Patent attributes
An image forming apparatus includes a driving source, a rotary element and a coupling device. The coupling device includes an inner coupling having a cylindrical shape with a first rotation axis and a first group of claws arranged to be evenly spaced in a circumferential direction, and an outer coupling having a cylindrical shape with a second rotation axis and a second group of claws arranged to be evenly spaced in a circumference direction to alternately mesh with the first group of claws. At least one of the first and second groups of claws includes claws with pointed tips so as to effectively connect the inner coupling with the outer coupling.