Developing unit

Abstract

A developing unit, comprises: a conveying shaft; a developing conveying portion conveying a developer in an axial direction as the conveying shaft rotates; a discharge opening discharging the developer from the inner wall surface; an accumulating chamber accumulating the discharged developer; and an opening/closing member opening and closing the discharge opening due to its own weight as the rotating body rotates, and being in an open state at the developing position, an opening/closing fulcrum of the opening/closing member being at a lower end portion of the opening/closing member at the developing position, the developing unit being held at a rotating body, and successively being made to oppose a developing position of an image carrier due to rotation of the rotating body.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

An exemplary embodiment of the present invention will be described in detail based on the following figures, wherein:

FIG. 1 is a drawing showing the schematic structure of a rotary developing apparatus which is equipped with developing units of an exemplary embodiment of the present invention;

FIG. 2 is an explanatory diagram schematically illustrating the developing apparatus equipped with the developing units of the exemplary embodiment of the present invention, and explains an opening/closing operation of an opening/closing member and discharging of excess developer from a discharge opening, which accompany rotation of a rotating body;

FIG. 3 is a cross-sectional view of the interior of the developing unit viewed from a lateral direction;

FIG. 4 is a cross-sectional view of the interior of the developing unit viewed from above;

FIG. 5A is an enlarged view in which a vicinity of the discharge opening is enlarged;

FIG. 5B is a drawing showing another structural example of a vicinity of the discharge opening;

FIG. 5C is a drawing showing a modified example of portion C of FIG. 5B;

FIG. 6 is a drawing of a vicinity of the discharge opening at the interior of the developing unit;

FIG. 7 is a perspective view of a vicinity of the discharge opening at the interior of the developing unit;

FIG. 8 is a drawing schematically showing a developer cartridge;

FIG. 9 is a cross-sectional view of the interior of the developing unit seen from a lateral direction, and including the discharge opening portion;

FIG. 10A is a schematic diagram of a cross-section of a state in which the opening/closing member is open;

FIG. 10B is a schematic diagram of a cross-section of a state in which the opening/closing member is closed;

FIG. 11A is a schematic diagram of a cross-section of the state in which the opening/closing member is open;

FIG. 11B is a schematic diagram of a cross-section of the state in which the opening/closing member is closed;

FIG. 12 is a perspective view of a vicinity of the discharge opening at the interior of the developing unit;

FIG. 13 is a perspective view showing the opening/closing member and the discharge opening;

FIG. 14 is a perspective view showing the opening/closing member;

FIG. 15 is a perspective view showing another opening/closing member;

FIG. 16 is a perspective view showing still another opening/closing member;

FIG. 17A is a diagram explaining the flow of the developer in a state in which the developing unit is at a developing position;

FIG. 17B is a diagram explaining a state in which the developing unit has rotated and the opening/closing member is closing; and

FIG. 17C is a diagram explaining a state in which the developing unit has rotated and the opening/closing member is closed.

Claims

1. A developing unit comprising: a conveying shaft provided within the developing unit and rotates;a developing conveying portion that is spiral-shaped, formed at an outer periphery of the conveying shaft, and conveys a developer in an axial direction as the conveying shaft rotates;a discharge opening provided in an inner wall surface that opposes the conveying shaft, and discharging the developer from the inner wall surface;an accumulating chamber accumulating the developer discharged from the discharge opening; andan opening/closing member that is plate-shaped, and opens and closes the discharge opening due to its own weight as the rotating body rotates, and is in an open state at the developing position,the developing unit being held at a rotating body, and successively being made to oppose a developing position of an image carrier due to rotation of the rotating body,the opening/closing member having an opening/closing fulcrum at a lower end portion of the opening/closing member at the developing position.

2. The developing unit of claim 1, wherein an end portion of the opening/closing member that is at a side opposite to the opening/closing fulcrum side is heavier than the opening/closing fulcrum side of the opening/closing member.

