JP5386335B2 - Developing device and image forming apparatus including the same - Google Patents

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device used in an image forming apparatus such as a copying machine, a printer, a facsimile, or a composite machine using an electrophotographic system, and an image forming apparatus including the developing device. The present invention relates to a developing device that replenishes developer and discharges excess developer, and an image forming apparatus including 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 system using a two-component developer is employed. In this type of developing device, a developer composed of a carrier and toner is accommodated in a developer container, a developing roller for supplying the developer to the image carrier is disposed, and the developer inside the developer container is conveyed and stirred. However, a stirring member for supplying the developing roller is provided.

  In this developing device, the toner is consumed by the developing operation, while the carrier is not consumed and remains in the developing device. Therefore, the carrier stirred together with the toner in the developing container deteriorates as the stirring frequency increases, and as a result, the charge imparting performance of the carrier with respect to the toner gradually decreases.

  In view of this, there has been proposed a developing device in which a developer containing a carrier is replenished in a developing container and a surplus developer is discharged to suppress a decrease in charging performance.

  For example, in Patent Document 1, two stirring members each having a rotation shaft and a spiral blade formed in a spiral shape on the outer periphery thereof are arranged in parallel in each conveyance path. A partition portion is provided between the conveyance paths, and communication portions for delivering the developer are provided at both ends of the partition portion. A developer discharge port is formed on the downstream side of the conveyance path with respect to the developer conveyance direction, and is spirally formed between the stirring member and the developer discharge port in a direction opposite to the spiral blade of the stirring member. The formed reverse spiral blade is integrally provided on the rotating shaft as a restricting portion. In this configuration, when the developer is supplied into the developing container, the developer is conveyed to the downstream side of the conveyance path while being agitated by the rotation of the agitating member. When the reverse spiral blade rotates in the same direction as the stirring member, the reverse spiral blade applies a transport force in the direction opposite to the developer transport direction by the stirring member to the developer. Due to this reverse conveyance force, the developer is blocked and bulky on the downstream side of the conveyance path, so excess developer moves over the reverse spiral blade (regulator) and moves to the developer discharge port. And discharged to the outside.

JP 2001-265098 A (paragraphs [0020] to [0024], [0028], FIG. 4)

  However, in the above-described prior art, even when the developer is not newly replenished, the developer conveyed by the spiral blade of the stirring member is located downstream of the conveyance path so as to follow the outer periphery of the spiral blade. It will move and collide with the regulating part. When this developer collides with the restricting portion, the volume of the developer differs from the outer periphery of the restricting portion depending on the axial position of the spiral blade with respect to the restricting portion. When the developer collides with the restricting portion at a position where the bulk of the developer is high, the developer moves over the restricting portion to the developer discharge port due to the momentum of the collision, and the developer is excessively discharged, There is a possibility that the amount of the developer in the developing container is not stable. In particular, in an apparatus for forming an image at a high speed, the stirring member also rotates at a high speed together with the photosensitive member, and a disadvantage that the developer is excessively discharged occurs remarkably.

  In order to prevent the developer from being excessively discharged in this way, the regulating portion is arranged apart from the communicating portion, and the developer before being conveyed to the regulating portion is moved from the communicating portion to the other conveying path. However, in this configuration, there is a problem in that the restricting portion and the developer discharge port are separated from the conveyance path, and the apparatus is enlarged in the axial direction.

  The present invention has been made to solve the above-described problems, and with a simple configuration, the excess developer can be stably discharged from the developing container, and the amount of developer in the developing container can be accurately determined. It is an object of the present invention to provide a developing device that is small in size, and an image forming apparatus including the developing device.

  In order to achieve the above object, the present invention has a developing container for containing a developer, a developing roller for supplying the developer to the image carrier, and a spiral blade extending in the axial direction around the rotation axis. A plurality of agitating members for agitating and conveying the developer supplied to the developing roller, and the developer container includes a partition portion that divides a conveyance path through which the developer is circulated and conveyed by each of the agitating members, and the partition Provided at the both ends in the longitudinal direction of the part, the communicating part for communicating the respective conveying paths, the developer supply port for supplying the developer, and the downstream side of the one conveying path, and the excess developer is discharged. In the developing device having the developer discharge port, the one stirring member disposed in the one transport path is disposed to face the developer discharge port, and the developer toward the developer discharge port side A restricting portion that restricts movement of the spiral blade and the front It is arranged between the restricting portion, and the deceleration transport unit is characterized in that it is provided to reduce the conveying speed of the developer in the one conveying path partially.

  According to this configuration, the developer is supplied into the developing container from the developer supply port, and the developer is conveyed while being stirred by the stirring member. Then, the conveyed developer moves to the downstream side of one conveyance path and is blocked by the restricting portion, and the excess developer that is bulky from the restricting portion is discharged from the outer peripheral portion of the restricting portion to the developer discharge port. Overflows. On the other hand, when the developer is not newly replenished, the conveyed developer moves to the downstream side of one of the conveying paths so as to follow the outer periphery of the spiral blade of the stirring member, and collides with the regulating portion. When the bulky developer moving in a undulating manner collides with the restricting portion, the developer conveying speed is reduced by the deceleration conveying portion, so that even if the stirring member rotates at a high speed, the developer jumps up. It is suppressed and does not get over the outer periphery of the restricting portion.

  The invention according to claim 2 is characterized in that the decelerating and conveying portion is a spiral blade having a pitch smaller than that of the spiral blade of the one stirring member. According to this configuration, when the pitch of the spiral blades as the deceleration conveyance unit is small, the conveyance speed of the developer in the deceleration conveyance unit is lower than the conveyance speed in one stirring member, and the developer collides with the regulation unit. However, the splashing of the developer is suppressed and the outer peripheral portion of the restricting portion is not overcome.

