Miniature digital camera lens
View Patent ↗Miniature camera lenses ( 100, 300 ) include in order an object side ( 116, 302 ) to the image side ( 118, 304 ) a first double concave lens ( 102, 306 ), a lens group including first convergent meniscus lens ( 104, 318 ), a first double convex lens ( 106, 312 ), a second convergent meniscus lens ( 108, 318 ), a second double concave lens ( 110, 330 ), a second double convex lens ( 112, 336 ), and a divergent meniscus lens ( 114, 342 ). The lenses ( 100, 300 ) feature a field of view of about fifty six degrees, low distortion, a relatively long back focal distance, and a relatively low F-number.
1. A fixed focal length digital camera lens comprising
a first lens group facing an object side with all of the lenses therein having only spherical surfaces, wherein said first lens group has at least three lenses with a first composite focal length F 1 ;
a second lens group facing an image side with all of the lenses therein having only spherical surfaces, said second lens group being optically coupled to said first lens group, wherein said second lens group has at least three lenses with a second composite focal length F 2 , and
wherein said first lens group and said second lens group alone provide a fixed third focal length F of the fixed focal length digital camera lens, wherein said first composite focal length F 1 , said second composite focal length F 2 , and said fixed third focal length F satisfy the following inequality relations:
0.277< F/F 1<0.308
0.457< F/F 2<0.537
and wherein the fixed focal length digital camera lens has a fixed third focal length F to back focal distance BFD ratio that satisfies the following inequality relation:
BFD/F< 0.6.
2. The fixed focal length digital camera lens according to claim 1 having a focal length of 6.25 mm, an F-number of 2.8 and a field of view of fifty-six degrees.
3. The fixed focal length digital camera lens according to claim 1 wherein said second lens group comprises, in order from said first lens group to said image side:
a first convergent meniscus lens having a first convex surface facing said object side and a first concave surface facing said image side;
a first double concave lens having a second concave surface facing said object side and a third concave surface facing said image side;
a first double convex lens having a second convex surface facing said object side and a third convex surface facing said image side; and
a divergent meniscus lens having a fourth concave surface facing said object side and a fourth convex surface facing said image side.
4. The fixed focal length digital camera lens according to claim 3 wherein said first lens group comprises, in order from said object side to said second lens group:
a second double concave lens having a fifth concave surface facing said object side and a sixth concave surface facing said image side;
a second convergent meniscus lens having a seventh concave surface facing said object side and a fifth convex surface facing said image side; and
a second double convex lens having a sixth convex surface facing said object side and a seventh convex surface facing said image side.
5. The fixed focal length digital camera lens according to claim 3 wherein said first lens group comprises, in order from said object side to said second lens group:
a second double concave lens having a fifth concave surface facing said object side and a sixth concave surface facing said image side;
a second double convex lens having a fifth convex surface facing said object side and a sixth convex surface facing said image side; and
a second convergent meniscus lens having a seventh concave surface facing said object side and a seventh convex surface facing said image side.
6. The fixed focal length digital camera lens according to claim 3 wherein said first double concave lens has an Abbe number less than 36.
7. A digital camera lens comprising an optical train comprising in order from an object side to an image side:
a first double concave lens having a first concave surface facing said object side and a second concave surface facing said image side;
a first convergent meniscus lens having a third concave surface facing said object side and a first convex surface facing said image side;
a first double convex lens having a second convex surface facing said object side and a third convex surface facing said image side;
a second convergent meniscus lens having a fourth convex surface facing said object side and a fourth concave surface facing said image side;
a second double concave lens having a fifth concave surface facing said object side and a sixth concave surface facing said image side;
a second double convex lens having a fifth convex surface facing said object side and a sixth convex surface facing said image side; and
a divergent meniscus lens having a seventh concave surface facing said object side and a seventh convex surface facing said image side.
8. The digital camera lens according to claim 7 further comprising:
an aperture stop disposed between said second convergent meniscus lens and said second double concave lens.
9. The digital camera lens according to claim 7 wherein:
said first through seventh concave surfaces and said first through seventh convex surfaces are spherical.
10. The digital camera lens according to claim 7 wherein said lenses have indices of refraction, measured at 587.6 nanometers, that are substantially equal to values given in a first table below wherein said lenses are listed in sequence starting from said object side:
Index of
Lens #
refraction
1
1.56882549
2
1.52249219
3
1.51111929
4
1.58312717
5
1.66679593
6
1.58312717
7
1.75499705
and said surfaces of said lenses have radii and relative offsets of intersections with an optical axis that are substantially equal to values given in a second table below, wherein said radii and said relative offsets of said intersections of said surfaces are listed in sequence starting from said object side, and wherein said digital camera lens further comprises an aperture stop having a location substantially equal to a value given in the second table:
Radius
Lens #
Surface #
(mm)
t (mm)
1
1
−9.251532
1.99778653
1
2
12.34806
0.3942978
2
3
−66.07439
0.75
2
4
−11.84029
1.752293
3
5
41.21317
0.4948125
3
6
−7.026944
0.0125
4
7
2.788804
0.8348438
4
8
33.34352
0.3137959
stop
∞
0.375866
5
9
−6.643244
0.7215
5
10
3.750318
0.4875
6
11
27.2021
0.9737813
6
12
−2.425162
0.3373188
7
13
−2.003408
0.1597998
7
14
−3.407166
4.584513
cover
15
∞
0.25
cover
16
∞.
