JP2007086311A - Developing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stabilize discharge of developer from a discharge port without increasing the scale of a developing device. <P>SOLUTION: Developer is conveyed by a second stir conveyance auger 40. Excessive developer overflows from the discharge port 64 into a storage chamber 62. The shaft 42 of the second stir conveyance auger 40 is provided with a discharge promoting blade 48 of a plate shape in its axial direction. Both ends of the discharge promoting blade 48 are joined to spiral parts 44 and counter spiral parts 46. Before developer is conveyed to a diaphragm part N by the corresponding spiral part 44, the developer is conveyed in the direction of arrow S by the discharge promoting blade 48, so that the flow of developer is dispersed. This prevents the developer from rising in the diaphragm N. Consequently, a shutter 60 is not closed by the rise of developer and thus the developer is stably smoothly discharged from a discharging port 64. In addition, this eliminates the need to increase the height of the discharging opening 64 or opening/closing stroke of the shutter 60, and avoids an increase in the scale of the developing device. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a developing device.

  In the trickle system, a developer in which toner and carrier are mixed in advance is accommodated in a developer cartridge, and toner is supplied from the developer cartridge to the developing device, and at the same time, a new carrier is also supplied little by little. At this time, since the amount of developer in the developing device increases, when a certain amount or more accumulates, the excess developer is discharged out of the developing device. Therefore, the developer is stabilized without deterioration, that is, the charge amount does not fall below a predetermined value.

  In such a trickle system, a configuration has been proposed in which surplus developer is discharged from a discharge port of a developing device by using the rotational operation of a rotary developing device as disclosed in Patent Document 1. (See Patent Document 1).

  However, in the configuration of Patent Document 1, when the developer does not rotate, such as when printing is performed in the single color mode, the excess developer cannot be discharged, so the developer is filled with the developer. For this reason, problems such as torque increase and concentration decrease are likely to occur. In addition, productivity is lowered when the rotation operation is frequently performed to discharge the excess developer.

  Therefore, as in Patent Document 2, it has a storage chamber for temporarily storing excess developer discharged from the discharge port, and when the developer is rotated and moved to the discharge position, the developer is discharged from the storage chamber. A configuration has been proposed in which a collection unit collects a road. (See Patent Document 2).

  However, the configuration of Patent Document 2 requires a discharge path, a collection unit, and the like in addition to the developing unit, which increases the size and cost of the apparatus.

  Patent Document 3 proposes a configuration in which the developer is retained in a part of the agitating / conveying auger, and excess developer is discharged from an upper discharge port where the developer water level has risen. ing. (See Patent Document 3).

  However, in the configuration of Patent Document 3, surplus developer discharged from the discharge port at the top of the developing device is difficult to move in the horizontal direction. For this reason, if there is no transport member that transports the developer to the recovery unit, a large amount of developer cannot be stored (the storage performance is limited). Accordingly, when the developer does not rotate, such as when printing in the single color mode, the excess developer cannot be discharged, and the developer is filled with the developer. For this reason, problems such as torque increase and concentration decrease are likely to occur. Further, if the rotation operation is frequently performed to discharge the developer, the productivity is lowered. Alternatively, providing a transport member that transports the developer to the collection unit increases the cost.

To solve the problems up to now, a discharge port is provided so that the upper part opens between the side of the developer housing and the agitating and conveying auger. In order to prevent the developer from being excessively discharged and to be discharged excessively, a configuration has been proposed in which a shutter that opens and closes by its own weight with rotation is provided at the discharge port. (For example, refer to Patent Document 4).
JP 09-218575 A JP-A-10-142888 JP 2000-112229 A JP 2003-114578 A

  However, in the configuration described in Japanese Patent Application Laid-Open No. 2003-114578 of Patent Document 4, in order to discharge smoothly according to the fluctuation of the developer level, the shutter overflows the developer and the developer in the storage chamber. It is necessary not to disturb the accumulation of water. Therefore, it is necessary to secure a sufficient stroke for the opening / closing operation of the shutter. Furthermore, it is necessary to make the outlet sufficiently high and wide enough.

  Thus, smoothly discharging the developer led to an increase in the size of the developing device. Further, since the opening / closing operation range of the shutter is increased, unintended developer (developer that should not be discharged) may be discharged from the discharge port with the rotation operation.

  The present invention has been made to solve the above problem, and aims to stabilize the discharge of the developer from the discharge port without increasing the size.

