JP2012027243A - Developing device and image forming device equipped therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device in which a developer just supplied from a developer supply port is discharged from a developer discharge port and an imaging forming device equipped therewith.SOLUTION: A developing device 14 comprises a stirring member 23 which is rotatably pivoted to a developing container 22 and stirs and conveys a developer, a developer supplying port 22g for supplying a developer in the developing container 22, a magnetic roller 52 which is disposed facing the developer supplying port 22g from the outside of the developing container 22 and conveys a developer from the developer supplying port 22g into the developing container 22 and a developer discharging port 22h in which an excessive developer in the developing container 22 is discharged. The developer discharging port 22h is formed in a longitudinal direction of the developing container 22. The developer supplying port 22g is formed in the vicinity of the lower side of the developer discharging port 22h. A stirring member 23 rotates toward the side of the developer supplying port 22g from the side of the developer discharging port 22h. The magnetic roller 52 rotates in the same direction of the stirring member 23.

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. This type of developing device contains a developer composed of a magnetic carrier and toner in a developing container, and a developing roller for supplying the developer to the image carrier is disposed, and the developer in the developing container is conveyed and stirred. 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. Accordingly, 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 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, the developer supply port is provided on the upper wall of the developer container, the developer discharge port is provided on the downstream side in the developer transport direction with respect to the developer supply port, and the stirring member is provided on the screw. Stir and transport the developer. The pitch width of the screw of the stirring member is narrow in the vicinity of the developer discharge port, so that the developer stays in the vicinity of the developer discharge port. When the amount of developer in the developer container increases, the volume of the developer increases near the developer discharge port, and excess developer overflows from the developer discharge portion to the outside of the developer container.

  In Patent Document 2, two agitating members are provided in the developing container, and the developer circulates in the developing container by rotating the agitating member. A developer supply port is provided adjacent to the end of one stirring member, and a developer discharge port is provided adjacent to the end of the other stirring member. Developer is supplied from the developer supply port, and the developer circulated in the developer container is discharged from the developer discharge portion.

JP 2001-142301 (paragraphs [0031] to [0033], FIG. 3) Japanese Patent Laid-Open No. 9-274385 (paragraphs [0014] to [0016], FIG. 1)

  However, in Patent Documents 1 and 2 described above, when the developer is discharged from the developer discharge port, it is discharged from the developer discharge port including the developer having a good charging performance just supplied from the developer supply port. There was an inconvenience.

  The present invention has been made to solve the above-described problems, and includes a developing device that suppresses the developer just supplied from the developer supply port from being discharged from the developer discharge port, and the same. Another object of the present invention is to provide an image forming apparatus.

  In order to achieve the above object, a developing device according to a first aspect of the present invention includes: a developing container that contains a developer; and a stirring member that is rotatably supported by the developing container and that stirs and conveys the developer in the developing container. A developer replenishing port for supplying the developer into the developing container, and a developer replenishing port that is disposed to face the developer replenishing port from the outside of the developing container and conveys the developer into the developing container from the developer replenishing port. A replenishment conveyance member; and a developer discharge port through which excess developer in the developer container is discharged. The developer discharge port is formed in a side wall in a longitudinal direction of the developer container, and the developer supply port is Formed near the lower side of the developer discharge port, the stirring member rotates from the developer discharge port side toward the developer supply port side, and the supply transport member rotates in the same direction as the stirring member. It is characterized by that.

  According to a second aspect of the present invention, in the above developing device, the replenishment transport member is a magnetic roller that generates a magnetic field on the surface.

  According to a third aspect of the present invention, in the above developing device, the gap between the upper edge of the developer supply port and the magnetic roller is substantially equal to the height of the magnetic brush formed on the magnetic roller, and the developer supply A gap between the lower edge of the mouth and the magnetic roller is larger than the height of the magnetic brush.

  According to a fourth aspect of the present invention, in the above developing device, the developer replenishing port is disposed downstream of the stirring member in the developer transport direction with respect to the developer discharge port.

  According to a fifth aspect of the present invention, in the above developing device, the developer replenishing port is disposed at the same position in the developer transport direction of the stirring member with respect to the developer discharge port.

