US 12,078,785 B2
Imaging lens
Koji Nitta, Tokyo (JP); and Masaya Hashimoto, Fukushima (JP)
Assigned to TOKYO VISIONARY OPTICS Co., Ltd., Tokyo (JP)
Filed by TOKYO VISIONARY OPTICS CO., LTD., Tokyo (JP)
Filed on Aug. 2, 2021, as Appl. No. 17/391,829.
Application 17/391,829 is a continuation of application No. 16/895,623, filed on Jun. 8, 2020, granted, now 11,852,788.
Claims priority of application No. 2019-108019 (JP), filed on Jun. 10, 2019.
Prior Publication US 2021/0364761 A1, Nov. 25, 2021
This patent is subject to a terminal disclaimer.
Int. Cl. G02B 13/00 (2006.01); G02B 9/60 (2006.01); G02B 9/62 (2006.01); G02B 13/18 (2006.01)
CPC G02B 13/0045 (2013.01) [G02B 9/62 (2013.01); G02B 9/60 (2013.01); G02B 13/18 (2013.01)] 7 Claims
OG exemplary drawing
 
1. An imaging lens comprising, in order from an object side to an image side, a first lens with negative refractive power having an object-side surface being convex in a paraxial region, a second lens with positive refractive power in a paraxial region, a third lens with negative refractive power in a paraxial region, a fourth lens with positive refractive power in a paraxial region, a fifth lens having a flat object-side surface and a flat image-side surface that are aspheric, and a sixth lens with negative refractive power having an image-side surface being concave in a paraxial region,
wherein following conditional expressions (4), (7a), (9′) and (15) are satisfied:
−2.45<r2/r4<−0.45  (4)
19<vd6<31.00  (7a)
0.90<D2/D3≤2.50  (9′)
30.00<r2/T2  (15)
where
vd6: an abbe number at d-ray of the sixth lens,
D2: a thickness along the optical axis of the second lens,
D3: a thickness along the optical axis of the third lens,
r2: a paraxial curvature radius of an image-side surface of the first lens,
r4: a paraxial curvature radius of an image-side surface of the second lens, and
T2: a distance along an optical axis from an image-side surface of the second lens to an object-side surface of the third lens.