US 12,392,996 B2
Imaging lens
Shingo Yuza, Sukagawa (JP); and Hisao Fukaya, Tokyo (JP)
Assigned to TOKYO VISIONARY OPTICS Co., Ltd., Tokyo (JP)
Filed by TOKYO VISIONARY OPTICS CO., LTD., Tokyo (JP)
Filed on Aug. 3, 2020, as Appl. No. 16/983,494.
Claims priority of application No. 2019-141898 (JP), filed on Aug. 1, 2019.
Prior Publication US 2021/0191079 A1, Jun. 24, 2021
Int. Cl. G02B 13/00 (2006.01); G02B 9/34 (2006.01); G02B 13/06 (2006.01); G02B 27/00 (2006.01); H04N 23/45 (2023.01); H04N 23/55 (2023.01)
CPC G02B 13/004 (2013.01) [G02B 9/34 (2013.01); G02B 13/06 (2013.01); G02B 27/0025 (2013.01); H04N 23/45 (2023.01); H04N 23/55 (2023.01)] 6 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 in a paraxial region,
a second lens with positive or negative refractive power having an object-side surface being concave in a paraxial region,
a third lens with positive refractive power having a biconvex shape with convex surfaces on the object side and the image side in a paraxial region, and
a fourth lens with positive refractive power having an image-side surface being convex in a paraxial region,
wherein the following conditional expressions (1), (2′), (3), (9′), (13″), and (15′) are satisfied:
1.60<|r4|/T2  (1)
2.87<r5/f<3.36  (2′)
−1.40<f1/f4<−0.01  (3)
17.64<(T3/f)<20.27  (9′)
16.30<=r5/T3<=18.97  (13″)
r8/D4<=−3.25  (15′)
where
r4: a paraxial curvature radius of an image-side surface of the second lens,
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,
r5: a paraxial curvature radius of an object-side surface of the third lens,
f: a focal length of the overall optical system of the imaging lens,
f1: a focal length of the first lens,
f4: a focal length of the fourth lens,
T3: a distance along the optical axis from an image-side surface of the third lens to an object-side surface of the fourth lens,
r8: a paraxial curvature radius of an image-side surface of the fourth lens, and
D4: a thickness along the optical axis of the fourth lens.