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

  According to the first invention, when the developer is supplied from the developer supply port into the developer container, the stirring member is supplied to rotate from the developer discharge port side toward the developer supply port side. The developer is conveyed from the developer replenishing port side to the side opposite to the developer replenishing port in the developing container, and further conveyed in the longitudinal direction of the developing container as the agitating member rotates. As described above, the developer supplied from the developer supply port is not immediately conveyed to the developer discharge port. Further, in the vicinity of the upper side of the developer supply port in the developer container, the agitating member and the supply transport member move in opposite directions on the opposing surface, that is, the supply transport member moves from the developer supply port side to the developer discharge port side. By rotating toward the upper side, the developer is lifted upward in the vicinity of the upper side of the developer supply port in the developer container, and the volume of the developer at the developer discharge port disposed above the developer supply port is increased. The developer having increased bulk is transported from the upstream side in the transport direction by the stirring member, and is discharged as an excess developer from the developer discharge port. Therefore, it is possible to suppress the developer just supplied from the developer supply port from being discharged from the developer discharge port.

  According to the second invention, since the replenishing and conveying member is made of a magnetic roller, a magnetic brush is formed on the surface of the replenishing and conveying member, and the developer supplied from the developer replenishing port to the developing container by this magnetic brush. Is prevented from returning into the developer supply port.

  According to the third aspect of the invention, since the gap between the upper end edge of the developer supply port and the magnetic roller is substantially equal to the height of the magnetic brush, the developer supplied to the developer container returns into the developer supply port. The gap between the lower edge of the developer replenishing port and the magnetic roller is larger than the height of the magnetic brush, so that the developer can be sufficiently supplied from the developer replenishing port into the developing container. .

  According to the fourth aspect of the present invention, the developer supply port is disposed downstream of the developer discharge port in the developer transport direction with respect to the developer discharge port, so that the developer supply port supplies the developer into the developer container. The developed developer is not immediately conveyed to the developer discharge port, but is reliably conveyed in the longitudinal direction of the developing container as the stirring member rotates.

  According to the fifth aspect of the invention, since the developer supply port is disposed at the same position in the developer transport direction of the stirring member with respect to the developer discharge port, the developer supply port is disposed above the developer supply port. The bulk of the developer at the developer discharge port becomes sufficiently high, and the excess developer can be reliably discharged from the developer discharge port.

  According to the sixth aspect of the present invention, the image forming apparatus is provided with a developing device that suppresses the developer just supplied from the developer replenishing port from being discharged from the developer discharging port, and is caused by a decrease in the charging performance of the developer. An image forming apparatus capable of effectively preventing defects can be obtained.

1 is a diagram showing a schematic configuration of an image forming apparatus equipped with a developing device according to a first embodiment of the present invention. Side surface sectional drawing which shows schematic structure of the developing device which concerns on 1st Embodiment. An upper plan view showing a cross section of a stirring unit in the developing device according to the first embodiment. The top view which shows typically arrangement | positioning of the developer supply port and developer discharge port in the stirring part which concerns on 1st Embodiment. Sectional side view which shows the state which has supplied the developer from the developer supply port of the stirring part which concerns on 1st Embodiment. Sectional side view which shows the developer supply port of the stirring part which concerns on 1st Embodiment The top view which shows typically the stirring part in the image development apparatus concerning a comparative example The figure which shows the charge amount of the discharge developer of 1st Embodiment and a comparative example. The top view which shows typically the stirring part in the developing device which concerns on 2nd Embodiment.

  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 diagram showing a schematic configuration of an image forming apparatus equipped with a developing device according to an embodiment of the present invention. The image forming apparatus 1 is provided with a sheet feeding unit 2 disposed in a lower portion thereof, a sheet conveying unit 3 disposed on a side of the sheet feeding unit 2, and an upper side of the sheet conveying unit 3. An image forming unit 4, a fixing unit 5 disposed on the discharge side of the image forming unit 4, an image reading unit 6 disposed above the image forming unit 4 and the fixing unit 5, and a hopper 110. I have.

  The paper feed unit 2 includes a plurality of paper feed cassettes 7 for containing paper 9, and the paper 9 from the paper feed cassette 7 selected from among the plurality of paper feed cassettes 7 by rotating the paper feed roller 8. Each sheet is sent out to the sheet transport unit 3.

