JP5493614B2 - Developing device and image forming apparatus - Google Patents

Description

  The present invention relates to a developing device and an image forming apparatus, and more particularly to a two-component developer supply mechanism.

  In an image forming apparatus such as a copying machine, a printer, a facsimile machine, or a printing machine, an electrostatic latent image formed on a photosensitive member as a latent image carrier is subjected to visible image processing by a developing device, and the visible image is converted into a sheet. A recording output can be obtained by transferring to the above.

  As a developer used for development, there is a two-component developer obtained by mixing a toner and a carrier in addition to a one-component developer containing only magnetic or non-magnetic toner.

  The two-component developer is composed of a toner and a carrier that carries the toner, and the toner can be electrostatically attracted to the electrostatic latent image on the photosensitive member by charging the toner by a frictional charging effect that occurs during stirring and mixing. It is said.

  In the developing device, a developing sleeve as a developer carrying member for supplying developer toward the electrostatic latent image on the photosensitive member by causing the developer to rise on the peripheral surface by magnetic force, and agitating and mixing the developing sleeve A configuration including a stirring member such as a screw auger for supplying a developer is known. The developer carried on the developing sleeve is supplied to the electrostatic latent image on the photosensitive member after a carrying amount (layer thickness) is defined by a regulating member such as a doctor blade.

  On the other hand, in developing devices used for visible image processing of electrostatic latent images, in recent years, there has been a demand for higher speeds. For this reason, there is a case where the linear speed of the photosensitive drum is increased. .

  In order to increase the speed of the photosensitive drum, it is desired not to cause insufficient supply of the developer. For this purpose, a configuration in which a plurality of developing sleeves for supplying the developer containing toner of the same color is provided. Has been proposed (for example, Patent Document 1).

  In Patent Document 1, as shown in FIG. 18, two developing sleeves are juxtaposed in the gravitational direction along the circumferential direction of the photosensitive drum, and the developing is located upstream in the moving direction of the photosensitive drum, that is, above in the gravitational direction. In the developing tank in which the sleeve is accommodated, a new toner replenishment section and a developer supply screw are arranged, and the developer is supplied to the developing sleeve at this position, while the photosensitive drum moves in the downstream direction. At the side, that is, the position where the developing sleeve positioned below in the direction of gravity is accommodated, the developer is transferred from the developing sleeve positioned above and the developing process is performed again. FIG. 19 shows the flow of the developer in the developing device shown in FIG.

  As a configuration in which a plurality of developing sleeves are juxtaposed in the direction of gravity along the circumferential direction of the photosensitive drum, a unit capable of developing the same color image, each including a developing sleeve and a developer supply and stirring member, is provided. (For example, patent document 2). FIG. 20 shows the developing device disclosed in Patent Document 2.

  Further, separately from this, the developing sleeves are juxtaposed in the gravitational direction with respect to the circumferential direction of the photosensitive drum, the developer is divided between the developing sleeves, and the layer thickness of the developer in each developing sleeve is defined. Using a configuration in which a blade is arranged, the developer from the supply member is supplied to the developing sleeve positioned below the gravity direction, and the developer that has moved on the developing sleeve is divided by the doctor blade and positioned above the gravity direction. A developing device that is supplied toward the developing sleeve is proposed (for example, Patent Document 3). FIG. 21 shows the developing device disclosed in Patent Document 3.

  In the developing devices disclosed in each of the above patent documents, a developer sleeve as a developer carrying member, a supply member for supplying the developer to the developer sleeve, and the developer from the developer sleeve are collected and mixed by stirring. Thereafter, a recovery member for supplying the developer to the supply member is required again.

  However, in order to arrange such members together, a certain amount of installation space is required. In particular, although the developing sleeve is disposed at a position closest to the photosensitive member, a member for collecting the developer returning from the developing sleeve is provided at a position farthest from the photosensitive member, so that the developer conveyance process is long. Therefore, it is inevitable to increase the size of the developing device including the collection unit.

In recent years, since there has been a demand for miniaturization of image forming apparatuses, the installation space for each apparatus in the image forming apparatus is often limited. For this reason, it is necessary to stir and mix the developer collected from the developing sleeve. The space required may not be sufficient.
If the developer with insufficient stirring and mixing is supplied again to the developing sleeve, it causes insufficient density and abnormal images.

  On the other hand, the developer recovered by the recovery unit is intended to be returned from each developing sleeve. Since such a developer does not have a constant concentration and supply amount due to toner consumption, there is a problem in stability of image density when it is supplied again to the developing sleeve. For this reason, it is necessary to supply the developer returned to the collection unit to the developing sleeve after replenishing toner and stirring and mixing.

  However, in such a configuration, the movement of the developer is in one direction from the developing sleeve toward the collecting unit, and the supply amount must be increased to compensate for the shortage of developer supplied to the developing sleeve. There is a problem that it must not. Such a defect includes a new problem of increasing the load on the driving source used for transporting the developer.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a developing device and an image forming apparatus having a configuration capable of preventing problems with the above-described conventional developing device, in particular, an increase in the size of the configuration and an increase in the developer circulation amount. There is.

