JP2010026487A - Developing device and image forming apparatus equipped therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device, capable of effectively preventing toner which is not sufficiently charged, from being supplied to a developer carrier member, even if the supplied toner is conveyed on developer in a lumped state, and an image forming apparatus equipped therewith. <P>SOLUTION: In the developing device 2, a first conveying screw 112a has a return blade 52 configured to convey in reverse the developer conveyed in a circulating direction. The return blade 52 is disposed on a downstream side in the circulating direction in a toner supply port 117 and forms developer accumulation J, and space W above the developer is blocked through toner accumulation. According to this blocking, the supplied toner is prevented from moving, while it is conveyed on the upper surface (developer surface) of the developer, existing from before inside a first conveying path P, into a lumped state. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a developing device that is provided in an electrophotographic image forming apparatus and handles a two-component developer containing toner and a carrier, and an image forming apparatus including the developing device.

  2. Description of the Related Art Conventionally, electrophotographic image forming apparatuses such as copying machines, printers, and facsimiles are known. An electrophotographic image forming apparatus forms an electrostatic latent image on the surface of a photoreceptor (toner image carrier), and supplies toner to the electrostatic latent image by a developing device to form the electrostatic latent image. Development is performed, and a toner image formed by development is transferred and fixed on a sheet such as paper.

  2. Description of the Related Art In recent years, two-component developers (hereinafter sometimes simply referred to as “developers”) that are excellent in toner charging stability are often used in image forming apparatuses that support colorization and high image quality. The two-component developer is composed of toner and carrier, and when they are agitated in the developing device, the toner and the carrier are rubbed, and a properly charged toner is obtained by this friction. The charged toner is supplied to the surface of a developer carrying member such as a developing roller. The toner on the developer carrying member moves to an electrostatic latent image formed on the image carrier (photosensitive member) by electrostatic attraction. As a result, a toner image is formed on the photoreceptor.

  Recently, there has been a demand for speeding up and downsizing of an image forming apparatus, and it has become necessary to quickly and sufficiently charge the developer and to transport the developer quickly.

  In order to meet the above requirements, a circulation type developing device is frequently used. The circulation type developing device includes a developer transport path through which the developer is circulated and transported, and a developer transport member that transports the developer while stirring the developer in the developer transport path. The developer is quickly and sufficiently charged while being transported while being stirred in the developer transport path by the developer transport member.

  In such a circulation type developing device, a toner hopper is provided at the upper portion of the developing device, and when the toner concentration of the developer inside the developing device falls below a predetermined value, the toner hopper is transferred to the developer conveying path. The toner is replenished. The replenished toner (hereinafter also referred to as replenishment toner) is mixed and charged with a certain developer while being conveyed through the developer conveyance path.

  However, in such a circulation type developing device, the replenished toner is not sufficiently mixed with the carrier (a conventional developer), that is, in a state of a low charge amount that is not sufficiently charged. It may be supplied to the developer carrying member.

  If toner that is not sufficiently charged is supplied to the developer carrying member, there is a problem that the toner is scattered from the developer carrying member, and the inside of the image forming apparatus and the formed image are stained. Further, if toner that is not sufficiently charged is supplied to the developer carrying member, the electrostatic force for holding the toner on the surface of the carrier is reduced, and the toner adheres to the non-image area and is likely to be fogged. Problems also arise.

In view of such a problem, Patent Document 1 describes a configuration in which a mesh-like screen member through which a developer passes a plurality of times is arranged in the developer conveyance path. In one example, the developer conveying member is composed of a screw having a torsion-like wing body around the rotation axis, and a screen member is disposed between the wing body.
Japanese Patent Laid-Open No. 10-63081 (Publication date: March 6, 1998)

  However, even in the developing device in which the scoon member is disposed, the amount of toner (supplemented toner amount) replenished from the toner hopper to the developer transport path is large and solidified, and the upper surface (development) There is a problem that the developer surface) is transported and cannot be sufficiently mixed with a certain developer, and is supplied to the developer carrying member in a state where it is not sufficiently charged.

  As one countermeasure for solving such a problem, a configuration in which the upper space formed on the upper surface of the developer is completely eliminated in the developer transport path is conceivable. However, in such a configuration, an excessive stress is applied to the developer, and the wear of the developer is promoted, so that the life of the developer is shortened or the developer cannot be conveyed.

  This is considered due to a change in the volume (volume) of the developer. In other words, the volume of the developer constantly changes due to changes in the toner concentration and the toner charge amount in the developer, but in the above configuration, there is no space for absorbing such changes, and the internal pressure of the developer is low. As a result, it is considered that the developer is excessively stressed.

  In addition, when the bulk of the developer increases in the vicinity of the toner supply port, there is a problem that the supply toner forms a bridge at the toner supply port and closes the toner supply port.

  According to the present invention, in a developing device provided in an electrophotographic image forming apparatus, even if replenished toner is hardened and transported on the developer without giving excessive stress to the developer, it is sufficient. It is an object of the present invention to provide a developing device capable of effectively suppressing uncharged toner from being supplied to a developer carrying member, and an image forming apparatus including the developing device.

  In order to solve the above-described problems, the developing device of the present invention includes a developing tank that stores a developer containing toner and a carrier, and a first tank and a first tank that are provided in the developing tank and transport the developer. Two conveying paths, a first conveying member provided in the first conveying path for conveying the developer in a predetermined direction while stirring the developer in the first conveying path, and a first conveying member provided in the second conveying path. A second conveying member that conveys the developer in a direction opposite to the predetermined direction while stirring the developer in the two conveying paths; and first and second ends that communicate with each other at both ends in the longitudinal direction of the first and second conveying paths. A second communication path; a developer carrying member that carries the developer in the second transport path and supplies toner contained in the developer to the photoconductor; and the developer transported in the first transport path A developer tank cover that covers the top surface of the first transport path leaving a space above the first transport path. A toner replenishing port for replenishing toner, and the developer is conveyed so as to circulate in this order in the first conveying path, the first communicating path, the second conveying path, and the second communicating path. In the developing device, an upper space blocking means for blocking the upper space of the developer conveyed along the first conveyance path is provided on the downstream side in the circulation direction of the toner supply port in the first conveyance path. It is characterized by being.

  According to the above configuration, the space above the developer conveyed in the first conveyance path is blocked by the upper space blocking means on the downstream side in the circulation direction of the toner supply port. The toner replenished from the mouth is transported on the upper surface (developer surface) of the developer in the first transport path in a solidified state, and is prevented from moving.

