WO2019088539A1

WO2019088539A1 - Developing device with communicating port opening

Info

Publication number: WO2019088539A1
Application number: PCT/KR2018/012519
Authority: WO
Inventors: Tadao Mori
Original assignee: Hp Printing Korea Co., Ltd.
Priority date: 2017-10-31
Filing date: 2018-10-23
Publication date: 2019-05-09
Also published as: JP2019082607A

Abstract

A developing device for an imaging system includes a housing having an accommodation space and a partition to partition the accommodation space into a first accommodation space and a second accommodation space. The partition includes a first communicating port and a second communicating port to fluidly couple the first accommodation space with the second accommodation space. A first conveyance member located in the first accommodation space conveys developer at least partially contained within the first accommodation space from the second communicating port toward the first communicating port. A second conveyance member located in the second accommodation space to convey developer at least partially contained within the second accommodation space from the first communicating port toward the second communicating port. A communicating port opening changes in area in response to a change in environmental conditions.

Description

DEVELOPING DEVICE WITH COMMUNICATING PORT OPENING

A trickle-type developing device gradually supplies a developer into the developing device and gradually discharges a developer having deteriorated electrification performance to prevent an increase of deteriorated carriers.

A carrier developer including a carrier consecutively replaces a deteriorated developer including toner and a carrier in a developer container while an amount of developer corresponding to the supplied amount is discharged from a developer discharge opening formed in the developer container by opening/closing of a cover, which is driven by a solenoid for discharging.

Fig. 1 is a schematic view illustrating an example image forming apparatus.

Fig. 2 is a schematic view illustrating an example developing device.

Fig. 3 is a cross-sectional front view of a developing device illustrating a first communicating port.

Fig. 4 is a corresponding view of Fig. 3 including an example variable member.

Fig. 5 is a cross-sectional front view of a developing device illustrating a second communicating port.

Fig. 6 is a corresponding view of Fig. 5 including an example variable member.

Fig. 7 is a graph illustrating an example relationship between the number of prints and the weight of developer.

Fig. 8 is a cross-sectional side illustrating another example variable member.

In the following description, with reference to the drawings, the same reference numbers are assigned to the same components or to similar components having the same function, and overlapping description is omitted.

A solenoid for discharging may be provided to open/close the cover of the developer container. Damage or clogging of the solenoid for discharging, such as by adhesion of developer to the cover, may affect the opening/closing operation of the cover.

In addition, a developer may change its bulk density depending on the usage environment. For example, under a usage environment at a low temperature, a developer may increase its bulk. Therefore, the opening/closing operation of the cover may be finely adjusted in response to an increased bulk of the developer. However, the adjustments may affect the ability of a solenoid to perform on-off operations.

In some examples, a developing device may be configured to keep an amount of developer constant regardless of changes of environmental conditions.

The developing device for developing an electrostatic latent image formed on an image carrier may include a housing having an accommodation space for containing a developer.

For example, the developing device may include a housing having a partition for partitioning the accommodation space into a first accommodation space and a second accommodation space. The partition may be formed with a first communicating port and a second communicating port spaced from each other to fluidly couple the first accommodation space with the second accommodation space. In some examples, a first conveyance member is contained in the first accommodation space to convey, while stirring, a developer located within the first accommodation space from the second communicating port toward the first communicating port. Additionally, a second conveyance member is contained in the second accommodation space to convey, while stirring, a developer located within the second accommodation space from the first communicating port toward the second communicating port. In some examples, at least one of the first and second communicating ports is provided with a variable member for changing an opening area of the communicating port in response to a predetermined change in environmental conditions.

In some examples, the developer located within the first accommodation space is conveyed by the first conveyance member from the second communicating port toward the first communicating port, and the developer is passed through the first communicating port to the second accommodation space. Additionally, the developer within the second accommodation space is conveyed by the second conveyance member from the first communicating port toward the second communicating port, and develop is passed through the second communicating port to the first accommodation space. At least one of the first and second communicating ports may be provided with a variable member, which changes the opening area of the communicating port by changing of the variable member in response to a predetermined change in environmental conditions.

