JP3846190B2 - Development device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to electrophotographic image formation such as a printer, a copying machine, and a facsimile apparatus that visualizes an electrostatic latent image formed on an image carrier such as a photosensitive drum or a photosensitive belt by attaching toner. The present invention relates to a developing device used in the apparatus.
[0002]
[Prior art]
As this type of developing device, there is a one-component developing type device using a one-component toner. For example, in JP-A-7-44011, a thin layer of nonmagnetic toner is formed on the surface of a developing roller (developing sleeve), and this is brought into contact with the surface of a photosensitive drum as an image carrier at a predetermined developing position. Describes an apparatus for developing. More specifically, the developing roller is elastically contacted with the photosensitive drum and with a nip width by deformation, and rotates in a direction opposite to the rotation direction of the photosensitive drum to face the image carrier. The toner is transported to the developing position. A supply roller (toner supply body) is provided on the opposite side of the development position across the developing roller, and nonmagnetic one-component toner stored in a toner storage section provided in the developing device main body is supplied. Supply to the developing roller. In addition, a regulating blade is disposed below the developing roller so that the tip of the developing roller comes into contact with the developing roller, and the amount of toner transported to the developing position by the developing roller is regulated, and the surface of the developing roller is A thin layer of toner is formed. The toner thus formed is conveyed to a development position and develops a latent image on the photosensitive drum.
[0003]
[Problems to be solved by the invention]
By the way, in the developing device configured as described above, the non-magnetic one-component toner may be deteriorated by long-term use. For example, the toner on the developing roller may be rubbed with a supply roller or a regulation blade, causing the toner to break. In addition, the toner and the external additive are rubbed at the contact position, thereby causing problems such as embedding of the external additive in the toner base particles and the external additive being detached from the toner. . Further, such deteriorated toner may cause a so-called filming phenomenon in which the toner remains and adheres to the surface of the developing roller or the regulation blade. Due to such factors, density unevenness may occur or an image with low graininess may be formed, leading to image defects.
[0004]
Here, in order to suppress the influence of the deteriorated toner, returning the deteriorated toner to the toner storage unit and mixing it with the fresh toner stored in the toner storage unit is one effective measure. However, in the conventional apparatus, it cannot be said that the recovery efficiency of the deteriorated toner in the toner storage unit is high. Further, in the conventional apparatus, a relatively wide space is formed at a contact position where the regulating blade and the developing roller contact each other, and the deteriorated toner may stay in this space in a compacted state. For this reason, the recovery of the deteriorated toner to the toner reservoir does not proceed, and it is difficult to improve the image defect caused by the deteriorated toner.
[0005]
The present invention has been made in view of the above problems, and improves the recovery efficiency of the deteriorated toner in the toner storage portion in which the fresh toner is stored, suppresses image defects due to the deteriorated toner, and increases the latent image on the image carrier. An object of the present invention is to provide a developing device capable of developing toner with high quality and stability.
[0006]
[Means for Solving the Problems]
The present invention provides a plurality of developing devices for developing a latent image formed on an image carrier with toner, and a developer holding device that is rotatably provided and holds the plurality of developing devices arranged in the rotational direction. A developing device holding means, and rotationally positioning the developing device holding means so that one of the developing devices is selectively placed opposite to the image carrier and toner development of the latent image by the developing device is performed. Each of the developing devices includes a toner storage unit that stores toner, a toner carrier that conveys toner to a development position facing the image carrier by rotating while carrying the toner, and a toner carrier A toner supply body for supplying toner in the toner reservoir to the toner carrier by rotating while contacting the toner carrier on the upstream side of the developing position in the rotation direction of the toner, a toner carrier and the toner A regulating means for regulating a surplus toner at a contact position between the contact position between the supply body and the developing position and a developing position to form a charged toner thin layer on the surface of the toner carrier; A communication path is formed from the post-regulation space facing the carrier, the toner supply body, and the regulation means to the toner storage unit, and the post-regulation space and the toner storage unit are communicated with each other. A toner flow control means for allowing toner flow from the rear space to the toner storage section, and for regulating toner flow from the toner storage section to the post-regulation space;
The toner storage section, the toner supply body, and the communication means are arranged in the order of the toner storage section, the toner supply body, and the communication means in the gravity direction from the top in a state where the toner support body is disposed opposite to the image carrier. The toner flow control means includes a valve member whose one end is swingably supported with respect to the communication means, and whose other end is capable of coming into contact with the outer peripheral surface of the toner supply body. The valve member has a toner carrier that is disposed opposite to the image carrier, and the other end of the valve member abuts against the toner supply member due to its own weight, and the toner from the toner reservoir to the post-regulation space. While the flow is restricted, the toner reservoir, the toner supply body, and the communication means are arranged in reverse order from the top in the direction of gravity in the gravity direction away from the position where the toner carrier is opposed to the image carrier. The other end is It is characterized by being configured to allow toner fluidity to the toner reservoir from apart from regulations after space from over donor.
