JP2011128518A - Developing device and image forming apparatus provided therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact developing device that stably discharges an excess developer from a developing container with simple configuration, and an image forming apparatus provided therewith. <P>SOLUTION: A developing device 2 includes: a developing container 22 containing a developer; and a plurality of stirring members 42 having first and second helical blades 43a and 44a and stirring and conveying the developer delivered to a developing roller 20. The developing container 22 is provided with a developer replenishing port 22g through which the developer is replenished and a developer discharge port 22h from which the excess developer is discharged. A plate-like regulating member 52 for regulating the movement of the developer to the developer discharge port 22h side is provided. The regulating member 52 is disposed at the developer discharge port 22h side of a conveyance blade 51. In the developing container 22, a downstream sidewall part 22j is formed with a space S between itself and the outer peripheral surface of the regulating member 52. The end face 22j1 of the downstream sidewall part 22j is located within the width in the axial direction of the regulating member 52. <P>COPYRIGHT: (C)2011,JPO&INPIT

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 a spiral shape is formed between the stirring member and the developer discharge port in a direction opposite to the spiral blade of the stirring member. The reverse spiral blade is integrally provided on the rotating shaft. 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 imparts 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 that excess developer moves over the reverse spiral blade to the developer discharge port and is discharged to the outside. The

  However, in the above-described prior art, the reverse spiral blade is provided between the downstream side of the conveyance path and the developer discharge port, and is formed in a spiral shape, which increases the size of the apparatus in the axial direction. Further, the developer is blocked by the reverse spiral blade, and the bulky developer moves to the developer discharge port side, but depending on the direction of the blade of the reverse spiral blade, the circumferential direction of the reverse spiral blade Since the volume of the developer is different, there is a disadvantage that the developer cannot be discharged stably.

JP 2001-265098 A (paragraphs [0021], [0023], [0024], [0028], FIG. 4)

  The present invention has been made to solve the above-described problems, and is a small-sized developing device that stably discharges excess developer from a developing container with a simple configuration, and an image forming apparatus including the developing device. The purpose is to provide.

  In order to achieve the above object, the present invention has a developing container for storing 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 section, communicating portions for communicating the respective transport paths, a developer supply port for supplying the developer, and downstream of one of the transport paths, and excess developer is discharged. In the developing device including the developer discharge port, the stirring member disposed in the one transport path is formed between the spiral blade and the developer discharge port, and the one transport path From the developer to the other conveyance path via the communication portion A conveying blade that conveys, and a plate-shaped regulating member that is formed on the developer discharge port side of the conveyance blade and regulates the movement of the developer to the developer discharge port side, are provided in the developer container. Is characterized in that a side wall portion having a gap is formed between the regulating member and an outer peripheral surface, and an end surface of the side wall portion is located between the axial widths of the regulating member.

  According to this configuration, the developer is supplied into the developer container from the developer supply port. Then, the developer replenished in the developing container is transported while being stirred by the stirring member, and is transported to the downstream side of one transport path. On the downstream side, the developer is blocked by the regulating member, and is transported from the communicating portion to the other transport path side by the rotation of the transport blades without being transported to the developer discharge port. However, the developer that is bulkier than the regulating member is conveyed to a gap between the outer peripheral surface of the regulating member and the side wall of the developing container, and overflows from the gap to the developer discharge port.

  The invention according to claim 2 is characterized in that the regulating member is provided in contact with the conveying blade.

  The invention according to claim 3 is characterized in that the regulating member is formed of a circular plate. According to this configuration, since the regulating member is formed of a circular plate, the bulk of the developer blocked by the regulating member becomes substantially constant in the circumferential direction of the rotation shaft.

  According to a fourth aspect of the present invention, the conveying blade is composed of a plurality of sheet materials parallel to the rotating shaft arranged radially around the rotating shaft, and the outer diameter of the conveying blade is the regulation It is substantially the same as the outer diameter of the member.

  According to a fifth aspect of the present invention, the side wall portion forms a part of the communicating portion on the side close to the developer discharge port together with the partition portion.

  According to a sixth 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. Then, the developer replenished in the developing container is transported while being stirred by the stirring member, and is transported to the downstream side of one transport path. On the downstream side, the developer is blocked by the regulating member, and is transported from the communicating portion to the other transport path side by the rotation of the transport blades without being transported to the developer discharge port. However, the developer that is bulkier than the regulating member is conveyed to a gap between the outer peripheral surface of the regulating member and the side wall of the developing container, and overflows from the gap to the developer discharge port as an excess developer. Therefore, the apparatus can be reduced in size with a simple configuration in which the regulating member is plate-shaped, and the excess developer can be stably discharged from the developer discharge port to the outside of the developing container.

