JP5252329B2 - Developing device, image forming apparatus - Google Patents

Description

  The present invention relates to a developing device used for a copying machine, a facsimile, a printer, and the like, and an image forming apparatus using the developing device.

  Conventionally, an image forming apparatus including a developing device using a two-component developer including toner and a magnetic carrier has been widely used. As an image forming apparatus of this type, the toner density of the developer is kept within a predetermined range by supplying toner from the toner container as necessary to the developer in the developing apparatus that consumes toner with development. There is something to keep in. In such a configuration, the carrier in the developer is hardly consumed and is repeatedly used. As the image is output, the coat layer on the surface of the carrier wears out, and conversely, toner resin and additives adhere to the coat layer. To do. As a result, the ability of the carrier to charge the toner gradually decreases, and the carrier is in a deteriorated state. As the deterioration of the carrier progresses, the charge amount of the toner decreases, causing background stains and toner scattering. Therefore, in this type of image forming apparatus, a service person visits the user regularly to replace the carrier. . For this reason, maintenance costs are incurred, and the unit price for image formation is high.

Patent Document 1 discloses a developing device that discharges an increased amount of developer from the developing device while replenishing the developer in the developing device with a premix developer in which a carrier and toner are mixed to recover the toner concentration. Is described. In such a configuration, a new carrier in the premix developer is replenished to the developer in the developing device while the carrier that has become old due to the discharge of the developer is gradually discharged from the developing device. Then, the carrier replacement work can be omitted by replacing the carrier in the developer gradually with a new one by such discharge and replenishment.
Further, in the developing device of Patent Document 1, the developer discharge for discharging the developer to the outside at a predetermined height at a position where the bulk of the developer increases or decreases according to the increase or decrease of the developer amount in the entire developer transport path. Has an exit. In this developing device, when the premix developer is replenished and the amount of developer in the developing device increases, the bulk of the developer in the supply conveyance path increases. At this time, the developer reaching the height of the developer discharge port at the position where the developer discharge port is provided is discharged from the developer discharge port to the outside of the developing device.

However, when the developer transported in the developer transport path moves, or when the transport member that imparts transport force to the developer is a developer transport screw, the developer jumps by the rotating force, etc. It may be discharged from the developer outlet. When the jumped developer is discharged, even if the developer transported in the developer transport path is in an appropriate amount or less than the proper amount, the jumped developer may be discharged. is there. This is a state in which the developer is discharged even though the amount of developer in the developing device has not increased. If the developer is discharged from the developer discharge port even though the developer is in an appropriate amount or less, the amount of developer in the developing device falls below the required amount, and the development on the latent image carrier is performed. The supply of the agent might become unstable. When the supply of the developer to the latent image carrier becomes unstable, an abnormal image such as missing image occurs.
Such a problem is not limited to the developing device using the two-component developer, but the developer is replenished by the developer replenishing means, and the amount of the developer in the developing device is increased by the developer discharging means. This is a problem that may occur even in a developing device that uses a one-component developer as long as the developing device has a configuration for discharging.

  The present invention has been made in view of the above problems, and the object of the present invention is to discharge the developer even though the jumped developer is discharged and the amount of developer in the developing device has not increased. It is an object of the present invention to provide a developing device capable of stably supplying a developer to a latent image carrier by preventing this, and an image forming apparatus including the developing device.

In order to achieve the above object, the invention according to claim 1 is characterized in that the developer is carried on the surface and rotated, and the toner is supplied to the latent image on the surface of the latent image carrier at a position facing the latent image carrier. A developer carrying member for developing the developer and a developer carrying member for carrying the developer, and supplying the developer to the developer carrying member while supplying the developer to the developer carrying member. A developer transport path for transporting the developer, and developer replenishing means for replenishing the developer to the developer transport path, and the volume of the developer according to an increase or decrease in the amount of the developer in the entire developer transport path. In the developing device in which the developer discharge port for discharging the developer to the outside of the device is provided at a predetermined height at a position where the developer increases or decreases in the developer transport path, the developer flying by the transport operation of the developer transport member is comprising a flying developer discharge prevention member for closing a path toward the developer discharge port, the developer conveying The material includes a rotation shaft and a blade provided spirally on the rotation shaft, and is a developer transport screw that transports the developer in the direction of the rotation shaft by rotating, and the flying developer discharge preventing member Is a projecting member projecting downward from the casing above the developer transport path, and the shape of the lower end of the projecting member in a plane perpendicular to the transport direction of the developer transport screw is the developer transport screw. R shape der Rukoto along the top of the shape of the blade portion and is characterized in.

In the developing device having the above-described configuration of the first aspect, the flying developer discharge prevention member is provided, so that the developer flying by the transport operation of the developer transport member blocks the path toward the developer discharge port, and therefore jumps. The developer can be prevented from being discharged, and the developer can be prevented from being discharged even though the amount of the developer in the developing device has not increased .

According to the first to twelfth aspects of the present invention, it is possible to prevent the developer from being discharged even though the amount of the developer in the developing device has not increased. The amount can be secured, and there is an excellent effect that a stable developer can be supplied to the latent image carrier.

1 is a schematic configuration diagram of a copier according to an embodiment. FIG. 2 is a schematic configuration diagram of a developing device and a photoreceptor. FIG. 3 is a perspective cross-sectional view of the developing device for explaining the flow of the developer. FIG. 3 is a schematic diagram of a developer flow in a developing device. Cross-sectional explanatory drawing of a developing device. FIG. 5 is a schematic diagram of a developer flow in a developing device having a shape different from that in FIG. 4. FIG. FIG. 3 is a cross-sectional explanatory view of the developing device of Example 1. FIG. 3 is a perspective explanatory view of the vicinity of the front side end portion in a state where the stirring screw, the recovery screw, and the developing doctor are removed from the developing device of Embodiment 1. FIG. 10 is a perspective explanatory view of the vicinity of the near side in a state where a supply screw is removed from the developing device of Example 1 shown in FIG. 9. FIG. 11 is an explanatory perspective view of the vicinity of the near side in a state where the developing roller is removed from the developing device of the first embodiment illustrated in FIG. 10. FIG. 12 is a perspective explanatory view of the developing device of Example 1 shown in FIG. 11 as viewed from a direction different from FIG. 11. FIG. 6 is a cross-sectional explanatory view of a developing device according to Embodiment 2. FIG. 6 is a cross-sectional explanatory view of a developing device in which the length of a plate-like member is shorter than that in Example 2. FIG. 6 is a cross-sectional explanatory view of a developing device in which the position of a developer discharge port is lower than that in Example 2. FIG. 9 is an enlarged explanatory view of the vicinity of a downstream end of a supply conveyance path of a developing device according to Embodiment 3. Explanatory drawing of a downstream end wall surface. FIG. 3 is an explanatory side sectional view of the developing device of Reference Configuration Example 1 ; FIG. 10 is a side cross-sectional explanatory view of a developing device of Reference Configuration Example 2 . FIG. 10 is a side cross-sectional explanatory view of a developing device of Reference Configuration Example 3 . FIG. 6 is a schematic explanatory diagram of a developing device and a photoreceptor according to a modified example. Sectional explanatory drawing of the conventional image development apparatus provided with the developer discharge port.

Embodiment
Hereinafter, as an image forming apparatus to which the present invention is applied, an embodiment (hereinafter simply referred to as “ embodiment ”) of a tandem type color laser copying machine (hereinafter simply referred to as “copying machine”) in which a plurality of photoconductors are arranged in parallel. ").
FIG. 1 is a schematic configuration diagram of a copying machine according to an embodiment . The copier includes a printer unit 100, a paper feeding device 200 on which the printer unit 100 is placed, a scanner 300 fixed on the printer unit 100, and the like. An automatic document feeder 400 fixed on the scanner 300 is also provided.

  The printer unit 100 includes an image forming unit including four sets of process cartridges 18Y, 18M, 18C, and 18K for forming images of each color of yellow (Y), magenta (M), cyan (C), and black (K). 20 is provided. Y, M, C, and K attached to the numbers of the respective symbols indicate members for yellow, cyan, magenta, and black (the same applies hereinafter). In addition to the process cartridges 18Y, 18M, 18C, and 18K, an optical writing unit 21, an intermediate transfer unit 17, a secondary transfer device 22, a resist roller pair 49, a belt fixing type fixing device 25, and the like are disposed. .

  The optical writing unit 21 includes a light source (not shown), a polygon mirror, an f-θ lens, a reflection mirror, and the like, and irradiates the surface of a photoreceptor to be described later with laser light based on image data.

  The process cartridges 18Y, 18M, 18C, and 18K include a drum-shaped photosensitive member 1, a charger, a developing device 4, a drum cleaning device, a static eliminator, and the like.

Hereinafter, the yellow process cartridge 18 will be described.
The surface of the photoreceptor 1Y is uniformly charged by a charger as charging means. The surface of the photoreceptor 1 </ b> Y that has been subjected to charging processing is irradiated with laser light that has been modulated and deflected by the optical writing unit 21. Then, the potential of the irradiation part (exposure part) is attenuated. By this attenuation, an electrostatic latent image for Y is formed on the surface of the photoreceptor 1Y. The formed electrostatic latent image for Y is developed by the developing device 4Y as developing means to become a Y toner image.
The Y toner image formed on the Y photoconductor 1Y is primarily transferred to an intermediate transfer belt 110 described later. The surface of the photoreceptor 1Y after the primary transfer is cleaned of the transfer residual toner by a drum cleaning device.
In the Y process cartridge 18Y, the photoconductor 1Y cleaned by the drum cleaning device is discharged by the charge eliminator. Then, it is uniformly charged by the charger and returns to the initial state. The series of processes as described above is the same for the other process cartridges 18M, 18C, and 18K.

Next, the intermediate transfer unit will be described.
The intermediate transfer unit 17 includes an intermediate transfer belt 110, a belt cleaning device 90, and the like. Further, it also includes a tension roller 14, a driving roller 15, a secondary transfer backup roller 16, four primary transfer bias rollers 62Y, M, C, and K.
The intermediate transfer belt 110 is tensioned by a plurality of rollers including the tension roller 14. Then, it is endlessly moved clockwise in the drawing by the rotation of the driving roller 15 driven by a belt driving motor (not shown).
The four primary transfer bias rollers 62Y, 62M, 62C, and 62K are disposed so as to be in contact with the inner peripheral surface side of the intermediate transfer belt 110, respectively, and receive primary transfer bias from a power source (not shown). Further, the intermediate transfer belt 110 is pressed toward the photoreceptors 1Y, 1M, 1C, and 1K from the inner peripheral surface side to form primary transfer nips. In each primary transfer nip, a primary transfer electric field is formed between the photosensitive member and the primary transfer bias roller due to the influence of the primary transfer bias.
The above-described Y toner image formed on the Y photoconductor 1Y is primarily transferred onto the intermediate transfer belt 110 due to the influence of the primary transfer electric field and nip pressure. On the Y toner image, the M, C, K toner images formed on the M, C, K photoconductors 1M, C, K are sequentially superposed and primarily transferred. By this primary transfer of superposition, a four-color superposed toner image (hereinafter referred to as a four-color toner image) that is a multiple toner image is formed on the intermediate transfer belt 110.
The four-color toner image superimposed and transferred onto the intermediate transfer belt 110 is secondarily transferred onto a transfer sheet (not shown) as a recording medium at a secondary transfer nip described later. Transfer residual toner remaining on the surface of the intermediate transfer belt 110 after passing through the secondary transfer nip is cleaned by a belt cleaning device 90 that sandwiches the belt with the driving roller 15 on the left side in the drawing.