In order to achieve the above object, the present invention comprises the following arrangement.
(1) A developing device including a developer carrier for supplying a developer to the electrostatic latent image formed on the image carrier,
A plurality of the developer carriers are provided in the direction of gravity along the moving direction of the image carrier, and each includes a developer supply unit and a developer carrying amount regulating member,
A collection unit is provided at a position where developers from the plurality of developer carriers are collected,
Wherein the recovery unit, the developer supply unit is used et is a configuration in which the developer is agitated and mixed via the recovery unit is pneumatic conveying independently for each developer supplying unit is provided A developing device.
(2) In the developing device described in (1),
The means for agitating and mixing the developer includes a plurality of agitation units connected to each developer supply unit that constitutes the recovery unit, and the agitation unit contains the developer recovered from the recovery unit. A configuration for supplying toner according to a result of detecting the toner density and a configuration for stirring and mixing the supplied toner and the developer are provided, and the developer that has been stirred and mixed is conveyed toward the developer supply unit. developing apparatus is characterized in that.
(3) In the developing device described in (2),
A first agitation unit corresponding to one of the agitation units is a first agitation corresponding to one of the developer supply units as a configuration for conveying the agitated and mixed developer to each of the developer supply units. A first supply conveyance path for connecting to the developer supply unit, and a second developer corresponding to the other one of the developer supply unit and a second stirring unit corresponding to the other one of the stirring unit A second supply transport path for connecting to the supply section; a first recovery transport path for connecting a recovery position of the second developer supply section to the first stirring section; and the first And a second collection conveyance path for connecting the collection position of the developer supply section to the second stirring section .
(4) In the developing device described in (3),
The second stirring unit connected to the collection position of the first developer supply unit via the second transport path detects deterioration of the developer collected from the first developer supply unit. A developing device characterized in that means for carrying out the processing is provided .
(5) An image forming apparatus using the developing device according to any one of (1) to (4) .

  According to the present invention, since the developer supply unit used for supplying the developer to the developer carrying member is used as the developer recovery unit, the previously required recovery unit is unnecessary. be able to. Thereby, the enlargement of a structure can be prevented.

  Further, according to the present invention, the developer supply unit that is provided adjacent to the developer carrier becomes the recovery unit. Therefore, unlike the conventional configuration, the developer is separated from the developer carrier and the developer supply unit. Can be circulated between. Thereby, unlike the case where the developer supplied with toner is supplied from a different place from the developer collected from the developer carrier, the circulation amount of the developer can be reduced.

1 is a cross-sectional view illustrating a configuration of an image forming apparatus using a developing device according to an embodiment of the present invention. FIG. 2 is a schematic diagram for explaining the configuration and operation of a developing device used in the image forming apparatus shown in FIG. 1. FIG. 2 is a diagram for explaining an example of an overall configuration related to a developer supply mechanism including the developing device shown in FIG. 1. FIG. 4 is a schematic cross-sectional view for explaining an internal configuration of a developer container used in the developer supply mechanism shown in FIG. 3. FIG. 3 is a schematic diagram illustrating one of developer conveyance modes in the configuration illustrated in FIG. 2. FIG. 5 is a schematic diagram showing another one of developer conveyance modes in the configuration shown in FIG. 2. FIG. 4 is a diagram for explaining a partial modification of the configuration of the developer supply mechanism shown in FIG. 3. It is a figure which shows the change of the developing agent density | concentration of the developing roller in the structure shown in FIG. FIG. 8 is a schematic diagram for explaining a part of a developer conveyance path in the configuration illustrated in FIG. 7. FIG. 8 is a schematic diagram illustrating one of developer conveyance modes in the configuration illustrated in FIG. 7. FIG. 8 is a schematic diagram illustrating another developer transport mode in the configuration illustrated in FIG. 7. It is a schematic diagram for demonstrating another Example of this invention. It is a schematic diagram for demonstrating one structure of the developer accommodating part used for the Example shown in FIG. It is a schematic diagram for demonstrating the partial modification of the structure shown in FIG. FIG. 15 is a schematic diagram showing one form of developer transport in the configuration shown in FIG. 14. FIG. 15 is a schematic diagram showing another one of the developer conveyance modes in the configuration shown in FIG. 14. FIG. 14 is a schematic diagram for explaining a modification example regarding one configuration of the developer accommodating portion illustrated in FIG. 13. It is a schematic diagram for demonstrating one of the prior art examples in a developing device. It is a schematic diagram for demonstrating the flow of the developer by the developing device shown in FIG. It is a schematic diagram for demonstrating another structure of the prior art example in a developing device. It is a schematic diagram for demonstrating another structure of the prior art example in developing measures.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
FIG. 1 shows an image forming apparatus using a developing device according to an embodiment of the present invention , and the image forming apparatus shown in FIG. 1 is a tandem full-color printer. The present invention is not limited to this, and can be applied to a copying machine, a facsimile machine, and the like.