  The invention according to claim 3 is characterized in that the deceleration conveying portion is a spiral blade having an outer diameter smaller than the spiral blade of the one stirring member. According to this configuration, when the outer diameter of the spiral blade serving as the deceleration conveyance unit is small, the conveyance speed of the developer in the deceleration conveyance unit is lower than the conveyance speed in one stirring member, and the developer collides with the regulation unit. However, the splashing of the developer is suppressed and the outer peripheral portion of the restricting portion is not overcome.

  According to a fourth aspect of the present invention, the restricting portion has a phase opposite to that of the spiral blade of the one stirring member. According to this configuration, when the restricting portion composed of the spiral blades having the opposite phase rotates in the same direction as the one agitating member, the restricting portion develops the conveying force in the direction opposite to the developer conveying direction by the one agitating member. It is given to the agent. By this restricting portion, the developer is blocked on the downstream side of the conveyance path and becomes bulky, and excess developer moves over the restricting portion and moves to the developer discharge port.

  The invention according to claim 5 is characterized in that the decelerating and conveying portion is disposed to face the communicating portion. According to this configuration, when the developer is not newly replenished, the developer blocked by the restriction unit is not conveyed to the developer discharge port, but is conveyed on the one side by the rotation of the deceleration conveyance unit. It is conveyed from the path to the communication part and further conveyed to the other conveyance path side.

  According to a sixth aspect of the present invention, the developing container has a side wall portion that forms the communicating portion together with the partition portion, and the side wall portion has a gap between the outer peripheral portion of the restricting portion. It is characterized by. According to this configuration, the developer that is blocked and bulky from the restriction portion is conveyed to the gap between the outer peripheral portion of the restriction portion and the side wall portion of the developer container, and overflows from the gap to the developer discharge port.

  The invention according to claim 7 is characterized in that the decelerating and conveying portion is formed integrally with the one stirring member together with the restricting portion. According to this configuration, the speed reduction conveying unit, the regulating unit, and the spiral blade can be integrally molded with, for example, a synthetic resin via the rotation shaft.

  According to an eighth aspect of the present invention, there is provided an image forming apparatus equipped with the developing device having the above configuration.

  According to the first aspect of the present invention, the developer is supplied into the developing container from the developer supply port, and the developer is conveyed while being stirred by the stirring member. Then, the conveyed developer moves to the downstream side of one conveyance path and is blocked by the restricting portion, and the excess developer that is bulky from the restricting portion is discharged from the outer peripheral portion of the restricting portion to the developer discharge port. Overflows. Accordingly, it is possible to stably discharge the excess developer from the developer discharge port to the outside of the developing container. On the other hand, when the developer is not newly replenished, the conveyed developer moves to the downstream side of one of the conveying paths so as to follow the outer periphery of the spiral blade of the stirring member, and collides with the regulating portion. When the bulky developer moving in a undulating manner collides with the restricting portion, the developer conveying speed is reduced by the deceleration conveying portion, so that even if the stirring member rotates at a high speed, the developer jumps up. It is suppressed and does not get over the outer periphery of the restricting portion. Therefore, the amount of developer in the developing container can be accurately maintained at a desired amount, and the regulating unit need not be separated from the stirring member, and the apparatus can be downsized. Furthermore, the developing device of this embodiment can also be applied to a high-speed image forming apparatus.

  According to the second aspect of the present invention, when the pitch of the spiral blades serving as the deceleration conveyance unit is small, the developer conveyance speed in the deceleration conveyance unit is lower than the conveyance speed in one stirring member, and the developer Even if the toner collides with the restricting portion, the developer is prevented from jumping up and does not get over the outer peripheral portion of the restricting portion. Therefore, the amount of developer in the developing container can be accurately maintained at a desired amount with a simple configuration.

  Further, according to the invention described in claim 3, when the outer diameter of the spiral blade as the speed reduction transport section is small, the transport speed of the developer in the speed reduction transport section is lower than the transport speed of one stirring member, Even if the developer collides with the restricting portion, the developer is prevented from jumping up and does not get over the outer peripheral portion of the restricting portion. Therefore, the amount of developer in the developing container can be accurately maintained at a desired amount with a simple configuration.

  According to the fourth aspect of the present invention, when the restricting portion composed of the spiral blades having the opposite phase rotates in the same direction as the one stirring member, the developer conveying direction by the one stirring member is determined by the restricting portion. A reverse conveying force is applied to the developer. By this restricting portion, the developer is blocked on the downstream side of the conveyance path and becomes bulky, and excess developer moves over the restricting portion and moves to the developer discharge port, so that an appropriate amount of developer is discharged. The

  According to the fifth aspect of the present invention, when the developer is not newly replenished, the developer blocked by the restricting portion is not conveyed to the developer discharge port, and the decelerating conveyance unit. By the rotation, the sheet is reliably conveyed from one conveyance path to the communicating portion and further conveyed to the other conveyance path side. Further, even if the opening width in the longitudinal direction of the communication part is narrow, the developer is transported from one transport path to the other transport part, so that the apparatus is downsized in the longitudinal direction.

  According to the sixth aspect of the present invention, the bulky developer that is blocked by the restricting portion is conveyed to the gap between the outer peripheral portion of the restricting portion and the side wall portion of the developing container, and the developer is developed from this gap. As a result, the developer overflows and the developer is not discharged excessively. Further, since the side wall portion forms a gap for discharging the excess developer and also forms a communication portion, it is possible to provide an inexpensive developing container with a simple configuration without providing a special member.