3. A developing unit comprising: a conveying shaft provided within the developing unit and rotates;a developing conveying portion that is spiral-shaped, formed at an outer periphery of the conveying shaft, and conveys the developer in an axial direction as the conveying shaft rotates;a discharge opening formed in an inner wall surface that opposes the conveying shaft, and discharging the developer from the inner wall surface;an accumulating chamber accumulating the developer discharged from the discharge opening; andan opening/closing member that is plate-shaped, and opens and closes the discharge opening due to its own weight as the rotating body rotates, and is in an open state at the developing position,a flow regulating portion, whose cross-section narrows in a direction opposing a conveying direction, being formed at a surface of an upstream side end portion of the opening/closing member in the conveying direction, the surface being opposite to the discharge opening,the developing unit being held at a rotating body, and successively being made to oppose a developing position of an image carrier due to rotation of the rotating body.

4. The developing unit of claim 3, wherein the flow regulating portion of the opening/closing member is an inclined surface.

5. The developing unit of claim 3, wherein the flow regulating portion of the opening/closing member is a step portion.

6. The developing unit of claim 3, wherein a downstream side end portion of the opening/closing member in the conveying direction has a configuration that the flow regulating portion of the opening/closing member is rotated at 180°.

7. The developing unit of claim 1, wherein the conveying shaft has a developer reverse direction conveying portion that is shaped as a spiral directed reversely to the developer conveying portion, the developer reverse direction conveying portion being provided further than an end portion of the developer conveying portion toward downstream of the conveying direction.

8. The developing unit of claim 3, wherein the conveying shaft has a developer reverse direction conveying portion that is shaped as a spiral directed reversely to the developer conveying portion, the developer reverse direction conveying portion being provided further than an end portion of the developer conveying portion toward downstream of the conveying direction.

9. The developing unit of claim 1, wherein an interval between the inner wall surface and the developer conveying portion in a vicinity of an upstream side of the discharge opening in the conveying direction is narrowed.

10. The developing unit of claim 3, wherein an interval between the inner wall surface and the developer conveying portion in a vicinity of an upstream side of the discharge opening in the conveying direction is narrowed.

11. The developing unit of claim 9, wherein an outer periphery of the developer conveying portion in a vicinity of an upstream side of the discharge opening in the conveying direction is larger than the outer periphery of the developer conveying portion not in the vicinity of an upstream side of the discharge opening..

12. The developing unit of claim 10, wherein an outer periphery of the developer conveying portion in a vicinity of an upstream side of the discharge opening in the conveying direction is larger than the outer periphery of the developer conveying portion not in the vicinity of an upstream side of the discharge opening.

13. The developing unit of claim 9, wherein the inner wall surface in a vicinity of an upstream side of the discharge opening in the conveying direction is closer to the developer conveying portion than the inner wall surface not in the vicinity of the upstream side of the discharge opening.

14. The developing unit of claim 10, wherein the inner wall surface in a vicinity of an upstream side of the discharge opening in the conveying direction is closer to the developer conveying portion than the inner wall surface not in the vicinity of the upstream side of the discharge opening.

15. A developing unit comprising: a conveying shaft means provided within the developing unit and rotates;a developing conveying means for conveying a developer in an axial direction as the conveying shaft rotates, the developing conveying means being spiral-shaped, and formed at an outer periphery of the conveying shaft, and;a discharge opening means for discharging the developer from the inner wall surface, the discharge opening means being provided in an inner wall surface which opposes the conveying shaft, and;an accumulating chamber means for accumulating the developer discharged from the discharge opening; andan opening/closing means for opening and closing the discharge opening due to its own weight as the rotating body rotates, the opening/closing means being plate-shaped, and being in an open state at the developing position,the developing unit being held at a rotating body, and successively being made to oppose a developing position of an image carrier due to rotation of the rotating body,the opening/closing means having an opening/closing fulcrum at a lower end portion of the opening/closing means at the developing position.