# Patent

## Title
Imaging lens assembly

## Abstract

An imaging lens assembly is provided in the present disclosure. The imaging lens assembly includes a first lens with positive refractive power; a second lens with negative refractive power; a third lens with negative refractive power; a fourth lens with positive or negative refractive power; a fifth lens with positive refractive power; and a sixth lens with negative refractive power. The first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens are arranged in sequence from the object side to the image side, and satisfy conditions provided in the present disclosure.

## Background
FIELD OF THE DISCLOSURE
The present disclosure relates to optical technologies, and more particular, to an imaging lens assembly applicable to a digital camera of a mobile phone or a WEB camera, which uses CCD imaging components or CMOS imaging components with high resolution.
BACKGROUND
CCD imaging components and CMOS imaging components are used widely in camera device, to meet the requirements of miniaturization and good performance of the imaging components, a wide-angle lens assembly with good optical characteristic, thin profile, and high luminous flux (namely, F number) is needed.
Japanese patent No. 5651881 discloses an imaging lens assembly including six lenses. However, a proportion of a total track length (TTL) and an image height (IH) of the imaging lens assembly is greater than 1.46; this is, TTL/IH≧1.46. Accordingly, the imaging lens assembly is too thick to meet the miniaturization requirement.
Accordingly, an improved imaging lens assembly which can overcome the disadvantages described above is desired.



BRIEF DESCRIPTION OF THE DRAWINGS
Many aspects of the embodiment can be better understood with reference to the following drawings. The components in the drawing are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.
FIG. 1 is a schematic view of an imaging lens assembly according to an embodiment of the present disclosure, with parameter symbols labeled thereon;
FIG. 2 schematically illustrates an imaging lens assembly according to the first exemplified embodiment;
FIG. 3 schematically illustrates the longitudinal aberration of the imaging lens assembly of FIG. 2;
FIG. 4 schematically illustrates the lateral color of the imaging lens assembly of FIG. 2;
FIG. 5 schematically illustrates the field curvature and distortion of the imaging lens assembly of FIG. 2;
FIG. 6 schematically illustrates an imaging lens assembly according to the second exemplified embodiment;
FIG. 7 schematically illustrates the longitudinal aberration of the imaging lens assembly of FIG. 6;
FIG. 8 schematically illustrates the Lateral color of the imaging lens assembly of FIG. 6;
FIG. 9 schematically illustrates the field curvature and distortion of the imaging lens assembly of FIG. 6.



DETAILED DESCRIPTION
The present invention will hereinafter be described in detail with reference to several embodiments.
Referring to FIG. 1, an imaging lens assembly LA according to an embodiment of the present disclosure is shown. The imaging lens assembly LA includes a lens set with six lenses, that is, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5 and a sixth lens L6, which are arranged in that order from the object side to the image plane. A glass filter GF is arranged between the sixth lens L6 and the image plane. The glass filter GF may be a cover glass or an IR filter. Alternatively, the glass filter GF may be arranged in other location or even removed from the imaging lens assembly LA.
The first lens L1 has a positive refractive power, the second lens L2 has a negative refractive power, the third lens L3 also has a negative refractive power, the fourth lens L4 may have a positive or negative refractive power, the fifth lens L5 has a positive refractive power, and the sixth lens L6 has a negative refractive power. In practice, the six lenses L1 to L6 may be designed to have aspheric surfaces, so as to compensate aberration in the imaging lens assembly LA.
The imaging lens assembly LA satisfies the following conditions (1) to (4):

0.60≦f1/f≦0.80  (1)

−2.00≦(R1+R2)/(R1−R2)≦−1.10  (2)

1.15≦(R3+R4)/(R3−R4)≦1.40  (3)

−7.50≦(R5+R6)/(R5−R6)≦−3.00  (4)