  In order to achieve the above object, a rotary developing device according to claim 1 contains a developer containing at least toner and a carrier and develops a latent image formed on an image carrier and is held by the rotary member. In the developing unit that is sequentially opposed to the developing position of the photosensitive member by the rotation of the rotating body, the developing unit is provided on the developing unit, and is formed on the outer periphery of the conveying shaft and the conveying shaft. A spiral spiral portion that transports the developer in the axial direction, and a spiral counter spiral portion that is formed on the transport shaft on the downstream side in the transport direction from the end of the spiral portion and is opposite to the spiral portion. A discharge port that is provided on a wall surface of the developing device facing a boundary portion between the spiral portion and the counter spiral portion, and allows the developer to overflow from the developing device; and Provided between the storage chamber for storing the discharged developer, the boundary and the discharge port, and opened and closed at the developing position by opening and closing the discharge port by its own weight as the rotating body rotates. A plate-like shutter that is in a state, and a plate-like discharge promotion blade having an angle different from that of the spiral portion is formed on the outer periphery of the conveyance shaft, and one end portion of the discharge promotion blade is formed on the spiral portion. It is characterized in that it is on the downstream side in the transport direction from the end portion, and the other end portion of the discharge promoting blade is on the upstream side in the transport direction from the end portion of the spiral portion.

  In the developing device according to the first aspect, the developer conveyed by the spiral portion overflows from the discharge port, so that the water level of the developer is kept constant.

  Now, at the boundary portion between the spiral portion and the counter spiral portion, a throttle portion is formed in which the width between the tip portion of the spiral portion and the tip portion of the counter spiral portion becomes gradually narrower. In the aperture portion, the developer conveyed in the spiral portion rises. Then, due to the protrusion of the developer, the shutter is closed, and the discharge of the developer from the discharge port is hindered. Therefore, it is necessary to increase the height of the discharge port or increase the opening / closing stroke of the shutter so that the shutter does not close even when the developer rises.

  Therefore, a plate-like discharge promoting blade having an angle different from that of the spiral portion is provided on the transport shaft. In addition, the arrangement of the discharge promotion blades is such that one end portion is on the downstream side in the transport direction from the end portion of the spiral portion, and the other end portion is on the upstream side in the transport direction from the end portion of the spiral portion.

  When such a discharge promoting blade is provided, the developer transported by the spiral portion is moved in a direction different from the developer transport direction by the spiral portion by the discharge promoting blade before the developer transported by the spiral portion. Sent. That is, the developer flow is dispersed before being sent to the throttle unit. For this reason, the developer is hardly raised.

  Accordingly, since the shutter does not close due to the rising of the developer, the developer is stably and smoothly discharged. Further, it is not necessary to increase the height of the discharge port or increase the opening / closing stroke of the shutter so that the developer does not rise and close the shutter. Therefore, the developing device is not increased in size. Further, excessive discharge of the developer due to an unnecessarily large opening / closing stroke of the shutter can be prevented.

  According to a second aspect of the present invention, there is provided the developing device according to the first aspect, wherein the one end portion of the discharge promotion blade is located downstream in the transport direction from the end portion of the counter spiral portion.

  In the developing device according to the second aspect, since the one end portion of the discharge promotion blade is located on the downstream side in the transport direction from the end portion of the counter spiral portion, the developer flow is further dispersed. Accordingly, the occurrence of the bulge at the throttle portion is further suppressed, so that the developer is discharged more stably and smoothly.

  According to a third aspect of the present invention, there is provided the developing device according to the first or second aspect, wherein both ends of the discharge promotion blade are in contact with the spiral portion and the counter spiral portion. It is said.

  In the developing device according to the third aspect, since the discharge promoting blades are in contact with the spiral portion and the counter spiral portion at both ends, the developer flow sent by the spiral portion is more reliably dispersed. Therefore, the bulge at the throttle portion can be more reliably suppressed, so that the developer is discharged more stably and smoothly.

  The developing device according to claim 4 is the configuration according to any one of claims 1 to 3, wherein the end of the shutter upstream in the transport direction has a reduced cross section in the transport direction. It is characterized by.

  In the developing device according to claim 4, since the cross section of the end portion on the upstream side in the conveyance direction of the shutter is reduced in the conveyance direction, the conveyed developer is blocked by the end portion of the shutter and is retained. It is smoothly transported without being discharged and discharged from the discharge port.

