Patent attributes
A gear train for an ink jet printer includes an output gear of a motor, a first idle gear meshing with the output gear, a second idle gear rotatable with the first idle gear, and a driven gear which is mounted on a roller shaft so as to be rotatable therewith and which meshes with the second idle gear. A resin double helical gear is used as each of the output gear and the first idle gear, and a spur gear is used as each of the second idle gear and the driven gear. The resin double helical gear may have a meshing relief portion formed by cutting a chevron-shaped top portion in a central portion in face width directions, which is arranged in a butt portion between a first die and a second die, from a tooth crest to a portion near a bottom lane so as to decrease a tooth thickness.
