JP2005321470A - Developing unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance developer stirring ability by preventing developer transported while it is stirred by a stirring member from passing through a retaining part formed by a transporting load member such as a straightening vane without retaining there. <P>SOLUTION: In the developing unit 18Y, the straightening vane 161 is formed on the rotary shaft 162 of a spiral auger 90, and a projecting part 150A is formed to be opposed to the straightening vane 161 in a housing 150. Therefore, the developer detouring to keep away from the straightening vane 161 and flowing to a downstream side is dammed by the projecting part 150A and retains. Thus, the developer is completely stirred. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  In the present invention, a plurality of stirring members each having a spiral stirring blade formed on the rotation shaft convey the two-component developer in the housing while stirring along the developing roll, and the developing roll is moved by the stirring member. The present invention relates to a developing device for developing an image bearing member with a stirred developer.

  Among developing devices provided in image forming apparatuses such as printers and copiers, in a developing device employing a two-component developing method using a two-component developer composed of toner and a carrier, a stirring member is used in the developing device housing. The developer is circulated with stirring and supplied to the developing roll.

  By the way, with the recent demand for downsizing of the image forming apparatus, it is necessary to shorten the developer transport distance in the developer housing. However, because the developer agitation is reduced due to the deterioration of the developer fluidity associated with the reduction in the particle size of the toner and carrier for improving the image quality, the developer is sufficiently agitated in a short transport distance. It has become difficult to do.

  For this reason, a mechanism for increasing the stirring ability of the developer has been devised (for example, see Patent Document 1). In this patent document 1, a baffle plate is provided in some places on the rotating shaft of the stirring member to reduce the developer conveying ability in some places, and the developer is retained in the part and stirred, thereby increasing the stirring ability. .

However, since the developer tries to flow around the rectifying plate by avoiding it, a part of the developer passes around the rectifying plate without being retained in the staying portion by the rectifying plate and is sufficiently stirred. There has been a problem that the toner is supplied to the developing roll without any trouble.
JP 2001-183899 A

  The present invention has been made in consideration of the above fact, and the developer conveyed while being stirred by the stirring member passes through this staying part without staying in the staying part by the transport load member such as a current plate. To prevent that.

  The developing device according to claim 1, wherein a plurality of stirring members each having a spiral stirring blade formed on a rotation shaft conveys the developer in the housing while stirring along the developing roll, and the developing roll A developing device for developing the image carrier with the developer stirred by the stirring member, the transport load member protruding from the rotating shaft and receiving a transport load from the developer, and from the housing toward the transport load member And a projecting member for retaining the developer around the transport load member.

  In the developing device according to claim 1, the developer in the housing is conveyed while being stirred along the developing roll by a plurality of stirring members, and the developing roll is configured to remove the image carrier with the developer stirred by the stirring member. develop.

  Here, in addition to the spiral stirring blade, a conveying load member protrudes from the rotating shaft of the agitating member, and this conveying load member receives the conveying load from the developer conveyed by the agitating member and develops the developer. To stay around.

  A protruding member protrudes from the housing toward the conveyance load member, and the developer stays around the conveyance load member even if the developer tries to pass around the conveyance load member.

  Therefore, the developer conveyed by the agitating member can be sufficiently agitated at the staying portion formed by the conveying load member and the protruding member, and image defects associated with poor agitation of the developer can be prevented.

  A developing device according to a second aspect is the developing device according to the first aspect, wherein the conveying load member and the protruding member are provided at a distance of one pitch or more from a toner supply port to the housing. And

  According to a second aspect of the present invention, the conveying load member and the protruding member are provided apart from the toner supply port to the housing by a distance corresponding to one pitch of the stirring blade. For this reason, the developer crest generated by the conveyance load member and the projecting member is blocked by the stirring blade for one pitch, so that this developer clog does not block the toner supply port.

  The developing device according to claim 3 is the developing according to claim 1 or 2, wherein a plurality of the transport load members are provided, and the projecting member is used as the transport load member on the toner supply port side to the housing. It is characterized by being provided opposite to.