Where:
f is the focal length of the imaging lens assembly LA;
f1 is the focal length of the first lens L1;
R1 is the curvature radius of the object side of the first lens L1;
R2 is the curvature radius of the image side of the first lens L1;
R3 is the curvature radius of the object side of the second lens L2;
R4 is the curvature radius of the image side of the second lens L2;
R5 is the curvature radius of the object side of the third lens L3; and
R6 is the curvature radius of the image side of the third lens L3.
The condition (1) defines the positive refractive power of the first lens L1. If the value excesses the minimum limit, it is better for the miniaturization of the imaging lens assembly LA; however, the positive refractive power of the first lens L1 is too strong to compensate aberration. In contrast, if the value excesses the maximum limit, the positive refractive power of the first lens L1 is too weak, and is adverse to the miniaturization of the imaging lens assembly LA.
In addition, the proportion value f1/f in condition (1) is preferred to be set in the value range as defined in the following condition (1-A):

0.66≦f1/f≦0.80  (1-A)

The condition (2) defines the shape of the first lens L1. If the proportion value (R1+R2)/(R1−R2) is beyond the value range defined by condition (2), it is difficult to compensate high order aberration such as the spherical aberration when the imaging lens assembly LA has a less thickness and a wider view angle with an F number (Fno) less than 2.2.
In addition, the proportion value (R1+R2)/(R1−R2) in condition (2) is preferred to be set in the value range as defined in the following condition (2-A):

−1.80≦(R1+R2)/(R1−R2)≦−1.10  (2-A)

The condition (3) defines the shape of the second lens L2. If the proportion value (R3+R4)/(R3−R4) is beyond the value range defined by condition (3), it is difficult to compensate the on-axis chromatic aberration when the imaging lens assembly LA has a less thickness and a wider view angle with an F number (Fno) less than 2.2.
In addition, the proportion value (R3+R4)/(R3−R4) in condition (3) is preferred to be set in the value range as defined in the following condition (3-A):

1.17≦(R3+R4)/(R3−R4)≦1.38  (3-A)

The condition (4) defines the shape of the third lens L3. If the proportion value (R5+R6)/(R5−R6) is beyond the value range defined by condition (4), it is difficult to compensate the Lateral Color when the imaging lens assembly LA has a less thickness and a wider view angle with an F number (Fno) less than 2.2. In addition, the proportion value (R5+R6)/(R5−R6) in condition (4) is preferred to be set in the value range as defined in the following condition (4-A):

−6.50≦(R5+R6)/(R5−R6)≦−3.50  (4-A)

The second lens L2 may have a negative refractive power, which satisfies the following condition (5):

−2.00≦f2/f≦−1.00  (5)

