JP6068276B2 - Developing device, process cartridge, and image forming apparatus - Google Patents

Description

  The present invention relates to a developing device, a process cartridge using the developing device, and an image forming apparatus.

  An image forming apparatus that forms an image using a developing device that contains a two-component developer (hereinafter referred to as a “developer”) containing toner and a carrier has the toner fixed on a recording sheet during image formation. Although it is gradually consumed, the carrier is hardly consumed and remains in the developing device. Therefore, if only the toner is supplied to the developing device according to the amount of consumed toner and the carrier is repeatedly used, the carrier may be worn out and the image quality of the formed image may be deteriorated.

  In view of this, it is known to replace the developer with a new one when the accumulated usage time reaches a predetermined time, or to gradually replenish the developer and discharge the deteriorated carrier to the outside.

  As a developing device such as the latter, a developing tank for storing the developer, a developing roller for supplying the developer to the image carrier (photoconductor), and a developer in the developing tank for conveying the developer to the developing roller. An auger screw having a spiral blade, a discharge port for discharging the developer to the outside at a predetermined height on the side wall of the developing tank, and a developer conveyed by the auger screw at the lower end of the discharge port Those that are discharged to the outside by an amount exceeding the limit are known (see, for example, Patent Documents 1 and 2).

  In such a developing device, the toner density in the developing tank is controlled according to the printing rate of the image to be formed. That is, when an image with a high printing rate (high coverage image) is formed, the amount of developer supplied from the replenishing device connected to the developing device is increased so that the toner density in the developing tank is increased. Controlled. On the other hand, when an image with a low printing rate (low coverage image) is to be formed, the amount of developer supplied from the replenishing device is controlled to be small so that the toner density in the developing tank is low.

JP 2009-58649 A JP 2009-63991 A

  However, in the above-described developing device, when a large amount of low coverage image is printed, the amount of developer supplied from the replenishing device to the developing tank is small, so that the amount of developer in the developing tank may gradually decrease. is there. When the developer amount is reduced in this way, a part of the auger screw is exposed from the developer surface of the developer, and the developer is likely to be scattered by the rotation of the auger screw. There is a problem that the amount of the developer is significantly reduced and the image quality of the image to be formed may deteriorate.

  Therefore, there is a technical problem to be solved in order to suppress the excessive discharge of the developer due to the scattering of the developer due to the rotation of the spiral blade and maintain the developer amount suitable for image printing. The present invention aims to solve this problem.

  The present invention is proposed in order to achieve the above object, and the invention according to claim 1 is a developing device for developing an electrostatic latent image formed on an image carrier, and includes a toner and a carrier. A developer tank provided with a discharge port for discharging excess developer when the developer surface exceeds a predetermined height in the vertical direction, and the developer in a predetermined transport direction. A conveying unit provided with a conveying spiral blade and circulating the developer in the developing tank; and disposed between the conveying unit and the discharge port in the vertical direction and from upstream to downstream in the conveying direction. A developing device is provided that includes an anti-scattering inclined plate inclined downward in the vertical direction toward the outside, and an external discharge suppressing unit that suppresses external discharge of the developer due to rotation of the spiral blade.

  According to this configuration, since the scattering suppression inclined plate is provided between the conveying unit and the discharge port in the vertical direction of the developing device, the amount of the developer is temporarily reduced, and the developer surface of the developer is lowered. Even if a part of the spiral blade is exposed from the surface of the developer and the spiral blade causes the developer to scatter, development by rotation of the spiral blade is performed in order to dampen the scattered developer. Excessive external discharge of the developer due to the scattering of the agent can be suppressed.

  Furthermore, since the scattering suppression inclined plate is inclined downward in the vertical direction from the upstream side to the downstream side in the transport direction, a part of the scattering suppression inclined plate is obtained during normal operation in which a sufficient amount of developer is secured. Even if the developer is immersed in the developer, the developer is gently transported from the upstream side to the downstream side in the transport direction without receiving excessive frictional resistance along the scattering suppression inclined plate. The suppression inclined plate can suppress excessive discharge of the developer due to the scattering of the developer due to the rotation of the spiral blade when the amount of the developer is reduced without impairing the fluidity of the developer during normal operation. .

  According to a second aspect of the invention, in addition to the configuration of the first aspect of the invention, the external discharge suppression means is extended along the transport direction on the upstream side of the transport direction with respect to the scattering suppression inclined plate. A developing device is provided that includes an upstream horizontal plate, and an upstream pulsation stopping plate that is suspended upward in the vertical direction with a gap from the upstream horizontal plate.

