JP2018097175A - Stirring and conveying member and developing device including the same, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stirring and conveying member that can reduce stagnation of powder to improve a stirring property, a developing device including the same, and an image forming apparatus.SOLUTION: A stirring and conveying member comprises: a rotation shaft that is rotatably supported in a powder container; a first spiral blade that is formed on an outer peripheral surface of the rotation shaft and conveys powder in the axial direction with rotation of the rotation shaft; and a second spiral blade that is formed on the outer peripheral surface of the rotation shaft to be overlapped with a formation area of the first spiral blade in the axial direction, has an opposite phase to that of the first spiral blade, and has a smaller radial height than that of the first spiral blade. The first spiral blade has a first notch formed within every predetermined range from an intersection with the second spiral blade toward the upstream side in a powder conveyance direction of the first spiral blade. The second spiral blade has a second notch formed within every predetermined range from an intersection with the first spiral blade toward the upstream side in the powder conveyance direction of the second spiral blade.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a stirring and conveying member that conveys powder such as a developer while stirring, a developing device including the same, and an image forming apparatus equipped with the developing device.

  In an image forming apparatus, a latent image formed on an image carrier made of a photoreceptor or the like is developed by a developing device and visualized as a toner image. As one of such developing devices, a two-component developing method using a two-component developer is employed. This type of developing device accommodates a developer composed of a carrier and toner in a developing container, disposes a developing roller for supplying the developer to the image carrier, and stirs the developer inside the developing container. An agitating and conveying member that conveys and supplies the developing roller is provided.

  In the two-component development method, image defects such as toner scattering and fogging may occur when the charge amount of toner is not sufficient. Therefore, it is necessary to sufficiently stir and mix the toner and the carrier to charge the toner to a predetermined charge amount.

  Therefore, Patent Document 1 discloses a shaft member, a main conveyance blade that conveys powder in a first direction on one side in the axial direction along with the rotation of the shaft member, and a part of the powder along with the rotation of the shaft member. In contrast, a powder agitating and conveying member provided with a sub-conveying means for producing a conveying action in the second direction on the other side in the axial direction is disclosed, and the sub-conveying means is reversely wound with a smaller diameter than the main conveying blade ( The sub-carrier blades in the reverse phase are illustrated.

  Patent Document 2 discloses that a rotation shaft and a first spiral blade that is formed on the outer peripheral surface of the rotation shaft and conveys powder in the axial direction by rotation of the rotation shaft overlap with a formation region of the first spiral blade. And a second spiral blade formed on the outer peripheral surface of the rotating shaft, having a phase opposite to that of the first spiral blade and having a radial height lower than that of the first spiral blade. The blade and the second spiral blade have a trapezoidal cross-sectional shape that crosses the length direction of the spiral blade, and each of the first spiral blade and the second spiral blade has a trapezoidal bottom portion during one round of the rotation axis. Are formed with a plurality of first and second inflating parts that are swollen more than other parts, and the first spiral blade and the second spiral are formed at least at one location of the first inflating part during one rotation of the rotating shaft. An agitating and conveying member that intersects with a blade is disclosed.

  According to the configurations of Patent Documents 1 and 2, the second spiral blade (sub-transport blade) transports the developer in the direction opposite to the developer transport direction by the first spiral blade (main transport blade). Convection is generated in a part of the developer, and the stirring action is promoted without substantially impeding the feeding action of the first spiral blade (main conveying blade).

JP 2008-33109 A JP 2012-163731 A

  However, in the stirring and conveying members of Patent Documents 1 and 2, the developer stays near the intersection of the first spiral blade and the second spiral blade. More specifically, on the downstream side of the intersection of the first spiral blade and the second spiral blade with respect to the rotation direction of the rotation shaft (shaft member), a region sandwiched between the first spiral blade and the second spiral blade. The developer stays. For this reason, insufficient stirring of the developer occurs, and an image defect may occur.

  The present invention has been made in order to solve the above-described problems, and an object of the present invention is to provide a stirring and conveying member capable of improving the stirrability by suppressing the retention of powder, and the same. A developing device and an image forming apparatus are provided.

  In order to achieve the above object, the stirring and conveying member of the first configuration of the present invention is formed on a rotary shaft rotatably supported in a powder container and an outer peripheral surface of the rotary shaft. A first spiral blade that conveys powder in the axial direction, and is formed on the outer peripheral surface of the rotating shaft so as to overlap with the formation region of the first spiral blade in the axial direction, and has a phase opposite to that of the first spiral blade and the first And a second spiral blade having a radial height smaller than that of the spiral blade. The first spiral blade intersects with the second spiral blade at least at one place during one rotation of the rotation axis, and a predetermined range on the upstream side in the powder conveying direction of the first spiral blade from the intersection with the second spiral blade. In addition, the first notch is formed, and the second spiral blade is formed in a predetermined range on the upstream side in the powder conveying direction of the second spiral blade from the intersection with the first spiral blade. The radial height of the portion where the first notch of the first spiral blade is formed is smaller than the radial height of the portion where the second notch of the second spiral blade is not formed.