  The paper 9 sent to the paper transport unit 3 is transported toward the image forming unit 4 via the paper transport path 10. The image forming unit 4 forms a toner image on a sheet 9 by an electrophotographic process. The image forming unit 4 is a photoconductor 11 supported so as to be rotatable in the direction of an arrow in FIG. A charging unit 12, an exposure unit 13, a developing device 14, a transfer unit 15, a cleaning unit 16, and a charge eliminating unit 17 are provided.

  The charging unit 12 includes a charging wire to which a high voltage is applied. When a predetermined potential is applied to the surface of the photoconductor 11 by corona discharge from the charging wire, the surface of the photoconductor 11 is uniformly charged. Then, when light based on the image data of the original read by the image reading unit 6 is irradiated to the photoconductor 11 by the exposure unit 13, the surface potential of the photoconductor 11 is selectively attenuated, and the surface of the photoconductor 11 is irradiated. An electrostatic latent image is formed.

  Next, the developing device 14 develops the electrostatic latent image on the surface of the photoconductor 11, and a toner image is formed on the surface of the photoconductor 11. This toner image is transferred by the transfer unit 15 to the paper 9 supplied between the photoconductor 11 and the transfer unit 15.

  The sheet 9 on which the toner image has been transferred is conveyed toward the fixing unit 5 disposed on the downstream side of the image forming unit 4 in the sheet conveying direction. In the fixing unit 5, the sheet 9 is heated and pressed by the heating member 18 and the pressure roller 19, and the toner image is melted and fixed on the sheet 9. Next, the sheet 9 on which the toner image is fixed is discharged onto the discharge tray 21 by the discharge roller pair 20.

  After the transfer by the transfer unit 15, the toner remaining on the surface of the photoconductor 11 is removed by the cleaning unit 16, and the residual charge on the surface of the photoconductor 11 is removed by the charge eliminating unit 17. Then, the photosensitive member 11 is charged again by the charging unit 12, and image formation is performed in the same manner. When the developer in the developing device 14 becomes a predetermined amount or less, the developer is supplied from the hopper 110 to the developing device 14.

  Next, the developing device will be described with reference to FIG. FIG. 2 is a side view showing a cross section of a schematic configuration of a developing device used in the image forming apparatus 1.

  The developing device 14 includes a developing container 22 that stores a two-component developer composed of toner and a magnetic carrier, first and second stirring members 23 and 24 that stir the developer, a developing roller 27, and a regulating member 28. It has.

  The developing container 22 constitutes an outline of the developing device 14, and is partitioned into a first transport path 22c and a second transport path 22d by a partitioning portion 22b at a lower portion thereof. The first transport path 22c and the second transport path 22d contain a developer composed of a magnetic carrier and toner. Further, the developing container 22 holds the first and second stirring members 23 and 24 and the developing roller 27 rotatably. Further, the developing container 22 has an opening that exposes the developing roller 27 toward the photoconductor 11.

  The second stirring member 24 is provided in the second conveyance path 22d at the lower right of the developing roller 27, and the first stirring member 23 is adjacent to the right side of the second stirring member 24 and in the first conveyance path 22c. Provided.

  The first and second stirring members 23 and 24 stir the developer to charge the toner in the developer to a predetermined level. Thus, the toner is held on the magnetic carrier. Further, communication portions (not shown) are provided at both end portions in the longitudinal direction (front and back direction of the paper surface of FIG. 2) of the partition portion 22b that partitions the first transport path 22c and the second transport path 22d. When the agitating member 23 rotates, the charged developer is transported from one communicating portion provided in the partition 22b to the second transport path 22d, and the developer passes through the first transport path 22c and the second transport path 22d. Circulate. Then, the developer is supplied from the second stirring member 24 to the developing roller 27.

