Patent ID: 9594338
Date: 2017-03-14
CPC Classifications: G03G

Claim:
1. An image forming apparatus comprising: a housing; a photosensitive drum that is rotatably supported by the housing about a first shaft portion, an electrostatic latent image being formed on a peripheral surface of which, and a developer image being carried thereby; a cleaning member that is supported by the housing, contacts the peripheral surface of the photosensitive drum, and cleans up the peripheral surface; a driving transmission portion that transmits a rotation driving force about the first shaft portion to the photosensitive drum; and a movement mechanism that reciprocates the photosensitive drum in an axial direction of the first shaft portion at a predetermined cycle, a charging roller that has a third shaft portion parallel to the first shaft portion, rotates about the third shaft portion, contacts the peripheral surface of the photosensitive drum, and charges the peripheral surface; and a brush roller that has a fourth shaft portion parallel to the first shaft portion, rotates about the fourth shaft portion, and cleans up a surface of the charging roller, wherein the movement mechanism includes: a first rotation gear that is fixed to the photosensitive drum and integrally rotates with the photosensitive drum about the first shaft portion; a second rotation gear that is arranged facing the first rotation gear in the axial direction, has teeth different in number from teeth of the first rotation gear, is restricted in a position thereof in the axial direction, and rotates about the first shaft portion with a predetermined speed difference relative to the first rotation gear; a first pair of rotation gears rotatable about a second shaft portion parallel to the first shaft portion of the photosensitive drum; and a second pair of rotation gears rotatable about the fourth shaft portion, the first pair of rotation gears including: a first intermediate gear that engages with the first rotation gear and a second intermediate gear that is arranged adjacent to the first intermediate gear in the axial direction, engages with the second rotation gear, has teeth different in number from teeth of the first intermediate gear, and integrally rotates with the first intermediate gear, the second pair of rotation gears including: a third rotation gear that engages with the first intermediate gear and integrally rotates with the brush roller and a fourth rotation gear that is arranged adjacent to the third rotation gear in the axial direction, has teeth different in number from teeth of the third rotation gear, engages with the second intermediate gear, is restricted in a position thereof in the axial direction, and rotates with a predetermined speed difference relative to the third rotation gear, the first rotation gear has a first cam surface that is arranged at a side surface thereof facing the second rotation gear and has different projection amounts in the axial direction along a circumferential direction thereof, the second rotation gear has a second cam surface that is arranged at a side surface thereof facing the first rotation gear, has different projection amounts in the axial direction along a circumferential direction thereof, and is capable of contacting the first cam surface, the third rotation gear has a third cam surface that is arranged at a side surface thereof facing the fourth rotation gear and has different projection amounts in the axial direction along a circumferential direction thereof, the fourth rotation gear has a fourth cam surface that is arranged at a side surface thereof facing the third rotation gear, has different projection amounts in the axial direction along a circumferential direction thereof, and is capable of contacting the third cam surface, the second rotation gear rotates with the speed difference relative to the first rotation gear as a result of the transmission of the rotation driving force from the first rotation gear to the second rotation gear via the first intermediate gear and the second intermediate gear when the photosensitive drum rotates with the rotation driving force, and the photosensitive drum reciprocates in the axial direction as a result of contact between the first cam surface and the second cam surface the brush roller rotates with transmission of the rotation driving force from the first intermediate gear to the third rotation gear and the fourth rotation gear rotates with the speed difference relative to the third rotation gear as a result of transmission of the rotation driving force from the second intermediate gear to the fourth rotation gear when the photosensitive drum rotates with the rotation driving force, and the brush roller reciprocates in the axial direction as a result of contact between the third cam surface and the fourth cam surface.