  In the image forming apparatus shown in FIG. 1, each color (yellow, magenta, cyan, black) faces the lower surface of an intermediate transfer belt 10A as an unfixed image carrier provided in the intermediate transfer unit 10 in the apparatus main body 100. ) Corresponding to the image forming units 6Y, 6M, 6C, and 6K.

  These image forming units 6Y, 6M, 6C, and 6K have the same structure except that the color of the toner used in the image forming process is different. In the following description, only the numerical symbols common to the image forming units will be described, and the alphabetic symbols indicating the toner colors will be omitted.

  Each image forming unit 6 includes a drum-shaped photosensitive member 1 (hereinafter referred to as a photosensitive drum) as a latent image carrier, a charging unit 2, a developing device 3, and a cleaning unit 4 disposed around the photosensitive drum 1. Etc.

  An image forming process (charging process, exposure process, developing process, transfer process, cleaning process) is performed on the photosensitive drum 1, and a desired toner image is formed on the photosensitive drum 1.

  The photosensitive drum 1 is rotationally driven in the clockwise direction in the drawing by a driving unit (not shown), and the surface is uniformly charged at the position of the charging means 2 (charging process).

  The surface of the photosensitive drum 1 reaches an irradiation position of a laser beam emitted from an exposure unit (not shown), and an electrostatic latent image is formed by exposure scanning at this position (exposure process). When the position reaches this position, a visible image is processed by the toner contained in the developer supplied therefrom, and the development process is executed.

  The surface of the photosensitive drum 1 carrying the toner image subjected to the visible image processing in the developing process reaches a position facing the intermediate transfer belt 10A and the primary transfer bias roller 5, and at this position on the photosensitive drum 1. The toner image is transferred onto the intermediate transfer belt 10A (primary transfer step).

  After the transfer, the surface of the photosensitive drum 1 reaches a position facing the cleaning unit 4, and untransferred toner remaining on the photosensitive drum 1 is collected at this position (cleaning step). After cleaning, the potential of the surface of the photosensitive drum 1 is initialized by a neutralizing roller (not shown). By passing through such steps, a series of image forming processes performed on the photosensitive drum 1 is completed.

  The image forming process described above is performed at the time of forming a single image of only a monochrome image and at the time of forming a full color image. At the time of forming a full color image, each of the four image forming units 6Y, 6M, 6C, and 6K shown in FIG. Each step is performed. That is, a laser beam based on image information from an exposure unit (optical writing device) (not shown) disposed below the image forming unit is applied to the photosensitive drums of the image forming units 6Y, 6M, 6C, and 6K. Irradiated toward. Thereafter, the toner images of the respective colors formed on the respective photosensitive drums through the developing process are transferred onto the intermediate transfer belt 10A in an overlapping manner. Thus, a color image is formed on the intermediate transfer belt 10A.

  Each of the four primary transfer bias rollers 5Y, 5M, 5C, and 5K sandwiches the intermediate transfer belt 10A between the photosensitive drums 1Y, 1M, 1C, and 1K to form a primary transfer nip. The primary transfer bias rollers 5Y, 5M, 5C, and 5K are applied with a transfer bias having a polarity opposite to the polarity of the toner.

  The intermediate transfer belt 10A travels in the direction of the arrow and sequentially passes through the primary transfer nips of the primary transfer bias rollers 5Y, 5M, 5C, and 5K. Thus, the toner images of the respective colors on the photosensitive drums 1Y, 1M, 1C, and 1K are primarily transferred while being superimposed on the intermediate transfer belt 10A.

  The intermediate transfer belt 10A on which the toner images of the respective colors are transferred in a superimposed manner reaches a position facing the secondary transfer roller 7 as a secondary transfer unit. The color toner image formed on the intermediate transfer belt 10A is collectively transferred onto a transfer sheet P as a recording medium conveyed to the secondary transfer nip position.

  A plurality of transfer sheets P are stored in a paper supply unit 8 disposed in the lower part of the apparatus main body 100, and are separated and fed one by one by a paper supply roller 9. The fed transfer paper P is temporarily stopped by the registration roller pair 10, and after the oblique deviation is corrected, it is conveyed toward the secondary transfer nip by the registration roller pair 10 at a predetermined timing. As described above, a desired color image is transferred onto the transfer paper P at the secondary transfer nip.

The transfer paper P on which the color image is transferred at the position of the secondary transfer nip is conveyed to the fixing unit 11 where the color image transferred to the surface is fixed by heat and pressure generated by the fixing roller and the pressure roller. The
After the fixing, the transfer paper P is discharged as an output image to the paper discharge unit 100A formed on the upper surface of the apparatus main body 100 by the paper discharge roller pair 12 and stacked. Thus, a series of image forming processes in the image forming apparatus is completed. In FIG. 1, reference numeral 13 denotes a cleaning device for the intermediate transfer belt 10A.

