Imaging lens, imaging device, portable terminal, and method for manufacturing imaging lens

1. An imaging lens comprising: at least one lens block including a lens substrate that is a plane-parallel plate, and a lens contiguous with at least one of object-side and image-side substrate surfaces of the lens substrate, the lens exerting a positive or negative optical power; and an aperture stop restricting light amount, wherein said lens included in said lens block is formed of a material different from a material out of which said lens substrate is formed; wherein said lens block comprises a first lens block disposed at a most object-side position, the first lens block including, as said lens substrate, a first lens substrate, and as said lens, a lens L[LS 1 o] contiguous with an object-side substrate surface of the first lens substrate, wherein an object-side lens surface of the lens L[LS 1 o] is convex to an object side, wherein said lens block further comprises a second lens block located to an image side of the first lens block, the second lens block including, as said lens substrate, a second lens substrate, and as said lens, a lens L[LS 2 o] contiguous with an object-side substrate surface of the second lens substrate and a lens L[LS 2 m] contiguous with an image-side substrate surface of the second lens substrate, wherein an object-side lens surface of the lens L[LS 2 o] is concave to an object side, and wherein conditional formula (A1) below is fulfilled:

0 ≦DT[LS 1 o−ape]/d[LS 1]≦1  (A1)

where

DT[LS 1 o−ape] represents a distance from the object-side substrate surface of the first lens substrate to an aperture stop surface; and d[LS 1 ] represents a thickness of the first lens substrate along an optical axis; and

Wherein conditional formula (A3) is fulfilled:

1.4< f [all] /Y ′<1.9  (A3)

where

f[all] represents a focal length of the entire imaging lens; and

Y′ represents a maximum image height.

2. The imaging lens according to claim 1 ,

wherein the aperture stop is formed on the object-side substrate surface of the first lens substrate.

3. The imaging lens according to claim 1 ,

wherein the aperture stop is a light-shielding film, and is formed on the object-side or image-side substrate surface of the first lens substrate, and

wherein conditional formula (A2) below is fulfilled:

d[ape]<25  (A2)

where

d[ape] represents a thickness of the aperture stop in an optical axis direction (in the unit of μm).

4. The imaging lens according to claim 3 , wherein conditional formula (A4) is fulfilled:

0.18≦( d[L[LS 1 o]]+DT[LS 1 o −ape])/ r[L[LS 1 o]o]≦ 1.2  (A4)

where

d[L[LS 1 o]] represents a thickness of the lens L[LS 1 o] along the optical axis;

DT[LS 1 o−ape] represents a distance from the object-side substrate surface of the first lens substrate to the aperture stop surface; and

r[L[LS 1 o]o] represents a paraxial radius of curvature of the object-side lens surface of the lens L[LS 1 o].

5. The imaging lens according to claim 4 ,

wherein conditional formula (A5) is fulfilled:

0.03 ≦d[LS 1 ]/TL ≦0.33  (A5)

where

d[LS 1 ] represents the thickness of the first lens substrate along the optical axis; and

TL represents a distance from a most object-side surface in the imaging lens LN to an imaging surface along the optical axis.

6. The imaging lens according to claim 5 ,

wherein the first lens block further includes, as said lens, a lens L[LS 1 m] contiguous with an image-side substrate surface of the first lens substrate, and

wherein conditional formula (A6) is fulfilled:

Cs[L[LS 1 o]o]/Cs[L[LS 1 m]m]≦ 1.3  (A6)

where

Cs[L[LS 1 o]o] represents an effective diameter on an object-side lens surface of the lens L[LS 1 o]; and

Cs[L[LS 1 m]m] represents an effective diameter on an image-side lens surface of the lens L[LS 1 m].