  According to the invention described in claim 2, since the regulating member is provided in contact with the conveying blade, the apparatus becomes small in the longitudinal direction.

  According to the invention described in claim 3, since the regulating member is formed of a circular plate, the developer blocked up by the regulating member has a substantially constant bulk of the developer in the circumferential direction of the rotating shaft. Thus, the developer on the conveying blade is stably conveyed to the communicating portion without unnecessarily getting over the regulating member, and the excess developer stably overflows from the gap to the developer discharging portion.

  According to the invention described in claim 4, since the conveying blade is made of a plurality of sheet materials parallel to the rotation axis, when the conveying blade rotates, the developer on the conveying blade is reliably and rapidly conveyed to the communicating portion. The Further, since the outer diameter of the regulating member is substantially the same as the outer diameter of the conveying blade, the developer blocked by the regulating member does not unnecessarily get over the regulating member, and the developer on the conveying blade is communicated. Further, the excess developer is stably overflowed to the developer discharge portion from the gap between the outer peripheral surface of the regulating member and the side wall portion of the developing container.

  According to the invention described in claim 5, since the side wall portion forms a gap for discharging the excess developer and also forms a communication portion, development with a simple configuration and low cost without providing a special member. A container can be provided.

  According to the sixth aspect of the present invention, it is possible to provide an image forming apparatus including a small-sized developing device that stably discharges excess developer from the developing container with a simple configuration.

1 is a plan view schematically showing an overall configuration of an image forming apparatus according to an embodiment of the present invention. 1 is a cross-sectional plan view schematically showing a developing device according to an embodiment of the present invention. Sectional side view which shows the stirring part of the developing device which concerns on embodiment of this invention Sectional side view which shows the developer discharge part of the developing device which concerns on embodiment of this invention Sectional drawing of the XX direction of FIG. 4 which shows the developer discharge part of the developing device which concerns on 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 Example and comparative 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.

  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 magnetic sleeve 21b. The magnetic roller 21 carries the developer stirred by the stirring member 42, and supplies only the toner to the developing roller 20 from the carried developer. 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 in the magnetic sleeve 21b with a predetermined interval between the magnetic pole member M and the magnetic sleeve 21b. The 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. The On the surface of the magnetic 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 magnetic sleeve 21b rotates, the magnetic brush is carried and conveyed on the surface of the magnetic 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 bias 56 applied to the magnetic sleeve 21b. Accordingly, 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. An upstream side communication portion 22e and a downstream side communication portion 22f are provided at both ends in the longitudinal direction of the partition portion 22b. The developer is supplied to the first conveyance path 22c, the upstream communication portion 22e, and the second conveyance portion. It is possible to circulate through the passage 22d and the downstream communication portion 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. The second spiral 44 is a spiral blade having the same pitch as the first spiral blade 43a in the axial direction of the rotation shaft 44b and a direction opposite to the first spiral blade 43a. The second spiral blade 44a is formed. The second spiral blade 44a has a length equal to or longer than the axial length of the magnetic roller 21, and is provided to face 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, the rotation shaft 44b is provided with a transport blade 51, a regulating member 52, and a discharge blade 53.

  The conveying blade 51 is adjacent to the left side of the second spiral blade 44a and is disposed to face the downstream communication portion 22f. The conveying blades 51 are made of 4 to 6 rectangular sheet materials, have a flat surface extending in the axial direction of the rotation shaft 44b, and are arranged radially around the rotation shaft 44b. With this configuration, when the transport blade 51 rotates, the developer transported downstream (left side in FIG. 2) in the second transport path 22d is transported from the downstream communication portion 22f to the first transport path 22c. become. The conveying blade 51 is integrally formed with a shaft portion of resin or metal, and is fixed in alignment with the shaft portion on the second spiral blade 44a side. Or the conveyance blade | wing 51 is integrally formed with the rotating shaft 44b with the 2nd spiral blade 44a.

