Method for discharging developer from developing device and developing device

Abstract

To provide a configuration that can appropriately discharge developer even if the configuration is such that a conveying screw and a stirring screw 206 are arranged to at least partially overlap each other when seen from a horizontal direction.SOLUTION: A developer container 201 has a developing chamber, a stirring chamber 216 that forms a circulation path of developer between the developing chamber and the stirring chamber; and a partition wall 207 that partitions these chambers from each other. The partition wall has a first opening for delivering the developer from the developing chamber to the stirring chamber 216, and a second opening 207b for delivering the developer from the stirring chamber 216 to the developing chamber. A discharge port 208 is arranged outside the circulation path and discharges the developer. A developing device 200a is configured to be switchable, by a shield member 211, between an open state in which the developer can circulate through the second opening 207b closer to the discharge port 208 and a shield state in which the circulation of the developer through the second opening 207b is blocked.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present invention relates to a developing device that develops an electrostatic latent image formed on an image carrier using a developer containing toner and carrier. US20130233633A1 - Method for discharging developer from developing device - Google Patents , and , current Imagery Place Regarding. [Background technology]

[0002] Since the developer in a developing device deteriorates with use, a configuration has been proposed in which the deteriorated developer in the developing device is discharged and new developer is supplied, thereby replacing only the developer while leaving the developing device as it is (for example, Patent Document 1). In the case of the configuration described in Patent Document 1, a first chamber for supplying developer to the developing sleeve and a second chamber forming a circulation path for the developer with the first chamber are arranged above and below. Therefore, the developer is transported by transport screws respectively arranged in the first chamber and the second chamber, and the developer moves to the second chamber by gravity, and the developer can be further collected in a collection container connected to the second chamber. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-63283 A Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, from the viewpoint of recycling resources and protecting the environment, there is a demand for reusing used developing devices. Here, when collecting used developing devices, the developer may not be sealed when shipped, and if a large amount of developer remains in the used developing device, there is a risk that the developer may scatter during transportation. As a result, cleaning work when reusing the developing device becomes more complicated, and recycling costs increase.

[0005] Therefore, it is conceivable to discharge the developer by driving the conveying screw before transporting the used developing device, as in the configuration described in Patent Document 1. In the case of the configuration described in Patent Document 1, the first chamber and the second chamber are arranged vertically, so that the developer can be easily discharged by gravity.

[0006] On the other hand, there is a developing device in which the first and second chambers are arranged adjacent to each other in the horizontal or diagonal direction, but in such a configuration, the developer cannot be discharged properly by simply driving the transport screw. In other words, in a configuration in which the first transport member that transports the developer in the first chamber and the second transport member that transports the developer in the second chamber are at least partially overlapped when viewed from the horizontal direction, a sufficient amount of developer cannot be discharged even if the first transport member and the second transport member are simply driven.

[0007] The present invention relates to A developer discharge unit for discharging developer from a used developing device during a developing operation is provided. The present invention aims to provide a configuration. [Means for solving the problem]

[0008] According to one aspect of the present invention, there is provided a developing container having a developer carrier that carries and transports a developer containing a toner and a carrier to a development position, a first chamber that contains the developer to be supplied to the developer carrier, and a second chamber that is partitioned from the first chamber by a partition wall and through which the developer circulates between the first chamber and the second chamber, a first communication portion that allows the developer to communicate from the first chamber to the second chamber, a second communication portion that allows the developer to communicate from the second chamber to the first chamber, a first transport screw that is disposed in the first chamber and transports the developer in a first direction from the second communication portion toward the first communication portion, a second transport screw that transports the developer in a second direction from the first communication portion toward the second communication portion, and a transport screw that is provided in a path that continues to the second chamber downstream of the second communication portion in the second direction and for discharging the developer from the developing device. and a developer discharge section, the developer discharge method for a developing device including the developing device and comprising: an insertion step of inserting a shielding member into the second communicating section through an insertion opening of the developing container to transition from an open state in which the second communicating section is open to a shielding state in which the second communicating section is shielded; and a discharge step of discharging the developer from the developing device via the developer discharge section by rotating the first conveying screw in the same direction as the direction in which the first conveying screw is rotated during a developing operation in which an electrostatic image formed on an image carrier is developed, with the shielding member inserted into the second communicating section in the insertion step, and rotating the second conveying screw in the same direction as the direction in which the second conveying screw is rotated during the developing operation, with the shielding member inserted into the second communicating section in the insertion step. According to one aspect of the present invention, there is provided a developing container including: a developer carrier that carries and transports a developer including a toner and a carrier to a developing position; a first chamber that contains the developer to be supplied to the developer carrier; and a second chamber that is partitioned from the first chamber by a partition wall and through which the developer circulates between the first chamber and the second chamber; a first communication portion that allows the developer to communicate from the first chamber to the second chamber; a second communication portion that allows the developer to communicate from the second chamber to the first chamber; a first transport screw that is disposed in the first chamber and transports the developer in a first direction from the second communication portion toward the first communication portion; and a second transport screw that transports the developer in a second direction from the first communication portion toward the second communication portion; and a developer discharging section for discharging the developer from the developing device, the method including: an insertion step of inserting a shielding member into the first communicating section through an insertion opening of the developing container, the shielding member being adapted to transition from an open state in which the first communicating section is open to a shielding state in which the first communicating section is shielded; and a discharging step of discharging the developer from the developing device via the developer discharging section by rotating the first conveying screw in a state in which the shielding member is inserted into the first communicating section in the insertion step in the same direction as a direction in which the first conveying screw is rotated during a developing operation in which an electrostatic image formed on an image carrier is developed, and by rotating the second conveying screw in a state in which the shielding member is inserted into the first communicating section in the insertion step in the same direction as a direction in which the second conveying screw is rotated during the developing operation. and in the discharging step, during a first period, the first conveying screw is rotationally driven in the same direction at a speed slower than a driving speed of the first conveying screw when the first conveying screw is rotationally driven during the developing operation, and the second conveying screw is rotationally driven in the same direction at a speed slower than a driving speed of the second conveying screw when the second conveying screw is rotationally driven during the developing operation, and during a second period following the first period, the first conveying screw is rotationally driven in the same direction at a speed equal to the driving speed of the first conveying screw when the first conveying screw is rotationally driven during the developing operation, and the second conveying screw is rotationally driven in the same direction at a speed equal to the driving speed of the second conveying screw when the second conveying screw is rotationally driven during the developing operation. The present invention relates to a method for discharging developer from a developing device. According to one aspect of the present invention, there is provided a developing device, the developing container having a developer carrier that carries and transports a developer containing toner and a carrier to a development position, a first chamber that contains the developer to be supplied to the developer carrier, and a second chamber that is partitioned from the first chamber by a partition wall and through which the developer circulates between the first chamber and the second chamber, a first communication portion that allows the developer to communicate from the first chamber to the second chamber, a second communication portion that allows the developer to communicate from the second chamber to the first chamber, and a developer conveying portion that conveys the developer from the second chamber to the first chamber, the developer conveying portion being disposed in the first chamber and conveying the developer in a first direction from the second communication portion to the first communication portion. The developing device comprises a first transport screw for transporting developer, a second transport screw disposed in the second chamber for transporting the developer in a second direction from the first communicating portion toward the second communicating portion, and a developer discharge portion provided on a path continuing into the second chamber downstream of the second communicating portion in the second direction for discharging the developer from the developing device, wherein the developing container is provided with an insertion port for inserting a shielding member into the second communicating portion to transition from an open state that opens the second communicating portion to a shielding state that shields the second communicating portion. One aspect of the present invention is a developing device, the developing container having a developer carrier that carries and transports a developer containing toner and a carrier to a development position, a first chamber that contains the developer to be supplied to the developer carrier, and a second chamber that is partitioned from the first chamber by a partition and through which the developer circulates between the first chamber and the second chamber, a first communication portion that allows the developer to communicate from the first chamber to the second chamber, a second communication portion that allows the developer to communicate from the second chamber to the first chamber, and a developer passage that is disposed in the first chamber and flows from the second communication portion to the first communication portion. a first transport screw that transports the developer in the first direction, a second transport screw that is disposed in the second chamber and transports the developer in a second direction from the first communicating portion toward the second communicating portion, and a developer discharge portion that is provided in a path that continues to the first chamber downstream of the first communicating portion in the first direction and discharges the developer from the developing device, and the developing container is provided with an insertion port for inserting a shielding member into the first communicating portion to transition from an open state that opens the first communicating portion to a shielding state that shields the first communicating portion. the developing container has a cover that covers the first chamber and the second chamber from above, the insertion opening is provided in the cover, and the shielding member has a locking portion that is locked to an inner surface of the cover in a state in which the shielding member is inserted into the first communicating portion through the insertion opening. The developing device is characterized in that According to one aspect of the present invention, there is provided a developer discharging method for a developing device including: a developer carrier that carries and transports a developer containing a toner and a carrier to a development position; a developing container having a first chamber that contains the developer to be supplied to the developer carrier; and a second chamber that is partitioned from the first chamber by a partition wall and through which the developer circulates between the first chamber and the second chamber; a first communication portion that allows the developer to communicate from the first chamber to the second chamber; a second communication portion that allows the developer to communicate from the second chamber to the first chamber; a first transport screw that is disposed in the first chamber and transports the developer in a first direction from the second communication portion toward the first communication portion; a second transport screw that transports the developer in a second direction from the first communication portion toward the second communication portion; and a developer discharging portion that is provided in a path that continues to the second chamber downstream of the second communication portion in the second direction and discharges the developer from the developing device, and a first discharging step of discharging the developer from the developing device through the developer discharging portion by rotating the first conveying screw in a first rotational direction during a developing operation for developing an electrostatic image formed on an image carrier and rotating the second conveying screw in a second rotational direction during the developing operation while the second communicating portion is open; an inserting step of inserting a shielding member into the second communicating portion through an insertion opening of the developing container to transition from an open state in which the second communicating portion is open to a shielding state in which the second communicating portion is shielded; and a second discharging step of discharging the developer from the developing device through the developer discharging portion by rotating the first conveying screw in the first rotational direction and rotating the second conveying screw in the second rotational direction while the first communicating portion is open and while the shielding member is inserted into the second communicating portion in the inserting step. According to one aspect of the present invention, there is provided a developer discharging method for a developing device including: a developer carrier that carries and transports a developer containing a toner and a carrier to a developing position; a developing container having a first chamber that contains the developer to be supplied to the developer carrier; and a second chamber that is partitioned from the first chamber by a partition wall and through which the developer circulates between the first chamber and the second chamber; a first communication portion that allows the developer to communicate from the first chamber to the second chamber; a second communication portion that allows the developer to communicate from the second chamber to the first chamber; a first transport screw that is disposed in the first chamber and transports the developer in a first direction from the second communication portion toward the first communication portion; and a first discharge step of discharging the developer from the developing device through the developer discharge portion by, when the second communicating portion is open, rotating the first conveying screw in a first rotational direction during a developing operation for developing an electrostatic image formed on an image carrier and rotating the second conveying screw in a second rotational direction during the developing operation; an insertion step of inserting a shielding member into the first communicating portion through an insertion opening of the developing container to transition from an open state in which the first communicating portion is open to a shielding state in which the first communicating portion is shielded; and a second discharge step of, when the shielding member is inserted into the first communicating portion in the insertion step and the second communicating portion is open, rotating the first conveying screw in the first rotational direction and rotating the second conveying screw in the second rotational direction to discharge the developer from the developing device through the developer discharge portion. According to one aspect of the present invention, there is provided a developing device comprising: a developer container having a developer carrier that carries and transports a developer containing a toner and a carrier to a development position; a first chamber that contains the developer to be supplied to the developer carrier; and a second chamber that is partitioned from the first chamber by a partition wall and through which the developer circulates between the first chamber and the second chamber; a first communication portion that allows the developer to communicate from the first chamber to the second chamber; a second communication portion that allows the developer to communicate from the second chamber to the first chamber; a first transport screw that is disposed in the first chamber and transports the developer in a first direction from the second communication portion toward the first communication portion; a second transport screw that is disposed in the second chamber and transports the developer in a second direction from the first communication portion toward the second communication portion; and a developer discharge screw that is provided in a path that continues to the second chamber downstream of the second communication portion in the second direction and discharges the developer from the developing device. and a developer discharge portion, wherein, when the first communicating portion is in an open state and the second communicating portion is in an open state, the first conveying screw is rotationally driven in a first rotation direction and the second conveying screw is rotationally driven in a second rotation direction, thereby discharging the developer from the developing device via the developer discharge portion, and the developing container is provided with an insertion port for inserting a shielding member into the second communicating portion to transition from an open state in which the second communicating portion is open to a shielding state in which the second communicating portion is shielded, and when the first communicating portion is in an open state and the shielding member is inserted into the second communicating portion via the insertion port, the first conveying screw is rotationally driven in the first rotation direction and the second conveying screw is rotationally driven in the second rotation direction, thereby discharging the developer from the developing device via the developer discharge portion. According to one aspect of the present invention, there is provided a developing device comprising: a developer container having a developer carrier that carries and transports a developer containing a toner and a carrier to a developing position; a first chamber that contains the developer to be supplied to the developer carrier; and a second chamber that is partitioned from the first chamber by a partition wall and through which the developer circulates between the first chamber and the second chamber; a first communication portion that allows the developer to communicate from the first chamber to the second chamber; a second communication portion that allows the developer to communicate from the second chamber to the first chamber; a first transport screw that is disposed in the first chamber and transports the developer in a first direction from the second communication portion toward the first communication portion; a second transport screw that is disposed in the second chamber and transports the developer in a second direction from the first communication portion toward the second communication portion; and a developer discharge screw that is provided in a path that is continuous with the first chamber downstream of the first communication portion in the first direction and that discharges the developer from the developing device. and a developer discharge portion, wherein, when the first communicating portion is open and the second communicating portion is open, the first conveying screw is rotationally driven in a first rotation direction and the second conveying screw is rotationally driven in a second rotation direction, thereby discharging the developer from the developing device via the developer discharge portion, and the developing container is provided with an insertion opening for inserting a shielding member into the first communicating portion to transition from an open state in which the first communicating portion is open to a shielding state in which the first communicating portion is shielded, and when the shielding member is inserted into the first communicating portion via the insertion opening and the second communicating portion is open, the first conveying screw is rotationally driven in the first rotation direction and the second conveying screw is rotationally driven in the second rotation direction, thereby discharging the developer from the developing device via the developer discharge portion. Effect of the Invention