[0007]
In the developing device configured as described above, the regulated space facing the toner carrier, the toner supply body, and the regulating means is communicated with the toner storage portion through the communication path. In addition, toner flow control means is provided on the communication path, and allows toner flow from the post-regulation space to the toner storage portion, while restricting toner flow from the toner storage portion to the post-regulation space. . For this reason, the flow of fresh toner from the toner reservoir to the regulated space is restricted while one developing device is selectively placed opposite the image carrier and toner development of the latent image by the developing device is performed. The post-regulation space is empty at the start of development by the developing device. As the development process proceeds, fresh toner does not flow from the toner reservoir, and only the toner generated at the contact position or the contact position by the development process, that is, the deteriorated toner, is captured in the post-regulation space. To go. Then, when the developing process by the developing unit is completed and each developing unit rotates, the deteriorated toner trapped in the post-restriction space with the rotation operation flows out from the post-restriction space to the toner reservoir through the toner flow control means. As a result, the regulated space returns to the empty state again. As described above, the deteriorated toner is captured by the post-regulation space, the development processing is completed, and the deteriorated toner is collected in the toner storage unit during the toner development by another developing device.
[0008]
Further, the developing device according to the present invention is configured such that one end of the toner flow control unit is swingably supported with respect to the communication unit, and the other end can contact the outer peripheral surface of the toner supply body. The valve member is configured. The valve member is desirably arranged as follows according to the rotation direction of the toner supply body in order to effectively prevent the toner from flowing into the post-regulation space from the toner reservoir.
[0009]
First, when the toner supply body rotates in a direction opposite to the rotation direction of the toner carrier, the valve member is arranged such that one end thereof is positioned upstream of the other end in the rotation direction of the toner supply body. It is desirable to arrange in. On the other hand, when the toner supply body rotates in the same direction as the rotation direction of the toner carrier, the valve member is arranged so that one end thereof is positioned downstream of the other end in the rotation direction of the toner supply body. It is desirable to arrange.
[0010]
Further, when the restricting means is disposed below the contact position in the vertical direction, one end of the valve member can swing relative to the communicating means below the virtual horizontal line passing through the rotation center of the toner supply body. In this case, the area of the peripheral surface of the toner supply body that slides on the fresh toner in the toner reservoir increases. Thus, the increase in the rubbing area increases the amount of preliminary charge given to the toner before reaching the contact position, so that the toner can be charged more reliably.
[0011]
Further, the restricting means is configured such that the rear end portion thereof is fixed below the contact position in the vertical direction, and the front end portion thereof elastically contacts the surface of the toner carrier at the contact position. In addition, it is desirable that the front end portion is disposed upstream of the rear end portion in the rotation direction of the toner carrier. In this case, the regulating means comes into contact with the peripheral surface of the toner carrier at an obtuse angle, and the toner scraped from the toner carrier by the regulating means, that is, deteriorated toner can be guided to the post-regulation space. Toner recovery efficiency can be improved.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a view showing an image forming apparatus equipped with an embodiment of a developing device according to the present invention. In this image forming apparatus, a photoconductor 2 is provided in the apparatus main body 1 so as to be rotatable in the arrow direction D1 in FIG. Further, a charger 3 as a charging unit, a rotary developing unit 4 as a developing unit, and a cleaning unit 5 are arranged around the photosensitive member 2 along the rotation direction D1. The charger 3 is applied with a charging bias from a charging bias circuit (not shown), and uniformly charges the outer peripheral surface of the photoreceptor 2.
