JP2013113894A - Developing device, and image forming apparatus including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device that suppresses variation in the amount of toner supplied from a toner container in association with decrease in developer in a retaining unit even when the amount of toner in the toner container changes.SOLUTION: A first conveyance capability suppressing unit 26 forms a retaining unit 27 at a position facing a toner supply port 25. Depending on the amount of toner in the retaining unit 27, the amount of toner flowing into a developing housing 210 from a toner container 30 is adjusted. The inflow amount of supply toner easily varies with the amount of the supply toner remaining in the toner container 30. Even when the toner container 30 is replaced and a large amount of toner tends to easily flow into the developing housing 210, the upstream side in a conveyance direction of the toner supply port 25 is sealed by an upstream-side retaining unit 29 formed by a suppressing paddle 28, and thereby excessive inflow of the supply toner is suppressed.

Description

  The present invention relates to a developing device suitably mounted on an image forming apparatus such as a copying machine or a printer, and an image forming apparatus including the developing device.

  Conventionally, a developing device as described in Patent Document 1 is known. The developing device includes a developing housing having a developing roller and a stirring screw, and a toner container for replenishing toner that is detachably attached to the developing housing. A toner discharge port that can be opened and closed is provided at the bottom of the toner container, and a toner supply port is provided at a position corresponding to the toner discharge port in the development housing. When the toner container is mounted on the developing housing and the toner discharge port and the toner replenishing port are opened, the toner in the toner container is supplied to a predetermined circulation conveyance path formed in the developing housing.

  The circulation conveyance path includes an outward conveyance path corresponding to the toner replenishing port and a backward conveyance path corresponding to the developing roller. Each circulation conveyance path is equipped with a stirring screw having spiral blades arranged around the rotation axis. The toner is circulated and conveyed between the forward conveyance path and the backward conveyance path by these stirring screws.

  In the developing device of Patent Document 1 having such a configuration, a transport capability suppressing unit configured to locally decrease the transport capability downstream of the toner supply port of the stirring screw provided in the forward transport path. Is provided. By such a conveyance capability suppression unit, a toner retention portion is formed in the vicinity of the toner supply port on the upstream side of the conveyance capability suppression unit. When the amount of toner in the staying portion is large, the toner in the staying portion blocks the toner supply port. When the amount of toner in the staying portion is small, a gap is generated between the toner supply port and the toner staying portion, and the toner flows into the developing housing from the toner container side. Thus, the toner replenishment amount to be replenished from the toner container to the developing housing is adjusted according to the toner amount staying in the staying portion.

JP-A-2005-346116

  In the developing device described in Patent Document 1, when a toner container with a small amount of remaining toner is replaced with a new toner container containing a large amount of replenished toner, a large amount of replenished toner in the new toner container causes a toner in a staying portion. Will be pressed from above. As a result, the toner in the staying portion cannot block the toner supply port, and a large amount of supply toner flows into the developing housing. In this case, the old toner previously stored in the developing device is mixed with a large amount of new toner replenished from the toner container at once, resulting in a problem that the chargeability of the toner becomes unstable. .

  The present invention has been made in order to solve the above-described problems. In the developing device in which the replenishment developer is replenished from the replenishment developer accommodating portion as the developer in the staying portion decreases, the replenishment development is performed. It is an object of the present invention to provide a developing device in which the amount of developer replenishment to the housing side hardly changes even when the amount of developer in the agent container changes rapidly.

  A developing device according to an aspect of the present invention includes a housing that houses a developer, a replenishment developer housing portion that is detachable from the housing and houses a replenishment developer that is replenished to the housing, A developer transport path disposed in the housing and transporting the developer; and disposed in the housing facing the developer transport path, and supplying the replenishment developer from the replenishment developer container. A developer receiving port that is received in the developer conveying path; and the developer receiving port that is disposed in the developer conveying path and that passes through a position facing the developer conveying path in one conveying direction. A developer transport unit that transports the developer, and the developer transport unit that is disposed downstream of the developer receiving port of the developer transport unit in the transport direction, and partially suppresses the developer transport capability of the developer transport unit. By doing so, the replenishment developer is placed at a position where the developer receiving port faces. A first conveyance capacity suppressing unit that forms a developer retention unit that adjusts the amount of the toner, and the developer conveyance unit upstream of the developer receiving port of the developer conveyance unit, and the development of the developer conveyance unit A second conveyance capacity suppression unit that forms an upstream developer retention part upstream of the developer receiving port and in the conveyance direction upstream by partially suppressing the conveyance capacity of the developer. To do.