  As a result, even if the replenished toner is hardened and transported on the developer, the replenished toner is not sufficiently mixed with the developer, and the developer is not sufficiently charged. Supplying to the carrying member can be effectively suppressed, and occurrence of fogging and toner scattering can be suppressed when mounted on the image forming apparatus.

  In the developing device according to the aspect of the invention, the first conveying member may further include a return blade that conveys the developer conveyed in the circulation direction in the reverse direction to form a developer reservoir, and the circulation direction in the toner supply port. Provided on the downstream side, the upper space blocking means comprises the return blade provided in the first conveying member, the developer reservoir formed by the return blade is brought into contact with the developer tank cover, It can also be set as the structure which blocks upper space.

  According to the above configuration, the developer pool with the upper surface of the developer raised is formed in the vicinity of the return blade by the action of the return blade provided on the first conveying member. The developer pool is formed downstream of the toner supply port in the circulation direction.

  Therefore, even when the replenishment toner is solidified and conveyed on the developer, the replenishment toner lump is prevented from passing as it is when passing through the developer reservoir, and is forced. It is relaxed. Also, the reverse rotation of the return blade increases the developer mixing effect, and the replenishment toner is sufficiently mixed with the existing developer here and rubbed against the contained carrier.

  Thereby, even when the replenished toner is hardened and conveyed on the developer, it is possible to effectively suppress the supply of the toner that is not sufficiently charged to the developer carrying member. it can.

  In order to solve the above-mentioned problems, the developing device according to the present invention is further characterized in that the return blade is a spiral screw auger that conveys the developer in a direction opposite to the circulation direction.

  According to the above configuration, since the developer pool can be formed in the vicinity of the return blade without significantly increasing the stress (shearing force) on the developer, it is possible to suppress the wear deterioration of the developer.

  In order to solve the above-described problems, the developing device according to the present invention further includes a spiral conveying blade in which the first conveying member is formed continuously with the return blade and conveys the developer in the circulation direction. It is characterized by having.

  According to the above configuration, the developer can be transported without increasing the stress (shearing force) on the developer, so that toner that is not sufficiently charged is prevented from being supplied to the developer carrying member. The developer conveyance speed can be increased.

  In order to solve the above problems, the developing device according to the present invention is further characterized in that the diameter of the return blade is smaller than the diameter of the conveying blade of the first conveying member.

  According to the above configuration, in the configuration in which the diameters of the return blade and the conveying blade are approximately the same, the force for conveying the developer in the circulation direction is equal to the force for conveying the developer in the reverse direction. High stress is applied to the drug.

  On the other hand, as described above, by reducing the return blade, even if a force for conveying the developer in the circulation direction and a force for conveying the developer in the opposite direction are applied to the developer, such stress is applied. Can be made lower than a configuration with a similar diameter.

  As a result, the replenishment toner can be mixed with a certain developer without applying a significantly high stress to the developer.

  In order to solve the above-described problems, the developing device according to the present invention is further characterized in that a developer regulating member that regulates the upper surface of the developer is provided above the return blade.

  According to the above configuration, the lump of the replenishment toner conveyed on the developer is more reliably solved by colliding with the developer regulating member. In addition, the replenishment toner can be more effectively mixed with the existing developer by the developer regulating member.

  In order to solve the above-described problems, the developing device according to the present invention can be further characterized in that the carrier is a magnetic carrier and the developer regulating member is a magnet.

  According to the above configuration, a carrier in a certain developer can be attracted to a developer regulating member made of a magnet, so that a developer reservoir having a high carrier concentration can be formed.

  Accordingly, the replenished toner that has been transported over the developer in a solid state is loosened and mixed with the developer in the developer reservoir having a high carrier concentration, so that it is more effectively charged.

  As a result, it is possible to more effectively suppress toner that is not sufficiently charged from being supplied to the developer carrying member.

  In the developing device according to the present invention, in order to solve the above-described problem, the first transport is further provided with the upper space blocking means provided downstream in the circulation direction of the toner supply port in the first transport path. The movable weir comprises a movable weir that contacts the upper surface portion of the developer conveyed in the path and blocks the developer, and the movable weir blocks the upper space during the toner replenishment mode, and other than during the toner replenishment mode. Is characterized in that the upper space is opened.

  According to the above configuration, since the space above the developer is sealed by the movable weir, the lump of the replenished toner that has been transported on the upper surface of the developer is sandwiched between the developer and the developer tank cover, and is released. It is surely solved by being crushed. Moreover, since the space above the developer is opened except during the toner replenishment mode, the stress on the developer can be more effectively suppressed.

  In order to solve the above problems, the developing device according to the present invention further includes a developer regulating member in which the movable weir is provided perpendicular to the circulation direction and in contact with the upper surface portion of the developer. A rotation shaft that rotatably supports the developer regulating member on a side opposite to a side in contact with the upper surface portion of the developer; and a gear that transmits a rotational driving force to the rotation shaft. And the upper space is sealed and opened.

  According to the above configuration, since the space above the developer can be blocked and opened in a short time by rotating the developer regulating member, the blocking and opening can be finely controlled according to the timing of toner replenishment. .

  In the developing device according to the present invention, in order to solve the above-described problem, the developer restricting member further rotates about the rotation shaft to the downstream side in the circulation direction to open the upper space. It is a feature.

  According to the above configuration, when the movable weir is opened, the developer regulating member constituting the movable weir rotates to the downstream side in the circulation direction (downstream side in the developer transport direction), so the developer regulating member, the developer tank cover, The movable weir can be opened without sandwiching the developer therebetween.

  In the developing device according to the present invention, in order to solve the above-described problem, the first conveying member further includes a return blade for conveying the developer conveyed in the circulation direction in the reverse direction to form a developer reservoir. A developer regulating member provided on the downstream side in the circulation direction of the toner replenishing port, and provided on the upper portion of the return blade perpendicularly to the circulation direction, and the upper space blocking means is a developer regulating member. And the return vane provided in the first conveying member, and the developer reservoir formed by the return vane is dammed up by the developer regulating member, thereby contacting the developer reservoir with the developer tank cover And the above-mentioned space is sealed.

  According to the above configuration, the developer regulating member and the return blade provided in the first transport member function as an upper space blocking means, and the developer pool formed by the return blade is blocked by the developer regulating member. In this way, the developer reservoir is brought into contact with the developer tank cover to seal the space above the developer.

  In order to solve the above problems, an image forming apparatus according to the present invention includes the developing device according to the present invention.

  As described above, the developing device according to the present invention includes such a developing device because it can effectively prevent the toner that is not sufficiently charged from being supplied to the developer carrying member. The image forming apparatus of the present invention can be configured such that the problem of toner scattering and image fogging hardly occurs.