In the above condition (5),
f is the focal length of the imaging lens assembly; and
f2 is the focal length of the second lens L2.
The condition (5) defines the negative refractive power of the second lens L2. If the proportion value f2/f is beyond the value range defined by condition (5), it is difficult to compensate the on-axis chromatic aberration when the imaging lens assembly LA has a less thickness and a wider view angle with an F number (Fno) less than 2.2.
Upon the condition that the six lenses L1 to L6 satisfy the aforesaid conditions, the imaging lens assembly LA is possible to have good optical characteristic as well as an ultra-thin profile, and moreover, the imaging lens assembly LA may also satisfy the following parameter requirements: TTL/IH≦1.35, view angle 2ω≧76°, and Fno≦2.2.
The following description describes the imaging lens assembly LA according to the present disclosure in detail with reference to several embodiments; parameters of the imaging lens assembly LA are defined as follows, in which the unit of each of distance, radius, and central thickness is millimeter (mm):
f: the focal length of the imaging lens assembly LA;
f1: the focal length of the first lens L1;
f2: the focal length of the second lens L2;
f3: the focal length of the third lens L3;
f4: the focal length of the fourth lens L4;
f5: the focal length of the fifth lens L5;
f6: the focal length of the sixth lens L6;
Fno: F-number; 2ω: full view angle;
S1: aperture stop;
R: the curvature radius of an optical surface, and may also be the central curvature radius of the lens;
R1: the curvature radius of the object side of the first lens L1;
R2: the curvature radius of the image side of the first lens L1;
R3: the curvature radius of the object side of the second lens L2;
R4: the curvature radius of the image side of the second lens L2;
R5: the curvature radius of the object side of the third lens L3;
R6: the curvature radius of the image side of the third lens L3;
R7: the curvature radius of the object side of the fourth lens L4;
R8: the curvature radius of the image side of the fourth lens L4;
R9: the curvature radius of the object side of the fifth lens L5;
R10: the curvature radius of the image side of the fifth lens L5;
R11: the curvature radius of the object side of the sixth lens L6;
R12: the curvature radius of the image side of the sixth lens L6;
R13: the curvature radius of the object side of the glass filter GF;
R14: the curvature radius of the image side of the glass filter GF;
d: an axial thickness of the lens or an axial distance between lenses;
d0: the axial distance between the aperture stop and the object side of the first lens L1;
d1: the central thickness of the first lens L1;
d2: the axial distance between the image side of the first lens L1 and the object side of the second lens L2;
d3: the central thickness of the second lens L2;
d4: the axial distance between the image side of the second lens L2 and the object side of the third lens L3;
d5: the central thickness of the third lens L3;
d6: the axial distance between the image side of the third lens L3 and the object side of the fourth lens L4;
d7: the central thickness of the fourth lens L4;
d8: the axial distance between the image side of the fourth lens L4 and the object side of the fifth lens L5;
d9: the central thickness of the fifth lens L5;
d10: the axial distance between the image side of the fifth lens L5 and the object side of the sixth lens L6;
d11: the central thickness of the sixth lens L6;
d12: the axial distance between the image side of the sixth lens L6 and the object side of the glass filter GF;
d13: the central thickness of the glass filter GF;
d14: the axial distance between the image side of the glass filter GF and the image plane;
nd: d line refraction index;
nd1: d line refraction index of the first lens L1;
nd2: d line refraction index of the second lens L2;
nd3: d line refraction index of the third lens L3;
nd4: d line refraction index of the fourth lens L4;
nd5: d line refraction index of the fifth lens L5;
nd6: d line refraction index of the sixth lens L6;
nd7: d line refraction index of the glass filter GF;
νd: abbe number (i.e., dispersion coefficient)
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 sixth lens L6;
ν7: abbe number of the glass plate GF;
TTL: the total track length (i.e., an axial distance between the object side of the first lens L1 and the image plane);
LB: the axial distance between the image side of the second lens L6 and the image plane (including a thickness of the glass plate GF); and
IH: the image height.

y=(x2/R)/[1+{1−(k+1)(x2/R2)}1/2]+A4x4+A6x6+A8x8+A10x10+A12x12+A14x14+A16x16  (6)

In the above condition (6), R refers to an axial curvature radius, k refers to a conic coefficient, and A4, A6, A8, A10, A12, A14 and A16 are aspherical coefficients.
Optionally, aspherical surfaces of the lenses L1-L6 may be obtained according to condition (6); alternatively, the aspherical surfaces may also be obtained according to other conditions.
Embodiment 1
FIG. 2 illustrated an imaging lens assembly LA in accordance with the first exemplified embodiment of the present disclosure. TABLE 1 and TABLE 2 show the detailed optical data of the imaging lens assembly LA.
The optical data in TABLE 1 includes the curvature radius R, the axial thickness d, the axial distance between lenses d, refraction index nd and abbe number νd of the lenses L1 to L6 in the imaging lens assembly LA. The optical data in TABLE 2 includes conic coefficient (C-coefficient) k and aspherical coefficient of the lenses L1 to L6 in the imaging lens assembly LA.