  According to this configuration, the first transport capability suppressing unit forms the developer retaining portion in the developer transport path and at a position facing the developer receiving port. When the amount of developer in the developer transport path is large, the developer retaining portion seals the opposing developer receiving port. For this reason, it is difficult for the replenishment developer to flow from the replenishment developer container to the housing side. On the other hand, when the amount of developer in the developer transport path is small, a gap is formed between the developer retaining portion and the developer receiving port, and the replenishment developer flows into the housing side from the replenishment developer accommodating portion. The inflow amount of the replenishment developer is likely to change according to the amount of developer in the replenishment developer container. According to the above configuration, even when the replenishment developer accommodating portion is replaced and a large amount of the replenishment developer easily flows into the developer conveyance path side, the second conveyance ability suppression unit conveys the developer at the inlet. An upstream developer retaining portion is formed on the upstream side in the direction. The upstream developer retaining portion partially seals the upstream side in the transport direction of the developer receiving port in the developer transport path. For this reason, excessive inflow of the replenishment developer to the housing side is suppressed.

  In the above configuration, it is preferable that the developer transport unit includes a rotation shaft and screw blades formed around the rotation shaft, and the developer is transported by rotation of the screw blades.

  According to this configuration, the developer is transported in the developer transport path by the screw blades formed around the rotation axis. The screw blades have a force for extruding the developer in the rotational radius direction in addition to the conveyance direction. For this reason, in the developer retention part formed by the first conveyance capacity suppressing part, the developer can easily seal the developer receiving port by the rotational force of the screw blade.

  Said structure WHEREIN: It is preferable that the said 1st conveyance capability suppression part is formed by missing the said screw blade | wing.

  According to this configuration, the developer retaining portion is formed by a portion where the screw blade is missing. For this reason, compared with the case where the screw blades are arranged in the first conveyance capacity suppressing portion, the formation of the developer retention portion is less dependent on the rotation speed of the developer conveyance member. Therefore, even when the developer conveying member is rotationally driven at a plurality of rotational speeds, the developer retaining portion is formed, and the replenishment of the replenishment developer is stably adjusted.

  Said structure WHEREIN: It is preferable that the said 2nd conveyance capability suppression part is formed by attaching the plate-shaped member extended | stretched to the rotation radial direction of the said rotating shaft to the said rotating shaft or the said screw blade | wing.

  According to this configuration, the upstream developer retaining portion is formed on the upstream side of the developer receiving port by the rotation of the plate-like member. As a result, the upstream side of the developer receiving port in the developer conveyance path is easily sealed with the developer, and an excessive supply of replenishment developer is suppressed. Further, the rotating plate-like member can mechanically suppress the replenishment developer from entering the developer transport path upstream.

  Said structure WHEREIN: It is preferable that a said 2nd conveyance capability suppression part is formed when the outer diameter of the said screw blade is set small.

  According to this configuration, the developer conveyance performance is reduced corresponding to the portion where the outer diameter of the screw blade is small. For this reason, an upstream developer retaining portion is formed on the upstream side of the developer receiving port. As a result, the upstream side of the developer receiving port in the developer conveyance path is easily sealed with the developer, and an excessive supply of replenishment developer is suppressed.

  Said structure WHEREIN: It is preferable that the said 2nd conveyance capability suppression part is formed by missing the said screw blade | wing.

  According to this configuration, the upstream developer retaining portion is formed on the upstream side of the developer receiving port corresponding to the portion where the screw blade is missing. As a result, compared to the case where the screw blades are provided, the upstream side of the developer receiving port in the developer conveyance path is easily sealed with the developer, and an excessive supply of replenishment developer is suppressed.

  In addition, an image forming apparatus according to another aspect of the present invention includes an image carrier on which an electrostatic latent image is formed on a surface, and the electrostatic latent image is manifested in a developer image by the developer, And a developing device according to any one of the above.