The example developing device may be configured to circulate a developer in accordance with the usage environment, such that excessive developer is prevented from being discharged, and a constant amount of developer may be maintained in the developing device.

A developer may change its bulk density depending on the usage environment. For example, under a usage environment at a low temperature, a developer may increase its bulk. Therefore, under a usage environment at a low temperature, a variable member may be used to increase the opening area of a communicating port in order to finely adjust the opening area of the communicating port. Accordingly, an amount of developer that passes through the communicating port may be increased in response to an increased bulk of developer.

Further, by using a variable member that can change the opening area of the communicating port in response to a predetermined change in environmental conditions, a conventional actuator for adjusting the opening area of the communicating port may be omitted, thereby providing a cost reduction or space-savings.

In some examples, a developer discharge port for discharging excessive developer is formed downstream in a conveyance direction from the first communicating port in the first accommodation space. The variable member may be provided to the first communicating port changes to increase the opening area of the first communicating port when the temperature of the variable member is lower than a predetermined temperature. Additionally, the variable member may be configured to decrease the opening area of the first communicating port when the temperature is higher than the predetermined temperature.

In some examples, the variable member may be provided to the first communicating port positioned near the developer discharge port for discharging excessive developer. The variable member may be configured to change and increase the opening area of the first communicating port at a low temperature. On the other hand, the variable member may be configured to decrease the opening area at a high temperature.

In some examples, a developer may increase its bulk at a low temperature. In order to prevent excessive developer from passing over the first communicating port and going to the developer discharge port, the opening area of the first communicating port is increased at a low temperature. This prevents the excessive developer from being discharged in order to maintain a constant amount of developer within the developing device.

A developer discharge port for discharging excessive developer may be formed downstream in a conveyance direction from the first communicating port in the first accommodation space. The variable member provided to the second communicating port changes to decrease the opening area of the second communicating port when the temperature of the variable member is lower than a predetermined temperature, and changes to increase the opening area of the second communicating port when the temperature is higher than the predetermined temperature.

In some examples, the variable member is provided to the second communicating port positioned distant from the developer discharge port for discharging excessive developer. The variable member changes to decrease the opening area of the second communicating port at a low temperature and changes to increase the opening area at a high temperature.

A developer may increase its bulk at a low temperature. In order to reduce an amount of developer that is conveyed from the second accommodation space through the second communicating port to the first accommodation space, the opening area of the second communicating port is decreased at a low temperature. This prevents the excessive developer from being discharged in order to maintain a constant amount of developer within the developing device.

In some examples, the variable member changes the opening area of the communicating port within the range of approximately 3.0 to 5.0% in response to a temperature change of the variable member.

The opening area of the communicating port may be changed in the range of approximately 3.0 to 5.0% as the variable member changes its temperature. Accordingly, the opening area of the communicating port can be appropriately changed in response to a change of usage environment.

In some examples, the variable member is formed of a substance having a coefficient of linear expansion of approximately 100 × 10^-6 or more.

A substance having a coefficient of linear expansion of approximately 100 × 10^-6 or more may be used to form the variable member in order to change the opening are of the communicating port in response to a change of usage environment.

Additionally, the variable member may be configured to change circumferentially along an inner surface of the first accommodation space or the second accommodation space.

The variable member may change circumferentially along an inner surface of the first accommodation space or the second accommodation space. For example, the variable member may be changed in a direction perpendicular to the conveyance direction of the developer.

In some examples, the amount of developer can be kept constant regardless of changes of environmental conditions.

Fig. 1 illustrates an image forming apparatus 1 which forms a color image using toner cartridges N for respective colors including magenta, yellow, cyan and black. The image forming apparatus 1 forms an image on paper P as a recording medium.