  According to a third aspect of the present invention, a plurality of transport load members are provided, and the protruding member is provided to face the transport load member on the toner supply port side. Here, the upstream side in the transport direction has a lower transport capability than the downstream side in the transport direction, so that it is easier to retain the developer in the stay portion than in the case where the protruding member is provided on the downstream side in the transport direction.

  In addition, the height of the developer crest that can be formed on the upstream side in the transport direction is increased, so that a trough that is formed between the crest and the crest that is formed on the downstream side is deepened, and the developer does not easily get over the crest of the developer on the downstream side. Therefore, the developer tends to stay in the staying portion on the downstream side.

  Since the present invention is configured as described above, it is possible to prevent the developer conveyed while being stirred by the stirring member from passing through the staying portion without staying in the staying portion due to the transport load member such as a current plate.

  An embodiment of the present invention will be described below with reference to the drawings.

  1 and 2 show a four-cycle full-color printer 10 as an image forming apparatus. Inside the printer 10, a photosensitive drum 12 as an image carrier is rotatably disposed at an upper right part slightly from the center. As this photosensitive drum 12, for example, a drum made of a conductive cylinder having a diameter of about 47 mm and having a surface coated with a photosensitive layer made of OPC or the like is used. It is rotationally driven at a process speed of about 150 mm / sec.

  The surface of the photosensitive drum 12 is charged to a predetermined potential by a charging roll 14 disposed almost directly below the photosensitive drum 12, and then an ROS 16 (Raster Output Scanner) serving as an exposure device disposed below the charging roll 14. ), Image exposure with a laser beam (LB) is performed, and an electrostatic latent image corresponding to image information is formed.

  The electrostatic latent image formed on the photosensitive drum 12 passes through the developing units 18Y, 18M, 18C, and 18K for each color of yellow (Y), magenta (M), cyan (C), and black (K) in the circumferential direction. The toner is developed by a rotary developing device 18 arranged along the toner image to be a toner image of a predetermined color.

  At this time, charging, exposure, and development processes are repeated a predetermined number of times on the surface of the photosensitive drum 12 in accordance with the color of the image to be formed. In the rotary developing device 18, the corresponding color developing devices 18 </ b> Y, 18 </ b> M, 18 </ b> C, and 18 </ b> K move to a developing position facing the photosensitive drum 12.

  For example, when a full-color image is formed, the charging, exposing, and developing processes are performed on the surface of the photosensitive drum 12 in yellow (Y), magenta (M), cyan (C), and black (K) colors. The toner image corresponding to each color of yellow (Y), magenta (M), cyan (C), and black (K) is sequentially formed on the surface of the photosensitive drum 12. .

  When the toner image is formed, for example, in the case of A4 size, one image is formed by rotating the photosensitive drum 12 three times. That is, a toner image corresponding to each color of yellow (Y), magenta (M), cyan (C), and black (K) is formed on the surface of the photosensitive drum 12 every time the photosensitive drum 12 rotates three times. Is done.

  The yellow (Y), magenta (M), cyan (C), and black (K) toner images sequentially formed on the photosensitive drum 12 are transferred onto the outer periphery of the photosensitive drum 12 as an intermediate transfer member. At the primary transfer position where the belt 20 is wound, the primary transfer is performed by the primary transfer roll 22 while being superimposed on the intermediate transfer belt 20.

  The yellow (Y), magenta (M), cyan (C), and black (K) toner images transferred in multiple onto the intermediate transfer belt 20 are recorded on a recording sheet 24 fed at a predetermined timing. Secondary transfer is collectively performed by the secondary transfer roll 26.

  On the other hand, the recording paper 24 is fed from a paper feed cassette 28 disposed at the bottom of the printer 10 by a pickup roll 30 and is fed one by one by a feed roll 32 and a retard roll 34 to be registered. The roller 36 is conveyed to the secondary transfer position of the intermediate transfer belt 20 in synchronization with the toner image transferred onto the intermediate transfer belt 20.