  According to this configuration, even when the replenishment developer accommodating portion is replaced and a large amount of replenishment developer tends to flow into the developer conveyance path, the upstream developer stagnation formed by the second conveyance capacity suppression portion The portion partially seals the upstream side in the transport direction of the developer receiving port in the developer transport path. For this reason, an excessive flow of replenishment developer to the developer conveyance path is suppressed. As a result, a large amount of replenishment developer is prevented from being rapidly mixed into the developer in the developing device. Therefore, developer fogging caused by poor stirring of the developer is prevented.

  According to the present invention, in the developing device in which the replenishment developer is replenished from the replenishment developer accommodating portion, the amount of the developer in the replenishment developer accommodating portion changes rapidly as the developer in the developer retaining portion decreases. However, it is possible to provide a developing device in which the amount of developer replenishment to the housing is unlikely to change. In particular, even under conditions where the amount of developer in the replenishment developer accommodating portion increases rapidly, a large amount of replenishment developer does not flow into the housing, and image quality defects such as developer fog are suppressed.

1 is a schematic diagram illustrating an internal structure of an image forming apparatus according to an embodiment of the present invention. 1 is a plan view of a developing device according to an embodiment of the present invention. FIG. 3 is a cross-sectional view of a toner replenishing unit according to an embodiment of the present invention. It is a perspective view of a stirring screw concerning one embodiment of the present invention. It is a schematic diagram of toner replenishment according to an embodiment of the present invention. It is a schematic diagram of conventional volume supply type toner supply.

  A developing device according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view schematically showing a configuration of an image forming apparatus 1 including a developing device 20 according to an embodiment of the present invention. The image forming apparatus 1 includes an optical scanning device 11, a developing device 20, a toner container 30 (replenishment developer container), a charger 13, a photosensitive drum 14 (image carrier), a transfer roller 15, a fixing device 16, and a paper feed. A cassette 17 is provided.

  The photosensitive drum 14 is a cylindrical member, and an electrostatic latent image and a toner image are formed on the peripheral surface thereof. The photosensitive drum 14 receives a driving force from a motor (not shown) and rotates in the clockwise direction in FIG. The charger 13 charges the surface of the photosensitive drum 14 substantially uniformly.

  The optical scanning device 11 includes a light source such as a laser diode, a deflector, a scanning lens, an optical element, and the like. The optical scanning device 11 irradiates the peripheral surface (scanned surface) of the photosensitive drum 14 that is substantially uniformly charged by the charger 13 with a laser beam corresponding to the image data, thereby electrostatically charging the image data. A latent image is formed.

  The developing device 20 supplies toner to the peripheral surface of the photosensitive drum 14 on which the electrostatic latent image is formed to form a toner image. The developing device 20 includes a developing roller that carries toner and a stirring screw that stirs and conveys the toner. The toner image formed on the photosensitive drum 14 is transferred from the sheet feeding cassette 17 and transferred to the sheet conveyed through the conveyance path P. The developing device 20 is supplied with toner from a toner container 30. The developing device 20 will be described in detail later.

  The toner container 30 is a box-shaped member and stores toner therein. The toner container 30 supplies toner into the developing device 20. The toner container 30 is detachably disposed with respect to the developing device 20.

  A transfer roller 15 is disposed below the photosensitive drum 14 so as to face each other, and a transfer nip portion is formed by both. The transfer roller 15 is composed of a conductive rubber material or the like. The transfer roller 15 is applied with a transfer bias by a bias applying unit (not shown). The transfer roller 15 transfers the toner image formed on the photosensitive drum 14 onto the recording paper.

  The fixing device 16 includes a fixing roller 160 incorporating a heater and a pressure roller 161 provided at a position facing the fixing roller 160. The fixing device 16 fixes the toner image formed on the recording paper by heating and conveying the recording paper on which the toner image is formed.