  According to the seventh aspect of the present invention, the speed reduction conveying portion, the regulating portion, and the spiral blade can be integrally formed with, for example, a synthetic resin via a rotating shaft, and are inexpensive.

  Further, according to the invention described in claim 8, the development is small in size with a simple configuration, stably discharging excess developer from the developing container, and maintaining the amount of developer in the developing container at a desired amount with high accuracy. A high-speed image forming apparatus including the apparatus can be obtained.

1 is a plan view schematically showing an overall configuration of an image forming apparatus according to a first embodiment of the present invention. 1 is a cross-sectional plan view schematically showing a developing device according to a first embodiment of the present invention. Sectional side view which shows the stirring part of the developing device which concerns on 1st Embodiment of this invention. Sectional side view which shows the stirring part of the developing device which concerns on 2nd Embodiment of this invention. Sectional side view which shows the developer discharge part of the developing device which concerns on the comparative example of this invention Sectional side view which shows the developer discharge part of the developing apparatus which concerns on another comparative example of this invention The figure which shows the developer scattering of the developer discharge part which concerns on the comparative example of this invention The figure which shows the developer scattering of the developer discharge part which concerns on 1st Example of this invention. The figure which shows the developer scattering of the developer discharge part which concerns on 2nd Example of this invention.

  Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited to these embodiments. Further, the use of the invention and the terms shown here are not limited thereto.

(First embodiment)
FIG. 1 is a plan view schematically showing a configuration of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus 1 is a tandem type color printer, and the rotatable photoconductors 11a to 11d use an organic photoconductor (OPC photoconductor) as a photosensitive material for forming a photosensitive layer, and are black, yellow, cyan. , And magenta. Around each of the photoreceptors 11a to 11d, developing devices 2a to 2d, an exposure unit 12, chargers 13a to 13d, and cleaning devices 14a to 14d are disposed.

  The developing devices 2a to 2d are arranged to face the right sides of the photoconductors 11a to 11d, respectively, and supply toner to the photoconductors 11a to 11d. The chargers 13a to 13d are arranged on the upstream side of the developing devices 2a to 2d with respect to the rotation direction of the photosensitive member and opposed to the surfaces of the photosensitive members 11a to 11d, and uniformly charge the surfaces of the photosensitive members 11a to 11d. .

  The exposure unit 12 scans and exposes each of the photoconductors 11a to 11d based on image data such as characters and patterns input from a personal computer or the like to an image input unit (not shown). The developing device 2a ~ 2d below. The exposure unit 12 is provided with a laser light source and a polygon mirror, and a reflection mirror and a lens are provided corresponding to each of the photoreceptors 11a to 11d. Laser light emitted from the laser light source is applied to the surfaces of the photoconductors 11a to 11d from the downstream side in the photoconductor rotation direction of the chargers 13a to 13d via the polygon mirror, the reflection mirror, and the lens. Electrostatic latent images are formed on the surfaces of the photoreceptors 11a to 11d by the irradiated laser light, and the electrostatic latent images are developed into toner images by the developing devices 2a to 2d.

  The endless intermediate transfer belt 17 is stretched around the tension roller 6, the driving roller 25, and the driven roller 27. The driving roller 25 is rotationally driven by a motor (not shown), and the intermediate transfer belt 17 is circulated and driven by the rotation of the driving roller 25.

  The photoreceptors 11a to 11d are arranged below the intermediate transfer belt 17 so as to be in contact with the intermediate transfer belt 17 along the conveying direction (arrow direction in FIG. 1). The primary transfer rollers 26a to 26d face the photoconductors 11a to 11d with the intermediate transfer belt 17 interposed therebetween, and press contact with the intermediate transfer belt 17 to form a primary transfer portion. In the primary transfer portion, the toner images on the photoconductors 11a to 11d are sequentially transferred to the intermediate transfer belt 17 at a predetermined timing as the intermediate transfer belt 17 rotates. As a result, a full-color toner image is formed on the surface of the intermediate transfer belt 17 in which toner images of four colors of cyan, magenta, yellow, and black are superimposed.

  The secondary transfer roller 34 is opposed to the driving roller 25 with the intermediate transfer belt 17 interposed therebetween, and presses against the intermediate transfer belt 17 to form a secondary transfer portion. In this secondary transfer portion, the toner image on the surface of the intermediate transfer belt 17 is transferred to the paper P. After the transfer, the belt cleaning device 31 cleans the toner remaining on the intermediate transfer belt 17.

  A paper feed cassette 32 that stores paper P is disposed below the image forming apparatus 1, and a stack tray 35 that supplies manually fed paper is disposed to the right of the paper feed cassette 32. On the left side of the paper feed cassette 32, a first paper transport path 33 for transporting the paper P fed from the paper feed cassette 32 to the secondary transfer portion of the intermediate transfer belt 17 is disposed. Further, on the left side of the stack tray 35, a second paper transport path 36 for transporting paper fed from the stack tray 35 to the secondary transfer unit is disposed. Further, on the upper left side of the image forming apparatus 1, a fixing unit 18 that performs a fixing process on the sheet P on which an image is formed, and a third sheet transport that transports the sheet on which the fixing process has been performed to the sheet discharge unit 37. A path 39 is provided.

  The paper feed cassette 32 can be replenished by pulling it out of the apparatus (the front side in FIG. 1). The paper P stored therein is first fed one by one by the pick-up roller 33b and the separating roller 33a. The paper is fed out to the paper conveyance path 33 side.

  The first paper transport path 33 and the second paper transport path 36 merge before the registration roller 33c, and the registration roller 33c takes the timing of the image forming operation and the paper feeding operation on the intermediate transfer belt 17, The paper P is conveyed to the secondary transfer unit. The full-color toner image on the intermediate transfer belt 17 is secondarily transferred to the sheet P conveyed to the secondary transfer unit by the secondary transfer roller 34 to which a bias potential is applied, and is conveyed to the fixing unit 18.