  The intermediate transfer belt 20 includes a wrap-in roll 38 that specifies the wrap position of the intermediate transfer belt 20 on the upstream side in the rotational direction of the photosensitive drum 12 and a toner image formed on the photosensitive drum 12 as an intermediate transfer belt. A primary transfer roll 22 that is transferred onto the intermediate transfer belt 20, a wrap-out roll 40 that specifies the wrap position of the intermediate transfer belt 20 on the downstream side of the wrap position, and a backup that contacts the secondary transfer roll 26 via the intermediate transfer belt 20. The roll 42, the first cleaning backup roll 46 facing the cleaning device 44 of the intermediate transfer belt 20, and the second cleaning backup roll 48 are stretched with a predetermined tension and have a predetermined process speed (about 150 mm / sec), for example, as the photosensitive drum 12 rotates. It is driven Te.

  Here, in order to reduce the size of the printer 10, the intermediate transfer belt 20 is configured such that the cross-sectional shape on which the intermediate transfer belt 20 is stretched becomes a flat and elongated substantially trapezoidal shape.

  The intermediate transfer belt 20 includes a photosensitive drum 12, a charging roll 14, an intermediate transfer belt 20, a plurality of rolls 22, 38, 40, 42, 46, and 48 that stretch the intermediate transfer belt 20, and an intermediate transfer belt. The image forming unit 52 is constituted by a cleaning device 44 for 20 and a cleaning device 78 for the photosensitive drum 12 described later, and is integrally provided.

  For this reason, the entire image forming unit 52 can be removed from the printer 10 by opening the upper cover 54 of the printer 10 and lifting the handle (not shown) provided on the upper portion of the image forming unit 52 by hand.

  On the other hand, the cleaning device 44 for the intermediate transfer belt 20 includes a scraper 58 disposed so as to come into contact with the surface of the intermediate transfer belt 20 stretched by the first cleaning backup roll 46, and a second cleaning backup roll 48. A cleaning brush 60 disposed so as to be in pressure contact with the surface of the stretched intermediate transfer belt 20, and residual toner and paper dust removed by the scraper 58 and the cleaning brush 60 are contained in the cleaning device 44. It has come to be collected.

  The cleaning device 44 is disposed so as to be able to swing counterclockwise in the drawing with the swing shaft 62 as the center, and until the secondary transfer of the final color toner image is completed, the intermediate transfer belt is provided. It is configured to retreat to a position separated from the surface of the surface 20 and to contact the surface of the intermediate transfer belt 20 when the secondary transfer of the final color toner image is completed.

  Further, the recording paper 24 onto which the toner image is transferred from the intermediate transfer belt 20 is conveyed to a fixing device 64, and the fixing device 64 fixes the toner image on the recording paper 24 with heat and pressure. In this case, the paper is discharged as it is onto a discharge tray 68 provided at the top of the printer 10 by a discharge roll 66.

  On the other hand, in the case of double-sided printing, the recording paper 24 on which the toner image is fixed by the fixing device 64 is not directly discharged onto the discharge tray 68 by the discharge roll 66, but the rear end of the recording paper 24 by the discharge roll 66. The paper discharge path 66 is reversed in a state where the section is held, and the conveyance path of the recording paper 24 is switched to the double-sided paper conveyance path 70, and the conveyance roll 72 disposed in the double-sided paper conveyance path 70 is used. Then, the recording paper 24 is conveyed again to the secondary transfer position of the intermediate transfer belt 20 with the front and back sides of the recording paper 24 reversed, and an image is formed on the back surface of the recording paper 24.

  Further, in the full color printer, a manual feed tray 74 can be attached to the side surface of the printer 10 so as to be freely opened and closed as an option. An arbitrary size and type of recording paper 24 placed on the manual feed tray 74 is fed by a paper feed roll 76, and the secondary transfer position of the intermediate transfer belt 20 via a transport roll 72 and a registration roll 36. Thus, it is possible to form an image on the recording paper 24 of any size and type.

  The surface of the photosensitive drum 12 after the toner image transfer process is completed is cleaned by the cleaning blade 80 of the cleaning device 78 disposed obliquely below the photosensitive drum 12 every time the photosensitive drum 12 rotates once. Residual toner is removed to prepare for the next image forming process.