  According to the stirring and conveying member of the first configuration of the present invention, the first spiral blade has the first notch within a predetermined range upstream of the first spiral blade in the powder conveying direction from the intersection with the second spiral blade. The radial height of the portion where the first notch of the first spiral blade is formed is smaller than the radial height of the portion where the second notch of the second spiral blade is not formed. Further, the second spiral blade has a second notch formed in a predetermined range on the upstream side in the powder conveying direction of the second spiral blade from the intersection with the first spiral blade. Thereby, the powder in the region in the vicinity of the downstream side of the intersection of the first spiral blade and the second spiral blade with respect to the rotation direction of the rotation shaft passes through the first notch and the second notch and is dispersed. For this reason, the stagnant property can be improved by suppressing the retention of the powder.

Schematic showing the overall configuration of an image forming apparatus 1 equipped with the developing devices 2a to 2d of the present invention. Side surface sectional view of the developing device 2a on which the first spiral 43 and the second spiral 44 which are the stirring and conveying members of the present invention are mounted. Plan sectional drawing which shows the stirring part of the developing device 2a of this invention The partial enlarged view which looked at the 1st spiral 43 which is the stirring conveyance member of this invention from the direction perpendicular | vertical to the rotating shaft 43b. The partial enlarged view which looked at the 1st spiral 43 which is the stirring conveyance member of this invention from the direction perpendicular | vertical to the rotating shaft 43b. FIG. 5 is a partially enlarged view of the first spiral 43 that is the stirring and conveying member of the present invention as seen from the direction perpendicular to the rotation shaft 43b, and shows the structure on the back side of the first spiral 43 shown in FIG. FIG. 6 is a partially enlarged view of the first spiral 43 that is the stirring and conveying member of the present invention viewed from a direction perpendicular to the rotation shaft 43b, and shows a structure on the back side of the first spiral 43 shown in FIG.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic cross-sectional view of an image forming apparatus 1 on which developing devices 2a to 2d of the present invention are mounted. Here, a tandem color printer is shown. In the image forming apparatus 1, photosensitive drums 11a, 11b, 11c, and 11d that carry visible images (toner images) of the respective colors are disposed, and cyan, which are charged, exposed, developed, and transferred, respectively. Then, magenta, yellow, and black images are sequentially formed. Further, an intermediate transfer belt 17 that rotates in the clockwise direction in FIG. 1 is provided adjacent to each image forming unit including the photosensitive drums 11a to 11d.

  When image data is input from a host device such as a personal computer, first, the surfaces of the photosensitive drums 11a to 11d are uniformly charged by the chargers 13a to 13d. Next, the exposure device 12 emits light according to the image data, and electrostatic latent images corresponding to the image data are formed on the photosensitive drums 11a to 11d. The developing devices 2a to 2d are filled with a predetermined amount of a two-component developer (hereinafter simply referred to as a developer) containing toners of cyan, magenta, yellow, and black colors by a toner container (not shown). The toner in the developer is supplied onto the photosensitive drums 11a to 11d by the developing devices 2a to 2d and electrostatically adheres. Thereby, a toner image corresponding to the electrostatic latent image formed by exposure from the exposure device 12 is formed.

  The primary transfer rollers 26a to 26d apply an electric field at a predetermined transfer voltage between the primary transfer rollers 26a to 26d and the photosensitive drums 11a to 11d, and cyan, magenta, yellow, and yellow on the photosensitive drums 11a to 11d. A black toner image is primarily transferred onto the intermediate transfer belt 17. Toner remaining on the surfaces of the photosensitive drums 11a to 11d after the primary transfer is removed by the cleaning devices 14a to 14d.

  The transfer paper S to which the toner image is transferred is accommodated in a paper cassette 32 disposed in the lower part of the image forming apparatus 1, and the transfer paper S is transferred to a predetermined position via a paper feed roller 33a and a resist roller pair 33b. At a timing, the intermediate transfer belt 17 is conveyed to a nip portion (secondary transfer nip portion) between the secondary transfer roller 34 and the intermediate transfer belt 17 provided adjacent to the intermediate transfer belt 17. The transfer sheet S on which the toner image is secondarily transferred is conveyed to the fixing unit 18. The toner remaining on the surface of the intermediate transfer belt 17 after the secondary transfer is removed by the belt cleaning device 31.

  The transfer sheet S conveyed to the fixing unit 18 is heated and pressurized to fix the toner image on the surface of the transfer sheet S, and a predetermined full color image is formed. The transfer sheet S on which the full-color image is formed is discharged to the discharge tray 37 by the discharge roller pair 19 as it is (or after being distributed to the reverse conveyance path 40 by the branching portion 39 and images are formed on both sides).

  FIG. 2 is a side sectional view showing the configuration of the developing device 2a of the present invention. In the following description, the configuration and operation of the developing device 2a corresponding to the photosensitive drum 11a shown in FIG. 1 will be described. However, the configuration and operation of the developing devices 2b to 2d are the same as those of the developing device 2a. Is omitted.

  As shown in FIG. 2, the developing device 2a includes a developing roller 20, a magnetic roller (developer carrier) 21, a regulating blade 24, an agitating / conveying member 42, a developing container (powder container) 22, and the like. Has been.

  The developing container 22 constitutes an outline of the developing device 2a, and is partitioned into a first transfer chamber 22c and a second transfer chamber 22d by a partitioning portion 22b at the lower part thereof. The first transfer chamber 22c and the second transfer chamber 22d contain a developer composed of a carrier and toner. Further, the developing container 22 rotatably holds the stirring and conveying member 42, the magnetic roller 21, and the developing roller 20. Furthermore, the developing container 22 has an opening 22a that exposes the developing roller 20 toward the photosensitive drum 11a.