  The fixing unit 18 includes a fixing belt heated by a heater, a fixing roller in contact with the fixing belt, a pressure roller disposed in pressure contact with the fixing roller with the fixing belt interposed therebetween, and a toner image is transferred. The fixing process is performed by heating and pressurizing the sheet P. After the toner image is fixed by the fixing unit 18 on the paper P, the toner image is reversed by the fourth paper conveyance path 40 as necessary, and the toner image is secondarily transferred to the back surface of the paper by the secondary transfer roller 34 to be fixed. Fixing is performed at the portion 18. The sheet on which the toner image is fixed passes through the third sheet conveyance path 39 and is discharged to the sheet discharge unit 37 by the discharge roller 19a.

  FIG. 2 is a cross-sectional plan view showing the configuration of the developing device used in the image forming apparatus 1 described above. In the following description, the configuration and operation of the developing device 2a corresponding to the photoconductor 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. Omitted, and reference numerals a to d indicating developing devices and photoconductors of the respective colors are omitted.

  As shown in FIG. 2, the developing device 2 includes a developing roller 20, a magnetic roller 21, a regulating blade 24, a stirring member 42, a developing container 22, and the like.

  The developing container 22 constitutes an outline of the developing device 2, and a lower portion of the developing container 22 is partitioned into a first transport path 22c and a second transport path 22d by a partition portion 22b. The first transport path 22c and the second transport path 22d contain a developer composed of a carrier and toner. Further, the developing container 22 rotatably holds the stirring member 42, the magnetic roller 21, and the developing roller 20. Further, the developing container 22 is formed with an opening 22 a that exposes the developing roller 20 toward the photoconductor 11.

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

  The stirring member 42 is composed of two pieces, a first spiral 43 and a second spiral 44. A second spiral 44 is provided in the second conveyance path 22 d below the magnetic roller 21, and a first spiral 43 is provided in the first conveyance path 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. Further, communication portions (not shown) are provided at both end portions in the longitudinal direction (front and rear surface direction in FIG. 2) of the partition portion 22b that partitions the first transport path 22c and the second transport path 22d, and the first spiral. When 43 rotates, the charged developer is conveyed to the second spiral 44 from one communicating portion provided in the partition 22b, and the developer circulates in the first conveyance path 22c and the second conveyance path 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 member 42, and only the toner from the carried developer is transferred to 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 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 drive 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 non-magnetic sleeve 21b rotates, the magnetic brush is carried on the surface of the non-magnetic sleeve 21b by the magnetic pole member M, and when contacted with the developing roller 20, only the magnetic brush toner is applied to the non-magnetic 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, and is fixed 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 gears (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 member 11 in the developing region D. The toner thus discharged flies to the photoconductor 11. The flying toner sequentially adheres to the exposed portion on the photoconductor 11 rotating in the direction of arrow A (counterclockwise direction), and the electrostatic latent image on the photoconductor 11 is developed.

  Next, the stirring unit of the developing device will be described in detail with reference to FIG. FIG. 3 is a cross-sectional side view showing the stirring unit.

  As described above, the developing container 22 includes the first transport path 22c, the second transport path 22d, the partition 22b, the upstream communication section 22e, and the downstream communication section 22f. A developer 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 transport path 22c, the left side of FIG. 2 is the upstream side, the right side of FIG. 2 is the downstream side, and the second transport path 22d is the right side of FIG. 2 upstream and the left side of FIG. And Therefore, the communication part and the side wall part are called upstream and downstream with respect to the second transport path 22d.

  The partition part 22b extends in the longitudinal direction of the developing container 22 and partitions the first transport path 22c and the second transport path 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 can circulate in the first conveyance path 22c, the upstream communication part 22e, the second conveyance path 22d, and the downstream communication part 22f.

  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 portion of the developer container 22, and is provided in the first transport path 22c. Arranged on the upstream side (left side in FIG. 2).

  The developer discharge port 22h is an opening for discharging the developer remaining in the first and second transport paths 22c and 22d due to the replenishment of the developer. The developer discharge port 22h is located downstream of the second transport path 22d. 2 are provided continuously in the longitudinal direction of the transport path 22d.

  A first spiral 43 is disposed in the first transport path 22c, and a second spiral 44 is disposed in the second transport path 22d.

  The first spiral 43 includes a rotation shaft 43b and a first spiral blade 43a that is provided integrally with the rotation shaft 43b and formed in a spiral shape at a constant pitch in the axial direction of the rotation shaft 43b. Further, the first spiral blade 43a extends to both end portions in the longitudinal direction of the first transport path 22c, and is 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 second spiral 44 is provided integrally with the rotation shaft 44b and the rotation shaft 44b, and faces the opposite direction to the first spiral blade 43a at the same pitch as the first spiral blade 43a in the axial direction of the rotation shaft 44b (reverse phase). And a second spiral blade 44a formed in a spiral shape with the blade. Further, the second spiral blade 44a has a length equal to or longer than the axial length of the magnetic roller 21, and further extends 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 second spiral blade 44a, a speed reduction conveyance portion 51, a restriction portion 52, and a discharge blade 53 are integrally disposed on the rotation shaft 44b.

