Imaging lens and portable electronic apparatus having the same

1. 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 object-side surface of said first lens element having a convex portion in a vicinity of an optical axis of said imaging lens, said image-side surface of said first lens element having a convex portion in a vicinity of the optical axis;

said object-side surface of said second lens element has a convex portion in a vicinity of the optical axis, and said image-side surface of said second lens element has a concave portion in a vicinity of the optical axis;

said fourth lens element has a negative refractive power, and said object-side surface thereof has a concave portion in a vicinity of the optical axis;

wherein said imaging lens satisfies 10.5≧EFL/CT 1 ≧5.30, CT 1 /CT 2 ≦1.50, 13.0≧CT 3 /AC 34 ≧4.80 and 1.70≧CT 3 /CT 1 ≧1.40, where EFL represents an effective focal length of said imaging lens, CT 1 represents a distance between said object-side surface and said image-side surface of said first lens element at the optical axis, CT 2 represents a distance between said object-side surface and said image-side surface of said second lens element at the optical axis, CT 3 represents a distance between said object-side surface and said image-side surface of said third lens element at the optical axis, and AC 34 represents 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,

wherein said imaging lens does not include any lens element with refractive power other than said first, second, third, and fourth lens elements.

2. The imaging lens as claimed in claim 1 , further satisfying 5.0≧ALT/CT 1 ≧3.55, where ALT represents a sum of the distance between said object-side surface and said image-side surface of said first lens element at the optical axis, the distance between said object-side surface and said image-side surface of said second lens element at the optical axis, the distance between said object-side surface and said image-side surface of said third lens element at the optical axis, and a distance between said object-side surface and said image-side surface of said fourth lens element at the optical axis.

3. The imaging lens as claimed in claim 1 , further satisfying 3.9≧ALT/CT 3 ≧2.65, where ALT represents a sum of the distance between said object-side surface and said image-side surface of said first lens element at the optical axis, the distance between said object-side surface and said image-side surface of said second lens element at the optical axis, the distance between said object-side surface and said image-side surface of said third lens element at the optical axis, and a distance between said object-side surface and said image-side surface of said fourth lens element at the optical axis.

4. The imaging lens as claimed in claim 1 , further satisfying 14.00≧AAG/AC 34 ≧8.00, 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 the 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.

5. The imaging lens as claimed in claim 4 , further satisfying 5.0≧ALT/CT 1 ≧3.55, where ALT represents a sum of the distance between said object-side surface and said image-side surface of said first lens element at the optical axis, the distance between said object-side surface and said image-side surface of said second lens element at the optical axis, the distance between said object-side surface and said image-side surface of said third lens element at the optical axis, and a distance between said object-side surface and said image-side surface of said fourth lens element at the optical axis.

6. The imaging lens as claimed in claim 5 , further satisfying CT 3 /CT 4 ≧1.75, where CT 4 represents the distance between said object-side surface and said image-side surface of said fourth lens element at the optical axis.

7. The imaging lens as claimed in claim 1 , wherein said object-side surface of said fourth lens element further has a convex portion in a vicinity of a periphery of said fourth lens element.

8. A portable electronic apparatus comprising:

a housing; and

an imaging module disposed in said housing, and including an imaging lens as claimed in claim 1 , a barrel on which said imaging lens is disposed, a seat unit on which said barrel is disposed, and an image sensor disposed at the image side and operatively associated with said imaging lens for capturing images.

9. The portable electronic apparatus as claimed in claim 8 , wherein said seat unit includes a first seat portion including an inner section in which said barrel is disposed, and an outer section that surrounds said inner section, said inner section of said first seat portion, said barrel, and said imaging lens being movable together with respect to said image sensor along the optical axis.

10. The portable electronic apparatus as claimed in claim 9 , wherein said seat unit further includes a second seat portion, which is disposed between said outer section of said first seat portion and said image sensor, and which is disposed to abut against said outer section.