  According to this configuration, when the upstream side horizontal plate and the upstream side pulsation stop plate are provided to face each other with a gap, when the developer surface of the developer is lower than the upstream side horizontal plate, The developer carried on the upstream horizontal plate closes the gap between the upstream horizontal plate and the upstream pulsation stop plate, and the scattering suppression inclined plate, the upstream horizontal plate, and the upstream horizontal plate Since the upstream side is covered, it is possible to further suppress the external discharge of the developer due to the scattering of the developer even if the spiral blades scatter the developer.

  Further, even when the developer pulsates and the developer surface on the upstream side in the transport direction with respect to the discharge port becomes locally high in the vertical direction, the upstream pulsation stop plate is Damping the developer waved higher than the lower end of the pulsation stop plate. Thereby, it is possible to suppress the developer from being excessively discharged from the discharge port due to the pulsation of the developer.

  According to a third aspect of the invention, in addition to the configuration of the first or second aspect of the invention, the external discharge suppression means is suspended along the vertical direction on the downstream side of the transport direction with respect to the discharge port. Provided is a developing device including a downstream pulsation stopping plate.

  According to this configuration, even when the developer is reflected in the developing tank and the developer surface on the downstream side in the transport direction with respect to the discharge port is locally high in the vertical direction, the downstream side The pulsation stop plate dampens the undulating developer higher than the lower end of the downstream pulsation stop plate. Thereby, it is possible to further suppress the developer from being excessively discharged from the discharge port due to the reflection of the developer in the developing tank.

  According to a fourth aspect of the present invention, in addition to the configuration of the first aspect of the present invention, the external discharge suppression means is disposed to face the discharge port and extends along the vertical direction. A developing device having an extended rotation pulsation stop plate is provided.

  According to this configuration, even when the developer pulsates and the developer surface becomes locally higher in the rotational direction of the spiral blade, the rotational pulsation stop plate positioned so as to face the discharge port However, it clogs the developer that has undulated higher than the lower end of the rotational pulsation stop plate. Thereby, it is possible to suppress the developer from being excessively discharged from the discharge port due to the pulsation of the developer.

  According to a fifth aspect of the present invention, there is provided an image forming apparatus comprising the developing device according to any one of the first to fourth aspects.

  According to this configuration, the developer is prevented from being inadvertently discharged from the developing tank, and the developer amount in the developing tank is suppressed from excessively decreasing. An image can be formed.

  According to a sixth aspect of the present invention, there is provided a photosensitive drum on which an electrostatic latent image is formed, a charging device for charging the surface of the photosensitive drum, and the electrostatic latent image on the surface of the photosensitive drum as a toner image. 5. A process cartridge comprising: the developing device according to claim 1 for developing; and a cleaning unit that removes toner remaining on the surface of the photosensitive drum and cleans the surface of the photosensitive drum. To do.

  According to this configuration, it is possible to form a high-quality image during development in order to suppress a decrease in the developer amount in the developing tank.

  According to a seventh aspect of the present invention, there is provided the process cartridge according to the sixth aspect, an exposure device that forms an electrostatic latent image on the surface of the photosensitive drum, a replenishing device that replenishes the developer to the developing device, An image forming apparatus is provided that includes a transfer device that transfers a toner image formed on the surface of a photosensitive drum to a recording medium, and a fixing device that fixes the transferred toner image to the recording medium.

  According to this configuration, the developer is prevented from being inadvertently discharged from the developing tank, and the developer amount in the developing tank is suppressed from excessively decreasing. An image can be formed.

  According to the present invention, it is possible to maintain a developer amount suitable for image printing in a developing tank and form a high-quality image during development. Furthermore, the fluidity of the developer can be maintained even during normal operation in which a sufficient amount of developer is ensured.

1 is a schematic diagram illustrating a configuration of an image forming apparatus 100. FIG. The schematic diagram which shows the structure of the replenishment apparatus 4. FIG. III-III sectional view taken on the line shown in FIG. FIG. 4 is a vertical sectional view of the developing device 200 taken along line IV-IV in FIG. 1. FIG. 5 is a cross-sectional view in the short-side direction of the developing device 200 taken along line VV shown in FIG. 4. FIG. 6 is a cross-sectional view in the short-side direction of the developing device 200 taken along the line VI-VI shown in FIG. 4. (A) The longitudinal direction sectional view of the image development apparatus 200 in the VII-VII line shown in FIG. And (b) The figure which looked at the image development apparatus 200 from the arrow B in FIG. The perspective view which shows the external discharge | emission suppression means 250. FIG. The figure which shows the state which dams up the developer G which the scattering suppression inclination board 251 scattered. The figure which shows the state in which the developer G was carry | supported on the upstream horizontal board 252. FIG. The figure which shows the state which clogs the developer G which the upstream pulsation stop plate 253 pulsates. The figure which shows the state which clogs the developer G with which the downstream pulsation suppression board 254 pulsates. The figure which shows the state which dams the developer G to which the rotation pulsation suppression board 255 pulsates.

