Camera lens

A camera lens is disclosed. The camera lens includes five piece ultra-thin and high-luminous flux wide angle lenses with excellent optical properties as follows: a first lens with positive refractive power; a second lens with negative refractive power; a third lens with positive refractive power; a fourth lens with positive refractive power; a fifth lens with negative refractive power which are arranged in an order from an object side to an image side. The camera lens satisfies specified conditions.

FIELD OF THE INVENTION

The present invention relates to a camera lens, and more particularly to a camera lens very suitable for mobile phone camera module and WEB camera lens etc. equipped with high-pixel camera elements such as CCD, CMOS etc.

DESCRIPTION OF RELATED ART

In recent years, various camera devices equipped with camera elements such as CCD, CMOS are extensively popular. Along with development on camera lens toward miniaturization and high performance, ultra-thin and high-luminous flux (Fno) wide angle camera lenses with excellent optical properties are needed.

The technology related to the camera lens comprises five piece ultra-thin and wide angle lenses with excellent optical properties and with chromatic aberration sufficiently corrected is developed gradually. The camera lens mentioned in the proposal of prior reference documents 1, 2 is composed of five piece lenses which are arranged sequentially from object side as follows: a first lens with positive refractive power; a second lens with negative refractive power; a third lens with positive refractive power; a fourth lens with positive refractive power and a fifth lens with negative refractive power.

The camera lens disclosed in embodiment 1˜5 of the prior reference document 1 is composed of above mentioned 5 piece lenses, but shape of the first lens and the second lens is improper and ratio of center thickness of the fourth lens to overal focal distance of the camera lens is insufficient; so TTL/LH≧1.58 it is not sufficiently ultra-thin.

The camera lens disclosed in embodiment 1˜6 of the prior reference document 2 is composed of above mentioned 5 piece lenses, but shape of the second lens and refractive power distribution of the second lens is improper and ratio of center thickness of the fourth lens to overall focal distance of the camera lens is insufficient; so it is not sufficiently ultra-thin.

PRIOR REFERENCE DOCUMENTS

Therefore, it is necessary to provide a novel camera lens to solve the above-mentioned technical problem.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

A camera lens LA in accordance with an embodiment of the present disclosure includes, in an order from an object side to an image side, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, and a fifth lens L5.

A glass plate GF is arranged between the fifth lens L5 and the imaging surface. And a glass cover or an optical filter having the function of filtering IR can serve as the glass plate GF. Moreover, it shall be OK if no glass plate GF is arranged between the fifth lens L5 and the imaging surface.

The first lens has positive refractive power; the second lens has negative refractive power; the third lens has positive refractive power; the fourth lens has positive refractive power; the fifth lens has negative refractive power. Moreover, the surfaces of the five lenses should be designed as the aspheric shape preferably in order to correct the aberration well.

The camera lens LA satisfies the following conditions (1)˜(6):
0.60≦f1/f≦0.75  (1);
−1.40≦f2/f≦−1.25  (2);
5.20≦f3/f≦20.00  (3);
−1.20≦(R1+R2)/(R1−R2)≦−0.88  (4);
0.06≦(R3+R4)/(R3−R4)≦0.50  (5);
0.19≦d7/f≦0.23  (6); where,
f: overall focal distance of the camera lens;
f1: focal distance of the first lens L1;
f2: focal distance of the second lens L2;
f3: focal distance of the third lens L3;
R1: the curvature radius of the first lens L1's object side surface;
R2: the curvature radius of the first lens L1's image side surface;
R3: curvature radius of the second lens L2's object side surface;
R4: curvature radius of the second lens L2's image side surface;
d7: center thickness of the fourth lens L4.

The positive refractive power of the first lens L1 is specified in the condition (1). It is difficult for development of wide angle trend and hard to correct the aberration when the numerical range exceeds the lower limit specified in the condition (1) because the positive refractive power of the first lens L1 becomes too strong; on the contrary, when the numerical range exceeds the upper limit specified, the development of ultra-thin trend cannot be implemented easily because the refractive power of the first lens L1 becomes too weak

Therefore, numerical range of condition (1) should be set within the numerical range of the following condition (1-A) preferably,
0.65≦f1/f≦0.75  (1-A)

The negative refractive power of the second lens L2 is specified in the condition (2). Moreover, the problems, such as correction of chromatic aberration on axle and outside of axle, etc. cannot be implemented easily along development of ultra-thin and wide angle trend outside the range of the condition (2).