  On the other hand, FIG. 3 and FIG. 4 show a rotary developing device 18. FIG. 3 shows a state where one developing device 18Y and a toner cartridge 82Y are mounted on the developing device 18 for convenience.

  The developing device 18 includes a rotary 39 that supports the developing devices 18Y, 18M, 18C, and 18K. The rotary 39 is provided with a cylindrical rotary shaft member 41. The rotary 39 is pivotally supported around the rotary shaft member 41 so as to be able to rotate counterclockwise (in the direction of arrow A). Further, a front flange member 43 is provided at the front end of the rotary shaft member 41 in the longitudinal direction, and a rear side is provided at the rear end of the rotary shaft member 41 in the longitudinal direction of the drawing. The flange member 45 is provided.

  The cylindrical space S formed by the rotary shaft member 41 and the flange members 43 and 45 is divided into four every 90 degrees by the partition member 47.

  In the space partitioned by the partition member 47, four developing devices 18Y, 18M, 18C, and 18K of yellow (Y), magenta (M), cyan (C), and black (K) are clockwise in the circumferential direction. Each is implemented along.

  These developing units 18Y, 18M, 18C, and 18K include yellow (Y), magenta (M), cyan (C), and black (K) toners corresponding to the developing units 18Y, 18M, 18C, and 18K. The cartridges 82Y, 82M, 82C, and 82K are mounted, respectively, and new toner is supplied from the corresponding toner cartridges 82Y, 82M, 82C, and 82K (see FIGS. 5 and 6).

  Here, the developing devices 18Y, 18M, 18C, and 18K and the toner cartridges 82Y, 82M, 82C, and 82K are all configured in the same manner, and therefore, here, the yellow (Y) developing device 18Y and the toner cartridge 82Y are taken as an example. I will explain.

  As shown in FIGS. 8 and 9, the housing 150 of the developing device 18 </ b> Y has a long box shape along the direction orthogonal to the recording sheet to be conveyed, and is substantially in the center in the width direction of the housing 150. The partition wall 152 is erected to partition the housing 150 into a space 154 and a space 156. Clearances 158 and 160 are provided between both ends of the partition wall 152 and the peripheral wall of the housing 150, and the space 154 and the space 156 communicate with each other.

  A spiral auger 90 is disposed in the space 154 along the longitudinal direction of the housing 150, and a spiral auger 92 is disposed in the space 156 in parallel with the spiral auger 90. The spiral augers 90 and 92 include a rotation shaft 162 and are rotatably supported on the peripheral wall of the housing 150.

  A spiral auger 90 is disposed in the space 154 along the longitudinal direction of the housing 150, and a spiral auger 92 is disposed in the space 156 in parallel with the spiral auger 90. The spiral augers 90 and 92 include a rotation shaft 162 and are rotatably supported on the peripheral wall of the housing 150. Gears 166 and 168 are fixed to end portions of the rotating shaft 162, respectively.

  In addition, forward spiral blades 164 formed in a spiral shape are provided around the rotation shaft 162 of the spiral augers 90 and 92 (described later), and rotational force from a motor (not shown) is transmitted to the gears 166 and 168. When the spiral augers 90 and 92 are rotated through the gears 166 and 168, the forward spiral blade 164 conveys the developer contained in the housing 150 in the direction of the arrow while being stirred.

  Further, on the end of the spiral augers 90 and 92 on the downstream side in the conveying direction, there are provided one or two spiral reverse spiral blades 188 directed in the direction opposite to the spiral direction of the forward spiral blade 164. The developer conveyed by the spiral blade 164 is pushed back in the reverse direction.

  The ends of the spiral augers 90 and 92 pass through the peripheral wall of the developing device 18Y, and the space between the rotating shaft 162 and the peripheral wall of the developing device 18Y is sealed by packing so that the developer in the housing 150 does not leak. However, if the developer conveying force is large, the developer in the developing device 18Y may leak to the outside.

  For this reason, by providing a reverse spiral blade 188 on the downstream side of the spiral augers 90 and 92 in the transport direction so as to push back the transported developer, the transport force of the developer at the ends of the spiral augers 90 and 92 is reduced. In order to prevent the developer from leaking outside.

