JP5820940B2 - Toner conveying apparatus and image forming apparatus having the same - Google Patents

Description

  The present invention relates to a toner conveying device used in an image forming apparatus such as a copying machine, a printer, a facsimile machine, or a multifunction machine thereof.

  In a conventional image forming apparatus, a powder developer is mainly used, and an electrostatic latent image formed on an image carrier such as a photosensitive drum is visualized by using the developing apparatus, and the visible image (toner) In general, a process of fixing an image) onto a recording medium and then performing a fixing process. The toner remaining on the surface of the image carrier is removed by a cleaning device, and a new toner image is formed. The residual toner removed by the cleaning device is stored in a waste toner bottle. When the waste toner bottle becomes full after printing a predetermined number of sheets, the user is notified and the waste toner bottle is discarded or replaced.

  As a waste toner collecting path from the cleaning device to the waste toner bottle, a toner transport path having a transport screw in a pipe-shaped transport path is known. In such a toner conveyance path, when the outer peripheral track during rotation of the conveyance screw becomes larger than the inner diameter of the conveyance path due to dimensional tolerance of the outer diameter of the conveyance screw and the inner diameter of the conveyance path, warpage of the conveyance screw, or the like, There is a possibility that an excessive rotational load is generated due to friction and the conveying screw does not rotate. Therefore, the dimensions are usually set so that the outer diameter of the conveying screw is smaller than the inner diameter of the conveying path.

  However, when such a dimension setting is performed, there is a clearance (gap) between the conveying screw and the conveying path, so that if the conveying screw is warped, the conveying screw is swung in the radial direction (eccentric. Rotating, hitting the inner surface of the transport path and hitting sound.

  More specifically, when the conveying screw is warped, when the warping is downward, the bending due to the weight of the conveying screw is added in the same direction as the warping, and the amount of deformation increases. On the other hand, when the warp is upward, the deformation due to the weight of the conveying screw acts in the opposite direction to the warp. For this reason, when the conveying screw rotates from a state in which the warping is upward, since the deformation due to the weight of the conveying screw gradually acts in the direction of increasing the warping from the state where the deformation amount is small and balanced, the conveying screw becomes large. It rotates while deforming so as to wave, and collides with the inner surface of the conveyance path. At this time, the generated striking sound increases as the warp increases, and the clearance (gap) between the conveying screw and the inner surface of the conveying path increases, and increases as the weight of the conveying screw increases.

  Therefore, Patent Document 1 provides a portion in which the outer diameter of the spiral protrusion (spiral wing) of the conveying screw is very close to the inner diameter of the cylindrical conveying path, and a part of the outer diameter of the conveying screw is cylindrically conveyed. A toner conveying device is disclosed that is capable of stably rotating while being in contact with the inside of a path.

  Patent Document 2 includes a pipe body having a semi-tubular portion and a semi-tubular lid joined to the semi-tubular portion. The joining surface of the pipe body and the semi-tubular lid is substantially flat, and is joined. A toner conveying pipe excellent in airtightness and dimensional accuracy with ultrasonic welding of the part is disclosed.

JP 2002-132109 A JP 2005-91809 A

  However, in the methods of Patent Documents 1 and 2, there is a limit in setting the clearance between the conveying screw and the cylindrical conveying path due to dimensional tolerances and assembly tolerances of the parts, and if the warp generated in the conveying screw exceeds the clearance, the conveying path The impact sound could not be prevented reliably. Moreover, in patent document 1, since the outer diameter of the spiral wing and the inner diameter of the cylindrical transport path are made close to each other over almost one turn of the spiral wing of the transport screw, almost one turn of the spiral wing is transported by the transport path. When the rotational load is further increased due to the presence of toner in the clearance between the conveying screw and the conveying path, the fluidity of the toner is reduced due to frictional heat, resulting in poor conveying efficiency. If left as it is for a long time, the toner may solidify.

  In the above, a problem has been described in the case where the toner conveying path having the conveying screw in the pipe-shaped conveying path is used as the waste toner collecting path from the cleaning device to the waste toner bottle. However, in order to supply toner to the developing device. In the toner replenishment path used when replenishing toner from the toner cartridge to the developing device according to the consumption of toner in the developing device, a toner conveying path having a conveying screw in the conveying pipe is also provided. Similar problems arise when used.

  SUMMARY OF THE INVENTION In view of the above problems, the present invention includes a toner conveying device that can prevent the generation of a striking sound due to a collision between the conveying screw and the inner surface of the conveying path and can maintain stable toner conveying performance over a long period of time. An object is to provide an image forming apparatus.