  The regulating member 52 blocks the developer transported downstream in the second transport path 22d, and transports the developer that has reached a predetermined amount or more in the transport blade 51 to the developer discharge port 22h. It is what makes it possible. The restricting member 52 is formed of a disc having a substantially the same diameter as the outer periphery of the conveying blade 51 and a relatively small width of 2 mm or less, and is provided in close contact with the conveying blade 51 on the developer discharge port 22h side of the conveying blade 51. It is done. The restricting member 52 is formed integrally with the conveying blade 51 with resin or metal. The regulating member 52 may be provided on the rotating shaft 44b so as to be separated from the conveying blade 51 instead of being provided in close contact with the conveying blade 51 perpendicular to the axial direction of the rotating shaft 44b. Alternatively, it may be inclined.

  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 blade 53 is formed of a spiral blade in the same direction as the second spiral blade 44a, but has a smaller pitch than the second spiral blade 44a and a smaller outer periphery of the blade. Therefore, when the rotation shaft 44b rotates, the discharge blade 53 also rotates, and the excess developer that has passed over the regulating member 52 and is conveyed into the developer discharge port 22h is sent to the left side of FIG. It is supposed to be discharged.

  Gears 61 to 64 are disposed on the outer walls of the upstream side wall portion 22i and the downstream side wall portion 22j. 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 upstream side wall portion 22i and meshed with the gears 62 and 64. Yes.

  Accordingly, during development, when the gear 61 is rotated by a drive source such as a motor, the first spiral blade 43a rotates together with the rotation shaft 43a, and the first spiral blade 43a moves the developer in the first transport path 22c in the direction indicated by the arrow P. Transport to. Further, when the second spiral blade 44a rotates together with the rotating shaft 44b by the gear train of the gears 62 to 64, the second spiral blade 44a transports the developer in the second transport path 22d in the direction of arrow Q. The first conveying path 22c is agitated while circulating from the upstream communication part 22e, the second conveying path 22d, and the downstream communication part 22f. Then, the stirred developer is supplied to the magnetic roller 21.

  Next, a case where developer is supplied from the developer supply port 22g will be described. When toner is consumed by development, toner is replenished from the developer replenishing port 22g into the first transport path 22c, and when the carrier deteriorates in the developing container 22, the developer replenishing port 22g A carrier or a developer containing a carrier is replenished in the first conveyance path 22c.

  The replenished developer is agitated while being circulated from the first conveyance path 22c to the upstream communication section 22e, the second conveyance path 22d, and the downstream communication section 22f from the first conveyance path 22c, as in the development. The excess developer passes over the regulating member 52 and is discharged out of the developer container 22 through the developer discharge port 22h.

  Excess developer discharge will be described in detail with reference to FIGS. FIG. 4 is a cross-sectional side view showing the developer discharge portion, and FIG. 5 is a view showing the developer discharge portion as viewed from the developer discharge port side in the XX direction of FIG.

  As shown in FIG. 4, the regulating member 52 is arranged in a space surrounded by the downstream side wall portion 22j and the front wall portion 22k in the second transport path 22d. This restriction space is formed in a substantially cylindrical shape (see FIG. 5).

  The developer discharge port 22h has a space for storing the discharge blade 53, and this discharge port space is formed in a cylindrical shape. The inner diameter of the discharge port space is smaller than the inner diameter of the restriction space and smaller than the outer periphery of the restriction member 52. Further, a gap S is formed between the restriction space and the outer peripheral surface of the restriction member 52. Furthermore, the end surface 22j1 of the downstream side wall portion 22j is at the same position in the axial direction as the surface of the regulating member 52 on the conveying blade 51 side. That is, in the downstream side wall portion 22j, the gap S is formed in the axial direction with a length corresponding to the width of the regulating member 52. The end surface 22j1 of the downstream side wall portion 22j forms a downstream side communication portion 22f together with the end surface of the partition portion 22b.

  Therefore, as shown in FIG. 5, the regulating member 52 forms a gap S over the entire circumference with respect to the downstream side wall portion 22j and the front wall portion 22k. The excess developer conveyed to the conveyance blade 51 in the second conveyance path 22d overflows from the gap S to the developer discharge port 22h.

  In the above embodiment, the end surface 22j1 of the downstream side wall portion 22j is at the same position as the upstream surface of the regulating member 52, and the gap S is formed in the axial direction with a length corresponding to the width of the regulating member 52. Although the configuration is shown, the present invention is not limited to this, and the end surface 22j1 is configured to form the gap S between the upstream surface and the downstream surface (between the axial widths) of the regulating member 52. Also good.

