Patent ID: 7391581

Claim:
A lens barrel for holding an optical lens system including a plastic lens formed by molding therein, said plastic lens ending up having decentering eccentricity of an optical axis from a geometric axis thereof due to a manufacturing error entailed by a molding die used for said plastic lens, said lens barrel comprising: a lens holding barrel for fixedly holding said plastic lens therein; and locating and joining means for placing said plastic lens in a location where said plastic lens is in a desired axial position and an optical axis of said plastic lens is coaxial with a geometric axis of said lens holding barrel and fixedly joining said plastic lens to said lens holding barrel in said location; said locating and joining means comprising: at least three axial projections of predetermined equal axial length which extend in an axial direction from a marginal portion of said plastic lens and are disposed at regular angular intervals on a circumference of a circle with a specified radius; and at least two groups of locating means comprising axial bores for receiving said axial projections respectively, each said group of locating means comprising at least two sets of said axial bores of the same number as said axial projections which are formed in said lens holding barrel and disposed at regular angular intervals on a circumference of a circle with the same radius as said circle on said circumference of which said axial projections are disposed; wherein said axial bores are equal in axial depth to one another in a same set and different in axial depth by set, and said circles of said locating means are off-centered from one another; and wherein said axial projections are fitted in said axial bores of one of said at least two sets selected for axial position adjustment of said plastic lens of one of said groups selected for coaxial adjustment of said plastic lens, respectively, so as thereby to place said plastic lens in said location and join said plastic lens to said lens holding barrel.