11. The digital camera lens according to claim 7 having a focal length of 6.25 mm, an F-number of 2.8 and a field of view of fifty-six degrees.
12. The digital camera lens according to claim 10 wherein said lenses have Abbe numbers that are substantially equal to values given by a third table wherein said lenses are listed in sequence starting at said object side:
Lens #
Abbe #
1
55.9758
2
59.835
3
60.4062
4
59.4596
5
33.0550
6
59.4596
7
52.3228.
13. The digital camera lens according to claim 7 wherein said lenses have indices of refraction, measured at 587.6 nanometers, that are substantially equal to values given in a first table below wherein said lenses are listed in sequence starting from said object side:
Index of
Lens #
refraction
1
1.56882549
2
1.52249219
3
1.51111929
4
1.58312717
5
1.66679593
6
1.58312717
7
1.75499705
and said surfaces of said lenses have radii and relative offsets of intersections with an optical axis that are substantially equal to values given in a second table below, wherein said radii and said offsets of said intersections of said surfaces are listed in sequence starting from said object side, and wherein said camera lens further comprises an aperture stop having a location substantially equal to a value given in the second table:
Radius R
Lens #
Surface #
(mm)
t (mm)
1
1
−21.82299
0.02499995
1
2
6.64874
0.9645285
2
3
−121.536
1.910453
2
4
−14.59909
1.892384
3
5
19.5694
3.0000533
3
6
−8.970675
1.009468
4
7
2.810638
0.7662688
4
8
38.14589
0.1833677
stop
∞
0.3169003
5
9
−9.520424
0.6878352
5
10
3.143581
0.2380642
6
11
10.43485
1.863214
6
12
−2.849094
0.4734582
7
13
−2.256812
0.02462413
7
14
−4.03729
4.427421
cover
15
∞
0.25
cover
16
∞.
14. A digital camera lens comprising an optical train comprising in order from an object side to an image side:
a first double concave lens having a first concave surface facing said object side and a second concave surface facing said image side;
a first double convex lens having a first convex surface facing said object side and a second convex surface facing said image side;
a first convergent meniscus lens having a third concave surface facing said object side and a third convex surface facing said image side;
a second convergent meniscus lens having a fourth convex surface facing said object side and a fourth concave surface facing said image side;
a second double concave lens having a fifth concave surface facing said object side and a sixth concave surface facing said image side;
a second double convex lens having a fifth convex surface facing said object side and a sixth convex surface facing said image side; and
a divergent meniscus lens having a seventh concave surface facing said object side and a seventh convex surface facing said image side.
15. The digital camera lens according to claim 14 further comprising:
an aperture stop disposed between said second convergent meniscus lens and said second double concave lens.
16. The digital camera lens according to claim 14 wherein:
said first through seventh concave surfaces and said first through seventh convex surfaces are spherical.
17. The digital camera lens according to claim 16 wherein said lenses have indices of refraction, measured at 587.6 nanometers, that are substantially equal to values given in a first table below wherein said lenses are listed in sequence starting from said object side:
Index of
Lens #
refraction
1
1.56882549
2
1.52249219
3
1.51111929
4
1.58312717
5
1.66679593
6
1.58312717
7
1.75499705
and said surfaces of said lenses have radii and relative offsets of intersections with an optical axis that are substantially equal to values given in a second table below, wherein said radii and said relative offsets of said intersections of said surfaces are listed in sequence starting from said object side, and wherein said digital camera lens further comprises an aperture stop having a location substantially equal to a value given in the second table:
Radius R
Lens #
Surface #
(mm)
t (mm)
1
1
−74.31595
0.02000003
1
2
6.334437
1.529239
2
3
34.24003
2.657562
2
4
−10.26095
2.198213
3
5
−15.79446
4.000111
3
6
−7.088317
0.5534735
4
7
2.691467
0.8153868
4
8
11.85225
0.2786541
stop
∞
0.3478188
5
9
−10.15491
0.5895439
5
10
3.119858
0.1761461
6
11
8.264103
2.10665
6
12
−2..90191
0.3941137
7
13
−2.278478
0.01502463
7
14
−3.832201
4.567591
8
15
∞
0.25
16
∞.
18. The digital camera lens according to claim 17 wherein said lenses have Abbe numbers substantially equal to values given by a third table wherein said lenses are listed in sequence starting at said object side:
Lens #
Abbe #
1
55.9758
2
59.835
3
60.4062
4
59.4596
5
33.0550
6
59.4596
7
52.3228.
19. The digital camera lens according to claim 14 wherein said camera lens further comprises a turning mirror at said image side of said divergent meniscus lens.