  According to the embodiment, the developing device 2 extends along the axial direction around the rotation shafts 43a and 44b, the developing container 22 that stores the developer, the developing roller 20 that supplies the developer to the photosensitive member 11, and the rotating shafts 43a and 44b. A plurality of stirring members 42 that have first and second spiral blades 43 a and 44 a and stir and transport the developer supplied to the developing roller 20. 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 stirring member 42 disposed in the second transport path 22d is formed between the second spiral blade 44a and the developer discharge port 22g, and the downstream side communication section from the second transport path 22d to the first transport path 22c. (Communication part) A transport blade 51 that transports the developer via 22f, and a plate shape that is formed on the developer discharge port 22g side of the transport blade 51 and regulates the movement of the developer toward the developer discharge port 22g. And a downstream side wall portion (side wall portion) 22j having a gap S between the outer circumferential surface of the regulating member 52 and the downstream side wall portion 22j. The end face 22j1 is located between the upstream side and the downstream side of the restricting member 52 in the axial direction (between the widths in the axial direction).

  According to this configuration, the developer is supplied into the developing container 22 from the developer supply port 22g. Then, the developer replenished in the developing container 22 is conveyed while being agitated by the agitating member 42 and conveyed downstream of the second conveying path 22d. On the downstream side, the developer is blocked by the regulating member 52 and is not transported to the developer discharge port 22h, but is rotated from the downstream communication portion 22f to the first transport path 22c side by the rotation of the transport blade 51. Be transported. However, the developer that is bulkier than the regulating member 52 is conveyed to the gap S between the outer peripheral surface of the regulating member 52 and the downstream side wall portion 22j, and overflows from the gap S to the developer discharge port 22h as excess developer. Get out. Therefore, the apparatus can be reduced in size with a simple configuration in which the regulating member 52 is plate-shaped, and the excess developer can be stably discharged out of the developer container 22 from the developer discharge port 22h. .

  Moreover, according to the said embodiment, the conveying blade 51 is provided in the rotating shaft 44b, and the regulating member 52 is provided in contact with the conveying blade 51, whereby the apparatus is downsized in the longitudinal direction.

  Further, according to the above embodiment, the restriction member 52 is formed of a circular plate, so that the developer blocked by the restriction member 52 has a substantially constant bulk in the circumferential direction of the rotating shaft 44b. The developer on the conveying blade 51 is stably conveyed to the downstream communication portion 22f without unnecessarily getting over the regulating member 52, and the excess developer is stably conveyed from the gap S to the developer discharge portion 22h. Overflows.

  Further, according to the above embodiment, the conveying blade 51 is composed of a plurality of sheet materials parallel to the rotating shaft 44 b arranged radially around the rotating shaft 44 b. It is substantially the same as the outer diameter. Thus, since the conveyance blade 51 is composed of a plurality of sheet materials whose plane portions extend in the axial direction of the rotation shaft 44b, when the conveyance blade 51 rotates, the developer of the conveyance blade 51 is reliably transferred to the downstream communication portion 22f. And quickly. Since the outer diameter of the regulating member 52 is substantially the same as the outer diameter of the conveying blade 51, the developer blocked by the regulating member 52 does not unnecessarily get over the regulating member 52, and the conveying blade 51 The developer is stably conveyed to the downstream communication portion 22f, and the excess developer stably overflows from the gap S to the developer discharge portion 22h.

  Moreover, according to the said embodiment, the downstream side wall part 22j forms the downstream communication part 22f with the partition part 22b. As a result, the downstream side wall portion 22j forms a clearance S for discharging the excess developer and also forms a part of the downstream side communication portion 22f. The developing container 22 is simple and inexpensive without providing a special member. Can be provided.

    In the above embodiment, the developing device includes the developing roller 20 and the magnetic roller 21, carries a magnetic brush on the magnetic roller, supplies only the toner to the developing roller, and causes the toner on the developing roller to fly to the photoreceptor. Although the applied example is shown, the present invention is not limited to this, and is applied to a developing device that pumps the developer from the stirring member to the developing roller, and supplies only the toner from the developer on the developing roller including the magnet to the photosensitive member. May be.