[0009] According to the present invention, A developer discharge portion for discharging developer from the developing device during a developing operation can be used to discharge developer from the used developing device. . [Brief description of the drawings]

[0010] [Figure 1] 1 is a schematic cross-sectional view of an image forming apparatus according to a first embodiment. [Diagram 2] FIG. 2 is a perspective view showing the developing device according to the first embodiment with the upper cover removed. [Diagram 3] FIG. 2 is a schematic cross-sectional view of the developing device according to the first embodiment. [Figure 4] FIG. 2 is a schematic vertical cross-sectional view of the developing device according to the first embodiment, taken along a horizontal line. [Diagram 5] FIG. 2 is a schematic longitudinal sectional view of the developing device according to the first embodiment, taken along a vertical direction. [Figure 6] FIG. 2 is a perspective view of a stirring screw according to the first embodiment. [Figure 7] FIG. 2 is a perspective view showing the developing device according to the first embodiment with an upper cover attached. [Figure 8] FIG. 2 is a perspective view showing the developing device according to the first embodiment in a state in which a shielding member is inserted. [Figure 9] 5 is a cross-sectional view of the periphery of a second opening in a state in which a shielding member is inserted in the developing device according to the first embodiment. FIG. [Figure 10] 6 is a graph showing the transition of the remaining amount of developer and the developer surface height when the developer is discharged in the developing device according to the first embodiment. [Figure 11] 6 is a flowchart showing a first example of a flow of a developer discharging mode according to the first embodiment. [Figure 12] FIG. 6 is a view showing a first example of a display screen when a developer discharging mode according to the first embodiment is executed. [Figure 13] 10 is a flowchart showing a second example of the flow of the developer discharging mode according to the first embodiment. [Figure 14] FIG. 11 is a view showing a second example of a display screen when the developer discharging mode according to the first embodiment is executed. [Figure 15] FIG. 11 is a cross-sectional view of the periphery of a second opening in a state in which a shielding member is inserted in a developing device according to a second embodiment. [Figure 16] FIG. 13 is a perspective view showing a state in which a shielding member is attached to an insertion opening of a developing device according to a third embodiment. [Figure 17] FIG. 11 is a perspective view showing a state in which a shielding member is peeled off from an insertion opening of a developing device according to a third embodiment. [Figure 18] 13A is a schematic cross-sectional view of a development device according to a first example of the fourth embodiment, and FIG. 13B is a schematic cross-sectional view of a development device according to a second example of the fourth embodiment. [Figure 19] FIG. 13 is a perspective view of a conveying screw according to a fifth embodiment. [Figure 20] FIG. 13 is a perspective view showing a developing device according to a sixth embodiment with an upper cover removed. [Figure 21] FIG. 13 is a schematic longitudinal sectional view of a developing device according to a sixth embodiment, taken along a vertical direction. [Figure 22] FIG. 13 is a perspective view of a conveying screw according to another example of the sixth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] <First embodiment> The first embodiment will be described with reference to Figures 1 to 14. First, a schematic configuration of an image forming apparatus according to the present embodiment will be described with reference to Figure 1.

[0012] [Image forming equipment] 1 is a cross-sectional view showing an outline of an intermediate transfer type tandem color digital printer having four image forming units as an image forming apparatus of this embodiment. Image forming apparatus 100 has first to fourth image forming units as the multiple image forming units. Each image forming unit forms an image of each color, yellow (Y), magenta (M), cyan (C), and black (K). In this embodiment, the configuration and operation of each image forming unit are substantially the same except that the color of toner used is different.

[0013] The four photosensitive drums 101a, 101b, 101c, and 101d as image carriers are cylindrical photosensitive bodies, and are rotated clockwise in FIG. 1. The surfaces of the photosensitive drums 101a to 101d are uniformly charged by charging rollers 102a, 102b, 102c, and 102d, respectively. Next, image signals of yellow, magenta, cyan, and black are input to laser scanners 103a, 103b, 103c, and 103d as exposure means, respectively. The laser scanners 103a to 103d irradiate the surfaces of the photosensitive drums 101a to 101d with laser light in accordance with the image signals, neutralize the charges, and form electrostatic latent images.

[0014] The electrostatic latent images formed on the photosensitive drums 101a to 101d are developed with a developer by the developing devices 200a, 200b, 200c, and 200d, respectively. That is, the developing devices 200a to 200d develop the electrostatic latent images into yellow, magenta, cyan, and black toner images by depositing toner charged with the same polarity as the charge polarity of the photosensitive drums 101a to 101d, respectively (reverse development).

[0015] The toner images developed on the photosensitive drums 101a to 101d are primarily transferred in order onto an intermediate transfer belt 106, which serves as an intermediate transfer body and is driven to rotate in a counterclockwise direction in FIG. 1, by primary transfer rollers 105a, 105b, 105c, and 105d. Then, the toner images are superimposed on the intermediate transfer belt 106 to form a full-color toner image. At this time, a primary transfer voltage (primary transfer bias), which is a DC voltage of a polarity opposite to the charge polarity of the toner during development, is applied to the primary transfer rollers 105a to 105d. In addition, the transfer residual toner that has not been transferred and remains on the photosensitive drums 101a to 101d is removed and collected by drum cleaners 107a, 107b, 107c, and 107d.

[0016] Meanwhile, recording material P such as paper fed from either cassette 111, 112 or manual feed tray 113 that accommodates recording material is fed toward registration roller 116 by feed roller 114 and transport roller 115. Then, the leading edge of the recording material P hits registration roller 116, which is stopped, and forms a loop, after which registration roller 116 starts to rotate in synchronization with the toner image on intermediate transfer belt 106. Then, recording material P is transported to a secondary transfer section where intermediate transfer belt 106 and secondary outer transfer roller 108 come into contact with each other. Note that examples of recording material include sheets such as paper and plastic sheets.

[0017] The toner image on the intermediate transfer belt 106 is secondarily transferred to the recording material P by the secondary transfer outer roller 108 in the secondary transfer portion. At this time, a secondary transfer voltage (secondary transfer bias) having a polarity opposite to the charge polarity of the toner at the time of development is applied to the secondary transfer outer roller 108. Thereafter, the toner image transferred onto the recording material P is fixed to the recording material P by heat and pressure in the fixing device 109, and is discharged to the outside of the machine from the discharge portion 110a or 110b. In addition, the transfer residual toner remaining on the intermediate transfer belt 106 that was not transferred in the secondary transfer portion is removed and collected by the intermediate transfer belt cleaner 117.