  The developing roller 20 faces the photosensitive drum 11a and is disposed on the right side of the photosensitive drum 11a with a certain interval. Further, the developing roller 20 forms a developing region D for supplying toner to the photosensitive drum 11a at a facing position close to the photosensitive drum 11a. The magnetic roller 21 is opposed to the developing roller 20 with a certain interval, and is disposed on the lower right side of the developing roller 20. Further, the magnetic roller 21 supplies toner to the developing roller 20 at a facing position close to the developing roller 20. The stirring and conveying member 42 is disposed substantially below the magnetic roller 21. Further, the regulating blade 24 is fixedly held on the developing container 22 diagonally to the left of the magnetic roller 21.

  The agitating / conveying member 42 is composed of a first spiral (first agitating and conveying member) 43 and a second spiral (second agitating and conveying member) 44. The second spiral 44 is provided in the second transfer chamber 22 d below the magnetic roller 21, and the first spiral 43 is provided in the first transfer chamber 22 c adjacent to the right side of the second spiral 44.

  The first and second spirals 43 and 44 stir the developer to charge the toner in the developer to a predetermined level. As a result, the toner is held on the carrier. In addition, communication portions (not shown) are provided at both ends in the longitudinal direction (front and back direction in FIG. 2) of the partition portion 22b that partitions the first transfer chamber 22c and the second transfer chamber 22d, and the first spiral When 43 rotates, the charged developer is transported to the second spiral 44 from one communicating portion provided in the partition portion 22b, and the developer circulates in the first transport chamber 22c and the second transport chamber 22d. Then, the developer is supplied from the second spiral 44 to the magnetic roller 21.

  The magnetic roller 21 includes a roller shaft 21a, a magnetic pole member M, and a nonmagnetic sleeve 21b made of a nonmagnetic material. The magnetic roller 21 carries the developer supplied by the stirring and conveying member 42, and only the toner from the carried developer is developed by the developing roller 20. To supply. In the magnetic pole member M, a plurality of magnets with different polarities on the outer peripheral portion formed in a sector fan shape are alternately arranged, and are fixed to the roller shaft 21a by adhesion or the like. The roller shaft 21a is supported by the developing container 22 in a non-rotatable manner within the nonmagnetic sleeve 21b with a predetermined gap between the magnetic pole member M and the nonmagnetic sleeve 21b. The non-magnetic sleeve 21b is rotated in the same direction as the developing roller 20 (clockwise direction in FIG. 2) by a driving mechanism including a motor and a gear (not shown), and a bias 56 in which the AC voltage 56b is superimposed on the DC voltage 56a is applied. Is done. On the surface of the nonmagnetic sleeve 21 b, the charged developer is carried by forming a magnetic brush by the magnetic force of the magnetic pole member M, and the magnetic brush is adjusted to a predetermined height by the regulating blade 24.

  When the nonmagnetic sleeve 21b rotates, the magnetic brush is carried and conveyed on the surface of the nonmagnetic sleeve 21b by the magnetic pole member M, and when contacting the developing roller 20, only the toner of the magnetic brush is applied to the nonmagnetic sleeve 21b. In response to the bias 56, the toner is supplied to the developing roller 20.

  The developing roller 20 includes a fixed shaft 20a, a magnetic pole member 20b, a developing sleeve 20c formed in a cylindrical shape with a nonmagnetic metal material, and the like.

  The fixed shaft 20a is supported by the developing container 22 so as not to rotate. A developing sleeve 20c is rotatably held on the fixed shaft 20a. Further, a magnetic pole member 20b made of a magnet is fixed to the developing sleeve 20c at a position facing the magnetic roller 21 by adhesion or the like. The The developing sleeve 20c is rotated in an arrow direction (clockwise direction) in FIG. 2 by a driving mechanism including a motor and a gear (not shown). Further, a developing bias 55 in which an AC voltage 55b is superimposed on a DC voltage 55a is applied to the developing sleeve 20c.

  When the developing sleeve 20c to which the developing bias 55 is applied is rotated in the clockwise direction in FIG. 2, the developing sleeve 20c is carried on the surface of the developing sleeve 20c by the potential difference between the developing bias potential and the exposed portion of the photosensitive drum 11 in the developing region D. The toner thus discharged flies to the photosensitive drum 11a. The flying toner sequentially adheres to the exposed portion on the photosensitive drum 11a rotating in the direction of arrow A (counterclockwise direction), and the electrostatic latent image on the photosensitive drum 11a is developed.

  Next, the stirring unit of the developing device 2a will be described in detail with reference to FIG. FIG. 3 is a plan cross-sectional view (a cross-sectional view taken along the line XX ′ in FIG. 2) showing the stirring unit of the developing device 2a.

  As described above, the developing container 22 includes the first transfer chamber 22c, the second transfer chamber 22d, and the partition portion 22b. In addition, the upstream communication portion (communication portion) 22e and the downstream side A communication portion (communication portion) 22f, a developer supply port (toner supply port) 22g, a developer discharge port 22h, an upstream side wall portion 22i, and a downstream side wall portion 22j are formed. In the first transfer chamber 22c, the left side in FIG. 3 is the upstream side, the right side in FIG. 3 is the downstream side, and in the second transfer chamber 22d, the right side in FIG. 3 is the upstream side, and the left side in FIG. And Therefore, the communication part and the wall part are referred to as the upstream side and the downstream side with reference to the second transfer chamber 22d.

