US 11,947,284 B2
Developing device having magnetic supplying roller
Naoki Mugita, Ibaraki (JP)
Assigned to CANON KABUSHIKI KAISHA, Tokyo (JP)
Filed by CANON KABUSHIKI KAISHA, Tokyo (JP)
Filed on Jan. 6, 2023, as Appl. No. 18/093,881.
Claims priority of application No. 2022-011047 (JP), filed on Jan. 27, 2022.
Prior Publication US 2023/0259052 A1, Aug. 17, 2023
Int. Cl. G03G 15/08 (2006.01); G03G 15/09 (2006.01)
CPC G03G 15/0921 (2013.01) [G03G 15/0812 (2013.01)] 11 Claims
OG exemplary drawing
 
1. A developing device comprising:
a developing container configured to accommodate a developer containing toner and a carrier;
a developing roller configured to carry and convey the toner to a developing position where an electrostatic latent image formed on an image bearing member is developed with the toner;
a supplying roller provided opposed to the developing roller and configured to supply only the toner to the developing roller while carrying and conveying the developer supplied from the developing container, said supplying roller being rotated in a rotational direction opposite to a rotational direction of the developing roller in a position where the supplying roller and the developing roller oppose each other;
a first magnet provided non rotationally and fixedly inside the developing roller and including a first magnetic pole;
a second magnet provided non rotationally and fixedly inside the supplying roller and including:
a second magnetic pole which is provided opposed to the first magnetic pole in a position where the supplying roller opposes the developing roller and which is different in polarity from the first magnetic pole,
a third magnetic pole which is provided upstream of and adjacent to the second magnetic pole with respect to the rotational direction of the supplying roller and which is different in polarity from the second magnetic pole,
a fourth magnetic pole which is provided upstream of and adjacent to the third magnetic pole with respect to the rotational direction of the supplying roller and which is different in polarity from the third magnetic pole, and
a fifth magnetic pole which is provided upstream of and adjacent to the fourth magnetic pole with respect to the rotational direction of the supplying roller and which is different in polarity from the fourth magnetic pole; and
a regulating member provided opposed to the fourth magnetic pole and configured to regulate an amount of the developer carried on the supplying roller,
wherein an absolute value of a maximum magnetic flux density of the third magnetic pole is larger than an absolute value of a maximum magnetic flux density of the fourth magnetic pole with respect to a normal direction to an outer peripheral surface of the supplying roller, and an absolute value of a maximum magnetic flux density of the fourth magnetic pole is larger than an absolute value of a maximum magnetic flux density of the fifth magnetic pole with respect to the normal direction, and
wherein in a case that positions where a magnetic flux density of the fourth magnetic pole is 50% of the maximum magnetic flux density of the fourth magnetic flux density with respect to the normal direction are a first position and a second position, with respect to the rotational direction of the supplying roller, the position where the magnetic flux density of the fourth magnetic pole becomes maximum with respect to the normal direction is downstream of an intermediary position between the first position and the second position by 3 degrees or more.