  As described above, the developing device according to the present invention seals the space above the developer transported in the first transport path on the downstream side in the circulation direction of the toner supply port in the first transport path. Is provided.

  As a result, even when the replenished toner is hardened and conveyed on the developer, it is possible to effectively prevent the toner that is not sufficiently charged from being supplied to the developer carrying member. The problem of scattering and image fogging can be reduced.

[Embodiment 1]
An embodiment of the present invention will be described below with reference to FIGS.

  First, before describing the developing device, an image forming apparatus provided with the developing device will be described.

(Configuration of image forming apparatus)
FIG. 2 is a schematic diagram illustrating an internal configuration of the image forming apparatus 100 including the developing device according to the present embodiment. In the drawings attached to the present specification, the vertical direction (direction in which gravity acts) is defined as the G direction, and the direction opposite to the G direction is defined as the H direction.

  The image forming apparatus 100 is an electrophotographic printer, and forms a multicolor or single color image on a predetermined sheet (recording paper, recording medium) according to image data transmitted from the outside. Note that a scanner or the like may be provided above the image forming apparatus 100.

  The image forming apparatus 100 handles image data for each color component of black (K), cyan (C), magenta (M), and yellow (Y), and forms a black image, a cyan image, a magenta image, and a yellow image. A color image is formed by superimposing the images of the respective color components.

  Therefore, as shown in FIG. 2, in the image forming apparatus 100, the developing device 2 (2a, 2b, 2c, 2d) and the photosensitive drum 3 (3a, 3b, 3c) are formed so that an image of each color component is formed. , 3d), four chargers 5 (5a, 5b, 5c, 5d) and four cleaner units 4 (4a, 4b, 4c, 3d). In other words, four image forming stations (image forming units) each including the developing device 2, the photosensitive drum 3, the charger 5, and the cleaner unit 4 are provided.

  The symbols a to d indicate that a is a member for forming a black image, b is a member for forming a cyan image, c is a member for forming a magenta image, and d is a member for forming a yellow image. It is a thing. In addition, the image forming apparatus 100 includes an exposure unit 1, a fixing unit 12, a sheet conveyance path S, a paper feed tray 10, and a paper discharge tray 15.

  The charger 5 uniformly charges the surface of the photosensitive drum 3 to a predetermined potential. As the charger 5, in addition to the contact roller type charger shown in FIG. 2, a contact brush type charger or a non-contact charger type charger may be used.

  The exposure unit 1 is a laser scanning unit (LSU) provided with a laser irradiation unit and a reflection mirror as shown in FIG. However, in addition to the laser scanning unit, the exposure unit 1 may be an EL or LED writing head in which light emitting elements are arranged in an array. The exposure unit 1 exposes the charged photosensitive drum 3 according to the input image data, thereby forming an electrostatic latent image corresponding to the image data on the surface of the photosensitive drum 3.

  The developing device 2 visualizes (develops) the electrostatic latent image formed on the photosensitive drum 3 with one of K, C, M, and Y toners. The developing device 2 (2a, 2b, 2c, 2d) includes a developing tank 111 (111a, 111b, 111c, 111d), and a toner hopper 101 (101a, 101b, 101c, 101d) on the H direction side of the developing tank 111. And a toner transfer mechanism 102 (102a, 102b, 102c, 102d). The toner hopper 101 stores unused toner (powder toner). Toner is supplied from the toner hopper 101 to the developing tank 111 via the toner transfer mechanism 102.

  The cleaner unit 4 removes and collects the toner remaining on the surface of the photosensitive drum 3 after the development and image transfer processes.

  An intermediate transfer belt unit 8 is disposed above the photosensitive drum 3. The intermediate transfer belt unit 8 includes an intermediate transfer roller 6 (6a, 6b, 6c, 6d), an intermediate transfer belt 7, an intermediate transfer belt driving roller 71, an intermediate transfer belt driven roller 72, an intermediate transfer belt tension mechanism 73, and an intermediate transfer. A belt cleaning unit 9 is provided.

  The intermediate transfer belt 6, the intermediate transfer belt drive roller 71, the intermediate transfer belt driven roller 72, and the intermediate transfer belt tension mechanism 73 stretch the intermediate transfer belt 7 and rotationally drive the intermediate transfer belt 7 in the direction of arrow B in FIG. It is something to be made.

  The intermediate transfer roller 6 is rotatably supported by an intermediate transfer roller mounting portion in the intermediate transfer belt tension mechanism 73 of the intermediate transfer belt unit 8. A transfer bias for transferring the toner image on the photosensitive drum 3 onto the intermediate transfer belt 7 is applied to the intermediate transfer roller 6.

  The intermediate transfer belt 7 is provided so as to be in contact with each photosensitive drum 3. A color toner image (multicolor toner image) is formed on the intermediate transfer belt 7 by sequentially superimposing and transferring the toner images of the respective color components formed on the photosensitive drum 3. The intermediate transfer belt 7 is formed in an endless shape using a film having a thickness of, for example, about 100 μm to 150 μm.

  Transfer of the toner image from the photosensitive drum 3 to the intermediate transfer belt 7 is performed by the intermediate transfer roller 6 in contact with the back side of the intermediate transfer belt 7. A high voltage transfer bias (a high voltage having a polarity (+) opposite to the toner charging polarity (−)) is applied to the intermediate transfer roller 6 in order to transfer the toner image.

  The intermediate transfer roller 6 is formed based on a metal (for example, stainless steel) shaft having a diameter of, for example, 8 to 10 mm, and the surface is covered with a conductive elastic material (for example, EPDM, urethane foam, or the like). With this conductive elastic material, the intermediate transfer roller 6 can uniformly apply a high voltage to the intermediate transfer belt 7. In this embodiment, a roller-shaped transfer electrode (intermediate transfer roller 6) is used as the transfer electrode, but a brush or the like can also be used.

  As described above, the electrostatic latent images on the respective photosensitive drums 3 are visualized with toners corresponding to the respective color components to become toner images, and these toner images are superimposed and laminated on the intermediate transfer belt 7. As described above, the stacked toner images are moved to a contact position (transfer portion) between the conveyed paper and the intermediate transfer belt 7 by the rotation of the intermediate transfer belt 7, and the transfer roller disposed at this position is moved. 11 is transferred onto the paper. In this case, the intermediate transfer belt 7 and the transfer roller 11 are pressed against each other at a predetermined nip, and a voltage for transferring the toner image onto the sheet is applied to the transfer roller 11. This voltage is a high voltage having a polarity (+) opposite to the charging polarity (−) of the toner.

