Patent ID: 8792188

Claim:
An imaging lens comprising first, second, third, and fourth lens elements arranged from an object side to an image side in the given order, each of said first, second, third, and fourth lens elements having an object-side surface facing toward the object side and an image-side surface facing toward the image side, wherein: said first lens element has a positive refractive power; said second lens element has a negative refractive power, said object-side surface of said second lens element being a concave surface, said image-side surface of said second lens element being a concave surface; said third lens element has a positive refractive power; and said object-side surface of said fourth lens element is a curved surface and has a convex portion in a vicinity of an optical axis of said imaging lens, and a concave portion in a vicinity of a periphery of said fourth lens element; wherein said imaging lens satisfies AAG/CT3≧1.3, where AAG represents a sum of a distance between said image-side surface of said first lens element and said object-side surface of said second lens element at the optical axis, a distance between said image-side surface of said second lens element and said object-side surface of said third lens element at the optical axis, and a distance between said image-side surface of said third lens element and said object-side surface of said fourth lens element at the optical axis, and CT3 represents a distance between said object-side surface and said image-side surface of said third lens element at the optical axis; and wherein said imaging lens does not include any lens element with refractive power other than said first, second, third, and fourth lens elements.