[0018] The image forming apparatus 100 has an operation unit 120 that allows the user to operate the image forming apparatus 100, such as starting and stopping the image forming operation of the image forming apparatus 100 and performing various settings. The operation unit 120 can display various information about the image forming apparatus 100. In this embodiment, the operation unit 120 has a touch panel 121 as a display unit, displays information on the touch panel 121, and further allows the user to perform various settings and operate the apparatus by touch operations.

[0019] [Developing device] Next, the developing devices 200a to 200d of this embodiment will be described with reference to Figs. 2 to 5. Each of the developing devices 200a to 200d is detachable from the device body 100A (Fig. 1) of the image forming device 100 so as to be replaceable. Since each of the developing devices 200a to 200d has the same configuration, the developing device 200a will be described below as a representative. Fig. 2 is a perspective view showing the inside of the developing device 200a, and Fig. 3 is a cross-sectional view taken at an approximate center position in the longitudinal direction of the developing device 200a. The longitudinal direction of the developing device 200a is a direction approximately parallel to the rotation axis direction of the photosensitive drum 101a and a developing sleeve 203 described later.

[0020] The developing device 200a of this embodiment uses a two-component developing method that uses a developer containing toner (non-magnetic) and carrier (magnetic). The two-component developing method has advantages such as stable image quality and durability of the device compared to other developing methods currently proposed. The developing device 200a contains a two-component developer in a developing container 201, and the amount of developer in this embodiment is about 250 g. The mixture ratio of toner and carrier is about 1:9 by weight. However, the amount of developer and the mixture ratio of toner and carrier should be appropriately adjusted depending on the configuration of the developing device 200a, the charge amount of the toner, the particle size of the carrier, the configuration of the image forming device 100, etc., and are not necessarily limited to these numerical values.

[0021] As shown in Fig. 3, the upper part of the developing container 201 is covered with a developing upper cover 210 as a cover, and the developing container 201 has an opening in a developing area facing the photosensitive drum 101a. In Fig. 2, the developing upper cover 210 is not shown in order to show the inside of the developing device 200a. A developing sleeve 203 as a developer carrier is rotatably installed so as to be partially exposed at the opening of the developing container 201, and a magnet 202 is non-rotatably arranged inside the developing sleeve 203.

[0022] The developing sleeve 203 is made of a non-magnetic material, and during the developing operation, while rotating, the two-component developer in the developing container 201 is carried in a layer and transported toward the developer regulating member (e.g., a blade) 204. The developer regulating member 204 is disposed opposite the surface of the developing sleeve 203 with a predetermined gap therebetween. The developer carried on the developing sleeve 203 is regulated in amount by the developer regulating member 204 to form a layer of a predetermined thickness, and then transported to the developing area. Then, the developer is supplied to the photosensitive drum 101a in the developing area to develop the electrostatic image formed on the photosensitive drum 101a. After developing the electrostatic image, the developer enters the developing container 201 as the developing sleeve 203 rotates, and is separated from the surface of the developing sleeve 203 at a peeling position and collected in the developing container 201.

[0023] The inside of the developing container 201 is divided by a partition wall 207 into a developing chamber 215 as a first chamber capable of accommodating the developing sleeve 203 and a developer, and a stirring chamber 216 as a second chamber capable of accommodating the developer. That is, the developing chamber 215 accommodates developer for supplying the developer to the developing sleeve 203. The stirring chamber 216 forms a circulation path for the developer between the developing chamber 215 and the stirring chamber 216. The partition wall 207 separates the developing chamber 215 and the stirring chamber 216. In this embodiment, the developing chamber 215 and the stirring chamber 216 are disposed so as to be adjacent to each other in the substantially horizontal direction, and the partition wall 207 is disposed between them in the substantially vertical direction.

[0024] A conveying screw 205 is disposed in the developing chamber 215 as a first conveying member, and an agitating screw 206 is disposed in the agitating chamber 216 as a second conveying member. The developer in the developing chamber 215 (inside the first chamber) is conveyed by the conveying screw 205 in the direction of the arrow A in FIG. 4, which is a first direction, and the developer in the agitating chamber 216 (inside the second chamber) is conveyed by the agitating screw 206 in the direction of the arrow B in FIG. 4, which is a second direction opposite to the first direction. The conveying screw 205 is disposed below the developing sleeve 203, and the conveying screw 205 and the agitating screw 206 are disposed at positions where they at least partially overlap when viewed from the horizontal direction. In this embodiment, the conveying screw 205 is disposed below the developing sleeve 203, and the conveying screw 205 and the agitating screw 206 are disposed adjacent to each other in the horizontal direction, at the same height, and approximately parallel to each other, and convey the developer in opposite directions while stirring it.

[0025] 4 is a cross-sectional view of the developing device 200 taken along the rotation axis of the stirring screw 206, perpendicular to the z-axis, and FIG. 5 is a cross-sectional view of the developing device 200 taken along the rotation axis of the stirring screw 206, perpendicular to the x-axis.

[0026] As shown in Figures 4 and 5, a partition wall 207 provided between the conveying screw 205 and the stirring screw 206 is formed with a first opening 207a and a second opening 207b so as to transfer the developer between the developing chamber 215 and the stirring chamber 216 and ensure smooth circulation. As the first connecting part The first opening 207a is formed on the downstream side (downstream side in the first direction) of the developer transport direction (arrow A direction) of the transport screw 205 so as to connect the developing chamber 215 and the stirring chamber 216 to each other. As the second connecting part The second opening 207b is formed on the downstream side (downstream side in the second direction) of the stirring screw 206 in the developer transport direction (arrow B direction) so as to connect the development chamber 215 and the stirring chamber 216 to each other.

[0027] The first opening 207a and the second opening 207b form a circulation path that communicates the developing chamber 215 and the stirring chamber 216 to circulate the developer. The developer in the developing container 201 is stirred and mixed by the transport screw 205 and the stirring screw 206, and is transported and circulated within the developing container 201. Specifically, the first opening 207a is an opening for transferring the developer from the developing chamber 215 to the stirring chamber 216. The second opening 207b is formed downstream of the first opening 207a in the developer transport direction of the stirring screw 206, and is an opening for transferring the developer from the stirring chamber 216 to the developing chamber 215.

[0028] The above-mentioned developing sleeve 203, conveying screw 205, and stirring screw 206 are driven by a motor 230 as a driving source (developing driving means). Specifically, the motor 230 is provided on the side of the apparatus main body 100A of the image forming apparatus 100, and when the developing device 200a is mounted in the apparatus main body 100A, the motor 230 is connected to an end of the developing device 200a, for example, the conveying screw 205, via a coupling. Then, by driving the motor 230, the developing sleeve 203, the conveying screw 205, and the stirring screw 206 are rotated. That is, a coupling connected to the motor 230 is provided at one end of the rotation axis direction of the conveying screw 205, and a gear train for transmitting the drive to the stirring screw 206 and the developing sleeve 203 is provided at the other end. Then, the driving force of the motor 230 is input to one end of the conveying screw 205, and the drive is transmitted to the developing sleeve 203 and the stirring screw 206 via the conveying screw 205 and the gear train. However, the drive transmission configuration is not limited to this, and for example, the motor 230 may be configured to input a drive force to the developing sleeve 203 or the stirring screw 206. In any case, the motor 230 is capable of driving the developing sleeve 203, the conveying screw 205, and the stirring screw 206.

[0029] Such motor 230 and developing device 200a are controlled by a control unit 240. The control unit 240 also controls the entire image forming apparatus 100, and has a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). The CPU controls each unit while reading a program corresponding to a control procedure stored in the ROM. In addition, working data and input data are stored in the RAM, and the CPU performs control by referring to the data stored in the RAM based on the above-mentioned programs, etc.

[0030] In the developing device 200a configured as described above, developer is supplied from the developing chamber 215 to the developing sleeve 203, and the developer after developing the electrostatic latent image on the photosensitive drum 101a is collected in the developing chamber 215. The developer is agitated by being circulated and transported between the developing chamber 215 and the agitation chamber 216, and the developer is supplied from the developing chamber 215 to the developing sleeve 203 again.

[0031] [Developer discharge configuration] In such a developing device, if the same developer is continuously stirred for a long time, the developer will deteriorate. Therefore, when using an image forming apparatus for a long period of time, the developing device is periodically replaced. At this time, from the viewpoint of recycling resources and protecting the environment, there is a demand to reuse used developing devices.

[0032] When a used developing device is reused, it is removed from the image forming apparatus and packed in a packaging material for transportation, but it is desirable to remove a sufficient amount of developer still contained in the developer container (for example, about 75% of the developer) before transportation. This is because when the used developing device with the developer still contained therein arrives at the remanufacturing factory, there is a possibility that the developer may leak into the packaging material during transportation, leaving the used developing device covered in developer. In addition, if the packaging material in which the used developing device is enclosed is itself transported upside down, the developer is more likely to leak out.

[0033] When a used developing device is covered in developer, the amount of cleaning work required to vacuum up the large amount of developer adhering to the used developing device at the recycling factory becomes enormous when the used developing device is reused, which leads to an increase in the cost of reused products. Therefore, in this embodiment, the used developing device is configured to be able to discharge the developer.

[0034] In the developing device 200a of this embodiment, as shown in FIG. 5, a discharge path 213 for discharging the developer is provided on the downstream side of the stirring screw 206 in the developer transport direction, continuous with a developer transport path 212 (part of a circulation path) in which the stirring screw 206 is provided. In addition, a developer discharge port 208 is provided on a bottom surface 213a of the discharge path 213. That is, the developing container 201 is disposed outside the circulation path, and has the discharge port 208 for discharging the developer. Particularly, in this embodiment, the discharge port 208 is disposed downstream of the stirring screw 206 in the developer transport direction (downstream in the second direction) from the second opening 207b of the stirring chamber 216.