  The deceleration conveyance unit 51 is disposed adjacent to the left side of the second spiral blade 44a and opposed to the downstream communication unit 22f. Further, the deceleration conveying unit 51 is formed in a spiral shape with a plurality of blades facing in the same direction as the second spiral blade 44a, and has a size equal to or smaller than the outer diameter of the second spiral blade 44a. It is set smaller than the pitch. The blade pitch of the decelerating conveyance unit 51 is 1/6 to 1/3 of the pitch of the second spiral blade 44a, and these blades are opposed to the opening width in the longitudinal direction of the downstream communication unit 22f. Note that the blades of the decelerating and conveying unit 51 do not have to face the entire width of the downstream communication portion 22f opening, but in this case, the blades on the regulation portion 52 side face the opening of the downstream communication portion 22f. Good.

  With this configuration, when the rotation shaft 44b rotates, the developer is transported relatively fast in the second transport path 22d by the second spiral blade 44a, but the blade pitch of the deceleration transport portion 51 is the second spiral blade 44a. Therefore, in the second conveyance path 22d in which the deceleration conveyance unit 51 is provided, the developer conveyance speed is lower than that in the second spiral blade 44a. Therefore, the developer to be transported moves in the transport path so as to follow the outer periphery of the blades of the second spiral blade 44a. However, if the pitch of the spiral blades is relatively large, the bulk of the developer is large. The developer moves fast while fluctuating. On the other hand, when the pitch of the spiral blades is relatively small as in the deceleration conveyance unit 51, the change in the bulk of the developer is small, and the developer moves slowly.

  The restriction unit 52 blocks the developer conveyed downstream in the second conveyance path 22d, and conveys the developer that has become a predetermined amount or more in the deceleration conveyance unit 51 to the developer discharge port 22h. Is possible. The restricting portion 52 is formed of a spiral blade provided on the rotating shaft 44b, is formed in a spiral shape with a blade facing in the opposite direction (in reverse phase) to the second spiral blade 44a, and the outer diameter of the second spiral blade 44a. Is set to be smaller than the pitch of the second spiral blade 44a. 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 the same direction as the second spiral blades 44a, but the pitch is smaller than that of the second spiral blades 44a and the outer periphery of the blades is small. 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 restriction portion 52, the speed reduction conveyance portion 51, and the second spiral blade 44a are integrally molded 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 43a, the gear 64 is fixed to the rotary shaft 44b, and the gear 62 and a gear (not shown) are rotatably held by the developing container 22 and mesh with the gears 62 and 64. .

  Accordingly, during development without newly replenishing the developer, when the gear 61 is rotated by a drive source such as a motor, the first spiral blade 43a is rotated together with the rotating shaft 43b, and the developer is removed by the first spiral blade 43a. The developer in the first transport path 22c is transported in the direction of arrow P, and then transported into the second transport path 22d through the upstream communication portion 22e. Further, when the second spiral blade 44a rotates together with the rotation shaft 44b interlocked with the rotation shaft 44b, the developer is transported in the direction of arrow Q by the second spiral blade 44a, and the developer is decelerated. It is conveyed to the conveyance unit 51. By the rotation of the first and second spiral blades 43a and 44a, the developer is conveyed relatively quickly while greatly changing the bulkiness thereof. On the other hand, in the vicinity of the decelerating and conveying unit 51, the fluctuation in the bulk of the developer is small due to the rotation of the decelerating and conveying unit 51, and the developer gets over the regulating unit 52 by being conveyed relatively slowly. Instead, it is transported to the first transport path 22c through the downstream communication portion 22f.

  Thus, the developer is agitated while circulating from the first conveyance path 22c to the upstream communication part 22e, the second conveyance path 22d, and the downstream communication part 22f, and the agitated developer is transferred to the magnetic roller 21. Supplied.

  Next, a case where developer is supplied from the developer supply port 22g will be described. When the toner is consumed by the development, the developer including the carrier is supplied from the developer supply port 22g into the first conveyance path 22c.

  The replenished developer is transported in the direction of the arrow P by the first spiral blade 43a in the direction of the arrow P by the first spiral blade 43a, and then passes through the upstream communication portion 22e to the second transport path 22d. It is conveyed to. Further, the developer is transported in the direction of arrow Q by the second spiral blade 44a, and is transported to the deceleration transport unit 51 by the developer in the second transport path 22d. When the restricting portion 52 rotates with the rotation of the rotating shaft 44b, the restricting portion 52 applies a transport force in the direction opposite to the developer transport direction by the second spiral blade 44a to the developer. By this restricting portion 52, the developer is blocked in the vicinity of the decelerating and conveying portion 51 and becomes bulky, and excess developer passes over the restricting portion 52 and is discharged out of the developer container 22 through the developer discharge port 22h. .

(Second Embodiment)
FIG. 4 is a cross-sectional side view showing the stirring unit of the developing device according to the second embodiment. The agitation part provided with the deceleration conveyance part different from 1st Embodiment is mainly demonstrated, and description of the same part as 1st Embodiment is abbreviate | omitted hereafter.

  The first transport path 22c, the second transport path 22d, the partition 22b, the upstream communication section 22e, the downstream communication section 22f, the developer supply port 22g, and the developer discharge port 22h of the developer container 22 are the first embodiment. This is the same arrangement and configuration. The first spiral 43 having the rotation shaft 43b and the first spiral blade 43a has the same arrangement and configuration as the first embodiment. Further, the second spiral blade 44a, the speed reducing and conveying portion 71, the restricting portion 52, and the discharge blade 53 are integrally disposed on the rotation shaft 44b of the second spiral 44, and the second spiral blade 44a, the restricting portion 52, and the discharge blade 53 are integrally provided. 53 is the same arrangement and configuration as in the first embodiment, but the decelerating conveyance unit 71 is different in configuration from the first embodiment.