  According to a fifth aspect of the present invention, in the configuration according to the fourth aspect, the end portion on the upstream side in the transport direction of the shutter includes a stepped portion.

  The developing device according to claim 5 is smoothly transported by the stepped portion at the upstream end in the transport direction of the shutter without being blocked and stayed, and is discharged from the discharge port. The

  According to a sixth aspect of the present invention, in the configuration according to the fourth aspect, the end portion on the upstream side in the transport direction of the shutter has a slope.

  In the developing device according to claim 6, the developer that has been transported is blocked and retained smoothly by the slope of the end on the upstream side in the transport direction of the shutter, and is discharged from the discharge port. .

  According to a seventh aspect of the present invention, there is provided the developing device according to any one of the first to sixth aspects, further comprising a contact member that contacts the front shutter as the transport shaft rotates. It is said.

  In the developing device according to the seventh aspect, as the conveyance shaft rotates, the contact member comes into contact with the shutter, and the shutter swings. Therefore, the developer staying between the shutter and the discharge port is forcibly discharged.

  The developing device according to an eighth aspect is the configuration according to the seventh aspect, wherein the contact member is provided in a range where the counter spiral portion is formed.

  In the developing device according to the eighth aspect, the developer is very small in the range where the counter spiral portion is formed. Therefore, it is preferable to provide the contact member in a range where such a developer is very small because it does not affect the conveyance of the developer.

  A developing device according to a ninth aspect is characterized in that, in the configuration according to any one of the first to eighth aspects, the spiral portion has an outer diameter on the upstream side in the transport direction.

  In the developing device according to the ninth aspect, the outer diameter of the spiral portion on the upstream side in the transport direction is increased, the developer transport capability is increased, and the discharge from the discharge port is made smoother.

  The developing device according to claim 10 is the configuration according to any one of claims 1 to 9, wherein the shutter is attached so as to apply a force in a direction to open the shutter at the developing position. It is characterized by having a weight that is provided.

  According to a tenth aspect of the present invention, the shutter includes a weight attached so as to apply a force in a direction to open the shutter at the developing position.

  Therefore, the shutter is surely opened. Even when a force that closes the shutter is applied, the open state is maintained. Therefore, the developer can be discharged more reliably and smoothly.

  According to an eleventh aspect of the present invention, in the configuration according to the tenth aspect, the weight is connected to the shutter by a connecting member, and the weight is arranged in the storage chamber.

  In the developing device according to an eleventh aspect, the weight connected to the shutter by the connecting member is arranged in the storage chamber. Therefore, the weight does not hinder the developer discharge. Moreover, since the space of the storage chamber is effectively used, the size does not increase even if a weight is attached to the shutter.

  As described above, according to the present invention, the discharge of the developer from the discharge port can be stabilized without increasing the size.

  The developing device according to the present invention will be described below. Note that illustrations and descriptions of those not directly related to the essence of the present invention are omitted.

  FIG. 1 is a configuration diagram illustrating a main part of an image forming apparatus provided with a rotary developing device 10 including developing units 12 for respective colors. The image forming apparatus forms an image on a recording medium such as a recording sheet by an electrophotographic process. As a developing method, a so-called two-component developing method is adopted. The trickle method is adopted.

  In the trickle system, a developer in which toner and carrier are mixed in advance is stored in the developer cartridge 80, and the toner and carrier are simultaneously supplied from the developer cartridge 80 to the developing device 12, and the excess developer is removed. In this method, the developer is discharged from the developing device 12 to prevent the deterioration of the developer.

  As shown in FIG. 1, in the image forming apparatus, a drum-type electrophotographic photosensitive member as an image carrier, that is, a photosensitive drum 102 is supported to be rotatable in the direction of arrow R1 in the drawing. The surface of the photosensitive drum 102 that rotates in the direction of the arrow R1 is charged by charging means (not shown). The charged photosensitive drum 102 is exposed by irradiating a laser beam or the like according to image information by an exposure unit (not shown), thereby forming an electrostatic latent image on the photosensitive drum 102. The electrostatic latent image is developed by the developing device 12 of the rotary developing device 10 to form a toner image on the photosensitive drum 102.

  The rotary developing device 10 includes a rotating body 11 having a cross-shaped cross section. The rotator 11 holds a developing unit 12K for black, a developing unit 12Y for yellow, a developing unit 12M for magenta, and a developing unit 12C for cyan. The rotating shaft of the rotating body 11 can be freely rotated in the direction of the arrow R2 by driving means (not shown) such as a motor and a gear mechanism.

