US 11,454,785 B2Granted

Small lens system including eight lenses of −+−+−++− refractive powers

AssigneeSekonix Co., Ltd.

InventorsKi Youn Noh, Soon Cheol Choi, Seong Jun Bae, Su Jeong Kim

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Abstract

Disclosed is a small lens system including a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens, wherein the first lens has a lens surface convex toward an object, the second lens has a lens surface convex toward the object, the third lens has a lens surface convex toward the object, the fourth lens has a positive refractive power, the fifth lens has a negative refractive power, the sixth lens has a lens surface convex toward an image, the seventh lens has a positive refractive power and is configured such that a lens surface is convex toward the object in the vicinity of an optical axis, and the eighth lens has a negative refractive power and is configured such that an object-side surface and an image-side surface are concave in the vicinity of the optical axis.

Claims25

Dependent claims

A small lens system comprising a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens sequentially arranged from an object, wherein

the first lens is a meniscus lens having a lens surface convex toward the object,
the second lens is a meniscus lens configured such that a lens surface having a positive refractive power is convex toward the object,
the third lens is a meniscus lens configured such that a lens surface having a negative refractive power is convex toward the object,
the fourth lens is a lens having a positive refractive power,
the fifth lens is a lens having a negative refractive power,
the sixth lens is a meniscus lens having a lens surface convex toward an image,
the seventh lens is a meniscus lens having a positive refractive power and configured such that a lens surface of the seventh lens is convex toward the object in a vicinity of an optical axis, and
the eighth lens is a lens having a negative refractive power and configured such that both an object-side surface and an image-side surface of the eighth lens are concave in the vicinity of the optical axis, and wherein
all surfaces of the first to eighth lenses are aspherical surfaces,
each of the seventh lens and the eighth lens has at least one inflection point, and
an absolute value of a refractive power (P1) of the first lens satisfies |P1|<0.01,
wherein the small lens system has at least one of the following features (a), (b), (c) and (d):
(a) a ratio of an effective-diameter outermost distance (et12) between the first lens and the second lens to a center distance (c12) between the first lens and the second lens satisfies 6<et12/ct12<10;
(b) a focal distance (f6) of the sixth lens, a focal distance (f7) of the seventh lens, and a focal distance (F) of the entire small lens system are configured to satisfy 1.0<(F/f6)+(F/f7)<−0.5;
(c) an Abbe number (V5) of the fifth lens, an Abbe number (V6) of the sixth lens, an Abbe number (V7) of the seventh lens, and an Abbe number (V8) of the eighth lens satisfy 40<V5<60, 40<V6<60, 40<V7<60, and 40<V8<60, respectively;
and
(d) the first lens has at least one inflection point.

14 more elements

A small lens system comprising a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens sequentially arranged from an object, wherein

the first lens is a meniscus lens having a lens surface convex toward the object,
the second lens is a meniscus lens configured such that a lens surface having a positive refractive power is convex toward the object,
the third lens is a meniscus lens configured such that a lens surface having a negative refractive power is convex toward the object,
the fourth lens is a lens having a positive refractive power,
the fifth lens is a lens having a negative refractive power,
the sixth lens is a meniscus lens having a lens surface convex toward an image,
the seventh lens is a meniscus lens having a positive refractive power and configured such that a lens surface of the seventh lens is convex toward the object in a vicinity of an optical axis, and
the eighth lens is a lens having a negative refractive power and configured such that both an object-side surface and an image-side surface of the eighth lens are concave in the vicinity of the optical axis, and wherein
all surfaces of the first to eighth lenses are aspherical surfaces,
each of the seventh lens and the eighth lens has at least one inflection point,
an absolute value of a refractive power (P1) of the first lens satisfies |P1|<0.01, and
an angle of incidence (AOI) that an ordinary ray of a field forms with a normal line at a point of the image-side surface of the eighth lens through which the ordinary ray passes satisfies AOI<12°,
wherein the small lens system has at least one of the following features (a), (b), (c) and (d):
(a) a ratio of an effective-diameter outermost distance (et12) between the first lens and the second lens to a center distance (c12) between the first lens and the second lens satisfies 6<et12/ct12<10;
(b) a focal distance (f6) of the sixth lens, a focal distance (f7) of the seventh lens, and a focal distance (F) of the entire small lens system are configured to satisfy 1.0<(F/f6)+(F/f7)<−0.5;
(c) an Abbe number (V5) of the fifth lens, an Abbe number (V6) of the sixth lens, an Abbe number (V7) of the seventh lens, and an Abbe number (V8) of the eighth lens satisfy 40<V5<60, 40<V6<60, 40<V7<60, and 40<V8<60, respectively;
and
(d) the first lens has at least one inflection point.

15 more elements

Dependencies are inferred from the claim text.