Imaging lens, camera module, and imaging apparatus
View Patent ↗Disclosed are an imaging lens having a small size and high imaging performance, a camera module that is provided with the imaging lens and can obtain a high-resolution image signal, and an imaging apparatus. An imaging lens includes a first lens having a positive power, a second lens having a negative power, a third lens that has a positive power and includes a convex image-side surface, and a fourth lens that has a negative power and includes an object-side surface which is concave or flat near an optical axis. The first to fourth lenses are arranged in this order from an object side, and the imaging lens satisfies Conditional expression.
1. An imaging lens comprising:
an aperture diaphragm;
a first lens having a positive power;
a second lens having a negative power;
a third lens that has a positive power and includes a convex image-side surface; and
a fourth lens that has a negative power and includes an object-side surface which is concave or flat near an optical axis,
wherein the first to fourth lenses are arranged in this order from an object side, and
the imaging lens satisfies the following conditional expression:
0.5<(| R 2 |−R 1)/( R 1 +|R 2|)
where R 1 indicates a curvature radius of an object-side surface of the first lens and R 2 indicates a curvature radius of an image-side surface of the first lens,
wherein the first lens has a meniscus shape near an optical axis in which a convex surface faces the object side
wherein the imaging lens satisfies the following conditional expression:
0.6 <|f 4 /f|< 1.0
where f indicates a focal length of the entire lens system and f 4 indicates a focal length of the fourth lens.
2. The imaging lens according to claim 1 ,
wherein the imaging lens satisfies the following conditional expression:
0.5 <|f 2 /f|< 4
where f indicates a focal length of the entire lens system and f 2 indicates a focal length of the second lens.
3. The imaging lens according to claim 1 ,
wherein the imaging lens satisfies the following conditional expression:
0.5 <f 3 /f< 2
where f indicates a focal length of the entire lens system and f 3 indicates a focal length of the third lens.
4. The imaging lens according to claim 1 ,
wherein the imaging lens satisfies the following conditional expression:
20<ν1−ν2
where ν 1 indicates an Abbe number of the first lens with respect to the d-line and ν 2 indicates an Abbe number of the second lens with respect to the d-line.
5. The imaging lens according to claim 1 ,
wherein the second lens has a meniscus shape in which a convex surface faces the object side, and satisfies the following conditional expression:
0.1 <D 4 /f< 0.3
where f indicates a focal length of the entire lens system and D 4 indicates a gap between the second lens and the third lens on the optical axis.
6. The imaging lens according to claim 1 ,
wherein the imaging lens satisfies the following conditional expression:
| R 5 |>|R 6|
where R 5 indicates a curvature radius of an object-side surface of the third lens and R 6 indicates a curvature radius of the image-side surface of the third lens.
7. The imaging lens according to claim 1 ,
wherein each of the first lens, the second lens, the third lens, and the fourth lens has at least one aspheric surface.
8. The imaging lens according to claim 1 ,
wherein each of the first lens, the second lens, the third lens, and the fourth lens is made of a resin material.
9. The imaging lens according to claim 1 ,
wherein the first lens is made of a glass material.
10. A camera module comprising:
the imaging lens according to claim 1 ; and
an imaging device that outputs an image signal corresponding to an optical image formed by the imaging lens.
11. An imaging apparatus comprising the camera module according to claim 10 .
12. An imaging lens comprising:
an aperture diaphragm;
a first lens having a positive power;
a second lens having a negative power;
a third lens that has a positive power and includes a convex image-side surface; and
a fourth lens that has a negative power and includes an object-side surface which is concave or flat near an optical axis,
wherein the first to fourth lenses are arranged in this order from an object side, and
the imaging lens satisfies the following conditional expression:
0.5<(| R 2 |−R 1)/( R 1 +|R 2|)
where R 1 indicates a curvature radius of an object-side surface of the first lens and R 2 indicates a curvature radius of an image-side surface of the first lens; and
said aperture diaphragm is provided between the top of the object-side surface of the first lens and the top of an image-side surface of the first lens on the optical axis.
13. The imaging lens according to claim 12 ,
wherein the aperture diaphragm is provided between a top of the object-side surface of the first lens and an edge of the object-side surface of the first lens in an effective diameter range on an optical axis.
14. An imaging lens comprising:
an aperture diaphragm;
a first lens having a positive power;
a second lens having a negative power;
a third lens that has a positive power and includes a convex image-side surface; and
a fourth lens that has a negative power and includes an object-side surface which is concave or flat near an optical axis,
wherein the first to fourth lenses are arranged in this order from an object side, and
the imaging lens satisfies the following conditional expression:
0.5<(| R 2 |−R 1)/( R 1 +|R 2|)
where R 1 indicates a curvature radius of an object-side surface of the first lens and R 2 indicates a curvature radius of an image-side surface of the first lens and
wherein the imaging lens satisfies the following conditional expression:
1.426 ≦|f 2 /f|< 4
wherein f indicates a focal length of the entire lens system and f 2 indicates a focal length of the second lens.