  The developing device according to the present invention achieves the object of suppressing an excessive external discharge of the developer due to the scattering of the developer due to the rotation of the spiral blade and maintaining a developer amount suitable for image printing. A developing device for developing an electrostatic latent image formed on an image carrier, which contains a developer including toner and a carrier, and the developer surface of the developer exceeds a predetermined height in the vertical direction. A developer tank having a discharge port for discharging excess developer, a spiral blade for transporting the developer in a predetermined transport direction, a transport means for circulating the developer in the developer tank, and a transport in the vertical direction A scattering suppression inclined plate disposed between the means and the discharge port and inclined downward in the vertical direction from the upstream side to the downstream side in the transport direction is provided to suppress external discharge of the developer due to rotation of the spiral blade. And a developing device equipped with external discharge suppression means. It was.

  An embodiment of a developing device 200 according to the present invention and an image forming apparatus 100 using the developing device 200 will be described with reference to FIGS.

  The image forming apparatus 100 according to this embodiment is a full-color printer that can form a color image on a sheet-like recording medium (recording paper) according to image data transmitted from the outside.

As shown in FIG. 1, an image forming apparatus 100 includes a photosensitive drum 1 on which an electrostatic latent image is formed, a charging roller 2 as a charging device that charges the surface of the photosensitive drum 1, and a photosensitive drum. An exposure device 3 that forms an electrostatic latent image on the surface of the photosensitive drum 1, a developing device 200 that develops the electrostatic latent image on the surface of the photosensitive drum 1 into a toner image, and a two-component developer (hereinafter referred to as toner and carrier). Simply referred to as “developer G”), a replenishing device 4 for replenishing the developing device 200, a transfer device 5 for transferring a toner image formed on the surface of the photosensitive drum 1 to a recording medium, and a recording of the transferred toner image. A fixing device 6 for fixing to a medium and a cleaning unit 7 for removing toner remaining on the surface of the photosensitive drum 1 are provided.
The photosensitive drum 1, the charging roller 2, the developing device 200, and the cleaning unit 7 are integrated to form a process cartridge 300.

  The image forming apparatus 100 corresponds to the image information of each color of black (b), cyan (c), magenta (m), and yellow (y) included in the color image information, and the replenishment device 4 and an intermediate described later. Four transfer rollers 54 and four process cartridges 300 (that is, the photosensitive drum 1, the charging roller 2, the developing device 200, and the cleaning unit 7) are provided. In the present embodiment, when distinguishing each member provided by four according to each color, an alphabet representing each color is added to the end of a number representing each member as a reference symbol, and each member is generically named. In this case, only numerals representing the respective members are used as reference symbols.

  The process cartridge 300 is detachably attached to the image forming apparatus 100, and is replaced with a new one as the developer G deteriorates.

  The photosensitive drum 1 is supported in a counterclockwise direction on the paper surface of FIG. 1 by a drive unit (not shown), and is formed on a cylindrical conductive substrate (not shown) and the surface of the conductive substrate to conduct light conduction. And a photoconductive layer made of a material exhibiting properties.

  The charging roller 2 is juxtaposed in a state close to the photosensitive drum 1. The charging roller 2 only needs to charge the surface of the photosensitive drum 1 to a predetermined polarity and potential, and the photosensitive drum 1 such as a brush type charging device or a roller type charging device is separated from the charging roller 2. Either a non-contact charging method or a contact charging method in which the photosensitive drum 1 such as a corona discharge device or an ion generating device and the charging roller 2 are in contact with each other may be used. The charging roller 2 is disposed closer to the photosensitive drum 1 than the developing device 200 and a cleaning unit 7 described later. As a result, it is possible to reliably prevent the charging failure of the photosensitive drum 2.

  The exposure device 3 irradiates each surface of the photosensitive drums 1b, 1c, 1m, and 1y in a charged state with laser light corresponding to the image information of each color. As a result, electrostatic latent images corresponding to the image information of the respective colors are formed on the surfaces of the photosensitive drums 1b, 1c, 1m, and 1y uniformly charged by the charging roller 2.

  The developing device 200 supplies toner to the electrostatic latent image formed on the surface of the photosensitive drum 1, so that a toner image is formed on the surface of the photosensitive drum 1. Details of the developing device 200 will be described later.