  The partition 22b extends in the longitudinal direction of the developing container 22 and partitions the first transfer chamber 22c and the second transfer chamber 22d in parallel. The right end portion in the longitudinal direction of the partition portion 22b forms the upstream communication portion 22e together with the inner wall portion of the upstream side wall portion 22i, while the left end portion in the longitudinal direction of the partition portion 22b is the inner wall portion of the downstream side wall portion 22j. At the same time, a downstream communication portion 22f is formed. The developer passes through the first transfer chamber 22c, the upstream communication portion 22e, the second transfer chamber 22d, and the downstream communication portion 22f in order, and circulates in the developing container 22.

  The developer supply port 22g is an opening for supplying new toner and carrier into the developer container 22 from a developer supply container (not shown) provided in the upper part of the developer container 22, and is provided in the first transfer chamber 22c. Arranged on the upstream side (left side in FIG. 3).

  The developer discharge port 22h is an opening through which the developer remaining in the first and second transfer chambers 22c and 22d due to the replenishment of the developer is discharged. The developer discharge port 22h is located downstream of the second transfer chamber 22d. 2 are provided continuously in the longitudinal direction of the transfer chamber 22d.

  The first spiral 43 has a rotation shaft 43b, a first spiral blade 43a formed in a spiral shape at a constant pitch in the axial direction of the rotation shaft 43b, and the same pitch as the first spiral blade 43a in the axial direction of the rotation shaft 43b. The first spiral blade 43a has a second spiral blade 43c that is reversely wound (reverse phase). The first spiral blade 43a and the second spiral blade 43c extend to both end portions in the longitudinal direction of the first transfer chamber 22c, and are also provided to face the upstream and downstream communication portions 22e and 22f. The rotating shaft 43b is rotatably supported by the upstream side wall portion 22i and the downstream side wall portion 22j of the developing container 22. The first spiral blade 43a and the second spiral blade 43c are formed integrally with the rotating shaft 43b by a synthetic resin.

  The second spiral 44 includes a rotation shaft 44b, a first spiral blade 44a formed in a spiral shape at a constant pitch in the axial direction of the rotation shaft 44b, and the same pitch as the first spiral blade 44a in the axial direction of the rotation shaft 44b. The first spiral blade 44a has a second spiral blade 44c that is reversely wound (reverse phase). The first spiral blade 44a is reversely wound (reverse phase) with the first spiral blade 43a at the same pitch as the first spiral blade 43a of the first spiral 43. Further, the first spiral blade 44a and the second spiral blade 44c have a length equal to or longer than the axial length of the magnetic roller 21, and further extend to a position facing the upstream communication portion 22e. The rotation shaft 44b is disposed in parallel with the rotation shaft 43b, and is rotatably supported by the upstream side wall portion 22i and the downstream side wall portion 22j of the developing container 22. In addition to the first spiral blade 44a and the second spiral blade 44c, the regulating portion 52 and the discharge blade 53 are integrally disposed on the rotating shaft 44b. Detailed configurations of the first spiral blades 43a and 44a and the second spiral blades 43c and 44c will be described later.

  The restricting portion 52 blocks the developer conveyed downstream in the second conveyance chamber 22d, and enables the developer of a predetermined amount or more to be conveyed to the developer discharge port 22h. It is. The restricting portion 52 is composed of a spiral blade having a reverse winding (reverse phase) with the first spiral blade 44a provided on the rotation shaft 44b, and is set to be substantially the same as the outer diameter of the first spiral blade 44a and smaller than the pitch of the spiral blade 44a. Has been. In addition, the restricting portion 52 forms a predetermined amount of gap between the inner wall portion of the developing container 22 such as the downstream side wall portion 22 j and the outer peripheral portion of the restricting portion 52. Excess developer is discharged from this gap.

  The rotating shaft 44b extends into the developer discharge port 22h. A discharge blade 53 is provided on the rotating shaft 44b in the developer discharge port 22h. The discharge blades 53 are spiral blades facing in the same direction as the first spiral blades 44a, but have a smaller pitch than the first spiral blades 44a and have a smaller outer periphery. Therefore, when the rotating shaft 44b rotates, the discharge blade 53 also rotates, and the excess developer that has passed over the restricting portion 52 and conveyed into the developer discharge port 22h is sent to the left side in FIG. It is supposed to be discharged. The discharge blade 53, the regulating portion 52, the first spiral blade 44a, and the second spiral blade 44c are integrally formed with the rotating shaft 44b by a synthetic resin.

  Gears 61 to 64 are disposed on the outer wall of the developing container 22. The gears 61 and 62 are fixed to the rotary shaft 43b, the gear 64 is fixed to the rotary shaft 44b, and the gear 63 is rotatably held by the developing container 22 and meshes with the gears 62 and 64.

  According to the first spiral 43 configured as described above, the first spiral blade 43a is provided on the outer peripheral surface of the rotation shaft 43b, and the first spiral blade 43a is rotated in the first direction (in FIG. 3) by the rotation of the rotation shaft 43b. The developer is conveyed while stirring in the direction of arrow P). Further, on the outer peripheral surface of the rotating shaft 43b, the first spiral blade 43a has a phase opposite to that of the first spiral blade 43a between the pitches of the first spiral blade 43a (between the blades) and smaller in diameter than the first spiral blade 43a. Two spiral blades 43c are provided. The second spiral blade 43c causes the developer to convey in a second direction (arrow Q direction) opposite to the first direction by the rotation of the rotation shaft 43b.

