Conveying screw, powder conveying device and image forming apparatus

Abstract

To provide a conveying screw, a powder conveying device, and an image forming apparatus that can prevent aggregation of powder.SOLUTION: A conveying screw such as a nozzle conveying screw 164 comprises a shank 164a, and a main blade part 164b that is spirally wound on the shank 164a. A toner conveyance direction downstream side end being one end of the blade part is formed with fall-off prevention parts 164d as a step part raised by one step from an outer peripheral surface of the shank 164a in a direction separating from the center of the shank 164a. The fall-off prevention parts 164d are formed outside, in a circumferential direction, of an area Z that is from one end of the main blade part 164b to a position advanced from the one end by a predetermined distance to the downstream side in the direction of rotation of the conveying screw.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a conveying screw, a powder conveying device, and an image forming apparatus. [Background technology]

[0002] BACKGROUND ART Conventionally, a conveying screw that includes a shaft portion and a blade portion spirally wound around the shaft portion and that conveys powder has been known.

[0003] Patent Document 1 describes a conveying screw having an eccentric portion on the shaft at a connection point with the vertical conveying path downstream in the powder conveying direction of the blade portion, on which a swinging member swinging within the vertical conveying path is hooked. A part of this eccentric portion is eccentric so as to protrude from the shaft. The part of this eccentric portion protruding from the shaft forms a step portion that is one step higher than the outer circumferential surface of the shaft in a direction away from the center of the shaft. One end of the blade portion, which is the downstream end of the powder conveying direction, is connected to the upstream end of the eccentric portion in the powder conveying direction. Summary of the Invention [Problem to be solved by the invention]

[0004] However, there is a risk of powder agglomeration on the downstream side in the rotation direction of the conveying screw at the connection point between one end of the blade, such as the downstream end of the blade in the powder conveyance direction, and a step portion, such as an eccentric portion. [Means for solving the problem]

[0005] In order to solve the above-mentioned problems, the present invention provides a conveying screw that includes a shaft portion and a blade portion that is spirally wound around the shaft portion and conveys powder toward one end of the blade portion, wherein one end of the blade portion has a portion that protrudes from the outer peripheral surface of the shaft portion. Te radicaland a drop prevention portion is provided at both axial ends of the eccentric portion to prevent the swinging member, which projects from the eccentric portion and is hooked onto the eccentric portion, from dropping off from the eccentric portion, the drop prevention portion being provided around the entire circumference of the shaft portion, one end of the blade portion being connected to the drop prevention portion, and extending from one end of the blade portion to a position a predetermined distance downstream in the rotation direction of the conveying screw on the shaft portion between the side surface of the blade portion on the downstream side in the rotation direction of the conveying screw and the end face of the drop prevention portion formed on the end of the eccentric portion on the blade portion side on the upstream side in the powder conveying direction. territory The outer diameter dimension of the shaft portion outside the region is gradually increased from the downstream side in the direction of rotation of the conveying screw so that the outer diameter dimension of the region is the same as the outer diameter dimension of the anti-fall-out portion. [Effects of the Invention]

[0006] According to the present invention, it is possible to suppress the aggregation of powder. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram illustrating the configuration of a copying machine according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram showing the general configuration of an imaging unit corresponding to yellow. [Figure 3] FIG. 2A is a perspective view showing a state in which a toner container is installed in a toner supply device, and FIG. 2B is a schematic view. [Figure 4] FIG. 4 is a cross-sectional view showing a part of the conveying nozzle and nozzle conveying screw, and a vertical conveying path. [Figure 5] FIG. 10 is a schematic diagram of a conventional nozzle conveying screw. [Figure 6] FIG. 10 is a diagram showing toner aggregated in a wedge-shaped region. [Figure 7] FIG. 2 is a diagram showing a characteristic part of the nozzle conveying screw of the first embodiment. [Figure 8] 3 shows another configuration example of the first embodiment. [Figure 9] 4 is a diagram illustrating the circumferential position of an area X that protrudes from the shaft portion of the eccentric portion. FIG. [Figure 10]FIG. 10 is a diagram showing a characteristic part of the nozzle conveying screw of the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] An embodiment of the present invention will be described below in which the present invention is applied to a copying machine (hereinafter referred to as copying machine 500) as an image forming apparatus. 1 is a schematic diagram of a copier 500 according to this embodiment. The copier 500 is made up of a copier main body (hereinafter referred to as a printer unit 100), a paper feed table (hereinafter referred to as a paper feed unit 200), and a scanner (hereinafter referred to as a scanner unit 400) attached to the printer unit 100.

[0009] Four developer containers corresponding to the respective colors (yellow, magenta, cyan, and black), that are also powder containers, are detachably (replaceably) installed in the toner container storage section 70 provided at the top of the printer section 100. An intermediate transfer unit 85 is disposed below the toner container storage section 70.

[0010] The intermediate transfer unit 85 is composed 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, 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 FIG. 1 by the rotational drive of the secondary transfer backup roller 82, which is one of the multiple roller members.

