JP2019159213A - Developing device and image forming apparatus - Google Patents

Abstract

To suppress the excessive discharge of a developer in comparison with a case where the developer scattered in a storage part flows out to the outside of the storage part through a discharge part as it is.SOLUTION: A developing device includes the storage part which stores the developer for forming an image on an image holder, a conveyance part which is rotated in the storage part, to convey the developer in a conveyance direction, the discharge part which is provided in the storage part, faces the conveyance part, is opened toward the outside of the storage part in a direction crossing the conveyance direction, and discharges the developer exceeding a predetermined bulk height from the storage part, and suppression means which changes the travel direction of the developer toward the outside of the storage part in the discharge part, to suppress the discharge of the developer from the discharge part.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a developing device and an image forming apparatus.

  As a conventional technique, there is a developing device that adjusts the amount of the developer stored in the storage unit by discharging the developer exceeding a predetermined bulkiness from a discharge unit provided in the storage unit. Patent Document 1 discloses a developing device that circulates and conveys a developer containing a carrier and toner in a developing container, and discharges excess developer accompanying the replenishment of the developer to the developing container from the developing container through a discharge port. Is disclosed.

JP 2009-86180 A

By the way, in the developing device, for example, when the conveyance unit that conveys the developer is rotated at a high speed, the developer is scattered in the accommodation unit. Then, if the developer scattered in the storage portion flows out of the storage portion through the discharge portion as it is, it leads to excessive discharge of the developer and a decrease in the developer amount.
An object of the present invention is to suppress excessive discharge of the developer as compared with a case where the developer scattered in the storage portion flows out of the storage portion through the discharge portion as it is.

The invention according to claim 1 is provided in the storage unit that stores a developer that forms an image on an image carrier, a transport unit that rotates in the storage unit and transports the developer in the transport direction, and the storage unit. A discharge unit that faces the transport unit and opens in a direction intersecting the transport direction toward the outside of the storage unit, and discharges the developer exceeding a predetermined bulkiness from the storage unit, and the discharge unit In the developing device, the developing device includes a suppressing unit that suppresses discharge of the developer from the discharge unit by changing a traveling direction of the developer toward the outside of the storage unit.
The invention according to claim 2 is characterized in that the suppressing means suppresses the discharge of the scattered developer scattered in the accommodating portion by the rotation of the conveying portion from the discharge portion. Device.
According to a third aspect of the present invention, the suppressing means suppresses the discharge of the scattered developer from the discharge portion by guiding the scattered developer from the discharge portion to the outside of the storage portion into the storage portion. The developing device according to claim 2, wherein:
The invention according to claim 4 is provided in the storage unit that stores a developer that forms an image on the image carrier, a transport unit that rotates in the storage unit and transports the developer in the transport direction, and the storage unit. A discharge unit that faces the transport unit and opens in a direction intersecting the transport direction toward the outside of the storage unit, and discharges the developer exceeding a predetermined bulkiness from the storage unit, and the discharge unit The developing device comprises a plate-like member provided to be inclined with respect to the transport direction, and a suppressing means for suppressing discharge of the developer from the discharge portion.
The invention according to claim 5 is the developing device according to claim 4, wherein the suppressing unit is configured by a plurality of the plate-like members arranged in the transport direction with a gap therebetween.
According to a sixth aspect of the present invention, the suppressing means has a projection area of the plate-like member as seen from the developer discharging direction at the discharging portion becoming larger from the downstream side to the upstream side in the transport direction. The developing device according to claim 6, wherein:
The invention according to claim 7 is characterized in that, in the suppressing means, the gaps between the plurality of plate-like members become smaller from the downstream side to the upstream side in the transport direction. Development apparatus.
The invention according to claim 8 is characterized in that, in the suppression means, an angle formed between each plate-like member and the transport direction becomes smaller from the downstream side to the upstream side in the transport direction. A developing device according to claim 6.
The invention according to claim 9 is characterized in that the housing portion has a wall portion that is located below the gravitational direction of the plate-like member and extends in the gravitational direction from the lower end of the discharging portion in the gravitational direction, 5. The developing device according to claim 4, wherein a horizontal plane is not formed.
The invention according to claim 10 is characterized in that the wall portion of the accommodating portion is inclined so as to approach the transport portion as it goes from the lower end of the discharge portion toward the gravitational direction. The developing device described.
The invention according to claim 11 is characterized in that an upper end of the wall portion of the housing portion in the gravitational direction is located outside the housing portion with respect to the plate-like member. It is a developing device.
According to a twelfth aspect of the present invention, the transport unit includes a rotation shaft extending in the transport direction and a transport blade formed in a spiral shape on the outer periphery of the rotation shaft, and the suppressing unit is arranged in the upper direction of the gravity direction. 5. The developing device according to claim 1, wherein the developing device is formed of a plate-like member that is inclined with respect to a direction perpendicular to the conveying blade located at the position.
A thirteenth aspect of the invention includes an image carrier and a developing device that forms an image on the image carrier using a developer, and the developing device is the developing device according to any one of the first to twelfth aspects. An image forming apparatus configured by the apparatus.