  In the following, when distinguishing each color, any of Y, M, C, and K is added after the symbol, and when it is not necessary to distinguish each color, Y, M, C, and K are omitted.

  When a black toner image is formed on the photosensitive drum 102, the rotating body 11 is rotated, and the black developing device 12K is disposed at the developing position P1 (see FIG. 2) close to the photosensitive drum 102. To develop. Similarly, when forming a yellow toner image, the rotating body 11 is rotated by approximately 90 ° in the direction of the arrow R2, and the yellow developing device 12Y is disposed at the developing position P1 for development. Similarly, when forming magenta and cyan toner images, the rotating body 11 is further rotated in the direction of the arrow R2 by about 90 °, and the developing devices 12M and 12C are arranged at the developing position P1 for development.

  In this way, the respective color toner images are sequentially formed on the photosensitive drum 102 and transferred to an intermediate transfer member (not shown) each time. Each color toner is superimposed on the intermediate transfer member to form a full-color toner image, and the full-color toner image on the intermediate transfer member is collectively transferred to a recording sheet (not shown).

  As shown in FIG. 2, the position where the developing device 12 develops on the photosensitive drum 102 is the development position P1. A position rotated 90 degrees from the developing position P1 in the direction of the arrow R2 is a position P2. Similarly, a position rotated 90 degrees from the position P2 is a position P3, and a position rotated 90 degrees from the position P3 is a position P4. The position rotated 90 degrees from the position P4 is the development position P1. Note that FIG. 2 is a simplified and schematic view.

  Next, the developing device 12 will be described. Note that the drawing of the developing device 12 alone shows the developing device 12 in the state of the developing position P1 (see FIG. 2).

  As shown in FIG. 3, the developing device 12 is divided into a first chamber 20, a second chamber 22, and a third chamber 24. The first chamber 20 and the second chamber 22, and the second chamber 22 and the third chamber 24 communicate with each other. A developer cartridge 26 communicates with the third chamber 24. The first chamber 20, the second chamber 22, and the third chamber 24 are filled with a developer composed of toner and a carrier supplied from the developer cartridge 26.

  The first chamber 20 is provided with a developing roll 28 and a first stirring / conveying auger 30. The second chamber 22 is provided with a second stirring / conveying auger 40. The third chamber 24 includes a supply auger 50. In addition, each axis rotates with an axis perpendicular to the drawing as a rotation axis. In other words, as shown in FIG. 4, the rotating rod-shaped developing roll 28, the first stirring / transporting auger 30, the second stirring / transporting auger 40, and the replenishing auger 50 are arranged in parallel.

  The developing roll 28 is at a position facing the photosensitive drum 102 at the developing position P1. (See FIG. 2). As shown in FIG. 3, the developing roll 28 is rotatably supported on the side wall of the housing 13 and is rotated by a gear mechanism (not shown). The developing roll 28 is a magnet roller that encloses a magnet in a sleeve. Therefore, the developing roll 28 attracts the carrier contained in the developer by magnetic force to form a magnetic brush, and the toner is attracted to the carrier. Then, a layer of the developer is formed on the developing roll 28 by the layer regulating member 29.

  As shown in FIGS. 3 and 4, a first agitating / conveying auger 30 and a second agitating / conveying auger 40 are arranged in parallel with the developing roll 28, and are pivotally supported on the lateral side wall of the housing 13. A gear mechanism (not shown) is provided at the ends of the shafts 32 and 42 of the first agitation transport auger 30 and the second agitation transport auger 40 so as to rotate in the same direction as the developing roll 28.

  A spiral portion 34 is formed on the outer periphery of the shaft 32 of the first stirring / conveying auger 30. The spiral portion 34 has a spiral shape. Similarly, a spiral portion 44 is formed on the outer periphery of the shaft 42 of the second stirring / conveying auger 40. The spiral portion 44 has a spiral shape inclined in the opposite direction to the spiral portion 34.

  Accordingly, when the first stirring / conveying auger 30 and the second stirring / conveying auger 40 are rotated with the rotation of the developing roll 28, the first stirring / conveying auger 30 stirs the developer while conveying the developer in the direction of arrow A, The developer is supplied to. The second agitating / conveying auger 40 agitates the developer in the direction of arrow B (the direction opposite to arrow A).