15. The imaging lens according to claim 14 ,
wherein the imaging lens satisfies the following conditional expression:
0.5 <f 3 /f< 2
where f indicates a focal length of the entire lens system and f 3 indicates a focal length of the third lens.
16. The imaging lens according to claim 14 ,
wherein the imaging lens satisfies the following conditional expression:
20<ν1−ν2
where ν 1 indicates an Abbe number of the first lens with respect to the d-line and ν 2 indicates an Abbe number of the second lens with respect to the d-line.
17. The imaging lens according to claim 14 ,
wherein the first lens has a meniscus shape near an optical axis in which a convex surface faces the object side.
18. The imaging lens according to claim 14 ,
wherein the second lens has a meniscus shape in which a convex surface faces the object side, and satisfies the following conditional expression:
0.1 <D 4 /f< 0.3
where f indicates a focal length of the entire lens system and D 4 indicates a gap between the second lens and the third lens on the optical axis.
19. The imaging lens according to claim 14 ,
wherein the aperture diaphragm is disposed in front of the first lens.
20. An imaging lens comprising:
an aperture diaphragm;
a first lens having a positive power;
a second lens having a negative power;
a third lens that has a positive power and includes a convex image-side surface; and
a fourth lens that has a negative power and includes an object-side surface which is concave or flat near an optical axis,
wherein the first to fourth lenses are arranged in this order from an object side, and
the imaging lens satisfies the following conditional expression:
0.5<(| R 2 |−R 1)/( R 1 +|R 2|)
where R 1 indicates a curvature radius of an object-side surface of the first lens and R 2 indicates a curvature radius of an image-side surface of the first lens
wherein the imaging lens satisfies the following conditional expression:
0.9 <f 3 /f< 1.7
wherein f indicates a focal length of the entire lens system and f 3 indicates a focal length of the third lens.
21. The imaging lens according to claim 20 ,
wherein the imaging lens satisfies the following conditional expression:
0.5 <|f 2 /f|< 4
where f indicates a focal length of the entire lens system and f 2 indicates a focal length of the second lens.
22. The imaging lens according to claim 20 ,
wherein the imaging lens satisfies the following conditional expression:
20<ν1−ν2
where ν 1 indicates an Abbe number of the first lens with respect to the d-line and ν 2 indicates an Abbe number of the second lens with respect to the d-line.
23. The imaging lens according to claim 20 ,
wherein the first lens has a meniscus shape near an optical axis in which a convex surface faces the object side.
24. The imaging lens according to claim 20 ,
wherein the second lens has a meniscus shape in which a convex surface faces the object side, and satisfies the following conditional expression:
0.1 <D 4 /f< 0.3
where f indicates a focal length of the entire lens system and D 4 indicates a gap between the second lens and the third lens on the optical axis.
25. The imaging lens according to claim 20 ,
wherein the aperture diaphragm is disposed in front of the first lens.
26. An imaging lens comprising:
an aperture diaphragm;
a first lens having a positive power;
a second lens having a negative power;
a third lens that has a positive power and includes a convex image-side surface; and
a fourth lens that has a negative power and includes an object-side surface which is concave or flat near an optical axis,
wherein the first to fourth lenses are arranged in this order from an object side, and
the imaging lens satisfies the following conditional expression:
0.5<(| R 2 |−R 1)/( R 1 +|R 2|)
where R 1 indicates a curvature radius of an object-side surface of the first lens and R 2 indicates a curvature radius of an image-side surface of the first lens and
wherein the imaging lens satisfies the following conditional expression:
20<ν1−ν≦31.0
where ν 1 indicates an Abbe number of the first lens with respect to the d-line and ν 2 indicates an Abbe number of the second lens with respect to the d-line.
27. The imaging lens according to claim 26 ,
wherein the imaging lens satisfies the following conditional expression:
0.5 <|f 2 /f|< 4
where f indicates a focal length of the entire lens system and f 2 indicates a focal length of the second lens.
28. The imaging lens according to claim 26 ,
wherein the imaging lens satisfies the following conditional expression:
0.5 <f 3 /f< 2
where f indicates a focal length of the entire lens system and f 3 indicates a focal length of the third lens.
29. The imaging lens according to claim 26 ,
wherein the first lens has a meniscus shape near an optical axis in which a convex surface faces the object side.
30. The imaging lens according to claim 26 ,
wherein the second lens has a meniscus shape in which a convex surface faces the object side, and satisfies the following conditional expression:
0.1 <D 4 /f< 0.3
where f indicates a focal length of the entire lens system and D 4 indicates a gap between the second lens and the third lens on the optical axis.
31. The imaging lens according to claim 26 ,
wherein the aperture diaphragm is disposed in front of the first lens.