  On the other hand, a developing roll 88 is disposed obliquely above the spiral auger 92 along the longitudinal direction of the housing 150, and is rotatably supported on the peripheral wall of the housing 150. A gear 89 is fixed to the end of the developing roll 88, and a rotational force from a motor (not shown) is transmitted to the gear 89 so that the developing roll 88 rotates through the gear 89.

  At this time, the developer conveyed to the space 156 by the spiral auger 90 through the gap 160 is conveyed in the space 156 in the direction of the arrow by the spiral auger 92 and is equally supplied to the developing roll 88. The layer thickness of the developer supplied to the surface of the developing roll 88 is regulated by a layer thickness regulating member 96 (see FIG. 4).

  Incidentally, the housing 150 is provided with a cover 170, and the cover 170 covers the space 154 and the upper part of the space 156. In this state, as shown in FIG. 4, a part of the developing roll 88 is exposed and can face the photosensitive drum 12.

  The developing roll 88 adsorbs the carrier contained in the developer with a magnetic force, forms a magnetic brush of the developer on the surface, and conveys the toner adsorbed on the carrier to a developing area facing the photosensitive drum 12. The electrostatic latent image formed on the photosensitive drum 12 is visualized by a developer magnetic brush composed of a carrier and toner formed on the surface of the developing roll 88.

  As shown in FIGS. 6 and 7, an arc receiving plate 172 curved in a substantially arc shape is provided on the outer surface of one end side of the cover 170. The arc receiving plate 172 has a supply port 174 for supplying toner in a toner cartridge 82Y, which will be described later, into the housing 150, and a discharge port for discharging excess developer exceeding a predetermined amount in the housing 150 into the toner cartridge 82Y. 176 is formed.

  Further, the arc receiving plate 172 is provided with a shutter plate 114 so as to be slidable along the circumferential direction of the arc receiving plate 172. The shutter plate 114 is formed with a communication port 178 capable of communicating with the discharge port 176, The developer in the housing 150 communicates with the discharge port 176 and is discharged into the toner cartridge 82Y.

  Here, in the shutter plate 114, the communication port 178 and the discharge port 176 are in communication with each other, and the developer in the housing 150 can be discharged into the toner cartridge 82Y. New toner can be replenished.

  On the other hand, as shown in FIGS. 8 and 9, a transport path 180 is provided on the outer surface of the cover 170, and an external supply port 181 communicating with the supply port 174 is provided at one end of the transport path 180. The other end of the conveyance path 180 is provided with an internal supply port 182 communicating with the upstream side of the spiral auger 90 in the conveyance direction.

  A spiral auger 94 smaller in diameter than the spiral augers 90 and 92 is rotatably supported in the transport path 180, and a gear 195 is fixed to the end of the rotating shaft 194 of the spiral auger 94. . In addition, a forward spiral blade 192 formed in a spiral shape is provided around the rotation shaft 194. When the rotational force is transmitted to the gear 195 and the spiral auger 94 rotates via the gear 195, the replenishing port 174 and the outside are provided. The developer replenished into the conveyance path 180 through the supply port 181 is conveyed to the internal supply port 182 by the forward spiral blade 192 and supplied into the housing 150.

  On the other hand, as shown in FIGS. 4, 6 and 10, the toner cartridge 82Y is constituted by a long cylindrical body having a non-circular cross section. A partition cap 106 is provided inside the toner cartridge 82Y, and a toner storage portion 102 for storing new toner to which a small amount of a new carrier is added, and a developer recovery portion for recovering excess developer. 104.

  A supply port 108 for supplying new toner into the housing 150 is provided at the end of the toner storage portion 102, and can communicate with a supply port 174 provided on the outer surface of the housing 150. On the other hand, the developer recovery section 104 is provided with a recovery port 184 for recovering the developer discharged from the housing 150, and the communication port 178 (see FIG. 7) formed in the shutter plate 114 is an arc. The recovery port 184 can communicate with the communication port 178 and the discharge port 176 in a state where it communicates with the discharge port 176 formed in the receiving plate 172.