TABLE 1






R
d
nd
νd






















S1
∞
d0 =
−0.310






R1
1.53995
d1 =
  0.586
nd1
1.5441
ν1
56.12


R2
22.07678
d2 =
  0.058






R3
37.19457
d3 =
  0.243
nd2
1.6448
ν2
22.44


R4
3.38460
d4 =
  0.373






R5
−58.09431
d5 =
  0.238
nd3
1.6397
ν3
23.53


R6
−92.35499
d6 =
  0.080






R7
4.91476
d7 =
  0.366
nd4
1.5441
ν4
56.12


R8
5.21559
d8 =
  0.366






R9
−7.46637
d9 =
  0.519
nd5
1.5352
ν5
56.12


R10
−1.31277
d10 =
  0.510






R11
−2.88094
d11 =
  0.418
nd6
1.5352
ν6
56.12


R12
2.42017
d12 =
  0.520






R13
∞
d13 =
  0.210
nd7
1.5168
ν6
64.17


R14
∞
d14 =
  0.189


















TABLE 2








C-coefficient
aspherical coefficient
















k
A4
A6
A8
A10
A12
A14
A16


















R1
−3.3341E−01
1.3666E−03
2.9702E−02
−2.1774E−02
−9.3438E−03
1.5200E−02
1.3663E−02
−2.5549E−02


R2
0.0000E+00
−2.5760E−02
1.4567E−02
3.6346E−02
−3.8835E−02
−5.7498E−02
2.4410E−03
3.5800E−02


R3
−1.3537E+03
−9.8237E−03
3.2261E−02
2.2134E−02
6.4311E−04
−4.2221E−02
−7.0047E−02
9.4446E−02


R4
−2.9129E+00
2.4410E−02
8.8216E−03
9.4199E−02
3.1828E−02
−1.0801E−01
−1.3076E−01
1.9366E−01


R5
−4.4128E+02
−2.3399E−02
−6.2691E−02
−2.9843E−02
3.2513E−02
4.9103E−02
2.2515E−02
−5.1583E−02


R6
4.8417E+03
−2.6769E−02
−7.1330E−02
5.2181E−03
3.6132E−02
2.1292E−02
−2.2877E−04
−1.1071E−02


R7
0.0000E+00
−1.3306E−01
1.0505E−02
1.0562E−02
5.7542E−03
2.2628E−03
−4.7011E−04
−1.2293E−03


R8
0.0000E+00
−1.0952E−01
1.2147E−02
4.9050E−03
−1.6616E−03
−8.6107E−04
7.5762E−05
1.4271E−04


R9
7.3469E+00
−1.8669E−02
−1.2579E−02
2.0484E−03
−1.7373E−03
9.7874E−05
1.9435E−04
1.2021E−05


R10
−3.7865E+00
−3.5819E−02
1.7662E−02
−1.1281E−03
−6.2566E−05
−7.5645E−05
−4.2074E−06
2.8034E−06


R11
0.0000E+00
−2.2345E−05
4.0238E−03
5.8035E−05
−2.8897E−05
−2.0160E−06
5.9500E−08
4.9453E−08


R12
−1.9599E+01
−2.7118E−02
4.0662E−03
−7.5953E−04
3.2209E−05
1.5758E−06
6.4623E−08
2.7787E−09









The relevant optical data of the imaging lens assembly LA in the first embodiment and the values defined in the aforesaid conditions (1) to (5) are shown in TABLE 5 as provided in the subsequent paragraphs.
As can be seen in TABLE 5, the imaging lens assembly LA in the first embodiment satisfies the aforesaid conditions (1) to (5).
FIGS. 3-5 schematically illustrate the longitudinal aberration, the lateral color, the field curvature and distortion of the imaging lens assembly LA as provided in the first embodiment respectively. In FIG. 5, curve S represents the field curvature related to the sagittal plane, and curve T represents the field curvature related to the tangential plane.
As can be seen, in the first embodiment, the view angle 2ω of the imaging lens assembly LA is 82.8°, the proportion value TTL/IH of the imaging lens assembly LA is 1.346, and the F number is 2.05. In other words, the imaging lens assembly LA as provided in the first embodiment has an ultra-thin profile and a wide-angle with high luminous flux, and accordingly has good optical characteristics.
Embodiment 2
FIG. 6 illustrated an imaging lens assembly LA in accordance with the second embodiment of the present disclosure. TABLE 3 and TABLE 4 show the detailed optical data of the imaging lens assembly LA.
The optical data in TABLE 3 includes the curvature radius R, the axial thickness d, the axial distance between lenses d, refraction index nd and abbe number νd of the lenses L1 to L6 in the imaging lens assembly LA. The optical data in TABLE 4 includes conic coefficient (C-coefficient) k and aspherical coefficient of the lenses L1 to L6 in the imaging lens assembly LA.