The replenishing device 4 is disposed above the developing device 200. As shown in FIGS. 2 and 3, the replenishing device 4 includes a developer supply pipe 41 that extends in a cylindrical shape in the vertical direction H ′ (the vertical direction in FIG. 1) of the image forming apparatus 100 and is connected to the developing device 200. A storage container 42 for storing the unused developer G, a pumping member 43 for pumping up the developer G in the storage container 42, a discharge container 44 having a discharge port 44a for discharging the developer G, and a discharge container And a discharge member 45 that conveys the developer G in 42 to the discharge port by the discharge blade 45a. The replenishing device 4 supplies the toner and the carrier to the developing device 200 at the same time, but may be configured to supply the toner or the carrier independently.
As a result, the unused developer G stored in the storage container 42 is pushed out to the discharge port 44 a by the discharge blade 45 a and supplied to the developing device 200 via the developer supply pipe 41.

The transfer device 5 includes an endless intermediate transfer belt 51 disposed above the photosensitive drum 1 in the vertical direction H ′, a drive roller 52 that moves the intermediate transfer belt 51 in the direction of the arrow in FIG. A driven roller 53 that stretches the intermediate transfer belt 51, an intermediate transfer roller 54 that is pressed against the photosensitive drum 1 through the intermediate transfer belt 51 and applied with a transfer bias, and a driving roller through the intermediate transfer belt 51. And a transfer roller 55 that is pressed against 52.
As a result, the toner images of the respective colors formed on the photosensitive drums 1y, 1m, 1c, and 1b are respectively transferred to the intermediate transfer rollers 54y, 54m, 54c, to which a transfer bias having a polarity opposite to the charging polarity of each toner image is applied. A full-color toner image is formed by being sequentially superimposed and transferred in this order on the intermediate transfer belt 51 by 54b. The full-color toner image carried on the intermediate transfer belt 51 is transferred to a recording medium fed from a recording medium supply device 8 described later in a pressure contact area between the driving roller 52 and the transfer roller 55.

  The recording medium supply device 8 includes a paper feed tray 81 that stores a recording medium to which a toner image is transferred, a pickup roller 82 that takes out the recording medium one by one from the paper feed tray 81, and a recording that is taken out from the paper feed tray 81. A conveyance roller 83 that conveys the medium to a pressure contact area between the drive roller 52 and the transfer roller 55 is provided. Examples of the recording medium include plain paper, color copy paper, overhead projector sheet, and postcard.

  The fixing device 6 that fixes the toner image transferred to the recording medium includes a heating roller 61 controlled to a predetermined fixing temperature and a pressure roller 62 that presses the heating roller 61. As the recording medium passes between the heating roller 61 and the pressure roller 62 in a heated state, the toner constituting the toner image is melted and fixed on the recording medium.

  The discharge device 9 that discharges the recording medium on which the toner is fixed is transported from the transport roller 91 and a pair of transport rollers 91 that sandwich the recording medium transported in the vertical direction H ′ from the fixing device 6 and transport it in the horizontal direction. A pair of discharge rollers 92 that sandwich the recording medium and discharge the recording medium to the outside, and a discharge tray 93 that receives the recording medium discharged from the discharge roller 92.

  The cleaning unit 7 cleans the surface of the photosensitive drum 1 by removing the toner remaining on the surface of the photosensitive drum 1 after the toner image on the surface of the photosensitive drum is transferred to the intermediate transfer belt 51. .

  The image forming apparatus 1 further includes a control unit (not shown). The control unit includes a storage unit that receives input information from the outside, an arithmetic unit that extracts various data (image formation commands, detection results, image information, etc.) and various processing programs written in the storage unit, and performs various determinations; A control unit that controls the operation by transmitting a control signal to each device provided in the image forming apparatus 1 according to the determination result of the calculation unit.

  As the storage unit, those commonly used in this field such as ROM, RAM, HDD and the like can be used, and various setting values via an operation panel (not shown) arranged in the image forming apparatus, and various places inside the image forming apparatus can be used. A detection result of a sensor (not shown) disposed, image information input from an external device, and the like are input. The external device may be any electrical or electronic device that can form and acquire image information and can be electrically connected to the image forming apparatus. For example, a computer, a digital camera, a television receiver, a video recorder A DVD recorder, an HDDVD (High-Definition Digital Versatile Disc) recorder, a Blu-ray disc recorder, a facsimile device, a portable terminal device, or the like may be used.

  Next, the developing device 200 according to the present invention will be described with reference to FIGS.

