Imaging lens module
An imaging lens module includes a fixed diaphragm and an optical module. The optical module includes first, second, third, fourth and fifth lenses arranged from an object side to an image side in a sequence of: the first lens, having a negative refractive power, a convex surface disposed towards the object side, and a concave surface disposed towards the image side; the diaphragm; the second lens having a positive refractive power and a convex lens disposed towards the image side; and the third lens; being a meniscus negative lens; the fourth lens, being a positive lens, and adhered with the third lens to form a composite lens; the fifth lens, having a positive refractive power, such that the imaging lens module is a lens module with the features of high imaging quality and high yield rate.
1. An imaging lens module, comprising a fixed diaphragm and an optical module, and the optical module comprising first, second, third, fourth and fifth lenses arranged from an object side to an image side in a sequence of:
the first lens, having a negative refractive power, a convex surface disposed towards the object side, and a concave surface disposed towards the image side;
the diaphragm;
the second lens, having a positive refractive power, a convex surface disposed towards the image side;
the third lens, being a negative meniscus lens, with the absolute value of a radius of curvature facing the image side smaller than the absolute value of a radius of curvature facing the object side;
the fourth lens, being a positive lens, with the absolute value of a radius of curvature facing the image side greater than the absolute value of a radius of curvature facing the object side, wherein the third and fourth lenses are adhered to form a composite lens; and the fifth lens, having a positive refractive power;
wherein 1<|f|/|f 2 |<1.5, and |f 2 | is the absolute value of the focal length of the second lens, and |f| is the absolute value of the focal length of the whole lens module.
2. The imaging lens module of claim 1 , wherein at least one surface of the first lens is an aspheric surface.
3. The imaging lens module of claim 1 , wherein at least one surface of the second lens is an aspheric surface.
4. The imaging lens module of claim 1 , wherein at least one surface of the fifth lens is an aspheric surface.
5. The imaging lens module of claim 1 , wherein 0.6<|f|/|f 1 |<1.0, and |f| is the absolute value of the focal length of the first lens, and |f| is the absolute value of the focal length of the whole lens module.
6. The imaging lens module of claim 1 , wherein 0.04<|f|/|f 5 |<0.25, and |f 5 | is the absolute value of the focal length of the fifth lens, and |f| is the absolute value of the focal length of the whole lens module.
7. The imaging lens module of claim 1 , wherein an aspheric surface is in a shape satisfying the formula of:
z
=
ch
2
1
+
[
1
-
(
k
+
1
)
c
2
h
2
]
0.5
+
A
h
4
+
Bh
6
+
Ch
8
+
Dh
10
+
Eh
12
+
Gh
14
+
…
and z is the value of a reference position with respect to a vertex of the surface along the optical axis and at a position with a height h; k is a conic constant; c is the reciprocal of a radius of curvature; and A, B, C, D, E, G are coefficients of high level aspheric surface.