US 11,880,022 B2
Lens system, imaging device, and imaging system including a lens element having a free-curve surface
Yoshio Matsumura, Osaka (JP); and Hiroyuki Shobayashi, Hyogo (JP)
Assigned to Panasonic Intellectual Property Management Co., Ltd., Osaka (JP)
Filed by Panasonic Intellectual Property Management Co., Ltd., Osaka (JP)
Filed on Sep. 23, 2020, as Appl. No. 17/029,608.
Application 17/029,608 is a continuation of application No. PCT/JP2018/034867, filed on Sep. 20, 2018.
Claims priority of application No. 2018-062595 (JP), filed on Mar. 28, 2018.
Prior Publication US 2021/0011263 A1, Jan. 14, 2021
Int. Cl. G02B 13/18 (2006.01); G02B 5/00 (2006.01); H04N 23/80 (2023.01); G02B 13/08 (2006.01); G02B 13/00 (2006.01); B60R 1/00 (2022.01); G02B 9/12 (2006.01)
CPC G02B 13/18 (2013.01) [G02B 5/005 (2013.01); G02B 13/0045 (2013.01); G02B 13/08 (2013.01); H04N 23/80 (2023.01); B60R 1/00 (2013.01); B60R 2300/10 (2013.01); B60R 2300/20 (2013.01); G02B 9/12 (2013.01)] 13 Claims
OG exemplary drawing
 
1. A lens system that forms an image on an imaging element, comprising:
a first lens element, a second lens element, and a third lens element, which are arranged in order from an object side to an image surface side along an optical axis; a diaphragm arranged closer to the image surface side than the third lens element; and a lens element on the image surface side, which is arranged closer to the image surface side than the diaphragm,
wherein
at least one of the first lens element and the second lens element has a free-curved surface that is rotational asymmetric with respect to the optical axis, and one of the first lens element and the second lens element has free-curved surfaces on both sides of the object side and the image surface side,
the third lens element has free-curved surfaces that are rotational asymmetric with respect to the optical axis, on both sides of the object side and the image surface side,
the first lens element has a shape of a surface facing the object side, the shape being convex toward the object side,
the second lens element has a shape of a surface facing the image surface side, the shape being convex toward the object side,
the third lens element has a shape of a surface facing the object side, the shape being convex toward the image surface side,
the lens element on the image surface side has, at least on the object side, a free-curved surface that is rotational asymmetric with respect to the optical axis, and
the free-curved surface of at least one of the first lens element and the second lens element satisfies a following conditional expression (1):
0.01<|Smax−Smin|/IH<0.65  (1)
where,
Smax is a maximum sag amount of the free-curved surface at 60% of a longest image height,
Smin is a minimum sag amount of the free-curved surface at 60% of the longest image height, and
IH is a length of 60% of the longest image height.