  Here, as shown in FIG. 8, a nozzle 186 projects from the peripheral edge of the discharge port 176 into the housing 150, and the developer in the housing 150 is guided to the discharge port 176 through the nozzle 186. The

  As shown in FIG. 13A, when the developing unit 18Y is located at the developing position (position B in FIG. 4) where the developing roll 88 faces the photosensitive drum 12, the nozzle 186 faces obliquely downward. The angle is set. For this reason, when the developing device 18Y is located at the developing position, the developer in the housing 150 is not collected by the developer collecting unit 104.

  Then, as shown in FIG. 13B, when the developing unit 18Y moves 90 ° from the developing position, the angle of the nozzle 186 is set to face obliquely upward. The inclination angle of the nozzle 186 is set to be steeper than the inclination angle of the developer in the housing 150. Therefore, as shown in FIG. 13C, when the amount of developer contained in the housing 150 increases, the rotation of the rotary 39 causes the developing device 18Y to move counterclockwise by about 90 ° from the developing position. In addition, the developer at a position higher than the height of the front end surface of the nozzle 186 is discharged through the nozzle 186 to the developer collection unit 104 through the discharge port 176, the communication port 178 and the collection port 184.

  This is the so-called trickle system, and a small amount of new carrier is gradually replenished with new toner inside the developing device in order to prevent a decrease in developer charging performance and extend the interval of developer replacement. In this method, development is performed while discharging an excessive amount of developer (including many deteriorated carriers) from the inside of the developing device.

  Incidentally, as shown in FIGS. 6 and 10, a supply port of the toner storage unit 102 is provided on the outer periphery (including part of the toner storage unit 102) of the developer recovery unit 104 formed in a cylindrical shape of the toner cartridge 82Y. A shutter member 128 that opens and closes the recovery port 108 and the recovery port 184 of the developer recovery unit 104 is rotatably inserted along the circumferential direction.

  As shown in FIGS. 10 and 11, the shutter member 128 is provided with a supply opening 130 and a collection opening 132 at positions corresponding to the supply port 108 and the collection port 184 of the toner cartridge 82Y, respectively. The supply port 108 and the recovery port 184 of the toner cartridge 82Y can be simultaneously opened and closed by rotating the shutter member 128 along the outer periphery of the developer recovery unit 104 of the toner cartridge 82Y. Yes.

  Further, the shutter member 128 is configured to rotate the shutter member 128 to a part in the circumferential direction of the shutter member 128, hold the shutter member 128, and attach the toner cartridge 82Y to the developing device 18Y. A handle 134 protrudes outward in the radial direction.

  In the handle 134, when the toner cartridge 82Y is mounted on the developing device 18Y and the supply port 108 and the recovery port 184 are opened, the top portion 134A coincides with the corner portion 83 of the toner cartridge 82Y (see A in FIG. 4). In the state where the supply port 108 and the recovery port 184 are closed, the top portion 134A and the corner portion 83 are arranged in a shifted state, and the handle 134 is configured to protrude from the outer periphery of the developing device 18.

  As shown in FIG. 11, when the toner cartridge 82Y is removed from the developing device 18Y, the movement of the shutter member 128 is restricted, and the supply port 108 and the recovery port 184 of the toner cartridge 82Y are not accidentally opened. Yes. As shown in FIG. 5, when the toner cartridge 82Y is mounted at a predetermined position of the developing unit 18Y and the supply port 108 and the recovery port 184 of the toner cartridge 82Y are opened, the toner cartridge 82Y is inserted into the developing unit 18Y. Can not be removed from.

  In this embodiment, when the toner cartridge 82Y is mounted at a predetermined position of the developing device 18Y, the rotating shaft member of the developing device 18 is moved from the outside in the radial direction of the developing device 18 shown in FIG. The toner cartridge 82Y can be easily attached to and detached from the developing device 18Y by sliding along the housing 150 of the developing device 18Y in the 41 direction.

  When replacing the toner cartridge 82Y with a new one, as shown in FIG. 2, the developing device 18 is stopped so that the toner cartridge 82Y to be replaced is placed at the replacement position B, and the toner cartridge 82Y is placed on the side surface of the printer 10. The side cover 97 provided is opened, and the toner cartridge 82Y to be replaced is taken out.

