Patent ID: 8736985
Filing Date: 2014-05-27
Classification: G02B

Abstract:
1. A lens optical system comprising first to fourth lenses that are sequentially arranged from an object, and which are between the object and an image sensor on which an image of the object is formed, wherein the first lens has a positive (+) refractive power and an incident surface that is convex toward the object, the second lens has a negative (−) refractive power and both surfaces that are concave, the third lens has a positive (+) refractive power and has a meniscus shape that is convex toward the image sensor, and the fourth lens has a negative (−) refractive power and at least one of an incident surface and an exit surface thereof is an aspherical surface, and wherein the lens optical system satisfies the following inequality, wherein “θ” denotes an angle of view of the lens optical system and “f” denotes a focal length of the lens optical system, wherein the angle of view (θ) of the lens optical system is greater than or equal to 66°, wherein a central portion of the incident surface of the fourth lens is convex toward the object and a portion around the central portion of the incident surface is concave toward the object, wherein the incident surface of the fourth lens has two or three inflection points from the center portion toward an edge thereof, wherein the center portion of the incident surface of the fourth lens is convex toward the object and the incident surface of the fourth lens gradually changes to be concave and convex from the center portion toward an edge thereof, or the center portion of the incident surface of the fourth lens is convex toward the object and the incident surface of the fourth surface gradually changes to be concave, convex, and concave from the center portion toward an edge thereof, and wherein the angle of view (θ) of the lens optical system is smaller than 70°, the focal length (f) of the lens optical system is smaller than 4.5 mm, and an overall length (L) of the lens optical system is smaller than 5 mm.