Camera lens

A camera lens is disclosed. The camera lens comprises, from an object side to an image side, 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 negative refractive power; a fifth lens with positive refractive power; and a sixth lens with negative refractive power. 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.

A related camera lens is composed of six piece lenses which are arranged sequentially from the 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 negative refractive power and a fifth lens with positive refractive power; a sixth lens with negative refractive power

The camera lens disclosed in embodiments 4, 7 of the prior reference document 1 is composed of above mentioned six piece lenses, but the shape of the first lens and the third lens is improper; therefore Fno 2.19 and 2.14 brightness is not sufficient.

The camera lens disclosed in embodiment 3 of the prior reference document 2 is composed of above mentioned six piece lenses, Fno=1.85 high-luminous flux, but the shape of the first lens and the third lens is improper; so it is not sufficiently ultra-thin.

PRIOR REFERENCE DOCUMENTS

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Referring toFIG. 1, a camera lens LA comprises, in an order from an object side to an imaging side, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5and a sixth lens L6. A glass plate GF is arranged between the sixth lens L6and 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 feasible if no glass plate GF is arranged between the sixth lens L6and 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 negative refractive power; the fifth lens has positive refractive power; and the sixth lens has negative refractive power. Moreover, the surfaces of the six lenses should be designed as the aspheric shape preferably in order to correct the aberration well.

The camera lens LA meets the following conditions (1)˜(3):
1.80≦f3/f≦5.00   (1);
0.15≦R1/R2≦0.30   (2);
18.00≦R5/R6   (3); where,f: overall focal distance of the camera lens;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;R5: the curvature radius of the third lens L3's object side surface;R6: the curvature radius of the third lens L3's image side surface.

The positive refractive power of the third lens L3is specified in the condition (1). Moreover, the development of ultra-thin and wide angle trend of Fno≦2.0 cannot be implemented easily outside the range of the condition (1).

Therefore, numerical range of condition (1) should be set within the numerical range of the following condition (1-A) preferably,
2.20≦f3/f≦3.50   (1-A)o

The shape of the first lens L1is specified in the condition (2). Moreover, the development toward Fno≦2.0 cannot be implemented easily outside the range of the condition (2).

Therefore, the ranges of the values in the Condition (2) should be set within the numerical range of the following condition (2-A) preferably,
0.18≦R1/R2≦0.26   (2-A)

The shape of the third lens L3is specified in the condition (3). Moreover, the development of ultra-thin and wide angle trend of Fno≦2.0 cannot be implemented easily 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,
20.00≦R5/R6≦100.00   (3-A)

The first lens L1has positive refractive power and meets the following condition (4).
0.75f1/f≦1.00   (4); where,f: overall focal distance of the camera lens;f3: focal distance of the first lens L1.

The positive refractive power of the first lens L1is specified in the condition (4). It is useful for development of ultra-thin trend when the numerical range exceeds the lower limit specified in the condition (4); however, the aberration cannot be corrected easily because the positive refractive power of the first lens L1becomes 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 positive refractive power of the first lens L1becomes too weak

Therefore, the numerical ranges of condition (4) should be set within the numerical range of the following condition (4-A) preferably,
0.80≦f1/f≦0.95   (4-A)o

The second lens L2has negative refractive power and meets following condition (5).
1.00≦R3/R4≦3.00   (5); where,R3: curvature radius of the second lens L2's object side surface;R4: curvature radius of the second lens L2's image side surface.

Shape of the second lens L2is specified in the condition (5). Moreover, the problems, such as correction of chromatic aberration on axle, etc. cannot be implemented easily along development of ultra-thin and wide angle trend of Fno≦2.0 outside the range of the condition (5)

Therefore, the numerical range of the condition (5) should be set within the numerical range of the following condition (5-A) preferably,
1.50≦R3/R4≦2.80   (5-A)

Because 6 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 6 lenses with excellent optional properties, TTL(optical length)/IH(image height)≦1.45, ultrathin, wide angle 2ω≧76°, Fno≦2.0