  The casing 13 is provided with a partition plate 14 that partitions the first agitation transport auger 30 and the second agitation transport auger 40 in the longitudinal direction, that is, the first chamber 20 and the second chamber 22. Circulating ports 14A and 14B are formed at both ends in the longitudinal direction of the partition plate 14, respectively. Therefore, the developer stirred and transported by the first stirring and transporting auger 30 is transported to the second chamber 22 through the circulation port 14A, and the developer stirred and transported by the second stirring and transporting auger 40 passes through the circulation port 14B. Then, it is conveyed to the first chamber 20. That is, the developer circulates around the partition plate 14.

  In addition, counter spiral portions 36 and 46, which are reversely wound from the spiral portions 34 and 44, are provided at the end portions of the first agitating / conveying auger 30 and the second agitating / conveying auger 40 on the developer conveying direction side. .

  The counter spiral portions 36 and 46 are narrower than the pitch of the spiral portions 34 and 44, and the inclination angle is smaller than that of the spiral portions 34 and 44. Therefore, the developer transport capability is lower than that of the spiral portions 34 and 44. In addition, the spiral part 34 of the 1st stirring conveyance auger 30 and the 2nd stirring conveyance auger 40 spiral part 44 have substantially the same conveyance capability.

  As described above, by providing the counter spiral portions 36 and 46 at both ends, the developer is not pressed against the lateral side wall of the housing 13, and at the boundary between the spiral portions 34 and 44 and the counter spiral portions 36 and 46. Developer stagnates. And since it is discharged | emitted smoothly from the circulation ports 14A and 14B of both ends, a developer circulates smoothly between the 1st chamber 20 and the 2nd chamber 22 on the boundary of the partition plate 36. FIG.

  Now, as shown in FIG. 6, the shaft 42 of the second stirring / conveying auger 40 is formed with a plate-like discharge promoting blade 48 which stands in the normal direction and is long in the axial direction. Both ends of the discharge promotion blade 48 are joined to the spiral portion 44 and the counter spiral portion 46. The height of the discharge promotion blade 48 is substantially the same as that of the spiral portion 44.

  Further, a protrusion 49 is formed on the shaft 42 between the counter spiral portions 46. The protrusion 49 hits a shutter 60 described later with the rotation of the second stirring / conveying auger 40.

  Although not clearly illustrated, the outer diameter of the three windings 46L (see FIG. 4) on the upstream end side of the spiral portion 44 of the second agitating / conveying auger 40 is slightly increased to increase the developer conveying force. It is increasing.

  As shown in FIG. 4, a replenishment auger 50 is pivotally supported on the lateral side wall in parallel with the second agitation transport auger 40. Further, a partition plate 16 is formed between the replenishing auger 50 and the second agitating / conveying auger 40.

  As shown in FIG. 3, a developer cartridge 80 is attached to the top of the replenishing auger 50, that is, to the top of the third chamber 24.

  As shown in FIG. 7, the developer cartridge 80 has a cylindrical shape, and the inside is divided into a storage chamber 82 and a recovery chamber 84. Inside the accommodation chamber 82 is a coil spring-like conveying member 99, and the developer is replenished from the replenishing port 86 to the third chamber 24 by the rotational movement of the conveying member 99. (See FIGS. 3 and 4).

  As shown in FIG. 4, the replenished developer is conveyed by the replenishment auger 50 and replenished to the second chamber 22 from the supply port 16 </ b> A formed in the partition plate 16. Further, according to the image density at the time of image formation, a control unit (not shown) rotates the supply auger 50 in the third chamber 24 to supply the developer to the second chamber 22.

  As shown in FIGS. 4, 5, and 16, the third chamber 24 extends up to the downstream end in the transport direction (arrow B direction) of the spiral portion 44 of the second agitating and transporting auger 40. The first chamber 20 and the second chamber 22 are shorter. The shortened portion serves as a storage chamber 62.

  As shown in FIG. 8, the upper portion of the storage chamber 62 communicates with the recovery chamber 84 (see FIG. 7) of the developer cartridge 80.

  As shown in FIG. 6, the wall facing the boundary between the spiral portion 44 and the counter spiral portion 46 of the second agitating / conveying auger 40, that is, between the storage chamber 62 (see FIG. 5) and the second chamber 22. A discharge port 64 is formed in the partition wall. Note that the upper position of the discharge port 64 is substantially the same as the upper portion of the second agitating / conveying auger 40.