Therefore, numerical range of condition (2) should be set within the numerical range of the following condition (2-A) preferably,
−1.38≦f2/f≦−1.28  (2-A)

The positive refractive power of the third lens L3 is specified in the condition (3). Moreover, chromatic aberration on axle and outside of axle cannot be cannot be easily corrected along development of ultra-thin outside the range of the condition (3).

Therefore, numerical range of condition (3) should be set within the numerical range of the following condition (3-A) preferably,
5.80≦f3/f≦18.50  (3-A)

The shape of the first lens L1 is specified in the condition (4). Moreover, high order aberration like aberration of spherical surface cannot be corrected easily along development of ultra-thin and wide angle trend outside the range of the condition (4).

Therefore, numerical range of condition (4) should be set within the numerical range of the following condition (4-A) preferably,
−1.10≦(R1+R2)/(R1−R2)<−0.88  (4-A).

Shape of the second lens L2 is specified in the condition (5). Moreover, chromatic aberration on axle cannot be corrected easily along development of ultra-thin and wide angle trend outside the range of the condition (5).

Therefore, numerical range of condition (5) should be set within the numerical range of the following condition (5-A) preferably,
0.08≦(R3+R4)/(R3−R4)≦0.30  (5-A)

Ratio of center thickness of the fourth lens to the overall focal distance of the camera lens is specified in condition (6). Moreover, the development of ultra-thin and wide angle trend cannot be implemented easily outside the range of the condition (6).

The fourth lens L4 has positive refractive power and meets the following condition (7).
0.50≦f4/f≦0.72  (7); where,
f: overall focal distance of the camera lens
f4: focal distance of the fourth lens L4

The positive refractive power of the fourth lens L4 is specified in the condition (7). The development of ultra-thin and wide angle trend is very effective though meeting the condition (7) when chromatic aberration on axle and outside of axle is sufficiently correct.

Therefore, numerical range of condition (7) should be set within the numerical range of the following condition (7-A) preferably,
0.68≦f4/f≦0.72  (7-A)

The camera lens also meets the following condition (8):
0.10≦d6/f≦0.13  (8); where,
f: overall focal distance of the camera lens;
d6: axial distance from the image side surface of the third lens L3 to the object side surface of the fourth lens L4.

Ratio of distance between the image side of the third lens L3 and object side of the fourth lens L4 to the overall focal distance of the camera lens is specified in condition (8). Moreover, the development of ultra-thin and wide angle trend of cannot be implemented easily outside the range of the condition (8).

Because five lenses of camera Lens all have the stated formation and meet all the conditions, so it is possible to produce a camera lens which is composed of five ultra-thin, wide angle lenses with excellent optional properties and with chromatic aberration sufficiently corrected.

The camera lens LA of the invention shall be explained below by using the embodiments. Moreover, the symbols used in all embodiments are shown as follows. And mm shall be taken as the units of the distance, the radius and the center thickness.

f: overall focal distance of the camera lens LA

f1: focal distance of the first lens L1

f2: focal distance of the second lens L2

f3: focal distance of the third lens L3

f4: focal distance of the fourth lens L4

f5: focal distance of the fifth lens L5

Fno: F value

2ω: total angle of view

R: curvature radius of optical surface, central curvature radius when the lens is involved

R1: curvature radius of the first lens L1's object side surface

R2: curvature radius of the first lens L1's image side surface

R3: curvature radius of the second lens L2's object side surface

R4: curvature radius of the second lens L2's image side surface

R5: curvature radius of the third lens L3's object side surface

R6: curvature radius of the third lens L3's image side surface

R7: curvature radius of the fourth lens L4's object side surface

R8: curvature radius of the fourth lens L4's image side surface

R9: curvature radius of the fifth lens L5's object side surface

R10: curvature radius of the fifth lens L5's image side surface

R11: curvature radius of the glass plate GF's object side surface

R12: curvature radius of the glass plate GF's image side surface

d: center thickness of lenses or the distance between lenses

d0: distance from the open aperture S1 to the object side surface of the first lens L1

d1: center thickness of the first lens L1

d2: distance from the image side surface of the first lens L1 to the object side surface of the second lens L2

