Optical imaging lens assembly, image capturing unit and electronic device

1. An optical imaging lens assembly comprising seven lens elements, the seven 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, a sixth lens element and a seventh lens element; each of the seven lens elements having an object-side surface facing toward the object side and an image-side surface facing toward the image side, wherein the object-side surface of the first lens element is convex in a paraxial region thereof, at least one surface among the object-side surfaces and the image-side surfaces of the seven lens elements has at least one inflection point, and each of at least two of the seven lens elements has an Abbe number smaller than 20.0;

wherein an entrance pupil diameter of the optical imaging lens assembly is EPD, a sum of central thicknesses of the seven lens elements of the optical imaging lens assembly is ΣCT, a central thickness of the first lens element is CT 1 , a curvature radius of the object-side surface of the first lens element is R 1 , a focal length of the optical imaging lens assembly is f, and the following conditions are satisfied:

1.45<EPD/(ΣCT-CT1)<5.0;

0.50 <R 1/CT1<3.50; and

2.20 <f/R 1<5.0.

2. The optical imaging lens assembly of claim 1 , wherein the second lens element has negative refractive power, the object-side surface of the second lens element is convex in a paraxial region thereof, the image-side surface of the second lens element is concave in a paraxial region thereof, and at least one surface of at least one lens element among the seven lens elements has at least three inflection points.

3. The optical imaging lens assembly of claim 1 , wherein the entrance pupil diameter of the optical imaging lens assembly is EPD, the sum of central thicknesses of the seven lens elements of the optical imaging lens assembly is ΣCT, the central thickness of the first lens element is CT 1 , 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 optical imaging lens assembly is ImgH, and the following conditions are satisfied:

1.55<EPD/(ΣCT-CT1)<4.0; and

1.20 <TL /ImgH<2.80.

4. The optical imaging lens assembly of claim 1 , wherein an Abbe number of the seventh lens element is V7, and the following condition is satisfied:

V 7<30.0.

5. The optical imaging lens assembly of claim 1 , wherein an axial distance between the second lens element and the third lens element is T 23 , an axial distance between the third lens element and the fourth lens element is T 34 , and the following condition is satisfied:

0.05 <T 23 /T 34<1.0.

6. The optical imaging lens assembly of claim 1 , wherein the image-side surface of the sixth lens element is concave in a paraxial region thereof, a vertical distance between a critical point on the image-side surface of the sixth lens element and an optical axis is Yc 62 , the central thickness of the first lens element is CT 1 , a central thickness of the sixth lens element is CT 6 , the curvature radius of the object-side surface of the first lens element is R 1 , and the following conditions are satisfied:

0.30 <Yc 62/CT6<7.50; and

0.70 <R 1/CT1<2.80.

7. The optical imaging lens assembly of claim 1 , wherein each of at least three of the seven lens elements has an Abbe number smaller than 30.0.

8. The optical imaging lens assembly of claim 1 , wherein a curvature radius of the object-side surface of the seventh lens element is R 13 , a curvature radius of the image-side surface of the seventh lens element is R 14 , an axial distance between the object-side surface of the first lens element and an image surface is TL, the entrance pupil diameter of the optical imaging lens assembly is EPD, and the following conditions are satisfied:

−1.80<( R 13 −R 14)/( R 13 +R 14)<0.50; and

1.25 <TL /EPD<2.0.

9. The optical imaging lens assembly of claim 1 , wherein the focal length of the optical imaging lens assembly is f, a curvature radius of the image-side surface of the sixth lens element is R 12 , and the following condition is satisfied:

2.50 <f/R 12<6.50.

10. The optical imaging lens assembly of claim 1 , wherein the focal length of the optical imaging lens assembly is f, the entrance pupil diameter of the optical imaging lens assembly is EPD, an axial distance between the image-side surface of the seventh lens element and an image surface is BL, an axial distance between the object-side surface of the first lens element and the image-side surface of the seventh lens element is TD, a maximum image height of the optical imaging lens assembly is ImgH, and the following conditions are satisfied:

1.0 <f /EPD<1.90;

0 <BL/TD <0.35; and

1.90 <f /ImgH<3.50.