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 LAf1: 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.f6: focal distance of the sixth lens L6.Fno: F value;2ω: total angle of view;S1: aperture;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 surfaceR2: curvature radius of the first lens L1's image side surfaceR3: curvature radius of the second lens L2's object side surfaceR4: curvature radius of the second lens L2's image side surfaceR5: curvature radius of the third lens L3's object side surfaceR6: curvature radius of the third lens L3's image side surfaceR7: curvature radius of the fourth lens L4's object side surfaceR8: curvature radius of the fourth lens L4's image side surfaceR9: curvature radius of the fifth lens L5's object side surfaceR10: curvature radius of the fifth lens L5's image side surfaceR11: curvature radius of the sixth lens L6's object side surfaceR12: curvature radius of the sixth lens L6's image side surfaceR13: curvature radius of the glass plate GF's object side surfaceR14: curvature radius of the glass plate GF's image side surfaced: center thickness of lenses or the distance between lensesd0: distance from the open aperture S1to the object side of the first lens L1d1: center thickness of the first lens L1d2: distance from the image side surface of the first lens L1to the object side surface of the second lens L2d3: center thickness of the second lens L2d4: axial distance from the image side surface of the second lens L2to the object side surface of the third lens L3d5: center thickness of the third lens L3d6: axial distance from the image side surface of the third lens L3to the object side surface of the fourth lens L4d7: center thickness of the fourth lens L4d8: axial distance from the image side surface of the fourth lens L4to the object side surface of the fifth lens L5d9: center thickness of the fifth lens L5d10: axial distance from the image side surface of the fifth lens L5to the object side surface of the sixth lens L6d11: center thickness of the sixth lens L6d12: axial distance from the image side surface of the sixth lens L6to the object side surface of the glass plate GFd13: center thickness of the glass plate GFd14: axial distance from the image side surface to the imaging surface of the glass plate GFnd: refractive power of line dnd1: refractive power of line d of the first lens L1nd2: refractive power of line d of the second lens L2nd3: refractive power of line d of the third lens L3nd4: refractive power of line d of the fourth lens L4nd5: refractive power of line d of the fifth lens L5nd6: refractive power of line d of the sixth lens L6nd7: refractive power of line d of the glass plate GFνd: abbe numberν1: abbe number of the first lens L1ν2: abbe number of the second lens L2ν3: abbe number of the third lens L3ν4: abbe number of the fourth lens L4ν5: abbe number of the fifth lens L5ν6: abbe number of the sixth lens L6ν7: abbe number of the glass plate GFTTL: 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 sixth lens L6;νIH: image height
y=(x2/R)/[1+{1−(k+1)(x2/R2)}1/2]+A4×4+A6×6+A8×8+A10×10+A12×12+A14×14+A16×16 (6);
where R indicates the curvature radius on the axle; k indicates the conical coefficient; and A4, A6, A8, A10, A12, A14 and A16 indicates the coefficients of the aspheric surface.

For convenience sake, the aspheric surface shown in the formula (6) 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 (6).

The configuration structure diagram of the camera lens LA in the Embodiment 1 is shown inFIG. 2. Moreover, the data including curvature radius of the object side surfaces and the imaging side surfaces, the center thicknesses of the lenses, the distances d among the lenses, refractive powers nd and abbe numbers of the lens L1-L6in the Embodiment 1 are shown in Table 1, wherein the camera lens LA is formed by the lens L1-L6; and the data including conical coefficients k and aspheric coefficients are shown in Table 2.

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

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

Refer toFIG. 3for Longitudinal Aberration of the camera lens LA in the Embodiment 1, refer toFIG. 4for Lateral Color Aberration of it, and refer toFIG. 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. Moreover, the camera lens LA in the embodiment 1 involves the ultra-thin wide angle camera lens having high luminous flux as shown inFIGS. 3-5, wherein 2ω=80.2°, TTL/IH=1.420, Fno=1.90; therefore, it is no wonder that this lens has these 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, refractive powers nd and abbe numbers νd of the lens L1-L6in the Embodiment 2 are shown in Table 3, wherein the camera lens LA is formed by the lens L1-L6; and the conical coefficients k and aspheric coefficients are shown in Table 4.

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

Refer toFIG. 7for Longitudinal Aberration diagram of the camera lens LA in the Embodiment 2, refer toFIG. 8for Lateral Color Aberration of it, and refer toFIG. 9for curvature of field and distortion of it. Moreover, the total angle of view is involved in the camera lens LA in the Embodiment 2 as shown inFIGS. 7-9, and the lens refers to the ultra-thin wide-angle camera lens having high luminous flux, wherein 2ω=80.2°, TTL/IH=1.42, Fno=1.90; therefore, it is no wonder that this lens has these excellent optical properties.

The values in all embodiments and the values corresponding to the parameters specified in the conditions (1)-(5) are shown in the Table 5. Moreover, the units including 2ω(°), f(mm), f1(mm), f2(mm), f3(mm), f4(mm), f5(mm), f6(mm), TTL(mm), LB(mm) and IH(mm) are shown in the Table 5, respectively.