  FIG. 2 is a schematic diagram for explaining the configuration of the developing device 3 provided in each image forming unit 6. In FIG. 2, for the sake of convenience, the position of the developing device 3 facing the photosensitive drum 1 is shown on the side opposite to that shown in FIG. 1, and the alphabets indicating the color divisions are omitted. is there.

In FIG. 2, the developing device 4 uses a configuration in which a two-component developer in which toner and carrier are mixed is used.
In the developing device 4, a developing roller 3 </ b> A corresponding to a plurality of developer carrying members arranged in the direction of gravity in the moving direction of the photosensitive drum 1 in the developing tank 30, that is, two in FIG. 3B, doctor blades 3C and 3C ′, which are provided opposite to the developing rollers 3A and 3B and set the layer thickness corresponding to the developer carrying amount, and the developing rollers 3A and 3B. Developer supplying members 3D and 3D ′ provided respectively.

  The feature of the present embodiment is that the developer supplying parts 3D and 3D 'correspond to members used in the developer collecting part. Details of each member will be described below.

  Each of the developing rollers 3A and 3B includes a fixed magnetic pole in which a plurality of magnetic poles are arranged along the circumferential direction, and a developing sleeve that can rotate around the outer periphery of the fixed magnetic pole. The magnetic brush is moved by raising a magnetic brush of a two-component developer containing

  In this embodiment, the developing rollers 3 </ b> A and 3 </ b> B have a forward rotation and a rotation of the photosensitive drum 1 that have a relationship in which the developing rollers 3 </ b> A and 3 </ b> B are in a direction along the rotational direction of the photosensitive drum 1 at a position facing the photosensitive drum 1. Each of the reverse rotations having a relationship that is opposite to the direction can be selected. In other words, when the photosensitive drum 1 rotates in the clockwise direction, when the developing roller side rotates in the counterclockwise direction, the case where the peripheral surface moves in the same direction at the position where both face each other is forward rotation. On the contrary, the rotation in which the developing roller side moves in a direction opposite to the moving direction of the photosensitive drum 1 at the position facing the photosensitive drum 1 and the developing roller side is the reverse rotation.

  The developer supply members 3D and 3D ′ are configured by a transport screw whose rotation direction is set so that the developer can be transported in a direction opposite to each other. Developers can not go back and forth. In FIG. 2, reference numerals 3D1 and 3D1 ′ denote collection units on which the developer supply units 3D and 3D ′ are arranged. In the following description, the developer supply member indicated by reference numeral 3D is referred to as a first developer supply member, and the developer supply member indicated by reference numeral 3D 'is referred to as a second developer supply member.

  Of the collection units 3D and 3D ′, the collection unit 3D1 ′ in which the second developer supply unit 3D ′ is arranged is connected to the developer storage unit 40 provided in the developer supply mechanism shown in FIG. Has been.

  The developer conveyed to the developer container 40 is supplied with a new toner and subjected to a stirring process for ensuring a predetermined toner concentration and charge amount, and then again passes through an independent conveyance path. Are supplied toward the developer supply members 3D and 3D ′.

The configuration of the developer supply mechanism provided with the developer accommodating portion 40 is shown in FIG.
In FIG. 3, the developer supply mechanism includes a developing tank 30 that stores a developing roller and a developer supplying unit in the developing device 3, and a recovery unit 3D 1 ′ in the developing tank 30 at a position away from the developing tank 30. A developer container 40 that stirs and mixes the developer collected by the second developer supply member 3D ′ and the new toner corresponding to the consumed toner, and replenishes the new toner toward the developer container 40. Toner supply unit 60, rotary feeder 50 for transferring the developer after stirring and mixing discharged from developer storage unit 40, and developer circulation drive source for transferring the developer toward developing tank 30 by air pressure The air pump 51 corresponding to is provided as a main part. In FIG. 3, the developing tank 30 is configured in a cartridge shape.

  The developer tank 30 and the developer container 40 are respectively connected to the developer recovery flow path 41 connected to one end in the axial direction of the second developer supply member 3D ′ in the developer tank 30 and the developer tank 30 in the developer tank 30. The developer supply passages 42 and 42 'are connected to the supply portions 3D1 and 3D1' where the developer supply members 3D and 3D 'are located to form a developer circulation path. It has come to be used as. In FIG. 3, for the sake of convenience, reference numerals 3 </ b> A, 3 </ b> B, 3 </ b> D, and 3 </ b> D ′ are attached to the rotation shaft of the developing roller and the rotation shaft of the developer supply member, respectively, to indicate the positions of the members.

  The developer supply passages 42 and 42 'connected to the developing tank 30 are connected to one side in the axial direction of each developer supply member 3D and 3D' in the developing tank 30, or as shown in FIG. Further, the developer supply members 3D and 3D ′ are supplied on the one side (the position indicated by reference numeral 42A in FIG. 7) and the other side (the position indicated by reference numeral 42A ′ in FIG. 7) in the axial direction of the developer supply members 3D and 3D ′. The cases where the members 3D and 3D ′ are connected to different positions in the longitudinal direction (axial direction) can be selected.