Next, the secondary transfer device 22 will be described.
Below the intermediate transfer unit 17 in the figure, a secondary transfer device 22 is disposed in which a paper conveying belt 24 is stretched by two stretching rollers 23. The paper transport belt 24 is moved endlessly in the counterclockwise direction in the drawing in accordance with the rotational drive of at least one of the stretching rollers 23. One of the two stretching rollers 23 arranged on the right side in the drawing sandwiches the intermediate transfer belt 110 and the paper transport belt 24 between the secondary transfer backup roller 16 of the intermediate transfer unit 17. It is out. By this sandwiching, a secondary transfer nip is formed in which the intermediate transfer belt 110 of the intermediate transfer unit 17 and the paper transport belt 24 of the secondary transfer device 22 are in contact with each other. A secondary transfer bias having a polarity opposite to that of the toner is applied to the one stretching roller 23 by a power source (not shown). By applying this secondary transfer bias, the four-color toner image on the intermediate transfer belt 110 of the intermediate transfer unit 17 is electrostatically moved from the belt side toward the one stretching roller 23 side in the secondary transfer nip. A next transfer electric field is formed. The transfer paper fed into the secondary transfer nip so as to synchronize with the four-color toner image on the intermediate transfer belt 110 by a registration roller pair 49 to be described later has four colors affected by the secondary transfer electric field and nip pressure. The toner image is secondarily transferred. Instead of the secondary transfer method in which the secondary transfer bias is applied to one of the stretching rollers 23 as described above, a charger for charging the transfer paper in a non-contact manner may be provided.

  In the paper feeding device 200 provided at the lower part of the copying machine main body, a plurality of paper feeding cassettes 44 in which a plurality of transfer sheets can be stacked and accommodated in a bundle of sheets are arranged so as to overlap in the vertical direction. Has been. Each paper feed cassette 44 presses the paper feed roller 42 against the uppermost transfer paper in the paper bundle. Then, by rotating the paper feed roller 42, the uppermost transfer paper is sent out toward the paper feed path 46.

  The paper feed path 46 that receives the transfer paper fed from the paper feed cassette 44 has a plurality of conveying roller pairs 47 and a registration roller pair 49 provided near the end in the path. Then, the transfer paper is conveyed toward the registration roller pair 49. The transfer sheet conveyed toward the registration roller pair 49 is sandwiched between the rollers of the registration roller pair 49. On the other hand, in the intermediate transfer unit 17, the four-color toner image formed on the intermediate transfer belt 110 enters the secondary transfer nip as the belt moves endlessly. The registration roller pair 49 sends out the transfer paper sandwiched between the rollers at a timing at which the transfer paper can be brought into close contact with the four-color toner image at the secondary transfer nip. Thereby, in the secondary transfer nip, the four-color toner image on the intermediate transfer belt 110 is in close contact with the transfer paper. Then, it is secondarily transferred onto the transfer paper and becomes a full color image on the white transfer paper. The transfer paper on which the full-color image is formed in this manner exits the secondary transfer nip as the paper transport belt 24 moves endlessly, and then is sent from the paper transport belt 24 to the fixing device 25.

  The fixing device 25 includes a belt unit that moves the fixing belt 26 endlessly while being stretched by two rollers, and a pressure roller 27 that is pressed toward one roller of the belt unit. The fixing belt 26 and the pressure roller 27 are in contact with each other to form a fixing nip, and the transfer paper received from the paper transport belt 24 is sandwiched therebetween. Of the two rollers in the belt unit, the roller that is pressed from the pressure roller 27 has a heat source (not shown) inside, and pressurizes the fixing belt 26 by the generated heat. The pressed fixing belt 26 heats the transfer paper sandwiched in the fixing nip. The full color image is fixed on the transfer paper by the influence of the heating and the nip pressure.

  The transfer paper subjected to the fixing process in the fixing device 25 is stacked on the stack portion 57 provided outside the left side plate in the drawing of the printer housing, or forms a toner image on the other surface. To the secondary transfer nip described above.

  When a document (not shown) is copied, for example, a bundle of sheet documents is set on the document table 30 of the automatic document feeder 400. However, when the original is a single-sided original that is closed in a main form, it is set on the contact glass 32. Prior to this setting, the automatic document feeder 400 is opened with respect to the copying machine main body, and the contact glass 32 of the scanner 300 is exposed. Thereafter, the single-bound original is pressed by the closed automatic document feeder 400.

  When a copy start switch (not shown) is pressed after the document is set in this way, the document reading operation by the scanner 300 starts. However, when a sheet document is set on the automatic document feeder 400, the automatic document feeder 400 automatically moves the sheet document to the contact glass 32 prior to the document reading operation. In the document reading operation, first, the first traveling body 33 and the second traveling body 34 start traveling together, and light is emitted from a light source provided in the first traveling body 33. Then, the reflected light from the document surface is reflected by a mirror provided in the second traveling body 34, passes through the imaging lens 35, and then enters the reading sensor 36. The reading sensor 36 constructs image information based on the incident light.

  In parallel with such a document reading operation, each device in each of the process cartridges 18Y, 18M, 18C, 18K, the intermediate transfer unit 17, the secondary transfer device 22, and the fixing device 25 starts driving. Based on the image information constructed by the reading sensor 36, the optical writing unit 21 is driven and controlled, and Y, M, C, and K toner images are formed on the photoreceptors 40Y, 40M, 40C, and 40K. Is done. These toner images become four-color toner images superimposed and transferred on the intermediate transfer belt 110.

  Further, almost simultaneously with the start of the document reading operation, the paper feeding operation is started in the paper feeding device 200. In this paper feeding operation, one of the paper feeding rollers 42 is selectively rotated, and the transfer paper is sent out from one of the paper feeding cassettes 44 accommodated in the paper bank 43 in multiple stages. The fed transfer sheets are separated one by one by the separation roller 45 and enter the reverse feeding path 46, and then conveyed toward the secondary transfer nip by the conveyance roller pair 47. In some cases, paper feeding from the manual feed tray 51 is performed instead of such paper feeding from the paper feeding cassette 44. In this case, after the manual feed roller 50 is selectively rotated to feed the transfer paper on the manual feed tray 51, the separation roller 52 separates the transfer paper one by one and feeds it to the manual feed path 53 of the printer unit 100. Make paper.

  In the case of forming another color image composed of two or more colors of toner, the copying machine stretches the intermediate transfer belt 110 so that the upper stretched surface thereof is substantially horizontal, Photoconductors 1Y, 1M, 1C, and 1K are brought into contact with each other. On the other hand, when forming a monochrome image consisting of only K toner, the intermediate transfer belt 110 is tilted to the lower left in the drawing by a mechanism (not shown) and the upper stretched surface is set to Y, M, C. The photoconductors 1Y, 1M, and 1C are separated. Of the four photoconductors 1Y, 1M, 1C, and 1K, only the K photoconductor 1K is rotated counterclockwise in the drawing to form only the K toner image. At this time, for Y, M, and C, not only the photosensitive member 1 but also the developing device is stopped to prevent unnecessary consumption of the photosensitive member and the developer.

  The copying machine includes a control unit (not shown) configured by a CPU or the like that controls the following devices in the copying machine, and an operation display unit (not shown) configured by a liquid crystal display, various key buttons, and the like. The operator sends a command to the control unit by a key input operation on the operation display unit, so that one of the three modes is selected from the three-sided print mode, which is a mode for forming an image only on one side of the transfer paper. You can choose one. The three single-sided printing modes include a direct discharge mode, a reverse discharge mode, and a reverse decal discharge mode.

FIG. 2 is an enlarged configuration diagram illustrating the developing device 4 and the photosensitive member 1 included in one of the four process cartridges 18Y, 18M, 18C, and 18K. Since the four process cartridges 18Y, 18M, 18C, and 18K have substantially the same configuration except that the colors of the toners to be handled are different, they are referred to as “Y”, “M”, “C”, and “K” in FIG. Subscripts are omitted.
As shown in FIG. 2, the surface of the photosensitive member 1 is charged by a charging device (not shown) while rotating in the direction of arrow G in the drawing. The charged surface of the photoreceptor 1 is supplied with toner from the developing device 4 to a latent image on which an electrostatic latent image is formed by laser light emitted from an exposure device (not shown), thereby forming a toner image.

The developing device 4 has a developing roller 5 as a developer carrying member for supplying toner to the latent image on the surface of the photoreceptor 1 while moving the surface in the direction of arrow I in the drawing. Further, a supply screw 8 is provided as a supply conveyance member that conveys the developer in the depth direction of FIG. 2 while supplying the developer to the developing roller 5. The supply screw 8 is a developer conveying screw that includes a rotating shaft and a blade portion provided on the rotating shaft and conveys the developer in the axial direction by rotating.
A developing doctor 12 as a developer regulating member for regulating the developer supplied to the developing roller 5 to a thickness suitable for development is provided on the downstream side of the surface moving direction from the portion facing the supply screw 8 of the developing roller 5. ing.
The developed developer that has passed through the developing section is collected downstream from the developing section, which is the facing portion of the developing roller 5 with respect to the photoconductor 1, and the collected developer is collected in the same direction as the supply screw 8. A recovery screw 6 is provided as a recovery transport member for transporting to the front. A supply conveyance path 9 including a supply screw 8 is provided in the lateral direction of the developing roller 5, and a recovery conveyance path 7 serving as a recovery conveyance path including the recovery screw 6 is provided below the development roller 5.

The developing device 4 is provided with a stirring conveyance path 10 in parallel with the collection conveyance path 7 below the supply conveyance path 9. The agitating and conveying path 10 includes an agitating screw 11 serving as an agitating and conveying member that conveys the developer to the near side in the figure, which is in the opposite direction to the supply screw 8 while agitating the developer.
The supply conveyance path 9 and the stirring conveyance path 10 are partitioned by a first partition wall 133 as a partition member. In the first partition wall 133, the supply conveyance path 9 and the agitation conveyance path 10 are partitioned at both ends on the front side and the back side in the drawing, and the supply conveyance path 9 and the agitation conveyance path 10 communicate with each other. doing.
The supply conveyance path 9 and the recovery conveyance path 7 are both partitioned by the first partition wall 133, but an opening is provided at a location where the supply conveyance path 9 and the recovery conveyance path 7 of the first partition wall 133 are partitioned. Absent.
Further, the two conveyance paths of the stirring conveyance path 10 and the collection conveyance path 7 are partitioned by a second partition wall 134 as a partition member. The second partition wall 134 has an opening on the front side in the figure, and the agitation transport path 10 and the collection transport path 7 communicate with each other.
The supply screw 8, the recovery screw 6 and the stirring screw 11, which are developer conveying members, are made of resin or metal screws, and each screw has a diameter of φ22 [mm] and the screw pitch is 50 [mm]. The winding, the recovery screw 6 and the stirring screw 11 are one roll of 25 [mm], and the number of rotations is all set to about 600 [rpm].