According to the first and second aspects of the invention, it is possible to suppress the excessive discharge of the developer as compared with the case where the developer scattered in the storage portion flows out of the storage portion as it is through the discharge portion.
According to the third aspect of the present invention, it is possible to suppress a decrease in the developer amount as compared with the case where the scattering developer is not guided to the inside of the accommodating portion by the suppressing means.
According to the fourth aspect of the invention, it is possible to suppress the excessive discharge of the developer as compared with the case where the developer scattered in the storage portion flows out of the storage portion through the discharge portion as it is.
According to the invention which concerns on Claim 5, discharge | emission of the developer exceeding the predetermined bulkiness can be performed by the clearance gap between several plate-shaped members.
According to the inventions according to claims 6 to 8, it is possible to further suppress the discharge of the developer scattered in the accommodating portion as compared with the case where the projected area of the plate-like member is equal from the downstream side to the upstream side in the transport direction. it can.
According to the ninth aspect of the present invention, it is possible to suppress the scattered developer hitting the plate-like member from being deposited on the wall as compared with the case where a horizontal surface is formed on the wall.
According to the tenth aspect of the present invention, it is possible to make it easier for the developer that has hit the plate-like member to return to the accommodating portion as compared with the case where the wall portion is not inclined.
According to the eleventh aspect of the present invention, the developer hitting the plate-like member is moved to the outside of the containing portion as compared with the case where the upper end of the wall portion in the gravitational direction is located inside the containing portion rather than the plate-like member. It can suppress falling.
According to the twelfth aspect of the present invention, the developer scattered by the rotation of the conveying section is likely to directly hit the plate-shaped member as compared with the case where the plate-shaped member is not inclined with respect to the direction perpendicular to the conveying blade.
According to the thirteenth aspect of the present invention, it is possible to suppress the excessive discharge of the developer as compared with the case where the developer scattered in the storage portion flows out of the storage portion through the discharge portion as it is.

1 is a diagram illustrating an overall configuration of an image forming apparatus to which the exemplary embodiment is applied. FIG. 6 is a cross-sectional view of the developing device cut along a plane perpendicular to a conveyance direction by a first conveyance member. It is a perspective view of a developing device. FIG. 4 is a diagram when the developing device is viewed from a direction IV in FIG. 3. It is sectional drawing which cut | disconnected the 1st conveyance member, the discharge port, and the shielding part along the surface perpendicular | vertical to the conveyance direction by a 1st conveyance member. It is the figure which looked at the 1st conveyance member, the discharge port, and the shielding part from the VI direction of FIG. (A)-(b) is the figure which showed an example of the other form of the shielding part.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
(Configuration of image forming apparatus)
FIG. 1 is a diagram illustrating an overall configuration of an image forming apparatus 1 to which the exemplary embodiment is applied. An image forming apparatus 1 shown in FIG. 1 includes, for example, a single color printer that forms a single color image on a sheet, and includes an image forming unit 10 that forms an image corresponding to image data. In addition, the image forming apparatus 1 includes a control unit 50 that controls the entire image forming apparatus 1.

The image forming unit 10 includes a photosensitive layer on the surface, and forms an electrostatic latent image and holds a toner image, and a photosensitive drum 11 as an example of an image holding member, and the photosensitive drum 11 is charged with a predetermined potential. A charging device 12, an exposure device 13 for exposing the photosensitive drum 11 charged by the charging device 12 based on image data, a developing device 100 for developing an electrostatic latent image formed on the photosensitive drum 11, and The transfer device 15 for transferring the toner image formed on the photosensitive drum 11 to the sheet conveyed between the photosensitive drum 11 (transfer section Tp) and the surface of the photosensitive drum 11 after the transfer are cleaned. And a cleaning device 16. Further, the image forming unit 10 includes a developer container 17 that stores a replenishment developer to be replenished to the developing device 100. Here, the replenishment developer accommodated in the developer accommodating container 17 has a higher toner content ratio relative to the carrier than the developer accommodated in the developing device 100. Further, the image forming unit 10 includes a fixing device 20 that fixes the toner image transferred by the transfer device 15 to a sheet.
The configuration of the developing device 100 will be described in detail later.

In the image forming unit 10, under the control of the control unit 50, an image forming operation is performed as follows. First, the photosensitive drum 11 is charged at a predetermined potential by the charging device 12 while rotating in a predetermined direction (clockwise in FIG. 1). Based on the image data, the exposure device 13 scans and exposes the photosensitive drum 11. Thereby, an electrostatic latent image is formed on the photosensitive drum 11. Thereafter, the electrostatic latent image formed on the photosensitive drum 11 is developed by the developing device 100, and a toner image is formed on the photosensitive drum 11.
Next, the sheet is supplied to the transfer unit Tp. In accordance with this, the toner image formed on the photosensitive drum 11 is electrostatically transferred to the sheet by the transfer electric field formed by the transfer device 15.