The image forming apparatus 1 has a recording medium feeding unit 10, developing devices 20 for developing an electrostatic latent image, and a transfer unit 30 for secondary transfer of a toner image on the paper P. Additionally, the image forming apparatus 1 may include photosensitive drums 40 as an electrostatic latent image carrier having an image formed on an outer circumferential surface thereof, and a fixing unit 50 for fixing the toner image on the paper P.

The recording medium feeding unit 10 conveys the paper P, on which an image is to be formed, on a feeding path R1. The paper P is stacked and contained in a cassette K, and picked up and fed by a paper feeding roller. The recording medium feeding unit 10 allows the paper P to arrive at a secondary transfer region R2 through the feeding path R1 in such a timing when a toner image to be transferred to the paper P arrives at the secondary transfer region R2.

In some examples, a separate developing device is provided for each of four colors. Each developing device 20 has a developing roller 21 for allowing toner to be carried on a photosensitive drum 40. The developing device 20 adjusts a mixing ratio of toner and carrier to a particular ratio. The developing device 20 may be configured to adjust a developer to include a uniform amount of toner and a particular charge amount. This developer is carried on the developing roller 21. When the rotation of the developing roller 21 conveys the developer to a region facing the photosensitive drum 40, toner of the developer carried on the developing roller 21 is moved onto the electrostatic latent image formed on the outer circumferential surface of the photosensitive drum 40, and the electrostatic latent image is developed.

The transfer unit 30 conveys a toner image formed by the developing device 20 to the secondary transfer region R2 where the toner image is to be secondarily transferred to the paper P. The transfer unit 30 has a transfer belt 31, suspending

rollers

31a, 31b, 31c and 31d suspending the transfer belt 31, a primary transfer roller 32 holding the transfer belt 31 together with the photosensitive drum 30, and a secondary transfer roller 33 holding the transfer belt 31 with the suspending roller 31d.

The transfer belt 31 is an endless belt, which is circularly moved by suspending

rollers

31a, 31b, 31c and 31d. The primary transfer roller 32 is provided so as to press the photosensitive drum 40 from an inner circumference of the transfer belt 31. The secondary transfer roller 33 is provided so as to press the suspending roller 31d from an outer circumference of the transfer belt 31.

In some examples, a separate photosensitive drum 40 is provided for each of four colors (e.g., magenta, yellow, cyan and black). Each photosensitive drum 40 is provided along a moving direction of the transfer belt 31. The developing device 20, a charging roller 41, an exposure unit 42 and a cleaning unit 43 are provided on the photosensitive drum 40.

The charging roller 41 may be configured to uniformly charge the surface of the photosensitive drum 40 at a predetermined electric potential. The charging roller 41 moves while following the rotation of the photosensitive drum 40. The exposure unit 42 exposes the surface of the photosensitive drum 40 charged by the charging roller 41 in accordance with an image to be formed on the paper P. This changes the electric potential of a portion of the surface of the photosensitive drum 40 which has been exposed by the exposure unit 42, to form an electrostatic latent image. Four developing devices 20 develop an electrostatic latent image formed on the photosensitive drum 40 by toner supplied from toner cartridges N provided to face respective developing devices 20, so that a toner image is generated. Each toner cartridge N is filled with one of the magenta, yellow, cyan and black toners. The cleaning unit 43 collects toner remaining on the photosensitive drum 40 after the toner image formed on the photoreceptor toner 40 is primarily transferred to the transfer belt 31.

The fixing unit 50 adheres and fixes the toner image, which is secondarily transferred from the transfer belt 31 to the paper P. The fixing unit 50 has a heating roller 51 for heating the paper P and a pressing roller 52 for pressing the heating roller 51. The heating roller 51 and the pressing roller 52 are formed in a cylindrical shape, and the heating roller 51 has a heat source such as a halogen lamp. A fixing nip portion provides a contact region between the heating roller 51 and the pressing roller 52. When the paper P is passed through the fixing nip portion, the toner image is fused and fixed on the paper P. After secondarily transferring the toner image on the paper P, toner remaining on the transfer belt 31 is collected by a belt cleaning device.