7. The imaging lens according to claim 6 ,

wherein the first lens block further includes, as said lens, a lens L[LS 1 m] contiguous with an image-side substrate surface of the first lens substrate, and

wherein conditional formula (A7) is fulfilled:

−13 ≦HY[L[LS 1 m]m]/HY[L[LS 1 o]o]≦− 0.08  (A7)

where

HY[L[LS 1 m]m] represents a distance between the optical axis and a principal ray with a maximum image height which passes through an image-side lens surface of the lens L[LS 1 m]; and

HY[L[LS 1 o]o] represents a distance between the optical axis and a principal ray with the maximum image height which passes through an object-side lens surface of the lens L[LS 1 o].

8. The imaging lens according to claim 1 ,

wherein the first lens block further includes, as said lens, a lens L[LS 1 m] contiguous with an image-side substrate surface of the first lens substrate, and

wherein an image-side lens surface of the lens L[LS 1 m] is concave to an image side.

9. The imaging lens according to claim 1 ,

wherein conditional formulae (A3) and (A4) are fulfilled:

1.4 <f [all]/ Y′< 1.9  (A3)

0.18≦( d[L[LS 1 o]]+DT[LS 1 o −ape])/ r[L[LS 1 o]o] 1.2  (A4)

where

f[all] represents a focal length of the entire imaging lens;

Y′ represents a maximum image height;

d[L[LS 1 o]] represents a thickness of the lens L[LS 1 o] along the optical axis;

DT[LS 1 o −ape] represents a distance from the object-side substrate surface of the first lens substrate to the aperture stop surface; and

r[L[LS 1 o]o] represents a paraxial radius of curvature of the object-side lens surface of the lens L[LS 1 o].

10. The imaging lens according to claim 1 ,

wherein conditional formula (A5) is fulfilled:

0.03 ≦d[LS 1 ]/TL≦ 0.33  (A5)

where

d[LS 1 ] represents the thickness of the first lens substrate along the optical axis; and

TL represents a distance from a most object-side surface in the imaging lens LN to an imaging surface along the optical axis.

11. The imaging lens according to claim 1 ,

wherein said lens substrate is formed by cementing together two flat-plate-shaped glass pieces, and

wherein the aperture stop is located at a cemented surface between the flat-plate-shaped glass pieces.

12. The imaging lens according to claim 1 ,

wherein the first lens block further includes, as said lens, a lens L[LS 1 m] contiguous with an image-side substrate surface of the first lens substrate, and

wherein conditional formula (A6) is fulfilled:

Cs[L[LS 1 o]o]/Cs[L[LS 1 m]m]≦ 1.3  (A6)

where

Cs[L[LS 1 o]o] represents an effective diameter on an object-side lens surface of the lens L[LS 1 o]; and

Cs[L[LS 1 m]m] represents an effective diameter on an image-side lens surface of the lens L[LS 1 m].

13. The imaging lens according to claim 1 ,

wherein the first lens block further includes, as said lens, a lens L[LS 1 m] contiguous with an image-side substrate surface of the first lens substrate, and

wherein conditional formula (A7) is fulfilled:

−13 ≦HY[L[LS 1 m]m]/HY[L[LS 1 o]o]≦− 0.08  (A7)

where

HY[L[LS 1 m]m] represents a distance between the optical axis and a principal ray with a maximum image height which passes through an image-side lens surface of the lens L[LS 1 m]; and

HY[L[LS 1 o]o] represents a distance between the optical axis and a principal ray with the maximum image height which passes through an object-side lens surface of the lens L[LS 1 o].

14. The imaging lens according to claim 1 ,

wherein said lens block further comprises a second lens block located to an image side of the first lens block, the second lens block including,

as said lens substrate, a second lens substrate, and

as said lens,

a lens L[LS 2 o] contiguous with an object-side substrate surface of the second lens substrate and

a lens L[LS 2 m] contiguous with an image-side substrate surface of the second lens substrate,

wherein an object-side lens surface of the lens L[LS 2 o] is aspherical, being convex at a vertex thereof and concave in a part thereof intersecting a principal ray with a maximum image height, and

wherein the object-side substrate surface of the second lens substrate is contiguous with an image-side lens surface of the lens L[LS 2 o], and the image-side substrate surface of the second lens substrate is contiguous with an object-side lens surface of the lens L[LS 2 m].

