Patent ID: 8311455

Claim:
A driving force member for receiving rotational driving force, comprising: a base portion having a perimeter; a projection portion that extends beyond the perimeter of base portion in a direction generally perpendicular to a longitudinal axis of the base portion, comprising three planar surfaces, each of the three planar surfaces forming portions of three sides of an equilateral triangle, respectively, each of the three planar surfaces correspond to a first portion of the length of the three respective sides of the equilateral triangle, and each planar surface is offset from the center of each respective side of the triangle; and three joining portions joining each of the three planar surfaces, each of the three joining portions are recessed relative to planar surface adjacent to the respective joining portion, each of the three joining portions extend from near the center of the respective sides of the equilateral triangle and one of the planar surfaces toward another of the planar surfaces, and the three joining portions lay entirely within the equilateral triangle; wherein the three joining portions are one or more of substantially concave or substantially convex.