[0035] As shown in the perspective view of FIG. 6, the stirring screw 206 is provided with a return blade portion 2062 as a reverse conveying portion having a conveying force in the opposite direction (arrow Hb direction) to the developer conveying direction (arrow Ha direction) on the downstream side of the developer conveying direction. That is, the stirring screw 206 is provided with a conveying blade portion 2061 having a conveying force in the developer conveying direction (arrow Ha direction). On the downstream side of the conveying blade portion 2061 in the developer conveying direction, a return blade portion 2062 having a conveying force in the opposite direction (arrow Hb direction) to the arrow Ha direction and having a smaller pitch than the conveying blade portion 2061 is provided. As shown in FIG. 5, the return blade portion 2062 is disposed downstream of the upstream end of the second opening 207b and upstream of the discharge port 208 with respect to the developer conveying direction (arrow Ha direction) of the stirring screw 206. The developer conveyed by the conveying blade portion 2061 of the stirring screw 206 is conveyed in the direction (arrow Hb direction) opposite to the developer conveying direction (arrow Ha direction) of the stirring screw 206.

[0036] Further, a discharge blade portion 2063 having a conveying force in the same direction as the arrow Ha direction is provided downstream of the return blade portion 2062 in the developer conveying direction (arrow Ha direction) of the stirring screw 206. The rotating shaft 2060 of the stirring screw 206 is rotatably provided across the developer conveying path 212 and the discharge path 213, and rotates the return blade portion 2062 and the discharge blade portion 2063 together.

[0037] During a developing operation such as image formation, the developer flowing from the developing chamber 215 to the stirring chamber 216 through the first opening 207a is transported in the direction of arrow B by the transport blade portion 2061 of the stirring screw 206. However, at the downstream position, the developer is pushed back by the return blade portion 2062 and flows from the stirring chamber 216 to the developing chamber 215 through the second opening 207b. This prevents the developer from flowing into the discharge path 213 and from being discharged from the discharge port 208. Therefore, it is not possible to discharge a sufficient amount of developer from the discharge port 208 simply by rotating the stirring screw 206. Therefore, in this embodiment, the following configuration is adopted.

[0038] [Shielding material] The developing device 200a of this embodiment is configured to be switchable between an open state in which the developer can flow through the second opening 207b, which is the opening closer to the discharge port 208, and a blocked state in which the flow of the developer through the second opening 207b is blocked by the blocking member 211. This point will be described with reference to FIGS. 7 to 9.

[0039] 7 and 8 are perspective views of the developing device 200a. As shown in FIG. 7, the developer upper cover 210 is provided with an insertion opening 210a for inserting a shielding member 211 capable of shielding the second opening 207b at a position substantially above the second opening 207b, which is closer to the discharge port 208, out of the first opening 207a and the second opening 207b. As described above, the developer upper cover 210 is a cover that covers the upper part of the developing container 201, that is, the upper part of the developing chamber 215 and the stirring chamber 216. The developer upper cover 210 is provided with an insertion opening 210a through which the shielding member 211 can be inserted.

[0040] The shielding member 211 is, for example, a sheet-like member such as a plastic sheet. When the developing device 200a is in use, such shielding member 211 is not inserted into the insertion opening 210a, and when the developing device 200a is replaced due to deterioration of the developer or the like, an operator such as a serviceman inserts the shielding member 211 into the insertion opening 210a as shown in Fig. 8. Note that when the developing device 200a is in use, it is preferable to block the insertion opening 210a with, for example, a sheet or sponge (not shown).

[0041] FIG. 9 is an enlarged view of the vicinity of the second opening 207b in a cross section cut perpendicular to the x-axis along the rotation axis of the stirring screw 206 in a state where the shielding member 211 is inserted into the insertion opening 210a. As shown in FIG. 9, the shielding member 211 is larger than the width of the second opening 207b, and is guided by the insertion opening 210a to shield the entire area of ​​the second opening 207b. In addition, it is preferable that the shielding member 211 is inserted along the surface of the partition wall 207 on the stirring screw 206 side. As will be described later, when discharging the developer in the developing container 201, the conveying screw 205 and the stirring screw 206 are driven, and at this time, the flow of the developer flowing through the second opening 207b is in a direction from the stirring chamber 216 toward the developing chamber 215. Therefore, by arranging the shielding member 211 on the stirring chamber 216 side of the partition wall 207, the shielding member 211 is pushed toward the partition wall 207 by the developer pressure of the developer on the stirring chamber 216 side. As a result, the gap between the shielding member 211 and the surface of the partition wall 207 can be tightly sealed.

[0042] In this embodiment, the insertion opening 210a is formed such that the shielding member 211 is located upstream of the flow direction of the developer flowing through the second opening 207b with respect to the partition wall 207. When the shielding member 211 is inserted into the insertion opening 210a, the shielding member 211 is arranged along the surface of the partition wall 207 on the stirring chamber 216 side. With this configuration, the flow of the developer passing through the second opening 207b can be blocked by the shielding member 211 without requiring a complex configuration.

[0043] A sealing member 210b made of a flexible material such as rubber is disposed inside the developing upper cover 210 so as to cover the insertion opening 210a. The sealing member 210b has a notch formed along the insertion opening 210a, and seals the gap with the insertion opening 210a when the shielding member 211 is inserted. This makes it possible to prevent residual developer from leaking from between the shielding member 211 and the insertion opening 210a during transportation of the used developing device 200a.

[0044] [Developer discharge mode] Next, a developer discharging mode in which developer is discharged from a used developing device using the above-mentioned configuration will be described. First, the control unit 240 of the image forming apparatus 100 can execute an image forming mode in which a normal developing operation is performed as a first mode, and a developer discharging mode as a second mode. In the image forming mode, the conveying screw 205 and the stirring screw 206 are driven in the forward direction in an open state in which the second opening 207b is not covered by the shielding member 211. In the developer discharging mode, the conveying screw 205 and the stirring screw 206 are driven in the forward direction in a shielded state in which the second opening 207b is covered by the shielding member 211. As described above, the motor 230 that drives the conveying screw 205 and the stirring screw 206 also drives the developing sleeve 203, so that the developing sleeve 203 is also driven in the image forming mode and the developer discharging mode.

[0045] That is, in the developer discharge mode, after the second opening 207b is covered by the shielding member 211, the motor 230 drives the developing sleeve 203, the conveying screw 205, and the stirring screw 206 in the same direction as during circulatory transport of the developer (in the image formation mode). At this time, the driving speed of the developing sleeve 203, the conveying screw 205, and the stirring screw 206 in the developer discharge mode is the same as the driving speed of the developing sleeve 203, the conveying screw 205, and the stirring screw 206 in the image formation mode. The time during which the developer discharge mode is executed is a predetermined time (for example, 180 seconds). That is, when a predetermined time has elapsed since the start of the developer discharge mode, the driving of the developing sleeve 203, the conveying screw 205, and the stirring screw 206 is stopped.

[0046] As a result, the developer in the developing chamber 215 is transported in the direction of arrow A in FIG. 4 by the transport screw 205, and flows into the stirring chamber 216 through the first opening 207a. Meanwhile, the flow of the developer into the developing chamber 215 is blocked because the second opening 207b in the stirring chamber 216 is blocked by the shielding member 211. Therefore, the developer in the stirring chamber 216 accumulates in the downstream portion of the developer transport direction (arrow B direction in FIG. 4) of the stirring screw 206. As a result, when the developer surface height in the downstream portion of the stirring screw 206 in the developer transport direction rises, the developer flows over the return blade portion 2062 into the discharge path 213.

[0047] The developer that has flowed into the discharge path 213 is discharged from the discharge port 208 by the discharge blade portion 2063, and is collected and stored in the recovery container 118 connected to the discharge port 208, as shown in Figures 5 and 9. The developer held on the surface of the developing sleeve 203 is peeled off as the developing sleeve 203 rotates and is collected in the developing chamber 215. When the amount of developer in the developing chamber 215 decreases, new developer cannot be pumped up to the surface of the developing sleeve 203, and the surface becomes in a state where the developer has been peeled off.

[0048] 6, in this embodiment, a configuration has been shown in which a discharge blade portion 2063 for transporting the developer in the discharge path 213 is provided downstream of the stirring screw 206 in the developer transport direction. However, this is not necessarily limited to this, and for example, when the developer is appropriately discharged from the discharge port 208 without the discharge blade portion 2063 due to the shape of the discharge path 213 or the arrangement of the discharge port 208, the discharge blade portion 2063 does not have to be provided.

[0049] 10 shows the transition of the remaining amount of developer in the developing container 201 and the developer surface height near the return blade portion 2062 when the motor 230 is driven with the second opening 207b covered by the shielding member 211. When the motor 230 is driven, the developer surface height gradually rises, and the developer is discharged and the remaining amount of developer begins to decrease (section P). After a while, the developer surface height stabilizes and the developer in the developing container 201 decreases at a substantially constant speed (section Q). Thereafter, when the developer surface height gradually begins to decrease, the rate at which the remaining amount of developer decreases also becomes gentle (section R), and after a certain amount of time has passed, the decrease in the remaining amount of developer substantially stops (section S), and the discharge is completed.

[0050] In the above description, the driving speeds of the developing sleeve 203, the conveying screw 205, and the stirring screw 206 are the same in the developer discharge mode and the image formation mode. However, the control unit 240 may control the driving speeds of the developing sleeve 203, the conveying screw 205, and the stirring screw 206 in the developer discharge mode as follows. That is, in a first period from the start of the developer discharge mode (start of driving of the motor 230), the driving speeds are made slower than those of the developing sleeve 203, the conveying screw 205, and the stirring screw 206 in the image formation mode. Then, in a second period following the first period, the driving speeds are made the same as those in the image formation mode.

[0051] First, when the developer discharge mode is executed, the amount of developer in the stirring chamber 216 is large, and if the stirring screw 206 is rotated in this state, the load becomes heavy and there is a risk of screw lock. Therefore, in the developer discharge mode, the transport screw 205 and the stirring screw 206 are rotated slowly in the first period to promote the discharge of the developer from the discharge port 208. Then, when the amount of developer in the stirring chamber 216 has decreased to a certain extent, that is, when the risk of screw lock is eliminated, the second period starts and the screw speed is set to the same as that during image formation. This allows the developer to be quickly discharged from the discharge port 208.

[0052] [First example of developer discharge mode flow] Here, a first example of the flow of the developer discharging mode will be described with reference to Figs. 11 and 12. As described above, the image forming apparatus 100 of this embodiment has a plurality of developing devices. That is, the image forming apparatus 100 has a plurality of developing devices 200a to 200d. In this example, the control unit 240 executes the developer discharging mode for a developing device selected from the plurality of developing devices 200a to 200d.