[0013]
Then, laser light L is irradiated from the exposure unit 6 toward the outer peripheral surface of the photosensitive member 2 charged by the charger 3. The exposure unit 6 scans and exposes the photosensitive member 2 with a laser beam L in accordance with image data obtained by developing the image formation command and develops an electrostatic latent image corresponding to the image formation command on the photosensitive member 2. Form.
[0014]
The electrostatic latent image thus formed is developed with toner by the developing unit 4. That is, in this embodiment, as the developing unit 4, a yellow developing unit 4Y, a cyan developing unit 4C, a magenta developing unit 4M, and a black developing unit 4K are provided to be rotatable about an axis. . These developing units 4Y, 4C, 4M, and 4K are rotationally positioned and selectively abut against the photoreceptor 2 to apply toner to the surface of the photoreceptor 2. As a result, the electrostatic latent image on the photoreceptor 2 is visualized with the selected toner color. The configuration and operation of the developing unit 4 will be described in detail later.
[0015]
The toner image developed by the developing unit 4 as described above is primarily transferred onto the intermediate transfer belt 71 of the transfer unit 7 in the primary transfer region TR1. A cleaning unit 5 is disposed at a position advanced in the circumferential direction (rotation direction D1 in FIG. 1) from the primary transfer region TR1, and toner remaining on the outer peripheral surface of the photoreceptor 2 after the primary transfer is disposed. Scratch off.
[0016]
The transfer unit 7 includes an intermediate transfer belt 71 spanned by a plurality of rollers, and a drive unit (not shown) that rotationally drives the intermediate transfer belt 71. When a color image is transferred to the sheet member S, each color toner image formed on the photosensitive member 2 is superimposed on the intermediate transfer belt 71 to form a color image, and a predetermined secondary transfer region. In TR2, the color image is secondarily transferred onto the sheet member S taken out from the cassette 8. The sheet member S on which the color image is formed in this way is conveyed to the discharge tray portion 11 provided on the upper surface portion of the apparatus main body 1 via the fixing unit 9.
[0017]
Next, the configuration and operation of the rotary developing unit 4 provided in the image forming apparatus of FIG. 1 will be described in detail. FIG. 2 is a view showing a rotary developing unit as an embodiment of the developing device according to the present invention. FIG. 3 is a partially enlarged view of the developing device of FIG. As shown in FIG. 2, the rotary developing unit 4 has a rotating shaft 4a at its center and a support frame 4b fixed to the rotating shaft 4a. The four color developing devices 4Y and 4C described above are used. , 4M, 4K are fixed radially to the support frame 4b around the rotation shaft 4a by fixing brackets (not shown). Further, a drive unit (not shown) is connected to the rotary shaft 4a via a clutch. By driving the drive unit, the support frame 4b is rotated, and the four developing devices 4Y, 4C, 4M, and 4K are rotated. One developing device can be selectively positioned at a developing position DP (FIG. 3) opposed to the photosensitive member 2. Thus, in this embodiment, the support frame 4b corresponds to the “developer holding unit” of the present invention.
[0018]
The developing devices 4Y, 4C, 4M, and 4K held by the support frame 4b have the same configuration. Therefore, here, the configuration of the developing device 4Y will be described in detail, and the other developing devices 4C, 4M, and 4K will be denoted by the same reference numerals, and description of the configuration will be omitted.
[0019]
In the developing device 4Y, a housing 43 serving as a main body of the developing device is formed by integrally combining the two housing members 41 and. Inside the housing 43, the toner storage portion 45 and the toner storage portion 45 are partitioned by a partition wall 411 protruding from a substantially central portion of the housing member 41 toward the housing member 42. The toner storage unit 44 is a space for storing yellow toner in advance, while the toner storage unit 45 receives toner T corresponding to the amount used during toner development from the toner storage unit 44, and during toner development processing, This is a space for storing toner to be used for development. Therefore, in this embodiment, the toner storage unit 44 is set to be relatively larger than the toner storage unit 45.