The developer thinned by the developing doctor 12 made of stainless steel on the developing roller 5 is transported to a developing area which is a portion facing the photosensitive member 1 for development. The surface of the developing roller 5 is V-groove or sandblasted and is made of an Al or SUS base tube of φ25 [mm], and the gap between the developing doctor 12 and the photoreceptor 1 is about 0.3 [mm].
The developer after the development is collected in the collection conveyance path 7, conveyed to the front side of the cross section in FIG. 2, and to the agitation conveyance path 10 through the opening of the first partition wall 133 provided in the non-image area portion. Developer is transferred. The toner is supplied to the stirring and conveying path 10 from the toner supply port provided on the upper side of the stirring and conveying path 10 near the opening of the first partition wall 133 on the upstream side in the developer conveying direction in the stirring and conveying path 10.

Next, the circulation of the developer in the three developer conveyance paths will be described.
FIG. 3 is a perspective sectional view of the developing device 4 for explaining the flow of the developer in the developer transport path. Each arrow in the figure indicates the moving direction of the developer.
4 is a schematic diagram of the flow of the developer in the developing device 4. Like FIG. 3, each arrow in the drawing indicates the moving direction of the developer.

In the supply conveyance path 9 that has been supplied with the developer from the agitation conveyance path 10, the developer is conveyed downstream in the conveyance direction of the supply screw 8 while supplying the developer to the developing roller 5. Then, the excess developer that is supplied to the developing roller 5 and is not used for development and is transported to the downstream end in the transport direction of the supply transport path 9 is supplied to the stirring transport path 10 from the surplus opening 92 of the first partition wall 133 ( Arrow E) in FIG.
The collected developer that is sent from the developing roller 5 to the collection conveyance path 7 and conveyed to the downstream end in the conveyance direction of the collection conveyance path 7 by the collection screw 6 is supplied to the stirring conveyance path 10 from the collection opening 93 of the second partition wall 134. (Arrow F in FIG. 4).
The agitating and conveying path 10 agitates the supplied surplus developer and the recovered developer, conveys the agitating screw 11 to the downstream side in the conveying direction, and conveys it to the upstream side in the conveying direction of the supplying screw 8. It is supplied to the supply conveyance path 9 from the supply opening 91 of 133 (arrow D in FIG. 4).
In the agitating and conveying path 10, the agitating screw 11 agitates and conveys the collected developer, the surplus developer, and the toner replenished as necessary in the transfer unit in the direction opposite to the developer in the collecting and conveying path 7 and the supply conveying path 9. . Then, the agitated developer is transferred to the upstream side in the conveyance direction of the supply conveyance path 9 communicating with the downstream side in the conveyance direction. A toner concentration sensor (not shown) is provided below the agitation transport path 10, and a toner supply control device (not shown) is operated by the sensor output to supply toner from a toner storage portion (not shown).

  In the developing device 4 shown in FIG. 4, a supply conveyance path 9 and a collection conveyance path 7 are provided, and developer supply and collection are performed in different developer conveyance paths, so that the developed developer is supplied to the supply conveyance path 9. There is no contamination. Accordingly, it is possible to prevent the toner density of the developer supplied to the developing roller 5 from decreasing toward the downstream side of the supply conveyance path 9 in the conveyance direction. Further, since the recovery conveyance path 7 and the agitation conveyance path 10 are provided and the developer recovery and agitation are performed in different developer conveyance paths, the developed developer does not fall during the agitation. Therefore, since the sufficiently agitated developer is supplied to the supply conveyance path 9, it is possible to prevent the developer supplied to the supply conveyance path 9 from being insufficiently agitated. In this way, the toner density of the developer in the supply conveyance path 9 can be prevented from decreasing, and the developer in the supply conveyance path 9 can be prevented from being insufficiently stirred. Can be constant.

As shown in FIG. 4, the developer moves from the lower part to the upper part of the developing device 4 only by the arrow D. The movement of the developer indicated by an arrow D is to push the developer by rotating the stirring screw 11 so that the developer is raised and supplied to the supply conveyance path 9.
Such movement of the developer gives stress to the developer and contributes to a decrease in the life of the developer.
When the developer is lifted from the bottom to the top, stress is applied to the developer, and the carrier film in the developer is scraped off and the toner is spent on the spot. Accordingly, the stability of the image quality is maintained. It will disappear.
Therefore, the life of the developer can be extended by reducing the stress of the developer in the movement of the developer indicated by the arrow D. By prolonging the life of the developer, it is possible to provide a developing device that prevents deterioration of the developer and is always stable in image quality without image density unevenness.

In the developing device 4 of the embodiment , as shown in FIG. 2, the supply conveyance path 9 is disposed obliquely above the stirring conveyance path 10. By disposing it obliquely above, it is possible to reduce the developer stress in the movement of the developer indicated by the arrow D, compared to the case where the supply conveyance path 9 is provided vertically above the stirring conveyance path 10 and the developer is lifted. .
Further, in the developing device 4, the supply conveyance path 9 and the agitation conveyance path 10 are arranged obliquely so that the upper wall surface of the agitation conveyance path 10 is higher than the lower wall surface of the supply conveyance path 9 as shown in FIG. 2. It arranges so that it may become a position.
Lifting the supply conveyance path 9 vertically upward with respect to the stirring conveyance path 10 causes the developer to be stressed because the developer is lifted by the pressure of the stirring screw 11 against gravity. On the other hand, the developer present at the highest point of the agitating and conveying path 10 is placed at the bottom of the supplying and conveying path 9 by arranging the upper wall surface of the agitating and conveying path 10 to be higher than the lower wall surface of the supplying and conveying path 9. Since the point can flow without being against gravity, the stress applied to the developer can be reduced.
Note that a fin member may be provided on the shaft of the stirring screw 11 in a portion where the stirring transport path 10 and the supply transport path 9 communicate with each other on the downstream side of the developer transport path of the stirring transport path 10. This fin member is a plate-like member composed of a side parallel to the axial direction of the stirring screw 11 and a side perpendicular to the axial direction of the stirring screw. By scooping up the developer with this fin member, it is possible to more efficiently deliver the developer from the stirring conveyance path 10 to the supply conveyance path 9.

Further, in the developing device 4, the distance between the center A between the developing roller 5 and the supply conveyance path 9 is shorter than the distance B between the center between the development roller 5 and the agitation conveyance path 10. A conveyance path 10 is arranged. Thus, the developer can be supplied without difficulty from the supply conveyance path 9 to the developing roller 5, and the apparatus can be reduced in size.
Further, the stirring screw 11 is rotated counterclockwise as viewed from the front side in FIG. 2 (the direction of arrow C in the figure), and the developer is supplied by lifting the developer along the shape of the stirring screw 11. It is transferred to the conveyance path 9. As a result, the developer can be lifted efficiently, and the stress on the developer can be further reduced.

FIG. 5 is a cross-sectional explanatory view of the cross section at the rotation center of the supply screw 8 of the developing device 4 as viewed from the direction of arrow J in FIG. In the figure, H denotes a developing region in which the developing roller 5 that is a developer carrying member supplies toner to the photosensitive member 1 that is a latent image carrying member. The width in the axial direction of the rotation axis of the developing roller 5 in the developing area H is the developing area width α.
As shown in FIG. 5, the developing device 4 has a supply opening 91 that is a part for lifting the developer from the agitation conveyance path 10 to the supply conveyance path 9, and a surplus that drops the developer from the supply conveyance path 9 to the agitation conveyance path 10. Both of the openings 92 are provided in the development region width α.

FIG. 6 is a schematic diagram of the developer flow in the developing device 4 having a configuration different from that in FIG. 4.
The developing device 4 shown in FIG. 6 is provided with a supply opening 91 and a surplus opening 92 outside the developing region width α. Since the supply opening 91 is provided outside the developing region width α, the upstream side in the transport direction of the supply transport path 9 is longer than the developing roller 5 by the upstream region β of the supply transport path. Further, since the surplus opening 92 is provided outside the developing region width α, the downstream side in the transport direction of the supply transport path 9 is longer than the developing roller 5 by the region γ on the downstream side of the supply transport path.

On the other hand, in the developing device 4 having the configuration shown in FIG. 4, since the supply opening 91 is provided within the developing region width α, the upstream side in the transport direction of the supply transport path 9 is on the supply transport path than the developing device 4 in FIG. The flow side region β can be shortened. Further, since the surplus opening 92 is provided in the developing area width α, the downstream side in the transport direction of the supply transport path 9 can be made shorter by the area γ on the downstream side of the supply transport path than the developing device 4 in FIG.
4 is provided with the supply opening 91 and the surplus opening 92 within the developing region width α, the upper portion of the developing device 4 is higher than that of the developing device 4 shown in FIG. Space saving can be achieved.

Next, the position at which toner is supplied to the developer conveyance path including the supply conveyance path 9, the agitation conveyance path 10 and the collection conveyance path 7 of the developing device 4 will be described. FIG. 7 is an external perspective view of the developing device 4.
As shown in FIG. 7, a toner replenishing port 95 for replenishing toner is provided above the upstream end of the agitating and conveying path 10 including the agitating screw 11 in the conveying direction. Since the toner replenishing port 95 is provided outside the end portion in the width direction of the developing roller 5, it is outside the developing region width α.
The portion where the toner replenishing port 95 is provided is on an extension line in the conveyance direction of the supply conveyance path 9 and corresponds to a vacant space in the region γ on the downstream side of the supply conveyance path in FIG. Providing the toner replenishment port 95 in an empty space by providing the surplus opening 92 within the developing region width α makes it possible to reduce the size of the developing device 4.
Further, the toner replenishing port 95 is not limited to the position above the upstream end portion in the transport direction of the stirring transport path 10 and may be provided above the downstream end portion of the collection transport path 7.
Further, a toner replenishing port 95 may be provided directly above the collection opening 93 where the developer is transferred from the collection conveyance path 7 to the stirring conveyance path 10. Since the space directly above the collection opening 93 is also an empty space provided by providing the surplus opening 92 within the developing region width α, the toner replenishing port 95 is provided at this position to reduce the size of the developing device 4. Can be planned. Furthermore, since the developer is likely to be mixed in the collection opening 93 serving as a delivery unit, the developer can be more efficiently stirred by replenishing at this position.

As in the developing device 4 described with reference to FIG. 4, a supply opening 91 that transfers the developer from the downstream end in the transport direction of the stirring transport path 10 to the upstream end in the transport direction of the supply transport path 9, and the supply transport path 9 Since the surplus opening 92 for transferring the developer from the downstream end to the upstream end in the transport direction of the stirring transport path 10 is provided in the development region width α, the upper portion of the development device 4 is higher than the conventional development device 4. Space can be saved, and the space of the entire developing device 4 can be saved.
Also, by providing the toner replenishment port 95 in the empty space by providing the surplus opening 92 within the development region width α, the development device 4 can be downsized.
Further, the developer can be more efficiently stirred by replenishing the toner from above the recovery opening 93 that is a delivery portion of the developer from the recovery transport path 7 to the stirring transport path 10.
Further, by providing the developing device 4 as the developing means of the printer unit 100 of the copying machine as the image forming apparatus, it is possible to save the space of the entire apparatus.