Thereafter, the sheet on which the toner image is electrostatically transferred is conveyed to the fixing device 20. The toner image on the paper conveyed to the fixing device 20 receives heat and pressure by the fixing device 20 and is fixed on the paper.
On the other hand, the toner adhering to the photosensitive drum 11 after the transfer is removed by the cleaning device 16.
In this way, the image forming process in the image forming apparatus 1 is repeatedly executed for the number of printed sheets.

(Configuration of developing device)
2 to 4 are diagrams illustrating a developing device 100 to which the exemplary embodiment is applied. 2 is a cross-sectional view of the developing device 100 taken along a plane perpendicular to the conveyance direction by the first conveyance member 120 described later, FIG. 3 is a perspective view of the developing device 100, and FIG. FIG. In FIG. 4, the description of the collection unit 150 described later is omitted.
The developing device 100 of the present embodiment performs development using a so-called two-component developer whose main component is, for example, a negatively charged toner and a positively charged and magnetic carrier. Further, the developing device 100 is configured to be detachable from the main body of the image forming apparatus 1 (see FIG. 1).

The developing device 100 has an opening facing the photosensitive drum 11, and is disposed at a position facing the opening of the developing housing 110 and a developing housing 110 as an example of a housing portion in which the two-component developer is housed. And a developing roll 101 that faces the photosensitive drum 11 and a layer regulating member 102 that regulates the thickness of the developer layer held on the outer peripheral surface of the developing roll 101.
Further, the developing device 100 is arranged side by side in the direction of gravity (Z direction to be described later), and a first transport member 120 as an example of a transport unit that transports the two-component developer accommodated in the development housing 110 while stirring. And a second conveying member 130. Further, the developing device 100 includes a third conveying member 140 that conveys the developer staying between the developing roll 101 and the second conveying member 130 in the developing housing 110.
Furthermore, the developing device 100 includes a collecting unit 150 that collects the developer discharged from a discharge port 116 described later of the developing housing 110.

  Here, in the following description, as shown in FIGS. 2 to 4, the direction along the rotation axis of the developing roll 101 (the direction from the rear side to the front side of the image forming apparatus 1 (see FIG. 1)) is the X direction. Call it. Further, the direction of gravity in which the first transport member 120 and the second transport member 130 are arranged (the direction from the top to the bottom in FIGS. 2 to 4) is referred to as the Z direction. Further, a direction perpendicular to the X direction and the Z direction (a direction from left to right in FIG. 2) is referred to as a Y direction.

As shown in FIG. 3, the developing housing 110 includes a main body 110A in which the developing roll 101 is accommodated, and an extending part 110B extending in the X direction from one end of the main body 110A.
In addition to the developing roll 101, a first transport member 120, a second transport member 130, and a third transport member 140 are accommodated in the main body 110A. The main body 110A has a rectangular parallelepiped shape as a whole.
In addition, the ends of the first conveyance member 120 and the second conveyance member 130 that protrude from the main body 110A to the downstream side in the X direction are accommodated in the extension portion 110B. The extending portion 110B has a shape that follows the outer shape of the first transport member 120 and the second transport member 130, and specifically has a shape in which two cylinders are connected in the Z direction.

  The extension portion 110B is connected to the developer container 17 (see FIG. 1), and supplies a replenishment port 115 for replenishing the developer from the developer container 17 to the inside of the developing housing 110 (first stirring chamber 112 described later). Is formed. In this example, the supply port 115 opens toward the upstream side in the Z direction (upward in the direction of gravity).

Further, the extension portion 110B is formed with a discharge port 116 as an example of a discharge portion that discharges excess developer from the inside of the developing housing 110 (the first stirring chamber 112). In this example, the discharge port 116 opens to the downstream side in the Y direction from the inside of the developing housing 110 (first agitation chamber 112) to the collection unit 150 side. Further, the discharge port 116 is provided at the downstream end of the first transport member 120 in the X direction. Here, the discharge port 116 (discharge unit) facing the first conveying member 120 (conveying unit) means a state in which the discharge port 116 is formed on the wall surface of the developing housing 110 that houses the first conveying member 120. To do. Therefore, when the position of the discharge port 116 is shifted in the X direction (the axial direction of the first transfer member 120) or the Z direction (gravity direction) with respect to the first transfer member 120, the shape of the discharge port 116 is the first. The discharge port 116 is included in a state of facing the first transport member 120 even when it is not parallel to the transport member 120.
Although details will be described later, in this example, the wall located on the downstream side in the Z direction of the discharge port 116 (downward in the direction of gravity) of the wall surface of the extending portion 110B that surrounds the discharge port 116 and constitutes the discharge port 116. The lower wall surface 117 as an example of the portion is inclined from the inside to the outside of the developing housing 110 (see also FIG. 5 described later).
A collection unit 150 is connected to the outside of the discharge port 116. Further, the discharge port 116 is provided with a shielding portion 180 as an example of a suppressing unit that blocks a part of the discharge port 116 and suppresses the discharge of the developer via the discharge port 116. The configurations of the discharge port 116 and the shielding unit 180 will be described in detail later.