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

  The developing roller 20 used in Example 1 and Comparative Examples 1 and 2 has an outer diameter of 16 mm and a rotation speed of 630 rpm, and the magnetic roller 21 has an outer diameter of 20 mm and a rotation speed of 800 rpm. In the first spiral 43, the outer diameter of the first spiral blade 43a is 20 mm, the blade pitch is 30 mm (double winding), the shaft diameter of the rotating shaft 43a is 7 mm, and the rotational speed is 470 rpm. . On the other hand, the outer diameter of the second spiral blade 44a of the second spiral 44 is 20 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 470 rpm. The conveying blade 51 has four blades and the rotation speed is 470 rpm. The restricting member 52 is a disk having an outer diameter of 20 mm and has a width of 2 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 toner to the carrier 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 Example 1 and Comparative Examples 1 and 2 configured as described above, the position of the downstream side wall portion 22j in the longitudinal direction (axial direction) is different from that of the regulating member 52, and the amount of developer splattered in the discharge portion. Evaluated. 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.

  In Example 1, as shown in FIG. 4, the end surface 22j1 of the downstream side wall portion 22j is at the same position as the side surface (upstream side surface) of the conveying blade 51 of the regulating member 52, and the gap S is 1.5 mm.

  In Comparative Example 1, as shown in FIG. 6, the end surface 22j1 of the downstream side wall 22j extends to the conveying blade 51, the overlap amount LA is 3 mm, and the gap S is 1.5 mm.

  In Comparative Example 2, as shown in FIG. 7, the end face 22j1 of the downstream side wall portion 22j does not overlap the regulating member 52 in the longitudinal direction, and the overlap amount LA is 3 mm.

  FIG. 8 shows the evaluation results of the developer scattering amount of Example 1 and Comparative Examples 1 and 2. FIG. 8 is a graph in which the horizontal axis represents the stirring time and the vertical axis represents the developer scattering amount.

  In Comparative Example 1 (FIG. 6), when the developer on the transport blade 51 is transported to the downstream communication portion 22f, the developer on the regulating member 52 side collides with the downstream side wall portion 22j even if the transport blade 51 rotates. Then stop. The stopped developer is pushed out toward the developer discharge port 22h by the developer conveyed downstream by the rotation of the second spiral blade 44a. As a result, as the stirring time becomes longer, the developer scattering amount increases.

  In Comparative Example 2 (FIG. 7), when the developer on the conveying blade 51 is conveyed to the downstream communication portion 22f, the developer on the regulating member 52 side is conveyed downstream by the rotation of the second spiral blade 44a. The developer is pushed toward the developer discharge port 22h and is conveyed from the space (LA) between the regulating member 52 and the downstream communication portion 22f to the developer discharge port 22h. As a result, as the stirring time becomes longer, the developer scattering amount increases. In Comparative Example 2, since there is no possibility that the developer on the regulating member 52 side stays on the downstream side wall portion 22j, the amount of developer scattering is not increased as in Comparative Example 1.

  In Example 1, even when the stirring time was long, there was almost no scattering of the developer, and the result was good.

  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)
22j1 end face 22k front wall part 42 stirring member 43 1st spiral 43a 1st spiral blade 43b, 44b rotating shaft 44 2nd spiral 44a 2nd spiral blade (spiral blade)
51 Conveying blade 52 Regulating member 53 Discharging blade 61 to 64 Gear S S Clearance

Claims (6)

A developer container for containing the 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, and stirring the developer supplied to the developing roller A plurality of agitating members to be conveyed, 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 each of the end portions in the longitudinal direction of the partition portion. A developing device comprising a communication portion for communicating the conveyance path, a developer replenishment port for replenishing the developer, and a developer discharge port provided on the downstream side of the one conveyance path and for discharging excess developer. The stirring member disposed in the one transport path is formed between the spiral blade and the developer discharge port, and the one transport path is connected to the other transport path via the communication portion. A transport blade for transporting the developer, and the transport blade A plate-shaped regulating member that is formed on the developer discharge port side and regulates the movement of the developer to the developer discharge port side,
The developing container is formed with a side wall having a gap with the outer peripheral surface of the regulating member,
The developing device according to claim 1, wherein an end surface of the side wall portion is located between an axial width of the regulating member.     The developing device according to claim 1, wherein the regulating member is provided in contact with the conveying blade.   The developing device according to claim 1, wherein the restricting member is formed of a circular plate.   The conveyance blade is composed of a plurality of sheet materials parallel to the rotation shaft that are arranged radially around the rotation shaft, and the outer diameter of the conveyance blade is substantially the same as the outer diameter of the regulating member. The developing device according to claim 3, wherein:   5. The developing device according to claim 1, wherein the side wall portion forms a part of the communication portion on a side close to the developer discharge port together with the partition portion.   An image forming apparatus on which the developing device according to claim 1 is mounted.

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