  In order to obtain the nip constantly, either the transfer roller 11 or the intermediate transfer belt drive roller 71 is made of a hard material such as metal, and the other is a soft material such as an elastic roller (elastic rubber roller or foamable resin roller). Etc.).

  The toner adhering to the intermediate transfer belt 7 due to the contact between the intermediate transfer belt 7 and the photosensitive drum 3 and the toner image remaining on the intermediate transfer belt 7 without being transferred when the toner image is transferred from the intermediate transfer belt 7 to the sheet. The toner is removed and collected by the intermediate transfer belt cleaning unit 9 because it causes toner color mixing in the next step. The intermediate transfer belt cleaning unit 9 is provided with a cleaning blade (cleaning member) that contacts the intermediate transfer belt 7. The portion of the intermediate transfer belt 7 that is in contact with the cleaning blade is supported by the intermediate transfer belt driven roller 72 from the back side.

  The paper feed tray 10 is for storing sheets (for example, recording paper) used for image formation, and is provided below the image forming unit and the exposure unit 1. On the other hand, a paper discharge tray 15 provided in the upper part of the image forming apparatus 100 is for placing printed sheets face down.

  Further, the image forming apparatus 100 is provided with a sheet conveyance path S for guiding the sheet of the paper feed tray 10 and the sheet of the manual feed tray 20 to the paper discharge tray 15 via the transfer unit and the fixing unit 12. . The transfer unit is located between the intermediate transfer belt driving roller 71 and the transfer roller 11.

  Further, in the sheet conveyance path S, a pickup roller 16 (16a and 16b), a registration roller 14, a transfer unit, a fixing unit 12, a conveyance roller 25 (25a to 25h), and the like are arranged.

  The conveyance rollers 25 are small rollers for promoting and assisting conveyance of the sheet, and a plurality of conveyance rollers 25 are provided along the sheet conveyance path S. The pickup roller 16 a is a pull-in roller that is provided at the end of the paper feed tray 10 and supplies sheets from the paper feed tray 10 to the sheet conveyance path S one by one. The pickup roller 16b is a drawing roller that is provided near the manual feed tray 20 and supplies sheets from the manual feed tray 20 to the sheet conveyance path S one by one. The registration roller 14 temporarily holds the sheet conveyed in the sheet conveyance path S, and conveys the sheet to the transfer unit at a timing when the leading edge of the toner image on the intermediate transfer belt 7 and the leading edge of the sheet are aligned.

  The fixing unit 12 includes a heat roller 81, a pressure roller 82, and the like. The heat roller 81 and the pressure roller 82 rotate with the sheet interposed therebetween. The heat roller 81 is controlled by a control unit (not shown) so as to have a predetermined fixing temperature. This control unit controls the temperature of the heat roller 81 based on a detection signal from a temperature detector (not shown). The heat roller 81 thermally press-bonds the sheet together with the pressure roller 82 to melt, mix, and press the color toner images transferred to the sheet, and heat-fix the sheet. The sheet on which the multicolor toner image (each color toner image) is fixed is conveyed to the reverse sheet discharge path of the sheet conveyance path S by the plurality of conveyance rollers 25 and is reversed (the multicolor toner image is on the lower side). Are discharged onto the paper discharge tray 15.

  Next, the sheet conveying operation by the sheet conveying path S will be described. As described above, the image forming apparatus 100 includes the paper feed tray 10 that stores sheets in advance and the manual feed tray 20 that is used when printing a small number of sheets. A pickup roller 16 is disposed in each of the two, and these pickup rollers 16 supply sheets one by one to the sheet conveyance path S.

  In the case of single-sided printing, the sheet conveyed from the sheet feeding tray 10 is conveyed to the registration roller 14 by the conveyance roller 25a in the sheet conveyance path S, and is stacked on the leading edge of the sheet and the intermediate transfer belt 7 by the registration roller 14. The toner image is conveyed to the transfer unit at a timing when the leading edge of the toner image is aligned. In the transfer portion, a toner image is transferred onto the sheet, and this toner image is fixed on the sheet by the fixing unit 12. Thereafter, the sheet is discharged onto the discharge tray 15 from the discharge roller 25c via the conveyance roller 25b. Further, the sheet conveyed from the manual feed tray 20 is conveyed to the registration roller 14 by a plurality of conveying rollers 25 (25f, 25e, 25d). Thereafter, the sheet is discharged to the discharge tray 15 through the same process as that of the sheet supplied from the sheet supply tray 10.

  In the case of double-sided printing, as described above, single-sided printing is completed, and the sheet that has passed through the fixing unit 12 is chucked at the trailing edge by the paper discharge roller 25c. Next, the sheet is guided to the transport rollers 25g and 25h by the reverse rotation of the paper discharge roller 25c, and after the back side printing is performed through the registration roller 14, the sheet is discharged to the paper discharge tray 15.

(Configuration of developing device)
Next, the developing device 2 provided in the image forming apparatus 100 will be described in detail. 3 is a cross-sectional view of the developing device 2, FIG. 4 is an arrow diagram along line AA ′ of the developing device 2 shown in FIG. 3, and FIG. 5 is a arrow line BB ′ of the developing device 2 shown in FIG. It is an instruction.

  As shown in FIG. 3, the developing device 2 has a developer carrying member (developing roller) 114 disposed in the developing tank 111 so as to face the photosensitive drum 3 (see FIG. 2). This is a device for developing (developing) an electrostatic latent image formed on the surface of the photosensitive drum 3 by supplying toner to the surface of the photosensitive drum 3 by the agent carrying member 114.

  As shown in FIG. 3, the developing device 2 includes a developing tank 111 and a developer carrying member 114, a developing tank cover (ceiling surface) 115, a doctor blade 116, a first conveying screw (first conveying member) 112 a, 2 conveyance screw (2nd conveyance member) 112b and the partition plate (partition wall) 113 are provided.

  The developing tank 111 is a tank for storing a developer containing toner and a carrier, and a developer carrying member 114, a first conveying screw 112a, and a second conveying screw 112b are disposed in the developing tank 111. Note that the carrier of this embodiment is a magnetic carrier having magnetism.

  The developer carrying member 114 is a rotating magnet roller, which draws and carries the developer in the developing tank 111 on the surface, and supplies toner contained in the developer carried on the surface to the photosensitive drum 3. is there. A doctor blade (layer thickness regulating blade) 116 is disposed at a position close to the surface of the developer carrying member 114.

