Patent ID: 8588664

Claim:
A developing cartridge comprising: a developing roller configured to rotate about a developing roller axis line, which extends from a plane; a supply roller configured to rotate about a supply roller axis line, which extends parallel to the developing roller axis line, and configured to supply developer to the developing roller; a housing having a pair of opposing sidewalls that support the developing roller and the supply roller from both sides thereof, one sidewall of the pair of opposing sidewalls defining the plane; a developing roller driving gear that is connected to the developing roller; a supply roller driving gear that is connected to the supply roller; and a driving force transmission gear configured to rotate about a gear axis line, which extends parallel to the developing roller axis line, the driving force transmission gear comprising: a first gear part meshed with the developing roller driving gear; and a second gear part meshed with the supply roller driving gear, wherein the driving force transmission gear is configured to transmit a driving force to each of the developing roller driving gear and the supply roller driving gear, wherein the developing roller driving gear is disposed nearer to the plane than the supply roller driving gear and is restrained from moving toward the plane along a direction parallel to the developing roller axis line, and wherein the first gear part forms a first helical tooth pattern and the second gear part forms a second helical tooth pattern, wherein the first helical tooth pattern and the second helical tooth pattern comprise respective tooth traces that follow respective helix pitches of directions different from each other, wherein the first gear part is configured to generate a first force when the driving force transmission gear is rotated, wherein the second gear part is configured to generate a second force when the driving force transmission gear is rotated, the second force being in a direction opposite to a direction of the first force and parallel to the developing roller axis line, wherein the second force is directed away from the plane, and wherein the first force and the second force prevent the developing roller driving gear and the supply roller driving gear from moving in a direction parallel to the gear axis line.