  In the extending portion 110B of the present embodiment, as shown in FIG. 4, the discharge port 116 is upstream of the replenishment port 115 in the developer transport direction by the first transport member 120 in the first stirring chamber 112. Arranged on the side. As a result, the new developer replenished from the replenishing port 115 is suppressed from being discharged from the discharge port 116 immediately after being replenished.

A partition wall 111 extending in the X direction from the main body portion 110A toward the extending portion 110B is formed inside the developing housing 110. In addition, a first stirring chamber 112 and a second stirring chamber 113 are formed inside the developing housing 110 by being partitioned by a partition wall 111. In this example, the first stirring chamber 112 and the second stirring chamber 113 are formed over substantially the entire X direction in the main body portion 110A and the extending portion 110B, respectively. Moreover, the 1st stirring chamber 112 and the 2nd stirring chamber 113 are arrange | positioned along with the Z direction (gravity direction). In this example, the first stirring chamber 112 is located on the upstream side in the Z direction (above the gravity direction) with respect to the second stirring chamber 113.
In addition, as shown in FIG. 4, the partition wall 111 has a first opening 111 </ b> A and a second opening 111 </ b> B at both ends in the X direction. Accordingly, the first stirring chamber 112 and the second stirring chamber 113 are connected to both ends in the X direction via the first opening 111A and the second opening 111B.

  In the first stirring chamber 112, a first transport member 120 is rotatably provided with the X direction as an axial direction. The second agitating chamber 113 is provided with a second transfer member 130 that is rotatable about the X direction as an axial direction. Further, in the second stirring chamber 113, a third transport member 140 is provided between the second transport member 130 and the developing roll 101 so as to be rotatable about the X direction as an axial direction.

  The first conveying member 120 includes a first shaft portion 121 as an example of a cylindrical rotating shaft whose axial direction is the X direction, and an example of a spiral conveying blade formed on the outer periphery of the first shaft portion 121. And a first blade portion 122. The first conveying member 120 rotates around the first shaft portion 121 and conveys the developer in a certain direction (direction from right to left in FIG. 4) while stirring the developer.

The second conveying member 130 includes a cylindrical second shaft portion 131 having the X direction as an axial direction, and a spiral second blade portion 132 formed on the outer periphery of the second shaft portion 131. The second conveying member 130 rotates about the second shaft 131 and conveys the developer in a certain direction (direction from left to right in FIG. 4) while stirring the developer.
As shown in FIG. 3, in the present embodiment, the lengths of the first transport member 120 and the second transport member 130 along the X direction are longer than those of the developing roll 101. Further, the interval between the first blade portions 122 in the first conveying member 120 and the interval between the second blade portions 132 in the second conveying member 130 are approximately the same.

  Next, the collection unit 150 will be described. The collection unit 150 includes a transport unit 151 that transports the developer discharged from the discharge port 116 of the developing housing 110, a guide unit 153 that guides the developer discharged from the discharge port 116 to the transport unit 151, and the discharge port 116. A recovery container 157 for recovering the developer discharged from.

The transport unit 151 has a columnar shape extending from the end of the guide unit 153 along the X direction. In addition, a collection conveyance member 155 that rotates around the X direction as an axial direction and conveys the developer discharged from the discharge port 116 to the upstream side in the X direction is provided inside the conveyance unit 151.
The guide unit 153 extends downward from the discharge port 116 of the developing housing 110 in the gravitational direction, and connects the discharge port 116 and one end (the end portion on the downstream side in the X direction) of the transport unit 151.
The collection container 157 is connected to the other end (upstream end in the X direction) of the transport unit 151 and stores the developer transported by the rotary transport member 155 in the transport unit 151.

(Developer circulation in the developing device)
Subsequently, the circulation of the developer in the developing device 100 of the present embodiment will be described.
When the first conveying member 120 and the second conveying member 130 are rotated by a driving unit (not shown), the developer in the second stirring chamber 113 is moved to the arrow by the rotation of the second conveying member 130 as shown in FIG. It is conveyed in the direction (upstream in the X direction, right direction in FIG. 4). At this time, the toner and carrier in the developer are agitated. Then, when the developer reaches the upstream end in the X direction in the second stirring chamber 113, the developer flows into the first stirring chamber 112 through the first opening 111 </ b> A.

  The developer that has flowed into the first stirring chamber 112 is transported in the direction of the arrow (downstream in the X direction, leftward in FIG. 4) by the rotation of the first transport member 120. As a result, the developer is conveyed to a portion facing the developing roll 101 while the toner and the carrier are agitated. A part of the developer being conveyed is supplied to the developing roll 101 and held on the outer peripheral surface of the developing roll 101 by a magnetic force. Further, the developer that has not been held on the developing roll 101 is further conveyed in the first stirring chamber 112 and reaches the downstream end portion in the X direction in the first stirring chamber 112, and then passes through the second opening 111B. It flows into the second stirring chamber 113. In this way, the developer circulates in the first stirring chamber 112 and the second stirring chamber 113 of the developing housing 110.