<Description of developing device>
FIG. 2 is a plan view showing the internal structure of the developing device 20. The developing device 20 includes a developing housing 210 (housing) having a box shape elongated in one direction (the axial direction of the developing roller 21). The developing housing 210 has an internal space 220. In the internal space 220, the developing roller 21, the first stirring screw 23 (developer conveying unit), the second stirring screw 24, and the toner supply port 25 are disposed. In the case of the one-component development method, the internal space 220 is filled with toner as a developer. In the case of the two-component development method, a mixture of toner and a carrier made of a magnetic material is filled as a developer. The toner is agitated and conveyed in the internal space 220 and is sequentially supplied from the developing roller 21 to the photosensitive drum 14 in order to develop the electrostatic latent image.

  The developing roller 21 has a cylindrical shape that extends in the longitudinal direction of the developing housing 210 and has a sleeve portion that is rotationally driven on the outer periphery. In the case of the one-component development method, toner having a charge due to frictional charging adheres to the sleeve portion from the second conveying screw 24. In the case of the two-component development method, the magnetic carrier is attached to the sleeve surface from the second agitating screw 24 by the magnetic field formed by the magnetic pole fixedly arranged inside the sleeve together with the toner adhering by electrostatic force. Adhere to. The toner (developer) carried on the sleeve surface is conveyed to an opening (not shown) provided in the developing housing 210 and supplied to the opposing photosensitive drum 14.

  The internal space 220 of the developing housing 210 is covered with a top plate (not shown) and is partitioned into a first passage 221 and a second passage 222 that are long in the left-right direction by a partition plate 22 extending in the left-right direction. The partition plate 22 is shorter than the width in the left-right direction of the developing housing 210, and an upstream communication portion 223 and a downstream communication portion 224 that respectively connect the first passage 221 and the second passage 222 to the left end and the right end of the partition plate 22. Is provided. As a result, a circulation path (developer transport path) reaching the first passage 221, the upstream communication portion 223, the second passage 222, and the downstream communication portion 224 is formed in the internal space 220. The toner is conveyed in the clockwise direction in FIG.

  The toner replenishing port 25 (developer receiving port) is an opening formed in the top plate, and is disposed above the vicinity of the left end of the first passage 221 (FIG. 2). The toner replenishing port 25 is disposed so as to face the above-described circulation path, and has a function of receiving replenished toner (supplied developer) replenished from the toner container 30 into the internal space 220.

  The first stirring screw 23 is disposed in the first passage 221. The first agitating screw 23 includes a first rotating shaft 23a (rotating shaft) and a first spiral blade 23b (screw blade) protruding in a spiral shape on the circumference of the first rotating shaft 23a. The first agitating screw 23 is driven to rotate about the first rotation shaft 23a (arrow R2), thereby conveying the toner in the direction of arrow D1 in FIG. The first agitation screw 23 conveys the developer so that the toner replenishing port 25 passes through a position facing the first passage 221. Thus, the first stirring screw 23 has a function of mixing new toner flowing from the toner replenishing port 25 and toner transported through the first passage 221 and delivering the mixed toner to the second passage 222 side. Have. A first paddle 23c is disposed downstream of the first stirring screw 23 in the toner conveyance direction (D1 direction). The first paddle 23c is a plate-like member disposed on the first rotating shaft 23a. The first paddle 23 c is rotated together with the first rotation shaft 23 a and delivers the toner from the first passage 221 to the second passage 222.

  The second stirring screw 24 is disposed in the first passage 222. The second agitating screw 24 includes a second rotating shaft 24a and a second spiral blade 24b protruding in a spiral shape on the circumference of the second rotating shaft 24a. The second agitating screw 24 is driven to rotate around the second rotation shaft 24a (arrow R1), thereby conveying the toner in the direction of arrow D2 in FIG. The second agitating screw 24 transports toner in the second passage 222 and supplies the toner to the developing roller 21. A second paddle 24c is disposed downstream of the second stirring screw 24 in the toner conveyance direction (D2 direction). The second paddle 24c is a plate-like member disposed on the second rotation shaft 24a. The second paddle 24 c is rotated together with the second rotation shaft 24 a and delivers the toner from the second passage 222 to the first passage 221.

