Patent ID: 7474868
Filing Date: 2009-01-06
Classification: B65H,G03G

Abstract:
1. A belt unit comprising: a drive roller that rotates upon receiving a driving force from a drive motor; a follower roller rotatable as a result of rotation of the drive roller; and an endless belt looped around the drive roller and follower roller, and formed of a resilient material, wherein the drive roller transfers a first force based on the driving force to the endless belt to circularly move at a first velocity at a first boundary between the drive roller and the endless belt, the first velocity providing a first fluctuation, wherein the endless belt transfers a second force based on the first force to the follower roller to rotate, the endless belt moving at a second velocity at a second boundary between the follower roller and the endless belt, the second velocity providing a second fluctuation, wherein a transmission parameter with respect to at least one of the drive roller, the follower roller and the endless belt is set so that the second fluctuation is smaller than the first fluctuation, wherein the endless belt has a stretch property, wherein the transmission parameter is set so that the endless belt transfers the second force while stretching and contracting to absorb the second fluctuation, and wherein the transmission parameter is set so that the following relationship is established: in which A: a maximum amplitude of cumulative displacement during one circuit of the endless belt, and ΔL: a difference of a length of the endless belt from a natural length is indicated.