  Further, when the toner density of the developer in the developing housing 110 is lowered, the developer container 17 (see FIG. 1) is newly added to the developing device 100 under the control of the control unit 50 (see FIG. 1). Fresh developer is supplied. Specifically, a new developer is supplied from the developer container 17 into the first stirring chamber 112 of the development housing 110 through the supply port 115. The developer replenished from the replenishing port 115 is conveyed while being stirred together with the developer already in the first stirring chamber 112 and the second stirring chamber 113. As a result, the toner concentration of the developer in the developing housing 110 increases.

Further, a new developer is replenished from the replenishing port 115, and the excess developer due to an increase in the volume (bulk) of the developer in the developing housing 110 is discharged from the discharge port 116 to the collecting unit 150. Specifically, when the bulk of the developer exceeds the height (predetermined bulk height) of the lower wall surface 117 of the discharge port 116, the excess developer gets over the lower wall surface 117 and is collected from the discharge port 116. Overflow to the part 150 side. The bulkiness of the developer means the height of the developer surface of the developer conveyed in the first stirring chamber 112 in the gravity direction.
The developer discharged from the discharge port 116 is collected by the collection unit 150. Specifically, in the recovery unit 150, the developer discharged from the discharge port 116 is guided to the transport unit 151 via the guide unit 153, and transported by the recovery transport member 155 of the transport unit 151 to the recovery container 157. Collected.

As described above, the excess developer is discharged from the developing housing 110 and collected, thereby suppressing the volume (bulk) of the developer in the developing housing 110 from fluctuating.
The developer discharged from the discharge port 116 includes a carrier whose charging performance has deteriorated over a long period of use. Therefore, new developer is supplied from the supply port 115 and excess developer is discharged from the discharge port 116, so that the developer that has deteriorated in the development housing 110 is gradually replaced with new developer. Will be done.

By the way, in the developing device 100, the developer may rise from the surface of the developer and scatter in the developing housing 110 due to the rotation of the first conveying member 120 or the like. In some cases, the developer scattered in the developing housing 110 (hereinafter referred to as the scattered developer) is directed to the discharge port 116 and discharged from the discharge port 116 to the collecting unit 150. In particular, when the rotation speed of the first conveying member 120 and the like is increased as the image forming speed in the image forming apparatus 1 (see FIG. 1) is increased, the scattered developer is likely to be generated.
Then, for example, when the bulk of the developer does not reach the height of the lower wall surface 117 of the discharge port 116, if the scattered developer is discharged from the discharge port 116, the developer is excessively discharged from the development housing 110. As a result, the amount of developer in the developing housing 110 is reduced.

(Configuration of shielding part)
On the other hand, in the developing device 100 according to the present embodiment, the discharge port 116 is provided with a shielding portion 180 that suppresses the discharge of the scattered developer through the discharge port 116, thereby preventing the developer from being excessively discharged from the developing housing 110. Suppress.
Next, the shielding unit 180 will be described. FIG. 5 is a cross-sectional view of the first transport member 120, the discharge port 116, and the shielding unit 180 cut along a plane (ZY plane) perpendicular to the transport direction by the first transport member 120. 6 is a view of the first conveying member 120, the discharge port 116, and the shielding portion 180 as seen from the VI direction of FIG.

  As shown in FIGS. 5 and 6, the shielding unit 180 includes a plate-like member 181 that is inclined with respect to the developer conveyance direction (X direction) by the first conveyance member 120. In the present embodiment, the shielding part 180 has a plurality (three in this example) of plate-like members 181 arranged in the X direction with a gap. In this example, each plate member 181 has the same flat shape. Further, the angles at which the respective plate members 181 are provided are equal to each other, and the intervals between the adjacent plate members 181 are equal to each other. Further, each plate-like member 181 is supported by the guide part 153 of the collection part 150 and extends along the Z direction (gravity direction) so as to block the discharge port 116 from the wall surface of the guide part 153.

  Furthermore, when each plate-like member 181 of the shielding part 180 and the first conveying member 120 and the first blade part 122 are viewed from the upstream side in the Z direction (above the gravitational direction), each plate-like member 181 has the first The blade portion 122 is inclined with respect to a perpendicular P extending from a region (indicated by reference numeral 122A in FIG. 5) located above the gravity direction. In this example, each plate-like member 181 is provided so as to be perpendicular to the perpendicular P extending from the region 122 </ b> A of the first blade portion 122. In other words, each plate-like member 181 is provided in parallel with the region 122A of the first blade portion 122. This reason will be described later.

