Developing apparatus having air discharge

12066,771

17/376300

July 15, 2021

A developing apparatus includes a developing container to accommodate a developer and having first and second chambers divided by a partition wall for supplying the developer to a rotatable developing member and first and second communicating portions to allow the developer to move between first and second chambers by conveyance screws. A third communicating portion is disposed between the first and second communicating portions and above the conveyance screws to allow air inside the developing container to move between the first chamber and the second chamber. The developing container further includes a third chamber disposed above the second chamber in the vertical direction and accommodates initial developer in an unused state of the developing apparatus, and an opening portion for discharging the air inside the developing container to outside of the developing container is provided in the third chamber, with the opening being disposed above the third chamber.

CANON KABUSHIKI KAISHA (Tokyo, JP)

CANON KABUSHIKI KAISHA (Tokyo, JP)

1. A developing apparatus comprising: a rotatable developing member configured to bear and convey developer containing a toner and a carrier so as to develop an electrostatic latent image formed on an image bearing member; a developing container configured to accommodate the developer, the developing container comprising a first chamber supplying the developer to the rotatable developing member, a second chamber, and a partition wall separating the first chamber and the second chamber, the developer circulating between the first chamber and the second chamber; a first communicating portion configured to allow the developer to move from the second chamber to the first chamber; a second communicating portion configured to allow the developer to move from the first chamber to the second chamber; a first conveyance screw disposed in the first chamber, and configured to convey the developer in a first direction from the first communicating portion toward the second communicating portion; a second conveyance screw disposed in the second chamber, and configured to convey the developer in a second direction from the second communicating portion toward the first communicating portion; and a third communicating portion disposed downstream of the first communicating portion and upstream of the second communicating portion in the first direction, disposed above a rotational axis of the first conveyance screw and a rotational axis of the second conveyance screw in a vertical direction, wherein the developing container further comprises a third chamber disposed above the second chamber in the vertical direction, wherein an opening portion for discharging air inside the developing container to outside of the developing container is provided in the third chamber, the opening portion being disposed above the third communication portion, wherein in a sealing state where a sealing member is stuck to the developing container, the second chamber is not in communication with the third chamber and initial developer is sealed in the third chamber by the sealing member stuck to the developing container, the air inside the developing container communicates between the first chamber and the second chamber through the third communicating portion, and the air inside the developing container does not communicate between the second chamber and the third chamber, and wherein in an unsealed state where the sealing member is not stuck to the developing container, the second chamber is in communication with the third chamber and the initial developer is not sealed in the third chamber, the air inside the first chamber is allowed to move into the second chamber through the third communication portion, the air inside the second chamber is allowed to move into the third chamber, and the air inside the third chamber is able to be discharged to outside of the developing container through the opening portion.

2. The developing apparatus according to claim 1 , wherein the developing container comprises a first case portion configured to accommodate the developer and a second case portion fitted to the first case portion and configured to cover a part of an outer circumferential surface of the rotatable developing member, the first conveyance screw and the second conveyance screw being disposed in the first case portion, and wherein the third chamber is disposed in the second case portion.

3. The developing apparatus according to claim 1 , wherein in the sealing state, the opening portion is able to discharge the air inside the third chamber to outside of the developing container.

4. The developing apparatus according to claim 1 , wherein in the sealing state, an uppermost edge of the third communicating portion is disposed below a part, on a side of the partition wall, of a sticking portion in the vertical direction, the sticking portion being a portion where the sealing member is stuck to the developing container.

5. The developing apparatus according to claim 1 , further comprising a magnet non-rotatably fixedly disposed inside the rotatable developing member, the magnet comprising a first magnetic pole and a second magnetic pole, the second magnetic pole being disposed downstream of the first magnetic pole in a rotational direction of the rotatable developing member, the first magnetic pole and the second magnetic pole being disposed adjoiningly to each other and having a same polarity, wherein an uppermost edge of the third communicating portion is disposed below a position where a magnetic flux density of the first magnetic pole in a normal direction of the rotatable developing member becomes maximum, in the vertical direction.

6. The developing apparatus according to claim 1 , wherein the third communicating portion is formed across an area equal to or more than 90% of an area between a downstream end of the first communicating portion and an upstream end of the second communicating portion in the first direction.

7. The developing apparatus according to claim 1 , wherein a filter configured to catch the toner is disposed in the opening portion.

8. The developing apparatus according to claim 7 , wherein a filter cover configured to cover the filter is disposed above the filter in the vertical direction so as to overlap with the filter.

9. The developing apparatus according to claim 1 , wherein in the sealing state, air is movable between the third chamber and outside of the developing container through the opening portion.

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