| 主权项 |
1. An optical imaging lens, sequentially from an object side to an image side along an optical axis, comprising:
first, second, third and fourth lens elements, each of said first, second, third and fourth lens elements having refracting power, an object-side surface facing toward the object side, an image-side surface facing toward the image side and a central thickness defined along the optical axis, wherein: said first lens element has positive refracting power, said object-side surface thereof comprises a convex portion in a vicinity of the optical axis, and said image-side surface thereof comprises a convex portion in a vicinity of the optical axis; said second lens element has negative refracting power, said object-side surface thereof comprises a concave portion in a vicinity of a periphery of the second lens element, and said image-side surface thereof comprises a concave portion in a vicinity of a periphery of the second lens element; said third lens element has positive refracting power, said object-side surface of said third lens element is a concave surface, and said image-side surface thereof comprises a convex portion in a vicinity of the optical axis; said fourth lens element has negative refracting power, said fourth lens element is constructed by plastic material, and said object-side surface thereof comprises a convex portion in a vicinity of a periphery of the fourth lens element; wherein the optical imaging lens comprises no other lenses having reflecting refracting power beyond the four lens elements; wherein an air gap between the second lens element and the third lens element along the optical axis is larger than the central thickness of the fourth lens element along the optical axis; and wherein Fno is less than 2.46; wherein the sum of all three air gaps from the first lens element to the fourth lens element along the optical axis is AAG, the central thickness of the second lens element along the optical axis is CT2 and CT2 and AAG satisfy the equation:
2.55≦AAG/CT2. |