TABLE 3






R
d
nd
νd






















S1
∞
d0 =
−0.310






R1
1.51908
d1 =
  0.600
nd1
1.5441
ν1
56.12


R2
14.33117
d2 =
  0.059






R3
34.18880
d3 =
  0.240
nd2
1.6448
ν2
22.44


R4
3.47890
d4 =
  0.377






R5
−61.38130
d5 =
  0.242
nd3
1.6397
ν3
23.53


R6
−96.57146
d6 =
  0.078






R7
4.91934
d7 =
  0.372
nd4
1.5441
ν4
56.12


R8
5.17762
d8 =
  0.373






R9
−7.49478
d9 =
  0.512
nd5
1.5352
ν5
56.12


R10
−1.31517
d10 =
  0.506






R11
−2.87700
d11 =
  0.414
nd6
1.5352
ν6
56.12


R12
2.41807
d12 =
  0.520






R13
∞
d13 =
  0.210
nd7
1.5168
ν6
64.17


R14
∞
d14 =
  0.179


















TABLE 4








C-coefficient
aspherical coefficient
















k
A4
A6
A8
A10
A12
A14
A16


















R1
−4.0088E−01
−3.6777E−03
2.8909E−02
−2.1526E−02
−9.0835E−03
1.5311E−02
1.3637E−02
−2.5670E−02


R2
0.0000E+00
−3.7770E−02
1.0818E−02
3.5228E−02
−3.8826E−02
−5.6957E−02
3.2369E−03
3.6712E−02


R3
1.6578E+01
−8.8559E−03
3.1152E−02
2.1504E−02
1.9774E−04
−4.2649E−02
−7.0497E−02
9.3977E−02


R4
−2.4633E+00
2.7059E−02
2.1201E−02
9.8279E−02
3.1597E−02
−1.0982E−01
−1.3285E−01
1.9187E−01


R5
−7.6696E+03
−2.0749E−02
−6.0434E−02
−2.9271E−02
3.2567E−02
4.9881E−02
2.4601E−02
−4.7741E−02


R6
5.0291E+03
−2.6963E−02
−7.2019E−02
4.9280E−03
3.6069E−02
2.1300E−02
−1.8706E−04
−1.1035E−02


R7
0.0000E+00
−1.3337E−01
1.0544E−02
1.0671E−02
5.8292E−03
2.3010E−03
−4.5915E−04
−1.2376E−03


R8
0.0000E+00
−1.0851E−01
1.2129E−02
4.7722E−03
−1.7231E−03
−8.8050E−04
7.1875E−05
1.4344E−04


R9
7.7607E+00
−1.8893E−02
−1.2732E−02
1.9952E−03
−1.7485E−03
9.3804E−05
1.9170E−04
1.0511E−05


R10
−3.7863E+00
−3.5794E−02
1.7648E−02
−1.1418E−03
−6.7872E−05
−7.6966E−05
−4.3165E−06
2.9216E−06


R11
0.0000E+00
−9.3462E−05
4.0190E−03
5.7923E−05
−2.8853E−05
−2.0041E−06
6.2658E−08
5.0407E−08


R12
−2.0452E+01
−2.7121E−02
4.0868E−03
−7.5667E−04
3.2432E−05
1.5889E−06
6.4978E−08
2.6980E−09









The relevant optical data of the imaging lens assembly LA in the second embodiment and the values defined in the aforesaid conditions (1) to (5) are shown in TABLE 5 as provided in the subsequent paragraphs. As can be seen in TABLE 5, the imaging lens assembly LA in the second embodiment satisfies the aforesaid conditions (1) to (5).
FIGS. 7-9 schematically illustrate the longitudinal aberration, the lateral color, the field curvature and distortion of the imaging lens assembly LA as provided in the second exemplified embodiment respectively. In FIG. 9, curve S represents the field curvature related to the sagittal plane, and curve T represents the field curvature related to the tangential plane.
As can be seen, in the second exemplified embodiment, the view angle 2ω of the imaging lens assembly LA is 82.6°, the proportion value TTL/IH of the imaging lens assembly LA is 1.347, and the F number is 2.05. In other words, the imaging lens assembly LA as provided in the second embodiment has an ultra-thin profile and a wide-angle with high luminous flux, and accordingly has good optical characteristics.
