US 11,874,433 B2
Imaging lens
Yukio Sekine, Sukagawa (JP)
Assigned to TOKYO VISIONARY OPTICS CO., LTD., Tokyo (JP)
Filed by TOKYO VISIONARY OPTICS CO., LTD., Tokyo (JP)
Filed on Sep. 30, 2020, as Appl. No. 17/038,104.
Application 17/038,104 is a continuation of application No. 16/156,754, filed on Oct. 10, 2018, granted, now 11,150,445.
Claims priority of application No. 2017-196848 (JP), filed on Oct. 10, 2017.
Prior Publication US 2021/0080701 A1, Mar. 18, 2021
Int. Cl. G02B 13/00 (2006.01); G02B 9/64 (2006.01)
CPC G02B 13/0045 (2013.01) [G02B 9/64 (2013.01)] 19 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,
a second lens,
a third lens,
a fourth lens having negative refractive power,
a fifth lens having positive refractive power,
a sixth lens, and
a seventh lens, wherein said fourth lens has a convex surface facing the image side near the optical axis, and the following conditional expressions (2a), (3), (13) and (16) are satisfied:
−7.1<f2/f<−2.5  (2a)
0.3<t2/t3<3.3  (3)
50<νd7<60  (13)
2.5<|f34|/f<12.0  (16)
where
f: a focal length of the overall optical system,
f2: a focal length of the second lens,
f34: a composite focal length of the third lens and the fourth lens,
t2: a distance along the optical axis from an image-side surface of the second lens to an object- side surface of the third 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, and
vd7: an abbe number at d-ray of the seventh lens.