  Here, as shown in FIG. 6, when the toner cartridge 82Y is removed from the developing device 18Y, the handle 134 of the shutter member 128 is rotated by hand, and the shutter member 128 is rotated clockwise. As the shutter member 128 rotates, the supply port 108 and the recovery port 184 of the toner cartridge 82Y are closed.

  Then, with the handle 134 of the shutter member 128 stopped moving, the supply port 108 and the recovery port 184 of the toner cartridge 82Y are completely closed. In this state, the toner cartridge 82Y can be detached from the developing device 18Y.

  Next, the main part of the developing device according to the embodiment of the present invention will be described.

  As shown in FIGS. 9 and 12, the developing unit 18Y (note that the developing units 18Y, 18M, 18C, and 18K are all configured in the same manner, and here, the yellow (Y) developing unit 18Y is taken as an example. The spiral auger 90 disposed in the inside is provided with a forward spiral blade 164 formed in a spiral shape around the rotation shaft 162. The spiral is shaped in the direction of the arrow (forward direction) by rotation. With this spiral shape, the developer in the space 154 is conveyed in the direction of the arrow while being stirred.

  On the other hand, as shown in FIG. 4, a nozzle 186 protrudes into the housing 150 from the peripheral edge of the discharge port 176 formed in the cover 170 of the developing device 18 </ b> Y, and the developer accommodated in the housing 150. When the developing device 18Y is moved to the position B in FIG. 4 by the rotation of the developing device 18, the developer at a position higher than the height of the tip end surface of the nozzle 186 passes through the nozzle 186 and the discharge port 176. The developer is discharged to the developer collecting unit 104 through the communication port 178 and the collecting port 184.

  By the way, in the present embodiment, a two-component developer composed of toner and carrier is used, and the toner and carrier are mixed by the rotation of the spiral augers 90 and 92, but in order to reduce the size of the developing device 18Y. Since the developer transport distance is shortened, some measures are required to increase the stirring ability in order to sufficiently mix the toner and the carrier.

  Therefore, in the present embodiment, as shown in FIG. 9, a first staying part 154A and a second staying part 154B in which the developer stays are provided in the space 154 on the toner supply side to increase the developer stirring ability. ing.

  The first staying part 154A provided closer to the internal supply port 182 than the second staying part 154B includes three rectifying plates 161 formed on the rotary shaft 162 of the spiral auger 90 disposed in the space 154, It is comprised by the protrusion part 150A formed in the housing 150. FIG. The rectifying plates 161 are rectangular plate materials, and are arranged in a line along the axial direction of the rotating shaft 162 between one pitch of the stirring blades 164. The rectifying plate 161 applies a transport load to the developer transported by the rotating stirring blade 164, and the transport capacity of the developer is lower in the first staying part 154 </ b> A than in other parts of the space 154. doing.

  Similarly to the first staying part 154A, the three staying plates 161 are also provided to the second staying part 154B provided on the downstream side in the transport direction by two pitches of the stirring blade 164 from the first staying part 154A. Is provided, and the developer transport capability is reduced as compared with other portions of the space 154. Note that the amount of protrusion of the rectifying plate 161 from the rotating shaft 162 is smaller than the amount of protrusion of the stirring blade 164 from the rotating shaft 162.

  Further, the protruding portion 150 </ b> A constituting the first staying portion 154 </ b> A protrudes from the surface of the housing 150 facing the rectifying plate 161 toward the rectifying plate 161. The clearance between the projecting portion 150A and the stirring blade 164 is large enough to prevent interference between the two. Further, both end portions of the projecting portion 150A are formed in a tapered shape so as not to store the developer.

  Here, the developer to be transported is reduced in transport capability by the current plate 161, but is not completely blocked by the current plate 161. That is, the developer tends to flow around the rectifying plate 161 to avoid it. However, in this embodiment, the developer that tries to pass around the current plate 161 is blocked by the protrusion 150A. For this reason, the developer stays in the first staying portion until the current plate 161 is retracted from the first staying portion 154 </ b> A by the rotation of the rotating shaft 162. Therefore, the developer can be sufficiently stirred in the first staying portion 154A, and image defects due to poor stirring of the developer can be prevented.