  Now, as shown in FIGS. 6, 8, and 9, a plate-like shutter 60 is provided between the discharge port 64 and the second stirring / conveying auger 40. The shutter 60 rotates about the upper part (the upper part in the state of the development position P1) as the rotation center. Then, the discharge port 64 is opened and closed by its own weight by the rotation of the rotating body 11 (change in the action direction of gravity). At the development position P1, the shutter 60 is in an open state. Further, the shutter 60 hits a stopper 68 (see FIG. 9), and thus opens and stops to a predetermined angle.

  Further, as shown in FIG. 10, the surface 60A on the upstream side in the conveyance direction (arrow B direction) of the shutter 60 shown in FIG. 6 has a wedge shape that is pointed toward the conveyance direction (arrow B direction). It is a slope.

  As shown in FIG. 9, a wire 72 is joined to the shutter 60 on the surface opposite to the second agitating / conveying auger 40, and a weight 70 is attached to the tip of the wire 72. In other drawings, the wire 72 and the weight 70 may be omitted.

  Next, the opening / closing operation of the shutter 60 accompanying the rotation of the rotating body 11 (change in the action direction of gravity) and the discharge of the excess developer from the discharge port 64 will be described.

  As shown in FIG. 2, the shutter 60 is open at the development position P1. Therefore, if the developer level becomes higher than a predetermined height, the excess developer overflows from the discharge port 64 and is discharged. The developer discharged from the discharge port 64 is stored in the storage chamber 62.

  When rotated 90 degrees to position P2, the shutter 60 closes the discharge port 64 by its own weight. Therefore, the developer is not discharged from the discharge port 64 to the storage chamber 62.

  When rotated further 90 ° to position P 3, the developer in the storage chamber 62 is sent to the collection chamber 84 of the developer cartridge 80 by gravity.

  When it further rotates 90 ° to position P4, the shutter 60 is opened by its own weight. However, since the discharge port 64 is positioned above, the developer is not discharged from the discharge port 64 to the storage chamber 62.

  Further, when the image is further rotated by 90 °, the original developing position P1 is obtained.

  Next, the overflow of the excess developer from the discharge port 64 at the development position P1, which is an effect of the present invention, will be described.

  As shown in FIGS. 5, 6, and 16, the developer is sent in the direction of arrow B by the second agitating / conveying auger 40, and the excess developer is discharged in the flow as shown by arrow M. 64 overflows into the storage chamber 62.

  Note that the three windings 46L (see FIG. 4) on the upstream end side of the spiral portion 44 of the second agitating / conveying auger 40 have a slightly larger outer diameter and a higher developer conveying force. It is discharged from the outlet 64.

  Further, as shown in FIG. 10, a surface 60A on the upstream side in the transport direction of the shutter 60 shown in FIG. 6 has a slope that is pointed toward the transport direction and has a wedge shape. Accordingly, as indicated by an arrow M in FIG. 10, the developer hits the upstream end of the shutter 60 in the transport direction and is smoothly blocked without being retained and discharged from the discharge port 64.

  It should be noted that the upstream end of the shutter 60 in the transport direction may have a configuration in which the cross section gradually decreases in the transport direction so that the developer is smoothly transported without stagnation. For example, like the shutter 61 of FIG. 11, the structure provided with the step part 61A in the edge part of the conveyance direction upstream may be sufficient.

  At the boundary between the spiral portion 44 and the counter spiral portion 46, the narrowed portion N in which the width between the upstream tip portion of the spiral portion 44 and the downstream tip portion of the counter spiral portion 46 gradually decreases. (The part surrounded by a dotted circle in the figure) is formed. In the aperture portion N, the developer conveyed by the spiral portion 44 rises. Then, due to the protrusion of the developer, the shutter 60 is pushed and closed, and the discharge of the developer is hindered.

  Therefore, in the present embodiment, the shaft 42 of the second stirring / conveying auger 40 is provided with a plate-like discharge promotion blade 48 that is long in the axial direction (a direction orthogonal to the rotation direction R3). Then, both ends of the discharge promotion blade 48 are joined to the spiral portion 44 and the counter spiral portion 46.