Additionally, the image forming apparatus 1 may be provided with

discharge rollers

53, 54 for discharging the paper P having the toner image fixed by the fixing unit 50 to the outside of the apparatus.

Printing Operations

Next, example printing operations of the image forming apparatus 1 are described. Upon input of an image signal of an image to be recorded into the image forming apparatus 1, the image forming apparatus 1 rotates the paper feeding roller, and picks up and conveys the paper P stacked in the cassette K. Then, based on the received image signal, the charging roller 41 uniformly charges the surface of the photosensitive drum 40 at a predetermined electric potential (charging process). Thereafter, the exposure unit 42 applies laser light to the surface of the photosensitive drum 40 to form an electrostatic latent image (exposure process).

In the developing device 20, the electrostatic latent image is developed, so that a toner image is formed (developing process). The thus-formed toner image is initially transferred from the photosensitive drum 40 to the transfer belt 31 in a region where the photosensitive drum 40 and the transfer belt 31 face each other (transfer process). Toner images formed on four photosensitive drums 40 are sequentially overlaid on the transfer belt 31, so that a single overlaid toner image is formed. Then, the overlaid toner image is secondarily transferred to the paper P fed from the recording medium feeding unit 10 in the secondary transfer region R2 where the suspending roller 31d and the secondary transfer roller 33 face each other.

The paper P having the overlaid toner image secondarily transferred thereon is conveyed to the fixing unit 50. The paper P is passed between the heating roller 51 and the pressing roller 52 while heat and pressure are applied to the paper; and thereby, the overlaid toner image is fused and fixed onto the paper P (fixing process). Thereafter, the paper P is discharged by the

discharge rollers

53, 54 to the outside of the image forming apparatus 1.

Developing Device

As illustrated in Fig. 2, the developing device 20 has a housing 60, a developing roller 21, a first conveyance member 70 and a second conveyance member 75. Fig. 2 schematically illustrates each constituent element for ease of explanation of a circulation state of toner.

The housing 60 may be formed in the shape of an oblong container. The housing 60 has a partition 60a for dividing an inner space of the housing into upper and lower portions. In the housing 60, a first accommodation space S1 is formed on the upper side of the partition 60a and a second accommodation space S2 is formed on the lower side of the partition 60a.

The first accommodation space S1 contains the developing roller 21 and the first conveyance member 70. The second accommodation space S2 contains the second conveyance member 75. A portion of the housing 60 containing the first conveyance member 70 forms a first housing portion 61 and a portion of the housing 60 containing the second conveyance member 75 forms a second housing portion 62.

The housing 60 is formed with a developer feeding port 63, a first communicating port 64, a second communicating port 65 and a developer discharge port 66. Additionally, the second communicating port 65 is formed near one end of the longitudinal direction of the housing 60. The developer feeding port 63, the first communicating port 64 and the developer discharge port 66 are formed near the other end of the longitudinal direction of the housing 60.

The developer feeding port 63 is formed in the second housing portion 62. The developer feeding port 63 includes an opening for feeding a developer supplied from a toner cartridge N to the second accommodation space S2. In some examples, the developer may contain a magnetic carrier and a non-magnetic toner.

The first communicating port 64 is formed in the partition 60a. The communicating port 64 is placed between the second communicating port 65 and the developer discharge port 66. The first communicating port 64 fluidly couples the first accommodation space S1 with the second accommodation space S2. The first communicating port 64 includes an opening for feeding the developer conveyed by the first conveyance member 70 to the second accommodation space S2.

The second communicating port 65 is formed in the partition 60a. The second communicating port 65 fluidly couples the first accommodation space S1 with the second accommodation space S2. The second communicating port 65 includes an opening for feeding the developer conveyed by the second conveyance member 75 to the first accommodation space S1.