  Further, as shown in FIG. 3, a removable developing tank cover 115 is provided on the upper side (H direction side) of the developing tank 111. As shown in FIGS. 4 and 5, the developer tank cover 115 is provided with a toner supply port 117 for supplying unused toner to the developer tank 111. The toner stored in the toner hopper 101 shown in FIG. 2 is supplied to the developing tank 111 through the toner transfer mechanism 102 and the toner supply port 117.

  As shown in FIG. 4, the first transport screw 112 a and the second transport screw 112 b are screw-shaped rollers (stirring rollers) for stirring and transporting the developer in the developing tank 111. The first conveying screw 112 a and the second conveying screw 112 b are formed with a helical conveying blade 51 around the rotating shaft 50 for agitating and conveying the developer.

  The first conveying screw 112a and the second conveying screw 112b are arranged in parallel so that their circumferential surfaces face each other via the partition plate 113, and their rotation shafts 50 are parallel to each other. The first conveying screw 112a and the second conveying screw 112b are rotationally driven by a driving means (not shown) such as a motor so as to convey the developer in opposite directions. In the present embodiment, the first transport screw 112a transports the developer in the X direction shown in FIG. 4, and the second transport screw 112b transports the developer in the Y direction opposite to the X direction.

  The partition plate 113 extends between the first conveying screw 112a and the second conveying screw 112b in parallel with the respective rotation shafts 50 of the first and second conveying screws 112a and 112b. The partition plate 113 divides the inside of the developing tank 111 into a first conveyance path P in which the first conveyance screw 112a is arranged and a second conveyance path Q in which the second conveyance screw 112b is arranged. .

  Further, the partition plate 113 is disposed away from the inner wall surface of the developing tank 111 at both axial ends of the first transport screw 112a and the second transport screw 112b. As a result, in the developing tank 111, communication paths that connect the first transport path P and the second transport path Q are formed near both ends of the first transport screw 112a and the second transport screw 112b in the respective rotational axis directions. Has been.

  In FIG. 4, the communication path formed on the downstream side in the X direction is a first communication path e, and the communication path formed on the downstream side in the Y direction is a second communication path f.

  The developer is circulated and conveyed in the developing tank 111 thus partitioned. Specifically, in the first transport path P, the developer is transported in the X direction while being stirred by the first transport screw 112a, and reaches the first communication path e. The developer that has reached the first communication path e passes through the first communication path e and is conveyed to the second conveyance path Q. The developer is stirred in the second conveyance path Q by the second conveyance screw 112b in the Y direction. To reach the second communication path f. Then, the developer that has reached the second communication path f passes through the second communication path f and is conveyed again to the first conveyance path P.

  In this way, the developer is circulated and conveyed in this order through the first conveyance path P, the first communication path e, the second conveyance path Q, and the second communication path f in the developing tank 111.

  The developer carrying member 114 is located above the second conveying screw 112b disposed in the second conveying path Q, and a part of the developer conveyed in the second conveying path Q is a developer. The carrier member 114 is carried on the surface by the rotation of the carrier member 114 and pumped up. Only the toner in the pumped up developer moves to the photosensitive drum 3, and the carrier in the pumped up developer is returned to the developing tank 111. Accordingly, only the toner is sequentially consumed in the developer in the developing tank 111.

  In order to compensate for such toner consumption, new unused toner is supplied from the toner supply port 117 as described above. In the present embodiment, as shown in FIG. 4, the toner supply port 117 is an area in the first transport path P and is formed at a position on the downstream side in the X direction in the vicinity of the second communication path f. That is, the toner is replenished to the upstream position in the developer transport direction in the first transport path P.

  The replenished toner is agitated by the first conveying screw 112a while being conveyed through the first conveying path P, and is mixed and charged with the developer present in the past. Such agitation and charging due thereto is sufficiently performed while the replenished toner is transported through the first transport path P, and reaches the second transport path Q where the developer carrying member 114 is pumped up. In this case, it is preferable to have a sufficient charge amount.

  Such agitation of the replenished toner and charging due thereto causes a large amount of toner to be replenished, and in the conventional developing device, the replenished toner becomes hard and becomes on the upper surface of the existing developer. Even in the case of being carried on the board, it is necessary to effectively disperse this lump and to mix and agitate with a certain developer.

  In order to make this possible, in the developing device 2 of the present embodiment, as shown in FIGS. 4 and 5, a return blade 52 that transports the developer transported in the X direction is provided. It has been. The return blade 52 is disposed downstream of the toner supply port 117 in the developer transport direction (X direction) and is disposed between the transport blades 51.

  The return blade 52 is configured by a spiral screw auger that conveys the developer in a direction opposite to the circulation direction (reverse direction). As shown in FIG. 6, the spiral conveying blade 51 and the return blade 52 that convey the developer in the circulation direction are continuous, that is, the end portion 51 a of the conveying blade 51 and the end portion 52 a of the return blade 52. Are provided in contact with each other.

  Further, the diameter of the return blade 52 is designed to be smaller than the diameter of the conveyance blade 51 of the first conveyance screw 112a.

(Mixing of supply toner and developer)
FIG. 1 shows how the replenished toner is mixed with a certain developer in the developing device 2 of the present embodiment.

  The replenishing toner T1 replenished from the toner replenishing port 117 of the developing tank 111 falls on the developer (the area indicated by the dots in FIG. 1) that circulates and moves in the first transport path P. The specific gravity is extremely lower than the specific gravity of the developer containing toner and carrier. For example, the specific gravity of the toner is about 0.35 g / cc, whereas the specific gravity of the developer is about 2 g / cc. Therefore, when the amount of replenishment toner replenished on the developer is large, the replenishment toner T1 is conveyed while sliding on the upper surface of the developer without being mixed with the developer.

  In the present embodiment, the first conveying screw 112a is provided with a return blade 52 that conveys the developer conveyed in the circulation direction in the reverse direction, downstream of the toner supply port 117 in the developer conveying direction. .

  Therefore, as shown in FIG. 1, a developer pool J is formed in the vicinity of the return blade 52 by the force of sending the developer on the return blade 52 in the reverse direction. By forming the developer reservoir J, the upper surface (liquid surface) of the developer swells, and the toner mass T1 conveyed while sliding on the upper surface of the developer is prevented from passing as it is, and replenished. The toner lump T2 is forcibly loosened.

  Further, the reverse rotation of the return blade 52 enhances the mixing effect of the developer, and the replenished toner is sufficiently mixed with the existing developer here, and is rubbed with the contained carrier. Charge amount can be obtained.

  Accordingly, even when the replenished toner is hardened and conveyed on the developer, it is possible to effectively suppress the supply of the toner that is not sufficiently charged to the developer carrying member 114. Can do.