[0011] In the printer unit 100, four image forming units 46 (Y, M, C, K) which are image forming means corresponding to each color are arranged side by side so as to face the intermediate transfer belt 48. In addition, four toner supply devices 60 (Y, M, C, K) corresponding to the four toner containers 32 (Y, M, C, K) are arranged below the four toner containers 32 (Y, M, C, K). 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 developing means of the image forming units 46 (Y, M, C, K) corresponding to each color.

[0012] 1, the printer unit 100 also includes an exposure device 47, which is a latent image forming means, below the four image creating units 46. The exposure device 47 exposes the surface of a photoreceptor 41, which will be described later, based on image information of an original image read by the scanner unit 400 or image information input from an external device such as a personal computer, thereby forming an electrostatic latent image on the surface of the photoreceptor 41. The exposure device 47 included in the printer unit 100 uses a laser beam scanner system that uses a laser diode, but other configurations such as an LED array may also be used as the exposure means.

[0013] FIG. 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 photoconductor 41Y that serves as an image carrier. The image forming unit 46Y also includes a charging roller 44Y that serves as a charging means, a developing device 50Y that serves as a developing means, a photoconductor cleaning device 42Y, a static eliminator, and other devices that are arranged around the photoconductor 41Y. An image forming process (charging step, exposure step, development step, transfer step, and cleaning step) is then performed on the photoconductor 41Y, forming a yellow image on the photoconductor 41Y.

[0014] The other three image forming units 46 (M, C, K) have substantially the same configuration as the image forming unit 46Y corresponding to yellow, except that they use different toner colors, and form images of the colors corresponding to the respective toners on the respective photoconductors 41 (M, C, K). Below, we will omit the description of the other three image forming units 46 (M, C, K) as appropriate, and will only describe the image forming unit 46Y corresponding to yellow.

[0015] The photoreceptor 41Y is driven to rotate in the clockwise direction in FIG. 2 by a drive motor. Then, the surface of the photoreceptor 41Y is uniformly charged at a position facing the charging roller 44Y (charging process). Thereafter, the surface of the photoreceptor 41Y reaches a position irradiated with laser light 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). Thereafter, the surface of the photoreceptor 41Y reaches a 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 themselves and the photosensitive members 41 (Y, M, C, K), forming primary transfer nips. A transfer bias opposite to the polarity of the toner is applied to the primary transfer bias rollers 49 (Y, M, C, K).

[0017] The surface of the photoreceptor 41Y, on which the toner image has been formed in the development process, reaches a primary transfer nip facing the primary transfer bias roller 49Y across the intermediate transfer belt 48. The toner image on the photoreceptor 41Y is transferred to 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, which has transferred the toner image to the intermediate transfer belt 48 at the primary transfer nip, reaches a position facing the photoreceptor cleaning device 42Y. At this position, the untransferred toner remaining on the photoreceptor 41Y is mechanically collected by the cleaning blade 42a (cleaning process). Finally, the surface of the photoreceptor 41Y reaches a position facing the static eliminator, where the residual potential on the photoreceptor 41Y is removed. This completes the series of image formation processes performed on the photoreceptor 41Y.

[0018] This image formation process is also performed in the other image forming units 46 (M, C, K) in the same manner as in the yellow image forming unit 46Y. That is, laser light L based on image information is irradiated onto the photoconductors 41 (M, C, K) of each image forming unit 46 (M, C, K) from an exposure device 47 disposed below the image forming unit 46 (M, C, K). More specifically, the exposure device 47 emits laser light L from a light source, and irradiates each photoconductor 41 (M, C, K) with the laser light L via multiple optical elements while scanning with a rotationally driven polygon mirror. Thereafter, the toner images of each color formed on each photoconductor 41 (M, C, K) undergo a development process and are transferred onto an intermediate transfer belt 48.

[0019] 1, and sequentially passes through the primary transfer nips of the primary transfer bias rollers 49 (Y, M, C, K). As a result, the toner images of each color on the photoconductors 41 (Y, M, C, K) are primarily transferred onto the intermediate transfer belt 48 in a superimposed manner, and a color toner image is formed on the intermediate transfer belt 48.

[0020] The toner images of each color are transferred one on top of the other, and the intermediate transfer belt 48, on which a color toner image is formed, reaches a position facing a secondary transfer roller 89. At this position, a secondary transfer nip is formed by sandwiching the intermediate transfer belt 48 between the secondary transfer backup roller 82 and the secondary transfer roller 89. The color toner image formed on the intermediate transfer belt 48 is then transferred onto a recording medium P, such as transfer paper, that has been transported to the position of the secondary transfer nip. At this time, untransferred toner that has not been transferred to the recording medium P remains on the intermediate transfer belt 48. After passing through the secondary transfer nip, the intermediate transfer belt 48 reaches the position of an intermediate transfer cleaning device, where the untransferred toner on its surface is collected, thereby completing the series of transfer processes that take place on the intermediate transfer belt 48.

