a decrease in the amount of toner transported per unit time. Furthermore, at least the air layer A within the conveying path is formed at the top of the conveying path. Therefore, by providing through holes or notches outside the radial center of the blade section, the through holes or notches can be positioned in the air layer A at the top of the conveying path, allowing air to move through the through holes or notches. This allows the air conveyed together with the powder by the conveying screw to be returned to the upstream side of the conveying path in the powder conveying direction through the through holes or notches, thereby suppressing the rise in internal pressure on the downstream side in the powder conveying direction. Thus, powder aggregation and a decrease in conveyability can be suppressed.

[0064] (Aspect 3) In embodiment 2, a plurality of through holes 164c or notches 164d are provided on the blade portion, such as the blade 164a. According to this, air can be moved smoothly from the downstream side to the upstream side in the powder conveying direction within the conveying path through the through-hole 164c or notch 164d.

[0065] (Aspect 4) In embodiment 3, the multiple through holes 164c or notches 164d are provided at the same position in the rotational direction of the blade portion, such as the blade 164a. According to this, as described in the embodiment, multiple through holes 164c or notches 164d can be simultaneously positioned in the air layer A at the top of the conveying path, and the downstream air can move upstream through the multiple through holes 164c or notches 164d. This effectively suppresses the rise in internal pressure on the downstream side of the conveying path.

[0066] (Appendix 5) In embodiment 1, the through hole 164c or notch 164d is provided outside the radial center of the blade portion, such as the blade 164a. According to this, as described in the embodiment, through holes or notches can be positioned in the air layer A at the top of the conveying path, and air can be moved through these through holes or notches. As a result, the air conveyed together with the powder by the conveying screw can be returned to the upstream side of the conveying path in the powder conveying direction through the through holes or notches, thereby suppressing the rise in internal pressure on the downstream side in the powder conveying direction. Therefore, powder aggregation and a decrease in conveyability can be suppressed. Furthermore, because the blade section is not divided, toner can be transported by the blades even in areas with through holes or notches, thus suppressing a decrease in the amount of toner transported per unit time.

[0067] (Aspect 6) In any of embodiments 1 to 5, a second through hole or notch is provided at a position different in the rotational direction from the position where the through hole 164c or notch 164d is provided. According to this, as explained using Figure 9, the location where the second through-hole or notch is provided increases the opportunities for air to move through the through-hole or notch. Therefore, air can be moved smoothly from the downstream side to the upstream side of the powder conveying system through the through-hole or notch at that location.

[0068] (Aspect 7) In embodiment 6, a plurality of second through holes or notches are provided, and the plurality of second through holes or notches are provided at the same position in the rotational direction of the blade portion. According to this, as explained using Figure 10, the opportunities for air movement through the multiple through holes 164c or notches 164d can be increased, thereby enhancing the effect of suppressing the rise in internal pressure downstream in the toner transport direction.

[0069] (Pattern 8) In a powder conveying device such as a toner supply device 60, which is equipped with a conveying screw such as a nozzle conveying screw 164 inside and a conveying path such as a conveying nozzle that conveys powder such as toner by rotating the conveying screw, any conveying screw from embodiment 1 to 7 was used as the conveying screw. According to this, it is possible to suppress the rise in internal pressure on the downstream side in the powder conveying direction of powder conveying devices such as the toner supply device 60, thereby suppressing powder aggregation and a decrease in conveying performance.

[0070] (Aspect 9) In embodiment 8, the rotation of the conveying screw, such as the nozzle conveying screw 164, is stopped so that the through hole 164c or notch 164d is located vertically above the shaft portion, such as the shaft 164b. According to this, as described in the embodiment, when the rotation of a conveying screw such as the nozzle conveying screw 164 stops, air on the downstream side in the powder conveying direction can be moved to the upstream side through the through hole 164c or notch. This effectively suppresses the rise in internal pressure on the downstream side in the powder conveying direction.

[0071] (Aspect 10) In an image forming apparatus comprising an image forming means for forming a toner image and a toner transport device such as a toner supply device 60 for transporting toner, the powder transport device described in embodiment 7 or 8 was used as the toner transport device. According to this, the toner can be transported efficiently. [Explanation of Symbols]

[0072] 32: Toner container 33: Container body 34: Cover on the tip side of the container 46: Imaging section 50: Developing equipment 60: Toner replenishment device 61: Conveyor nozzle 62: Nozzle opening 64: Vertical transport path 65: Relay transport path 66: Outlet 70: Toner container storage section 164: Nozzle conveying screw 164a: Feather 164b: Axis 164c: Through hole 164d: Notch 165: Relay conveying screw 500: Photocopier A: Air layer P: Recording medium T: Toner Tx: Toner adhering to the inner wall d: Gap between the top of the nozzle conveying screw blade and the inner wall of the conveying nozzle. [Prior art documents] [Patent Documents]

[0073] [Patent Document 1] Publication 2018-55047

Claims

1. In a powder conveying device equipped with a conveying screw inside and a conveying path for conveying powder by rotating the conveying screw, The aforementioned powder is toner, The aforementioned transport path is cylindrical, and is configured such that air inside the transport path flows to the outside only from the upstream and downstream ends in the powder transport direction. The transport screw comprises a shaft portion and a blade portion spirally wound around the shaft portion. Through holes or notches are provided at all of the same positions in the rotational direction of the aforementioned blade portion. A powder conveying apparatus characterized by stopping the rotation of the conveying screw so that the through hole or notch is located in an air layer vertically above the shaft portion within the conveying path.

2. In a powder conveying device equipped with a conveying screw inside and a conveying path for conveying powder by rotating the conveying screw, The aforementioned powder is toner, The aforementioned transport path is cylindrical, and is configured such that air inside the transport path flows to the outside only from the upstream and downstream ends in the powder transport direction. The transport screw comprises a shaft portion and a blade portion spirally wound around the shaft portion. A through hole or notch is provided outside the radial center of the aforementioned wing portion. A powder conveying apparatus characterized by stopping the rotation of the conveying screw so that the through hole or notch is located in an air layer vertically above the shaft portion within the conveying path.

3. In the powder conveying apparatus according to claim 2, A powder conveying device characterized in that a plurality of through holes or notches are provided in the blade portion.

4. In the powder conveying apparatus according to claim 3, A powder conveying device characterized in that multiple through holes or notches are provided at the same positions in the rotational direction of the blade portion.

5. In the powder conveying apparatus according to claim 1, The powder conveying device is characterized in that the through hole or notch is provided outside the radial center of the blade portion.

6. In the powder conveying apparatus according to claim 1 or 2, A powder conveying device characterized by having a second through hole or notch at a position different in the rotational direction from the position where the aforementioned through hole or notch is provided.

7. In the powder conveying apparatus according to claim 6, Multiple of the aforementioned second through holes or notches are provided. A powder conveying device characterized in that a plurality of second through holes or notches are provided at the same positions in the rotational direction of the blade portion.

8. An imaging method for creating a toner image, In an image forming apparatus equipped with a toner transport device for transporting toner, An image forming apparatus characterized in that the powder conveying device described in claim 1 or 2 is used as the toner conveying device.

Images