[0053] 11, for example, an operator such as a serviceman operates operation unit 120 (FIG. 1) to cause image forming apparatus 100 to transition to a service mode (S1). Note that the service mode is a special mode for performing maintenance on image forming apparatus 100. Then, on a service mode screen displayed on touch panel 121 of operation unit 120, a button for executing a developer discharge mode is pressed (S2).

[0054] 12 is displayed on touch panel 121 of operation unit 120, which also serves as a selection unit. The operator selects the developing device (cartridge) for which the developer discharge mode is to be executed by touching the color of the developing device (cartridge) for which the operator wants to execute the developer discharge mode (S3). Control unit 240 executes the developer discharge mode described above for the touched developing device (S4).

[0055] Before executing the developer discharge mode, the shielding member 211 is inserted into the developing device for which the developer discharge mode is to be executed. The timing for inserting the shielding member 211 may be before executing the developer discharge mode. For example, the shielding member 211 may be inserted before or after the transition to the service mode, when the button for executing the developer discharge mode is pressed, or when the developing device for which the developer discharge mode is to be executed is selected. Also, for example, when the developing device for which the developer discharge mode is to be executed is selected, a message indicating that the shielding member 211 is to be inserted into the selected developing device is displayed on the touch panel 121. Then, after inserting the shielding member 211, the developing device may be mounted in the apparatus main body 100A to execute the developer discharge mode. Also, at this time, a confirmation button may be displayed and the developer discharge mode may be executed by pressing the confirmation button.

[0056] [Second example of developer discharge mode flow] Next, a second example of the flow of the developer discharge mode described above will be described with reference to FIG. 13 and FIG. 14. In this example, when the value related to the life of the developing device reaches a predetermined threshold, the operation unit 120 displays that fact and whether or not the developer discharge mode is to be executed, and when execution of the developer discharge mode is selected, the developer discharge mode is executed. Whether or not the developing device has reached its life may be determined, for example, by counting the number of sheets of recording material used for each developing device, and when the counted number of sheets reaches a predetermined threshold, the control unit 240 may determine that the developing device has reached its life. Also, whether or not the developing device has reached its life may be determined, for example, by counting the number of rotations of the developing sleeve 203 for each developing device, and when the counted number of rotations reaches a predetermined threshold, the control unit 240 may determine that the developing device has reached its life.

[0057] Specifically, as shown in Fig. 13, the control unit 240 determines whether the developing device has reached the end of its life (S11). If it is determined that the developing device (developing cartridge) has reached the end of its life (YES in S11), a screen shown in Fig. 14 is displayed on the touch panel 121 of the operation unit 120. Then, when the operator presses the developer discharge mode execution button ("YES" in Fig. 14) (YES in S12), the control unit 240 executes the developer discharge mode (S13).

[0058] In this example, when it is determined that a developing device has reached the end of its life (YES in S11), a screen such as that shown in FIG. 12 may be displayed on touch panel 121. In this case, the color of the developing device displayed on touch panel 121 is displayed so that it is clear which developing device control unit 240 has determined to have reached its life. For example, only developing devices that have reached their life may be displayed, or developing devices that have reached their life may be displayed separately from developing devices that have not, so that only developing devices that have reached their life may be selectable. Then, when a developing device is selected on touch panel 121, it may be determined that the "developer discharge mode execution button has been pressed" in S12.

[0059] In this manner, in this embodiment, the transport screw 205 and the stirring screw 206 are driven in a state in which the second opening 207b close to the discharge port 208 is covered by the shielding member 211, thereby discharging the developer in the developing container 201 from the discharge port 208. For this reason, even in a configuration in which the transport screw 205 and the stirring screw 206 are arranged so as to overlap at least partially when viewed from the horizontal direction, the developer can be appropriately discharged.

[0060] That is, even in the developing device 200a in which the developing chamber 215 and the stirring chamber 216 in which the developer circulates are arranged in a substantially horizontal direction, the developer can be discharged by blocking the second opening 207b, which is closer to the discharge port 208, of the two openings provided at both ends of the partition wall 207. This makes it possible to suppress scattering of the developer during transportation associated with recovery of the developing device, and to reduce the cleaning cost during recycling.

[0061] <Second embodiment> The second embodiment will be described with reference to Fig. 15. In this embodiment, the shielding member 211a is made difficult to fall out when inserted into the insertion port 210a. Since the other configurations and functions are the same as those of the first embodiment described above, the same configurations are given the same reference numerals and explanations and illustrations are omitted or simplified, and the following description will focus on the points that are different from the first embodiment.

[0062] Even when the developer discharge mode is executed and the discharge of the developer is completed, a small amount of developer may remain near the return blade portion 2062 of the stirring screw 206. For this reason, when the developing device 200a is collected, it is desirable to leave the shielding member 211a inserted in the insertion port 210a so that the residual developer does not scatter to the outside of the developing device 200a through the second opening 207b. In addition, there is a risk that the shielding member 211a may unintentionally fall off due to vibrations or the like during the transportation of the collected developing device 200a.

[0063] Therefore, in this embodiment, as shown in Fig. 15, a return shape 211b is provided as an engagement portion at the end of the shielding member 211a. After the shielding member 211a is inserted into the insertion opening 210a, the return shape 211b is hooked on the inner edge of the insertion opening 210a to prevent it from coming off. That is, the shielding member 211a in this embodiment has the return shape 211b as an engagement portion that engages with the inner surface of the developing upper cover 210 (in this embodiment, the sealing member 210b arranged on the inner surface) when inserted into the insertion opening 210a.

[0064] The return shape 211b is formed so as to protrude outward in the width direction at both ends of the shielding member 211a in the width direction, and further, the end on the downstream side in the insertion direction is formed so as to have an inclined surface that inclines inward in the width direction toward the downstream. In addition, the upstream end of the return shape 211b in the insertion direction is formed in a straight line shape that is approximately parallel to the inner surface of the developer upper cover 210. As a result, when the shielding member 211a is inserted into the insertion opening 210a, the return shape 211b elastically deforms while the inclined surface of the return shape 211b acts as a guide, and the shielding member 211a is inserted into the insertion opening 210a. Then, after insertion, the return shape 211b elastically restores its original shape, and the straight line portion engages with the inner surface of the developer upper cover 210, making it difficult for the shielding member 211a to come out of the insertion opening 210a.

[0065] In the case of this embodiment, since the shielding member 211a is difficult to come out after being inserted into the insertion opening 210a, leakage of developer during transportation of a used developing device can be further suppressed.

[0066] <Third embodiment> The third embodiment will be described with reference to Figures 16 and 17. In this embodiment, the shielding member 211c is configured to be arranged so as to block the insertion opening 210a when not inserted into the insertion opening 210a. Since the other configurations and functions are the same as those of the first embodiment described above, the same configurations are given the same reference numerals, and explanations and illustrations are omitted or simplified, and the following description will focus on the points that are different from the first embodiment.

[0067] At the time of initial shipment of the developing device 200a, a part of the space inside the developing container 201 is sealed with a sheet material or the like, and an initial developer is filled in with a high filling rate. In such a configuration, when the insertion opening 210a constitutes a part of the sealed space, the sealing member 210b having the above-mentioned notch may not provide sufficient sealing. In such a case, a separate insertion opening cover member for covering the insertion opening 210a may be provided. However, providing a separate insertion opening cover increases the number of parts.

[0068] Therefore, in this embodiment, as shown in Fig. 16, a shielding member 211c is removably attached to the developer upper cover 210 so as to cover the insertion opening 210a. When replacing a used developing device 200a, as shown in Fig. 17, the shielding member 211c is peeled off from the developer upper cover 210 to expose the insertion opening 210a, and the peeled shielding member 211c is inserted into the insertion opening 210a as shown in Fig. 9. That is, the shielding member 211c in this embodiment is attached to the outer surface of the developer upper cover 210 so as to block the insertion opening 210a when not inserted into the insertion opening 210a, and is peeled off from the outer surface of the developer upper cover 210 when inserted into the insertion opening 210a.

[0069] With this configuration, when the developing device 200a is initially shipped, the insertion opening 210a is covered by the shielding member 211c, so that leakage of the initial developer from the insertion opening 210a can be suppressed. On the other hand, when replacing a used developing device 200a, the shielding member 211c is peeled off and inserted into the insertion opening 210a to shield the second opening 207b, and the developer discharge mode as described above can be executed.

[0070] The shielding member 211c may be cut along a perforation to expose the insertion opening 210a, and the cut shielding member 211c may be inserted into the insertion opening 210a. The shielding member may have a shape similar to that of the second embodiment.

[0071] <Fourth embodiment> The fourth embodiment will be described with reference to Figures 18(a) and (b). In the above-mentioned embodiments, the conveying screw 205 is disposed below the developing sleeve 203, and the developing chamber 215 and the stirring chamber 216 are disposed in a substantially horizontal direction, but the present invention is also applicable to an arrangement in which the heights of the developing chamber 215 and the stirring chamber 216 are different. In this embodiment, two examples of a configuration in which the heights of the developing chamber 215 and the stirring chamber 216 are different will be described. Since the other configurations and functions are the same as at least one of the above-mentioned first to third embodiments, the same reference numerals will be used for the same configurations, and explanations and illustrations will be omitted or simplified, and the following description will focus on the points that are different from the first embodiment.

[0072] First, in the case of the configuration of the first example of this embodiment shown in Fig. 18(a), the position of the bottom surface of the stirring chamber 216 is higher than the position of the bottom surface of the developing chamber 215 on the downstream side of the stirring screw 206 in the developer transport direction of the stirring chamber 216 provided with the discharge port 208. That is, the stirring screw 206 and the stirring chamber 216 are configured to be higher toward the downstream side of the stirring screw 206 in the developer transport direction. In this configuration as well, the transport screw 205 is disposed below the developing sleeve 203. Moreover, in this configuration as well, the developing chamber 215 and the stirring chamber 216 are disposed adjacent to each other in the horizontal direction, and the transport screw 205 and the stirring screw 206 are disposed so as to overlap at least partially when viewed in the horizontal direction.

