US 9,810,880 B2
Imaging optical system, image capturing apparatus and electronic device
Po-Lun Hsu, Taichung (TW); Cheng-Chen Lin, Taichung (TW); and Wei-Yu Chen, Taichung (TW)
Assigned to LARGAN PRECISION CO., LTD., Taichung (TW)
Filed by LARGAN PRECISION CO., LTD., Taichung (TW)
Filed on Nov. 4, 2015, as Appl. No. 14/932,006.
Claims priority of application No. 104132208 A (TW), filed on Sep. 30, 2015.
Prior Publication US 2017/0090156 A1, Mar. 30, 2017
Int. Cl. G02B 13/00 (2006.01); G02B 9/62 (2006.01)
CPC G02B 13/0045 (2013.01) [G02B 9/62 (2013.01)] 31 Claims
OG exemplary drawing
 
1. An imaging optical system comprising, in order from an object side to an image side:
a first lens element with positive refractive power having an object-side surface being convex in a paraxial region thereof;
a second lens element having an object-side surface being convex in a paraxial region thereof;
a third lens element having an image-side surface being concave in a paraxial region thereof;
a fourth lens element having an image-side surface being concave in a paraxial region thereof;
a fifth lens element having positive refractive power; and
a sixth lens element with negative refractive power having an image-side surface being concave in a paraxial region thereof, wherein an object-side surface and the image-side surface of the sixth lens element are aspheric, and the image-side surface of the sixth lens element comprises at least one convex shape in an off-axial region thereof;
wherein the imaging optical system has a total of six lens elements, there is an air gap between every two of the first lens element, the second lens element, the third lens element, the fourth lens element, the fifth lens element and the sixth lens element that are adjacent to each other;
wherein a focal length of the first lens element is f1, a focal length of the third lens element is f3, a focal length of the fourth lens element is f4, a focal length of the fifth lens element is f5, a focal length of the sixth lens element is f6, and both |f3| and |f4| are greater than |f1|, |f5| and |f6|;
wherein an axial distance between the object-side surface of the first lens element and the image-side surface of the sixth lens element is Td, a maximum image height of the imaging optical system is ImgH, an Abbe number of the third lens element is V3, an Abbe number of the fourth lens element is V4, a curvature radius of the image-side surface of the third lens element is R6, a curvature radius of the image-side surface of the fourth lens element is R8, a focal length of the imaging optical system is f, an entrance pupil diameter of the imaging optical system is EPD, and the following conditions are satisfied:
Td/ImgH<1.25;
1.5<V3/V4<4.0;
(|R6|+|R8|)/f<5.0; and
1.25<ImgH/EPD≤1.70.