  As shown in FIG. 6, the position in the X direction of the inner end portion of the developing housing 110 in the plate member 181 is the same as the position of the outer end portion of the developing housing 110 in the adjacent plate member 181. Are equal. In other words, when the shielding part 180 of the present embodiment is viewed from the Y direction, the overlap between adjacent plate-like members 181 is reduced. Although details will be described later, by adopting such a configuration, discharge due to overflow of excess developer exceeding a predetermined bulkiness is hardly inhibited by the plate-shaped member 181.

  Next, the shape of the lower wall surface 117 of the discharge port 116 will be described. As shown in FIG. 5, the lower wall surface 117 is positioned above the gravitational direction and approaches the first transport member 120 from the upper end portion 117 </ b> A constituting the discharge port 116 toward the lower gravitational direction (downstream in the Z direction). So as to be inclined. Further, the lower wall surface 117 is not formed with a horizontal plane (a plane perpendicular to the Z direction). Furthermore, the upper end portion 117 </ b> A of the lower wall surface 117 is located on the outer side (the collection unit 150 side) of the developing housing 110 compared to the plate-like member 181 of the shielding unit 180. Although details will be described later, since the lower wall surface 117 has such a shape, the scattered developer that has struck the plate-shaped member 181 is difficult to be stacked on the lower wall surface 117, and returns to the developing housing 110 by the lower wall surface 117. It has become easier.

(Operation by shielding part)
Next, the behavior of the developer in the developing housing 110 and the action of suppressing the scattered developer discharge by the shielding unit 180 will be described.
When the first conveying member 120 is rotated, the developer is splashed by the first blade portion 122 of the first conveying member 120 on the surface of the developer accommodated in the developing housing 110, so that the developer is scattered. To do. When the scattered developer (scattered developer) travels toward the discharge port 116, the scattered developer abuts on the plate-like member 181 of the shielding portion 180 and changes its traveling direction, as indicated by the broken line arrow in FIG. . More specifically, the scattering developer falls down in the direction of gravity by hitting the plate-like member 181 of the shielding unit 180.

  Then, the scattered developer that has fallen against the plate-shaped member 181 is guided into the developing housing 110 by the lower wall surface 117 inclined toward the developing housing 110, and is stirred again together with the developer conveyed in the developing housing 110. It is conveyed while being.

On the other hand, when the bulk of the developer exceeds the height of the lower wall surface 117 in the development housing 110 due to the replenishment of the new developer, the excess developer is as indicated by the one-dot chain arrow in FIGS. Then, the gas is discharged from the discharge port 116 to the collection unit 150 through the gap between the plate-like members 181. As described above, each plate-like member 181 is inclined with respect to the X direction, so that the excess developer overflowed as compared with the case where each plate-like member 181 is parallel to the X direction. 181 hardly deposits.
As a result, in the present embodiment, the shielding portion 180 prevents the discharge due to the overflow of the excess developer exceeding the predetermined bulkiness in the developing housing 110 from being inhibited, while suppressing the discharge in the developing housing 110. Suppresses the scattering of scattered developer.

Here, as described above, each plate-like member 181 of the shielding portion 180 is preferably inclined with respect to the perpendicular P extending from the region 122A of the first blade portion 122.
This is due to the following reason. That is, the scattered developer that scatters from the surface of the developer by rotating the first conveying member 120 easily proceeds in a direction perpendicular to the first blade portion 122. In this example, the scattered developer tends to advance in the direction of a perpendicular line P extending from the region 122A of the first blade portion 122 located above the developer surface of the developer to the discharge port 116 side. Therefore, by providing the respective plate-like members 181 so as to be inclined with respect to the perpendicular P extending from the region 122A of the first blade portion 122, the scattering that is scattered by the first blade portion 122 and proceeds toward the discharge port 116. The developer is likely to hit the plate member 181. Thereby, the discharge of the scattered developer via the discharge port 116 is easily suppressed. Further, if each plate-like member 181 is provided so as to be perpendicular to the perpendicular P extending from the region 122A of the first blade portion 122, the scattered developer is likely to abut against each plate-like member 181. preferable.

Further, as described above, a horizontal plane is not formed on the lower wall surface 117 of the discharge port 116. Thereby, compared with the case where the lower wall surface 117 has a horizontal surface, it is suppressed that the scattering developer which collided with the plate-shaped member 181 and fell and laminated | stacked on the lower wall surface 117. FIG.
Further, the upper end portion 117 </ b> A of the lower wall surface 117 is located outside the developing housing 110 compared to the plate-like member 181 of the shielding portion 180. As a result, the scattered developer that has struck the plate-like member 181 easily falls on the lower wall surface 117. The scattered developer is easily guided into the developing housing 110 by the lower wall surface 117 inclined toward the first conveying member 120 side. Note that the surface of the lower wall surface 117 may be subjected to a surface treatment or the like for improving the slip of the developer.