  The first staying part 154A is provided at a position separated from the internal supply port 182 by one pitch of the stirring blade 164 toward the downstream side in the transport direction. For this reason, the developer crest formed by the flow regulating plate 161 and the protrusion 150A is blocked by the stirring blade 164 for one pitch, so that the developer crest does not block the internal supply port 182.

  The protruding portion 150A is provided only at a position facing the upstream rectifying plate 161, not the downstream rectifying plate 161. This is due to the following reason.

  On the upstream side, by making the protruding portion 150A face the rectifying plate 161, it is possible to amplify the staying effect due to the rectifying plate 161 reducing the developer conveying ability. Since the toner is transported again in an area having a normal transport capability, a developer valley is formed.

  The stirrability can be further improved by providing the current plate 161 again on the downstream side of the valley to lower the conveying capacity and form the staying portion.

  However, if the protruding portion 150A is provided in the downstream staying portion, the transporting capacity of the upstream staying portion and the transporting capability of the downstream staying portion become equal, resulting in formation between the two. Since the developer valleys become shallow, the effect of improving the stirring performance is impaired.

  As described above, in this embodiment, by providing the protruding portion 150A only at a position facing the upstream rectifying plate 161 instead of the downstream rectifying plate 161, the developer agitation performance is further improved. We realize effect to improve.

  In the present embodiment, the present invention has been described by taking the developing device provided in the rotary developing device 18 as an example. However, the present invention is not limited to this, and the developing device provided in another type of developing device may also be used. The present invention is applicable.

1 is a configuration diagram of an image forming apparatus according to an embodiment of the present invention. 1 is a configuration diagram of an image forming apparatus according to an embodiment of the present invention, showing a state where an image forming unit is removed. FIG. 1 is a perspective view showing a rotary developing device constituting an image forming apparatus according to an embodiment of the present invention. 1 is a cross-sectional view showing a rotary developing device constituting an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a perspective view showing a developing device and a toner cartridge of the developing device according to the embodiment of the present invention. FIG. 2 is an exploded perspective view showing a developing device and a toner cartridge of the developing device according to the embodiment of the present invention. It is a perspective view which shows the developing device of the developing device which concerns on embodiment of this invention. FIG. 2 is an exploded perspective view showing a housing and a cover of a developing device of the developing device according to the embodiment of the present invention. FIG. 4 is a plan view of the housing side of the developing device of the developing device according to the embodiment of the present invention. FIG. 4 is a cross-sectional view of a toner cartridge mounted on a developing device of a developing device according to an embodiment of the present invention. FIG. 6 is a perspective view of a toner cartridge mounted on a developing device of the developing device according to the embodiment of the present invention. It is a perspective view of the spiral auger in the developing device of the developing device according to the embodiment of the present invention. FIGS. 3A to 3C are cross-sectional views illustrating a developing device and a toner cartridge of a developing device according to an embodiment of the present invention.

Explanation of symbols

12 Photosensitive drum (image carrier)
18C Developer 18M Developer 18Y Developer 18K Developer 88 Developer roll 90 Spiral auger (stirring member)
92 Spiral auger (stirring member)
150 Housing 150A Protruding part (protruding member)
161 Current plate (conveying load member)
162 Rotating shaft 164 Agitation blade 182 Internal supply port (toner supply port)

Claims (3)

A plurality of agitating members having spiral agitating blades formed on the rotating shaft convey the developer in the housing while agitating the developer along the developing roll, and the developing roll is agitated by the agitating member. A developing device for developing the image carrier with
A transport load member protruding from the rotating shaft and receiving a transport load from the developer;
A projecting member that projects from the housing toward the transport load member and retains the developer around the transport load member;
A developing device comprising:   The developing device according to claim 1, wherein the conveyance load member and the protruding member are provided at a distance of one pitch or more from a toner supply port to the housing.   3. The developing device according to claim 1, wherein a plurality of the transport load members are provided, and the protruding member is provided to face the transport load member on a toner supply port side to the housing.

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