A lens barrel has a base, a second lens holder frame holding a second lens group, a first lens holder frame holding a first lens group, a cam ring, and a fixed ring. The second lens holder frame has three guides projecting axially from an outer circumferential portion of an annular plate and disposed...http://www.google.com/patents/US7236312?utm_source=gb-gplus-sharePatent US7236312 - Collapsible lens barrel and imaging device