  The toner container 30 is disposed above the toner supply port 25 of the developing housing 210. The toner container 30 includes a toner transport path 30 a through which toner is transported, a toner transport member 321, and a toner discharge port 33. In the toner container 30, the longitudinal direction of the toner container 30 (the direction in which the toner conveyance path 30 a is formed) is orthogonal to the longitudinal direction of the developing device 20 (the developer conveyance direction of the first stirring screw 23, the direction of the arrow D <b> 1). The developing device 20 is assembled so as to be positioned in the direction.

  The toner discharge port 33 is disposed at the bottom of the toner container 30 corresponding to the toner supply port 25 of the developing device 20. The toner conveying member 321 has a shaft portion and a blade portion that rotates around the shaft portion (see FIG. 3), and conveys the replenishment toner in the toner conveying path 30 a toward the toner discharge port 33. The toner dropped from the toner discharge port 33 is supplied to the developing device 20 through the toner supply port 25.

<About staying part>
Next, the flow of toner newly supplied from the toner supply port 25 will be described. FIG. 3 is a cross-sectional view of the vicinity of the toner supply port 25 provided in the developing device 20 and the toner discharge port 33 provided in the toner container 30. In FIG. 3, for the sake of explanation, the arrangement of the toner container 30 is shown rotated 90 degrees in the horizontal direction. Actually, the toner conveying member 321 in the toner container 30 extends toward the front of the sheet, and the first stirring screw 23 and the toner conveying member 321 in the toner container 30 are in a positional relationship orthogonal to each other. ing.

  The replenishment toner T2 supplied from the toner discharge port 33 of the toner container 30 falls into the first passage 221 and is mixed with the existing toner T1, and is conveyed by the first agitating screw 23 in the direction of arrow D1. At this time, the toners T1 and T2 are stirred and charged.

  The first agitating screw 23 includes a first conveyance capacity suppressing unit 26 that partially suppresses the developer conveyance performance downstream of the toner supply port 25 in the toner conveyance direction. In this embodiment, the 1st conveyance capability suppression part 26 is formed by missing the stirring blade of the 1st stirring screw 23 (refer FIG. 4). Therefore, the first transport capability suppressing portion corresponds to a portion where only the first rotating shaft 23a is partially disposed. In this case, the 1st conveyance capability suppression part 26 does not have the developer conveyance performance of the 1st rotating shaft 23a direction. Accordingly, the toner transported from the upstream side of the first transport capability suppression unit 26 in the first passage 221 starts to stay in the first transport capability suppression unit 26. The toner stays on the upstream side of the first conveyance capacity suppressing unit 26 and accumulates until the toner supply port 25 faces the first passage 221. As a result, a developer retention portion 27 (developer retention portion) is formed in the vicinity of the inlet of the toner supply port 25.

  Note that, when the first stirring screw 23 of the developing device 20 is controlled at different rotational speeds according to the operating conditions of the image forming apparatus 1, as in the present embodiment, the first transport capability suppression unit 26 is It is preferable not to have the stirring blade 23b and to be configured only in the region of the first rotating shaft 23a. In this case, since the toner conveyance performance is suppressed without depending on the rotation speed of the first stirring screw 23, the staying portion 27 is stably formed.

  When the replenishment toner T2 is replenished from the toner replenishing port 25 and the amount of toner in the internal space 220 increases, the toner staying in the staying portion 27 closes (seals) the toner replenishing port 25, and more toner is added. Suppress supply. Thereafter, when the toner in the internal space 220 is consumed from the developing roller 21 and the toner staying in the staying portion 27 is reduced, the toner that has blocked the toner replenishing port 25 is reduced, and the space between the staying portion 27 and the toner replenishing port 25 is reduced. There is a gap in As a result, the replenishment toner T2 flows into the internal space 220 from the toner replenishment port 25 again. Thus, in the present embodiment, a volume replenishment type toner replenishment format is adopted in which the amount of replenishment toner received is adjusted as the amount of toner remaining in the retention portion 27 decreases.

  In such a volume replenishment type toner replenishment format, when the toner amount of the replenishment toner T2 accommodated in the toner container 30 changes abruptly, the replenishment toner T2 suddenly flows into the internal space 220 of the developing housing 210. There are things to do. In particular, this phenomenon occurs remarkably when the remaining amount of toner in the toner container 30 attached to the developing device 20 decreases and the toner container 30 is replaced with a new toner container 30 by the user. Hereinafter, this phenomenon will be described with reference to FIG.