Next, replacement of the developer in the developing device 4 will be described.
A toner replenishment control device (not shown) that is a developer replenishing unit replenishes toner in a toner storage unit (not shown) to the developing device 4 from the toner replenishing port 95. In the developing device 4 of the embodiment, a developer including toner and a carrier is supplied from a toner supply port 95 of the developing device 4. Hereinafter, the developer in which the toner supplied to the developing device 4 and the carrier are mixed is referred to as premix toner.
Further, in the supply conveyance path 9, when the developer in the supply conveyance path 9 exceeds a predetermined volume, a developer discharge port 94 for discharging a part thereof to the outside of the developing device 4 and a developer discharge port 94. And a discharge conveyance path 2 provided with a discharge conveyance screw 2a for conveying the developer discharged from the developing device 4 to the outside. The discharge conveyance path 2 is disposed on the downstream side in the conveyance direction of the supply conveyance path 9 so as to be adjacent to the supply conveyance path 9 with the partition wall 135 interposed therebetween, and the developer discharge port 94 is connected to the supply conveyance path 9 and the discharge conveyance path 2. Is an opening provided in the partition wall 135 so as to communicate with each other.

Next, the conventional developing device 4 provided with the developer discharge port 94 will be described.
FIG. 22 is a cross-sectional explanatory view of the developing device 4 in the vicinity of the downstream end in the transport direction of the supply transport path 9 as viewed from the same direction as FIG. 2 for the conventional developing device 4 provided with the developer discharge port 94.
The vicinity of the downstream end of the supply conveyance path 9 in the conveyance direction is, for example, the same position in the conveyance direction of the developer conveyance section 9 and the supply conveyance path 9 where the developer is transferred from the supply conveyance path 9 to the stirring conveyance path 10. It is a place.

Further, the rotation direction of the supply screw 8 in the supply conveyance path 9 is clockwise (direction of arrow M) as shown in FIG. 8, and the developer is supplied to the developing roller 5 from below. It is rotating. Here, when the developer is supplied to the developing roller 5 so that the rotation direction of the supply screw 8 is counterclockwise and the developer is sprinkled from above, the developer is supplied to the developing roller 5 while being scattered. On the other hand, when the rotation direction of the supply screw 8 is clockwise as shown in FIG. 8, the developer is supplied to the developing roller 5 so as to lift the developer from below the supply conveyance path 9 in which the developer is accumulated. It becomes like this. Since the developer supply performance is more stable when the developer is supplied from the lower side than when the developer is supplied while being scattered, the rotation direction of the supply screw 8 is set clockwise in FIG. doing.
In particular, in the case where the developer supplied to the developing roller 5 is not returned to the supply conveyance path 9 but is collected to the collection conveyance path 7 as in the developing device 4 of this embodiment, the amount of developer goes downstream of the supply conveyance path 9. It decreases according to. For this reason, it is more excellent in terms of developer supply that the developer is drawn up from below and supplied to the developing roller 5.

Here, the developer in the supply conveyance path 9 jumps by the momentum of movement in the supply conveyance path 9 by being conveyed and the rotating force of the supply screw 8 that is a developer conveyance screw. As shown in FIG. 22, when the developer discharge port 94 is simply provided at a predetermined height of the supply conveyance path 9 that is a developer conveyance path, as shown by an arrow T in FIG. 22. On the path, the jumped developer may fly and pass through the developer discharge port 94 and be discharged. When the developer jumps and is discharged, even if the developer transported through the position where the developer discharge port 94 in the supply transport path 9 is provided is in an appropriate amount or less than the appropriate amount, The jumped developer may be discharged. In such a state where the developer jumped off is discharged, the developer may be discharged from the developer discharge port even though the amount of the developer in the developing device 4 is not more than an appropriate amount. The amount of developer in the developing device 4 is less than the required amount, and the supply of developer to the photoreceptor 1 may become unstable. When the developer supply to the photosensitive member 1 becomes unstable, an abnormal image such as image omission occurs.
In FIG. 22, the path of the jumped developer toward the developer discharge port 94 is indicated by an arrow T. The arrow T schematically shows the path of the jumped developer toward the developer discharge port 94, and the path of the jumped developer toward the developer discharge port 94 is limited to that indicated by the arrow T. is not.

[Example 1]
Next, an embodiment of the first one having the features of the developing device 4 of the embodiment (hereinafter, referred to as "Example 1") will be described.
FIG. 8 is an explanatory cross-sectional view of the developing device 4 according to the first embodiment. FIG. 9 is a perspective explanatory view of the vicinity of the front side end portion in a state where the stirring screw 11, the recovery screw 6, and the developing doctor 12 are removed from the developing device 4 of the first embodiment. FIG. 10 is a perspective explanatory view of the developing device 4 of the first embodiment when the front side of the developing device 4 in the state where the supply screw 8 is further removed from the state of FIG. Further, FIG. 11 is a perspective explanatory view of the developing device 4 of Embodiment 1 in a state where the developing roller 5 is further removed from the state of FIG. 12 is an explanatory perspective view of the developing device 4 of the first embodiment when the developing device 4 in the same state as that of FIG. 11 is viewed from the substantially same direction as FIG.

  As illustrated in FIG. 8, the developing device 4 according to the first exemplary embodiment is configured such that the developer flying as the supply screw 8 that is a developer conveying member rotates to convey the developer travels toward the developer discharge port 94. As a flying developer discharge preventing member for closing (arrow T in FIG. 22), a block member 3 is provided. The developer in the developing device 4 is provided with the block member 3, and the developer flying by the feeding operation of the supply screw 8 blocks the path toward the developer discharge port 94, thereby preventing the jumped developer from being discharged. It is possible to prevent the developer from being discharged even though the amount is not increased. Therefore, the necessary amount of developer in the developing device 4 can be secured, and the developer can be stably supplied to the photoreceptor 1. As a result, the electrostatic latent image on the photoreceptor 1 can be favorably converted into a toner image, an abnormal image such as image omission can be prevented, and good image formation can be performed.

Further, in the developing device 4 of Example 1, a straight line (L1 in FIG. 8) connecting the lowest point (Q in FIG. 8) of the developer discharge port 94 and the upper apex (P in FIG. 8) of the supply screw 8. The block member 3 is provided so as to close the block. The block member 3 is provided at a portion facing the developer discharge port 94. The developer discharged from the developer discharge port 94 is divided into a partition wall 135 below the developer discharge port 94, the block member 3, a side wall 3 f on the near side of the block member 3, and a side wall on the back side of the block member 3. The developer discharge port 94 is reached through the space surrounded by 3b. By providing the block member 3 so as to block the straight line L1, the developer flying in the tangential direction of the circumference drawn by the wing from the vicinity of the upper vertex P of the supply screw 8 is prevented from passing through the developer discharge port 94. be able to. Further, as shown in FIG. 8, since the block member 3 is a member arranged so as to block the straight line L1 from the casing of the developing device 4 above the supply conveyance path 9, the development that flies above the straight line L1. The path (arrow T in FIG. 22) toward the developer discharge port 94 can be blocked. Thereby, it is possible to more reliably prevent the flying developer from reaching the developer discharge port 94.
Further, the block member 3 is an R-shaped resin member having a bottom surface along the shape of the supply screw 8 at the upper portion of the supply conveyance path 9. Due to the R shape along the shape of the supply screw 8, the bottom surface of the block member 3 can be brought close to the supply screw 8 as a whole so as to cover the entire supply screw 8. For this reason, it is possible to cover the upper portion of the supply screw 8 that causes the developer to jump up, and to prevent the developer jumped up by the supply screw 8 from flying to the developer discharge port 94.

Further, as shown in FIG. 12, the block member 3 protrudes around the developer discharge port 94 of the supply conveyance path 9, so that the supply screw 8 on the upstream side in the conveyance direction of the supply screw 8 with respect to the block member 3. The supply conveyance path where the block member 3 is provided is narrower than the conveyance path 9. Therefore, the developer amount with respect to the capacity of the supply conveyance path 9 is larger at the position where the block member 3 is provided than at the upstream side in the conveyance direction with respect to the position where the block member 3 is provided. Therefore, the developer rises between the side wall of the block member 3 and the partition wall 135 in the vicinity of the downstream end in the conveyance direction of the supply conveyance path 9 where no conveyance force is applied to the developer. As a result, the supply screw 8 is buried in the developer, and the splashing of the developer due to the rotation of the supply screw 8 is suppressed, and the upper part of the wing portion of the supply screw 8 protrudes from the developer surface. A change in the surface of the material caused by the splashing of the supply screw that occurs sometimes is mitigated in the vicinity of the developer discharge port 94. For this reason, it is possible to expect discharge with high sensitivity to increase / decrease of the developer in the developing device 4.
By providing such a block member 3, when the bulk increases due to the supply of the developer, the developer corresponding to the increased amount overflows from the developer discharge port 94.

In the developing device 4, when the premix toner is supplied into the developing device 4 by a toner supply control device (not shown) and the amount of developer in the developing device 4 increases, the supply conveying path 9 near the downstream end in the conveying direction. The bulk of the developer increases.
Hereinafter, it will be described that as the amount of developer in the developing device 4 increases, the bulk of the developer near the downstream end in the transport direction of the supply transport path 9 increases.

In the developing device 4, the developer developer by the change in the developer conveyance amount by the stirring screw 11 when the premix toner is replenished or the change in the developer delivery amount from the stirring conveyance path 10 to the supply conveyance path 9. Trends are different.
For example, when the amount of developer transported by the stirring screw 11 does not change so much while the premix toner is supplied, the amount of developer supplied upstream in the transport direction of the supply transport path 9 does not change much. Even when the configuration in which the developer is delivered from the agitation conveyance path 10 to the supply conveyance path 9 is close to the upper limit of the amount that can be delivered when the developer is not replenished, the supply conveyance path 9 in the conveyance direction upstream side The amount of developer supplied to the toner does not change much.

In the developing device 4 having such a configuration, even when the premix toner is replenished, the amount of developer conveyed through the supply conveyance path 9 does not change, and the amount of developer supplied from the supply conveyance path 9 to the developing roller 5 is changed. Therefore, the amount of the developer reaching the vicinity of the downstream end in the transport direction of the supply transport path 9 per time by the supply screw 8 hardly changes.
On the other hand, when the conveyance amount of the agitation conveyance path 10 does not change much, when the premix toner is replenished from the toner replenishing port 95, the increased developer stays in the vicinity of the upstream end of the agitation conveyance path 10 in the conveyance direction. Further, when the delivery amount from the agitation conveyance path 10 to the supply conveyance path 9 does not change, the increased amount of developer stays in the agitation conveyance path 10 and also stays in the vicinity of the upstream end in the conveyance direction.
When the developer stays in the vicinity of the upstream end in the transport direction, the surplus opening 92 that delivers the developer from the supply transport path 9 to the stirring transport path 10 is closed by the developer on the stirring transport path 10 side. When the excess opening 92 is blocked by the developer, the developer cannot be moved from the supply conveyance path 9 to the stirring conveyance path 10, but the developer is continuously conveyed by the supply screw 8, so that the conveyance of the supply conveyance path 9 is performed. The developer stays in the vicinity of the downstream end in the direction, and its bulk increases. When the volume of the developer near the downstream end in the conveyance direction of the supply conveyance path 9 rises to the height of the developer discharge port 94, the developer P is discharged to the discharge conveyance path 2 and developed through the discharge conveyance path 2. It is discharged outside the device 4.
In this configuration, when the developer in the agitation transport path 10 is full, the excess developer that has been transported to the most downstream side in the transport direction of the supply transport path 9 without being used for development is supplied and transported to the agitation transport path 10. By setting the surplus opening 92 to overflow with the developer, the movement of the developer from the supply conveyance path 9 to the agitation conveyance path 10 can be restricted, and as a result, the developer that has lost its destination is the developer discharge port. Then, the developer can be discharged.
As described above, even if the developer amount in the developing device 4 increases, even if the developer amount supplied per hour from the agitation transport path 10 to the supply transport path 9 does not change much, the supply transport path 9 By disposing the developer discharge port 94 at the downstream end in the transport direction, the developer in the developing device 4 can be replaced.