  In the case of the connection method shown in FIG. 7, as shown in FIG. 8, the photosensitive member is taken into consideration that the developer deposition position in the developer feeding direction in the developer supply members 3D and 3D ′ is biased. The supply state of the developer to the drum 1 is balanced in the axial direction.

  In the connection method shown in FIG. 7, the conveyance mode by this will be described later, but the developer supply paths 42, 42 ′ are connected to different positions in the longitudinal direction (axial direction) of the developer supply members 3 D, 3 D ′. Therefore, as shown in FIG. 8, the amount of developer deposited on the downstream side in the transport direction of the developer transported in the longitudinal direction between the developing rollers can be compensated for each other. Thereby, the supply amount of the developer in the longitudinal direction of the developing roller when the developing roller for the photosensitive drum 1 is combined is balanced. As a result, as indicated by the wavy line in FIG. 5, even if the supply amount of one developing roller is low in a part of the longitudinal direction of the developing rollers 3A and 3B, the supply amount of the other developing roller is large. This makes it possible to balance the supply amount and prevent unevenness in the toner density.

  On the other hand, in FIG. 3, the developer accommodating portion 40 has an appearance like a silo having an upper part in a cylindrical shape and a lower part in a downward conical shape, and the inside is agitated as described in the features of this embodiment. A member is provided. A driving motor 40 </ b> A that forms a driving unit for the stirring member is provided on the upper portion of the developer accommodating unit 40.

As shown in FIG. 17, the drive motor 40A can be provided with a torque sensor 40B that detects the rotational torque of the stirring member.
In FIGS. 3 and 7, symbol RG indicates a reduction gear.
When the torque sensor 40B is used, the deterioration of the developer is determined by detecting the load state on the stirring member by the torque sensor 40B. That is, since the deterioration of the developer causes a change in the fluidity, the deterioration state of the developer is determined using the fact that this change appears in the change of the shaft torque of the drive motor. In determining the deterioration, the number of revolutions is used in which the change in fluidity easily occurs in response to the volume of the developer and the environment.

  The developer agitated and mixed in the developer container 40 is fed to a rotary feeder 50 that is provided with a paddle that can adjust the supply amount and is driven to rotate by a drive motor 50A, and the supply amount is adjusted at this position. The developer is conveyed toward the developing tank 30 by an air flow generated by the air pump 51 from a plurality of developer outlets.

  The toner supply unit 60 includes a toner tank 61, a toner supply path 62 connected between the toner tank 61 and the developer container 40, and a conveying member such as a screw auger disposed in the toner supply path 62. And a drive motor 63 for driving (not shown).

The operation of the toner supply unit 60 is controlled according to the detection result of a toner concentration detection unit (not shown) provided at the most downstream in the developer transport direction of the developer supply member located in the recovery unit in the developing tank 30. Thus, when it is detected that the toner density is lower than the predetermined density, new toner is replenished from the toner tank 61.
As described above, the replenishment of the toner is performed via the conveying member disposed in the toner supply path 62.

FIG. 4 is a diagram showing an internal configuration of the developer accommodating portion 40 intended for the case where the gear group shown in FIG. 3 is used.
In FIG. 4, the developer container 40 uses a container 43 having a cylindrical shape at the top and a funnel-like shape with a vertical cross-section of a downward cone, and is located at the bottom and has the smallest diameter outlet. 400 communicates with the rotary feeder 50.

  In the internal space of the developer accommodating portion 40, a screw 44A integrated with a rotating shaft 44 hanging from the motor 40A as a stirring member and an output gear of the reduction gear group GR driven by the rotating shaft 44 are linked. A plurality of stirring blades 45 </ b> A constituting a rotatable stirring paddle are provided by being arranged along the circumferential direction of the possible end plate 45 and being integrated with the end plate 45.

  The rotation from the motor 40A is transmitted to the screw 44A that is linked to the rotary shaft 44, and is also transmitted to the end plate 45 via the reduction gear group RG that can be linked to the rotary shaft 44. It is designed to rotate at high speed.

  In this embodiment, the screw 44A is set in a lead direction that moves the developer in the direction opposite to the flow-down direction, and the stirring blade 45A rotates in a direction that suppresses the flow-down by moving across the flow-down developer. To do.

  The rotary feeder 50 connected to the discharge port 400 located at the bottom of the container 43 is provided to control the developer discharge amount in accordance with the rotation amount of the motor 50A (see FIG. 2). A rotary valve member 50B having a plurality of blades 50B1 that are fixed to the rotation shaft of 50A and extend radially is provided. The rotary valve member 50B introduces a developer corresponding to the amount of rotation into the developer supply channels 42 and 42 ′, and air-conveys the developer toward the developing tank 30 by the air flow generated by the air pump 51. It has become.

  In this embodiment, since a plurality (42, 42 ′) of developer supply channels are provided, the developer supply channels separated from each developer supply unit 3D1.3D1 ′ (see FIG. 2). A configuration capable of distributing the developer from the developer accommodating portion 40 is used for each of 42 and 42 ′.