  5A and 5B are cross-sectional views of the first passage 221 in the developing housing 220 as viewed from the horizontal direction. In either case, toner flows from the downstream communication portion 224 at the right end of the first passage 221 in the drawing. The toner conveyed in the first passage 221 by the first stirring screw 23 is sent to the second passage 222 side by the first paddle 23c at the left end of the first passage 221 in the figure. 5A and 5B, a toner container 30 (not shown) is disposed above the toner supply port 25 disposed on the downstream side of the first passage 221. FIGS. 5A and 5B show how the toner distribution in the first passage 221 changes depending on the amount of toner in the toner container 30.

  FIG. 5A shows the state of the first passage 221 in a state where the amount of toner in the toner container 30 is small. FIG. 5B shows a state after the toner container 30 is replaced with a new one from the state of FIG. In the case of FIG. 5A, since the amount of the replenishment toner T2 that can fall from the toner discharge port 33 is small, the pressure that the replenishment toner T2 applies downward to the staying portion 27 is small (arrow Y21). For this reason, the pressure required for the staying portion 27 to seal the toner supply port 25 from below is also small. Therefore, the replenishment toner T2 and the toner in the staying portion 27 are balanced in a state where they are pressed with a small pressure, and the toner replenishing port 25 is sealed. At this time, the distribution of the toner T1 in the first passage 221 includes a staying portion 27 that covers the toner supply port 25, and a first upstream portion 100b that is distributed with an inclined surface immediately upstream of the toner supply port 25. Furthermore, the second upstream portion 100c having a draft surface that is stabilized substantially horizontally on the upstream side.

  Here, the amount of toner in the toner container 30 decreases, and the user is warned by a display unit (not shown) provided in the image forming apparatus 1. The user removes the old toner container 30 and attaches a new toner container 30 to the developing device 20 at an appropriate time. Since the new toner container 30 contains a large amount of toner, the replenishment toner T2 that is about to fall from the toner discharge port 33 toward the toner replenishment port 25 is rapidly increased by the replacement of the toner container 30. . For this reason, in the toner replenishing port 25, the pressure applied downward by the replenishing toner T2 to the staying portion 27 increases (arrow Y22). At the toner replenishing port 25, the pressure applied downward by the replenishing toner T2 to the staying portion 27 exceeds the pressure applied by the staying portion 27 upward to the replenishing toner T2. As a result, the replenishment toner T2 enters the first upstream portion 100b side where the pressure (sealing force) against the toner replenishment port 25 is weak in the first passage 221 (arrow 100d). This toner intrusion is a sudden inflow of toner out of the adjustment range, corresponding to the toner consumed from the developing roller 21, the developer in the staying portion 27 decreases, and the replenishment that flows in from the toner replenishing port 25. It is different from the toner flow.

  After the toner container 30 is replaced, when the developing device 20 is controlled and the first stirring screw 23 and the second stirring screw 24 rotate, the toner distribution in the internal space 220 changes due to the inflow of the replenishing toner T2. . That is, as shown in FIG. 5B, when the amount of toner in the internal space 220 increases abruptly, the amount of toner retained by the first transport capability suppression unit 26 also increases. For this reason, the staying part 27 extends to the upstream side of the toner supply port 25, and the second staying part 27b is formed. Then, the first upstream portion 100b and the second upstream portion 100c also move to the upstream side in the toner transport direction (arrow D1 direction), respectively, and the third upstream portion 100e and the fourth upstream portion 100f are formed. Since the second staying portion 27b closes the toner replenishing port 25 from the upstream side and the downstream side with more toner than the staying portion 27, the entry of the replenishing toner T2 that has flowed in immediately after the replacement of the toner container 30 is finally suppressed. It is done.

  As described above, when the toner container 30 is replaced with a new one having a small amount of toner accommodated therein and a new one having a large amount of toner, the pressure at which the replenishing toner T2 acts on the toner replenishing port 25 is changed, The replenishment toner T2 suddenly flows into the first passage 221. In this case, since the replenishment toner T2 and the toner T1 accommodated in the first passage 221 cannot be stirred and mixed with each other in a short time, the toner charge amount varies. The toner having uneven charge amount causes toner fog on the photosensitive drum 14 after development.