In addition, when the premix toner is replenished, the amount of the developer supplied to the upstream side of the supply conveyance path 9 in the conveyance direction increases, but the amount of developer from the supply conveyance path 9 to the stirring conveyance path 10 increases. Some configurations have an upper limit on the delivery amount.
In the developing device 4 having such a configuration, when the premix toner is replenished, the conveyance amount of the agitation conveyance path 10 increases as the developer increases, and development from the agitation conveyance path 10 to the supply conveyance path 9 occurs. The amount of drug delivery will also increase. As a result, the amount of developer supplied to the upstream end of the supply conveyance path 9 in the conveyance direction increases, and the amount of developer conveyed in the supply conveyance path 9 also increases. However, since the amount of developer supplied from the supply conveyance path 9 to the developing roller 5 does not change, the amount of developer that reaches the vicinity of the downstream end in the conveyance direction of the supply conveyance path 9 increases per time. When the amount of developer that reaches the vicinity of the downstream end in the conveyance direction of the supply conveyance path 9 per time exceeds the upper limit of the delivery amount of developer from the supply conveyance path 9 to the stirring conveyance path 10 per hour, the supply conveyance The developer stays in the vicinity of the downstream end of the path 9 in the transport direction, and its bulk increases. When the volume of the developer near the downstream end in the conveyance direction of the supply conveyance path 9 rises to the height of the developer discharge port 94, the developer P is discharged to the discharge conveyance path 2 and developed through the discharge conveyance path 2. It is discharged outside the device 4.
As described above, even when the developer amount in the developing device 4 increases, the amount of developer supplied from the agitation transport path 10 to the supply transport path 9 per unit time increases, even in the transport direction of the supply transport path 9. By disposing the developer discharge port 94 at the downstream end, the developer in the developing device 4 can be replaced.

As described above, the developer discharge port 94 is provided in the vicinity of the downstream end of the supply conveyance path 9 where the volume of the developer fluctuates in accordance with the amount of the developer in the developing device 4. The developer inside can be replaced.
Further, when the premix toner is replenished, that is, when the amount of developer in the entire developer transport path increases, the amount of developer supplied to the upstream side in the transport direction of the supply transport path 9 increases accordingly. For example, the developer discharge port 94 can be provided at any position in the developer transport direction in the supply transport path 9. This is because the configuration in which the amount of developer supplied to the upstream side of the supply conveyance path 9 in the conveyance direction increases the bulk of the developer at any position in the developer conveyance direction in the supply conveyance path 9. is there.
However, when the developer discharge port 94 is provided in the middle of the developer supply region width α of the supply conveyance path 9 and the height of the developer conveyed in the supply conveyance path 9 varies, it is partially When the developer at a high volume is discharged at the developer discharge port 94, the developer may be insufficient on the downstream side of the position where the developer discharge port 94 is provided. If the developer is insufficient within the developer supply / conveyance area width α of the supply / conveyance path 9, the supply of the developer to the developing roller 5 is insufficient, and the supply of the developer from the developing roller 5 to the photoreceptor 1 is insufficient. May cause abnormal images such as missing images. On the other hand, by providing the developer discharge port 94 in the vicinity of the downstream end of the supply conveyance path 9, the downstream end of the developer discharge port 94 is outside the supply conveyance region width α. The shortage can be prevented.

By providing the block member 3 as shown in FIG. 8, it is possible to prevent the developer from jumping to the developer discharge port 94. However, when the amount of the developer in the developing device 4 increases and the volume of the developer increases to the position where the developer discharge port 94 is provided, there is a possibility that the developer may be suppressed on the lower surface of the block member 3. . If the developer is restrained by the lower surface of the block member 3 in a state where the developer is increasing in volume, the stress of the developer increases and the developer may be easily deteriorated.
On the other hand, by using an elastic material such as sponge as the material of the block member 3, when the volume of the developer increases and reaches the lower surface of the block member 3, the block of the developer is further increased. The member 3 is deformed. Due to this deformation, it is possible to prevent the stress of the developer from increasing due to the lower surface of the block member 3 suppressing the developer.

[Example 2]
Next, an embodiment of the second having the features of the developing device 4 of the embodiment (hereinafter, referred to as "Example 2") will be described.
FIG. 13 is a cross-sectional explanatory view of the developing device 4 according to the second embodiment.
In the second embodiment, the shape of the flying developer discharge preventing member is different from that of the first embodiment, and the other configurations are common, so only the differences will be described.
As shown in FIG. 13, the developing device 4 of Example 2 has a plurality of plate-like members 3 a arranged as a flying developer discharge preventing member at intervals. Even in such a configuration including the plate-like member 3 a, the developer flying by the feeding operation of the supply screw 8 may block the path toward the developer discharge port 94 as in the block member 3 of the first embodiment. it can. Therefore, it is possible to prevent the jumped developer from being discharged, and to prevent the developer from being discharged even though the amount of developer in the developing device 4 has not increased. Therefore, the necessary amount of developer in the developing device 4 can be secured, and the developer can be stably supplied to the photoreceptor 1. As a result, the electrostatic latent image on the photoreceptor 1 can be favorably converted into a toner image, an abnormal image such as image omission can be prevented, and good image formation can be performed.
Further, when the amount of the developer in the developing device 4 is increased and the volume of the developer is increased, the increased amount of the developer enters the gap between the plate-like members 3a. As a result, it is possible to reliably eliminate the effect of the developer splash without applying pressure to the developer, and to guide only the increased amount of developer to the developer discharge port 94. The plate-like member 3a can be formed of a highly rigid resin material that does not easily deform, but may be formed of an elastic material. For example, a mylar made of a PET material having a thickness of about 0.1 to 0.2 [mm] may be provided as the plate-like member 3a. In such a configuration, the mylar acts as a wall when the developer is flipped up, so that the developer does not enter the developer discharge port 94 directly. If the volume of the developer increases, the mylar deforms and develops. The developer is led to the developer discharge port 94.

The flying developer discharge preventing member of Example 1 and Example 2 is disposed so as to block the straight line L1 from the upper casing of the developing device 4 above the supply conveyance path 9, but the flying developer discharge preventing member is disposed. However, it is not limited to this.
For example, as shown in FIG. 14, a configuration may be employed in which a plate-like member 3 a having a length that is disposed inside the upper casing and does not reach the straight line L <b> 1 is provided. As long as the flying developer is a member that blocks a space that becomes a path toward the developer discharge port 94, the development jumped as compared with the developing device 4 that does not include the conventional flying developer discharge prevention member as shown in FIG. It is possible to prevent the agent from flying and reaching the developer discharge port 94. Thereby, it is possible to prevent the developer in the developing device 4 from being insufficient, and to stably supply the developer to the photoreceptor 1. The flying developer discharge preventing member having a length that does not reach the straight line L1 is not limited to the plate-like member 3a as shown in FIG. For example, the block member 3 shown in FIG.

  The developing device 4 shown in FIGS. 8, 13, and 14 is configured such that the lowest point Q of the developer discharge port 94 is higher than the upper vertex P of the supply screw 8. As for the position of the developer discharge port 94, the lowest point Q of the developer discharge port 94 may be at a position lower than the upper vertex P of the supply screw 8 as in the developing device 4 shown in FIG. 15. In the case of the developing device 4 as shown in FIG. 15, the flight is performed so as to prevent the tangent drawn from the lowest point Q of the developer discharge port 94 with respect to the circumference drawn by the end of the supply screw 8 in the cross-sectional direction. A developer discharge preventing member (a plate-like member 3a in FIG. 15) is disposed. By disposing the flying developer discharge preventing member in this way, it is possible to prevent the jumped developer from flying and passing through the developer discharge port 94 in the same manner as in the first or second embodiment.

Example 3
The flying developer discharge preventing members of the first and second embodiments prevent the developer flying mainly in the rotation direction of the supply screw 8 from being discharged from the developer discharge port 94.
In the supply conveyance path 9, the developer flies not only in the rotation direction of the supply screw 8 but also in the axial direction of the supply screw 9. Hereinafter, a third example (hereinafter, “Example 3”) including the characteristic portion of the developing device 4 according to the embodiment , which prevents the developer flying in the axial direction of the supply screw 9 from being discharged. Will be described.
FIG. 16 is an enlarged explanatory view of the vicinity of the downstream end of the supply conveyance path 9 of the developing device 4 according to the third embodiment.
Since the shape of the flying developer discharge preventing member is different from that of the first embodiment and the other configurations are common to the third embodiment, only the differences will be described.

As shown in FIG. 16, the developing device 4 of Example 3 is perpendicular to the conveying direction (arrow S in FIG. 16) of the supply screw 8 that is a developer conveying member as a flying developer discharge preventing member, and An upstream side wall member 38 having a wall surface 38f whose normal line direction is opposite to the arrow S direction is provided upstream of the developer discharge port 94 in the conveying direction of the supply screw 8.
By providing the upstream side wall member 38, the developer T <b> 1 flying in the transport direction of the supply screw 8 from the upstream side in the developer transport direction with respect to the developer discharge port 94 hits the wall surface 38 f of the upstream side wall member 38. As a result, the path of the developer T1 flying in the transport direction in the axial direction of the supply screw 8 toward the developer discharge port 94 can be blocked. For this reason, it is possible to prevent the developer T1 flying in the transport direction from being directly discharged from the developer discharge port 94.

Further, as shown in FIG. 16, the developing device 4 of Example 3 is a flying developer discharge preventing member that is perpendicular to the conveying direction of the supply screw 8 (arrow S in FIG. 16) and has a normal direction. A downstream side wall member 39 having a wall surface 39f that is in the same direction as the arrow S direction is provided on the downstream side in the transport direction of the supply screw 8 with respect to the developer discharge port 94.
By providing the downstream side wall member 39, the developer T <b> 2 that flies in the direction opposite to the conveyance direction of the supply screw 8 from the downstream side in the developer conveyance direction with respect to the developer discharge port 94 is caused by the wall surface 39 f of the downstream side wall member 39. I hit it. As a result, the path of the developer T2 flying in the direction opposite to the transport direction in the axial direction of the supply screw 8 can be blocked. For this reason, it is possible to prevent the developer T2 flying in the direction opposite to the conveyance direction from being directly discharged from the developer discharge port 94.