[0020]
A supply roller 46 is disposed in the toner storage unit 45 and rotates in the direction of the developing roller 47 while contacting the developing roller 47 that is driven to rotate at the foremost side of the housing 43. That is, in this embodiment, the developing roller 47 rotates in the direction D2 opposite to the rotation direction D1 of the photoconductor 2 while carrying the toner T, and the toner T is placed on the surface of the photoconductor 2 at the development position DP (FIG. 3). It is comprised so that it may adhere. In order to supply the toner T to the developing roller 47, the supply roller 46 comes into contact with the developing roller 47 at a contact position CP (FIG. 3) upstream of the developing position DP in the rotation direction D2 of the developing roller 47. However, the developing roller 47 rotates in the direction D3 opposite to the rotation direction D2. As a result, the yellow toner T is rubbed against the surface of the developing roller 47 to form a toner layer having a predetermined thickness (for example, several tens of μm) on the surface of the developing roller 47. Thus, in this embodiment, the supply roller 46 and the developing roller 47 function as the “toner supply body” and the “toner carrier” of the present invention, respectively.
[0021]
Further, a regulation blade 48 corresponding to the “regulation means” of the present invention is disposed at the contact position EP (FIG. 3) sandwiched between the contact position CP and the development position DP. The regulation blade 48 includes a plate-like member 481 such as stainless steel or copper, and an elastic member 482 such as a rubber or resin member attached to the tip of the plate-like member 481. The rear end portion of the plate member 481 is fixed to the housing member 41 in a so-called counter state. That is, in the rotation direction D 2 of the developing roller 47, the elastic member 482 attached to the front end portion of the plate-like member 481 is disposed upstream of the rear end portion of the plate-like member 481. The elastic member 482 is in elastic contact with the surface of the developing roller 47 at the contact position EP. Therefore, the thickness of the toner layer formed on the surface of the developing roller 47 is finally restricted to about 10 μm by the restriction blade 48. At this time, the toner is charged to a predetermined polarity by friction with the regulating blade 48. In this way, the toner T charged to a predetermined polarity with respect to the developing roller 47 is supplied to the developing position DP, and the electrostatic latent image on the photoreceptor 2 can be developed with the toner T on the developing roller 47. On the other hand, surplus toner scraped from the developing roller 47 by the regulating blade 48, that is, the deteriorated toner DT, is scattered in the regulated space SP facing the supply roller 46, the developing roller 47, and the regulating blade 48.
[0022]
As shown in FIG. 3, the post-regulation space SP is communicated with the toner storage unit 45 by a communication path R sandwiched between the bottom 412 and the partition 411 of the housing member 41 and the supply roller 46. For this reason, during the developing process by the developing device 4Y, the deteriorated toner DT scattered in the post-regulation space SP is accumulated on the bottom 412 of the housing member 41. Thus, in this embodiment, the bottom part 412 and the partition 411 of the housing member 41 function as the “communication means” of the present invention.
[0023]
On the communication path R, a valve member 49 made of a resin film such as polyethylene terephthalate (PET) or polypropylene (PP) is disposed in a trail state as the “toner flow control means” of the present invention. That is, the valve member 49 has one end 49a attached to the partition wall 411 with a hinge structure so as to be swingable with respect to the partition wall 411, while the other end 49b is in contact with the outer peripheral surface of the supply roller 46. It is provided as possible. Further, in this embodiment, one of the valve members 49 in the rotation direction D3 of the supply roller 46 corresponds to the rotation of the supply roller 46 in the direction D3 opposite to the rotation direction D2 of the developing roller 47, that is, the so-called width rotation. The end (swinging support shaft portion) 49 a is disposed so as to be located upstream of the other end (tip portion) 49 b of the valve member 49. For this reason, as described below, the other end 49b moves away from and contacts the supply roller 46 by its own weight according to the rotation position of the developing device, and the toner from the toner storage portion 45 to the post-regulation space SP is brought about by contact. While preventing the flow, the toner can flow from the post-regulation space SP to the toner reservoir 45 by separation.