The developer discharge port 66 is formed in the first housing portion 61. The developer discharge port 66 includes an opening for conveying excessive developer from the first accommodation space S1 to a waste toner box 45 (schematically illustrated in Fig. 2).

The developing roller 21 includes a developer carrier for supplying toner to an electrostatic latent image formed on the outer circumferential surface of the photosensitive drum 40 as an image carrier. The developing roller 21 is placed at an upper portion of the first accommodation space S1 so as to face the photosensitive drum 40.

The first conveyance member 70 stirs and mixes a developer in the first accommodation space S1, and also conveys the developer. The developer stirred and mixed by the first conveyance member 70 is supplied to the developing roller 21. Further, the developer conveyed by the first conveyance member 70 is conveyed to the second accommodation space S2 through the first communicating port 64.

The first conveyance member 70 has a first support shaft 71 and a first conveyance blade 72. The first support shaft 71 extends horizontally along the partition 60a. The first support shaft 71 is rotatably supported by a bearing (not illustrated). The first conveyance blade 72 is formed on an outer circumferential surface of the first support shaft 71. The first conveyance blade 72 has a spiral-shaped inclined surface arranged along an axial direction of the first support shaft 71. The first conveyance blade 72 conveys a developer from the second communicating port 65 toward the first communicating port 64 (in a forward direction).

The first support shaft 71 has a first counter blade 73 formed on the outer circumferential surface thereof. The first counter blade 73 is provided between the first communicating port 64 and the developer discharge port 66. The first counter blade 73 conveys a developer in a direction opposite to the forward direction of the first conveyance blade 72. For example, the first counter blade 73 prevents the developer present between the second communicating port 65 and the first communicating port 64 from moving to the developer discharge port 66.

However, when the amount of developer in the first accommodation space S1 is larger than a predetermined amount, excessive developer passes over the first counter blade 73 and is conveyed to the developer discharge port 66. The excessive developer conveyed to the developer discharge port 66 is collected into the waste toner box 45.

The second conveyance member 75 stirs and mixes a developer in the second accommodation space S2 and conveys the developer. The developer stirred and mixed by the second conveyance member 75 is supplied to the first accommodation space S1 through the second communicating port 65.

The second conveyance member 75 has a second support shaft 76 and a second conveyance blade 77. The second support shaft 76 extends horizontally along the partition 60a. The second support shaft 76 is rotatably supported by a bearing (not illustrated). The second conveyance blade 77 is formed on an outer circumferential surface of the second support shaft 76. The second conveyance blade 77 has a spiral-shaped inclined surface arranged along an axial direction of the second support shaft 76. The second conveyance blade 77 conveys a developer from the first communicating port 64 toward the second communicating port 65.

The second support shaft 76 has a second counter blade 78 formed on an outer circumferential surface thereof. The second counter blade 78 is provided downstream from the second communicating port 65 in the second accommodation space S2. The second counter blade 78 conveys a developer in a direction opposite to the forward direction of the second conveyance blade 77. For example, the second counter blade 78 promotes the movement of a developer, which has been conveyed from the first communicating port 64 toward the second communicating port 65, to the first accommodation space S1 through the second communicating port 65.

A developer may change its bulk density depending on the usage environment. For example, under a usage environment at a low temperature, a developer tends to increase its bulk. Thus, in response to an increased bulk of developer, an opening area of the first communication port 64 or the second communicating port 65 may be finely adjusted.

Fig. 3 illustrates a variable member 80 configured to change the opening area of the first communicating port 64 in response to a predetermined change in environmental conditions. The variable member 80 is formed as a plate extendable along a lower surface of the partition 60a, and an end of the variable member distant from the first communicating port 64 is fixed to the partition 60a.

Then, under a temperature condition where the housing 60 of the developing device 20 has an interior temperature higher than a predetermined temperature, a tip of the variable member 80 is arranged so as to project into the first communicating port 64 and to cover part of the first communicating port 64, therefore decreasing the opening area of the first communicating port 64.