  Further, according to the second spiral 44 having the above configuration, the first spiral blade 44a is provided on the outer peripheral surface of the rotation shaft 44b, and the first spiral blade 44a is rotated in the first direction (see FIG. 3 in the direction of arrow Q) and the developer is conveyed while stirring. Further, on the outer peripheral surface of the rotating shaft 44b, the first spiral blade 44a has a phase opposite to that of the first spiral blade 44a between the pitches of the first spiral blade 44a (between the blades) and smaller in diameter than the first spiral blade 44a. Two spiral blades 44c are provided. The second spiral blade 44c causes the developer to carry in the second direction (arrow P direction) opposite to the first direction by the rotation of the rotation shaft 44b.

  The second spiral blades 43c and 44c are positioned inward from the outer end portions of the first spiral blades 43a and 44a in the radial direction, so that the second direction generated by the rotation of the second spiral blades 43c and 44c. The transporting action occurs to a part of the developer existing in the vicinity of the rotating shafts 43b and 44b. Therefore, the conveyance action in the first direction by the first spiral blades 43a and 44a is hardly hindered.

  As described above, the second spiral blades 43c and 44c are used to cause the first spiral blades 43a and 44a to transport in the direction opposite to the developer transport direction (first direction) (second direction). As a result, convection of the developer occurs between the pitches of the first spiral blades 43a, 44a, and the first spiral blades 43a, 44a are hardly disturbed by the powder (developer) conveying action of the first spiral blades 43a, 44a. The stirring of the developer in between is promoted. Accordingly, new toner and carrier replenished from the developer replenishing port 22g are rapidly and effectively agitated with the two-component developer in the first transport chamber 22c and the second transport chamber 22d, and the first transport chamber. It is possible to effectively prevent a decrease in the developer conveyance speed in the second conveyance chamber 22d.

  The height from the rotation shafts 43b and 44b to the tips of the second spiral blades 43c and 44c (the radial height R2, see FIG. 5) is from the rotation shafts 43b and 44b to the tips of the first spiral blades 43a and 44a. If the height is less than ¼ of the height (radial height R1, see FIG. 5), sufficient convection of the developer cannot be generated between the pitches of the first spiral blades 43a and 44a, resulting in a stirring effect. May decrease. On the other hand, when R2 is larger than 1/2 of R1, the conveying force in the second direction by the second spiral blades 43c and 44c becomes too large, and the first spiral blades 43a and 44a move in the first direction. In some cases, the conveying action may be disturbed.

  Accordingly, the radial height R2 of the second spiral blades 43c, 44c is preferably not less than 1/4 and not more than 1/2 of the radial height R1 of the first spiral blades 43a, 44a. Accordingly, it is possible to effectively prevent a decrease in the conveyance speed while causing convection of the developer between the pitches of the first spiral blades 43a and 44a.

  Hereinafter, detailed configurations of the first spiral blade 43a and the second spiral blade 43c of the first spiral 43 disposed in the first transfer chamber 22c will be described with reference to FIGS. Since the first spiral blade 44a and the second spiral blade 44c of the first spiral 44 arranged in the second transfer chamber 22d have the same configuration, description thereof is omitted here.

  As shown in FIGS. 4 and 5, the first spiral blade 43 a and the second spiral blade 43 c constituting the first spiral 43 have a trapezoidal cross-sectional shape that crosses the length direction of each spiral blade. The first spiral blade 43a and the second spiral blade 43c are formed so as to intersect at two intersecting points 47 separated by 180 ° during one rotation of the rotating shaft 43b. The radial height R2 of the second spiral blade 43c is lower than the radial height R1 of the first spiral blade 43a.

  Specifically, the radial height R1 of the first spiral blade 43a is constant except around the intersection 47 (other than the first notch 50). In the first spiral blade 43a, a first notch 50 is formed in a predetermined range from the intersection 47 to the upstream side in the developer conveying direction of the first spiral blade 43a (left side in FIGS. 4 and 5). The radial height R1 of the portion of the first spiral blade 43a where the first notch 50 is formed is greater than the radial height R2 of the portion of the second spiral blade 43c where the second notch 51 described later is not formed. Is also getting smaller. As shown in FIGS. 6 and 7, the radial height R2 of the second spiral blade 43c is constant except in the vicinity of the intersection 47 (other than the second notch 51). 6 and 7 are diagrams showing the back side of the first spiral 43 shown in FIGS. 4 and 5, and the rotating shaft 43 b is made to make a half rotation (180 ° rotation) from the state of FIGS. 4 and 5. It is a figure which shows a state. The second spiral blade 43c has a second notch 51 formed in a predetermined range from the intersection 47 to the upstream side in the developer conveying direction of the second spiral blade 43c (right side in FIGS. 6 and 7).

  As a result, the developer in the region W in the vicinity of the downstream side of the intersection 47 (the lower side of FIGS. 5 and 7) with respect to the rotation direction of the rotation shaft 43 b passes through the first notch 50 and the notch 51 and is dispersed. Therefore, the retention of the developer is suppressed. In the present embodiment, since the first notch 50 is formed until it reaches the outer peripheral surface of the rotating shaft 43b, the radial height R1 of the portion where the first notch 50 of the first spiral blade 43a is formed. Is 0. Further, since the second notch 51 is formed until it reaches the outer peripheral surface of the rotating shaft 43b, the radial height R2 of the portion of the second spiral blade 43c where the second notch 51 is formed becomes zero. ing.