  The developing roller 27 includes a fixed magnet body 25 and a developing sleeve 26. The developing sleeve 26 is made of a cylindrical nonmagnetic material and is rotatably supported by the developing container 22 at a position adjacent to the second stirring member 24. The fixed magnet body 25 is a permanent magnet fixed in the developing sleeve 26 and generates a magnetic field toward the developing sleeve 26. Further, the developing roller 27 is exposed from the opening of the developing container 22 and faces the photosensitive member 11 that is an image carrier at a predetermined interval. This facing area is a developing area D for supplying the developer carried on the developing sleeve 26 toward the photoreceptor 11. Further, a developing bias 29 in which alternating current is superimposed on direct current is applied to the developing sleeve 26 in order to supply toner to the photoreceptor 11.

  The regulating member 28 regulates the developer carried on the surface of the developing sleeve 26 to a predetermined layer thickness. The regulating member 28 has a blade shape and has a predetermined interval between the developing sleeve 26 and the surface of the developing sleeve 26. And attached to the developing container 22.

  The developer supplied from the second stirring member 24 is carried on the surface of the developing sleeve 26 by the magnetic force of the fixed magnet body 25 in the developing sleeve 26. The carried developer is regulated to a predetermined layer thickness by the regulating member 28, and is conveyed toward the developing flow area D by the rotation of the developing sleeve 26 in the arrow direction. When a developing bias 29 is applied to the developing sleeve 26, a potential difference is generated between the developing sleeve 26 and the photoconductor 11 in the developing region D, and the toner on the developing sleeve 26 is supplied to the photoconductor 11 and the photoconductor. The electrostatic latent image on 11 is developed into a toner image.

  Next, the stirring unit of the developing device will be described in detail with reference to FIG. FIG. 3 is a plan view of the developing device as seen from above the cross section of the stirring unit.

  As described above, the developer container 22 is formed with the first transport path 22c, the second transport path 22d, the partition 22b, and the communication sections 22e and 22f. In addition, the developer supply port 22g (see FIG. 4). And a developer discharge port 22h (see FIG. 4).

  The partition 22b of the developing container 22 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. Communication portions 22e and 22f are provided at both end portions in the longitudinal direction of the partition portion 22b, and the developer is contained in the first conveyance path 22c, the communication section 22e, the second conveyance path 22d, and the communication section 22f. It is possible to circulate.

  A first stirring member 23 is disposed in the first transport path 22c, and a second stirring member 24 is disposed in the second transport path 22d.

  The 1st stirring member 23 has the rotating shaft 23b, the 1st spiral blade 23a, the stirring rib 23c, and the reverse spiral blade 23d.

  The rotation shaft 23 b is rotatably supported on the side wall of the developing container 22. The first spiral blades 23a are provided integrally with the rotation shaft 23b, and are formed in a spiral shape at a constant pitch in the axial direction of the rotation shaft 23b. The first spiral blade 23a extends in the longitudinal direction of the first transport path 22c and is provided to face the communication portion 22f. The stirring rib 23c is formed between the first spiral blades 23a in a flat plate shape, and is provided integrally with the rotating shaft 23b. By this stirring rib 23c, the developer is further stirred while being transported in the first transport path 22c. The reverse spiral blade 23d is a blade having a phase opposite to that of the first spiral blade 23a and is formed at least by one pitch, and is provided integrally with the rotation shaft 23b so as to face the communication portion 22e. When the reverse spiral blade 23d rotates, the developer conveyed to the downstream side (right side in FIG. 3) in the first conveyance path 22c is conveyed from the communication portion 22e to the second conveyance path 22d.

  The second stirring member 24 has a rotating shaft 24b, a second spiral blade 24a, and a reverse spiral blade 24d.

  The rotating shaft 24b is disposed in parallel with the rotating shaft 23b and is rotatably supported on the side wall of the developing container 22. The second spiral blades 24a are provided integrally with the rotary shaft 24b, and are formed in a spiral shape at a constant pitch in the axial direction of the rotary shaft 24b. The second spiral blade 24a is provided so as to extend beyond the axial length of the developing roller 27 in the second conveyance path 22d, and is provided to face the communication portion 22e. The reverse spiral blade 24d is a blade having a phase opposite to that of the second spiral blade 24a, and is formed for at least one pitch, and is provided integrally with the rotating shaft 24b so as to face the communication portion 22f. When the reverse spiral blade 24d rotates, the developer conveyed to the downstream side (left side in FIG. 3) in the second conveyance path 22d is conveyed from the communication portion 22f to the first conveyance path 22c.

