Three-piece lens assembly
AssigneeLargan Precision Co., Ltd.
InventorSayuri Noda
Life of this patent
Estimating the term…
Abstract
A three-piece lens assembly comprises: a first lens group, a second lens group, a third lens group and an aperture. The first lens group is a positive meniscus lens with a convex surface facing the object side and with another surface facing an aperture. The second lens group is a positive meniscus lens with a concave surface facing the aperture and the object side. The third lens group is a biconcave lens with a concave surface facing the second lens and the object side and with another surface facing the image side, and the concave surface of the third lens facing the object side is greater than the another surface of the third lens facing the image side in radius of curvature. Both sides of the first, second and third lens groups are aspheric and are all made of plastic material.
Claims4
A three-piece lens assembly comprising:
- a first lens group being a positive meniscus lens with a convex surface facing the object side and with another surface facing an aperture;
- a second lens group being a positive meniscus lens with a concave surface facing the aperture and the object side;
- a third lens group being a biconcave lens with a concave surface facing the second lens and the object side and with another surface facing the image side, the concave surface of the third lens facing the object side being greater than the another surface of the third lens facing the image side in radius of curvature;
- wherein both sides of the first, second and third lens groups are aspheric and are all made of plastic material;
- a focal length of the first lens group is f1, and a focal length of the second lens group is f2, they satisfy the relation:
- 5.0<f2/f1<18.0.
Dependencies are inferred from the claim text.