Imaging lens and imaging device provided with the same
View Patent ↗An imaging lens substantially consists of five lenses consisting of, in order from the object side: a first lens having a positive refractive power and having a meniscus shape with a convex surface toward the object side; a second lens having a biconcave shape; a third lens having a positive refractive power and having a meniscus shape with a convex surface toward the image side; a fourth lens having a meniscus shape with a convex surface toward the image side; and a fifth lens having a negative refractive power and having a concave surface toward the object side.
1. An imaging lens substantially consisting of five lenses consisting of, in order from an object side:
a first lens having a positive refractive power and having a meniscus shape with a convex surface toward the object side;
a second lens having a biconcave shape;
a third lens having a positive refractive power and having a meniscus shape with a convex surface toward the image side;
a fourth lens having a meniscus shape with a convex surface toward the image side; and
a fifth lens having a negative refractive power and having a concave surface toward the object side.
2. The imaging lens as claimed in claim 1 , wherein the conditional expression below is further satisfied:
0.8< f/f 1<3 (1),
where f is a focal length of the entire system, and f1 is a focal length of the first lens.
3. The imaging lens as claimed in claim 2 , wherein the conditional expression below is satisfied:
1< f/f 1<2.5 (1-1),
where f is a focal length of the entire system, and f1 is a focal length of the first lens.
4. The imaging lens as claimed in claim 1 , wherein the fifth lens has a biconcave shape.
5. The imaging lens as claimed in claim 1 , wherein the fifth lens has an image-side surface having at least one inflection point.
6. The imaging lens as claimed in claim 1 , wherein the fourth lens has a positive refractive power.
7. The imaging lens as claimed in claim 1 , wherein the conditional expression below is satisfied:
0.5< f ·tan ω/ L 5 r< 20 (2),
where f is a focal length of the entire system, ω is a half angle of view, and L5r is a paraxial radius of curvature of an image-side surface of the fifth lens.
8. The imaging lens as claimed in claim 7 , wherein the conditional expression below is satisfied:
0.7< f ·tan ω/ L 5 r< 10 (2-1),
where f is a focal length of the entire system, ω is a half angle of view, and L5r is a paraxial radius of curvature of the image-side surface of the fifth lens.
9. The imaging lens as claimed in claim 8 , wherein the conditional expression below is satisfied:
1 <f ·tan ω/ L 5 r< 5 (2-2),
where f is a focal length of the entire system, ω is a half angle of view, and L5r is a paraxial radius of curvature of the image-side surface of the fifth lens.
10. The imaging lens as claimed in claim 1 , wherein the conditional expression below is satisfied:
−10< f/f 345<0 (3),
where f is a focal length of the entire system, and f345 is a combined focal length of the third to the fifth lenses.
11. The imaging lens as claimed in claim 10 , wherein the conditional expression below is satisfied:
−5< f/f 345<−0.1 (3-1),
where f is a focal length of the entire system and f345 is a combined focal length of the third to the fifth lenses.
12. The imaging lens as claimed in claim 11 , wherein the conditional expression below is satisfied:
−1< f/f 345<−0.15 (3-2),
where f is a focal length of the entire system, and f345 is a combined focal length of the third to the fifth lenses.
13. The imaging lens as claimed in claim 1 , wherein the conditional expression below is satisfied:
0<( L 3 f−L 3 r )/( L 3 f+L 3 r )<1.2 (4),
where L3f is a paraxial radius of curvature of an object-side surface of the third lens, and L3r is a paraxial radius of curvature of an image-side surface of the third lens.
14. The imaging lens as claimed in claim 13 , wherein the conditional expression below is satisfied:
0<( L 3 f−L 3 r )/( L 3 f+L 3 r )<1.1 (4-1),
where L3f is a paraxial radius of curvature of the object-side surface of the third lens, and L3r is a paraxial radius of curvature of the image-side surface of the third lens.
15. The imaging lens as claimed in claim 14 , wherein the conditional expression below is satisfied:
0.05<( L 3 f−L 3 r )/( L 3 f+L 3 r )<1 (4-2),
where L3f is a paraxial radius of curvature of the object-side surface of the third lens, and L3r is a paraxial radius of curvature of the image-side surface of the third lens.
16. The imaging lens as claimed in claim 1 , wherein the conditional expression below is satisfied:
1< TTL/H< 1.55 (5),
where TTL is a distance from an object-side surface of the first lens to an image plane, where a back focus portion of the distance is an equivalent air distance, and H is a maximum image height.
17. The imaging lens as claimed in claim 16 , wherein the conditional expression below is satisfied:
1.2< TTL/H< 1.5 (5-1),
where TTL is a distance from the object-side surface of the first lens to the image plane, where the back focus portion of the distance is an equivalent air distance, and H is a maximum image height.
18. The imaging lens as claimed in claim 17 , wherein the conditional expression below is satisfied:
1.3< TTL/H< 1.45 (5-2),
where TTL is a distance from the object-side surface of the first lens to the image plane, where the back focus portion of the distance is an equivalent air distance, and H is a maximum image height.
19. The imaging lens as claimed in claim 1 , wherein the conditional expression below is satisfied:
0.2< f/f 34<1.1 (6),
where f is a focal length of the entire system, and f34 is a combined focal length of the third lens and the fourth lens.
20. An imaging device comprising the imaging lens as claimed in claim 1 .