US 11,754,814 B2
Imaging lens
Yukio Sekine, Sukagawa (JP); and Masaya Hashimoto, Sukagawa (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. 17/391,788.
Application 17/391,788 is a continuation of application No. 17/364,263, filed on Jun. 30, 2021.
Application 17/364,263 is a continuation of application No. 16/232,655, filed on Dec. 26, 2018, abandoned.
Claims priority of application No. 2017-249708 (JP), filed on Dec. 26, 2017.
Prior Publication US 2021/0364759 A1, Nov. 25, 2021
Int. Cl. G02B 13/00 (2006.01); G02B 9/60 (2006.01)
CPC G02B 13/0045 (2013.01) [G02B 9/60 (2013.01)] 9 Claims
OG exemplary drawing
 
1. An imaging lens comprising in order from an object side to an image side,
a first lens having positive refractive power and a convex surface facing the object side near the optical axis,
a second lens having negative refractive power near the optical axis,
a third lens having the positive refractive power near the optical axis,
a fourth lens, and
a fifth lens having the negative refractive power and a concave surface facing the image side near the optical axis, wherein the image-side surface of said fifth lens is formed as an aspheric surface having at least one off-axial pole point, and below conditional expressions (1), (2), (3), and 7 are satisfied:
0.15<νd4/νd5<0.55  (1)
0.7<T1/T2<3.0  (2)
1.1|r7|/r8  (3)
2.35<T2/T3<8.10  (7)
where
νd4: abbe number at d-ray of the fourth lens,
νd5: abbe number at d-ray of the fifth lens,
T1: distance along the optical axis from the image-side surface of the first lens to the object-side surface of the second lens,
T2: distance along the optical axis from the image-side surface of the second lens to the object-side surface of the third lens,
r7: paraxial curvature radius of the object-side surface of the fourth lens,
r8: paraxial curvature radius of the image-side surface of the fourth lens, and
T3: distance along the optical axis from the image-side surface of the third lens to the object-side surface of the fourth lens.