TABLE 5 shows the values of the imaging lens assembly LA in relevant to the conditions (1) to (5) according to both the first embodiment and the second embodiment. Moreover, in TABLE 5, the unit of the value 2ω is degree (°), and the units of the values f, f1, f2, f3, f4, f5, f6, TTL, LB and IH are millimeter (mm).











TABLE 5







Embodiment 1
Embodiment 2
Formulae



















f1/f
0.78
0.79
Formula (1)


(R1 + R2)/(R1 − R2)
−1.15
−1.24
Formula (2)


(R3 + R4)/(R3 − R4)
1.20
1.23
Formula (3)


(R5 + R6)/(R5 − R6)
−4.39
−4.49
Formula (4)


f2/f
−1.49
−1.54
Formula (5)


Fno
2.05
2.05


2ω
82.8
82.6


TTL/IH
1.346
1.347


f
3.874
3.906


f1
3.012
3.072


f2
−5.791
−6.025


f3
−245.459
−264.018


f4
109.613
120.227


f5
2.891
2.897


f6
−2.392
−2.390


TTL
4.676
4.682


LB
0.919
0.909


IH
3.475
3.475









In summary, the imaging lens assembly LA as provided in the present disclosure has good optical characteristic, high luminous flux as well as an ultra-thin profile, and moreover, the imaging lens assembly LA satisfies the following parameter requirements: TTL/IH≦1.35, view angle 2ω≧76°, and Fno≦2.2. Therefore, the imaging lens assembly LA is applicable to a digital camera of a mobile phone or a WEB camera, which uses CCD imaging components or CMOS imaging components with high resolution.
It is to be understood, however, that even though numerous characteristics and advantages of the present embodiment have been set forth in the foregoing description, together with details of the structures and functions of the embodiment, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.

## Claims

1. An imaging lens assembly, comprising:
a first lens with positive refractive power;
a second lens with negative refractive power;
a third lens with negative refractive power;
a fourth lens with positive or negative refractive power;
a fifth lens with positive refractive power; and
a sixth lens with negative refractive power;
wherein the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens are arranged in sequence from the object side to the image side, and satisfy the following conditions (1) to (4):


0.60≦f1/f≦0.80  (1)



−2.00≦(R1+R2)/(R1−R2)≦−1.10  (2)



1.15≦(R3+R4)/(R3−R4)≦1.40  (3)



−7.50≦(R5+R6)/(R5−R6)≦−3.00  (4)


wherein f is the focal length of the imaging lens assembly; f1 is the focal length of the first lens; R1 is the curvature radius of the object side of the first lens; R2 is the curvature radius of the image side of the first lens; R3 is the curvature radius of the object side of the second lens; R4 is the curvature radius of the image side of the second lens; R5 is the curvature radius of the object side of the third lens; R6 is the curvature radius of the image side of the third lens.

2. The imaging lens assembly of claim 1, further satisfying the following condition (5):


−2.00≦f2/f≦−1.00  (5)

wherein f is the focal length of the imaging lens assembly, and f2 is the focal length of the second lens.