US 12,352,933 B2
Lens system, imaging device, and imaging system
Yoshio Matsumura, Osaka (JP); Hiroyuki Shobayashi, Hyogo (JP); Takuya Imaoka, Kanagawa (JP); and Tomoko Iiyama, Osaka (JP)
Assigned to PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO., LTD., Osaka (JP)
Filed by Panasonic Intellectual Property Management Co., Ltd., Osaka (JP)
Filed on Mar. 24, 2022, as Appl. No. 17/703,192.
Application 17/703,192 is a continuation of application No. PCT/JP2020/023599, filed on Jun. 16, 2020.
Claims priority of application No. 2019-179910 (JP), filed on Sep. 30, 2019.
Prior Publication US 2022/0214528 A1, Jul. 7, 2022
Int. Cl. G02B 13/08 (2006.01); G02B 9/64 (2006.01); G02B 13/00 (2006.01); G02B 13/14 (2006.01); G02B 13/18 (2006.01); H04N 5/225 (2006.01); H04N 23/55 (2023.01)
CPC G02B 13/08 (2013.01) [G02B 9/64 (2013.01); G02B 13/0045 (2013.01); G02B 13/14 (2013.01); G02B 13/18 (2013.01); H04N 23/55 (2023.01)] 20 Claims
OG exemplary drawing
 
1. A lens system with a telephoto angle of view, comprising:
a plurality of lens elements including eight or less lens elements arranged from an object side to an image plane side; and
a diaphragm arranged between the plurality of lens elements,
wherein the plurality of lens elements include a plurality of freeform lenses each having a freeform surface that is asymmetrical with respect to a first direction and a second direction which cross with each other,
at least three lens elements in the plurality of lens elements placed on the image plane side of the diaphragm, wherein the at least three lens elements includes at least one freeform lens in the plurality of freeform lenses and
the lens system satisfies a conditional expression (1) given below, based on a sum for freeform surfaces of one or more freeform lenses located on the object side of the diaphragm;

OG Complex Work Unit Math
where
N: a total number of the freeform surfaces of the freeform lenses located on the object side of the diaphragm,
k: a number indicating a freeform surface among the total N freeform surfaces,
SAG1k: a sag amount at a position where a height of a k-th freeform surface in the first direction is 40% of an image height in the first direction,
SAG2k: a sag amount at a position where a height of the k-th freeform surface in the second direction is 40% of the image height in the first direction,
Y2: an image height in the second direction,
Θ1: a full angle of view in the first direction, and
Δndk: a difference resulting from subtracting a refractive index on the object side of the k-th freeform surface from a refractive index on the image plane side of the k-th freeform surface with respect to a d-line.