  The developing device 200 includes a developing tank 210 that stores the developer G, a first conveying member 220 and a second conveying member 230 that serve as conveying means rotatably provided in the developing tank 210, and the developer G on the surface. A developing roller 240 that carries the toner to the photosensitive drum 1 and carries an external discharge suppression unit 250 that suppresses external discharge due to scattering of the developer G is provided.

The developing tank 210 includes a bottom portion 211, a side wall portion 212 erected from the periphery of the bottom portion 211, a partition wall portion 213 extending in the longitudinal direction L of the developing tub 210 and erected from the vicinity of the center of the bottom portion 211, and a side wall portion. And a developing cover 214 which is detachably mounted on 212.
As a specific material of the developing tank 210, for example, a resin material such as polyethylene, polypropylene, high impact polystyrene, and ABS resin is used.

  The side wall 212 is the vertical direction H of the developing tank 210 that coincides with the vertical direction H ′ of the image forming apparatus 100, that is, the direction perpendicular to the bottom 211 and the development cover 214 facing upward with respect to the bottom 211. , A discharge port 212a for discharging a part of the developer G to a waste developer transport container 260 described later when the surface of the developer G in the developing tank 210 exceeds a predetermined height is provided.

  The partition wall 213 includes a first transport path A1 extending along the longitudinal direction L of the developing device 200 in a space R surrounded by the bottom portion 211 and the side wall section 212, and a second transport path provided in parallel with the first transport path A1. The first communication path A3 that connects the conveyance path A2, the first conveyance path A1 and the second conveyance path A2 on one end side in the longitudinal direction L, and the first conveyance path A1 and the second conveyance path A2 in the longitudinal direction. It is partitioned off into a second communication path A4 communicating with the other end of L.

  As shown in FIGS. 4 and 5, the developing cover 214 is replenished via a supply port 214a formed in the developing cover 214 so as to be positioned above the first transport path A1 and the second communication path A4. 4 developer supply pipe 41. Thus, the developer G accommodated in the replenishing device 4 is supplied into the developing tank 210 through the developer supply pipe 41.

As shown in FIG. 4, the first transport member 220 is provided in the first transport path A <b> 1 along the longitudinal direction L. The first conveying member 220 conveys the developer G in the developing tank 200 from the other end side in the longitudinal direction L toward the one end side. Hereinafter, the conveyance direction of the developer G by the first conveyance member 220 is referred to as a first conveyance direction D1.
The first conveying member 220 includes a cylindrical first rotary shaft member 221 extending in the longitudinal direction L, a first spiral blade 222 as a spiral blade provided on the peripheral surface of the first rotary shaft member 221, and not illustrated. And a first gear 223 that rotates the first rotating shaft member 221 around the axis by a rotational driving source such as a motor, and is formed in an auger screw shape. The first rotating shaft member 221 is rotatably supported around an axis line by a bearing (not shown) fixed to the side wall portion 212.

  The first spiral blade 222 is a peripheral surface of the first rotating shaft member 221 across the first transport direction D1 except for a region located below the vertical direction H with respect to the discharge port 212a formed in the side wall portion 212. And is composed of an upstream spiral blade 222a provided on the upstream side in the first transport direction D1 and a downstream spiral blade 222b provided on the downstream side in the first transport direction D1. Yes. Although the first spiral blade 222 is not disposed in the region located below the discharge port 212a, a spiral blade having a smaller diameter than the first spiral blade 222a may be provided.

The 2nd conveyance member 230 is provided over the longitudinal direction L in 2nd conveyance path A2. The second conveying member 230 conveys the developer G in the developing tank 200 from one end side in the longitudinal direction L toward the other end side. Hereinafter, the conveyance direction of the developer G by the second conveyance member 230 is referred to as a second conveyance direction D2.
The second transport member 230 includes a cylindrical second rotary shaft member 231 extending in the longitudinal direction L, a second spiral blade 232 as a spiral blade provided on the peripheral surface of the second rotary shaft member 231, and not illustrated. And a second gear 233 that rotates the second rotary shaft member 231 about the axis by a rotational drive source such as a motor, and is formed in an auger screw shape. The second rotary shaft member 230 is supported by a bearing (not shown) fixed to the side wall portion 212 so as to be rotatable around the axis.

  The second spiral blade 232 is continuously provided on the peripheral surface of the second rotating shaft member 231 over the second transport direction D2.

  The 1st conveyance member 220 and the 2nd conveyance member 230 may be formed with resin materials, such as polyethylene, a polypropylene, high impact polystyrene, ABS resin, polyacetal, for example.