[0021] Next, the movement of the recording medium P will be described. The recording medium P transported to the secondary transfer nip is transported from a paper feed tray 26 of a paper feed unit 200 disposed below the printer unit 100 via a paper feed roller 27 and a pair of registration rollers 28. More specifically, a plurality of recording media P are stored in a stack in the paper feed tray 26. When the paper feed roller 27 is driven to rotate counterclockwise in FIG. 1, the topmost recording medium P is transported toward the roller nip formed by the two rollers of the pair of registration rollers 28.

[0022] The recording medium P conveyed to the registration roller pair 28 stops temporarily at the roller nip position of the registration roller pair 28, which has stopped rotating. Then, in synchronization with the timing at which the color toner image on the intermediate transfer belt 48 reaches the secondary transfer nip, the registration roller pair 28 is rotated and the recording medium P is conveyed toward the secondary transfer nip. In this way, 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 at the secondary transfer nip is transported to the position of the fixing device 86. In the fixing device 86, the color toner image transferred onto the surface is fixed onto the recording medium P by the heat and pressure of the fixing belt and pressure roller. After passing through the fixing device 86, the recording medium P passes between the rollers of the paper discharge roller pair 29 and is discharged to the outside of the apparatus. The recording medium P discharged to the outside of the apparatus by the paper discharge roller pair 29 is stacked in order on the stack unit 30 as an output image. In this way, a series of image formation processes in the copier 500 is completed.

[0024] Next, a more detailed description will be given of the configuration and operation of the developing device 50 in the image forming unit 46. Note that, although the description will be given here using the image forming unit 46Y corresponding to yellow as an example, the same applies to the image forming units 46 for the other colors (M, C, K).

[0025] As shown in FIG. 2, the developing device 50Y is composed of a developing roller 51Y, a doctor blade 52Y, two developer transport screws 55Y, and a toner concentration detection sensor 56Y. The developing roller 51Y faces the photoconductor 41Y, and the doctor blade 52Y faces the developing roller 51Y. The two developer transport screws 55Y are disposed in two developer containers (53Y, 54Y). The developing roller 51Y is composed of a magnetic roller fixed inside and a sleeve that rotates around the magnetic roller. The first developer container 53Y and the second developer container 54Y contain two-component developer G consisting of carrier and toner. The second developer container 54Y is connected to the outlet 66 (see FIG. 3) of the toner supply device through an opening formed above it. The toner concentration detection sensor 56Y detects the toner concentration of the developer G in the second developer container 54Y.

[0026] The developer G in the developing device 50 is circulated between the first developer storage section 53Y and the second developer storage section 54Y while being agitated by two developer transport screws 55Y. The developer G in the first developer storage section 53Y is transported by one of the developer transport screws 55Y and supplied to and carried on the sleeve surface of the developing roller 51Y by the magnetic field generated by the magnet roller in the developing roller 51Y. The sleeve of the developing roller 51Y rotates counterclockwise as indicated by the arrow in FIG. 2, and the developer G carried on the developing roller 51Y moves along the developing roller 51Y as the sleeve rotates. At this time, the toner in the developer G is charged to a potential of opposite polarity to that of the carrier due to frictional charging with the carrier in the developer G and is electrostatically attracted to the carrier. The toner is then carried on the developing roller 51Y together with the carrier, which is attracted by the magnetic field generated on the developing roller 51Y.

[0027] The developer G carried on the developing roller 51Y is transported in the direction of the arrow in FIG. 2 and reaches the doctor section where the doctor blade 52Y and the developing roller 51Y face each other. The amount of developer G on the developing roller 51Y is adjusted as it passes through the doctor section, and then it is transported to the developing area, which is the position facing the photosensitive member 41Y. In the developing area, the toner in the developer G is attracted to the latent image formed on the photosensitive member 41Y by the developing electric field formed between the developing roller 51Y and the photosensitive member 41Y. The developer G remaining on the surface of the developing roller 51Y that has passed through the developing area reaches above the first developer container 53Y as the sleeve rotates, and is separated from the developing roller 51Y at this position.

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

[0029] The toner in each toner container 32 (Y, M, C, K) installed in the toner container storage unit 70 of the printer unit 100 is replenished into each developing device 50 (Y, M, C, K) as appropriate in accordance with the toner consumption in the developing device 50 (Y, M, C, K) of each color. At this time, the toner in each toner container 32 (Y, M, C, K) is replenished by a toner replenishing device 60 (Y, M, C, K) provided for each toner color.

[0030] Next, the toner supply devices 60 (Y, M, C, K) will be described. FIG. 3(a) is a perspective view showing a toner container 32 installed in a toner supply device 60, which is a powder conveying device, and FIG. 3(b) is a schematic diagram. The toner conveyance direction of the relay conveyance path 65 is normally perpendicular to the plane of FIG. 3(b). However, in FIG. 3(b), the toner conveyance direction of the relay conveyance path 65 is shown as the same direction as the conveyance nozzle 61 to make the configuration easier to understand. The four toner supply devices 60 (Y, M, C, K) and toner containers 32 (Y, M, C, K) have substantially the same structure except for the colors of toner used in the image creation process. Therefore, the color codes Y, M, C, and K will be omitted as appropriate in the following description.