  Only one first notch 50 is formed while the first spiral blade 43a goes around the rotating shaft 43b. That is, the first cutouts 50 are not formed for all the intersection points 47 but are formed every other intersection point 47. Further, only one second notch 51 is formed while the second spiral blade 43c goes around the rotation shaft 43b. That is, the second notches 51 are not formed for all the intersections 47 but are formed for every other intersection 47. The first cutout 50 and the second cutout 51 are not formed at the same intersection point 47 but are formed alternately (every 180 °) with respect to the intersection point 47.

  The first notch 50 is formed at an angle of 60 ° to 120 ° in the circumferential direction of the rotating shaft 43b. The second cutout 51 is formed at an angle of 60 ° or more and less than 180 ° in the circumferential direction of the rotating shaft 43b. The first cutout 50 and the second cutout 51 are provided so that the formation regions do not overlap with each other in the axial direction of the rotation shaft 43b.

  In the present embodiment, as described above, the first spiral blade 43a has the first notch 50 formed in a predetermined range on the upstream side in the developer conveying direction of the first spiral blade 43a from the intersection 47. The radial height R1 of the portion of the first spiral blade 43a where the first notch 50 is formed is smaller than the radial height R2 of the portion of the second spiral blade 43c where the second notch 51 is not formed. Further, the second spiral blade 43c has a second notch 51 formed in a predetermined range on the upstream side of the second spiral blade 43c in the developer transport direction from the intersection 47. As a result, the developer in the region W in the vicinity of the downstream side of the intersection 47 with respect to the rotation direction of the rotating shaft 43b passes through the first notch 50 and the second notch 51 and is dispersed. For this reason, it is possible to suppress stagnant developer and improve the stirring ability.

  Similarly, in the second spiral 44, the first spiral blade 44a has a first notch 50 formed in a predetermined range upstream of the first spiral blade 44a in the developer conveying direction from the intersection 47. The radial height R1 of the portion where the first cutout 50a of 44a is formed is smaller than the radial height R2 of the portion of the second spiral blade 44c where the second cutout 51 is not formed. Further, the second spiral blade 44c has a second notch 51 formed in a predetermined range on the upstream side in the developer transport direction of the second spiral blade 44c from the intersection 47. As a result, the developer in the region W in the vicinity of the downstream side of the intersection 47 with respect to the rotation direction of the rotating shaft 44b passes through the first notch 50 and the second notch 51 and is dispersed. For this reason, it is possible to suppress stagnant developer and improve the stirring ability.

  Further, as described above, the first notch 50 is formed at an angle of 60 ° or more and 120 ° or less in the circumferential direction of the rotation shafts 43b and 44b. Thereby, it is possible to easily improve the stirring property of the developer while maintaining the developer conveying force by the first spiral blades 43a and 44a.

  In addition, as described above, the second notch 51 is formed at an angle of 60 ° or more and less than 180 ° in the circumferential direction of the rotation shafts 43b and 44b. Thereby, it is possible to easily improve the stirring property of the developer while maintaining the conveying force in the reverse direction by the second spiral blades 43c and 44c.

  Further, as described above, the first cutout 50 and the second cutout 51 are provided so as not to overlap each other in the axial direction of the rotation shafts 43b and 44b. As a result, it is possible to prevent a region where the first spiral blades 43a and 44a and the second spiral blades 43c and 44c do not exist in the axial direction of the rotating shafts 43b and 44b, so that the developer stays in that region. Can be prevented.

  Further, as described above, the radial height R1 of the portion of the first spiral blades 43a and 44a where the first notch 50 is formed is zero. As a result, the developer can easily pass through the first notch 50, so that the agitation of the developer can be sufficiently improved.

  Further, as described above, the radial height R2 of the portion of the second spiral blades 43c and 44c where the second notch 51 is formed is zero. As a result, the developer can easily pass through the second notch 51, and thus the agitation of the developer can be sufficiently improved.

  As described above, the configuration of the present invention is applied to both the first spiral 43 disposed in the first transfer chamber 22c and the second spiral 44 disposed in the second transfer chamber 22d. Thereby, in both the 1st conveyance chamber 22c and the 2nd conveyance chamber 22d, the retention of a developer can be suppressed and stirrability can be improved. Further, the developer transport speed in the first transport chamber 22c and the developer transport speed in the second transport chamber 22d can be easily made substantially the same.

  Hereinafter, the effects of the present invention will be described more specifically with reference to examples.

  Toner when the developing devices 2a to 2d shown in FIGS. 2 and 3 are mounted on the image forming apparatus 1 as shown in FIG. 1 and the configuration of the first spiral 43 in the first transfer chamber 22c is changed. The charge amount was investigated. The test was conducted in the magenta image forming section including the developing device 2a.