  The first rotating shaft member 221 and the second rotating shaft member 232 may be formed of a metal material such as SUS or SUM. It is preferable that the first rotating shaft member 221 and the first spiral blade 222 or the second rotating shaft member 231 and the second spiral blade 232 are integrally formed of the same material.

  The first spiral blade 222 and the second spiral blade 232 have a multiple spiral structure. Here, the “multi-spiral structure” means that the plurality of spiral blades are arranged at the same position in the axial direction of the first rotating shaft member 221 or the second rotating shaft member 231 and at different positions in the circumferential direction. 221 or the structure which surrounds the surrounding surface of the 2nd rotating shaft member 231 is pointed out. The first spiral blade 222 and the second spiral blade 232 have a double spiral structure including two spiral blades, but may have a triple or more spiral structure.

  The developer G supplied into the developing device 200 from the replenishing device 4 through the supply port 214a by the first conveying member 220 and the second conveying member 230 described above is rotated counterclockwise in FIG. It circulates to. That is, the developer G is transported in the first transport path A1 from the upstream side to the downstream side in the first transport direction D1 by the first transport member 220, flows into the second transport path A2 through the first communication path A3, The second transport path A2 is transported from the upstream side in the second transport direction to the downstream side by the second transport member 230, and returns to the upstream side of the first transport path A1 through the second communication path A4. Further, while the developer G circulates in the developing tank 200, the developer G overflowing from the discharge port 212 a is discharged to the waste developer transport container 260.

  As shown in FIGS. 5 and 6, the developing roller 240 is provided over both ends of an opening provided above the second transport path A <b> 2 and facing the photosensitive drum 1. A power supply (not shown) is connected to the developing roller 240 so that a developing bias voltage is applied. As a result, the toner carried on the developing roller 240 can move to the photosensitive drum 1 in the vicinity of the photosensitive drum 1 by electrostatic force due to the developing bias voltage.

  As shown in FIG. 5, a toner concentration detection sensor 270 is provided at the bottom of the developing tank 200 so that the sensor surface is exposed to the second transport path A2. The toner concentration detection sensor 270 may be any of general toner concentration detection sensors such as a transmitted light detection sensor, a reflected light detection sensor, and a magnetic permeability detection sensor, and a magnetic permeability detection sensor is particularly preferable.

  The toner concentration detection sensor 270 is electrically connected to a toner concentration control unit (not shown). The toner concentration control unit determines whether or not the toner concentration detection result by the toner concentration detection sensor is lower than a predetermined set value, and when it is determined to be low, the rotational drive source that rotates the discharge member 45 of the replenishing device 4 The developer G is supplied into the developing tank 200 by sending a control signal to the discharge tank 45 and rotating the discharge member 45.

  Further, as shown in FIGS. 5 and 6, a rectangular plate-shaped doctor blade 280 is provided on the side wall 212 of the developing tank 200. The doctor blade 280 is extended along the longitudinal direction L. The doctor blade 280 has a lower end portion fixed to the developing tank 200 and an upper end portion provided at a distance from the surface of the developing roller 240. For specific materials of the doctor blade 280, stainless steel, aluminum, synthetic resin, or the like is used.

  As shown in FIGS. 7A and 7B, the waste developer transport container 260 is constituted by a waste developer transport member 261 rotatably provided inside the waste developer transport container 260. It flows into a waste developer collecting container (not shown) communicated with 260 through a discharge port 260a. The waste developer collection container is detachable from the waste developer transport container, and the waste developer can be collected by appropriately replacing the waste developer collection container.

  As shown in FIG. 8, the external discharge suppression unit 250 includes a scattering suppression inclined plate 251 formed to be inclined downward in the vertical direction H from the upstream side to the downstream side in the first transport direction D1, and the scattering suppression inclination. An upstream horizontal plate 252 that extends from the front end of the plate 251 toward the upstream side in the first transport direction D1 and a vertical gap H from the developing cover 214 in the vertical direction H with a clearance r between the upstream horizontal plate 252 and the upstream horizontal plate 252. In the vertical direction H and the short direction W from the developing cover 214 on the downstream side in the first transport direction D1 with respect to the upstream side pulsation stop plate 253 suspended in the direction H and the short direction W, and the scattering suppression inclined plate 251. A downstream pulsation restricting plate 254 that is suspended, and a rotational pulsation restricting plate 255 that extends along the first conveying direction D1 across the upstream pulsation restricting plate 253 and the downstream pulsation restricting plate 255 are provided. Yes.