By the way, as means for suppressing the discharge of the scattered developer from the discharge port 116, for example, the area of the discharge port 116 can be reduced in addition to the above-described shielding portion 180. However, when the area of the discharge port 116 is reduced, there is a possibility that discharge due to overflow of excess developer from the discharge port 116 may be insufficient.
Here, in the developing device 100, for example, the fluidity of the developer conveyed in the developing housing 110 varies depending on the image density, temperature, humidity, and other environments formed in the image forming unit 10 (see FIG. 1). There is a case. And when the fluidity | liquidity of a developer falls, if the area of the discharge port 116 is small, for example, it will become difficult to discharge | emit excess developer.

On the other hand, in this embodiment, since the discharge of the scattered developer is suppressed by the shielding unit 180, the area of the discharge port 116 can be increased as compared with the case where the shielding unit 180 is not provided. In other words, in the present embodiment, even when the area of the discharge port 116 is increased, the discharge of the scattered developer can be suppressed by the shielding unit 180.
In addition, since the area of the discharge port 116 can be increased, the amount of gas flowing inside and outside the developing device 100 through the discharge port 116 increases, so that an increase in pressure inside the developing device 100 is suppressed. As a result, it is possible to suppress the occurrence of cloud at the facing portion between the photosensitive drum 11 and the developing roll 101 as the pressure in the developing device 100 increases.

(Other forms of shielding)
Next, another form of the shielding unit 180 will be described.
In the example described above, the shapes and angles of the plurality of plate-like members 181 constituting the shielding part 180 are equal to each other, and the intervals between adjacent plate-like members 181 are equal to each other. Thereby, when the discharge port 116 and the shield part 180 are viewed from the developer discharge direction (Y direction in this example), the projected area of the shield part 180 (plate-shaped member 181) with respect to the area of the discharge port 116 (hereinafter, referred to as the following) The area is simply referred to as the projected area of the shielding portion 180) over the entire area of the discharge port 116.
However, the projected area of the shielding part 180 may be different between the upstream side and the downstream side in the X direction at the discharge port 116.

  Here, in the developing device 100 of the present embodiment, as described above, the discharge port 116 is disposed so as to face the downstream end portion of the first transport member 120 in the X direction. In the first stirring chamber 112, the developer is discharged from the upstream side in the X direction to the downstream side by the first transport member 120. For this reason, in the discharge port 116, the scattered developer scattered by the first transport member 120 tends to reach the upstream side more easily than the downstream side in the X direction.

Therefore, in order to suppress the discharge of the scattered developer from the discharge port 116, it is preferable to increase the projected area of the shielding part 180 on the upstream side compared to the downstream side in the X direction.
By increasing the projection area of the shielding part 180 on the upstream side compared to the downstream side in the X direction, the scattering developer is shielded on the shielding part 180 (upstream side in the X direction of the discharge port 116 where the scattering developer easily reaches. It becomes easy to hit the plate-like member 181). As a result, the discharge of the scattered developer is effectively suppressed on the upstream side of the discharge port 116 in the X direction. Further, since the projected area of the shielding portion 180 is smaller on the downstream side in the X direction of the discharge port 116 where the scattered developer is difficult to reach, the excess developer is easily discharged due to overflow. .

Next, an example in which the projected area of the shielding unit 180 is increased on the upstream side compared to the downstream side in the X direction will be specifically described. FIGS. 7A to 7B are diagrams showing an example of another form of the shielding unit 180, and are a diagram of the shielding unit 180 and the discharge port 116 seen from the Z direction.
In the example shown in FIG. 7A, the projected area of the shielding part 180 is made smaller than the downstream side in the X direction by reducing the interval between the plurality of plate-like members 181 on the upstream side compared to the downstream side in the X direction. It is larger on the upstream side. In other words, in the example illustrated in FIG. 7A, the interval between the plurality of plate-shaped members 181 increases from the upstream side in the X direction toward the downstream side.

  In the example shown in FIG. 7B, the angle formed by each plate-like member 181 and the developer transport direction (X direction) by the first transport member 120 is upstream compared to the downstream side in the X direction. As a result, the projected area of the shielding portion 180 is increased on the upstream side compared to the downstream side in the X direction. In other words, in the example shown in FIG. 7B, the angle formed by each plate-shaped member 181 and the X direction becomes larger from the downstream side in the X direction toward the upstream side.

In addition, although illustration is abbreviate | omitted, you may enlarge the projection area of the shielding part 180 upstream from the downstream of the X direction by making the shape of the several plate-shaped member 181 mutually differ, for example. For example, by increasing the area (width, height) of the plurality of plate-like members 181 on the upstream side compared to the downstream side in the X direction, the projected area by the shielding unit 180 is upstream compared to the downstream side in the X direction. Can be enlarged on the side.
Moreover, you may make the projection area of the shielding part 180 high in an upstream compared with the downstream of a X direction by combining said several form mutually.

As described above, in the developing device 100 of the present embodiment, by providing the shielding portion 180 at the discharge port 116 for discharging excess developer from the developing housing 110, the scattered developer generated in the developing housing 110 can be prevented. The discharge through the discharge port 116 is suppressed. Thereby, excessive discharge of the developer from the developing housing 110 and a decrease in the developer amount are suppressed.
Further, since the shielding portion 180 does not hinder the discharge due to the overflow of the excess developer through the discharge port 116, the change in the volume (bulk) of the developer is suppressed.