11. The optical imaging lens assembly of claim 1 , further comprising an aperture stop, wherein an axial distance between the aperture stop and the image-side surface of the seventh lens element is SD, an axial distance between the object-side surface of the first lens element and the image-side surface of the seventh lens element is TD, the focal length of the optical imaging lens assembly is f, a curvature radius of the image-side surface of the seventh lens element is R 14 , and the following conditions are satisfied:

0.70 <SD/TD <0.90; and

| f/R 14|<0.50.

12. The optical imaging lens assembly of claim 1 , wherein the focal length of the optical imaging lens assembly is f, an axial distance between the object-side surface of the first lens element and an image surface is TL, the entrance pupil diameter of the optical imaging lens assembly is EPD, a maximum image height of the optical imaging lens assembly is ImgH, and the following condition is satisfied:

3.0<( f×TL )/(EPD×ImgH)<5.0.

13. The optical imaging lens assembly of claim 1 , wherein the curvature radius of the object-side surface of the first lens element is R 1 , the focal length of the optical imaging lens assembly is f, the central thickness of the first lens element is CT 1 , and the following condition is satisfied:

0.05<( R 1 ×R 1)/( f ×CT1)<0.85.

14. An image capturing unit, comprising:

the optical imaging lens assembly of claim 1 ; and

an image sensor disposed on an image surface of the optical imaging lens assembly.

15. An electronic device, comprising:

the image capturing unit of claim 14 .

16. An optical imaging lens assembly comprising seven lens elements, the seven 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, a sixth lens element and a seventh lens element; each of the seven 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 surface among the object-side surfaces and the image-side surfaces of the seven lens elements has at least one inflection point, each of at least two of the seven lens elements has an Abbe number smaller than 20.0, and each of at least three of the seven lens elements has an Abbe number smaller than 26.0;

wherein an entrance pupil diameter of the optical imaging lens assembly is EPD, a sum of central thicknesses of the seven lens elements of the optical imaging lens assembly is ΣCT, a central thickness of the first lens element is CT 1 , an axial distance between the object-side surface of the first lens element and an image surface is TL, a focal length of the optical imaging lens assembly is f, and the following conditions are satisfied:

1.45<EPD/(ΣCT-CT1)<5.0; and

0.50 <TL/f <1.80.

17. The optical imaging lens assembly of claim 16 , wherein the second lens element has negative refractive power, at least one surface of at least one lens element among the fifth lens element, the sixth lens element and the seventh lens element has at least one inflection point, half of a maximum field of view of the optical imaging lens assembly is HFOV, and the following condition is satisfied:

0.14<tan(HFOV)<0.53.

18. The optical imaging lens assembly of claim 16 , wherein a minimum value among all maximum effective radii of the object-side surfaces and the image-side surfaces of the seven lens elements is Ymin, and a maximum effective radius of at least one surface among the object-side surface of the third lens element, the image-side surface of the third lens element, the object-side surface of the fourth lens element and the image-side surface of the fourth lens element is equal to Ymin.

19. The optical imaging lens assembly of claim 16 , wherein an Abbe number of the first lens element is V1, an Abbe number of the second lens element is V2, an Abbe number of the third lens element is V3, an Abbe number of the fourth lens element is V4, an Abbe number of the fifth lens element is V5, an Abbe number of the sixth lens element is V6, an Abbe number of the seventh lens element is V7, an Abbe number of the i-th lens element is Vi, and the following condition is satisfied:

50.0 <ΣVi <300.0, wherein i= 1˜7.

20. The optical imaging lens assembly of claim 16 , wherein the axial distance between the object-side surface of the first lens element and the image surface is TL, the entrance pupil diameter of the optical imaging lens assembly is EPD, an axial distance between the fifth lens element and the sixth lens element is T 56 , and the following condition is satisfied:

0.80 <TL /(EPD+ T 56)<1.80.

21. The optical imaging lens assembly of claim 16 , wherein the focal length of the optical imaging lens assembly is f, a curvature radius of the object-side surface of the first lens element is R 1 , and the following condition is satisfied:

2.80 <f/R 1<4.0.

22. The optical imaging lens assembly of claim 16 , wherein an Abbe number of at least one lens element having positive refractive power among the seven lens elements is Vp, and the following condition is satisfied:

Vp< 25.0.