  More preferably, as shown in FIG. 1, the developer upper surface in the vicinity of the return blade 52 causes the developer tank cover 115 of the first conveyance path P to be exposed by the reverse conveyance of the developer by the return blade 52. It should be designed so that it touches.

  The upper surface of the developer reservoir J formed in the vicinity of the return blade 52 provided on the first conveying screw 112a comes into contact with the ceiling surface of the developer tank cover 115, whereby the replenishment toner is more reliably loosened more effectively.

  In other words, by designing the developer so that the upper surface of the developer in the vicinity of the return blade 52 is in contact with the developer tank cover 115 of the first transport path P by conveying the developer in the reverse direction by the return blade 52. In the present invention, the space blocking means for blocking the space W (see FIG. 1) above the developer transported in the first transport path P is configured on the downstream side in the circulation direction of the toner supply port 117 in the first transport path P. Is done.

  In other words, the first conveying screw 112a includes the return blade 52 that conveys the developer conveyed in the circulation direction in the reverse direction to form the developer reservoir J on the downstream side in the circulation direction at the toner replenishing port 117. The return blade 52 provided in the conveying screw 112a functions as an upper space sealing means, and the developer reservoir J formed by the return blade 52 is brought into contact with the developer tank cover 115 to seal the upper space W.

  According to the above configuration, the return blade 52 blocks the upper space W of the developer transported along the first transport path P on the downstream side in the circulation direction of the toner replenishing port 117. In a state where the toner replenished from the toner replenishing port 117 is hardened, it is prevented from being transported and moving on the upper surface (developer surface) of the developer in the first transport path P.

  As a result, even if the replenished toner is hardened and transported on the developer, the replenished toner is not sufficiently mixed with the developer, and the developer is not sufficiently charged. Supply to the support member 114 can be effectively suppressed, and generation of fogging and toner scattering can be suppressed when mounted on the image forming apparatus 100.

  In the present embodiment, as the return blade 52, as shown in FIGS. 1 and 4 to 6, a spiral screw auger that conveys the developer in the direction opposite to the circulation direction is used. Accordingly, the developer pool can be formed near the root of the return blade 52 without significantly increasing the stress (shearing force) on the developer. Therefore, the return blade is constituted by, for example, a stirring member including a plurality of stirring blades. Compared to the case, the wear deterioration of the developer can be suppressed.

  Furthermore, in the present embodiment, the first conveying screw 112a is formed to be continuous with the return blade 52 and includes a helical conveying blade 51 that conveys the developer in the circulation direction. The developer can be transported without increasing the shearing force, and the developer transport speed can be increased while preventing toner that is not sufficiently charged from being supplied to the developer carrying member.

  In addition, the diameter of the return blade 52 is configured to be smaller than the diameter of the transport blade 51 of the first transport screw 112a. In a configuration in which the diameters of the return blade and the conveying blade are approximately the same, the force for conveying the developer in the circulation direction and the force for conveying the developer in the reverse direction are equal, and thus a high stress is applied to the developer. It takes.

  On the other hand, if the return blade 52 is made small as in the above configuration, even if a force for conveying the developer in the circulation direction and a force for conveying the developer in the opposite direction are applied to the developer, this is applied. The stress can be lower than in the configuration having the same diameter, and the replenishing toner can be mixed with a certain developer without applying a significantly high stress to the developer.

[Embodiment 2]
Other embodiments of the present invention will be described below with reference to FIGS. For convenience of explanation, members having the same functions as those used in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  Since the configuration of the image forming apparatus on which the developing device of the present embodiment is mounted and the basic configuration of the developing device are the same as those of the first embodiment, the developing device 2 of the first embodiment is here. Only differences from the developing device 30 of this embodiment will be described.

  7 is a cross-sectional view of the developing device 30, and FIG. 8 is a cross-sectional view taken along the line CC ′ of the developing device 2 shown in FIG. The difference from the developing device 2 of the first embodiment is that the upper surface of the developer is restricted to the upper position of the return blade 52 of the first conveying screw 112a in the first conveying path P as shown in FIG. The developer regulating member 31 is provided. The developer regulating member 31 is a plate-like member having an arch shape in the lower part, and is provided on the lower surface of the developer tank cover (ceiling surface) 115. It traps the replenishment toner conveyed on the upper surface of the developer and promotes the mixing of the replenishment toner and the developer.

  FIG. 9 shows how the replenished toner is mixed with a certain developer in the developing device 30 of the present embodiment.

  As shown in FIG. 9, in such a configuration, the first conveying screw 112a is provided with a return blade 52 that conveys the developer conveyed in the circulation direction in the opposite direction, and the return blade 52 A developer regulating member 31 is disposed on the top.

  As a result, a developer reservoir J is formed in the vicinity of the return blade 52, and the developer reservoir J causes the upper surface of the developer to swell, and the replenishment toner masses T3 and T4 conveyed while sliding on the upper surface of the developer remain as they are. Passing through is prevented, and at the same time, the replenishing toners T3 and T4 are forcibly released. Further, the reverse rotation of the return blade 52 and the developer regulating member 31 enhance the developer mixing effect, and the replenished toner is sufficiently mixed with the developer (carrier) here, so that the necessary charge amount is obtained. Can be obtained.

  Here, the developer regulating member 31 is more preferably composed of a magnet. By adopting such a configuration, a carrier in a certain developer from the past is attracted to the developer regulating member 31 made of a magnet, so that a developer reservoir having a high carrier concentration can be formed. Therefore, the replenished toner that has been transported over the developer in a lump is loosened and mixed with the developer in the developer reservoir having a high carrier concentration, so that it can be charged more effectively. Become.

  In other words, the first conveying screw 112a conveys the developer conveyed in the circulation direction in the reverse direction, and the return blade 52 that forms the developer reservoir J is disposed downstream of the toner supply port 117 in the circulation direction. The developer regulating member 31 provided perpendicularly to the circulation direction is provided on the upper portion of the return blade 52, so that the developer regulating member 31 and the return blade 52 can be used in the present invention. On the downstream side in the circulation direction of the toner replenishing port 117 in the one conveyance path P, a space blocking means for blocking the space W above the developer conveyed on the first conveyance path P is configured.

  That is, the developer reservoir J formed by the return blade 52 is blocked by the developer regulating member 31 so that the developer reservoir J is brought into contact with the developer tank cover 115 and the space W above the developer is sealed.

  Since the force of blocking the developer by the developer regulating member 31 is used, when the developer pool J cannot be brought into contact with the developer tank cover only by the action of the return blade 52, for example, the flowability of the developer is Even in such a high case, the developer reservoir J can be easily brought into contact with the developer tank cover 115 to seal the space W above the developer.