15. The imaging lens according to claim 1 ,

wherein said lens block further comprises a second lens block located to an image side of the first lens block and a third lens block located to an image side of the second lens block, the third lens block including,

as said lens substrate, a third lens substrate, and

as said lens,

a lens L[LS 3 o] contiguous with an object-side substrate surface of the third lens substrate and

a lens L[LS 3 m] contiguous with an image-side substrate surface of the third lens substrate

wherein an object-side lens surface of the lens L[LS 3 o] is concave to an object side, and

wherein the object-side substrate surface of the third lens substrate is contiguous with an image-side lens surface of the lens L[LS 3 o], and the image-side substrate surface of the third lens substrate is contiguous with an object-side lens surface of the lens L[LS 3 m].

16. The imaging lens according to claim 1 ,

wherein said lens block further comprises a second lens block located to an image side of the first lens block and a third lens block located to an image side of the second lens block, the third lens block including,

as said lens substrate, a third lens substrate, and

as said lens,

a lens L[LS 3 o] contiguous with an object-side substrate surface of the third lens substrate and

a lens L[LS 3 m] contiguous with an image-side substrate surface of the third lens substrate

wherein at least one of an object-side lens surface of the lens L[LS 3 o] and an image-side lens surface of the lens L[LS 3 m] is aspherical, and

wherein the object-side substrate surface of the third lens substrate is contiguous with an image-side lens surface of the lens L[LS 3 o], and the image-side substrate surface of the third lens substrate is contiguous with an object-side lens surface of the lens L[LS 3 m].

17. The imaging lens according to claim 1 , wherein a lens surface of said lens L[LS 1 o] that makes contact with air is aspherical.

18. The imaging lens according to claim 1 , wherein said lens L[LS 1 o] and said lens substrate have different indices of refraction.

19. The imaging lens according to claim 1 , wherein one of said lenses L[LS 1 o], L[LS 2 o], and L[LS 2 m] is formed of resin.

20. The imaging lens according to claim 19 ,

wherein the resin out of which said lens is formed has inorganic fine particles with a particle diameter of 30 nm or less dispersed therein.

21. The imaging lens according to claim 20 ,

wherein the resin is a hardening resin.

22. The imaging lens according to claim 1 ,

wherein said lens contiguous with the object-side or image-side substrate surface of said lens substrate is bonded directly to the lens substrate.

23. An imaging device comprising:

the imaging lens according to claim 1 ; and

an image sensor sensing light passing through the imaging lens.

24. A portable terminal comprising:

the imaging device according to claim 23 .

25. A method of manufacturing an imaging lens according to claim 1 , comprising the steps of:

arranging a spacer at least at part of a peripheral edge of a plurality of lens blocks and joining a plurality of lens block units together; and

cutting the joined-together lens block units along the spacer,

wherein said lens block units comprise a plurality of lens blocks arranged in an array.

26. An imaging lens comprising: at least one lens block disposed at a most object-side position of said imaging system said at least one lens block including:

a plate-like first lens substrate, and a lens L[LS 1 o], having an optical power, bonded to an object-side surface of the first lens substrate, and an aperture stop restricting light amount, wherein said lens included in said at least one lens block is formed of a material different from a material of said first lens substrate; wherein the following conditional formula (A1) is fulfilled:

0 ≦DT[LS 1 o −ape]/ d[LS 1]≦1  (A1)

where

DT[LS 1 o−ape]

represents a distance from the object-side substrate surface of the first lens substrate to an aperture stop surface; and

d[LS 1 ]

represents a thickness of the first lens substrate along an optical axis; and

Wherein conditional formula (A3) is fulfilled:

1.4 <f [all]/Y′<1.9  (A3)

where

f[all] represents a focal length of the entire imaging lens; and

Y′ represents a maximum image height.