Further, as shown in FIG. 16, the upstream side wall member 38, which is a wall member, and the downstream side wall member 39, which are the lower ends of the upstream side wall member 38 and the downstream side wall lower end portion 39 e, are located below the lower end of the developer discharge port 94. positioned. By arranging in this way, it is possible to more reliably prevent the developer (T1, T2) flying in the axial direction of the supply screw 8 from being directly discharged from the developer discharge port 94 in a state of flying. .
Further, the shapes of the upstream side wall lower end 38e and the downstream side wall lower end 39e, which are the lower ends of the upstream side wall member 38 and the downstream side wall member 39, are the same as the shape of the bottom surface of the block member 3 of the first embodiment. It becomes R shape along. The upstream side wall lower end part 38e and the downstream side wall lower end part 39e are R-shaped along the shape of the supply screw 8, so that the upstream side wall lower end part 38e and the downstream side wall lower end part 39e can be brought close to the supply screw 8. Become. By bringing the upstream side wall lower end portion 38e and the downstream side wall lower end portion 39e close to the supply screw 8, the developer (T1, T2) flying in the axial direction of the supply screw 8 is directly discharged from the developer discharge port 94. It is possible to prevent the discharge more reliably.
In the case where the developer discharge port 94 is disposed at the downstream end of the supply conveyance path 9 in the developer conveyance direction, even if the wall member is only the upstream side wall member 38, the developer flying in the axial direction of the supply screw 8 is used. However, it can be sufficiently prevented from being discharged directly from the developer discharge port 94.

In the developing device 4 according to the embodiment , the conveyance direction of the supply screw 8 is perpendicular to the conveyance direction of the supply screw 8 on the downstream side of the developer discharge port 94 in the supply conveyance path 9, and the normal direction is opposite to the conveyance direction of the supply screw 8. And a downstream end wall surface that prevents movement of the developer in the transport direction.
FIG. 17 is an explanatory diagram of the downstream end wall surface 9e.
As shown in FIG. 17, a downstream end wall surface 9 e is provided on the downstream side of the developer discharge port 9 in the supply conveyance path 9. The developer discharge port 94 is provided such that the downstream side wall surface 9e is prevented from being transported and stays, and the swell of the developer that has risen covers the developer discharge port 94. By arranging so that the skirt is placed over the developer discharge port 94, the portion of the skirt passes through the developer discharge port 94 when the bulk of the developer that has accumulated and swelled on the upstream side of the downstream end wall surface 9 e increases. Therefore, the developer can be prevented from being clogged at the developer discharge port 94.

  In the first and second embodiments, the end surface of the casing forming the supply conveyance path 9 at the downstream end in the conveyance direction of the supply screw 8 acts as the downstream end wall surface 9e. Moreover, in Example 3, the surface on the back side of the wall surface 39f of the downstream side wall member 39 acts as the downstream end wall surface 9e.

The developing device 4 according to the embodiment includes a supply transport path 9 that is a developer supply transport path in which the developer is transported by a supply screw 8 that is a developer transport screw that transports the developer in a developer supply region of the developer transport path. A developer discharge port 94 is provided therein. A developing roller 5 that is a developer carrying member is disposed on the side (the right side in FIG. 8) on which the wing portion moves upward from below by rotating the supply screw 8. Further, a developer discharge port 94 is arranged on the side (the left side in FIG. 8) on which the wing portion moves downward from above by rotating the supply screw 8. By disposing the developing roller 5 on the side where the blade portion of the supply screw 8 moves upward from below, the developer in the supply conveyance path 9 can be supplied to the supply roller 5 by scooping up from below. The supply capability of the developer to the developing roller 5 is stabilized. Further, by disposing the developer discharge port 94 on the opposite side of the developing roller 5 with the supply screw 8 interposed therebetween, the developer supply / conveyance which is a region for supplying the developer to the developing roller 5 in the axial direction of the supply screw 8. A developer discharge port 94 can be provided in the region α. Thereby, size reduction of the developing device 4 can be achieved.

[ Reference form ]
In the above-described embodiment , the flying developer discharge preventing member is used in order to prevent the developer that has jumped up due to the conveyance of the developer by the supply screw 8 that is a developer conveying member from flying and reaching the developer discharge port 94. The developing device 4 including the above has been described. The configuration for preventing the developer from jumping out and being discharged from the developer discharge port 94 even though the amount of the developer in the developing device 4 has not increased is to suppress the jumping of the developer. May be.
Hereinafter, a configuration for preventing the developer from being discharged even if the amount of the developer in the developing device has not increased will be described as a reference mode by suppressing the developer from jumping.

[ Reference configuration example 1 ]
Then, one eye of Reference example configuration of the developing device 4 of the reference embodiment (hereinafter, referred to as "Reference Configuration Example 1") will be described.
The reference configuration example 1 is different from the configuration of the first embodiment in that the flying developer discharge prevention member is not provided and the shape of the supply screw 8 is different, and the other configurations are common. Therefore, only the differences will be described.
FIG. 18 is an explanatory side sectional view of the developing device 4 of Reference Configuration Example 1 .
As shown in FIG. 18, the developing device 4 of the reference configuration example 1 includes a rotating shaft 8a and a blade portion 8b spirally provided on the rotating shaft 8a, and conveys the developer in the axial direction by rotating. A supply screw 8 which is a developer conveying screw is provided. The outer diameter R2 of the wing portion 8b in the developer discharge area η, which is an area where the developer discharge port 94 is provided in the developer transfer direction in the supply transfer path 9, is the developer transfer direction of the developer discharge area η. It is smaller than the outer diameter R1 of the wing portion 8b on the upstream side.
In the developing device 4 of Reference Configuration Example 1 , the outer diameter R1 of the wing portion 8b on the upstream side in the developer transport direction of the developer discharge region η is φ22 [mm], and the outer diameter of the wing portion 8b in the developer discharge region η. R2 is φ18 [mm].

As in Reference Example 1 , the outer diameter R2 of the wing portion 8b in the developer discharge area η is smaller than the outer diameter R1 of the wing portion 8b on the upstream side in the developer transport direction of the developer discharge area η. The developer conveyance speed in the agent discharge area η can be made slower than other portions. Since the conveyance speed is slow, the momentum due to movement is weakened, and the developer is less likely to jump. Further, since the outer diameter is small, the force of the developer toward the outer diameter direction of the wing portion 8b is weakened, and the developer is less likely to jump. Thus, in the developer discharge area η, the developer can be prevented from jumping due to the rotation of the supply screw 8. This makes it difficult for the splashed developer to reach the developer discharge port 94, prevents the splashed developer from being discharged, and develops the developer even though the amount of developer in the developing device 4 has not increased. It is possible to prevent the agent from being discharged. Therefore, the necessary amount of developer in the developing device 4 can be secured, and the developer can be stably supplied to the latent image carrier.

[ Reference configuration example 2 ]
Next, two eyes of Reference example configuration of the developing device 4 of the reference embodiment (hereinafter, referred to as "Reference Configuration Example 2") will be described.
The reference configuration example 2 differs from the configuration of the reference configuration example 1 in that the shape of the supply screw 8 in the developer discharge region η is different and the other configurations are common, so only the differences will be described.
FIG. 19 is an explanatory side sectional view of the developing device 4 of Reference Configuration Example 2 .
As shown in FIG. 19, the developing device 4 of Reference Configuration Example 2 includes a rotating shaft 8a and a wing portion 8b spirally provided on the rotating shaft 8a, and rotates to convey the developer in the axial direction by rotating. A supply screw 8 which is an agent conveying screw is provided. The pitch width P2 of the blade 8b in the developer discharge area η, which is the area where the developer discharge port 94 is provided in the developer transfer direction in the supply transfer path 9, is the developer transfer direction of the developer discharge area η. It is narrower than the pitch width P1 of the wing portion 8b on the upstream side.

As in Reference Example 2 , the pitch width P2 of the wings 8b in the developer discharge area η is narrower than the pitch width P1 of the wings 8b on the upstream side in the developer transport direction of the developer discharge area η. The developer conveyance speed in the agent discharge area η can be made slower than other portions. Since the conveyance speed is slow, the momentum due to movement is weakened, and the developer is less likely to jump. Thus, in the developer discharge area η, the developer can be prevented from jumping due to the rotation of the supply screw 8. This makes it difficult for the splashed developer to reach the developer discharge port 94, prevents the splashed developer from being discharged, and develops the developer even though the amount of developer in the developing device 4 has not increased. It is possible to prevent the agent from being discharged. Therefore, the necessary amount of developer in the developing device 4 can be secured, and the developer can be stably supplied to the latent image carrier.

[ Reference Configuration Example 3 ]
Next, three eyes of Reference example configuration of the developing device 4 of the reference embodiment (hereinafter, referred to as "Reference Configuration Example 3") will be described.
The reference configuration example 3 differs from the configuration of the reference configuration example 1 in that the shape of the supply screw 8 in the developer discharge region η is different and the other configurations are common, so only the differences will be described.
FIG. 20 is an explanatory side sectional view of the developing device 4 of Reference Configuration Example 3 .
As shown in FIG. 20, the developing device 4 of Reference Configuration Example 3 includes a rotating shaft 8a and a wing portion 8b spirally provided on the rotating shaft 8a. The developing device 4 rotates to convey the developer in the axial direction. A supply screw 8 which is an agent conveying screw is provided. The supply screw 8 in the developer discharge region η, which is a region in which the developer discharge port 94 is provided in the developer transfer direction in the supply transfer path 9, is not provided with the wing portion 8b, but only the rotating shaft 8a.

By not providing the wing portion 8b in the developer discharge area η as in the reference configuration example 3 , it is possible to suppress the developer from jumping up when the supply screw 8 rotates in the developer discharge area η. This makes it difficult for the splashed developer to reach the developer discharge port 94, prevents the splashed developer from being discharged, and develops the developer even though the amount of developer in the developing device 4 has not increased. It is possible to prevent the agent from being discharged. Therefore, the necessary amount of developer in the developing device 4 can be secured, and the developer can be stably supplied to the latent image carrier.

The developing device may be a combination of the configuration described in the embodiment and the configuration described in the reference embodiment .
For example, in the developing device 4 including the block member 3 shown in FIG. 8, a supply screw 8 that does not provide the wings 8b in the developer discharge region η can be used like the supply screw 8 shown in FIG. With such a configuration, it is possible to more reliably prevent the splashed developer from being discharged, and it is possible to discharge the developer in response to an increase in the volume of the developer.

Further, in the one-way circulation developing device 4 including the supply conveyance path 9, the agitation conveyance path 10, and the collection conveyance path 7, the developer that reaches the downstream end in the conveyance direction of the supply conveyance path 9 does not contribute to development. It is an agent. In the one-way circulation developing device 4, it is suitable to discharge the developer increased by the replenishment of the premix toner at the position where the excess developer stays. This is due to the following reason.
Since the collection conveyance path 7 conveys the developer carried on the developing roller 5 and passed through the development region, even if the amount of the developer in the developing device 4 changes, almost no developer is conveyed in the collection conveyance path 7. There is no change, and the developer cannot be discharged due to an increase in the volume of the developer.
As the amount of developer in the developing device 4 increases, the amount of developer to be transported increases and the bulk of the agitation transport path 10 also increases. However, due to the jumping of the developer to be transported or unevenness in the transport amount, the developer is discharged even if the developer amount does not increase, and the required amount of developer cannot be delivered to the supply transport path 9. is there. For this reason, it is not appropriate to discharge the developer due to the increase in the volume of the developer in the stirring conveyance path 10. Further, the configuration of discharging in the middle of the supply conveyance path 9 may increase the volume of the developer even if the amount of the developer in the developing device 4 is not increased, and the downstream side in the conveyance direction from the discharged position. Is not suitable because the developer may be insufficient.
For this reason, the one-way circulating developing device 4 discharges the developer increased by replenishing the premix toner at the position where the developer that reaches the downstream end in the transport direction of the supply transport path 9 stays. Is suitable.