[0024]
Here, the operation of the rotary developing unit 4 configured as described above will be described focusing on the operation of the yellow developing device 4Y. In this embodiment, while forming toner images in the order of yellow (Y), cyan (C), magenta (M), and black (K), each toner image is superimposed on the intermediate transfer belt 71 to form a color image. To do. Therefore, first, the yellow developing device 4Y is selectively positioned at the developing position DP (FIG. 3) facing the photosensitive member 2. In this state, the valve member 49 falls to the supply roller 46 side by its own weight, and the other end 49 b is in contact with the peripheral surface of the supply roller 46. Therefore, while the toner development by the developing device 4Y is being performed, the flow of fresh toner from the toner storage portion 45 to the post-regulation space SP is prevented, and the post-regulation space SP is started at the development start time by the development device 4Y. Is empty. As the development process proceeds, only the toner generated at the contact position CP or the contact position EP during the development process, that is, the deteriorated toner DT, is restricted while the toner inflow from the toner reservoir 45 is blocked. It is captured by the rear space SP.
[0025]
When the developing process by the developing device 4Y is completed, the developing unit 4 rotates the rotating shaft 4a each time the toner color is switched so as to sequentially execute the developing process with cyan toner, the developing process with magenta toner, and the developing process with black toner. As a center, it rotates 90 ° counterclockwise on the paper surface of FIG. 1 or FIG. Thus, in the middle of switching from the yellow developing device 4Y to the cyan developing device 4C, the valve member 49 falls to the side opposite to the supply roller 46 due to its own weight, and the other end 49b is separated from the peripheral surface of the supply roller 46, and this separation operation is performed. In conjunction with this, the toner stored in the toner storage section 45 begins to flow out to the toner storage section 44 side. When the developing unit 4 is rotated by 90 °, the yellow developing device 4Y is moved and positioned to the position of the black developing device 4K in FIG.
[0026]
Further, when the development processing with cyan toner is completed and the switching operation from the cyan developing device 4C to the magenta developing device 4M is started, for example, as shown in FIG. The deteriorated toner DT flows out along the partition wall 411 to the toner storage unit 45 and further to the toner storage unit 44 side. Thus, the deteriorated toner DT is reliably collected from the post-regulation space SP. Then, the toner containing portion 44 is sufficiently mixed with fresh toner, and image defects due to deteriorated toner can be further suppressed. As a result, the latent image on the photoreceptor 2 can be developed with high quality and toner stably.
[0027]
Further, as the developing unit 4 rotates, the yellow developing device 4Y is moved and positioned to the position of the magenta developing device 4M in FIG. In this state, the deteriorated toner is almost completely discharged from the communication path R, and the regulated space SP returns to the empty state again. In this way, during the developing process, the deteriorated toner DT is captured by the communication path R by the post-regulation space SP, the developing process by the yellow developing unit 4Y is completed, and the switching to the other developing units 4C, 4M, 4K is in progress. The deteriorated toner is collected in the toner storage unit 45. The other developing devices 4C, 4M, and 4K operate in exactly the same manner as the yellow developing device 4Y.
[0028]
As described above, according to this embodiment, the deteriorated toner DT generated during the developing process is captured in the post-regulation space SP by disposing the valve member 49 functioning as “toner flow control means” on the communication path R. After the development process is completed, the deteriorated toner DT can be reliably collected in the toner storage unit 45 during the toner development by another developing device. In addition, the deteriorated toner collected in this way is mixed not only with the toner stored in the toner storage unit 45 but also with the toner stored in the toner storage unit 44 while the rotary developing unit 4 is rotating. Therefore, it is possible to effectively suppress deterioration in image quality due to deteriorated toner and to stably develop the latent image on the image carrier with high quality.
[0029]
Further, by providing the valve member 49, it is possible to effectively prevent the toner from flowing from the toner storage portion 45 into the post-regulation space SP during the developing process, and effectively prevent the post-regulation space SP from becoming a dust state. can do.
[0030]
Furthermore, in this embodiment, since the regulating blade 48 is fixed to the housing member 41 in a counter state with respect to the developing roller 47, the regulating blade 48 comes into contact with the peripheral surface of the developing roller 47 at an obtuse angle. The toner scraped from the developing roller 47 by the regulating blade 48, that is, the deteriorated toner DT can be guided to the regulated space, which is advantageous in improving the recovery efficiency of the deteriorated toner DT.