  When such a discharge promotion blade 48 is provided, the developer conveyed in the axial direction (arrow B direction) by the spiral portion 44 as shown in FIGS. 5, 6, 13 (B), 16 and the like. Since the developer is sent in a direction (arrow S direction) different from the arrow B direction by the discharge promotion blade 48 before being sent to the narrowed portion N, the developer flow is dispersed. A dotted arrow C in the drawing schematically illustrates the flow of the developer that advances between the spiral portions 44 as the second stirring / conveying auger 40 rotates. As can be seen from the arrow C, the discharge promoting blades 48 disperse (change) the flow of the developer before being sent to the narrowed portion N. In this way, since the developer flow is dispersed (changed), the developer hardly rises at the narrowed portion N.

  Therefore, since the shutter 60 is not closed by the rise of the developer, the developer is discharged from the discharge port 64 stably and smoothly. Further, since it is not necessary to increase the height of the discharge port 64 or increase the opening / closing stroke of the shutter 60, the developing device does not increase in size. Furthermore, since the opening / closing stroke of the shutter 60 is not increased more than necessary, unnecessary developer is not discharged with the rotation operation. (The developer is not excessively discharged).

  Further, the developer that has been conveyed by the discharge promotion blade 48 is sent in the direction of the arrow S, that is, toward the wall surface on which the discharge port 64 is formed, so that the developer is more easily discharged from the discharge port 64.

  Further, as shown in FIGS. 6 and 9, as the second agitating / conveying auger 40 rotates, the protrusion 49 comes into contact with the shutter 60, and the shutter 60 swings. Therefore, the developer staying between the shutter 60 and the discharge port 64 is forcibly discharged from the discharge port 64.

  The protrusion 49 is provided in a range where the counter spiral part 46 with very little developer is formed. Therefore, it is preferable because the protrusion 49 does not cause a problem such as blocking the flow of the developer.

  Further, as shown in FIG. 9, a wire 72 is joined to the surface of the shutter 60 opposite to the second agitating / conveying auger 40, and a weight 70 is attached to the tip of the wire 72. The weight 70 is in the storage chamber 62.

  Now, when there is no weight 70, as shown to FIG. 12 (A), the shutter 60 falls vertically. However, as shown in FIG. 12B, when the weight 70 is attached, a force is applied in a direction in which the weight 70 pushes the lower portion, so that the shutter 60 is inclined to the opposite side of the weight 70.

  Therefore, in FIG. 9, the shutter 60 is stopped at a predetermined angle by the stopper 68, so that the angle itself does not change, but the direction in which the weight 70 pushes the lower part to the open side (the second stirring and conveying auger 40 side). Power is added to. Therefore, even when a force is applied in the direction in which the shutter 60 is closed, the state in which the shutter 60 is opened can be more reliably maintained.

  Further, since the weight 70 is disposed in the storage chamber 62, the weight 70 does not hinder the discharge of the developer. Further, since the space of the storage chamber 62 is effectively used, the developing device 12 is not enlarged even if the weight 70 is attached to the shutter 60.

  The discharge promotion blade 48 is not limited to the configuration of the above embodiment.

  For example, as shown in FIG. 13, the upstream end 48 </ b> A in the transport direction (arrow B direction) of the discharge promoting blade 48 and the end T <b> 1 of the spiral portion 44 are set to 0 ° as shown in FIG. 13. Then, what is necessary is just to provide so that it may join within T2 which is 360 degree | times in the arrow Q direction (carrying direction upstream direction). This is because even if the developer conveyance direction is dispersed by the blade 600 at a position exceeding 360 ° indicated by the dotted line in the drawing, the developer rises at the narrowed portion N by the developer conveyed after the dispersion. In other words, in the blade 600, the developer does not flow as indicated by the dotted arrow C shown in FIG. Therefore, there is little effect at this position.

  Further, as shown in FIG. 14, although the effect is slightly reduced, the gaps may be opened without joining the ends 160 </ b> A and B of the discharge promotion blade 160 to the spiral portion 44 and the counter spiral portion 46. .

  Alternatively, as shown in FIG. 15, the effect is further reduced, but the upstream end 162 </ b> A in the transport direction (arrow B direction) of the discharge promotion blade 162 is the end of the spiral portion 44 and the end of the counter spiral portion 46. It may be located in a range between.

  Further, for example, the discharge promotion blade 48 has a plate shape that is long in the same direction as the rotation axis direction of the second agitating / conveying auger 40. good. However, if the angle is the same as that of the spiral portion 44, the developer is not sent in a direction different from that of the spiral portion 44, so that there is no effect.