[0031] The toner supply device 60 has a conveying nozzle 61 as a first conveying path, a vertical conveying path 64 as a connecting conveying path, and a relay conveying path 65 as a second conveying path. When the toner container 32 as a powder container is attached to the toner container storage unit 70 of the printer unit 100, the conveying nozzle 61 of the toner supply device 60 is inserted from the container tip side of the toner container 32 in conjunction with the attachment operation. This allows the inside of the toner container 32 and the inside of the conveying nozzle 61 to communicate with each other.

[0032] The toner container 32 is a substantially cylindrical toner bottle and is mainly composed of a container front cover 34 that is held non-rotatably in the toner container holder 70, and a container body 33 that is integrally formed with a container gear 301. The container body 33 is held rotatably relative to the container front cover 34.

[0033] The container body 33 is rotated by inputting a rotational drive force from the drive unit to a container gear provided on the container body 33. As the container body 33 rotates, the toner contained inside the container body 33 is transported toward the transport nozzle 61 along the longitudinal direction of the container body by the spiral protrusion 302 formed in a spiral shape on the inner peripheral surface of the container body 33.

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

[0035] A nozzle transport screw 164 serving as a first transport member is disposed within the transport nozzle 61, and when a rotational drive is input from a drive device to a first screw gear 98 fixed to the shaft portion of the transport nozzle 61, the nozzle transport screw 164 rotates and transports the toner supplied into the transport nozzle 61 in a horizontal direction. 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 down the vertical transport path 64 under its own weight and is transported to the relay transport path 65.

[0036] A relay conveying screw 165 is disposed within the relay conveying path 65 as a second conveying member, and when a rotational drive is input from the drive device to a second screw gear 96 fixed to the shaft portion of the relay conveying screw 165, the relay conveying screw 165 rotates and conveys the toner supplied into the relay conveying path 65 in a horizontal direction. A discharge port 66 is provided at the downstream end of the relay conveying path 65 in the conveying direction, and the toner conveyed by the relay conveying screw 165 falls from the discharge port 66 under its own weight and is replenished into the developing device 50.

[0037] The relay conveying path 65 is made of an elastic material such as elastomer rubber, and the relay conveying screw 165 is also made of an elastic material such as elastomer rubber, so that the relay conveying path 65 is configured to be elastically deformable.

[0038] The diameter of the relay conveying path 65 is shorter than the diameter of the conveying nozzle 61. Furthermore, the rotation speed of the nozzle conveying screw 164 is 189 rpm, and the rotation speed of the relay conveying screw 165 is 237 rpm, so that the rotation speed of the relay conveying screw 165 is faster than the rotation speed of the nozzle conveying screw 164. Note that the rotation speeds of each conveying screw are just examples, and may be set appropriately depending on the device configuration.

[0039] FIG. 4 is a cross-sectional view showing a part of the conveying nozzle 61 and the nozzle conveying screw 164, and the vertical conveying path 64. As shown in FIG. 3(b) and 4, a coil-shaped swinging member 166 is disposed within the vertical transport path 64. An eccentric portion 164c is provided at the connection portion of the nozzle transport screw 164 with the vertical transport path 64, and a hook portion 166a of the swinging member 166 is hooked onto this eccentric portion 164c. When the nozzle transport screw 164 rotates, the swinging member 166 moves up and down, thereby loosening the toner in the vertical transport path 64.

[0040] FIG. 5 is a schematic diagram of a conventional nozzle conveying screw 164. As shown in FIG. As shown in Fig. 5, the nozzle conveying screw 164 has a shaft portion 164a and an eccentric portion 164c. A main blade portion 164b and a reverse-winding blade portion 164e are spirally wound around the shaft portion 164a. The main blade portion 164b is located on the left side of the eccentric portion 164c in the figure, and conveys the toner taken in from the nozzle opening 62 toward the right side in the figure. The reverse-winding blade portion 164e is located on the left side of the eccentric portion 164c in the figure, and conveys the toner that does not fall into the vertical conveying path 64 toward the right side in the figure.

[0041] The eccentric portion 164c is eccentric in such a way that a portion of it is larger than the outer diameter of the shaft portion 164a and protrudes relative to the shaft portion 164a, thereby preventing a decrease in the rigidity of the nozzle conveying screw 164 and ensuring a sufficient amount of oscillation of the oscillating member 166.

[0042] In this way, because a part of the eccentric portion 164c is configured to protrude from the shaft portion 164a, there is a risk that the hook portion 166a of the swinging member 166 hooked onto the eccentric portion 164c may fall off the eccentric portion 164c during assembly, etc. For this reason, fall-off prevention portions 164d are provided on both ends of the eccentric portion 164c so as to protrude from the eccentric portion 164c. These fall-off prevention portions 164d are stepped portions that are one step higher outward than the shaft portion 164a.