[0031]
The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention. For example, the developing device according to the above embodiment is the rotary developing unit 4 in which the supply roller 46 rotates with respect to the developing roller 47, but in the present invention, the supply roller 46 rotates against the developing roller 47. It can be applied to a rotary developing unit. This will be described with reference to FIG.
[0032]
FIG. 5 is a view showing another embodiment of the developing device according to the present invention. The developing units 4Y, 4C, 4M, and 4K constituting the rotary developing unit are largely different from the previous embodiment in the following two points. First, in this embodiment, the supply roller 46 is configured to rotate in the same direction D4 as the rotation direction D2 of the developing roller 47, that is, so-called against rotation. And in order to respond | correspond to this, the valve member 49 is arrange | positioned in the counter state. In other words, in the rotational direction D4 of the supply roller 46, the one end (swinging shaft portion) 49a of the valve member 49 is disposed on the downstream side of the other end (tip portion) 49b of the valve member 49. Yes. For this reason, as in the previous embodiment, the regulated toner SP generated after the development process is treated with the regulated space SP while regulating the flow of toner from the toner reservoir 45 into the regulated space SP during the development process. And can be deposited on the bottom 412 of the housing member 41. Note that the deteriorated toner DT captured in this manner is collected in the toner storage unit 45 and mixed with fresh toner in exactly the same manner as in the previous embodiment, so that deterioration in image quality due to the deteriorated toner can be effectively prevented. .
[0033]
Further, the valve member 49 may be disposed at any position on the communication path. However, as in the above-described embodiment (FIGS. 3 and 5), the regulating blade 48 is more vertically positioned than the contact position CP. When arranged on the lower side, it is preferable to provide one end (swinging shaft portion) 49 a of the valve member 49 on the lower side of the virtual horizontal line X passing through the rotation center of the supply roller 46. This is because by arranging in this way, the area of the peripheral surface of the supply roller 46 that rubs with the fresh toner in the toner reservoir 45 is increased, and the contact position CP is reached as the rubbed area increases. Thus, the amount of preliminary charge given to the toner adhering to the supply roller 46 increases. As a result, the toner can be more reliably charged.
[0034]
In the above-described embodiment, the valve member 49 swings due to its own weight according to the rotation of the rotary developing unit 4. However, the valve member 49 is forcibly shaken by applying a rotational driving force to one end 49 a of the valve member 49. Needless to say, it may be configured to be driven dynamically.
[0035]
In the above-described embodiment, the regulating blade 48 is arranged in a counter state with respect to the developing roller 47. However, such a configuration itself is not an essential configuration of the present invention, and the regulating blade 48 is disposed with respect to the developing roller 47. The present invention may also be applied to a developing device arranged in a trail state.
[0036]
Further, in the above embodiment, the regulating blade 48 in which the elastic member 482 is attached to the tip of the plate-like member 481 is used as the regulating means, but the developing device adopts a plate-like blade such as stainless steel or copper. Needless to say, the present invention can be applied.
[0037]
【The invention's effect】
As described above, according to the present invention, the regulated space is communicated with the toner storage portion by the communication means, and the toner flow control means is provided on the communication path to prevent the toner flow from the regulated space to the toner storage portion. On the other hand, since toner flow from the toner reservoir to the post-regulation space is regulated, only the deteriorated toner is captured in the post-regulation space while regulating the inflow of toner from the toner reservoir during the development process. After the development processing by the developing unit is completed, the deteriorated toner captured in the post-regulation space with the rotation operation of each developing unit can flow out and be collected from the post-regulation space to the toner storage unit via the toner flow control means. . Therefore, the recovery efficiency of the deteriorated toner is improved, image defects due to the deteriorated toner can be suppressed, and the latent image on the image carrier can be stably developed with high quality.
[Brief description of the drawings]
FIG. 1 is a diagram showing an image forming apparatus equipped with an embodiment of a developing device according to the present invention.
FIG. 2 is a view showing a rotary developing unit as an embodiment of the developing device according to the present invention.
3 is a partially enlarged view of the developing device in FIG. 2;
4 is a view for explaining a recovery operation of deteriorated toner in the developing device of FIG. 2; FIG.