Fig. 4 illustrates a temperature condition where the housing 60 of the developing device 20 has an interior temperature lower than the predetermined temperature, and the variable member 80 contracts along a lower surface of the partition 60a. Accordingly, the tip of the variable member 80 moves to a position where it does not overlap the first communicating port 64 in planar view, thereby increasing the opening area of the first communicating port 64.

Movement of the tip of the variable member 80 can be used to finely adjust the opening area of the first communicating port 64 so as to increase an amount of developer that passes through the first communicating port 64 in response to an increased bulk of developer caused by a temperature decrease inside the housing 60. As a result, excessive developer is prevented from passing over the first communicating port 64 and moving to the developer discharge port 66, and a constant amount of developer can be maintained within the developing device 20.

A material of the variable member 80 used herein may be selected depending on the degree of change in the opening area of the first communicating port 64. For example, ABS has a coefficient of linear expansion of 74 × 10^-6; rubber has a coefficient of linear expansion of 110 × 10^-6; and polyethylene has a coefficient of linear expansion of 180 × 10^-6.

When the variable member 80 has a full length of 150 mm and the developing device 20 has an interior temperature of 20℃, the variable member 80 may have a variation size "a" of approximately 0.22 mm for ABS, 0.33 mm for rubber and 0.54 mm for polyethylene.

The variable member 80 may be formed of a substance having a coefficient of linear expansion of 100 × 10^-6 or more, and thus, among the above-described materials, may include rubber or polyethylene. As a polyethylene material, commercially available polyethylene such as "HARMOREX" (registered trademark) NJ744N manufactured by Japan Polyethylene Corporation may be used.

In addition, the opening area of the first communicating port 64 may be changed within the range of approximately 3.0 to 5.0% along with temperature changes of the variable member 80.

The first communicating port 64 may be formed in the form of, for example, a rectangular. As illustrated in Fig. 3, the variable member 80 covers part of the first communicating port 64, and thereby, the first communicating port 64 has an opening area of approximately 5 × 10 = 50 mm².

When the variable member 80 has a variation size "a" of approximately 0.5 mm when it contracts as illustrated in Fig. 4, the first communicating port 64 has an opening area of approximately 5 × 10.5 = 52.5 mm². Therefore, when polyethylene having a variation size "a" of approximately 0.54 mm, for example, is used as a material for the variable member 80, the opening area of the first communicating port 64 can be increased by approximately 5%.

As previously described, the opening area of the second communicating port 65 may be changed. As illustrated in Fig. 5, a variable member 85 is placed near the second communicating port 65. The variable member 85 has a shutter plate 86 along a lower surface of the partition 60a, and a plate-like variable portion 87 extendable along a lower surface of the shutter plate 86.

The shutter plate 86 is movable along the lower surface of the partition 60a so as to cover part of the second communicating port 65 in an openable and closable manner. The variable portion 87 may be formed of a material having the same characteristic as that of the variable member 80 provided to the first communicating port 64. Under a temperature condition where the housing 60 of the developing device 20 has an interior temperature lower than the predetermined temperature, the variable portion 87 contracts along the lower surface of the partition 60a.

The variable portion 87 has an end near the second communicating port 65, which is fixed to the partition 60a. In addition, the variable portion 87 has an end distant from the second communicating port 65, which is fixed to the shutter plate 86. A contraction of the variable portion 87 allows a tip of the shutter plate 86 to project into the second communicating port 65 and to move so as to cover part of the second communicating port 65 (see Fig 6).

Under a temperature condition where the housing 60 of the developing device 20 has an interior temperature higher than a predetermined temperature, the tips of the variable portion 87 and the shutter plate 86 do not project into the second communicating port 65, as illustrated in Fig. 5, thereby increasing the opening area of the second communicating port 65.