  Accordingly, when the rotating shaft 23b is rotated by a driving source such as a motor or a gear train (not shown) during development, the first spiral blade 23a rotates together with the rotating shaft 23b, and the first spiral blade 23a is in the first transport path 22c. The developer is conveyed in the direction of arrow P. When the rotary shaft 24b is reversely rotated at the same rotational speed as the rotary shaft 23b in conjunction with the rotary shaft 23b, the second spiral blade 24a transports the developer in the second transport path 22d in the direction of the arrow Q. From the first transport path 22c, stirring is performed while circulating through the communication portion 22e, the second transport path 22d, and the communication portion 22f in order. Then, the developer is uniformly supplied from the second transport path 22d in the axial direction of the developing roller 27.

  Next, replenishment of new developer and discharge of excess developer will be described with reference to FIGS. FIG. 4 is a plan view schematically showing the vertical arrangement of the developer supply port and the developer discharge port in the agitation section, and FIG. 5 is a cross section showing a state where the developer is supplied from the developer supply port. FIG. 6 is a side view, and FIG. 6 is a cross-sectional side view showing a developer supply port.

  As shown in FIG. 3, in order to supply a new developer and discharge a surplus developer, a developer supply port 22g and a developer discharge port 22h (FIG. 4, FIG. 5), a magnetic roller 52 which is a replenishment conveying member, a conveying screw 51, and a conveying pipe 53 are provided.

  The developer supply port 22g is an opening for supplying a new developer into the developer container 22, and is provided on the side wall 22p in the longitudinal direction of the developer container 22 on the upstream side (left side in FIG. 3) of the first transport path 22c. It is formed.

  The developer discharge port 22h (see FIG. 5) is an opening for discharging the developer remaining in the developer container 22 due to replenishment of the developer, and is formed on the side wall 22p in the longitudinal direction of the developer container 22. Further, it is formed in the vicinity of the developer supply port 22g (see FIG. 4).

  As shown in FIG. 4, the developer discharge port 22h is arranged above the rotation shaft 23b of the first stirring member 23, and the developer supply port 22g is below the developer discharge port 22h and in the developer transport direction. It is arranged at a position near the downstream side (in the direction of the arrow in FIG. 4). In the developer transport direction, the opening width of the developer supply port 22g is formed to be approximately the same as the opening width of the developer discharge port 22h.

  Returning to FIG. 3, the transport pipe 53 is a pipe that connects the hopper 110 (see FIG. 1) and the developer supply port 22 g and passes the developer from the hopper 110 to the developer supply port 22 g. The roller 52 is rotatably supported.

  The conveyance screw 51 is provided integrally with the rotation shaft and has blades formed in a spiral shape at a constant pitch in the axial direction. When the conveyance screw 51 rotates, the developer in the hopper 110 is conveyed to the magnetic roller 52 side while stirring.

  The magnetic roller 52 transports the developer in the transport pipe 53 into the developing container 22 through the developer supply port 22g, and is provided integrally with the rotating shaft of the transport screw 51, and is a magnetic material such as a permanent magnet. Consists of. Accordingly, a magnetic field is generated on the outer peripheral surface of the magnetic roller 52, and when the developer is transported from the transport screw 51 to the magnetic roller 52, the developer adheres to the outer peripheral surface of the magnetic roller 52 to form a magnetic brush. Further, the magnetic roller 52 is disposed oppositely near the developer supply port 22g. When the magnetic roller 52 rotates, the developer on the magnetic roller 52 is conveyed to the developer supply port 22g side, and the developer in the developer container 22 is transferred from the developer supply port 22g by the magnetic brush on the magnetic roller 52. Returning to the transport pipe 53 is prevented.

  The developer replenishment and discharge will be described in detail with reference to FIG. As described above, the developer supply port 22g is disposed below the developer discharge port 22h. The first stirring member 23 rotates in the direction of arrow K, and the magnetic roller 52 rotates in the direction of arrow M, like the first stirring member 23.