  The decelerating conveyance unit 71 is disposed adjacent to the left side of the second spiral blade 44a and opposed to the downstream communication unit 22f. Further, the deceleration conveying portion 71 is formed in a spiral shape with blades facing in the same direction as the second spiral blade 44a, and is set smaller than the outer diameter of the second spiral blade 44a and smaller than the pitch of the second spiral blade 44a. ing. The number of blades of the decelerating conveyance unit 71 is one, and this blade is opposed to the downstream communication unit 22f. Note that the blade pitch of the decelerating conveyance unit 71 may be the same as the pitch of the second spiral blade 44a. Moreover, the deceleration conveyance part 71 consists of several blade | wings, and these blade | wings may oppose the opening width of the longitudinal direction of 22 f of downstream communication parts. Further, the blades of the deceleration conveying unit 71 do not have to face the entire width of the downstream communication portion 22f opening. In this case, the blades on the regulating portion 52 side face the opening of the downstream communication portion 22f. Good.

  With this configuration, when the rotation shaft 44b rotates, the developer is transported relatively fast in the second transport path 22d by the second spiral blade 44a, but the blade outer diameter of the deceleration transport portion 71 is the second spiral blade. Since the outer diameter of the blade 44a is smaller than that of the second spiral blade 44a, the developer conveying speed is lower in the second conveying path 22d where the deceleration conveying portion 71 is provided. Therefore, the developer to be transported moves in the transport path so as to follow the outer periphery of the blade of the second spiral blade 44a. However, if the outer diameter of the spiral blade is relatively large, the developer becomes bulky. The developer moves fast while the fluctuates greatly. On the other hand, when the outer diameter of the blade is relatively small like the decelerating conveyance unit 71, the change in the bulk of the developer is small, and the developer moves slowly.

  Accordingly, during development without newly replenishing the developer, when the gear 61 is rotated by a drive source such as a motor, the first spiral blade 43a is rotated together with the rotating shaft 43b, and the developer is removed by the first spiral blade 43a. The developer in the first transport path 22c is transported in the direction of arrow P, and then transported into the second transport path 22d through the upstream communication portion 22e. Further, when the second spiral blade 44a rotates together with the rotation shaft 44b interlocked with the rotation shaft 44b, the developer is transported in the direction of arrow Q by the second spiral blade 44a, and the developer is decelerated. It is conveyed to the conveyance unit 71. By the rotation of the first and second spiral blades 43a and 44a, the developer is conveyed relatively quickly while greatly changing the bulkiness thereof. On the other hand, in the vicinity of the decelerating conveyance unit 71, the fluctuation in the bulk of the developer is small due to the rotation of the decelerating conveyance unit 71, and the developer gets over the regulating unit 52 by being conveyed relatively slowly. Instead, it is transported to the first transport path 22c through the downstream communication portion 22f.

  Thus, the developer is agitated while circulating from the first conveyance path 22c to the upstream communication part 22e, the second conveyance path 22d, and the downstream communication part 22f, and the agitated developer is transferred to the magnetic roller 21. Supplied.

  Next, a case where developer is supplied from the developer supply port 22g will be described. When the toner is consumed by the development, the developer including the carrier is supplied from the developer supply port 22g into the first conveyance path 22c.

  The replenished developer is transported in the direction of the arrow P by the first spiral blade 43a in the direction of the arrow P by the first spiral blade 43a, and then passes through the upstream communication portion 22e to the second transport path 22d. It is conveyed to. Further, the developer is transported in the direction of arrow Q by the second spiral blade 44 a, and is transported to the decelerating transport unit 71. When the restricting portion 52 rotates with the rotation of the rotating shaft 44b, the restricting portion 52 applies a transport force in the direction opposite to the developer transport direction by the second spiral blade 44a to the developer. By this restricting portion 52, the developer is blocked in the vicinity of the speed reduction conveyance portion 71 and becomes bulky, and excess developer passes over the restricting portion 52 and is discharged out of the developing container 22 through the developer discharge port 22h. .

  According to the first and second embodiments, the developing device 2 includes the developing container 22 that stores the developer, the developing roller 20 that supplies the developer to the photoreceptor 11, and the shafts around the rotation shafts 43b and 44b. A plurality of stirring members 42 having first and second spiral blades 43a and 44a extending in the direction and stirring and transporting the developer supplied to the developing roller 20 are provided. The developing container 22 includes a partition 22b that partitions the first and second transport paths 22c and 22d through which the developer is circulated and transported by each stirring member 42, and first and second ends on both ends in the longitudinal direction of the partition 22b. Upstream and downstream communication portions 22e and 22f for communicating the second transport paths 22c and 22d, a developer supply port 22g for supplying the developer, and a second transport path (one transport path) 22d downstream. And a developer discharge port 22h through which excess developer is discharged. The second spiral 44 (one agitating member) disposed in the second transport path 22d is disposed to face the developer discharge port 22h and restricts the movement of the developer toward the developer discharge port 22h. 52, and between the second spiral blade 44a and the restricting portion 52, the developer conveying speed in the second conveying path 22d is reduced, and the developer is communicated via the downstream communication portion (communication portion) 22f. And a decelerating conveyance unit 51 (71) that conveys the gas to the first conveyance path 22c.

  According to this configuration, the developer is replenished into the developing container 22 from the developer replenishing port 22g, and the developer is conveyed while being agitated by the agitating member 42. Then, the developer to be transported moves to the downstream side of the second transport path 22 d and is blocked by the restricting portion 52, and excess developer that is bulky from the restricting portion 52 is developed from the outer peripheral portion of the restricting portion 52. It overflows into the agent discharge port 22h. Therefore, the excess developer can be stably discharged out of the developer container 22 from the developer discharge port 22h. On the other hand, when the developer is not newly replenished, the conveyed developer moves to the downstream side of the second conveyance path 22d so as to follow the outer periphery of the second spiral blade 44a of the second spiral 44, and is regulated. Collide with part 52. When the bulky developer moving in a undulating manner collides with the restricting portion 52, the speed at which the developer is transported is reduced by the decelerating transport unit 51 (71). However, the splashing of the developer is suppressed and the outer peripheral portion of the restricting portion 52 is not climbed over. Therefore, the amount of developer in the developing container 22 can be accurately maintained at a desired amount, and the regulating unit 52 need not be separated from the second spiral blade 44a, and the apparatus can be downsized.