[0043] Conventionally, this drop prevention portion 164d is provided around the entire circumference of the shaft. The end of the main blade portion 164b on the eccentric portion 164c side is connected to the drop prevention portion 164d. Therefore, as shown in FIG. 6(b), a wedge-shaped region A is formed downstream in the screw rotation direction from the end of the main blade portion 164b on the eccentric portion 164c side. That is, this region is such that the axial width between the downstream side surface of the main blade portion 164b in the rotation direction and the upstream end face of the drop prevention portion 164d in the toner transport direction narrows as the distance between the main blade portion 164b and the drop prevention portion 164d increases upstream in the screw rotation direction.

[0044] Toner transported to the wedge-shaped region A by the main blade portion 164b is blocked by the drop prevention portion 164d, which is a step raised from the shaft portion 164a, causing it to accumulate. As the nozzle transport screw 164 rotates, this accumulated toner moves to a location in the wedge-shaped region A where the gap between the main blade portion 164b and the drop prevention portion 164d becomes narrower. Pressure is applied to the accumulated toner in this region A, causing it to aggregate, as shown in Figure 6. If this aggregated toner eventually falls off and is replenished to the developing device, it may cause abnormal images such as white spots or white streaks. Furthermore, this aggregated toner may cause clogging, and in the worst case scenario, the aggregated toner may prevent the transport screw from rotating, potentially damaging the transport screw or the drive device that drives it.

[0045] In particular, as shown in FIG. 4, when the height of the toner inside the conveying nozzle is higher than the shaft portion 164a, toner aggregation is likely to occur in the wedge-shaped region A.

[0046] Therefore, in this embodiment, a step portion is formed in the circumferential direction in a location other than the location corresponding to the region A where aggregation may occur. Hereinafter, the characteristic features of this embodiment will be described as Example 1 with reference to the drawings.

[0047] [Example 1] FIG. 7 is a diagram showing the characteristic parts of the nozzle conveying screw of the first embodiment. FIG. 7 shows a configuration in which a portion of the drop-off prevention portion 164d is cut away, eliminating the drop-off prevention portion 164d in a region Z located a predetermined distance downstream from the main blade portion 164b in the rotation direction W of the nozzle transport screw, as indicated by the arrow in the figure. The configuration shown in FIG. 7 eliminates a step that would impede toner transport in region Z located a predetermined distance downstream from the end of the main blade portion 164b in the rotation direction W. This allows toner transported by the main blade portion 164b to move toward the eccentric portion 164c and fall into the vertical transport path 64 without accumulating. As a result, toner aggregation can be suppressed upstream of the drop-off prevention portion 164d in the toner transport direction. Furthermore, since the drop-off prevention portion 164d is provided in regions other than the region Z, the swinging member 166 hooked on the eccentric portion 164c can be effectively prevented from dropping off from the eccentric portion 164c.

[0048] The above-mentioned region Z may be determined appropriately depending on the region where pressure is applied to the toner by the step portion and the main blade portion 164b. For example, if the screw pitch of the main blade portion 164b is narrow and the inclination of the main blade portion 164b is steep, the narrow space between the main blade portion 164b and the step becomes longer in the circumferential direction. Therefore, the region where pressure is applied to the toner sandwiched between the step and the main blade portion 164b becomes longer in the circumferential direction. Therefore, in this case, the above-mentioned region Z is set to be longer in the circumferential direction compared to when the screw pitch of the main blade portion 164b is wide.

[0049] Furthermore, as long as the fall-off prevention portion 164d is provided over an angle of 180° or more in the circumferential direction, it is possible to prevent the swinging member 166 from falling off the eccentric portion 164c. Therefore, for example, a configuration may be adopted in which the fall-off prevention portion 164d is not provided in an area of ​​the main blade portion 164b that is a predetermined distance upstream in the rotation direction W of the nozzle conveying screw, and in which there is no step within a predetermined range on both sides of the rotation direction of the main blade portion 164b.

[0050] FIG. 8 shows another example of the configuration of the first embodiment. 8, the outer diameter of the shaft portion 164a is gradually increased from the downstream side in the rotation direction W of the nozzle conveying screw so that the outer diameter of the shaft portion corresponding to the wedge-shaped region A is the same as the outer diameter of the drop-off prevention portion 164d. Specifically, the outer diameter of a region α between the upstream end face of the drop-off prevention portion 164d of the shaft portion 164a in the toner conveying direction and the downstream side surface of the main blade portion 164b in the screw rotation direction gradually increases in the circumferential direction toward the portion corresponding to the wedge-shaped region A. With this configuration, it is possible to eliminate the step that hinders the transport of toner in region Z that is a predetermined distance from the end of main blade portion 164b in the rotational direction. As a result, the toner transported by main blade portion 164b moves to eccentric portion 164c without accumulating, and falls into vertical transport path 64. As a result, it is possible to prevent toner from coagulating before falling prevention portion 164d.