  By the rotation of the magnetic roller 52 in the arrow M direction, the developer in the transport pipe 53 is transported from the lower side of the developer supply port 22g toward the developer container 22. Then, the developer conveyed toward the developing container 22 by the magnetic roller 52 passes under the first stirring member 23 (arrow Z) as the first stirring member 23 rotates in the arrow K direction. (Through the direction), the first agitating member 23 is conveyed to the first conveying path 22c opposite to the developer supply port 22g. Further, the rotation of the first agitating member 23 in the direction of arrow K causes the developer to be transported downstream (in the direction of arrow P in FIG. 3) in the developer transport direction within the first transport path 22c, and further to the communication portion 22e. (Refer to FIG. 3) is conveyed to the second conveyance path 22d and supplied to the developing roller 27.

  Further, when the magnetic roller 52 rotates in the same direction as the first stirring member 23, the magnetic roller 52 and the first stirring member 23 are in the vicinity of the developer supply port 22g where the magnetic roller 52 and the first stirring member 23 face each other. Move in opposite directions on the facing surface. In other words, the magnetic roller 52 rotates from the developer supply port 22g side toward the developer discharge port 22h side, so that the developer is moved upward in the vicinity of the upper side of the developer supply port 22g of the first conveyance path 22c. As a result, the developer becomes bulky at the developer discharge port 22h disposed above the developer supply port 22g. This developer contains a large amount of developer that is conveyed from the upstream side in the first conveyance path 22c by the first agitating member 23, that is, from the second conveyance path 22d (see FIG. 3) side and used for development. As a surplus developer, the developer passes over the developer discharge port 22h and is discharged to the discharge pipe 58. Then, the toner is conveyed to a developer recovery unit (not shown) by a discharge screw 56 rotatably provided in the discharge pipe 58.

  As shown in FIG. 6, when the developer is transported from the transport screw 51 (see FIG. 3) to the magnetic roller 52, the developer adheres to the surface of the magnetic roller 52 and the magnetic brush B is formed. Here, the gap between the developer supply port 22g and the magnetic roller 52 is not uniform on the upper side and the lower side of the magnetic roller 52 but is biased. That is, the gap below the developer supply port 22g with respect to the magnetic roller 52 (the length Y between the outer peripheral surface of the magnetic roller 52 and the developer supply port 22g in the normal direction of the magnetic roller 52) is relatively large. The developer is allowed to pass sufficiently.

  On the other hand, the gap above the developer supply port 22g with respect to the magnetic roller 52 (the length X between the outer peripheral surface of the magnetic roller 52 and the developer supply port 22g in the normal direction of the magnetic roller 52) is set to the height of the magnetic brush B. By setting the length to an appropriate length, the developer in the first transport path 22 c does not flow backward to the transport pipe 53 as the magnetic roller 52 rotates in the direction of arrow M.

  That is, when the magnetic roller 52 rotates in the direction of arrow M, the developer in the transport pipe 53 is transported from the lower side of the developer supply port 22g toward the developer container 22. When the magnetic roller 52 rotates in the direction of arrow M, the developer near the developer supply port 22g in the first transport path 22c moves into the transport pipe 53 from the developer supply port 22g as the magnetic roller 52 rotates. Although the developer tries to return, the developer is blocked by the magnetic brush B and does not return from the first transport path 22 c into the transport pipe 53.

  Next, the charge amount of the developer discharged from the developer discharge port 22h in this embodiment is evaluated together with a comparative example.

  FIG. 7 is a plan view schematically showing a stirring unit according to a comparative example. The arrangement, configuration, and opening width of the first stirring member 23 and the developer discharge port 22h of the comparative example are the same as those of the present embodiment shown in FIG. 4, and the developer is conveyed in the direction of the arrow in FIG. In the comparative example, a developer supply port 22g having an opening of the same size as the developer discharge port 22h is disposed on the downstream side of the developer discharge port 22h in the developer transport direction, and the developer discharge port 22h It arrange | positions at the same height (the same height from the bottom face of the 1st conveyance path 22c). In the comparative example, the magnetic roller 52 is not provided.

In the configuration of this embodiment and the comparative example, after printing 100 × 10 ³ originals with a printing rate of 4%, new developer is supplied into the developer container 22 from the developer supply port 22g, and the first and second developers are supplied. The stirring members 23 and 24 are rotated. The developer overflowing from the developer discharge port 22h was collected, and the charge amount distribution was measured with a charge amount distribution measuring device (Espert Analyzer, manufactured by Hosokawa Micron Corporation).