  In the above-described embodiment, the plate-like member 181 of the shielding unit 180 is supported by the guide unit 153 of the collection unit 150, but is not limited thereto. That is, the plate-like member 181 is supported by the collecting unit 150 even if it is supported by the developing housing 110 as long as it is arranged in a path from the discharge port 116 of the developing housing 110 to the guide unit 153 of the collecting unit 150. Also good.

  Moreover, although embodiment mentioned above demonstrated the example in which the shielding part 180 was comprised by the plate-shaped member 181 on a flat plate, the shielding part 180 is not restricted to this. In other words, the shielding portion 180 prevents the scattered developer from being discharged from the discharge port 116 by hitting the scattered developer scattered by the developing housing 110 and does not hinder discharge due to overflow of excess developer. If so, for example, a curved plate-like member or a rod-like member may be used.

  In the above description, the image forming apparatus 1 is a single color printer that forms a single color image on paper. However, the present embodiment can also be applied to a color printer that forms multiple color images on paper. it can. For example, in the present embodiment, a superimposed image obtained by superimposing a plurality of color toner images on an intermediate transfer member such as an intermediate transfer belt from a photosensitive drum is primarily transferred, and the superimposed image on the intermediate transfer member is collectively transferred to a sheet. The present invention can also be applied to an intermediate transfer type color printer that performs transfer (secondary transfer).

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 10 ... Image forming part, 100 ... Developing apparatus, 101 ... Developing roll, 110 ... Developing housing, 112 ... First stirring chamber, 113 ... Second stirring chamber, 116 ... Discharge port, 117 ... Lower wall surface , 120 ... 1st conveyance member, 130 ... 2nd conveyance member, 150 ... collection | recovery part, 180 ... shielding part, 181 ... plate-shaped member

Claims (13)

An accommodating portion for accommodating a developer that forms an image on the image carrier;
A transport section that rotates within the housing section and transports the developer in the transport direction;
Provided in the storage unit, facing the transport unit, opening in the direction intersecting the transport direction toward the outside of the storage unit, and discharging developer exceeding a predetermined bulkiness from the storage unit A discharge section;
A developing device comprising: a suppressing unit that suppresses discharge of the developer from the discharge unit by changing a traveling direction of the developer toward the outside of the storage unit in the discharge unit.   2. The developing device according to claim 1, wherein the suppressing unit suppresses discharge of the scattered developer scattered in the housing unit by rotation of the transport unit from the discharge unit.   The suppression unit suppresses discharge of the scattered developer from the discharge unit by guiding the scattered developer from the discharge unit toward the outside of the storage unit into the storage unit. The developing device according to 1. An accommodating portion for accommodating a developer that forms an image on the image carrier;
A transport section that rotates within the housing section and transports the developer in the transport direction;
Provided in the storage unit, facing the transport unit, opening in the direction intersecting the transport direction toward the outside of the storage unit, and discharging developer exceeding a predetermined bulkiness from the storage unit A discharge section;
A developing device comprising a plate-like member provided at an inclination with respect to the transport direction in the discharge unit, and a suppression unit that suppresses the discharge of the developer from the discharge unit.   The developing device according to claim 4, wherein the suppressing unit includes a plurality of the plate-like members arranged in the transport direction with a gap therebetween.   The said suppressing means, The projected area of the said plate-shaped member seen from the discharge direction of the developer in the said discharge part becomes large as it goes to the upstream from the downstream of the said conveyance direction, It is characterized by the above-mentioned. 5. The developing device according to 5.   The developing device according to claim 6, wherein the suppression unit has a gap between the plurality of plate-like members that decreases from the downstream side to the upstream side in the transport direction.   The developing device according to claim 6, wherein an angle formed between each plate-like member and the transport direction of the suppression unit decreases from the downstream side to the upstream side of the transport direction. .   The accommodating portion has a wall portion that is positioned below the gravitational direction of the plate-like member and extends in the gravitational direction from a lower end of the discharging portion in the gravitational direction, and a horizontal plane is not formed on the wall portion. The developing device according to claim 4.   The developing device according to claim 9, wherein the wall portion of the housing portion is inclined so as to approach the transport portion as it goes from the lower end of the discharge portion toward the gravitational direction.   The developing device according to claim 10, wherein an upper end of the wall portion of the housing portion in the gravitational direction is located outside the housing portion with respect to the plate-like member. The transport unit includes a rotation shaft extending in the transport direction, and a transport blade formed in a spiral shape on the outer periphery of the rotation shaft,
5. The developing device according to claim 1, wherein the suppressing unit includes a plate-like member that is inclined with respect to a direction perpendicular to the conveying blade located above the gravitational direction.   An image forming apparatus comprising: an image holding member; and a developing device that forms an image on the image holding member using a developer, wherein the developing device includes the developing device according to claim 1. .