  In the embodiment, the diameter of the rotating shaft 43b of the first spiral 43 is 8 mm, the diameter of the first spiral blade 43a is 20 mm (the radial height R1 is 6 mm), the pitch of the first spiral blade 43a is 20 mm, and the second spiral blade. The diameter of 43c was 12 mm (the radial height R2 was 2 mm), the pitch of the second spiral blade 43c was 20 mm, and the axial length of the first spiral blade 43a and the second spiral blade 43c was 330 mm. Moreover, as shown in FIG. 5, the 1st notch 50 was formed in the 1st spiral blade 43a. Only one first notch 50 is provided while the first spiral blade 43a goes around the rotating shaft 43b, and is formed at an angle of 60 ° in the circumferential direction of the rotating shaft 43b until it reaches the outer peripheral surface of the rotating shaft 43b. did. Moreover, as shown in FIG. 7, the 2nd notch 51 was formed in the 2nd spiral blade 43c. Only one second notch 51 is provided while the second spiral blade 43c goes around the rotary shaft 43b, and is formed at an angle of 60 ° in the circumferential direction of the rotary shaft 43b until it reaches the outer peripheral surface of the rotary shaft 43b. did. A configuration using the first spiral 43 was taken as an example.

  In the comparative example, the first notch 50 and the second notch 51 were not formed in the first spiral 43. A configuration using the first spiral 43 in which other conditions were the same as those in the example was used as a comparative example.

The developing device 2a of Examples and Comparative Examples was filled with 150 cm ^{3 of} a two-component developer in which a positively chargeable toner having an average particle size of 6.8 μm and a ferrite / resin coated carrier having an average particle size of 35 μm were mixed. Then, 1 g of toner having a different color from the toner in the developing device 2a (hereinafter also referred to as replenishing toner) is replenished to the upstream end of the first transfer chamber 22c, and the downstream side from the upstream end of the first spiral 43 is supplied. The mixture was stirred and conveyed to the end. Thereafter, the replenishment toner was taken out, and the increase amount of the toner charge amount was obtained based on the charge amount of the replenishment toner before stirring and transporting measured in advance and the charge amount of the replenishment toner measured after stirring and transportation. In this experiment, the absolute humidity is performed for the case of a 20 g / m ³ For 10 g / m ^3. The results are shown in Table 1.

As shown in Table 1, in the embodiment in which the first notch 50 is formed in the first spiral blade 43a and the second notch 51 is formed in the second spiral blade 43c, the charge amount of the replenishment toner is the absolute humidity. In the case of 10 g / m ³ and 20 g / m ³ , there was an increase of 6.8 μC / g and 4.4 μC / g, respectively.

On the other hand, in the comparative example in which the first notch 50 and the second notch 51 are not formed in the first spiral 43, the charge amount of the replenishing toner is the case where the absolute humidity is 10 g / m ³ and 20 g / m ³ . Increased by 3.5 μC / g and 2.4 μC / g, respectively. Note that when the increase amount of the charge amount of the replenishment toner is 3.0 μC / g or less, a fog phenomenon may occur in which the toner adheres to a white background portion which is a non-image portion.

  From the above results, it was confirmed that the configuration of the example increased the charge amount of the toner as compared with the configuration of the comparative example. In the embodiment in which the first notch 50 and the second notch 51 are formed in the first spiral 43, this is a region W in the vicinity of the downstream side of the intersection 47 with respect to the rotation direction of the rotating shaft 43b (see FIGS. 5 and 7). This is thought to be because the developer was dispersed and passed through the first notch 50 and the second notch 51 and the stagnant property of the developer was suppressed.

  The embodiments and examples disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments and examples but by the scope of claims for patent, and includes all modifications within the meaning and scope equivalent to the scope of claims for patent.

  INDUSTRIAL APPLICABILITY The present invention can be used for a developing device used in an image forming apparatus such as a copying machine, a printer, a facsimile, and a composite machine using the electrophotographic method, and an image forming apparatus including the developing device. It can be used as a stirring and conveying member of a developing device using a two-component developer comprising:

  Further, the stirring and conveying member of the present invention includes a developer supply port 22g and a developer discharge port 22h as shown in FIG. 3, and is provided in the developing devices 2a to 2d including the magnetic roller 21 and the developing roller 20. The present invention is not limited, and can be applied to various developing devices that use a two-component developer including a toner and a carrier.

  Further, the present invention is not limited to the agitating / conveying member of the developing device, but can be applied to an agitating / conveying member that agitates and conveys powder other than the developer.

  Moreover, in the said embodiment, the structure of the 1st spiral blade 43a and the 2nd spiral blade 43c shown in FIGS. 4-7 is made into the 1st spiral 43 and 2nd conveyance chamber 22d arrange | positioned in the 1st conveyance chamber 22c. Although the example used for both the arranged 2nd spirals 44 was demonstrated, this invention is not limited to this. Depending on the specifications of the developer, the present invention may be applied only to the second spiral 44 disposed in the second transfer chamber 22d in order to enhance only the stirring effect of the second transfer chamber 22d. Alternatively, in order to enhance only the stirring effect of the first transfer chamber 22c, the present invention may be applied only to the first spiral 43 disposed in the first transfer chamber 22c. Note that in order to supply the developer in the second transfer chamber 22d to the magnetic roller 21 in a uniform state and suppress image unevenness, the developer transferred to the second transfer chamber 22d should be kept in a uniform state. preferable. Therefore, it is preferable to apply the configuration of the present invention to at least the first spiral 43 disposed in the first transfer chamber 22c.

  Moreover, in the said embodiment, although shown about the example which formed the 1st spiral blade 43a and the 2nd spiral blade 43c with the same pitch, this invention is not restricted to this, The 1st spiral blade 43a and the 2nd spiral blade 43c are shown. You may form with a mutually different pitch.