As illustrated in Fig. 6, under a temperature condition where the housing 60 of the developing device 20 has an interior temperature lower than the predetermined temperature, contraction of the variable portion 87 along the lower surface of the partition 60a allows the tip of the shutter plate 86 fixed to the variable portion 87 to project into the second communicating port 65 and move to such a position that part of the second communicating port 65 is covered. Accordingly, the opening area of the communicating port 65 is decreased.

The projection and movement of the tip of the shutter plate 86 can be used to finely adjust the opening area of the second communicating port 65 so as to decrease an amount of developer that passes through the second communicating port 65 positioned distant from the developer discharge port 66 in response to an increased bulk of developer caused by a temperature decrease inside the housing 60. As a result, the amount of developer to be fed into the first accommodation space S1 may be maintained at a relatively constant level, without large increases.

Fig. 7 is a graph illustrating an example relationship between the number of prints and the weight of developer. When the weight of developer is below a dotted line indicated in Fig. 7, the ability of the developing roller 21 to carry a developer and the quality of image formation are both decreased.

As illustrated in Fig. 7, when the first communicating port 64 and the second communicating port 65 have a constant opening area, and as the number of prints is increased, excessive developer may be discharged so that the weight of the developer is decreased.

On the other hand, when the opening areas of the first communicating port 64 and the second communicating port 65 are varied by providing a variable member (80, 85), excessive developer is prevented from being discharged, thereby maintaining the approximately constant amount of developer within the developing device 20.

Fig. 8 is a cross-sectional side view illustrating a configuration of another example variable member, with like reference numerals being given to like portions, and with differences from the prior examples being explained.

As illustrated in Fig. 8, a variable member 80 is provided near a first communicating port 64 to change the opening area of the first communicating port 64 in response to a predetermined change in environmental conditions. The variable member 80 is formed in the form of a plate that is circumferentially extendable along an inner surface of a first accommodation space S1, and a right end of the first communicating port 64 in Fig. 8 is fixed to a partition 60a. This allows the variable member 80 to change along an inner wall surface of the first accommodation space S1 in a direction perpendicular to a conveyance direction of a developer.

Under a temperature condition where the housing 60 of the developing device 20 has an interior temperature higher than a predetermined temperature, the variable member 80 has a left end in Fig. 8, which is arranged to project into the first communicating port 64 to cover part of the first communicating port 64 (see the virtual line in Fig. 8). Therefore, the opening area of the first communicating port 64 is decreased.

Under a temperature condition where the housing 60 of the developing device 20 has an interior temperature lower than the predetermined temperature, the variable member 80 contracts circumferentially along the inner surface of the first accommodation space S1, and the variable member 80 moves to such a position as not to overlap the first communicating port 64. Therefore, the opening area of the first communicating port 64 is increased.

Movement of the variable member 80 can be used to finely adjust the opening area of the first communicating port 64 so as to increase an amount of developer that passes through the first communicating port 64 in response to an increased bulk of developer caused by a temperature decrease inside the housing 60. As a result, excessive developer is prevented from passing over the first communicating port 64 and moving to the developer discharge port 66, and a substantially constant amount of developer may be maintained within the developing device 20.

In some examples, a variable member 85 provided to a second communicating port 65 may be configured such that a shutter plate 86 is fixed to a variable portion 87.

It is to be understood that not all aspects, advantages and features described herein may necessarily be achieved by, or included in, any one particular example. Indeed, having described and illustrated various examples herein, it should be apparent that other examples may be modified in arrangement and detail is omitted. For example, the variable member 80 may be arranged along the lower surface of the partition 60a, and the variable member 80 may be arranged along an upper surface of the partition 60a. Further, a portion of the partition 60a may be notched so that the notched portion has the same length as the variable member 80, and the variable member 80 may be fitted into the notched portion. In some examples, the variable member 80 forms a portion of the partition 60a, which partitions into a first accommodation space S1 and a second accommodation space S2.