  Although the details of the distribution of the developer to the developer supply channels 42 and 42 ′ are not shown, the inside of the rotary feeder 50 is divided, and a rotary valve member is provided in the divided space so as to be independently rotatable. A configuration is used in which the developer outlet communicating with the divided space of the branch box 52 connected to the lower portion of the rotary feeder 50 is connected to the developer supply channels 42 and 42 ′.

  By rotating selected rotary valve members including both in the rotary feeder 50, the developer from the developer container 40 is introduced into either or both of the branch boxes 52 positioned below, respectively, and the developer is supplied. The developer whose toner density is optimized is air-conveyed toward the developing tank 30 through one or both of the flow paths 42 and 42 '.

  In the above configuration, since the developer supply channels 42 and 42 'are provided separately, the diameter of the tube including the case where a member made of the channel, for example, a tube made of a flexible material such as silicon is used. Can be made thinner. As a result, the load on the air pump 51 used for conveying the developer airflow can be reduced.

The characteristics of the present embodiment will be described for the above configuration.
As described above, the present embodiment is characterized in that the developer supply members 3D and 3D ′, which are existing parts, are used as the configuration of the collection units 3D1 and 3D1 ′.

  In FIG. 2, as described above, the developing rollers 3 </ b> A and 3 </ b> B are respectively selected to rotate in the forward direction and in the reverse direction with respect to the moving direction of the photosensitive drum 1, that is, the rotating direction. .

  5 and 6 are diagrams showing a state of transport of the developer in the developing layer 30, and FIG. 5 shows the development roller 3A, the first developer supply member 3D, and the second supply member 3D ′. FIG. 6 shows the flow of the developer between the developing roller 3B and the second developer supply member 3D ′.

  The developer is transferred to the developing rollers 3A and 3B toward the developing rollers 3A and 3B while the developer is conveyed along the axial direction by the rotation of the first and second developer supply members 3D and 3D ′. .

  On the other hand, in the developing roller 3A, the developer remaining on the developing roller 3A after the development is scattered from the circumferential surface of the roller by the repulsive magnetic field installed inside the roller, and as shown in the dashed line in FIG. 2 and FIG. It moves toward the second developer supply member 3D ′.

  In the second developer supply member 3D ′, development in which the toner concentration and the charge amount are adjusted from the developer container 40 via the developer supply flow path 42 ′ in addition to the developer moved from the developing roller 3A. An agent will be introduced. For this reason, in the second developer supply member 3D ′, the amount of developer circulating from the developer supply unit 40 can be reduced by using the developer that moves directly from the developing roller 3A. It becomes possible.

  In terms of reducing the amount of developer circulation, the developer collected after development is moved directly to the developer container and stirred and mixed to adjust the toner concentration and charge amount. As the supply amount, it is necessary to set the supply amount to the developing roller per unit time (pumping amount per unit area × developing linear velocity × pumping width) or more. However, in this embodiment, there is an advantage that the supply amount of the developer can be reduced by using the developer collected in the developing unit as it is in the developing unit as compared with the case where the developer is supplied again from the developer containing unit. is there.

  In addition, since the developer supply members 3D and 3D 'are used as the collection unit, it is not necessary to provide the collection unit. Therefore, it is possible to prevent the apparatus from being enlarged as in the case where the collection unit is provided. In particular, since the second developer supply member 3D ′ also functions as a developer supply conveying screw for the developing roller 3B, the delivery of the developer is improved by shortening the distance to the developing roller 3B. At the same time, the developer roller 3A is also approached, so that the recovery of the developer from the developer roller 3A can be facilitated.

Next, a partial modification of the configuration shown in FIG. 3 will be described.
As described above, FIG. 7 shows a connecting method of the developer supply flow paths 42 and 42 ′ connected to the developing tank 30 on one side in the axial direction between the developer supply members 3D and 3D ′ (in FIG. , The position indicated by reference numeral 42A) and the other side (position indicated by reference numeral 42A 'in FIG. 7), respectively, connected to different positions in the longitudinal direction (axial direction) of the developer supply members 3D and 3D'. Is shown.

  The relative position in the axial direction of the recovery unit using the first developer supply member 3D and the recovery unit using the second developer supply member 3D 'communicates with the recovery flow path 41. In the configuration shown in FIG. 7, a recovery path 41A and a recovery transport path 41B with a built-in screw for transporting the developer recovered toward the recovery flow path 41 are provided in the recovery section where the first developer supply member 3D is located. To the recovery passageway 41.

  In the configuration shown in FIG. 7, the first developer supply member 3 </ b> D and the second developer supply member 3 </ b> D and the second developer supply member 3 </ b> D and 3 </ b> D ′ are utilized by utilizing the fact that the positions of the developer supply portions are different in the axial direction. The conveyance direction with respect to the developer supply member 3D ′ is set in the reverse direction. As a result, as described with reference to FIG. 8, the density distributions in the axial direction of the developer supply members 3D and 3D 'are balanced.