  In the above embodiment, the first cutout 50 and the second cutout 51 are shown as being alternately formed with respect to the intersection 47 (every 180 °). However, the first cutout 50 and the second cutout 51 are shown. The notch 51 may be formed with respect to the same intersection point 47. That is, you may form both the 1st notch 50 and the 2nd notch 51 with respect to every other intersection 47. FIG.

  In the above embodiment, the example in which only one first notch 50 is provided while the first spiral blade 43a goes around the rotating shaft 43b has been described. However, the present invention is not limited to this, and the first spiral is provided. Two or more first cutouts 50 may be provided while the blades 43a go around the rotating shaft 43b. Further, the first cutouts 50 may be provided for all the intersection points 47. In this case, the stirrability of the developer can be further improved.

  Similarly, in the above-described embodiment, the example in which only one second notch 51 is provided while the second spiral blade 43c goes around the rotation shaft 43b has been described. However, the present invention is not limited to this, Two or more second cutouts 51 may be provided while the spiral blade 43c goes around the rotating shaft 43b. Further, the second notches 51 may be provided for all the intersection points 47. In this case, the stirrability of the developer can be further improved.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2a-2d Developing device 21 Magnetic roller (Developer carrier)
22 Developer container (powder container)
22c 1st conveyance chamber 22d 2nd conveyance chamber 22e Upstream side communication part (communication part)
22f Downstream communication part (communication part)
22g Developer supply port (toner supply port)
42 agitating and conveying member 43 first spiral (first agitating and conveying member)
43a, 44a First spiral blades 43b, 44b Rotating shafts 43c, 44c Second spiral blades 44 Second spiral (second stirring and conveying member)
47 Intersection 50 First cutout 51 Second cutout R1 Radial height (first spiral blade)
R2 radial height (second spiral blade)

Claims (14)

A rotating shaft rotatably supported in the powder container;
A first spiral blade formed on the outer peripheral surface of the rotating shaft and conveying powder in the axial direction by rotation of the rotating shaft;
It is formed on the outer peripheral surface of the rotating shaft so as to overlap with the formation region of the first spiral blade in the axial direction, and has an opposite phase to the first spiral blade and has a radial height higher than that of the first spiral blade. A small second spiral blade,
A stirring and conveying member having
The first spiral blade is
While crossing the second spiral blade at least at one place during one rotation of the rotating shaft,
A first notch is formed in a predetermined range on the upstream side in the powder conveying direction of the first spiral blade from the intersection with the second spiral blade,
In the second spiral blade, a second notch is formed in a predetermined range on the upstream side in the powder conveying direction of the second spiral blade from the intersection with the first spiral blade,
A radial height of a portion of the first spiral blade where the first notch is formed is smaller than a radial height of a portion of the second spiral blade where the second notch is not formed. A stirring and conveying member.   2. The stirring and conveying member according to claim 1, wherein the first notch is formed at an angle of 60 ° to 120 ° in a circumferential direction of the rotating shaft.   3. The stirring and conveying member according to claim 1, wherein the second notch is formed at an angle of 60 ° or more and less than 180 ° in a circumferential direction of the rotating shaft.   4. The stirring and conveying member according to claim 1, wherein the first cutout and the second cutout are provided so that formation regions do not overlap each other in the axial direction. .   The agitation according to any one of claims 1 to 4, wherein the first spiral blade and the second spiral blade intersect at two points separated by 180 ° during one rotation of the rotating shaft. Conveying member.   6. The stirring and conveying member according to claim 5, wherein the first notch and the second notch are alternately formed with respect to the intersection provided every 180 °.   7. The stirring and conveying member according to claim 1, wherein only one of the first cutouts is formed while the first spiral blade makes one round of the rotation shaft. .   8. The stirring / conveying member according to claim 1, wherein only one second notch is formed while the second spiral blade makes a round of the rotation shaft. .   9. The stirring and conveying member according to claim 1, wherein a radial height of a portion of the first spiral blade in which the first notch is formed is zero.   The agitating / conveying member according to claim 1, wherein a radial height of a portion of the second spiral blade where the second notch is formed is zero. A developer container containing a two-component developer containing a carrier and toner;
A developer carrying member disposed in the developing container and carrying the developer in the developing container;
The stirring and conveying member according to any one of claims 1 to 10, wherein the developer in the developing container is stirred and conveyed.
A developing device comprising: The developing container includes a first transfer chamber and a second transfer chamber that are arranged in parallel to each other, and the first transfer chamber and the second transfer chamber on both ends in the longitudinal direction of the first transfer chamber and the second transfer chamber. A communication portion for communicating the chamber; and a toner replenishing port for replenishing toner to the first transfer chamber;
The developer carrying member is disposed so as to carry the developer in the second transport chamber on the surface,
In the developer container, a first agitating / conveying member that stirs and conveys the developer in the first conveying chamber in the rotation axis direction, and a developer in the second conveying chamber is agitated in the opposite direction to the first agitating / conveying member. A second agitating and conveying member for conveying, and
The developing device according to claim 11, wherein the agitating and conveying member is used as the first agitating and conveying member.   The developing device according to claim 12, wherein the stirring and conveying member is used as the second stirring and conveying member.   An image forming apparatus equipped with the developing device according to claim 11.

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