Patent ID: 8320057
Filing Date: 2012-11-27
Classification: G02B

Abstract:
1. A lens unit comprising: a first lens having positive power; an aperture stop; a second lens having negative power; a meniscal third lens having positive power; and a fourth lens including an object side surface and an image side surface, each being aspherical and each including at least one inflection point, with the image side surface being concave at an image side; wherein the first lens, the aperture stop, the second lens, the third lens, and the fourth lens are arranged in order from an object side toward the image side; the first lens includes an image side surface that is convex at the image side; the second lens includes an object side surface that is convex at the object side; and the object side surface of the second lens includes a central portion that is concave at the object side and a peripheral portion that is convex at the object side.