  The measurement results are shown in FIG. In the graph of FIG. 8, the horizontal axis represents the charge amount (unit: nC / m), and the vertical axis represents the frequency (unit:%) at which the developer is generated at each charge amount. In FIG. 8, when comparing the frequency of occurrence of the developer having a charge amount of 0 nC / m or less between this embodiment and the comparative example, the frequency in the comparative example is 5.7%. In this embodiment, the frequency is 28.7%.

  That is, in this embodiment, a large amount of developer with a charge amount of 0 nC / m or less, that is, with a deteriorated charging performance, is discharged relative to the comparative example, and the discharge of good developer is suppressed.

  According to the first embodiment, the developing device 14 includes the developing container 22 that stores the developer, and the stirring member 23 that is rotatably supported by the developing container 22 and stirs and conveys the developer in the developing container 22. A developer replenishing port 22g for supplying the developer into the developing container 22, and a developer replenishing port 22g that is arranged to face the developer replenishing port 22g from the outside of the developing container 22, and the developer is supplied into the developing container 22 A magnetic roller 52 (a replenishment conveyance member) for conveyance and a developer discharge port 22h for discharging excess developer in the developer container 22 are provided. The developer discharge port 22h is formed in the longitudinal side wall 22p of the developer container 22, the developer supply port 22g is formed near the lower side of the developer discharge port 22h, and the stirring member 23 is developed from the developer discharge port 22h side. The magnetic roller 52 rotates in the same direction as the stirring member 23. The magnetic roller 52 rotates toward the agent supply port 22g.

  According to this configuration, when the developer is supplied into the developer container 22 from the developer supply port 22g, the stirring member 23 rotates from the developer discharge port 22h side toward the developer supply port 22g side. The supplied developer is conveyed in the developing container 22 from the developer supply port 22g side to the side opposite to the developer supply port 22g with respect to the stirring member 23. Further, as the stirring member 23 rotates, the length of the developer container 22 is increased. Conveyed in the direction. Thus, the developer supplied from the developer supply port 22g is not immediately conveyed to the developer discharge port 22h. Further, in the vicinity of the upper side of the developer supply port 22g in the developer container 22, the stirring member 23 and the magnetic roller 52 move in opposite directions on the opposing surface, that is, the magnetic roller 52 moves from the developer supply port 22g side to the developer. By rotating toward the discharge port 22h, the developer is lifted upward in the vicinity of the developer supply port 22g in the developer container 22, and the developer discharge port 22h disposed above the developer supply port 22g. The bulk of the developer increases. The developer having increased bulk is transported from the upstream side in the transport direction by the stirring member 23, and is discharged as an excess developer from the developer discharge port 22h. Therefore, it is possible to prevent the developer just supplied from the developer supply port 22g from being discharged from the developer discharge port 22h.

  Further, according to the first embodiment, the gap X between the upper end edge of the developer supply port 22g and the magnetic roller 52 is substantially equal to the height of the magnetic brush formed on the magnetic roller 52, and the developer supply port 22g The gap Y between the lower edge and the magnetic roller is larger than the height of the magnetic brush.

  According to this configuration, since the gap X between the upper end edge of the developer supply port 22g and the magnetic roller 52 is substantially equal to the height of the magnetic brush, the developer supplied to the developer container 22 returns into the developer supply port 22g. Since the gap Y between the lower edge of the developer supply port 22g and the magnetic roller is larger than the height of the magnetic brush, the developer is sufficiently supplied into the developer container 22 from the developer supply port 22g. be able to.

  Further, according to the first embodiment, the developer supply port 22g is disposed below the developer discharge port 22h and downstream of the stirring member 23 in the developer transport direction. As a result, the developer supplied into the developer container 22 from the developer supply port 22g is not immediately conveyed to the developer discharge port 22h, and the developer container 22 is reliably moved in the longitudinal direction as the stirring member 23 rotates. It is conveyed to.

