US 11,982,874 B2
Imaging lens including six lenses of +−−−−+, +−−+−+ or +−−−+− refractive powers
Kenichi Kamada, Sukagawa (JP); and Masaya Hashimoto, Sukagawa (JP)
Assigned to TOKYO VISIONARY OPTICS Co., Ltd., Toyko (JP)
Filed by TOKYO VISIONARY OPTICS CO., LTD., Tokyo (JP)
Filed on Aug. 2, 2021, as Appl. No. 17/391,748.
Application 17/391,748 is a continuation of application No. 16/843,597, filed on Apr. 8, 2020.
Claims priority of application No. 2019-073279 (JP), filed on Apr. 8, 2019.
Prior Publication US 2021/0356696 A1, Nov. 18, 2021
Int. Cl. G02B 13/00 (2006.01); G02B 9/62 (2006.01); G02B 3/04 (2006.01)
CPC G02B 9/62 (2013.01) [G02B 13/0045 (2013.01); G02B 3/04 (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 positive refractive power having an object-side surface being convex in a paraxial region,
a second lens with negative refractive power in a paraxial region, a third lens with negative refractive power in a paraxial region,
a fourth lens with positive or negative refractive power having an object-side surface being convex in a paraxial region,
a fifth lens with positive or negative refractive power in a paraxial region, and
a sixth lens with positive or negative refractive power having an image-side surface being convex in a paraxial region,
wherein an object-side surface of said fifth lens is concave in the paraxial region, the imaging lens has only six lenses with refractive power, and the following conditional expressions (1), (2) (3) and (10a) are satisfied:
39.00<vd3<73.00  (1)
11.00<vd6<26.00  (2)
−8.00<|r11|l/r12  (3)
−10.50<f3/f<−1.35  (10a)
where
vd3: an abbe number at d-ray of the third lens,
vd6: an abbe number at d-ray of the sixth lens,
r11: a paraxial curvature radius of an object-side surface of the sixth lens,
r12: a paraxial curvature radius of an image-side surface of the sixth lens,
f3: a focal length of the third lens, and
f: a focal length of the overall optical system of the imaging lens.