In the developing device 4 of the embodiment, the excessive opening 92 is larger than the developer discharge port 94, but the developer discharge port 94 may be larger than the excessive opening 92.
Further, in the above-described embodiment, FIG. 4 shows a configuration in which the developer discharging means discharges a part of the developer when the volume of the developer near the downstream end in the transport direction of the supply transport path 9 exceeds a predetermined height. The configuration applied to the developing device 4 having the configuration shown has been described. The configuration to which the characterizing portion of the present invention can be applied is not limited to that shown in FIG. 4, but can be similarly applied to the developing device 4 having the configuration shown in FIGS.
In the above-described embodiment, the developing device using the two-component developer composed of the carrier and the toner as the developer has been described. The developing device to which the feature of the present invention is applied is not limited to a developing device using a two-component developer. A developing device using a one-component developer can be used as long as the developer is replenished by the developer replenishing unit and the developer discharging unit discharges the increased amount of developer in the developing device. Is applicable.

As described above, according to the embodiment, as in Example 1, as a flying developer discharge prevention member for blocking a path developer flying is toward the developer discharge port 94 by the transport operation of the supply screw 8 is a developer conveying member The blocking member 3 prevents the jumped developer from reaching the developer discharge port 94 and being discharged, and the developer amount in the developing device 4 is not increased. Can be prevented from being discharged. Therefore, the necessary amount of developer in the developing device 4 can be secured, and the developer can be stably supplied to the latent image carrier.
Further, by providing the block member 3 so as to block the straight line L1 connecting the lowest point Q of the developer discharge port 94 and the upper vertex P of the wing portion 8b of the supply screw 8, from the vicinity of the upper vertex P of the supply screw 8. It is possible to prevent the developer flying in the tangential direction of the circumference drawn by the wing from passing through the developer discharge port 94. Further, as shown in FIG. 8, since the block member 3 is a member arranged so as to block the straight line L1 from the casing of the developing device 4 above the supply conveyance path 9, the development that flies above the straight line L1. The path (arrow T in FIG. 22) toward the developer discharge port 94 can be blocked. Thereby, it is possible to more reliably prevent the flying developer from reaching the developer discharge port 94.
Further, by using an elastic material such as sponge as the material of the block member 3, when the volume of the developer increases and reaches the lower surface of the block member 3, the volume of the developer further increases. The block member 3 is deformed. Due to this deformation, it is possible to prevent the stress of the developer from increasing due to the lower surface of the block member 3 suppressing the developer.
Further, as in the second embodiment, the flying developer discharge preventing member is a member in which a plurality of plate-like members 3a are arranged at intervals, so that the amount of developer in the developing device 4 increases, and the developer is increased. When the bulk of the toner increases, the developer corresponding to the increased bulk enters the gap between the plate-like members 3a. As a result, it is possible to reliably eliminate the effect of the developer splash without applying pressure to the developer, and to guide only the increased amount of developer to the developer discharge port 94.
Further, as in the third embodiment, the flying developer discharge preventing member is perpendicular to the conveying direction of the supply screw 8 which is a developer conveying member, and the normal line direction is opposite to the conveying direction of the supplying screw 8. By providing the upstream side wall member 38, which is a wall member provided with the wall surface 38f, on the upstream side in the transport direction of the supply screw 8 with respect to the developer discharge port 94, it flew in the transport direction in the axial direction of the supply screw 8. The developer T1 can be prevented from being discharged directly from the developer discharge port 94.
Further, as in the third embodiment, the flying developer discharge preventing member is perpendicular to the conveying direction of the supply screw 8 that is a developer conveying member, and the normal direction thereof is the same as the conveying direction of the supply screw 8. By providing the downstream side wall member 39, which is a wall member provided with the wall surface 39f, on the downstream side in the transport direction of the supply screw 8 with respect to the developer discharge port 94, the transport direction of the supply screw 8 is opposite to the transport direction. It is possible to prevent the developer T2 flying in the direction from being discharged directly from the developer discharge port 94.
Further, on the downstream side of the developer discharge port 94 in the supply conveyance path 9 that is a developer conveyance path, the supply screw 8 that is a developer conveyance member is perpendicular to the conveyance direction of the supply screw 8 and the normal direction thereof is the supply screw. 8 is provided in a direction opposite to the conveyance direction 8 and includes a downstream end wall surface 9e that prevents the developer from moving in the conveyance direction, and the developer swelled by the downstream end wall surface 9e is blocked by the downstream end wall surface 9e. Thus, by providing the developer discharge port 94, it is possible to prevent the developer from being clogged at the developer discharge port 94.
Further, the upstream side wall member 38 that is a wall member and the downstream side wall member 39 that are the lower ends of the upstream side wall member 38 and the downstream side wall lower end portion 39e are positioned below the lower end of the developer discharge port 94, thereby supplying the supply screw. It is possible to more reliably prevent the developer (T1, T2) flying in the axial direction of 8 from being discharged directly from the developer discharge port 94 in a state of flying.
Further, the developer transport member in the supply transport path 9 includes a rotation shaft and a wing portion spirally provided on the rotation shaft, and rotates to developer transport screw that transports the developer in the direction of the rotation shaft. By being 8, the developer can be transported in the supply transport path 9 with a simple configuration.
Further, the upstream side wall member 38 that is a flying developer discharge preventing member on the plane perpendicular to the conveyance direction of the supply screw 8 that is the developer conveying screw, and the upstream side wall lower end 38e that is the lower end of the downstream side wall member 39 and the lower end of the downstream side wall. By making the shape of the portion 39e an R shape along the shape of the upper part of the wing portion of the supply screw 8, the developer (T1, T2) flying in the axial direction of the supply screw 8 is in a state where the developer has jumped. Direct discharge from the discharge port 94 can be prevented more reliably.
Further, the developer is discharged into a supply conveyance path 9 that is a developer supply conveyance path where the developer is conveyed by a supply screw 8 that is a developer conveyance screw that conveys the developer in the developer supply region α of the developer conveyance path. A developer roller 5 that is a developer carrying member is disposed on the side of the outlet 94 and the supply screw 8 is rotated so that its wings move upward from below. Supply is stable. Further, the developer discharge port 94 is disposed on the side where the wing portion moves downward from above by rotating the supply screw 8, that is, on the opposite side of the developing roller 5 with the supply screw 8 interposed therebetween. Thus, the developing device 4 can be downsized.
Further, according to the reference mode , as in Reference Configuration Example 1 , the rotary shaft 8a and the blade portion 8b spirally provided on the rotary shaft 8a are provided, and the developer is conveyed in the direction of the rotary shaft by rotating. The outer diameter R2 of the blade 8b in the developer discharge region η, which is a region provided with the supply screw 8 and provided with the developer discharge port 94 in the developer transfer direction in the supply transfer path 9 which is the developer transfer path, It is smaller than the outer diameter R1 of the wing portion 8b on the upstream side in the developer transport direction of the developer discharge area η. For this reason, the conveyance speed of the developer within the developer discharge area η can be made slower than the other portions. Since the conveyance speed is slow, the momentum due to movement is weakened, and the developer is less likely to jump. Further, since the outer diameter is small, the force of the developer toward the outer diameter direction of the wing portion 8b is weakened, and the developer is less likely to jump. Thus, in the developer discharge area η, the developer can be prevented from jumping due to the rotation of the supply screw 8. This makes it difficult for the splashed developer to reach the developer discharge port 94, prevents the splashed developer from being discharged, and develops the developer even though the amount of developer in the developing device 4 has not increased. It is possible to prevent the agent from being discharged. The necessary amount of developer in the developing device 4 can be ensured, and the developer can be stably supplied to the latent image carrier.
Further, as in Reference Configuration Example 2 , the pitch width P2 of the wings 8b in the developer discharge area η is set to be narrower than the pitch width P1 of the wings 8b on the upstream side in the developer transport direction of the developer discharge area η. By doing so, similarly to the reference configuration example 1 , the transport speed of the developer in the developer discharge area η can be made slower than the other portions. For this reason, similarly to the reference configuration example 1 , a necessary amount of developer in the developing device 4 can be secured, and the developer can be stably supplied to the latent image carrier.
Also, as in the Reference example configuration 3, the supply screw 8 in the developer discharge region η is not provided with the blade portion 8b, by only Nasr rotation axis 8a, in the same manner as in Reference Configuration Example 1, the developer discharge region The developer conveying speed within η can be made slower than other portions. For this reason, similarly to the reference configuration example 1 , a necessary amount of developer in the developing device 4 can be secured, and the developer can be stably supplied to the latent image carrier.
Further, the developing device 4 of the configuration of the embodiment, by applying the supply screw 8 that the developing apparatus 4 is provided with the configuration of the reference embodiment, prevents more reliably jumping developer is discharged, the developing device 4 It is possible to prevent the developer from being discharged even though the amount of the developer is not increased.
In addition, the developer is discharged at a position where the developer that reaches the downstream end in the transport direction of the supply transport path 9 of the one-way circulating developing device 4 including the supply transport path 9, the stirring transport path 10, and the recovery transport path 7 is discharged. As a result, the developer increased by the replenishment of the premix toner can be appropriately discharged.
Further, by providing the developing device 4 as the developing means of the copying machine as the image forming apparatus, it is possible to prevent the occurrence of abnormal images such as missing images while extending the life of the developing means by replacing the developer. Image formation can be performed.

[Modification]
The developing device 4 of the embodiment and the reference embodiment has a configuration in which the supply conveyance path 9 is provided above the stirring conveyance path 10 and the collection conveyance path 7. The developing device 4 to which the configuration for saving the space above the developing device 4 as shown in FIG. 4 is applicable is not limited to this configuration. Hereinafter, as a modification, a developing device in which three developer conveyance paths including a supply conveyance path 9, an agitation conveyance path 10, and a collection conveyance path 7 are provided at substantially the same height will be described. Since the configuration other than the shape of the developing device 4 is the same as that of the embodiment , only the developing device 4 which is a difference will be described.

FIG. 21 is a schematic configuration diagram of the developing device 4 according to a modification.
As shown in FIG. 21, the surface of the photoreceptor 1 is charged by the scorotron charger 103 while rotating in the direction of arrow G in the figure. The charged surface of the photoreceptor 1 is supplied with toner from the developing device 4 to a latent image on which an electrostatic latent image is formed by laser light emitted from an exposure device (not shown), thereby forming a toner image.

The developing device 4 has a developing roller 5 as a developer carrying member for supplying toner to the latent image on the surface of the photoreceptor 1 while moving the surface in the direction of arrow I in the drawing. Further, a supply screw 8 is provided as a supply conveyance member that conveys the developer in the depth direction of FIG. 21 while supplying the developer to the developing roller 5.
A developing doctor 12 as a developer regulating member for regulating the developer supplied to the developing roller 5 to a thickness suitable for development is provided on the downstream side of the surface moving direction from the portion facing the supply screw 8 of the developing roller 5. ing.
The developed developer that has passed through the developing section is collected downstream from the developing section, which is the facing portion of the developing roller 5 with respect to the photoconductor 1, and the collected developer is collected in the same direction as the supply screw 8. A recovery screw 6 is provided as a recovery transport member for transporting to the front. A supply conveyance path 9 having a supply screw 8 and a collection conveyance path 7 having a recovery screw 6 are arranged below the developing roller 5 in parallel. The two conveyance paths of the supply conveyance path 9 and the collection conveyance path 7 are partitioned by a second partition wall 134 as a partition member.