[0073] In this example, at the second opening 207b closer to the discharge port 208, the developer flows from the stirring chamber 216 into the developing chamber 215 due to the effect of gravity. However, by closing the second opening 207b in the developer discharge mode, the developer can be blocked from flowing from the stirring chamber 216 into the developing chamber 215 and discharged. Note that the same applies even if the transport screw 205 and the stirring screw 206 are arranged in parallel, the upper end of the outer diameter of the stirring screw 206 is higher than the upper end of the outer diameter of the transport screw 205, and further the position of the bottom surface of the stirring chamber 216 is higher than the position of the bottom surface of the developing chamber 215.

[0074] Next, in the case of the configuration of the second example of this embodiment shown in Fig. 18(b), the position of the bottom surface of the stirring chamber 216, in which the discharge port 208 is provided, is configured to be lower than the position of the bottom surface of the development chamber 215, on the downstream side in the developer transport direction of the stirring screw 206. That is, the stirring screw 206 and the stirring chamber 216 are configured to be lower toward the downstream side in the developer transport direction of the stirring screw 206. In this configuration as well, the transport screw 205 is disposed below the development sleeve 203. Moreover, in this configuration as well, the development chamber 215 and the stirring chamber 216 are disposed adjacent to each other in the horizontal direction, and the transport screw 205 and the stirring screw 206 are disposed so as to at least partially overlap each other when viewed in the horizontal direction.

[0075] In this example, even if the stirring chamber 216 is lower than the developing chamber 215 as described above, if the lower end 2071b of the second opening 207b close to the discharge port 208 is positioned below the upper end of the outer diameter of the stirring screw 206, the developer flows from the stirring chamber 216 to the developing chamber 215 at the second opening 207b. However, even in this example, the developer can be discharged by blocking the inflow of the developer from the stirring chamber 216 to the developing chamber 215 by blocking the second opening 207b in the developer discharge mode. Note that the same applies even if the conveying screw 205 and the stirring screw 206 are arranged in parallel, the upper end of the outer diameter of the stirring screw 206 is lower than the upper end of the outer diameter of the conveying screw 205, and further, the position of the bottom surface of the stirring chamber 216 is lower than the position of the bottom surface of the developing chamber 215.

[0076] <Fifth embodiment> The fifth embodiment will be described with reference to the above-mentioned drawings and with reference to Fig. 19. In this embodiment, the discharge port 208 is provided on the downstream side of the developer transport direction (downstream side in the first direction) of the transport screw 205 of the developing chamber 215. Since the other configurations and functions are the same as those of the first embodiment described above, the same configurations are given the same reference numerals and explanations and illustrations are omitted or simplified, and the following description will focus on the points that are different from the first embodiment.

[0077] In the present embodiment, as described above, the discharge port 208 is provided downstream of the first opening 207a of the developing chamber 215. For this reason, as shown in FIG. 19, a return blade portion 2052 having a conveying force in the opposite direction (arrow Kb direction) to the developer conveying direction (arrow Ka direction) is provided on the downstream side of the conveying screw 205 in the developer conveying direction. The conveying screw 205 includes a conveying blade portion 2051 having a conveying force in the developer conveying direction (arrow Ka direction). On the downstream side of the conveying blade portion 2051 in the developer conveying direction, a return blade portion 2052 having a conveying force in the opposite direction (arrow Kb direction) to the arrow Ka direction and having a smaller pitch than the conveying blade portion 2051 is provided. The return blade portion 2052 is disposed downstream of the upstream end of the first opening 207a and upstream of the discharge port 208 with respect to the developer conveying direction (arrow Ka direction) of the conveying screw 205. The developer conveyed by the conveying blade portion 2051 of the conveying screw 205 is conveyed in the direction (arrow Kb direction) opposite to the developer conveying direction (arrow Ka direction) of the conveying screw 205.

[0078] Further, downstream of the return blade portion 2052 in the developer transport direction (arrow Ka direction) of the transport screw 205, a discharge blade portion 2053 having a transport force in the same direction as the arrow Ka direction is provided. The rotating shaft 2050 of the transport screw 205 is rotatably provided across the developer transport path and discharge path, and rotates the return blade portion 2052 and the discharge blade portion 2053 together.

[0079] When the developer discharge mode is executed, the first opening 207a closer to the discharge port 208 is covered by the shielding member 211. That is, in the case of the present embodiment, the opening that can be switched between an open state and a covered state by the shielding member 211 is the first opening 207a. For this reason, the insertion opening 210a of the shielding member 211 is disposed substantially above the first opening 207a.

[0080] Further, the insertion opening 210a is formed so that the shielding member 211 is located upstream of the flow direction of the developer flowing through the first opening 207a with respect to the partition 207. Then, when the shielding member 211 is inserted into the insertion opening 210a, the shielding member 211 is arranged along the surface of the partition 207 on the developing chamber 215 side. This allows the shielding member 211 to block the flow of the developer passing through the first opening 207a without requiring a complex configuration.

[0081] In this embodiment, too, the discharge blade portion 2053 may be omitted if the developer is appropriately discharged from the discharge port 208 due to the shape of the discharge path and the arrangement of the discharge port 208. Also, in this embodiment, the configurations of the above-described embodiments are applicable.

[0082] Sixth embodiment The sixth embodiment will be described with reference to the above-mentioned figures and with reference to Figures 20 to 22. In this embodiment, the present invention is applied to a developing device employing an automatic developer replacement method described below, and deteriorated developer can be discharged from a discharge port 208 used for automatic developer replacement. Since the other configurations and functions are the same as those of the first embodiment described above, the same configurations are denoted with the same reference numerals, and explanations and illustrations are omitted or simplified, and the following description will focus on the points that are different from the first embodiment.

[0083] [Automatic developer replacement system] In a two-component developing device, deterioration of the developer, especially the carrier, due to long-term continuous use is inevitable, so there is a configuration that employs an automatic developer replacement system aimed at extending the life of the developing device. This configuration will be explained using Figures 20 and 21. Figure 20 is a perspective view showing the inside of a developing device 200A in this embodiment, and Figure 21 is a cross-sectional view of developing device 200A cut perpendicular to the x-axis along the rotation axis of stirring screw 206.

[0084] In the automatic developer replacement system, in addition to the toner consumed by the developing operation of the developing device 200A, supply developer containing a small amount of carrier is supplied to the developing device 200A from a developer supply unit 119, and excess developer in the developing device 200A is discharged to an external collection container 118. In this embodiment, the carrier contained in the supply developer is about 10% by weight. However, the mixture ratio of the carrier should be appropriately adjusted depending on the configuration of the developing device 200A, the ease of deterioration of the developer, the configuration of the image forming apparatus, etc., and is not necessarily limited to this numerical value.

[0085] In the automatic developer replacement system, the surplus developer is discharged almost simultaneously with the supply of the replenishment developer, so that the characteristics of the developer as a whole can be stabilized for a long period of time without causing the image forming apparatus to become larger or the cost to rise. In addition, the developer is replaced automatically in accordance with the image formation, so that the frequency of the work of replacing the developer or the developing device can be reduced, which contributes to the reduction of the running cost.

[0086] 20, in this embodiment, developer supply unit 119 supplies supply developer from developer supply port 217 provided on the upstream side of mixing screw 206 in mixing chamber 216 in the developer transport direction. The toner contained in the supply developer is consumed by image formation, but the carrier supplied together with the toner is not consumed and remains in developing container 201. For this reason, if supply developer is continuously supplied so as to keep the toner concentration of the developer in developing container 201 constant, the amount of developer in developing container 201 increases as images are formed.

[0087] 21, in the present embodiment, a discharge path 213 for discharging developer is provided downstream of the stirring screw 206 in the developer transport direction, continuous with the developer transport path 212 in which the stirring screw 206 is provided. A discharge port 208 is provided in the discharge path 213. The stirring screw 206 is provided with a return blade portion 2062 and a discharge blade portion 2063, and the rotating shaft 2060 of the stirring screw 206 rotates the return blade portion 2062 and the discharge blade portion 2063 together.

[0088] When the amount of developer in the developing container 201 increases due to repeated replenishment of the replenishment developer, the excess developer in the stirring chamber 216 passes over the return blade portion 2062 and enters the discharge path 213. The excess developer is then transported by the discharge blade portion 2063 in the discharge path 213 to the discharge port 208 and discharged. The developer discharged through the discharge port 208 is collected and stored in the recovery container 118.

[0089] As described above, in the automatic developer replacement method, carrier is replenished as a replenishment developer together with toner, and the amount of developer in the developing container 201 is kept constant while the excess developer is discharged, so that the developer is automatically and gradually replaced.

[0090] [Developer discharge mode using discharge port for automatic developer replacement] As described above, even in developing device 200A employing an automatic developer replacement system, there are cases where replacement is required due to deterioration of developer or durability deterioration of other components, etc. In such a case, a procedure for discharging developer using discharge port 208 for automatic developer replacement without providing a new discharge port for discharging developer, and the operation of developing device 200A will be described.

[0091] As in the first embodiment, the developer upper cover 210 is provided with an insertion opening 210a and a sealing member 210b, and the second opening 207b closer to the discharge opening 208 can be blocked by a blocking member 211. When executing the developer discharge mode, after the second opening 207b is blocked by the blocking member 211, the transport screw 205 and the stirring screw 206 are driven in a state where the supply of the supply developer from the developer supply unit 119 to the developing device 200A is stopped. For example, the transport screw 205 and the stirring screw 206 are driven to rotate in the same forward direction as in the image formation mode, in a state where the screw for supplying the developer provided in the developer supply unit 119 is stopped.

[0092] As described above, during image formation, only the surplus developer, which has increased due to replenishment, passes over the return blade portion 2062 and is discharged. On the other hand, when the second opening 207b is blocked by the shielding member 211, the developer is prevented from flowing from the stirring chamber 216 into the developing chamber 215, and the developer accumulates in the downstream portion of the stirring screw 206. As a result, when the developer surface height in the downstream portion of the stirring screw 206 rises, the developer passes over the return blade portion 2062 and flows from the transport path 212 into the discharge path 213. The developer that has flowed into the discharge path 213 is discharged from the discharge port 208 by the discharge blade portion 2063, and is collected and stored in the collection container 118.

[0093] Also, as in the first embodiment, when the developing sleeve 203 is rotated in the developer discharge mode, the developer held on the surface is collected into the developing chamber 215, while the developer in the developing chamber 215 decreases, so that new developer cannot be pumped up. Therefore, the developer held on the surface of the developing sleeve 203 can also be peeled off and discharged.