1 is a diagram illustrating a schematic configuration of a rotary developing device including a developing device according to an embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing which shows typically the image development apparatus provided with the developing device of embodiment of this invention, and demonstrates opening / closing operation | movement of a shutter accompanying discharge | rotation of a rotary body, and discharge from the discharge port of the excess developer. is there. It is sectional drawing which looked at the inside of the developing device from the horizontal direction. It is sectional drawing which looked at the inside of a developing device from the upper part. It is the enlarged view to which the discharge opening vicinity of FIG. 4 was expanded. FIG. 6 is a perspective view of the vicinity of a discharge port inside the developing device. FIG. 3 is a diagram schematically illustrating a developer cartridge. FIG. 5 is a cross-sectional view including an enlarged view portion of FIG. 4, as seen from the lateral direction inside the developing device. It is sectional drawing which shows the discharge port vicinity inside a developing device. It is the schematic diagram which looked at the shutter from the upper part. It is the schematic diagram which looked at the shutter of the other example from the upper part. (A) shows a shutter when there is no weight, and (B) shows a shutter when there is a weight. The positional relationship between the counter unit and the discharge promoting blades will be described. (A) is a perspective view of the vicinity of the discharge port, and (B) is a schematic view of the second stirring and conveying auger as viewed from above. It is the schematic diagram which looked at the 2nd stirring conveyance auger from the upper side which shows typically the discharge promotion blade | wing of another example. It is the schematic diagram which looked at the 2nd stirring conveyance auger from the upper side which shows typically the discharge promotion blade | wing of another example. FIG. 6 is a perspective view of the vicinity of a discharge port inside the developing device.

Explanation of symbols

10 Rotating developer
11 Rotating body
12 Developer
40 Second agitation transport auger
42 Shaft (conveying axis)
44 Spiral part
46 Counter spiral section
48 discharge promotion blade
60 shutters
62 Reservoir
64 outlet
70 weights
72 wire (connection member)
102 Photosensitive drum (image carrier)

Claims (11)

A developing device that stores a developer containing at least a toner and a carrier and develops a latent image formed on the image bearing member, and is held by the rotating member and is sequentially opposed to the developing position of the photosensitive member by the rotation of the rotating member. In
A spiral shaft provided in the developing device, formed on the outer periphery of the transport shaft, and transports the developer in the axial direction along with the rotation of the transport shaft, and an end of the spiral section A spiral counter spiral portion formed on the transport shaft on the downstream side in the transport direction and having a spiral direction opposite to the spiral portion;
A discharge port provided on a wall surface of the developing device facing a boundary portion between the spiral portion and the counter spiral portion, and allowing an overflow of the developer from the developing device;
A storage chamber for storing the developer discharged from the discharge port;
A plate-like shutter that is provided between the boundary portion and the discharge port, opens and closes the discharge port by its own weight as the rotating body rotates, and is opened at the development position;
With
A plate-shaped discharge promotion blade having an angle different from that of the spiral portion is formed on the outer periphery of the transport shaft, and one end portion of the discharge promotion blade is located on the downstream side in the transport direction from the end portion of the spiral portion. The developing device according to claim 1, wherein the other end portion of the accelerating blade is located upstream of the end portion of the spiral portion in the transport direction.   The developing device according to claim 1, wherein the one end portion of the discharge promoting blade is located on the downstream side in the transport direction from the end portion of the counter spiral portion.   The developing device according to claim 1, wherein both ends of the discharge promotion blade are in contact with the spiral portion and the counter spiral portion.   4. The developing device according to claim 1, wherein an end of the shutter on the upstream side in the conveyance direction has a smaller cross section in the conveyance direction. 5.   The developing device according to claim 4, wherein the end portion on the upstream side in the conveyance direction of the shutter includes a stepped portion.   The developing device according to claim 4, wherein the end portion on the upstream side in the conveyance direction of the shutter has a slope.   The developing device according to claim 1, wherein a contact member that contacts the front shutter is provided along with the rotation of the conveyance shaft.   The developing device according to claim 7, wherein the contact member is provided in a range where the counter spiral portion is formed.   9. The developing device according to claim 1, wherein the spiral portion has a larger outer diameter on the upstream side in the conveyance direction. 10.   The developing device according to claim 1, wherein the shutter includes a weight attached so as to apply a force in a direction of opening the shutter at the developing position.   The developing device according to claim 10, wherein the weight is connected to the shutter by a connecting member, and the weight is disposed in the storage chamber.

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