  In other words, the developer regulating member 31 only has to dam the developer pool J formed by the return blade 52, so that the upper surface of the developer is regulated without the return blade 52 being provided. Thus, the distance between the lower end of the developer regulating member and the upper surface of the developer can be secured longer than the configuration in which the upper space W of the developer is sealed, and the developer regulating member 31 is conveyed in the circulation direction. The stress applied to the developer can be reduced as much as possible by blocking the flow of the developer.

[Embodiment 3]
Other embodiments of the present invention will be described below with reference to FIGS. For convenience of explanation, members having the same functions as those used in the first and second embodiments are given the same reference numerals and explanation thereof is omitted.

  Since the configuration of the image forming apparatus on which the developing device of the present embodiment is mounted and the basic configuration of the developing device are the same as those of the first and second embodiments, here, the first and second embodiments. Only differences between the developing devices 2 and 30 and the developing device 202 of this embodiment will be described.

  The difference from the developing device 30 of the second embodiment is that, as shown in FIG. 13, the first conveying screw 212a is not provided with the return blade 52, and instead of the return blade 52, FIG. As shown in FIG. 11A and FIG. 11B, the first transport is in the upper part of the first transport path P and downstream in the circulation direction of the toner supply port 117 in the first transport path P. A movable weir 231 (upper space blocking means) for blocking the space W above the developer conveyed along the path P is provided.

  10 is a cross-sectional view of the developing device 202, and FIGS. 11A and 11B are arrow views taken along the line CC ′ of the developing device 202 shown in FIG. More specifically, FIG. 11A shows a state in which the movable weir 231 constituting the upper space blocking means blocks the developer, and FIG. 11B shows the movable weir 231 that dams the developer. The state where the stop is released is shown. In FIG. 11A and FIG. 11B, the line indicated by the alternate long and short dash line is the upper surface of the developer. FIG. 13 is an arrow diagram along line DD ′ of the developing device 202 shown in FIG.

  As shown in FIG. 10, the movable weir 231 includes a developer regulating member 231a provided perpendicular to the developer conveying direction of the first conveying screw 212a, a developer regulating member 231a, and an upper surface portion of the developer. A rotating shaft 231b that is rotatably supported on the side opposite to the contact side, and a gear 231c that transmits a rotational driving force to the rotating shaft 231b are provided. The movable weir 231 rotates the developer regulating member 231a to block and open the space W above the developer.

  The developer regulating member 231a is a plate-like member having an arch shape in the lower part, and the developer regulating member 231a is in contact with the upper surface of the developer to block the developer, and the developer tank cover (ceiling surface) ) 115 is provided so as to be in close contact with the lower surface of 115.

  The movable weir 231 traps the replenishment toner conveyed on the upper surface of the developer by sealing the space W above the developer formed between the developer tank cover 115 and the developer, and supplies the replenishment toner and the developer. It promotes mixing with.

  More specifically, the movable weir 231 reliably unravels the supply toner lump that has been transported over the upper surface of the developer by crushing it between the developer and the developer tank cover.

  FIG. 12A shows the state of the developer when the upper surface of the developer is blocked by the movable weir 231 constituting the upper space blocking means and the upper space W is blocked. Blocking by the movable weir 231 is performed in the toner replenishment mode. In the toner replenishment mode, when a toner concentration sensor (not shown) determines that the toner concentration in the developing tank 111 exceeds the lower limit of a predetermined range, the toner hopper 101 passes the toner transfer mechanism 102 through the toner transfer mechanism 102. In this mode, toner is replenished. The toner replenishment is continued intermittently or continuously until the toner concentration sensor detects that the toner concentration in the developing tank 111 has reached a predetermined reference value for ending the toner replenishment. When it is detected that the reference value has been reached, the toner replenishment mode ends.

  On the other hand, FIG. 12B shows the state of the developer when the movable dam 231 releases the developer dam and releases the upper space W. The movable weir 231 releases the clogging except during the toner replenishment mode. 12A and 12B are both arrow views along the line CC ′ of the developing device 202 shown in FIG.

  As shown in FIG. 12A, since the space W above the developer is sealed when the toner is replenished, a developer reservoir J is formed in front of the developer regulating member 231a. The supply toner lumps T3 and T4 conveyed while sliding on the upper surface of the agent are prevented from passing through as they are, and at the same time, the supply toners T3 and T4 are forcibly released. Here, the replenished toner can be sufficiently mixed with the developer (carrier) to obtain a necessary charge amount.

  Then, as shown in FIG. 12B, since the upper space W is opened except when the toner is replenished, the developer can be conveyed without applying stress to the developer.

  Further, the configuration for switching between blocking and releasing in the movable weir 231 depending on whether or not it is in the toner replenishment mode can be easily achieved by controlling the rotation of the movable weir 231 based on the detection result of the toner concentration sensor, for example. realizable.

  The timing of releasing the dam by the movable weir 231 is not the same as when the toner density sensor detects that the reference value for ending the toner supply has been reached, but the last supplied toner is developed. It is preferable to delay by the time necessary for the agent reservoir J to be sufficiently solved. Thereby, the toner replenished last can be sufficiently solved by the developer reservoir J.

  Furthermore, as shown in FIG. 12B, the movable weir 231 preferably has a configuration in which the developer regulating member 231a rotates downstream in the developer circulation direction when releasing the upper space W. .

  This is because if the developer regulating member 231a is configured to rotate upstream in the developer circulation direction when the upper space W is released, the developer regulating member 231a is developed between the developer regulating member 231a and the developer tank cover 115. This is because there is a possibility that the dam can not be released by sandwiching the agent. With the above configuration, the movable weir 231 can be opened without sandwiching the developer between the developer regulating member 231a and the developer tank cover 115.

[Embodiment 4]
Another embodiment of the present invention is described below with reference to FIG. For convenience of explanation, members having the same functions as those used in the first to third embodiments are given the same reference numerals and explanation thereof is omitted.

  Since the configuration of the image forming apparatus on which the developing device of the present embodiment is mounted and the basic configuration of the developing device are the same as those of the first to third embodiments, here, the first to third embodiments. Only the differences between the developing devices 2, 30, and 202 and the developing device 232 of the present embodiment will be described.

  The difference from the developing device 202 of the third embodiment is that, as shown in FIG. 14, the toner replenishing port is the same as the developing device 2 of the first embodiment in place of the first conveying screw 212a in the first conveying path P The first conveying screw 112 a provided with the return blade 52 is arranged downstream of the circulation direction 117. The movable weir 231 is located above the return blade 52.

