Imaging optical system, image capturing unit and electronic device

Patent metadata

Field	Value
Publication number	US-11480765-B2
Application number	US-202016733094-A
Country	US
Kind code	B2
Filing date	Jan 2, 2020
Priority date	Nov 1, 2019
Publication date	Oct 25, 2022
Grant date	Oct 25, 2022

Abstract

An imaging optical system includes six lens elements which are, in order from an object side to an image side: a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element and a sixth lens element. Each of the six lens elements has an object-side surface facing toward the object side and an image-side surface facing toward the image side. At least one of the six lens elements is a freeform lens element, and at least one of the object-side surface and the image-side surface of the at least one freeform lens element is a freeform surface.

First claim

What is claimed is:

1. An imaging optical system comprising six lens elements, the six lens elements being, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element and a sixth lens element, and each of the six lens elements having an object-side surface facing toward the object side and an image-side surface facing toward the image side;
wherein the fourth lens element has positive refractive power, at least one of the six lens elements is a freeform lens element, and at least one of the object-side surface and the image-side surface of the at least one freeform lens element is a freeform surface;
wherein an axial distance between the object-side surface of the first lens element and an image surface is TL, a maximum image height of the imaging optical system is ImgH, half of a maximum field of view of the imaging optical system is HFOV, a central thickness of the fifth lens element is CT5, a sum of axial distances between each of all adjacent lens elements of the imaging optical system is ΣAT, a minimum value among distances between an optical axis and an edge of an optically effective area of the at least one freeform surface of the at least one freeform lens element is Ymin, a maximum value among displacements in parallel with the optical axis from an intersection point between the at least one freeform surface and the optical axis to a point at a distance of Ymin from the optical axis on the at least one freeform surface is SAG_MAX, a minimum value among displacements in parallel with the optical axis from the intersection point between the at least one freeform surface and the optical axis to a point at a distance of Ymin from the optical axis on the at least one freeform surface is SAG_MIN, an absolute difference between SAG_MAX and SAG_MIN is |ΔSAGmax|, a focal length of the imaging optical system in a maximum image height direction is f, a composite focal length of the first lens element, the second lens element, the third lens element and the fourth lens element in the maximum image height direction is f1234, and the following conditions are satisfied:
0.80< TL/ImgH< 6.0;
50.0[deg.]< HFOV;
0< CT 5/Σ AT< 1.1;

1.0 [um]<|Δ SAG max|; and

0.53< f/f 1234<2.0.

2. The imaging optical system of claim 1 , wherein the axial distance between the object-side surface of the first lens element and the image surface is TL, the maximum image height of the imaging optical system is ImgH, the central thickness of the fifth lens element is CT5, the sum of axial distances between each of all adjacent lens elements of the imaging optical system is ΣAT, and the following conditions are satisfied:
1.0< TL/ImgH< 4.5; and
0.15< CT 5/Σ AT< 0.75.

3. The imaging optical system of claim 1 , wherein an Abbe number of the fifth lens element is V5, an Abbe number of the sixth lens element is V6, a central thickness of the first lens element is CT1, a central thickness of the third lens element is CT3, and the following conditions are satisfied:
20.0< V 5+ V 6<100.0; and
0.15< CT 1/ CT 3<1.0.

4. The imaging optical system of claim 1 , wherein a sum of central thicknesses of all lens elements of the imaging optical system is ΣCT, the sum of axial distances between each of all adjacent lens elements of the imaging optical system is EAT, and the following condition is satisfied:
1.6<Σ CT/ΣAT< 7.0.

5. The imaging optical system of claim 1 , wherein the focal length of the imaging optical system in the maximum image height direction is f, a composite focal length of the third lens element and the fourth lens element in the maximum image height direction is f34, and the following condition is satisfied:
0.70≤ f/f 34<2.0.

6. The imaging optical system of claim 1 , wherein a focal length of the fourth lens element in the maximum image height direction is f4, a central thickness of the fourth lens element is CT4, and the following condition is satisfied:
0< f 4/ CT 4<250.

7. The imaging optical system of claim 1 , wherein the first lens element has negative refractive power, the second lens element has positive refractive power, the image-side surface of the fourth lens element is convex in a paraxial region thereof, the image-side surface of the fifth lens element is convex in a paraxial region thereof, and the image-side surface of the sixth lens element is concave in a paraxial region thereof.

8. The imaging optical system of claim 1 , wherein the minimum value among distances between the optical axis and the edge of the optically effective area of the at least one freeform surface of the at least one freeform lens element is Ymin, the maximum value among displacements in parallel with the optical axis from the intersection point between the at least one freeform surface and the optical axis to a point at a distance of Ymin from the optical axis on the at least one freeform surface is SAG_MAX, the minimum value among displacements in parallel with the optical axis from the intersection point between the at least one freeform surface and the optical axis to a point at a distance of Ymin from the optical axis on the at least one freeform surface is SAG_MIN, the absolute difference between SAG_MAX and SAG_MIN is |ΔSAGmax|, and the following condition is satisfied:
2.0 [um]<|Δ SAG max|.

9. An imaging optical system comprising six lens elements, the six lens elements being, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element and a sixth lens element, and each of the six lens elements having an object-side surface facing toward the object side and an image-side surface facing toward the image side;
wherein at least one of the six lens elements is a freeform lens element, at least one of the object-side surface and the image-side surface of the at least one freeform lens element is a freeform surface, and each of at least three of the six lens elements has an Abbe number smaller than 50.0;
wherein an axial distance between the object-side surface of the first lens element and an image surface is TL, a maximum image height of the imaging optical system is ImgH, half of a maximum field of view of the imaging optical system is HFOV, a minimum value among distances between an optical axis and an edge of an optically effective area of the at least one freeform surface of the at least one freeform lens element is Ymin, a maximum value among displacements in parallel with the optical axis from an intersection point between the at least one freeform surface and the optical axis to a point at a distance of Ymin from the optical axis on the at least one freeform surface is SAG_MAX, a minimum value among displacements in parallel with the optical axis from the intersection point between the at least one freeform surface and the optical axis to a point at a distance of Ymin from the optical axis on the at least one freeform surface is SAG_MIN, an absolute difference between SAG_MAX and SAG_MIN is |ΔSAGmax|, a curvature radius of the image-side surface of the third lens element in a paraxial region thereof and in a maximum image height direction is R6, a curvature radius of the object-side surface of the fourth lens element in a paraxial region thereof and in the maximum image height direction is R7, and the following conditions are satisfied:
0.80< TL/ImgH< 6.0;
50.0[deg.]< HFOV;
1.0 [um]<|Δ SAG max|; and

−2.0< R 6/ R 7<0.

10. The imaging optical system of claim 9 , wherein the axial distance between the object-side surface of the first lens element and the image surface is TL, the maximum image h

Assignees

• Largan Precision Co Ltd

Inventors

• Lin Yu Jui
• Liao Cheng-Yuan
• Wang Jin Sen
• Kuo Tzu-Chieh

Classifications

• H04N23/55

  Optical parts specially adapted for electronic image sensors; Mounting thereof · CPC title

• G02B27/0012

  Optical design, e.g. procedures, algorithms, optimisation routines · CPC title

• G02B27/0018

  with means for preventing ghost images (anti-reflection coatings G02B1/11) · CPC title

• G02B13/0045 Primary

  having five or more lenses · CPC title

• G02B13/06

  Panoramic objectives; So-called "sky lenses" {including panoramic objectives having reflecting surfaces} · CPC title