[0094] As described above, even in the developing device 200A employing the automatic developer replacement method, the developer can be discharged by utilizing the discharge port 208 for automatic developer replacement. That is, in the case of this embodiment as well, when the developer discharge mode is executed, the developer in the developing container 201 can be sufficiently discharged by covering the second opening 207b closer to the discharge port with the shielding member 211.

[0095] In this embodiment, too, if the developer is appropriately discharged from the discharge port 208 due to the shape of the discharge path 213 and the arrangement of the discharge port 208, the discharge blade portion 2063 may be omitted.

[0096] In the above-described developing device 200A, the developer supply port 217 is provided on the upstream side of the stirring screw 206 in the developer transport direction in the stirring chamber 216. However, the developer supply port may be provided at a position after the developer collected from the developing sleeve 203 into the developing container 201 as the developing sleeve 203 rotates after the electrostatic latent image is developed and joins the circulation path, for example, on the downstream side of the developing chamber 215 in the developer transport direction. In this case, as shown in FIG. 22, a return blade portion 2052 having a transport force in the opposite direction (arrow Kb direction) to the developer transport direction (arrow Ka direction) is provided on the downstream side of the transport screw 205A in the developer transport direction. The supply developer is transported into the circulation path of the developing container 201 by the return blade portion 2052.

[0097] In the present embodiment, the discharge path 213 for discharging excess developer and the discharge port 208 are provided on the downstream side of the developer transport direction of the stirring screw 206. However, as in the fifth embodiment, these may be provided on the downstream side of the developer transport direction of the developing chamber 215. In this case, as shown in FIG. 19, a return blade portion 2052 having a transport force in the opposite direction (arrow Kb direction) to the developer transport direction (arrow Ka direction) is provided on the downstream side of the transport screw 205 in the developer transport direction.

[0098] When the supply of the supply developer is repeated, the excess developer passes over the return blade portion 2052 on the downstream side of the developing chamber 215 and enters the discharge path 213, and is discharged from the discharge port 208. In this way, the replacement of the developer is automatically and gradually performed.

[0099] In addition, when the discharge path 213 is provided downstream of the developing chamber 215 in the developer transport direction, it is desirable to provide the developer supply port 217 upstream of the stirring screw 206 in the stirring chamber 216 in the developer transport direction as in FIG. 21. This is because the developer in the developing container 201 and the newly replenished replenishment developer can be sufficiently mixed until the developer is pumped up to the surface of the developing sleeve 203. In a developing device of an automatic developer replacement type having such a configuration, in order to discharge the developer during replacement, the first opening 207a closer to the discharge port 208 is shielded by a shielding member 211. Therefore, the insertion port 210a of the shielding member 211 may be located substantially above the first opening 207a. The rest is the same as in the fifth embodiment.

[0100] <Other embodiments> In each of the above-described embodiments, a configuration has been described in which the developer is supplied to the developing sleeve 203 in the developing chamber 215 as the first chamber, and the developer is collected from the developing sleeve 203. However, the present invention is also applicable to a so-called function-separated developing device in which the developer is supplied to the developing sleeve 203 in the developing chamber 215 as the first chamber, and the developer is collected from the developing sleeve 203 in the stirring chamber 216 as the second chamber.

[0101] Furthermore, the present invention is not limited to the tandem type image forming apparatus 1 using the intermediate transfer method, but may be an image forming apparatus of another method. Also, the present invention is not limited to full color, but may be monochrome or monocolor. Alternatively, the present invention may be embodied in various applications such as printers, various printing machines, copiers, FAX machines, and multifunction machines. [Explanation of symbols]

[0102] 100 Image forming apparatus 101a, 101b, 101c, 101d: photosensitive drum (image carrier) 120... Operation section (selection section) 200a, 200b, 200c, 200d, 200A...Developing device 201...Developing container 203 Developing sleeve (developer carrier) 205, 205A···Conveying screw (first conveying member) 2051···Return screw (reverse conveying section) 206: Agitating screw (second conveying member) 2061···Reverse screw (reverse conveying section) 207...Bulkhead 207a...1st opening 207b...Second opening 208...Discharge port 210···Developing top cover (cover) 210a···Insertion port 211, 211a, 211c... Shielding members 211b... Return shape (locking part) 215...Development chamber (1st chamber) 216... Stirring chamber (2nd chamber) 230 Motor (drive source) 240...Control section

Claims

1. a developer carrying member that carries and carries a developer containing a toner and a carrier to a development position; a developing container having a first chamber that contains the developer to be supplied to the developer carrying member; and a second chamber that is partitioned from the first chamber by a partition wall and through which the developer circulates between the first chamber and the second chamber; a first communication portion that allows the developer to communicate from the first chamber to the second chamber; a second communication portion that allows the developer to communicate from the second chamber to the first chamber; a first conveying screw that is disposed in the first chamber and conveys the developer in a first direction from the second communication portion toward the first communication portion; a second conveying screw that conveys the developer in a second direction from the first communication portion toward the second communication portion; and a developer discharging portion that is provided in a path that continues to the second chamber downstream of the second communication portion in the second direction and discharges the developer from the developing device, an insertion step of inserting a shielding member into the second communication portion through an insertion opening of the developing container to transition from an open state in which the second communication portion is opened to a shielding state in which the second communication portion is shielded; in the inserting step, with the shielding member inserted into the second communicating portion, the first conveying screw is rotationally driven in the same direction as a direction in which the first conveying screw is rotationally driven during a developing operation for developing an electrostatic image formed on an image carrier, and, In the inserting step, with the shielding member inserted into the second communication portion, the second conveying screw is rotationally driven in the same direction as the direction in which the second conveying screw is rotationally driven during the developing operation, and discharging the developer from the developing device through the developer discharging portion. A method for discharging developer from a developing device.

2. In the discharging step, the first conveying screw is rotationally driven in the same direction at the same speed as a driving speed of the first conveying screw when the first conveying screw is rotationally driven during the developing operation; and, The second conveying screw is rotated at the same speed and in the same direction as the driving speed of the second conveying screw when the second conveying screw is rotated during the developing operation.

2. A method for discharging developer from a developing device according to claim 1.

3. In the discharging step, In the first period, the first conveying screw is rotationally driven in the same direction at a speed slower than a driving speed of the first conveying screw when the first conveying screw is rotationally driven during the developing operation, and the second conveying screw is rotationally driven in the same direction at a speed slower than a driving speed of the second conveying screw when the second conveying screw is rotationally driven during the developing operation; and, In a second period following the first period, The first conveying screw is rotationally driven in the same direction at a driving speed that is the same as the driving speed of the first conveying screw when the first conveying screw is rotationally driven during the developing operation, and the second conveying screw is rotationally driven in the same direction at a driving speed that is the same as the driving speed of the second conveying screw when the second conveying screw is rotationally driven during the developing operation.

2. The method for discharging developer from a developing device according to claim 1.

4. a developer carrying member that carries and carries a developer containing a toner and a carrier to a development position; a developing container having a first chamber that contains the developer to be supplied to the developer carrying member; and a second chamber that is partitioned from the first chamber by a partition wall and through which the developer circulates between the first chamber and the second chamber; a first communication portion that allows the developer to communicate from the first chamber to the second chamber; a second communication portion that allows the developer to communicate from the second chamber to the first chamber; a first conveying screw that is disposed in the first chamber and conveys the developer in a first direction from the second communication portion toward the first communication portion; a second conveying screw that conveys the developer in a second direction from the first communication portion toward the second communication portion; and a developer discharging portion that is provided in a path that is continuous with the first chamber downstream of the first communication portion in the first direction and that discharges the developer from the developing device, an insertion step of inserting a shielding member into the first communication portion through an insertion opening of the developing container to transition from an open state in which the first communication portion is opened to a shielding state in which the first communication portion is shielded; in the inserting step, with the shielding member inserted into the first communicating portion, the first conveying screw is rotationally driven in the same direction as a direction in which the first conveying screw is rotationally driven during a developing operation for developing an electrostatic image formed on an image carrier, and, In the inserting step, with the shielding member inserted into the first communicating portion, the second conveying screw is rotationally driven in the same direction as the direction in which the second conveying screw is rotationally driven during the developing operation, a discharging step of discharging the developer from the developing device through the developer discharging portion; having In the discharging step, In the first period, the first conveying screw is rotationally driven in the same direction at a speed slower than a driving speed of the first conveying screw when the first conveying screw is rotationally driven during the developing operation, and the second conveying screw is rotationally driven in the same direction at a speed slower than a driving speed of the second conveying screw when the second conveying screw is rotationally driven during the developing operation; and, In a second period following the first period, The first conveying screw is rotationally driven in the same direction at a driving speed that is the same as the driving speed of the first conveying screw when the first conveying screw is rotationally driven during the developing operation, and the second conveying screw is rotationally driven in the same direction at a driving speed that is the same as the driving speed of the second conveying screw when the second conveying screw is rotationally driven during the developing operation. A method for discharging developer from a developing device.

5. 1. A developing device comprising: a developer carrier that carries and transports a developer containing a toner and a carrier to a development position; a developing container including a first chamber for accommodating the developer to be supplied to the developer carrier, and a second chamber partitioned from the first chamber by a partition wall and through which the developer circulates between the first chamber and a second chamber; a first communication portion that allows the developer to communicate from the first chamber to the second chamber; a second communication portion that allows the developer to communicate from the second chamber to the first chamber; a first conveying screw disposed in the first chamber and configured to convey the developer in a first direction from the second communicating portion toward the first communicating portion; a second conveying screw disposed in the second chamber and configured to convey the developer in a second direction from the first communicating portion toward the second communicating portion; a developer discharge portion that is provided in a path continuing to the second chamber downstream of the second communication portion in the second direction and that discharges the developer from the developing device, The developing container is provided with an insertion opening for inserting a shielding member into the second communicating portion to transition from an open state in which the second communicating portion is opened to a shielding state in which the second communicating portion is shielded. A developing device characterized by the above.

6. the developing container has a cover covering an upper portion of each of the first chamber and the second chamber, The insertion opening is provided in the cover.

6. The developing device according to claim 5,

7. The shielding member has a locking portion that is locked to the inner surface of the cover when the shielding member is inserted into the second communication portion through the insertion opening.