23. The optical imaging lens assembly of claim 16 , wherein the focal length of the optical imaging lens assembly is f, the axial distance between the object-side surface of the first lens element and the image surface is TL, the entrance pupil diameter of the optical imaging lens assembly is EPD, a maximum image height of the optical imaging lens assembly is ImgH, and the following condition is satisfied:

2.0<( f×TL )/(EPD×ImgH)<5.20.

24. The optical imaging lens assembly of claim 16 , wherein the axial distance between the object-side surface of the first lens element and the image surface is TL, the entrance pupil diameter of the optical imaging lens assembly is EPD, the focal length of the optical imaging lens assembly is f, and the following conditions are satisfied:

1.25 <TL /EPD<2.0; and

1.0 <f /EPD<2.20.

25. The optical imaging lens assembly of claim 16 , wherein an axial distance between the second lens element and the third lens element is T 2 , an axial distance between the third lens element and the fourth lens element is T 34 , and the following condition is satisfied:

0.30 <T 23 /T 34<0.80.

26. An optical imaging lens assembly comprising seven lens elements, the seven 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, a sixth lens element and a seventh lens element; each of the seven 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 surface among the object-side surfaces and the image-side surfaces of the seven lens elements has at least one inflection point, each of at least two of the seven lens elements has an Abbe number smaller than 20.0, each of at least four of the seven lens elements has an Abbe number smaller than 40.0, and the first lens element has positive refractive power;

wherein an entrance pupil diameter of the optical imaging lens assembly is EPD, a sum of central thicknesses of the seven lens elements of the optical imaging lens assembly is ΣCT, a central thickness of the first lens element is CT 1 , an axial distance between the object-side surface of the first lens element and an image surface is TL, a focal length of the optical imaging lens assembly is f, half of a maximum field of view of the optical imaging lens assembly is HFOV, and the following conditions are satisfied:

0.50<EPD/(ΣCT-CT1)<8.0;

0.50 <TL/f <1.50;

1.0 <f /EPD<1.90; and

0.14<tan(HFOV)<0.53.

27. The optical imaging lens assembly of claim 26 , wherein the object-side surface of the second lens element is convex in a paraxial region thereof, the image-side surface of the second lens element is concave in a paraxial region thereof, the focal length of the optical imaging lens assembly is f, a focal length of the second lens element is f2, and the following condition is satisfied:

−3.0 <f/f 2<0.35.

28. The optical imaging lens assembly of claim 26 , wherein the central thickness of the first lens element is CT 1 , a central thickness of the seventh lens element is CT 7 , the focal length of the optical imaging lens assembly is f, a focal length of the seventh lens element is f7, a curvature radius of the object-side surface of the first lens element is R 1 , and the following conditions are satisfied:

1.70<CT1/CT7;

1.50 <f/R 1<8.0; and

−2.50 <f/f 7<0.90.

29. The optical imaging lens assembly of claim 26 , wherein the focal length of the optical imaging lens assembly is f, the axial distance between the object-side surface of the first lens element and the image surface is TL, the entrance pupil diameter of the optical imaging lens assembly is EPD, a maximum image height of the optical imaging lens assembly is ImgH, and the following condition is satisfied:

2.0<( f×TL )/(EPD×ImgH)<5.20.

30. The optical imaging lens assembly of claim 26 , wherein an axial distance between the fifth lens element and the sixth lens element is T 56 , a sum of axial distances between every adjacent lens elements of the optical imaging lens assembly is ΣAT, a vertical distance between a critical point on the image-side surface of the sixth lens element and an optical axis is Yc 62 , a central thickness of the sixth lens element is CT 6 , and the following conditions are satisfied:

0.15 <T 56/(Σ AT - T 56)<3.0; and

0.30 <Yc 62/CT6<7.50.

31. The optical imaging lens assembly of claim 26 , wherein each of at least four of the seven lens elements has an Abbe number smaller than 30.0.

32. The optical imaging lens assembly of claim 26 , wherein an axial distance between the fifth lens element and the sixth lens element is maximum among axial distances between every adjacent lens elements of the optical imaging lens assembly, an axial distance between the sixth lens element and the seventh lens element is T 67 , a central thickness of the sixth lens element is CT 6 , and the following condition is satisfied:

0.30 <T 67/CT6<4.0.