US 12,235,412 B2
Small lens system for TOF
Ki Youn Noh, Gyeonggi-do (KR); Soon Cheol Choi, Gyeonggi-do (KR); Sung Nyun Kim, Incheon (KR); and Seong Jun Bae, Gyeonggi-do (KR)
Assigned to SEKONIX CO., LTD., Gyeonggi-do (KR)
Filed by SEKONIX CO., LTD., Gyeonggi-do (KR)
Filed on Oct. 19, 2021, as Appl. No. 17/505,321.
Claims priority of application No. 10-2020-0137367 (KR), filed on Oct. 22, 2020.
Prior Publication US 2022/0128795 A1, Apr. 28, 2022
Int. Cl. G02B 13/18 (2006.01); G02B 9/34 (2006.01); G02B 13/00 (2006.01)
CPC G02B 13/004 (2013.01) [G02B 9/34 (2013.01)] 7 Claims
OG exemplary drawing
 
1. A small lens system for a time of flight (TOF) camera comprising a first lens, a second lens, a third lens, and a fourth lens sequentially arranged from an object along an optical axis, wherein
a center thickness (ct1) of the first lens, a center thickness (ct3) of the second lens, a center thickness (ct5) of the third lens, and a center thickness (ct7) of the fourth lens satisfy ct1+ct3>ct5+ct7, ct1>ct3, ct1>ct5, and ct1>ct7,
a front surface of the first lens is convex toward the object while a sagittal (SAG) amount of the first lens is increased depending on a height thereof,
a refractive power (P2) of the second lens satisfies −0.01 mm−1<P2<0.01 mm−1,
a front curvature (C3) and a rear curvature (C4) of the second lens satisfy |C3|<0.1 mm−1 and |C4|<0.1 mm−1,
a lens thickness (et3) at a predetermined height and the center thickness (ct3) of the second lens thereof satisfy |et3|ct3|<5 μm throughout a range of 0-30% of a height of a rear effective radius thereof and satisfy |et3|ct3|<60 μm at 70% of the height of the rear effective radius thereof, and
an f-number of the lens system is less than 1.4.