  Further, according to the first and second embodiments, the restricting portion 52 is in the opposite phase to the second spiral blade 44 a of the second spiral 44. As a result, when the restricting portion 52 composed of the spiral blades having the opposite phase rotates in the same direction as the second spiral blade 44a, the restricting portion 52 causes a transport force in the direction opposite to the developer transport direction by the second spiral blade 44a. It is given to the developer. Due to the restriction portion 52, the developer is blocked and bulky on the downstream side of the second transport path 22d, and excess developer moves over the restriction portion 52 and moves to the developer discharge port 22h. Developer is discharged.

  In addition, according to the first and second embodiments, the decelerating conveyance unit 51 (71) is disposed to face the downstream communication unit 22f. As a result, when the developer is not newly replenished, the developer blocked by the restricting portion 52 is not conveyed to the developer discharge port 22h, but by the rotation of the deceleration conveying portion 51 (71), It is reliably transported from the second transport path 22d to the downstream communication portion 22f and further transported to the first transport path 22c side. Even if the opening width in the longitudinal direction of the downstream communication portion 22f is narrow, the developer is transported from the second transport path 22d to the first transport path 22c, so that the apparatus is downsized in the longitudinal direction.

  Further, according to the first and second embodiments, the developing container 22 is formed with the downstream side wall part 22j that forms the downstream side communication part 22f together with the partition part 22b, and the downstream side wall part 22j is the outer peripheral part of the regulating part 52. There is a gap between them. As a result, the developer that is blocked and bulked by the restricting portion 52 is transported to the gap between the outer peripheral portion of the restricting portion 52 and the side wall portion of the developing container 22, and overflows from the gap to the developer discharge port 22h. As a result, there is no possibility that the developer is excessively discharged. Further, since the downstream side wall portion 22j forms a gap for discharging excess developer and also forms the downstream side communication portion 22f, it is possible to provide a developing container 22 that is simple and inexpensive without providing a special member. can do.

  Further, according to the first and second embodiments, the decelerating and conveying unit 51 (71) is formed integrally with the second spiral blade 44a together with the restricting unit 52, so that the decelerating and conveying unit 51 (71) and The restricting portion 52 and the second spiral blade 44a can be integrally molded with a synthetic resin via the rotating shaft 44b, and are inexpensive.

  Further, according to the first embodiment, the decelerating and conveying unit 51 is a spiral blade having a smaller pitch than the second spiral blade 44 a of the second spiral 44. If the pitch of the spiral blades as the deceleration conveyance unit 51 is small, the conveyance speed of the developer in the deceleration conveyance unit 51 is lower than the conveyance speed of the second spiral blade 44a, and even if the developer collides with the regulation unit 52, The developer is prevented from jumping up and does not get over the outer peripheral portion of the restricting portion 52. Therefore, the developer amount in the developing container 22 can be accurately maintained at a desired amount with a simple configuration.

  Further, according to the second embodiment, the decelerating and conveying unit 71 is a spiral blade having an outer diameter smaller than that of the second spiral blade 44 a of the second spiral 44. When the outer diameter of the spiral blade serving as the deceleration conveyance unit 71 is small, the developer conveyance speed in the deceleration conveyance unit 71 is lower than the conveyance speed of the second spiral blade 44a, and the developer collides with the regulation unit 52. However, the splashing of the developer is suppressed, and the outer peripheral portion of the restricting portion 52 is not climbed over. Therefore, the developer amount in the developing container 22 can be accurately maintained at a desired amount with a simple configuration.

  In the first and second embodiments, the decelerating and conveying unit 51 (71) is a spiral blade having a smaller pitch than the second spiral blade 44a of the second spiral 44 or an outer diameter smaller than the second spiral blade 44a. However, the present invention is not limited to this, and the decelerating conveyance unit 51 (71) is configured to provide a plurality of holes in the vane so as to reduce the developer conveyance speed. May be. In this case, the same effect as described above is obtained.

  In the first and second embodiments, the restricting portion 52 is configured by a spiral blade having a phase opposite to that of the second spiral blade 44a. However, the present invention is not limited to this, and the restricting portion is a developer. A disc having a size larger than the opening of the discharge port 22h may be formed on the rotating shaft 44b, and may be disposed adjacent to the decelerating conveyance unit 51 (71) in the vicinity of the developer discharge port 22h.

  Hereinafter, Examples 1 and 2 and Comparative Examples A and B that further embody the embodiment of the present invention will be described. In addition, this invention is not limited only to a following example.

  The developing roller 20 used in Examples 1 and 2 and Comparative Examples A and B has an outer diameter of 16 mm and a rotation speed of 700 rpm, and the magnetic roller 21 has an outer diameter of 20 mm and a rotation speed of 878 rpm. In the first spiral 43, the outer diameter of the first spiral blade 43a is 18 mm, the blade pitch is 30 mm (double winding), the shaft diameter of the rotating shaft 43b is 7 mm, and the rotation speed is 500 rpm. . On the other hand, the outer diameter of the second spiral blade 44a of the second spiral 44 is 18 mm, the blade pitch is 30 mm (double winding), the shaft diameter of the rotating shaft 44b is 7 mm, and the first spiral blade 43a. And the rotation speed is 500 rpm. The opening width of the downstream communication portion 22f of the developing container 22 is 30 mm.

