US Patent 7472620 Resin double helical gear and gear train using same

There are provided a resin double helical gear capable of reducing operation noises and vibrations of an image forming system, such as an ink jet printer, which is arranged in the vicinity of an operator, and a gear train using the same and having a smaller number of parts. The gear train 2 for ink jet printer 1 includes a first resin double helical gear 5 which is mounted on an output shaft 4 of a motor 3 so as to be rotatable therewith, and a second resin double helical gear 6 which is mounted on a paper feeding roller shaft 7 so as to be rotatable therewith and which meshes with the first resin double helical gear 5.