  FIG. 9 is a schematic diagram for explaining the developer conveyance path shown in FIG. 7, and the developer conveyance directions by the first and second developer supply members 3D and 3D ′ are reversed. .

  As shown in FIG. 9, the recovery units in which the first and second developer supply members 3 </ b> D and 3 </ b> D ′ are respectively arranged supply the developer from the developer storage unit 40 and the developer storage unit 40. In this configuration, the developer is separately conveyed toward the surface.

As a result, as shown in FIGS. 10 and 11, the developer flows into the first and second developer supply members 3D and 3D ′. Collected and again supplied separately to the developing rollers 3A and 3B. As a result, the developer is re-pumped in each recovery unit.
FIG. 12 is a diagram illustrating characteristics of an example according to the embodiment of the present invention . The characteristic of this example is that a plurality of developer accommodating portions corresponding to a developer agitation and mixing portion are provided, and each developer accommodating portion is provided. There is a feature in connection with the recovery part.

In FIG. 12, two sets of developer accommodating portions 40 having the configuration described in FIGS. 3 and 4 are provided corresponding to the number of recovery portions.
The connection between each developer storage unit and the collection unit is as follows.
Developer is supplied from one developer storage unit 40 to the supply unit in the recovery unit where the first developer supply member 3D is disposed, and the recovery unit supplies the developer to the second developer storage unit 4000. The developer is conveyed toward the end. Then, the developer from the second developer storage unit 4000 is supplied to the supply unit in the recovery unit in which the second developer supply unit 3D ′ is disposed, and the first development is performed from the recovery unit. The developer is conveyed toward the agent container 40.

  In other words, as a configuration for transporting the developer to the developer accommodating portion 40, 4000 where the developer is agitated and mixed, the developer accommodating portion 40 corresponding to the first agitating portion is replaced with the first developer supply member 3D. The recovery channel 3D1 is connected to the supply channel 42 corresponding to the first supply conveyance path, and the developer storage unit 4000 corresponding to the second stirring unit is recovered with the second developer supply member 3D ′. The developer is collected from the supply channel 420 corresponding to the second supply conveyance path connected to the unit 3D ′ and the recovery unit 3D including the first developer supply member toward the second developer storage unit 4000. The developer is recovered from the recovery channel 41 corresponding to the first recovery transport path and the recovery unit 3D1 ′ having the second developer supply member 3D ′ toward the first developer accommodating unit 40. And a recovery channel 410 corresponding to two recovery transport paths. To have.

  As for the movement of the developer in the developing unit 30, the developer from the first developer accommodating unit 40 is in the first supply conveyance path with respect to the collecting unit including the first developer supplying unit 3D. When it moves through the supply flow path 42, it is supplied to the developing roller 3A through the developer supply member 3D. After the development, the developer from the developing roller 3 </ b> A moves to the second developer accommodating unit 4000 via the recovery channel 410 corresponding to the second recovery transport path.

  On the other hand, with respect to the second developer supply member 3D ′, the developer moves from the second developer accommodating portion 4000 through the supply flow path 420 corresponding to the second supply conveyance path, and the second developer. The toner is introduced into a collecting unit having a supply member 3D ′ and supplied to the developing roller 3B via the second developer supply member 3D ′. After development, the developer moves from the developing roller 3 </ b> B to the first developer accommodating portion 40 through a recovery channel 41 corresponding to the first recovery transport path.

  In such a configuration, the toner density and the charged state are adjusted by receiving toner replenishment from the first and second developer accommodating portions 40 and 4000 in the course of the developer being conveyed into the developing portion 30. become. For this reason, the developer is supplied in a state where the toner density is stable by following the above-described transport path.

  By the way, in the above-described embodiment, it is assumed that the developer agitation and mixing including toner replenishment is performed in both of the developer accommodating portions 40 and 4000. It is also possible to have functions other than replenishment.

  FIG. 13 is a diagram for the second developer accommodating portion 4000. In FIG. 13, instead of the stirring blade 45A provided in the container 43 of the second developer accommodating portion 4000, a mesh-like shape is used. A rotating blade 450A is provided.

  The rotating blade 450A has a function of breaking the aggregated developer when the developer in the container 43 is aggregated.

  Aggregation of the developer not only deteriorates the fluidity, but in the layer thickness regulation executed before reaching the developing roller, the developer that is agglomerated accumulates in the layer thickness regulation position, thereby causing the developer to be uniform. This causes a problem that the supply is not performed. Therefore, the above-mentioned problems can be solved by breaking the aggregation of the developer by rotating the rotary blade 45A at a high speed.

  Further, one of the developer accommodating portions can be used for detecting the deterioration state of the developer. In this case, the configuration shown in FIG. 17 can be used.

  Since it is possible to determine the deterioration of the developer in the developer container 4000, it is possible to easily determine the replacement time of the developer circulating in the developing device. In particular, in the developer container 4000 having such a function, the toner is not replenished in order to have the above-described function, so that the fluidity of the developer in the container 43 is stable. Therefore, accurate index detection can be performed.