<Upstream side retention part>
As described above, in order to solve the problem that a large amount of toner suddenly flows into the developing device 20 due to a change in the amount of toner in the toner container 30, in this embodiment, toner supply to the first passage 221 is performed. The first agitation screw 23 includes a suppression paddle 28 (second conveyance capability suppression unit) at a position upstream of the mouth 25 in the toner conveyance direction (arrow D1 direction) (FIGS. 2 and 4).

  The restraining paddle 28 is a plate-like rib member extending between two first spiral blades 23b adjacent in the direction of arrow D1 and extending in the rotational radius direction of the first rotating shaft 23a. The suppression paddle 28 is rotated in the direction of the arrow R2 as the first stirring screw 23 is rotated, and transports the toner T1 transported in the first passage 221 in the R2 direction. For this reason, in the vicinity of the suppression paddle 28, the conveyance performance of the toner T1 in the direction of the arrow D1 is suppressed, and the toner T1 stays. Due to the staying toner T <b> 1, an upstream staying portion 29 is formed in the first passage 221 immediately upstream of the toner supply port 25.

  With reference to FIG. 6, the state of toner distribution of the developing device 20 provided with the suppression paddle 28 of the present embodiment will be described. FIG. 6 is a cross-sectional view of the first passage 221 in the developing housing 220 as seen from the horizontal direction, similarly to FIG. FIG. 6A shows a state of the internal space 220 when the toner amount in the toner container 30 is small. FIG. 6B shows a state after the toner container 30 is replaced with a new one from the state of FIG. In FIG. 6A, in the first passage 221, a staying portion 27 is formed by the first transport capability suppressing portion 26 at a position facing the toner supply port 25. Further, immediately upstream of the toner supply port 25, an upstream side retention portion 29 is formed by the suppression paddle 28.

  The upstream staying part 29 stays on the upstream side of the toner supply port 25 so as to block the first passage 221. When the amount of toner in the toner container 30 is small, the pressure applied downward by the replenishing toner T2 to the staying portion 27 at the toner replenishing port 25 is small (arrow Y23). In this case, on the first passage 221 side, the staying portion 27 and the upstream staying portion 29 block around the toner supply port 25 and apply pressure upward to the supply toner T2. For this reason, the replenishment toner T2 does not flow into the internal space 220 and stops near the toner replenishment port 25.

  On the other hand, when the toner container 30 is replaced with a new one, the amount of toner accommodated in the toner container 30 is large, so that the pressure that the replenishing toner T2 applies downward to the staying portion 27 at the toner replenishing port 25 increases. . Even in this case, in the present embodiment, the staying portion 27 and the upstream staying portion 29 apply pressure upward to the replenishing toner T2 at the toner replenishing port 25. There is no sudden flow into the first passage 221 (FIG. 6B). In particular, when the suppression paddle 28 is not provided, the replenishment toner T2 is likely to enter, and the upstream side of the toner replenishment port 25 is sealed by the upstream side retention portion 29. Therefore, the replenishment toner T2 suddenly enters the first passage 221. Inflow is suppressed.

  Thus, the restraining paddle 28 forms the upstream side retention portion 29, and the upstream side retention portion 29 has a function of sealing the upstream side of the toner supply port 25. Further, the restraining paddle 28 is disposed at the outermost position in the radial direction in the first spiral blade 23b. For this reason, on the upstream side of the toner replenishing port 25, the rotating suppression paddle 28 forms a barrier on the cross section orthogonal to the first rotation shaft 23a and in a region close to the inner peripheral surface of the developing housing 210. To do. For this reason, after replacement of the toner container 30, the supply toner T <b> 2 is further suppressed from flowing into the upstream side of the toner supply port 25.

  When the toner in the internal space 220 is consumed from the developing roller 21 to the photosensitive drum 14 side and the developer in the staying portion 27 and the upstream staying portion 29 is reduced, the replenishment toner T2 is transferred to the internal space 220 (the first space). 1 passage 221).