d3: center thickness of the second lens L2

d4: axial distance from the image side surface of the second lens L2 to the object side surface of the third lens L3

d5: center thickness of the third lens L3

d6: axial distance from the image side surface of the third lens L3 to the object side surface of the fourth lens L4

d7: center thickness of the fourth lens L4

d8: axial distance from the image side surface of the fourth lens L4 to the object side surface of the fifth lens L5

d9: center thickness of the fifth lens L5

d14: axial distance from the image side surface of the fifth lens L5 to the object side surface of the glass plate GF

d11: center thickness of the glass plate GF

d12: axial distance from the image side surface to the imaging surface of the glass plate GF

nd: refractive power of line d

nd1: refractive power of line d of the first lens L1

nd2: refractive power of line d of the second lens L2

nd3: refractive power of line d of the third lens L3

nd4: refractive power of line d of the fourth lens L4

nd5: refractive power of line d of the fifth lens L5

nd6: refractive power of line d of the glass plate GF

ν1: abbe number of the first lens L1

ν2: abbe number of the second lens L2

ν3: abbe number of the third lens L3

ν4: abbe number of the fourth lens L4

ν5: abbe number of the fifth lens L5

ν6: abbe number of the glass plate GF

TTL: optical length (axial distance from object side surface to the imaging surface of the first lens L1)

LB: axial distance (including the thickness of the glass plate GF) from the image side surface to the imaging surface of the fifth lens L5;

For convenience sake, the aspheric surface shown in the formula (9) shall be taken as the aspheric surfaces of all lens surfaces. However, the invention shall be not limited to the polynomial form of the aspheric surface shown in the formula (9).

The configuration structure diagram of the camera lens LA in the Embodiment 1 is shown in theFIG. 2. Moreover, the data including curvature radius R of the object side surfaces and the image side surfaces, center thicknesses of the lenses, the distances d among the lenses, refractive powers nd and abbe numbers v d of the lens L1-L5 in the Embodiment 1 are shown in the Table 1, wherein the camera lens LA is formed by the lens L1-L5; and the data including conic coefficients k and aspheric coefficients are shown in the Table 2.

The values in the embodiments 1 and 2 and the values corresponding to the parameters specified in the conditions (1)-(8) are shown in the subsequent Table 5.

The Embodiment 1 meets the conditions (1)-(8), as shown in Table 5.

SeeFIG. 3for Longitudinal Aberration of the camera lens LA in the Embodiment 1, seeFIG. 4for Lateral Color Aberration of it, and seeFIG. 5for curvature of field and distortion of it. Further, the curvature of field S in theFIG. 5is the one in the sagittal direction, and T is the one in the direction of meridian, as well as in the Embodiment 2. As shown inFIGS. 3˜5, the camera lens in embodiment 1 has 2ω=82.7°, TTL/IH=1.360 and is aso wide angle and ultra-thin, it is no wonder why chromatic aberration on axle and outside of axle is sufficiently corrected and why it has excellent optical properties.

The configuration structure diagram of the camera lens LA in the Embodiment 2 is shown in theFIG. 6. Moreover, the curvature radius of the object side surfaces and the image side surfaces, the center thicknesses of the lenses, the distances d among the lenses, the refractive powers nd and abbe numbers vd of the lens L1-L5 in the Embodiment 2 are shown in the Table 3, wherein the camera lens LA is formed by the lens L1-L5; and the conical coefficients k and aspheric coefficients are shown in the Table 4.

The Embodiment 2 meets the conditions (1)-(8), as shown in Table 5.

SeeFIG. 7for Longitudinal Aberration of the camera lens LA in the Embodiment 2, seeFIG. 8for Lateral Color Aberration of it, and seeFIG. 9for curvature of field and distortion of it. As shown inFIGS. 7˜9, the camera lens in embodiment 2 has 2ω=78.9°, TTL/IH=1.400 and is also wide angle and ultra-thin, it is no wonder why chromatic aberration on axle and outside of axle is sufficiently corrected and why it has excellent optical properties.

The values in all embodiments and the values corresponding to the parameters specified in the conditions (1)-(8) are shown in the Table 5. Moreover, the units including 2ω(°), f (mm), f1 (mm), f2 (mm), f3 (mm), f4 (mm), f5 (mm), \TTL (mm), LB (mm) and IH (mm) are shown in the Table 5, respectively.