Claims

A developing device for an imaging system, comprising:

a housing having an accommodation space and a partition to partition the accommodation space into a first accommodation space and a second accommodation space, the partition being formed with a first communicating port and a second communicating port spaced apart from each other to fluidly couple the first accommodation space with the second accommodation space;

a first conveyance member contained in the first accommodation space to convey developer located within the first accommodation space from the second communicating port toward the first communicating port; and

a second conveyance member contained in the second accommodation space to convey developer located within the second accommodation space from the first communicating port toward the second communicating port,

wherein at least one of the first and second communicating ports is provided with a variable member to change a communicating port opening area in response to a predetermined change in environmental conditions.
The developing device according to claim 1, further comprising:

a developer discharge port to discharge excessive developer, the developer discharge port located downstream from the first communicating port in a conveyance direction of the developer located in the first accommodation space,

the variable member provided to the first communicating port to increase an opening area of the first communicating port when the temperature of the variable member is lower than a predetermined temperature, and to decrease the opening area of the first communicating port when the temperature is higher than the predetermined temperature.
The developing device according to claim 1, further comprising:

a developer discharge port to discharge excessive developer, the developer discharge port located downstream from the first communicating port in a conveyance direction of the developer located in the first accommodation space,

the variable member provided to the second communicating port to decrease an opening area of the second communicating port when the temperature of the variable member is lower than a predetermined temperature, and to increase the opening area of the second communicating port when the temperature is higher than the predetermined temperature.
The developing device according to claim 1,

the variable member to change the communicating port opening area within a range of approximately 3.0 to 5.0% in response to a temperature change of the variable member.
The developing device according to claim 1,

wherein the variable member is formed of a substance having a coefficient of linear expansion of 100 × 10^-6 or more.
The developing device according to claim 1,

the variable member to change circumferentially along an inner surface of the first accommodation space or along an inner surface of the second accommodation space.
The developing device according to claim 1,

the first conveyance member located in the first accommodation space to convey, while stirring, the developer located within the first accommodation space, and

the second conveyance member located in the second accommodation space to convey, while stirring, the developer located within the second accommodation space.
A developing device for an imaging system, comprising:

a housing having an accommodation space and a partition to partition the accommodation space into a first accommodation space and a second accommodation space, the partition including a first communicating port and a second communicating port to fluidly couple the first accommodation space with the second accommodation space;

a first conveyance member located in the first accommodation space to convey developer at least partially contained within the first accommodation space from the second communicating port toward the first communicating port;

a second conveyance member located in the second accommodation space to convey developer at least partially contained within the second accommodation space from the first communicating port toward the second communicating port; and

a communicating port opening which changes in area in response to a change in environmental conditions.
The developing device according to claim 8,

wherein the first communicating port is spaced apart from the second communicating port.
The developing device according to claim 8, further comprising:

a developer discharge port to discharge excessive developer, the developer discharge port located downstream from the first communicating port in a conveyance direction of the developer contained in the first accommodation space.
The developing device according to claim 10, further comprising:

a variable member to change the area of the communicating port opening, the variable member to change in size in response to a change in temperature,

wherein the variable member is provided to the first communicating port to increase an opening area of the first communicating port when the temperature of the variable member is lower than a predetermined temperature, and to decrease the opening area of the first communicating port when the temperature is higher than the predetermined temperature.
The developing device according to claim 10, further comprising:

a variable member to change the area of the communicating port opening, the variable member to change in size in response to a change in temperature,

wherein the variable member is provided to the second communicating port to decrease an opening area of the second communicating port when the temperature of the variable member is lower than a predetermined temperature, and to increase the opening area of the second communicating port when the temperature is higher than the predetermined temperature.
The developing device according to claim 8, further comprising:

a variable member to change the area of the communicating port opening, the variable member to change in size in response to a change in temperature.
The developing device according to claim 13,

wherein the variable member is attached to and extends along a lower surface of the partition.
The developing device according to claim 13,

wherein the variable member comprises a tip, the tip to project into and partially cover the communicating port opening to decrease the area of the communicating port opening.
The developing device according to claim 13,

wherein the variable member is made of rubber or polyethylene.