  That is, it can be said that the developing device 202 of the present embodiment has a configuration in which the developer regulating member 31 in the developing device of the thirtieth embodiment is replaced with the movable weir 231.

  Thus, except for the toner replenishment mode, the developer transport is not disturbed and is the least stressed. However, in the toner replenishment mode, the replenished toner is most affected by the action of the return blade 52. It can be effectively mixed with a conventional developer and effectively triboelectrically charged.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and the embodiments can be obtained by appropriately combining the respective technical means disclosed in the above-described embodiments. The form is also included in the technical scope of the present invention.

  The developing device and the image forming apparatus of the present invention are suitable for electrophotographic multifunction devices, copying machines, printers, and facsimiles.

FIG. 5 is a schematic diagram illustrating an embodiment of the present invention, in which replenishment toner is mixed with a certain developer in the developing device. 1 is a schematic diagram illustrating an internal configuration of an image forming apparatus including a developing device according to an embodiment of the present invention. FIG. 3 is a cross-sectional view of a developing device in the image forming apparatus of FIG. 2. FIG. 4 is an arrow view along the line AA ′ of the developing device shown in FIG. 3. FIG. 4 is a B-B ′ line arrow diagram of the developing device shown in FIG. 3. FIG. 5 is an explanatory diagram illustrating a state of a joint between a conveyance blade and a return blade in a first conveyance screw provided in the developing device illustrated in FIG. 2. It is sectional drawing of the image development apparatus of other embodiment of this invention. FIG. 8 is a C-C ′ line arrow diagram of the developing device illustrated in FIG. 7. FIG. 8 is a schematic diagram illustrating how replenishment toner is mixed with a certain developer in the developing device illustrated in FIG. 7. It is sectional drawing of the image development apparatus of further another embodiment of this invention. (A) and (b) are both CC 'line arrow figures of the developing device shown in FIG. 10, and more specifically, (a) shows a state in which the movable weir blocks the developer, and (b) Indicates a state in which the movable weir 231 developer is released. (A) and (b) are both CC 'line arrow figures of the developing device shown in FIG. 10, and more specifically, (a) is that the upper surface of the developer is blocked by a movable weir, and the developer The state of the developer when the upper space of the developer is sealed is shown, and (b) is a developer when the movable weir releases the developer dam and releases the space above the developer. The state of is shown. It is a DD 'line arrow figure of the developing device shown in FIG. It is drawing which shows the structure of the image development apparatus of further another embodiment of this invention.

Explanation of symbols

2 Developing Device 30 Developing Device 31 Developer Restricting Member 52 Return Blade 100 Image Forming Device 111 Developing Tank 112a First Conveying Screw (First Conveying Member)
112b Second conveying screw (second conveying member)
113 Partition member 114 Developer carrying member 115 Developer tank cover (ceiling surface)
117 Toner supply port (supply port)
202 Developing device 231 Movable weir 231a Developer regulating member 231b Rotating shaft 231c Gear 232 Developing device P First transport path Q Second transport path T1 to T4 Replenishment toner e First communication path f Second communication path

Claims (12)

A developer tank containing a developer including toner and a carrier; first and second transport paths provided in the developer tank for transporting the developer; and provided in the first transport path. A first transport member that transports the developer in a predetermined direction while stirring the developer in the first transport path, and the predetermined direction while stirring the developer in the second transport path provided in the second transport path. A second conveying member that conveys in the opposite direction, first and second communicating paths that communicate the ends of the first and second conveying paths on both sides in the longitudinal direction, and the developer in the second conveying path. A developer carrying member that carries the toner contained in the developer to the photoreceptor, and a developer tank cover that covers the upper surface of the developer conveyed in the first conveyance path, leaving a space in the upper part; A toner replenishing port for replenishing toner to the first transport path, Image agent, wherein the first conveyance path, the first communication path, a second conveying path, and a second communication path in the developing device is transported to circulate in this order,
An upper space blocking means for blocking an upper space of the developer conveyed through the first conveyance path is provided on the downstream side in the circulation direction of the toner supply port in the first conveyance path. Development device. The first transport member includes a return blade that transports the developer transported in the circulation direction in the reverse direction to form a developer reservoir on the downstream side in the circulation direction of the toner supply port.
The upper space sealing means includes the return blade provided in the first conveying member, and the developer reservoir formed by the return blade is brought into contact with the developer tank cover to seal the upper space. The developing device according to claim 1, wherein:   The developing device according to claim 1, wherein the return blade is a spiral screw auger that conveys the developer in a direction opposite to a circulation direction.   The said 1st conveyance member is equipped with the helical conveyance blade | wing formed continuously with the said return blade | wing, and conveys the said developer to a circulation direction, Any one of Claims 1-3 characterized by the above-mentioned. The developing device described.   The developing device according to claim 4, wherein a diameter of the return blade is smaller than a diameter of the transport blade of the first transport member.   The developing device according to claim 1, wherein a developer regulating member that regulates an upper surface of the developer is provided on an upper portion of the return blade. The carrier is a magnetic carrier;
The developing device according to claim 6, wherein the developer regulating member is made of a magnet. The upper space blocking means contacts the upper surface portion of the developer transported in the first transport path provided downstream in the circulation direction of the toner supply port in the first transport path. It consists of a movable weir that dams the agent,
The developing device according to claim 1, wherein the movable weir blocks the upper space during the toner replenishment mode and opens the upper space except during the toner replenishment mode.   The movable weir is provided perpendicular to the circulation direction, the developer regulating member that contacts the upper surface portion of the developer, and the side that contacts the developer regulating member with the upper surface portion of the developer; Comprises a rotating shaft that is rotatably supported on the opposite side, and a gear that transmits a rotational driving force to the rotating shaft, and the developer regulating member is rotated to block and open the upper space. The developing device according to claim 8, wherein:   The developing device according to claim 9, wherein the developer restricting member rotates about the rotation shaft to the downstream side in the circulation direction to open the upper space. The first transport member includes a return blade that transports the developer transported in the circulation direction in the reverse direction to form a developer reservoir on the downstream side in the circulation direction of the toner supply port.
On the upper part of the return blade, a developer regulating member provided perpendicular to the circulation direction is provided,
The upper space blocking means includes the developer regulating member and the return blade provided in the first transport member, and blocks the developer pool formed by the return blade with the developer regulating member. The developing device according to claim 1, wherein the developer reservoir is brought into contact with the developer tank cover to seal the upper space.   An image forming apparatus of an electrophotographic system, comprising the developing device according to claim 1.

Images