[0051] Fig. 9 is a diagram illustrating the circumferential position of region X of eccentric portion 164c that protrudes from shaft portion 164a. Fig. 9 is a cross-sectional view of main blade portion 164b at the downstream end position in the toner transport direction. Figs. 9(a) and 9(b) show a case where eccentric portion 164c does not have fall-off prevention portions 164d at both ends, while Figs. 9(c) and 9(d) show a case where eccentric portion 164c has fall-off prevention portions 164d at both ends. As shown in Figure 9(a), when region X protruding from shaft portion 164a of eccentric portion 164c overlaps with region Z located a predetermined distance downstream in the rotation direction W from the end of main blade portion 164b, the above-mentioned wedge-shaped region A is formed by the step portion of the part of eccentric portion 164c protruding from shaft portion 164a and main blade portion 164b.

[0052] Furthermore, as shown in FIG. 9(c), even if the fall-off prevention portion 164d is notched and the fall-off prevention portion 164d is not provided in the region Z, if the region X protruding from the shaft portion 164a of the eccentric portion 164c overlaps with the region Z located a predetermined distance downstream in the rotation direction W from the end of the main blade portion 164b, the step portion of the part of the eccentric portion 164c protruding from the shaft portion 164a and the main blade portion 164b will form the wedge-shaped region A.

[0053] In this way, if the region X protruding from the shaft portion 164a of the eccentric portion 164c overlaps with the region Z located a predetermined distance in the rotational direction from the end of the main blade portion 164b, the above-mentioned wedge-shaped region A is formed, and as described above, there is a risk of toner aggregation occurring.

[0054] 9(b) and 9(d), eccentric portion 164c is configured so that region X protruding from shaft portion 164a of eccentric portion 164c in the circumferential direction does not enter region Z located a predetermined distance downstream in the rotation direction W from the end of main blade portion 164b. This prevents the formation of the wedge-shaped region A described above by the blade portion and the step portion formed by region X protruding from shaft portion 164a of eccentric portion 164c. As a result, toner transported by main blade portion 164b moves to eccentric portion 164c without accumulating and falls into vertical transport path 64. As a result, toner aggregation can be suppressed before falling-off prevention portion 164d.

[0055] Next, another method for suppressing toner aggregation at the upstream end of the falling-off prevention portion 164d in the toner transport direction will be described as a second embodiment.

[0056] [Example 2] FIG. 10 is a diagram showing the characteristic parts of the nozzle conveying screw of the second embodiment. As shown in FIG. 10 , in the second embodiment, a predetermined gap d is provided in the axial direction between the downstream end 164b1 of the main blade 164b in the toner transport direction and the step formed by the drop-off prevention portion 164d. The gap d between the downstream end 164b1 of the main blade 164b in the toner transport direction and the step formed by the drop-off prevention portion 164d is preferably 2 mm or more. Furthermore, if the downstream end 164b1 of the main blade 164b in the toner transport direction is located in the vertical transport path 64, the main blade 164b can efficiently transport toner to the vertical transport path 64. Therefore, the axial length from the end of the eccentric portion 164c on the main blade side to the sidewall of the vertical transport path 64 on the main blade 164b side is configured to be 2 mm or more. This ensures that the gap d is 2 mm or more, and the main blade 164b can efficiently transport toner to the vertical transport path 64.

[0057] In this second embodiment, a gap for letting toner escape is formed on the upstream side of the screw rotation direction in wedge-shaped region A where the gap between main blade portion 164b and drop-off prevention portion 164d narrows. As a result, toner that has been impeded in its transport by the step portion of drop-off prevention portion 164d and remains there escapes through gap d between downstream end portion 164b1 of main blade portion 164b in the toner transport direction and the step portion of drop-off prevention portion 164d. This makes it possible to prevent an increase in pressure on the toner in wedge-shaped region A and to prevent toner aggregation in wedge-shaped region A.

[0058] Note that the amount of toner transported by the reverse-wound blade portion 164e to the eccentric portion 164c is small. Therefore, the height of the toner in the area of ​​the reverse-wound blade portion 164e is equal to or lower than the shaft portion 164a. Therefore, the toner transported by the reverse-wound blade portion 164e is rarely blocked by the step of the fall-off prevention portion. Therefore, toner aggregation is unlikely to occur in the wedge-shaped area formed by the step between the reverse-wound blade portion 164e and the fall-off prevention portion 164d. Therefore, in this embodiment, the configurations of Examples 1 and 2 are not adopted in the area of ​​the reverse-wound blade portion 164e. However, if there is a risk of toner aggregation occurring in the wedge-shaped area formed by the step between the reverse-wound blade portion 164e and the fall-off prevention portion 164d, the configurations of Examples 1 and 2 described above may be applied as appropriate.

[0059] In the above-described embodiment, an example of applying the present invention to a toner supply device that transports toner in a toner container to a developing device has been described, but the present invention can also be applied to, for example, a waste toner transport device that transports waste toner removed by a cleaning device to a waste toner tank.