FIG. 5 is a diagram showing another embodiment of the developing device according to the present invention.
FIG. 6 is a view for explaining the position of the valve member.
[Explanation of symbols]
2 ... Photoconductor (image carrier)
4 ... Rotary development unit
4Y, 4C, 4M, 4K ... Developer
4a ... Rotating shaft
4b ... Support frame (developer holding means)
45. Toner reservoir
46: Supply roller (toner supply body)
47. Developing roller (toner carrier)
48 ... Regulating blade (regulating means)
49. Valve member (toner flow control means)
49a ... one end (of the valve member)
49b ... (the other end of the valve member)
411 ... Bulkhead (communication means)
412 ... Bottom (communication means)
481 ... Plate member
482 ... Elastic member
CP ... Contact position
D1 ... Rotation direction (of the image carrier)
D2 ... direction of rotation of toner carrier
D3, D4 ... Direction of rotation of toner supply
DP: Development position
EP: Contact position
R ... Communication route
T ... Toner
X ... Virtual horizon

Claims (5)

A plurality of developing units for developing the latent image formed on the image carrier with toner, and a developer holding unit that is rotatably provided and holds the plurality of developing units arranged in the rotation direction; A developing unit holding and rotating the developing unit holding means so that one of the plurality of developing units is selectively disposed opposite to the image carrier and the latent image is developed by the developing unit. A device,
Each developer is
A toner reservoir for storing toner;
A toner carrier that conveys the toner to a development position facing the image carrier by rotating while carrying the toner; and
A toner supplier for supplying toner in the toner reservoir to the toner carrier by rotating in contact with the toner carrier upstream of the development position in the rotation direction of the toner carrier;
A toner thin layer charged on the surface of the toner carrier by regulating excess toner at a contact position where the toner carrier and the toner supplier are in contact with each other and a contact position sandwiched between the development position Regulatory means to form a
Communication means for forming a communication path from the post-regulation space facing the toner carrier, the toner supply body and the regulation means to the toner storage section, and communicating the post-regulation space and the toner storage section;
A toner flow control unit that is provided on the communication path and enables toner flow from the post-regulation space to the toner storage unit, and controls toner flow from the toner storage unit to the post-regulation space. ,
The toner storage section, the toner supply body, and the communication means are arranged in the order of the toner storage section, the toner supply body, and the communication means from the top in the direction of gravity in a state where the toner carrier is disposed opposite to the image carrier. Configured to line up,
The toner flow control means has a valve member whose one end is swingably supported with respect to the communication means, and whose other end is capable of coming into contact with the outer peripheral surface of the toner supply body. And
The valve member has the other end abutting against the toner supply body due to its own weight, and the toner reservoir from the toner reservoir to the post-regulation space in a state where the toner carrier is disposed opposite the image carrier. The toner carrier is separated from the position facing the image carrier, and the toner reservoir, the toner supplier, and the communication means are arranged in the gravity direction in reverse order from the top. The developing device is configured such that the other end of the valve member is separated from the toner supply member by the dead weight of the valve member so that the toner can flow from the post-regulation space to the toner storage portion. . The toner supplier is rotating in a direction opposite to the direction of rotation of the toner carrier;
2. The developing device according to claim 1, wherein the valve member is arranged such that one end thereof is positioned upstream of the other end in the rotation direction of the toner supply body. The toner supply body rotates in the same direction as the rotation direction of the toner carrier, and
2. The developing device according to claim 1, wherein the valve member is disposed such that one end thereof is positioned downstream of the other end in the rotation direction of the toner supply body. The restricting means is arranged below the contact position in the vertical direction,
4. The developing device according to claim 1, wherein one end of the valve member is supported so as to be swingable with respect to the communication unit on a lower side of an imaginary horizontal line passing through a rotation center of the toner supply body. . The restricting means is configured such that its rear end is fixed below the contact position in the vertical direction, and its front end elastically contacts the surface of the toner carrier at the contact position. And,
5. The developing device according to claim 1, wherein the front end portion is disposed upstream of the rear end portion in the rotation direction of the toner carrier.

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