  As shown in FIG. 9, in the longitudinal direction L, the external discharge restraining means 250 has a discharge port 212a with an upstream pulsation stop plate 253 and a downstream pulsation stop plate 254 upstream and downstream in the first transport direction D1. Are attached to the side wall 212 so as to be surrounded.

  In addition, the external discharge suppression unit 250 is configured such that, in the vertical direction H, the side wall portion 212 so that the upper surfaces of the upstream pulsation restricting plate 253, the downstream pulsation restricting plate 254, and the rotational pulsation restricting plate 255 Is positioned.

  The scattering suppression inclined plate 251 is disposed between the first transport member 220 and the discharge port 212a in the vertical direction H. Specifically, the scattering suppression inclined plate 251 is disposed so as to cross between the rear end lower portion 222c of the upstream spiral blade 222a and the discharge port 212a.

  As a result, the developer surface of the developer G is lowered and a part of the upstream spiral blade 222a is exposed from the agent surface, and the upstream spiral blade 222a scatters the developer G as the first conveying member 220 rotates. Even so, because the developer G on which the scattering suppression inclined plate 251 is scattered is prevented, excessive discharge of the developer G due to the scattering of the developer G can be suppressed.

  Further, the scattering suppression inclined plate 251 is inclined downward in the vertical direction H from the upstream side to the downstream side in the first transport direction D1, so that the surface of the developer G rises and the scattering suppressing inclined plate 251 Even when a part of the developer G is submerged in the developer G, the developer G is gently moved along the scattering suppression inclined plate 251 inclined without receiving excessive frictional resistance from the lower surface 251s of the scattering suppressing inclined plate 251. Since the developer G is transported to the downstream side in the transport direction D1, the developer G caused by the developer G being scattered when the developer G is lowered without impairing the fluidity of the developer G during normal operation. Excessive external discharge can be suppressed.

  As shown in FIG. 10, the upstream side horizontal plate 252 has a tip formed at an acute angle. Thereby, the resistance when the developer G transported along the first transport direction D1 hits the upstream horizontal plate 252 is reduced, and deterioration of the developer G can be suppressed.

  The upstream pulsation restricting plate 253 is formed to be approximately half the height of the rotational pulsation restricting plate 255, and a clearance r through which the developer G is passed is secured between the upstream pulsation restricting plate 255 and the upstream horizontal plate 252.

  As a result, when the surface of the developer G is lowered, the developer G carried on the upstream horizontal plate 252 closes the gap r between the upstream horizontal plate 252 and the upstream pulsation stop plate 253, and the discharge port 212a is surrounded by the scattering suppression inclined plate 251, the upstream horizontal plate 252 and the upstream pulsation stopping plate 253 on the upstream side in the first transport direction D1. For this reason, even when the upstream spiral blade 221 scatters the developer G, it is possible to further suppress external discharge caused by the scatter of the developer G.

  Further, as shown in FIG. 11, even when the developer G pulsates and the surface of the developer G undulates locally in the vertical direction H, the upstream pulsation stop plate 253 is not In order to block the developer G that has undulated higher than the lower end of the pulsation stop plate 253, the developer G is excessively discharged from the discharge port 212a due to the pulsation of the developer G in the vertical direction H of the developing tank 220. Can be suppressed.

  As shown in FIG. 12, the downstream pulsation restraining plate 254 is provided in the vicinity of the rear end of the discharge port 212a on the downstream side of the discharge port 212a in the first transport direction D1.

  As a result, the developer G transported to the downstream side of the first transport member 220 by the downstream spiral blade 222b is reflected by the side wall portion 212 and flows backward to the upstream side, and downstream of the discharge port 212a in the first transport direction D1. Even when the surface of the developer G on the side undulates locally in the vertical direction H, the downstream pulsation stop plate 254 blocks the developer G higher than the lower end of the downstream pulsation stop plate 254. Therefore, it is possible to further suppress the developer G reflected by the side wall portion 212 of the developing tank 200 from being excessively discharged from the discharge port 212a.

  As shown in FIG. 13, the rotation pulsation stopping plate 255 is extended in the longitudinal direction L longer than the discharge port 212a. The lower end of the rotation pulsation stop plate 255 extends downward in the vertical direction H from the lower end of the discharge port 212a.

  As a result, even when the developer G pulsates and the developer G undulates locally in the rotation direction of the first conveying member 220, the rotation pulsation stop plate 255 Since the developer G undulating higher than the lower end is stopped, it is possible to further suppress the developer G from being excessively discharged from the discharge port 212a due to the pulsation of the developer G.