[0060] The above description is merely an example, and each of the following aspects provides unique effects. (Aspect 1) In a conveying screw such as a nozzle conveying screw 164, which has a shaft portion 164a and a blade portion such as a main blade portion 164b spirally wound around the shaft portion 164a and conveys powder such as toner toward one end of the blade portion, a step portion such as a fall prevention portion 164d is provided at the axial position of one end, such as the downstream end in the toner conveying direction, of the blade portion, which is one step higher from the outer surface of the shaft portion 164a in a direction away from the center of the shaft portion 164a, and the step portion is formed outside of a region Z in the circumferential direction from one end of the blade portion to a position a predetermined distance downstream in the rotational direction of the conveying screw. When a step portion is formed in the region from one end of a blade portion such as the main blade portion 164b to a predetermined position downstream in the direction of rotation of the conveying screw (region Z shown in FIG. 7B) that is one step higher from the outer peripheral surface of the shaft portion 164a in a direction away from the center of the shaft portion 164a, the space formed by the upstream end face of the step portion in the conveying direction and the downstream side face of the blade in the conveying direction becomes the following space: That is, it is a wedge-shaped space (wedge-shaped region A shown in FIG. 5) in which the axial width between the end face of the step portion and the side face of the blade gradually narrows from the upstream side in the direction of rotation of the conveying screw toward the connection point between the blade portion and the step portion. Powder such as toner that moves into the wedge-shaped space as the conveying screw rotates is hindered from moving axially by the step portion and becomes stagnant in this wedge-shaped space. As the conveying screw rotates, the powder remaining in the wedge-shaped space enters the narrower axial width portion between the end face of the stepped portion of the wedge-shaped space and the side face of the blade, and is subjected to pressure, which can result in a problem of the powder agglomerating in the wedge-shaped space. On the other hand, in the first aspect, no step is formed in the region Z extending from one end of the blade to a position a predetermined distance downstream in the rotation direction of the conveying screw, and therefore no wedge-shaped space is formed, thereby preventing the powder from agglomerating.

[0061] (Aspect 2) In aspect 1, the blade portion such as the main blade portion 164b has an eccentric portion 164c at one end, which is the downstream end in the toner transport direction, that protrudes partially from the outer circumferential surface of the shaft portion 164a and is eccentric, and the circumferential position of the region from the one end of the blade portion to a position a predetermined distance downstream in the rotation direction of the transport screw is made different from the circumferential position of the region X of the eccentric portion 164c that protrudes from the outer circumferential surface of the shaft portion 164a. 9, the portion of eccentric portion 164c that protrudes from the outer peripheral surface of shaft portion 164a forms a step that is one step higher than the outer peripheral surface of shaft portion 164a in a direction away from the center of shaft portion 164a. Therefore, when region X that protrudes from the outer peripheral surface of the shaft portion of eccentric portion 164c overlaps with region Z that extends from one end of a blade portion such as main blade portion 164b to a position a predetermined distance downstream in the rotation direction of the conveying screw, a wedge-shaped region A is formed by the step formed by the portion of eccentric portion 164c that protrudes from the outer peripheral surface of the shaft portion and the blade portion. As a result, there is a risk of powder aggregation occurring in this wedge-shaped region A. In contrast, in the second aspect, the circumferential positions of the region Z extending from one end of the blade portion to a position a predetermined distance downstream in the rotation direction of the conveying screw and the region X of the eccentric portion 164c protruding from the outer circumferential surface of the shaft portion 164a are different from each other, so that no step is formed in the region Z. As a result, the wedge-shaped region A is not formed, and the powder can be conveyed by the blade portion without toner stagnation. As a result, the aggregation of the powder can be suppressed.

[0062] (Aspect 3) In aspect 2, both axial ends of the eccentric portion 164c are provided with anti-fall portions 164d that protrude from the eccentric portion 164c and prevent the oscillating member 166, which protrudes from the eccentric portion 164c and is hooked onto the eccentric portion 164c, from falling off from the eccentric portion 164c, and the anti-fall portions 164d formed on the end portions of the eccentric portion 164c on the blade portion side, such as the main blade portion 164b, are formed outside the region Z in the circumferential direction, up to a position a predetermined distance downstream from the blade portion in the rotational direction of the conveying screw. 7, the fall-off prevention portion 164d is a step that rises one step from the outer circumferential surface of the shaft portion 164a in the direction away from the center of the shaft portion 164a. Therefore, if the fall-off prevention portion 164d is formed in a region Z from one end of a blade portion, such as the main blade portion 164b, downstream in the toner transport direction to a predetermined position downstream in the rotation direction of the transport screw, a wedge-shaped region A is formed by the step formed by the fall-off prevention portion 164d and the blade portion. As a result, there is a risk that powder will aggregate in this wedge-shaped region A. In contrast, in aspect 3, the drop prevention portion 164d formed at the blade end, such as the downstream end of the eccentric portion 164c in the toner transport direction, is formed outside of region Z, which extends from one end of the blade to a position a predetermined distance downstream in the rotation direction of the transport screw. As a result, there is no step portion due to the drop prevention portion 164d in region Z, and the above-mentioned wedge-shaped region A is not formed. Therefore, the toner does not accumulate, and the powder can be transported by the blade. As a result, the occurrence of powder aggregation can be suppressed.