(Second Embodiment)
FIG. 9 is a plan view schematically showing a stirring unit according to the second embodiment. In the second embodiment, the developer discharge port 22h is disposed above the rotation shaft 23b of the first stirring member 23, and the developer supply port 22g is below the developer discharge port 22h in the developer transport direction ( (In the direction of the arrow in FIG. 4). The magnetic roller 52 (not shown) is rotatably disposed in the vicinity of the developer supply port 22g in the transport pipe 53 (see FIG. 6), as in the first embodiment, and the developer supply port 22g is provided in the magnetic roller 52. The gap is formed so as to be biased with respect to the vertical direction. In the developer transport direction, the opening width of the developer supply port 22g is formed longer than the opening width of the developer discharge port 22h, and the developer supply port 22g is downstream of the developer discharge port 22h in the developer transport direction. It is formed to extend to the side.

  According to this configuration, when the magnetic roller 52 rotates from the developer supply port 22g side toward the developer discharge port 22h side, the developer is lifted upward in the vicinity of the developer supply port 22g in the developer container 22. The bulk of the developer at the developer discharge port 22h disposed on the upper side of the developer supply port 22g becomes sufficiently high, and the excess developer can be reliably discharged from the developer discharge port 22h.

  In the first and second embodiments, the replenishing and conveying member is configured by the magnetic roller 52. However, the present invention is not limited to this, and the conveying screw 51 disposed in the conveying pipe 53 is connected to the developer supply port 22g. The supply screw 51 may be configured by the conveyance screw 51. Further, the replenishment conveying member may be configured to have paddle-shaped blades around the rotation axis. In these cases, similarly to the first and second embodiments, it is possible to prevent the developer just supplied from the developer supply port 22g from being discharged from the developer discharge port 22h.

  In the first and second embodiments, the developer supply port 22g and the developer discharge port 22h are arranged on the upstream side of the first transport path 22c. However, the present invention is not limited to this, and the development is performed. The agent supply port 22g and the developer discharge port 22h may be arranged downstream or in the center of the first conveyance path 22c, or may be arranged in the second conveyance path 22d. In these cases, the same effects as those of the first and second embodiments are obtained.

  In the first and second embodiments, an example is shown in which the present invention is applied to a monochrome copying machine. However, the present invention is not limited to this, and may be applied to a developing device for each color of a color copying machine or a color printer. .

  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 11 Photosensitive body (image carrier)
14 Developing Device 22 Developing Container 22c First Conveying Path 22g Developer Supply Port 22h Developer Discharge Port 22p Side Wall 23 First Stirring Member (Stirring Member)
24 Second stirring member 27 Developing roller 51 Conveying screw (replenishment conveying member)
52 Magnetic roller (replenishment conveying member)
53 Conveying pipe 56 Discharge screw 58 Discharge pipe

Claims (6)

A developer container for containing the developer; a stirring member that is rotatably supported by the developer container and agitates and conveys the developer in the developer container; and a developer replenishing port that supplies the developer into the developer container; A replenishment conveying member disposed opposite to the developer replenishing port from the outside of the developing container and transporting the developer into the developing container from the developer replenishing port, and excess developer in the developing container is discharged A developer discharge port,
The developer discharge port is formed in a side wall in the longitudinal direction of the developer container, the developer supply port is formed near the lower side of the developer discharge port, and the stirring member is connected to the developer from the developer discharge port side. The developing device, wherein the developing device rotates toward the agent replenishing port, and the replenishment conveying member rotates in the same direction as the stirring member.   The developing device according to claim 1, wherein the replenishing and conveying member includes a magnetic roller that generates a magnetic field on a surface thereof.   The gap between the upper edge of the developer supply port and the magnetic roller is substantially equal to the height of the magnetic brush formed on the magnetic roller, and the gap between the lower edge of the developer supply port and the magnetic roller is the magnetic field. The developing device according to claim 2, wherein the developing device is larger than a height of the brush.   4. The developing device according to claim 1, wherein the developer replenishing port is disposed downstream of the stirring member in a developer transport direction with respect to the developer discharge port. 5. .   The developing device according to claim 1, wherein the developer supply port is disposed at the same position in the developer transport direction of the stirring member with respect to the developer discharge port. .   An image forming apparatus on which the developing device according to claim 1 is mounted.

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