  As described above, the developing device 200 does not deteriorate the fluidity of the developer G, and the scattering suppression inclined plate 251 blocks the developer G scattered by the rotation of the upstream spiral blade 222a, and the developer G In order to suppress excessive external discharge, a developer amount suitable for image printing can be maintained.

  Furthermore, the image forming apparatus 100 using the developing device 200 can stably form a high-quality image.

  Further, the scattering suppressing inclined plate 251 is formed between the side wall portion 212 and the rotation pulsation restricting plate 255 in the short direction W of the developing tank 200, but is scattered by the rotation of the first conveying member 220. As long as the external discharge of the developer G can be suppressed, the length in the short direction W of the scattering suppression inclined plate 251 may be any.

  Further, the specific inclination angle of the scattering suppression inclined plate 251 is any angle as long as it suppresses the external discharge due to the scattering of the developer G and the fluidity of the developer G does not deteriorate excessively. It doesn't matter.

  Moreover, it is preferable that the scattering suppression inclined plate 251 extends the rear end of the scattering suppression inclined plate 251 to such an extent that the rotation operation of the first spiral member 221 is not hindered. Thereby, the external discharge | emission by scattering of the developer G can be suppressed reliably.

  The image forming apparatus 100 is a color printer, as long as it can form a multicolor or single color image on a recording medium even in accordance with image data transmitted from the outside and / or image data read from a document by a scanner. It may be a copier, a facsimile machine, or a multifunction machine having these functions.

  The present invention can be variously modified without departing from the spirit of the present invention, and the present invention naturally extends to the modified ones.

DESCRIPTION OF SYMBOLS 1 ... Photosensitive drum 2 ... Charging roller (charging device)
DESCRIPTION OF SYMBOLS 3 ... Exposure apparatus 4 ... Replenishment apparatus 5 ... Transfer apparatus 6 ... Fixing apparatus 7 ... Cleaning unit 8 ... Recording medium supply apparatus 9 ... Discharge apparatus 100 ... Image formation Device 200... Developing device 210... Developing tank 211... Bottom portion 212... Side wall portion 212 a. (Conveying means)
221 ... 1st rotating shaft member 222 ... 1st spiral blade (spiral blade)
222a, upstream spiral blade 222b, downstream spiral blade 230, second transport member (transport means)
231 ... 2nd rotating shaft member 232 ... 2nd spiral blade (spiral blade)
240 ... developing roller 250 ... external discharge suppressing means 251 ... scattering suppressing inclined plate 252 ... upstream horizontal plate 253 ... upstream pulsation stop plate 254 ... downstream pulsation stop plate 255 ..Rotation pulsation stop plate 300 ... Process cartridge G ... Developer

Claims (7)

A developing device for developing an electrostatic latent image formed on an image carrier,
A developer tank containing a developer containing toner and a carrier, and having a discharge port for discharging excess developer when the developer surface of the developer exceeds a predetermined height in the vertical direction;
A conveying unit that includes a spiral blade that conveys the developer in a predetermined conveying direction, and circulates the developer in the developing tank;
A scattering suppression inclined plate disposed between the conveying means and the discharge port in the vertical direction and inclined downward in the vertical direction from the upstream side to the downstream side in the conveying direction; An external discharge suppression means for suppressing external discharge of the developer by rotation;
A developing device comprising:   The external discharge suppression means includes an upstream horizontal plate extended along the transport direction on the upstream side of the transport direction with respect to the scattering suppression inclined plate, and a gap between the upstream horizontal plate and the upstream horizontal plate. The developing device according to claim 1, further comprising an upstream pulsation stop plate vertically suspended in a vertical direction.   The said external discharge | emission suppression means is provided with the downstream pulsation suppression board suspended along the said vertical direction in the downstream of the said conveyance direction with respect to the said discharge port. Development device.   The external discharge suppression means includes a rotation pulsation stop plate disposed opposite to the discharge port and extending along the vertical direction. The developing device according to item.   An image forming apparatus comprising the developing device according to claim 1. A photosensitive drum having an electrostatic latent image formed on the surface;
A charging device for charging the surface of the photosensitive drum;
The developing device according to claim 1, wherein the electrostatic latent image on the surface of the photosensitive drum is developed into a toner image;
A cleaning unit for removing toner remaining on the surface of the photosensitive drum;
A process cartridge comprising: A process cartridge according to claim 6;
An exposure device that forms an electrostatic latent image on the surface of the photosensitive drum;
A replenishing device for replenishing the developer to the developing device;
A transfer device for transferring a toner image formed on the surface of the photosensitive drum to a recording medium;
A fixing device for fixing the transferred toner image to the recording medium;
An image forming apparatus comprising: