Slim lens assembly
View Patent ↗A slim lens assembly in accordance with the invention in order from an object side to an image side along an optical axis, comprises a first lens, a second lens, a third lens and a fourth lens. The first lens is with positive refractive power, which includes a convex surface facing an image side. The second lens is with positive refractive power, which includes a concave surface facing the image side. The third lens is with positive refractive power, which includes a concave surface facing the object side and a convex surface facing the image side. The fourth lens is with positive refractive power.
1. A slim lens assembly comprising, in order from an object side to an image side along an optical axis:
a first lens with positive refractive power, which includes a convex surface facing the image side;
a second lens with positive refractive power, which includes a concave surface facing the image side;
a third lens with positive refractive power, which includes a concave surface facing the object side and a convex surface facing the image side; and
a fourth lens with positive refractive power, which includes a concave surface facing the image side.
2. The slim lens assembly according to claim 1 further comprising a stop disposed between the third lens and the fourth lens.
3. The slim lens assembly according to claim 2 further comprising an electronic sensor on which an object is imaged, wherein a distance on the optical axis between the stop and the electronic sensor is SL, a distance on the optical axis between the object-side surface of the first lens and the electronic sensor is TTL, and they satisfy the relation: 0.3<SL/TTL<0.8.
4. The slim lens assembly according to claim 2 , wherein a composite focal length of the second lens element, the third element and the fourth element is f 234 , the focal length of the first lens element is f 1 , the focal length of the second lens element is f 2 , the focal length of the third lens element is f 3 , the focal length of the fourth lens element is f 4 , a radius of curvature of the image-side surface of the first lens is R 12 and they satisfy the relations: 0<f 234 /f 4 <1, 0<(f 1 +f 3 )/(f 2 +f 4 )<10, R 12 /f 1 <0.
5. The slim lens assembly according to claim 1 , wherein the first lens comprises a convex surface facing the object side.
6. The slim lens assembly according to claim 5 , wherein the fourth lens comprises a convex surface facing the object side and a concave surface facing the image side.
7. The slim lens assembly according to claim 5 , wherein a composite focal length of the second lens element, the third element and the fourth element is f 234 , the focal length of the first lens element is f 1 , the focal length of the second lens element is f 2 , the focal length of the third lens element is f 3 , the focal length of the fourth lens element is f 4 , a radius of curvature of the image-side surface of the first lens is R 12 and they satisfy the relations: 0<f 234 /f 4 <1, 0<(f 1 +f 3 )/(f 2 +f 4 )<10, R 12 /f 1 <0.
8. The slim lens assembly according to claim 1 , wherein a composite focal length of the second lens element, the third element and the fourth element is f 234 , the focal length of the first lens element is f 1 , the focal length of the second lens element is f 2 , the focal length of the third lens element is f 3 , the focal length of the fourth lens element is f 4 , a radius of curvature of the image-side surface of the first lens is R 12 and they satisfy the relations: 0<f 234 /f 4 <1, 0<(f 1 +f 3 )/(f 2 +f 4 )<10, R 12 /f 1 <0.
9. The slim lens assembly according to claim 1 , wherein the fourth lens comprises a convex surface facing the object side.
10. A slim lens assembly comprising, in order from an object side to an image side along an optical axis:
a first lens with positive refractive power, which includes a convex surface facing the image side;
a second lens with positive refractive power, which includes a convex surface facing the object side and a concave surface facing the image side;
a third lens with positive refractive power, which includes a concave surface facing the object side and a convex surface facing the image side;
a stop; and
a fourth lens with positive refractive power.
11. The slim lens assembly according to claim 10 , wherein the first lens includes a convex surface facing the object side, a composite focal length of the second lens element, the third lens element and the fourth lens element is f 234 , and the following condition is satisfied: f 234 >0.
12. The slim lens assembly according to claim 11 , wherein the fourth lens comprises a convex surface facing the object side and a concave surface facing the image side.
13. The slim lens assembly according to claim 11 further comprising an electronic sensor on which an object is imaged, wherein a distance on the optical axis between the stop and the electronic sensor is SL, a distance on the optical axis between the object-side surface of the first lens and the electronic sensor is TTL, and they satisfy the relation: 0.3<SL/TTL<0.8.
14. The slim lens assembly according to claim 11 , wherein a composite focal length of the second lens element, the third element and the fourth element is f 234 , the focal length of the first lens element is f 1 , the focal length of the second lens element is f 2 , the focal length of the third lens element is f 3 , the focal length of the fourth lens element is f 4 , a radius of curvature of the image-side surface of the first lens is R 12 and they satisfy the relations: 0<f 234 /f 4 <1, 0<(f 1 +f 3 )/(f 2 +f 4 )<10, R 12 /f 1 <0.
15. The slim lens assembly according to claim 10 , wherein the fourth lens comprises a convex surface facing the object side and a concave surface facing the image side.
16. The slim lens assembly according to claim 10 further comprising an electronic sensor on which an object is imaged, wherein a distance on the optical axis between the stop and the electronic sensor is SL, a distance on the optical axis between the object-side surface of the first lens and the electronic sensor is TTL, and they satisfy the relation: 0.3<SL/TTL<0.8.
17. The slim lens assembly according to claim 10 , wherein a composite focal length of the second lens element, the third element and the fourth element is f 234 , the focal length of the first lens element is f 1 , the focal length of the second lens element is f 2 , the focal length of the third lens element is f 3 , the focal length of the fourth lens element is f 4 , a radius of curvature of the image-side surface of the first lens is R 12 and they satisfy the relations: 0<f 234 /f 4 <1, 0<(f 1 +f 3 )/(f 2 +f 4 )<10, R 12 /f 1 <0.
18. A slim lens assembly comprising, in order from an object side to an image side along an optical axis:
a first lens with positive refractive power, which includes a convex surface facing the image side;
a second lens with positive refractive power, which includes a concave surface facing the image side;
a third lens with positive refractive power, which includes a concave surface facing the object side and a convex surface facing the image side;
a stop; and
a fourth lens with positive refractive power.
19. The slim lens assembly according to claim 18 , wherein the fourth lens comprises a convex surface facing the object side and a concave surface facing the image side.
20. The slim lens assembly according to claim 18 , wherein the first lens includes a convex surface facing the object side, a composite focal length of the second lens element, the third lens element and the fourth lens element is f 234 , and the following condition is satisfied: f 234 >0.