7. The developing device according to claim 6.

8. 1. A developing device comprising: a developer carrier that carries and transports a developer containing a toner and a carrier to a development position; a developing container including a first chamber for accommodating the developer to be supplied to the developer carrier, and a second chamber partitioned from the first chamber by a partition wall and through which the developer circulates between the first chamber and a second chamber; a first communication portion that allows the developer to communicate from the first chamber to the second chamber; a second communication portion that allows the developer to communicate from the second chamber to the first chamber; a first conveying screw disposed in the first chamber and configured to convey the developer in a first direction from the second communicating portion toward the first communicating portion; a second conveying screw disposed in the second chamber and configured to convey the developer in a second direction from the first communicating portion toward the second communicating portion; a developer discharge portion that is provided in a path continuing to the first chamber downstream of the first communication portion in the first direction and that discharges the developer from the developing device, the developing container is provided with an insertion opening for inserting a shielding member into the first communicating portion to transition from an open state in which the first communicating portion is opened to a shielding state in which the first communicating portion is shielded, the developing container has a cover covering an upper portion of each of the first chamber and the second chamber, The insertion opening is provided in the cover, The shielding member has a locking portion that is locked to the inner surface of the cover when the shielding member is inserted into the first communication portion through the insertion opening. A developing device characterized by the above.

9. A method for discharging developer from a developing device, comprising: a developer carrier which carries and transports developer containing toner and a carrier to a developing position; a developing container having a first chamber which contains the developer to be supplied to the developer carrier; and a second chamber which is partitioned from the first chamber by a partition and through which the developer circulates between the first chamber and the second chamber; a first communication portion which allows the developer to communicate from the first chamber to the second chamber; a second communication portion which allows the developer to communicate from the second chamber to the first chamber; a first transport screw which is disposed in the first chamber and transports the developer in a first direction from the second communication portion toward the first communication portion; a second transport screw which transports the developer in a second direction from the first communication portion toward the second communication portion; and a developer discharge portion which is provided in a path which continues to the second chamber downstream of the second communication portion in the second direction and which discharges the developer from the developing device, a first discharging step of discharging the developer from the developing device via the developer discharging portion by rotating the first conveying screw in a first rotation direction during a developing operation for developing an electrostatic image formed on an image carrier, while the first communicating portion is in an open state and the second communicating portion is in an open state, and by rotating the second conveying screw in a second rotation direction during the developing operation; an insertion step of inserting a shielding member into the second communication portion through an insertion opening of the developing container to transition from an open state in which the second communication portion is opened to a shielding state in which the second communication portion is shielded; a second discharging step of discharging the developer from the developing device via the developer discharging portion by rotating the first conveying screw in the first rotation direction and rotating the second conveying screw in the second rotation direction in a state in which the first communication portion is opened and the shielding member is inserted into the second communication portion in the inserting step; 13. A method for discharging developer from a developing device, comprising:

10. In the second discharge step, The first conveying screw is rotationally driven in the first rotation direction at a speed equal to a driving speed of the first conveying screw when the first conveying screw is rotationally driven in the first rotation direction during the developing operation, and the second conveying screw is rotationally driven in the second rotation direction at a speed equal to a driving speed of the second conveying screw when the second conveying screw is rotationally driven in the second rotation direction during the developing operation.

10. The method for discharging developer from a developing device according to claim 9.

11. In the second discharge step, In the first period, the first conveying screw is rotationally driven in the first rotation direction at a speed slower than a driving speed of the first conveying screw when the first conveying screw is rotationally driven in the first rotation direction during the developing operation, and the second conveying screw is rotationally driven in the second rotation direction at a speed slower than a driving speed of the second conveying screw when the second conveying screw is rotationally driven in the second rotation direction during the developing operation; and, In a second period following the first period, The first conveying screw is rotationally driven in the first rotation direction at a speed equal to a driving speed of the first conveying screw when the first conveying screw is rotationally driven in the first rotation direction during the developing operation, and the second conveying screw is rotationally driven in the second rotation direction at a speed equal to a driving speed of the second conveying screw when the second conveying screw is rotationally driven in the second rotation direction during the developing operation.

10. The method for discharging developer from a developing device according to claim 9.

12. A method for discharging developer from a developing device, comprising: a developer carrier which carries and transports developer containing toner and a carrier to a developing position; a developing container having a first chamber which contains the developer to be supplied to the developer carrier; and a second chamber which is partitioned from the first chamber by a partition and through which the developer circulates between the first chamber and the second chamber; a first communication portion which allows the developer to communicate from the first chamber to the second chamber; a second communication portion which allows the developer to communicate from the second chamber to the first chamber; a first transport screw which is disposed in the first chamber and transports the developer in a first direction from the second communication portion toward the first communication portion; a second transport screw which transports the developer in a second direction from the first communication portion toward the second communication portion; and a developer discharge portion which is provided in a path which continues to the first chamber downstream of the first communication portion in the first direction and which discharges the developer from the developing device, a first discharging step of discharging the developer from the developing device via the developer discharging portion by rotating the first conveying screw in a first rotation direction during a developing operation for developing an electrostatic image formed on an image carrier, while the first communicating portion is in an open state and the second communicating portion is in an open state, and by rotating the second conveying screw in a second rotation direction during the developing operation; an insertion step of inserting a shielding member into the first communication portion through an insertion opening of the developing container to transition from an open state in which the first communication portion is opened to a shielding state in which the first communication portion is shielded; a second discharging step of discharging the developer from the developing device via the developer discharging portion by rotating the first conveying screw in the first rotation direction and rotating the second conveying screw in the second rotation direction in a state in which the shielding member is inserted into the first communicating portion in the inserting step and the second communicating portion is opened; 13. A method for discharging developer from a developing device, comprising:

13. In the second discharge step, The first conveying screw is rotationally driven in the first rotation direction at a speed equal to a driving speed of the first conveying screw when the first conveying screw is rotationally driven in the first rotation direction during the developing operation, and the second conveying screw is rotationally driven in the second rotation direction at a speed equal to a driving speed of the second conveying screw when the second conveying screw is rotationally driven in the second rotation direction during the developing operation.

13. The method for discharging developer from a developing device according to claim 12.

14. In the second discharge step, In the first period, the first conveying screw is rotationally driven in the first rotation direction at a speed slower than a driving speed of the first conveying screw when the first conveying screw is rotationally driven in the first rotation direction during the developing operation, and the second conveying screw is rotationally driven in the second rotation direction at a speed slower than a driving speed of the second conveying screw when the second conveying screw is rotationally driven in the second rotation direction during the developing operation; and, In a second period following the first period, The first conveying screw is rotationally driven in the first rotation direction at a speed equal to a driving speed of the first conveying screw when the first conveying screw is rotationally driven in the first rotation direction during the developing operation, and the second conveying screw is rotationally driven in the second rotation direction at a speed equal to a driving speed of the second conveying screw when the second conveying screw is rotationally driven in the second rotation direction during the developing operation.

13. The method for discharging developer from a developing device according to claim 12.

15. A developing device comprising: a developer carrier that carries and transports a developer containing a toner and a carrier to a development position; a developing container including a first chamber for accommodating the developer to be supplied to the developer carrier, and a second chamber partitioned from the first chamber by a partition wall and through which the developer circulates between the first chamber and a second chamber; a first communication portion that allows the developer to communicate from the first chamber to the second chamber; a second communication portion that allows the developer to communicate from the second chamber to the first chamber; a first conveying screw disposed in the first chamber and configured to convey the developer in a first direction from the second communicating portion toward the first communicating portion; a second conveying screw disposed in the second chamber and configured to convey the developer in a second direction from the first communicating portion toward the second communicating portion; a developer discharge portion provided in a path continuing to the second chamber downstream of the second communication portion in the second direction, the developer discharge portion configured to discharge the developer from the developing device; Equipped with when the first communication portion is open and the second communication portion is open, the first conveying screw is rotationally driven in a first rotation direction and the second conveying screw is rotationally driven in a second rotation direction, thereby discharging the developer from the developing device via the developer discharging portion, the developing container is provided with an insertion opening for inserting a shielding member into the second communicating portion to transition from an open state in which the second communicating portion is opened to a shielding state in which the second communicating portion is shielded, In a state in which the first communication portion is open and the shielding member is inserted into the second communication portion through the insertion opening, the first conveying screw is rotationally driven in the first rotation direction and the second conveying screw is rotationally driven in the second rotation direction, whereby the developer can be discharged from the developing device through the developer discharge portion. A developing device characterized by the above.

16. The developing container has a cover covering the top of each of the first chamber and the second chamber, The insertion opening is provided in the cover.

16. The developing device according to claim 15.

17. The shielding member has a locking portion that locks to an inner surface of the cover when the shielding member is inserted into the second communication portion through the insertion opening.

17. The developing device according to claim 16.

18. A developing device comprising: a developer carrier that carries and transports a developer containing a toner and a carrier to a development position; a developing container including a first chamber for accommodating the developer to be supplied to the developer carrier, and a second chamber partitioned from the first chamber by a partition wall and through which the developer circulates between the first chamber and a second chamber; a first communication portion that allows the developer to communicate from the first chamber to the second chamber; a second communication portion that allows the developer to communicate from the second chamber to the first chamber; a first conveying screw disposed in the first chamber and configured to convey the developer in a first direction from the second communicating portion toward the first communicating portion; a second conveying screw disposed in the second chamber and configured to convey the developer in a second direction from the first communicating portion toward the second communicating portion; a developer discharge portion provided in a path continuing to the first chamber downstream of the first communication portion in the first direction, the developer discharge portion configured to discharge the developer from the developing device; Equipped with when the first communication portion is open and the second communication portion is open, the first conveying screw is rotationally driven in a first rotation direction and the second conveying screw is rotationally driven in a second rotation direction, thereby discharging the developer from the developing device via the developer discharging portion, the developing container is provided with an insertion opening for inserting a shielding member into the first communicating portion to transition from an open state in which the first communicating portion is opened to a shielding state in which the first communicating portion is shielded, In a state in which the shielding member is inserted into the first communicating portion through the insertion opening and in a state in which the second communicating portion is open, the first conveying screw is rotationally driven in the first rotation direction and the second conveying screw is rotationally driven in the second rotation direction, whereby the developer can be discharged from the developing device through the developer discharge portion. A developing device characterized by the above.

19. The developing container has a cover covering an upper portion of each of the first chamber and the second chamber, The insertion opening is provided in the cover.

20. The developing device according to claim 18,

20. The shielding member has a locking portion that locks to an inner surface of the cover when the shielding member is inserted into the first communicating portion through the insertion opening.

20. The developing device according to claim 19.

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