Next, a modification of the main part of the embodiment shown in FIG. 2 will be described.
The configuration shown in FIGS. 14 to 16 is characterized in that the developer is merely circulated in each recovery unit, and the developer storage unit that is a developer supply unit from the outside is not provided.

  In FIG. 14, the difference from the configuration shown in FIG. 1 is that a recovery unit 3D1, 3D1 ′ including the first developer supply agent 3D and the second developer supply agent 3D ′ includes a recovery unit. The conveyance part 500 provided adjacent to the is communicated.

  The communication position between the transport unit 500 and each recovery unit is based on the transport direction of the developer by the transport screw used for the developer supply unit located in each recovery unit, and the first developer supply member 3D The collecting unit located is positioned on the upstream side in the developer transport direction, and the collecting unit located on the second developer supply member 3D ′ is positioned on the downstream side in the developer transport direction. In FIG. 14, reference numeral 500A denotes a communication position in the collection unit where the first developer supply member 3D is located, and reference numeral 500B denotes a communication position in the collection unit where the second developer supply member 3D ′ is located. Show.

  Inside the conveyance unit 500, the first conveyance member 501 that transfers the developer to and from the second developer supply member 3D ′, and the communication position on the collection unit side described above are provided. A second conveying member 502 is provided that uses a conveying screw arranged with its axis inclined so that the end in the axial direction is located.

  FIG. 15 is a diagram showing a developer conveyance mode for the first and second developer supply members 3D and 3D ′ and the second conveyance member 502. As shown in FIG. After being moved from the developing roller 3A to the second developer supply member 3D ′ and introduced into the transfer chamber 500 through the communication portion, the second transfer member 502 causes the first developer supply member 3D to move to the second developer supply member 3D ′. Move again toward.

  On the other hand, FIG. 16 is a diagram showing a developer conveyance form between the second developer supply member 3D ′ and the first conveyance member. As shown in the figure, the developer is transferred between the two members via the communication position.

  In the above configuration, the configuration for toner replenishment and stirring and mixing can be omitted, so that the development configuration can be reduced in size. In addition to the development roller and the developer supply member, the development unit uses only the above-described development roller and developer supply member by providing a transport unit in addition to the development roller and the developer supply member. It becomes larger in size than the case. However, in this configuration, the second developer supply unit has two types of developer, that is, the developer generated after development from the developing roller facing the first developer supply member and the developer from the second developer supply member. Will be supplied. For this reason, unlike the conventional one, the density of the second developer supply member is increased, and the density change can be reduced. In the configurations shown in 14 to 16, the first and second transport members 5012 and 502 can have different rotational speeds, and the transport amount can be adjusted between the two members. it can.

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 3 Developing apparatus 3A 1st developing roller 3B 2nd developing roller 3C Doctor blade 3D, 3D 'Developer supply member 3D1, 3D1 Recovery part 30 Developer tank 42, 42' Developer supply flow path 100 Image forming apparatus

JP 2008-256901 A JP 2006-251585 A JP 2009-014992 A

Claims (5)

A developing device including a developer carrier for supplying a developer to an electrostatic latent image formed on an image carrier,
A plurality of the developer carriers are provided in the direction of gravity along the moving direction of the image carrier, and each includes a developer supply unit and a developer carrying amount regulating member,
A collection unit is provided at a position where developers from the plurality of developer carriers are collected,
Wherein the recovery unit, the developer supply unit is used et is a configuration in which the developer is agitated and mixed via the recovery unit is pneumatic conveying independently for each developer supplying unit is provided A developing device. The developing device according to claim 1,
The means for agitating and mixing the developer includes a plurality of agitation units connected to each developer supply unit that constitutes the recovery unit, and the agitation unit contains the developer recovered from the recovery unit. A configuration for supplying toner according to a result of detecting the toner density and a configuration for stirring and mixing the supplied toner and the developer are provided, and the developer that has been stirred and mixed is conveyed toward the developer supply unit. developing apparatus is characterized in that. The developing device according to claim 2 , wherein
A first agitation unit corresponding to one of the agitation units is a first agitation corresponding to one of the developer supply units as a configuration for conveying the agitated and mixed developer to each of the developer supply units. A first supply conveyance path for connecting to the developer supply unit, and a second developer corresponding to the other one of the developer supply unit and a second stirring unit corresponding to the other one of the stirring unit A second supply transport path for connecting to the supply section; a first recovery transport path for connecting a recovery position of the second developer supply section to the first stirring section; and the first And a second collection conveyance path for connecting the collection position of the developer supply section to the second stirring section . The developing device according to claim 3.
The second stirring unit connected to the collection position of the first developer supply unit via the second transport path detects deterioration of the developer collected from the first developer supply unit. A developing device characterized in that means for carrying out the processing is provided . An image forming apparatus using the developing device according to claim 1 .

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