  As described above, in the developing device 20 according to the present embodiment, a rapid inflow of toner into the developing housing 210 that is likely to occur after the replacement of the toner container 30 is suppressed. For this reason, insufficient stirring is unlikely to occur between the toner that flows in abruptly and the toner in the developing housing 210, and the toner fog on the photosensitive drum 14 is suppressed.

  The developing device according to the embodiment of the present invention has been described above. However, the present invention is not limited to this, and for example, the following modified embodiment can be adopted.

  (1) In the above embodiment, the portion where the stirring blades of the first stirring screw 23 are missing is the first transport capability suppressing unit 26. In addition to this, the first spiral blade 23b of the first stirring screw 23 The bar member may be arranged in the peripheral portion in parallel with the rotation shaft, and the portion where the bar member is attached may be the first conveyance capacity suppressing unit 26. The stick member attached to the stirring blade suppresses the toner transport capability, and the toner stays in the first passage 221.

  (2) In the above-described embodiment, the suppression paddle 28 forms the upstream staying portion 29 as the second conveyance capability suppression portion. However, the present invention is not limited to this. For example, the second conveyance capacity suppressing unit may be formed by partially disposing only the first rotating shaft 23a, that is, by deleting the first spiral blade 23b. In this case, the toner conveyance capability in the direction of the first rotation shaft 23a (the direction of the arrow D1) is reduced, and similarly, the upstream side retention portion 29 is formed. Moreover, the 2nd conveyance capability suppression part may be formed partially by setting the outer diameter of the 1st spiral blade 23b small.

20 Developing device 210 Developing housing (housing)
23 1st stirring screw (developer conveying part)
23a First rotating shaft (rotating shaft)
23b 1st spiral blade (screw blade)
23c 1st paddle 24 2nd stirring screw 24a 2nd rotating shaft 24b 2nd spiral blade 24c 2nd paddle 25 Toner supply port (developer receiving port)
26 First Conveyance Capacity Suppression Unit 27 Retention Unit (Developer Retention Unit)
28 Suppression paddle (2nd conveyance capacity control part)
29 Upstream side retention section 30 Toner container (replenishment developer storage section)
33 Toner outlet

Claims (7)

A housing for containing the developer;
A replenishment developer accommodating portion that is removably attached to the housing and houses a replenishment developer replenished to the housing;
A developer transport path disposed in the housing and transporting the developer;
A developer receiving port disposed in the housing so as to face the developer conveyance path, and receiving the replenishment developer from the replenishment developer accommodating portion into the developer conveyance path;
A developer transport unit that is disposed in the developer transport path and transports the developer in one transport direction so that the developer receiving port passes through a position facing the developer transport path;
The developer inlet is opposed to the developer inlet by being partially disposed in the downstream of the developer inlet of the developer carrier and partially suppressing the developer carrying capacity of the developer carrier. A first conveyance capacity suppression unit that forms a developer retention portion that adjusts the amount of the replenishment developer received at a position to be
The developer transport unit is disposed on the upstream side in the transport direction from the developer receiving port, and partially suppresses the developer transport capability of the developer transport unit. A second conveyance capacity suppression unit that forms an upstream developer retention part on the upstream side in the conveyance direction;
A developing device comprising:   2. The developer transport unit according to claim 1, wherein the developer transport unit includes a rotation shaft and screw blades formed around the rotation shaft, and the developer is transported by rotation of the screw blades. Development device.   The developing device according to claim 2, wherein the first conveyance capacity suppressing unit is formed by missing the screw blade.   The said 2nd conveyance capability suppression part is formed when the plate-shaped member extended | stretched in the rotation radial direction of the said rotating shaft is attached to the said rotating shaft or the said screw blade | wing. The developing device according to 1.   4. The developing device according to claim 2, wherein the second conveyance capacity suppression unit is formed by setting an outer diameter of the screw blade to be small. 5.   4. The developing device according to claim 2, wherein the second conveyance capacity suppression unit is formed by missing the screw blade. 5. An image carrier on which an electrostatic latent image is formed on the surface, and the electrostatic latent image is visualized into a developer image by the developer;
A developing device according to any one of claims 1 to 6,
An image forming apparatus comprising:

Images