  The developing device 4 is provided with a stirring conveyance path 10 in parallel with the supply conveyance path 9 on the opposite side of the collection conveyance path 7. The agitating and conveying path 10 includes an agitating screw 11 serving as an agitating and conveying member that conveys the developer to the near side in the figure, which is in the opposite direction to the supply screw 8 while agitating the developer. The supply conveyance path 9 and the stirring conveyance path 10 are partitioned by a first partition wall 133 as a partition member. Both ends of the first partition wall 133 on the front side and the back side in the figure are openings, and the supply conveyance path 9 and the agitation conveyance path 10 communicate with each other. The excess developer that is supplied into the supply conveyance path 9 and is not used for development and is conveyed to the downstream end in the conveyance direction of the supply conveyance path 9 and the collected development conveyed to the downstream end in the conveyance direction of the collection conveyance path 7 by the collection screw 6 The agent is supplied to the stirring conveyance path 10. The agitating and conveying path 10 agitates the supplied excess developer and the recovered developer and conveys them to the downstream side in the conveying direction of the agitating screw 11. Then, the developer is supplied into the supply conveyance path 9 on the upstream side in the conveyance direction of the supply screw 8 from the supply opening 91 provided in the first partition wall 133.

The second partition wall 134 has an opening at the end in the drawing, which is the most downstream side in the transport direction of the recovery screw 6, and the supply transport path 9 and the recovery transport path 7 communicate with each other. The three conveying paths are in communication with the downstream end in the conveying direction of the collection screw 6, the downstream end in the conveying direction of the supply screw 8, and the upstream end in the conveying direction of the stirring screw 11.
Then, the recovered developer transported to the downstream end in the transport direction of the recovery transport path 7 is transferred to the supply transport path 9. Further, the collected developer and the developer that has not been supplied to the developing roller 5 that is conveyed by the supply screw 8 are transferred to the communicating agitating and conveying path 10.
In the agitating and conveying path 10, the agitating screw 11 agitates and conveys the collected developer, the surplus developer, and the toner replenished as necessary in the transfer unit in the direction opposite to the developer in the collecting and conveying path 7 and the supply conveying path 9. . Then, the agitated developer is transferred to the upstream side in the conveyance direction of the supply conveyance path 9 communicating with the downstream side in the conveyance direction. A toner concentration sensor 127 is provided below the agitating and conveying path 10, and a toner replenishment control device (not shown) is operated by sensor output to replenish toner from a toner bottle (not shown) to a transfer unit. Yes.
The casing of the developing device 4 includes an integrally formed lower casing 112 and upper casing 113 that are divided into upper and lower portions at the shaft portions of three conveying screws. The first partition wall 133 is a part of the lower casing 112, and the second partition wall 134 is held by the upper casing 113 and mated with the lower casing 112.
As the above-described toner replenishment control device, a system using a known MONO pump can be employed. According to this method, there are few restrictions on the installation location of the toner cartridge, which is advantageous for space allocation in the image forming apparatus. Further, since the toner can be replenished in a timely manner, it is not necessary to provide a large toner storage space in the developing device 4, and the developing device 4 can be downsized.

As shown in FIG. 21, the screw apex 114 of the supply screw 8, which is the uppermost part of the supply member, is disposed below the rotation center 115 of the developing roller 5. In the developing device 4, an angle θ1 between a straight line connecting the rotation center 115 of the developing roller 5 and the screw apex 114 and a horizontal straight line passing through the rotation center 115 is set to 30 [°]. The angle θ1 depends on the diameter of the supply screw 8, but is preferably 10 [°] to 40 [°] in view of the layout because the developing device 4 is downsized.
The developer is supplied to the developing roller 5 by the magnetic poles provided in the developing roller 5 attracting the magnetic carrier in the developer. As described above, by arranging the screw apex 114 to be lower than the rotation center 115 of the developing roller 5, the weight of the developer does not affect the amount of the developer supplied to the developing roller 5, and the magnetic force The size contributes to the developer supply amount. Accordingly, since the developer is reliably supplied from above the developer conveyed in the supply conveyance path 9, the developing roller 5 can be used even if the bulk of the developer in the supply conveyance path 9 is not uniform in the conveyance direction of the supply screw 8. An appropriate amount of developer can be supplied.

In the conventional developing device in which the three developer transport paths are provided at the same height, the supply opening for delivering the developer from the stirring transport path 10 to the supply transport path 9 is provided outside the development region width α. As a result, the agitation conveyance path 10 and the supply conveyance path 9 are in a state where the upstream end portion in the conveyance direction of the supply conveyance path 9 protrudes as compared with the developing roller 5 and the collection conveyance path 7.
In the developing device 4 of the modified example, since the supply opening is provided in the development region width α, the portion where the agitating conveyance path 10 and the supply conveyance path 9 protruded compared to the developing roller 5 and the collection conveyance path 7 is eliminated. Thus, space saving of the developing device 4 can be achieved.
Further, like the developing device 4 of the modified example, by providing the collection conveyance path 7, the stirring conveyance path 10, and the supply conveyance path 9 at substantially the same height, the stress applied to the developer is reduced, and the length of the developer is increased. Life can be extended. That is, by providing the three developer transport paths at the same height, it is not necessary to lift the developer upward in the developer transport path, so that stress applied to the developer can be reduced. As a result, the deterioration of the developer can be suppressed and stable image quality can be maintained.

DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Discharge conveyance path 2a Discharge conveyance screw 4 Developing apparatus 5 Developing roller 6 Collection screw 7 Collection conveyance path 8 Supply screw 8a Rotating shaft 8b Feather part 9 Supply conveyance path 10 Stirring conveyance path 11 Stirring screw 12 Developer doctor 14 Tension Roller 15 Drive roller 16 Secondary transfer backup roller 17 Intermediate transfer unit 18 Process cartridge 20 Image forming unit 21 Optical writing unit 22 Secondary transfer device 23 Stretching roller 24 Paper transport belt 25 Fixing device 26 Fixing belt 27 Pressure roller 90 Belt cleaning device 91 Supply opening 92 Surplus opening 93 Recovery opening 94 Developer discharge port 95 Toner supply port 100 Printer unit 110 Intermediate transfer belt 133 First partition wall 134 Second partition wall 135 Partition wall

JP 2005-292511 A

Claims (12)

A developer carrying member that rotates by carrying a developer on the surface, and supplies toner to the latent image on the surface of the latent image carrying member at a position facing the latent image carrying member;
A developer transport member that transports the developer while supplying the developer to the developer carrier in a developer supply region that includes a developer transport member that transports the developer and supplies the developer to the developer carrier; ,
Developer replenishing means for replenishing the developer in the developer transport path,
A developer discharge port for discharging the developer to the outside of the apparatus is provided in the developer conveyance path at a predetermined height at a position where the volume of the developer increases or decreases according to the increase or decrease of the developer amount in the entire developer conveyance path. In the developing device
A flying developer discharge preventing member that blocks the path of the developer flying by the transporting operation of the developer transporting member toward the developer discharge port ;
The developer conveying member is a developer conveying screw that includes a rotating shaft and a blade provided spirally on the rotating shaft, and conveys the developer in the direction of the rotating shaft by rotating.
The flying developer discharge preventing member is a protruding member protruding downward from a casing above the developer conveying path,
Projecting the shape of the lower end of the member in a plane perpendicular to the conveying direction of the developer conveying screw, a developing device according to claim R shape der Rukoto along the top of the shape of the wing portion of the developer conveying screw. The developing device according to claim 1.
Developing apparatus is characterized in that a said flight developer discharge prevention member so as to close the straight line connecting the upper vertices of the wing portion of the lowest point and the developer conveying screw of the upper Symbol developer discharge port. The developing device according to claim 1 or 2,
The developing device, wherein the flying developer discharge preventing member is made of an elastic material. The developing device according to claim 1, 2 or 3,
2. The developing device according to claim 1, wherein the flying developer discharge preventing member includes a plurality of plate-like members arranged at intervals. The developing device according to claim 1, 2, 3 or 4,
As the flying developer discharge preventing member, a wall member provided with a wall surface that is perpendicular to the transport direction of the developer transport member and whose normal direction is opposite to the transport direction of the developer transport member, A developing device provided on the upstream side in the transport direction of the developer transport member with respect to the developer discharge port . The developing device according to claim 1, 2, 3, 4 or 5.
The outer diameter of the hub of the developer discharge region for the developer conveying direction of the developer conveying path is a region provided with the developer discharge port, the developer conveying direction upstream side of the developer discharging region A developing device having an outer diameter smaller than that of the wing portion. The developing device according to claim 1, 2, 3, 4 or 5.
Pitch width of the wing portion of the developer discharge region for the developer conveying direction of the developer conveying path is a region provided with the developer discharge port, the developer conveying direction upstream side of the developer discharging region A developing device characterized by being narrower than the pitch width of the wings. The developing device according to claim 1, 2, 3, 4 or 5.
The developer conveying screw of the developer discharge region for the developer conveying direction of the developer conveying path is a region provided with the developer discharge port is developing apparatus is characterized by not comprising the wing portion. The developing device 請 Motomeko 7 or 8,
The developer discharge port is provided in the developer supply conveyance path in which the developer is conveyed by a supply screw that is the developer conveyance screw that conveys the developer in the developer supply region of the developer conveyance path,
The developer carrying member is disposed on the side of the side where the wing part moves upward from below by rotating the supply screw,
2. A developing device according to claim 1, wherein the developer discharge port is disposed on a side of a side where the blade portion moves downward from above by rotating the supply screw. In the claims 1,2,3,4,5,6,7, the developing device 9 was 8 or,
A two- component developer comprising a magnetic carrier and a toner is provided as a developer,
A supply conveyance path provided with a supply conveyance member for conveying the developer along the axial direction of the developer carrier and supplying the developer to the developer carrier;
The developer recovered from the developer carrier after passing through the portion facing the latent image carrier is transported along the axial direction of the developer carrier and in the same direction as the supply transport member. A collection conveyance path provided with a collection conveyance member;
Excess developer transported to the most downstream side in the transport direction of the supply transport path without being used for development, and recovery recovered from the developer carrier and transported to the most downstream side in the transport direction of the recovery transport path An agitating / conveying member that receives the supply of the developer and conveys in the direction opposite to the supply / conveying member while stirring the surplus developer and the recovered developer along the axial direction of the developer carrying member. A stirring and conveying path for supplying the stirred developer after stirring to the supply and conveying path,
The developer transport path is constituted by three developer transport paths: the recovery transport path, the supply transport path, and the stirring transport path.
A developing device comprising three developer transport members, the recovery transport member, the supply transport member, and the agitation transport member, as the developer transport member. The developing device according to claim 10 .
The developing device, wherein the developer discharge port is disposed in the vicinity of the downstream end in the developer transport direction of the supply transport path. At least a latent image carrier;
Charging means for charging the surface of the latent image carrier;
Latent image forming means for forming an electrostatic latent image on the latent image carrier;
In an image forming apparatus having developing means for developing the electrostatic latent image into a toner image,
As developing means, claim 1,2,3,4,5,6,7,8,9,1 0 or an image forming apparatus which comprises using a developing device according to 11.

Images