  In order to achieve the above object, the present invention has a circular cross section in which a conveying screw having a rotating shaft and a conveying blade formed on the outer peripheral surface of the rotating shaft, and the conveying screw is rotatably arranged inside. In the toner conveying device comprising a toner conveying pipe, the conveying blade includes a rib whose outer peripheral edge viewed from the axial direction of the rotating shaft is arcuate about the axis of the rotating shaft. The distance from the axis of the rotating shaft to the outer peripheral edge of each rib is equal to the radius of the inner peripheral surface of the toner conveying pipe, or the inner peripheral The ribs are slightly smaller than the radius of the surface, and each of the ribs is formed in a range of 180 ° or less within a range of ½ circumference or less of the conveying wing, and is viewed from the axial direction of the rotating shaft. 180 ° when combined with each rib The formation range of the ribs in the longitudinal direction of the conveying screw is approximately the center portion in the longitudinal direction of the conveying screw and is within a range of 1/3 of the total length of the conveying screw.

  According to the present invention, in the toner conveying device having the above-described configuration, each of the ribs is formed so as to be evenly assigned to the outer peripheral edge of the conveying blade as viewed from the axial direction of the rotating shaft.

  The present invention also provides an image forming apparatus on which the toner conveying device having the above-described configuration is mounted.

  According to the first configuration of the present invention, the conveying screw is configured so that the rotating shaft is substantially linear by the plurality of ribs formed on the outer peripheral surface of the conveying blade in a range exceeding 180 ° when viewed from the axial direction of the rotating shaft. Therefore, the deformation of the conveying screw due to the interaction between the warp of the conveying screw and the bending due to its own weight is suppressed. Therefore, it is possible to effectively suppress the generation of a striking sound due to a collision between the conveying screw and the inner surface of the toner conveying pipe. In addition, each rib is formed at an interval of 1 pitch or more of the conveying wings, and is formed by shifting the phase within a range of 180 ° or less within a range of ½ or less of the conveying wings. The load applied in the radial direction can be released. Therefore, there is no possibility that the rotational load of the conveying screw increases due to the contact between the rib and the inner wall surface of the toner conveying pipe, or the conveying screw cannot be rotated. Further, by forming a rib in a range within 1/3 of the entire length of the conveying screw at the substantially central portion in the longitudinal direction of the conveying screw where the conveying screw is likely to warp, an effect of smoothly rotating the conveying screw is obtained. Ribs can be formed in the minimum necessary range.

  Further, according to the second configuration of the present invention, in the toner conveyance device of the first configuration, each rib is formed so as to be evenly allocated to the outer peripheral edge of the conveyance blade as viewed from the axial direction of the rotation shaft. As a result, the conveying screw has a uniform rotation in the radial direction and a small amount of uneven rotation.

  In addition, according to the third configuration of the present invention, the mounting of the toner conveying device of the first or second configuration generates a striking sound due to a collision between the conveying screw and the inner surface of the toner conveying pipe, and the toner. An image forming apparatus excellent in quietness and maintainability that can effectively prevent a decrease in the fluidity and solidification of toner in the transport pipe.

1 is a schematic cross-sectional view showing an overall configuration of an image forming apparatus 1 including a toner conveying device 30 of the present invention. Side surface sectional drawing which shows the structure of the toner conveying apparatus 30 which concerns on one Embodiment of this invention, and the cleaning apparatus 7 vicinity connected with this. The perspective view which shows the state which cut | disconnected the toner conveyance pipe 31 which comprises the toner conveyance apparatus 30 of this invention in the approximate center part of the longitudinal direction. An enlarged perspective view of a conveying screw 35 used in the toner conveying device 30 of the present invention. The front view which looked at the cross section which cut the toner conveyance pipe 31 in the position corresponding to the rib 40a from the axial direction of the conveyance screw 35 The front view which looked at the cross section which cut the toner conveyance pipe 31 in the position corresponding to the rib 40b from the axial direction of the conveyance screw 35 The front view which looked at the cross section which cut the toner conveyance pipe 31 in the position corresponding to the rib 40c from the axial direction of the conveyance screw 35 The front view which looked at the cross section which cut the toner conveyance pipe 31 in the position corresponding to the rib 40d from the axial direction of the conveyance screw 35 The cross section of the conveying screw 35 and the toner conveying pipe 31 in which the ribs 40a to 40c are formed in the range of about 1/3 round (120 °) of the conveying blade 35a is cut at a position corresponding to the rib 40a. View from the front The cross section of the conveying screw 35 and the toner conveying pipe 31 in which the ribs 40a and 40b are formed in the range of about ½ circumference (180 °) of the conveying blade 35a is cut at a position corresponding to the rib 40a. View from the front

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing a configuration of an image forming apparatus 1 of the present invention. In an image forming apparatus (for example, a monochrome printer) 1, when performing an image forming operation, the photosensitive drum 3 that rotates clockwise in FIG. 1 is uniformly charged by the charging unit 2, and an exposure unit (laser) based on the image data. An electrostatic latent image is formed on the photosensitive drum 3 by a laser beam from the scanning unit 4), and a developer (hereinafter referred to as toner) is attached to the electrostatic latent image by the developing unit 5 to form a toner image. The

  The toner is supplied to the developing unit 5 from the toner container 6. The image data is transmitted from a personal computer (not shown) or the like. Further, a static elimination device (not shown) for removing residual charges on the surface of the photosensitive drum 3 is provided on the downstream side of the cleaning device 7 with respect to the rotation direction of the photosensitive drum 3.

  A sheet (transfer paper, OHP, or the like) is conveyed from the sheet feeding cassette 8 via the sheet conveyance path 9 toward the photosensitive drum 3 on which the toner image is formed as described above, and is transferred by the registration roller pair 10. 11 (image transfer unit) is adjusted for feeding timing. Then, the toner image formed on the surface of the photosensitive drum 3 is transferred to the sheet by the transfer roller 11. The sheet onto which the toner image has been transferred is separated from the photosensitive drum 3 and conveyed to a fixing unit 13 having a fixing roller pair 12 to fix the toner image. The sheet that has passed through the fixing unit 13 is conveyed to the upper part of the apparatus by the sheet conveying path 14 and is discharged from the discharge roller pair 15 to the discharge tray 16.

  On the other hand, the toner remaining on the surface of the photosensitive drum 3 is removed by the cleaning device 7. The photosensitive drum 3 is neutralized by a neutralizing device (not shown) and then charged again by the charging unit 2, and thereafter image formation is performed in the same manner.

  The photosensitive drum 3 is formed by laminating a photosensitive layer made of amorphous silicon (a-Si) or an organic photosensitive layer (OPC) on an outer peripheral surface of an aluminum drum, for example, so that the surface is charged by the charging unit 2. It has become. Then, an electrostatic latent image in which charging is attenuated is formed on the surface that has received the laser beam from the exposure unit 4. The charging unit 2 charges the surface of the photosensitive drum 3 by discharging (for example, corona discharge). For example, the charging unit 2 is discharged by applying a high voltage using a thin wire or the like as an electrode. .

  The exposure unit 4 irradiates the photosensitive drum 3 with a light beam (for example, a laser beam) based on the image data, and forms an electrostatic latent image on the surface of the photosensitive drum 3. The developing unit 5 includes a developing roller disposed so as to face the photosensitive drum 3, and a developer contained therein is attached to the electrostatic latent image on the photosensitive drum 3 by the developing roller to form a toner image.

  The cleaning device 7 removes the toner (residual toner) remaining on the surface of the photosensitive drum 3 after the toner image is transferred to the sheet. The detailed configuration of the cleaning device 7 will be described later.

  In the fixing unit 13, a fixing roller pair 12 including a heating roller rotating in a clockwise direction in FIG. 1 and a pressure roller rotating in a counterclockwise direction in FIG. ing. The sheet on which the toner image is transferred by the transfer roller 11 is carried into the fixing unit 13 and passes through the fixing nip portion of the fixing roller pair 12. At this time, the toner image on the sheet is melted and fixed to be a permanent image by being heated and pressurized at a predetermined temperature and pressure.

  FIG. 2 is a cross-sectional view of a principal part showing a configuration in the vicinity of the cleaning device 7 including the toner conveying device 30 of the present invention. The housing 7 a of the cleaning device 7 includes a rubbing roller 21, a cleaning blade 22, and a recovery screw 23 that are in line contact with the longitudinal direction of the photosensitive drum 3 by a spring (not shown).

  The rubbing roller 21 is pressed against the photosensitive drum 3 with a predetermined pressure, and is rotated (forward rotation) in the same direction on the contact surface with the photosensitive drum 3 by a driving means (not shown). It is controlled to be faster than the peripheral speed of the body drum 3 (1.2 times here). Examples of the rubbing roller 21 include a structure in which a foam layer made of EPDM rubber and having an Asuka C hardness of 55 ° is formed as a roller body around a metal shaft. The material of the roller body is not limited to EPDM rubber, but may be a rubber or foamed rubber body of another material, and those having an Asuka C hardness of 10 to 90 ° are preferably used.

  A cleaning blade 22 is fixed in contact with the photosensitive drum 3 on the surface of the photosensitive drum 3 downstream of the contact surface with the rubbing roller 21 in the rotation direction. As the cleaning blade 22, for example, a polyurethane rubber blade having a JIS hardness of 78 ° is used, and is attached at a predetermined angle with respect to the tangential direction of the photosensitive drum 3 at the contact point. The material, hardness, dimensions, the amount of biting into the photosensitive drum 3 and the pressure contact force of the cleaning blade 22 are appropriately set according to the specifications of the photosensitive drum 3.

  The residual toner scraped off from the surface of the photosensitive drum 3 by the rubbing roller 21 or the cleaning blade 22 falls due to gravity and gradually accumulates in the housing 7a. Then, as the recovery screw 23 rotates, the toner in the housing 7a is sequentially conveyed in the longitudinal direction of the housing 7a (direction perpendicular to the paper surface of FIG. 2), and a toner discharge portion provided at one end of the bottom surface of the housing 7a. 25 is discharged to the outside of the cleaning device 7.

  The toner conveying device 30 includes a toner conveying pipe 31 and a conveying screw 33. A toner carry-in port 32 and a toner discharge port 33 are formed at both ends of the toner transport pipe 31. The toner carry-in port 32 is connected to the toner discharge unit 25 of the cleaning device 7, and the toner discharge port 33 is connected to a waste toner bottle 37. Has been. The conveying screw 35 includes a conveying blade (spiral blade) 35a and a rotating shaft 35b penetrating through the center thereof, and is rotatably supported in the toner conveying pipe 31. One end of the rotating shaft 35b extends to the outside of the toner conveying pipe 31, and a drive input gear 39 is attached to the tip of the rotating shaft 35b. The drive input gear 39 is connected to a drive motor (not shown), and the conveying screw 35 is rotationally driven at a predetermined speed. As the conveying screw 35 rotates in the direction of arrow A in the drawing, the toner carried into the toner conveying pipe 31 from the cleaning device 7 via the toner inlet 32 is sequentially conveyed in the toner conveying pipe 31 in the direction of arrow B. The toner is stored in the waste toner bottle 37 through the toner discharge port 33.

  FIG. 3 is a perspective view showing a state in which a toner transport pipe 31 used in the toner transport device 30 of the present invention is cut at a substantially central portion in the longitudinal direction, and FIG. 4 is a transport screw used in the toner transport device 30 of the present invention. FIG. As shown in FIG. 3, the toner conveying pipe 31 is formed in a cylindrical shape by combining an upper pipe 31a and a lower pipe 31b having a semicircular cross section. As shown in FIG. 4, the conveying screw 35 is integrally formed with ribs 40a, 40b, 40c, and 40d on the outer peripheral edge of the conveying blade 35a. In FIG. 4, the rib 40d is not shown.

  The outer peripheral edges of the ribs 40a to 40d have an arc shape centered on the axis O (see FIG. 5) of the rotation shaft 35b when viewed from the axial direction of the rotation shaft 35b. The distance from the axis O to the outer peripheral edge of the ribs 40a to 40d is formed to be equal to or slightly smaller than the radius of the inner peripheral surface of the toner transport pipe 31. Each of the ribs 40a to 40d is formed in a range of about ¼ circumference (90 °) of the conveying blade 35a, and is formed by shifting the phase by 90 ° for every two pitches of the conveying blade 35a.

  5 to 8 are front views of the cross section of the toner transport pipe 31 as viewed from the axial direction of the transport screw 35, and show cross sections at positions corresponding to the ribs 40a to 40d, respectively. 5 to 8, the perpendicular direction extending from the axis O to the upper pipe 31a is 0 °, and the angle increases in the clockwise direction. In FIG. 5, the rib 40a is in contact with or close to the inner wall surface of the toner transport pipe 31 in the range of about 0 ° to 90 °, and the transport screw 35 moves in the direction in which the rib 40a is formed (upper right direction in FIG. 5). Is regulated.

  Similarly, in FIGS. 6 to 8, the ribs 40 b to 40 d are in contact with or close to the inner wall surface of the toner transport pipe 31 in the ranges of about 90 ° to 180 °, about 180 ° to 270 °, and about 270 ° to 360 °, respectively. The transport screw 35 is restricted from moving in the direction in which the ribs 40b to 40d are formed. That is, the conveyance screw 35 is restricted from moving in the radial direction over the entire circumference (360 °) of the rotation shaft 35 b, and the axis O of the rotation shaft 35 b substantially coincides with the central axis of the toner conveyance pipe 31. ing.

  With this configuration, when the conveying screw 35 is warped, the direction of the warping exceeds the uppermost point with the rotation of the conveying screw 35, and even if an attempt is made to swing in the direction in which the warping is increased by the deflection of its own weight (radially outward), Since the ribs 40a to 40d formed on the outer peripheral edge of the conveying blade 35a are in contact with the inner wall surface of the toner conveying pipe 31, a wavy deformation in the radial direction of the conveying screw 35 due to the interaction between the warp and the deflection due to its own weight. It is suppressed. Accordingly, the conveying screw 35 rotates with the ribs 40a to 40d being supported so that the rotation shaft 35b is substantially in a straight line, and the generation of impact sound due to the collision between the conveying screw 35 and the inner surface of the toner conveying pipe 31 is also effective. Can be suppressed.

  Here, the ribs 40a to 40d are formed so as to be shifted in phase by 90 ° every two pitches of the conveying blade 35a. Therefore, when viewed from the entire conveying screw 35, the ribs 40a to 40d move in the radial direction around the entire circumference of the rotation shaft 35b. However, when viewed in the range of one pitch of the conveying blade 35a, only one direction (90 ° range) around the rotation shaft 35b is restricted, and predetermined in the other direction (270 ° range). The clearance C is ensured.

  Since the clearance C is set to such an extent that the dimensional tolerance and assembly tolerance of the toner conveyance pipe 31 and the conveyance screw 35 can be absorbed, the conveyance screw 35 can release the load applied in the radial direction due to the bending of the rotating shaft 35b. . Therefore, there is no possibility that the rotational load of the conveying screw 35 increases due to the contact between the ribs 40a to 40d and the inner wall surface of the toner conveying pipe 31, or the conveying screw 35 cannot be rotated.

  Accordingly, since the rotation load of the conveying screw 35 smoothly rotates without increasing, the generation of frictional heat due to the rotation of the conveying screw 35 can be suppressed, and the fluidity of the toner in the toner conveying pipe 31 is reduced. And solidification can be effectively suppressed. Moreover, the load of the drive motor that rotates the conveying screw 35 can also be reduced.

  Further, by assigning the ribs 40a to 40d evenly to the outer peripheral edge of the conveying blade 35a when viewed from the axial direction of the rotating shaft 35b, the conveying screw 35 having a uniform radial balance and less rotation unevenness can be obtained. Furthermore, when the formation ranges of the respective ribs 40a to 40d are matched, it is possible to surely prevent the conveying screw 35 from rattling in the radial direction by setting it to one turn (360 °) or more of the conveying blade 35a. it can.

  At this time, as shown in FIGS. 5 to 8, the end portions of the ribs 40 a to 40 d viewed from the axial direction of the rotating shaft 35 b are formed so as to overlap each other, and the rib 40 a when viewed from the axial direction of the rotating shaft 35 b. By keeping the clearance of ˜40d, the ends of the ribs 40a to 40d are not easily caught at the joint between the upper pipe 31a and the lower pipe 31b, and the rotation of the conveying screw 35 becomes smooth.

  In the present embodiment, the ribs 40a to 40d are formed in the range of about ¼ circumference (90 °) of the conveying blade 35a, and the phases of the ribs 40a to 40d are shifted by 90 °, but this is not limitative. The ribs can be formed in a range of ½ circumference (180 °) or less of the conveying blade 35a, and the phase of each rib can be shifted by an arbitrary angle within 180 °. Then, when the formation ranges of the ribs viewed from the axial direction of the rotating shaft 35b are combined to exceed 180 °, the rotational load of the conveying screw 35 is controlled while restricting the movement of the conveying screw 35 in the radial direction. The rise can also be suppressed.

  For example, as shown in FIG. 9, ribs 40a are formed in a range of about 1/3 round (120 °) of the conveyance blade 35a, and the phases of the ribs 40b, 40c are shifted by 120 ° every two pitches of the conveyance blade 35a. (Indicated by a broken line) may be formed. Also, as shown in FIG. 10, ribs 40a are formed in the range of about ½ circumference (180 °) of the conveying blades 35a, and the phase of the conveying blades 35a separated by two pitches is shifted by 180 °, and the ribs 40b (in broken lines). Display) may be formed.

  Further, the axial interval for forming each rib is not limited to every two pitches of the conveying blades 35a, but may be formed every one pitch of the conveying blades 35a, or may be formed every three pitches.

  Further, in the present embodiment, the ribs 40a to 40d are formed only at substantially the center in the longitudinal direction of the conveying screw 35, but the ribs 40a to 40d are formed at a plurality of positions at predetermined intervals over the entire longitudinal direction of the conveying screw 35. You may do it. However, in most cases, the warp of the conveying screw 35 occurs in the central portion in the longitudinal direction, and even if the ribs 40a to 40d are formed in the vicinity of both ends in the longitudinal direction, the effect of suppressing the deformation of the conveying screw 35 is not so much. I can't expect it. A sufficient effect can be expected if the ribs 40a to 40d are formed so as to face a range within 1/3 of the entire length of the conveying screw 35 at a substantially central portion in the longitudinal direction of the conveying screw 35.

  In addition, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the meaning of this invention. For example, in the above-described embodiment, the cleaning device 7 including the rubbing roller 21 and the cleaning blade 22 has been described. However, the toner conveying device 30 of the present invention includes, for example, the cleaning device 7 including only the cleaning blade 22 and the cleaning blade. It can replace with 22 and can apply to the cleaning apparatus of various structures, such as the cleaning apparatus 7 provided with the fur brush.

  Moreover, in the said embodiment, although the conveyance screw 35 by which the helical conveyance blade | wing 35a was continuously provided around the rotating shaft 35b is used, the conveyance blade 35a is not limited to a helical shape, For example, several half moons A plate-like plate (a plate obtained by dividing a circular plate into two parts) may be alternately arranged around the rotation shaft 35b at a predetermined inclination angle to form a conveyance blade 35a.

  In each of the above embodiments, the toner transport device 30 according to the present invention is disposed in the waste toner transport path from the cleaning device 7 to the waste toner bottle 37. However, for example, toner transport from the toner container 6 to the developing unit 5 is performed. The same applies to the route.

  The present invention can be used for a toner conveying device having a toner conveying pipe and a conveying screw disposed in the toner conveying pipe. By using the present invention, it is possible to suppress the generation of impact sound due to the collision between the conveying screw and the inner surface of the toner conveying pipe, and to effectively prevent the decrease in the fluidity and solidification of the toner due to the increase in the rotational load of the conveying screw. Can do.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 3 Photosensitive drum 7 Cleaning apparatus 21 Rub roller 22 Cleaning blade 30 Toner conveyance apparatus 31 Toner conveyance pipe 31a Upper pipe 31b Lower pipe 32 Toner carry-in port 33 Toner discharge port 35 Conveyance screw 35a Conveyance blade 35b Rotating shaft 37 Waste toner bottle 40a-40d Rib O Axis center

Claims (3)

A conveying screw having a rotating shaft and a conveying blade formed on the outer peripheral surface of the rotating shaft;
A toner conveying pipe having a circular cross section in which the conveying screw is rotatably arranged;
A toner conveying device comprising:
A plurality of ribs whose outer peripheral edges viewed from the axial direction of the rotating shaft are arcuate around the axis of the rotating shaft are formed on the conveying blade at an interval of one pitch or more of the conveying blade. And
The distance from the axis of the rotation shaft to the outer peripheral edge of each rib is equal to or slightly smaller than the radius of the inner peripheral surface of the toner transport pipe, and each rib is transported by the transport roller. It is formed by shifting the phase within a range of 180 ° or less within a range of ½ or less of the wing, and when the formation range of each rib viewed from the axial direction of the rotating shaft is combined, it exceeds 180 ° and the conveyance The rib forming range in the longitudinal direction of the screw is a substantially central portion in the longitudinal direction of the conveying screw and is within a range of 1/3 of the total length of the conveying screw.   2. The toner conveying device according to claim 1, wherein each of the ribs is formed so as to be evenly assigned to an outer peripheral edge of the conveying blade as viewed from an axial direction of the rotating shaft.   An image forming apparatus on which the toner conveying device according to claim 1 is mounted.

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