  The toner in the developing container 22 has an average particle size of 6.8 μm, the carrier has an average particle size of 35 μm, and the weight ratio of the toner to the carrier is 9%. The weight ratio of the carrier to the toner of the new developer replenished in the developing container 22 was 10%. 400 g of developer is accommodated in the developer container 22 (first and second transport paths 22c and 22d), and this amount is a predetermined amount that does not contain excess developer in the developer container 22.

  In the developing device configured as described above, the amount of developer splattering in the discharge unit was evaluated in accordance with the presence or absence of the deceleration conveyance unit 51 (71). The developer scattering amount is the amount of developer conveyed from the first and second conveyance paths 22c and 22d to the developer discharge port 22h.

  As shown in FIG. 3, the first embodiment uses a spiral blade having a smaller pitch than the second spiral blade 44a as the deceleration conveying portion 51, and has a blade outer diameter of 18 mm and a blade pitch of 5 mm. Furthermore, the number of blades is three.

  As shown in FIG. 4, the second embodiment uses a spiral blade having an outer diameter smaller than that of the second spiral blade 44a as the decelerating conveyance unit 71. The blade outer diameter is 12 mm and the number of blades is one. It is a sheet.

  In Comparative Example A, as shown in FIG. 5, the second spiral blade 44 a extends to the restricting portion 52. Further, in Comparative Example B, as shown in FIG. 6, the second spiral blade 44 a and the reduced speed conveyance are provided on the rotation shaft 44 b between the second spiral blade 44 a and the regulating portion 52, which faces the downstream communication portion 22 f. The part 51 (71) is not provided.

  FIG. 7 shows the evaluation results of the developer scattering amounts of Comparative Examples A and B, and FIGS. 8 and 9 show the evaluation results of the developer scattering amounts of Examples 1 and 2. In each figure, the horizontal axis represents the stirring time (unit: seconds), and the vertical axis represents the developer scattering amount (unit: g).

  In Comparative Example A shown in FIG. 7, the developer is transported to the front side of the regulating portion 52 by the second spiral blade 44a and is stopped. The stopped developer is pushed out to the developer discharge port 22h side by the developer conveyed from the upstream side, and is sprung up by the rotation of the second spiral blade 44a, and exceeds the outer peripheral portion of the restricting portion 52. It moves to the discharge port 22h side. As a result, as the stirring time becomes longer, the developer scattering amount increases.

  In Comparative Example B shown in FIG. 7, the developer is transported to the front side of the restricting portion 52 and stopped by the second spiral blade 44a. The retained developer is pushed out toward the developer discharge port 22h by the developer conveyed from the upstream side, but the amount of developer splattering is smaller than that in Comparative Example A because the developer does not spring up. However, as the stirring time becomes longer, the developer scattering amount increases.

  In Examples 1 and 2, as shown in FIGS. 8 and 9, there was almost no developer splattering even when the stirring time was long, and good results were obtained.

  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. Can be used for a developing device that replenishes the two-component developer and discharges excess developer and an image forming apparatus equipped with the developing device.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2a-2d, 2 Developing apparatus 11a-11d, 11 Photoconductor 20 Developing roller 21 Magnetic roller 22 Developing container 22b Partition part 22c 1st conveyance path (the other conveyance path)
22d Second transport path (one transport path)
22e Upstream communication part 22f Downstream communication part (communication part)
22g Developer supply port 22h Developer discharge port 22i Upstream side wall 22j Downstream side wall (side wall)
42 Stirring member 43 First spiral 43a First spiral blades 43b, 44b Rotating shaft 44 Second spiral (one stirring member)
44a Second spiral blade (spiral blade)
51, 71 Deceleration transport part 52 Restriction part 53 Discharge blades 61 to 64 Gears

Claims (7)

A developer container containing a developer;
A developing roller for supplying a developer to the image carrier;
A plurality of stirring members having a spiral blade extending in the axial direction around the rotation axis, and stirring and transporting the developer supplied to the developing roller;
The developer container is
A partition section that divides a conveyance path through which the developer is circulated and conveyed by each of the stirring members;
A communicating portion for communicating each of the transport paths on both ends in the longitudinal direction of the partition;
A developer supply port for supplying developer;
A developer outlet provided on the downstream side of one of the conveyance paths, through which excess developer is discharged;
One stirring member disposed in the one transport path is
A restricting portion that is disposed to face the developer discharge port and restricts the movement of the developer toward the developer discharge port;
A decelerating conveyance unit that is disposed between the spiral blade and the regulating unit, and partially reduces the conveyance speed of the developer in the one conveyance path;
The regulating unit are two or more sheets of spiral blade der spiral blade and opposite phase of the one stirring member,
The developing device, wherein all of the decelerating conveyance unit is disposed to face the communication unit . The reduction conveyance unit, a developing device according to claim 1, wherein a helical blade roots made of smaller pitch than the helical blade of one of the stirring members.   The developing device according to claim 1, wherein the decelerating and conveying unit is a spiral blade having an outer diameter smaller than that of the spiral blade of the one stirring member.   The spiral blade of the other stirring member arranged in the other conveyance path is in an opposite phase to the spiral blade of the one stirring member. Development device. The side wall portion that forms the communicating portion with the partition portion is formed in the developing container, according to claim 1 to claim 4 wherein the side wall portion, characterized in that a gap between the outer peripheral portion of the restricting portion The developing device according to any one of the above.   The developing device according to claim 4, wherein the deceleration conveyance unit is formed integrally with the one stirring member together with the restriction unit. The image forming apparatus in which the developing device is mounted according to any one of claims 1 to 6.

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