[0063] (Aspect 4) In aspect 1, the outer diameter dimension of the shaft portion 164a between the side surface of the blade portion such as the main blade portion 164b downstream in the rotation direction of the conveying screw and the end face of the step portion upstream in the powder conveying direction, from one end of the blade portion to a position a predetermined distance downstream in the rotation direction of the conveying screw, is gradually increased in the circumferential direction so that the outer diameter dimension of the shaft portion is the same as the outer diameter dimension of the step portion. 8, there is no step in the region Z from the blade portion to a position a predetermined distance downstream in the rotation direction of the conveying screw, and the wedge-shaped region A described above is not formed. This allows the blade portion to convey the stepped powder without the toner accumulating. As a result, the occurrence of powder aggregation can be suppressed.

[0064] (Aspect 5) The conveying screw has a shaft portion 164a and a blade portion such as a main blade portion 164b spirally wound around the shaft portion 164a, and conveys powder toward one end of the blade portion.The conveying screw has a step portion that is one step higher from the outer surface of the shaft portion 164a in a direction away from the center of the shaft portion 164a, and has a predetermined gap d between one end of the blade portion and the step portion. As explained using Figure 10, this allows powder whose transport is hindered by the step portion to pass through the gap d between the blade portion and the step portion, thereby preventing the powder from accumulating downstream in the direction of rotation of one end of the blade portion, and preventing toner from agglomerating downstream in the direction of rotation of one end of the blade portion.

[0065] (Aspect 6) In a powder conveying device such as a toner supply device 60 having a conveying screw such as a nozzle conveying screw 164 inside and a conveying path such as a conveying nozzle 61 for conveying powder, As the conveying screw, any one of the conveying screws according to embodiments 1 to 5 was used. This can prevent the powder from agglomerating in the transport path.

[0066] (Aspect 7) In the sixth embodiment, the powder height in the conveying path of the conveying nozzle 61 and the like is higher than the shaft portion 164a of the conveying screw. This makes it possible to prevent the powder from agglomerating in the transport path, as described in the embodiment.

[0067] (Aspect 8) In an image forming apparatus equipped with an image forming means such as an image forming unit 46 that forms a toner image and a toner conveying device such as a toner supply device that conveys toner, the powder conveying device of any of aspects 1 to 7 was used as the toner conveying device. This makes it possible to suppress the aggregation of toner. [Explanation of symbols]

[0068] 32: Toner container 33: Container body 34: Container tip cover 46: Imaging section 50: Developing device 60: Toner supply device 61: Conveying nozzle 62: Nozzle opening 64: Vertical conveyor 65: Relay transport route 66: Outlet 70: Toner container storage section 100: Printer section 164: Nozzle conveying screw 164a:Shaft part 164b: Main blade 164b1: downstream end in the toner transport direction 164c: Eccentric part 164d: Falling prevention part 164e: Reverse winding blade 165: Relay transport screw 166: Swinging member 166a: Hook part 301: Container gear 302 : Spiral projection 400: Scanner section A: Wedge-shaped area Z: Area from the main blade to a specified distance downstream in the direction of rotation d: Axial gap between the downstream end of the main blade in the toner transport direction and the step [Prior art documents] [Patent documents]

[0069] [Patent Document 1] Japanese Patent Application Publication No. 2019-159129

Claims

1. A shaft portion; a blade portion spirally wound around the shaft portion, A conveying screw that conveys powder toward one end of the blade portion, an eccentric portion at one end of the blade portion, the eccentric portion being partially protruding from the outer circumferential surface of the shaft portion; a fall prevention portion provided at each axial end of the eccentric portion to prevent the swinging member, which protrudes from the eccentric portion and is hooked onto the eccentric portion, from falling off from the eccentric portion; The fall-off prevention portion is provided around the shaft portion, One end of the blade portion is connected to the fall-off prevention portion, A conveying screw characterized in that the outer diameter dimension of the shaft portion outside the region between the downstream side of the blade portion in the rotation direction of the conveying screw and the upstream end face of the anti-fall portion formed at the end of the eccentric portion on the blade portion side, from one end of the blade portion to a position a predetermined distance downstream in the rotation direction of the conveying screw, is gradually increased from the downstream side in the rotation direction of the conveying screw so that the outer diameter dimension of the region is the same as the outer diameter dimension of the anti-fall portion.

2. The conveying screw according to claim 1, A conveying screw characterized in that the circumferential position of the area from one end of the blade portion to a position a predetermined distance downstream in the rotation direction of the conveying screw is different from the circumferential position of the area of ​​the eccentric portion that protrudes from the outer peripheral surface of the shaft portion.

3. A powder conveying device having a conveying screw therein and a conveying path for conveying powder, A powder conveying device, characterized in that the conveying screw according to claim 1 or 2 is used as the conveying screw.

4. 4. The powder conveying device according to claim 3, the transport path is a horizontal transport path that transports the powder in a horizontal direction, A powder conveying device characterized in that the height of the powder in the horizontal conveying path is higher than the lower end of the shaft portion of the conveying screw.

5. an imaging means for forming a toner image; an image forming apparatus including a toner transport device that transports toner, 5. An image forming apparatus, comprising the powder transport device according to claim 3 or 4 as the toner transport device.

Images