Patent ID: 7885006

Claim:
A lens unit comprising: a lens array including a plurality of lens pairs arranged in a substantially linear arrangement, each of said lens pairs including a first lens for forming an inverted reduced-size image of an object and a second lens for forming an inverted enlarged-size image of the inverted reduced-size image; a first light blocking member disposed between the first lenses and the second lenses, said first light blocking member including first apertures; and a second light blocking member including second apertures arranged in a substantially linear arrangement corresponding to an arrangement interval of the lens pairs, said second apertures having different opening portion shapes depending on a position of the lens pairs in an optical axis direction of the lens pairs, wherein said second light blocking member is disposed between the first lenses and the object plane at a position away from the object plane by a distance greater than a threshold value PO, said second apertures having an opening portion on a side of the object plane smaller than an opening portion on a side of the first lenses, and wherein said first lenses have a radius RY 1 in the arrangement direction; said first lenses have a focal length F 1 ; said first lenses have a first principal plane situated away from the object plane by distance SO; and said first apertures have an opening radius RAY in the arrangement direction so that the following equation is satisfied: PO = SO - F ⁢ ⁢ 1 RY ⁢ ⁢ 1 · F ⁢ ⁢ 1 + SO · RAY ⁢ RAY · SO .