JPH09236746A - Small sized wideangle lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the small sized wideangle lens thin in total thickness of the lens systm at the time of housing it and excellent in performance by specifying the relationships among refractive powers of each lens lens component. SOLUTION: A first lens component L1 is constituted of a single biconcave lens L(1, 1) having a negative refractive power: ϕ1 . A second lens component L2 is constituted of a positive lens L(2, 1) and a negative lens L(2, 2) and has a positive refractive power: ϕ2 as a whole. A third lens component L3 is conotituted as that a negative lens L(3, 1), a positive lens L(3, 2) and a negative lens L(3, 3) are arranged successively from the object side, and has a positive refractive power: ϕ3 as the lens component. Moreover, a fourthe lens component L4 is constituted of a negative lens L(4, 1) and has a negative refractive power: ϕ4 . Then, refractive powers ϕ1 to ϕ4 satisfy conditional equations 0.7<ϕ1 /ϕ4 <2.5 and 1.8<ϕ2 /ϕ3 <7.0.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a "small wide-angle lens". This wide-angle lens is suitable as a taking lens used in compact cameras and digital cameras.

[0002]

2. Description of the Related Art "Collapse mechanism and storage mechanism" have been adopted for lens shutter cameras, and accordingly, it is required to reduce the "total thickness" of the lens system in the stored state when the camera is not used. ing.

From a practical point of view, such requests are summarized in the following three points. In other words, the F2.8 / 28mm specification "achieves high performance as a shooting lens" and "ensures peripheral light quantity" without increasing the front and rear lens diameters.
That is, "simplify the lens storage mechanism" such as the retractable mechanism without increasing the back focus.

A lens disclosed in Japanese Unexamined Patent Publication No. 5-134175 is known as a lens which responds to such a request. However, when the F2.8 / 28 mm specifications are stored, the ratio of the total lens thickness: D and the focal length: f: D / f is 0.803.
Since it is ˜0.954, the compactness when stored is not always sufficient.

[0005]

In view of the above-mentioned circumstances, the present invention has an object to realize a compact wide-angle lens in which the total thickness of the lens system at the time of storage is thin and the performance is good.

Another object of the present invention is to reduce the performance of a small wide-angle lens with respect to assembly tolerances and improve productivity.

[0007]

As shown in FIG. 1, a small wide-angle lens according to the present invention has a first lens component L1 to a fourth lens component L1 from the object side (left side in the figure) toward the image side. L
4 are arranged, and the second lens component L2 and the third lens component L3 are arranged.
A diaphragm S is provided between and.

In the I-th lens component (I = 1 to 4),
Let the J-th lens counting from the object side be L (I, J).

The first lens component L1 is composed of one biconcave lens L (1,1) and has a negative refracting power: φ ₁ .
The second lens component L2 is composed of one positive lens L (2,1) and one negative lens L (2,2), and has a positive refractive power of φ ₂ as a lens component. As the third lens component L3, one negative lens L (3,1), one positive lens L (3,2), and one negative lens L (3,3) are arranged in this order from the object side. And has a positive refractive power of φ ₃ as a lens component.

The fourth lens component L4 is a negative lens L (4,1).
And has a negative refractive power: φ ₄ .

The above refractive powers: φ _{1 to} φ ₄ satisfy the following conditions: (1) 0.7 <φ ₁ / φ ₄ <2.5 (2) 1.8 <φ ₂ / φ ₃ <7.0 (Claim 1).

The small wide-angle lens described in claim 1 has a lens L (I, J) having a refractive index of N {L (I, J)} and an Abbe number of ν.
{L (I, J)} corresponds to the second lens component L2 and the third lens component L3, and the condition: (3) 1.7 <{N {L (2,1)} + N {L (3,2) )} / 2 (4) 7 <ν {L (2,1)} − ν {L (2,2)} can be satisfied (claim 2). In FIG.
The above N {L (2,1)} and N {L (3,2)} are N ₂ and N ₅ , respectively, and ν {L (2,1)} and ν {L (2,2)} are Ν ₂ , respectively
ν ₃ .

In the I-th lens component LI, the radius of curvature of the K-th refracting surface counted from the object side is R (I, K).

The small wide-angle lens according to claim 2 is
The fourth lens component L4 is a negative single lens, and at least the first surface (the surface on the object side) thereof is an “aspherical surface whose divergent action becomes stronger as it approaches the periphery”, and the fourth lens component L4 is
Condition: (5) −6 <{R (4,1) + R (4,2)} / {R (4,1) −R (4,2)} <2 can be configured (claim 3).

Alternatively, in the small wide-angle lens according to the second aspect, as shown in FIG. 3 for the fourth lens component L4, "a thin resin layer PL is formed on the object side surface, and the surface of the resin layer PL is A hybrid lens having an aspherical shape ". In this case, the fourth lens component L
4 has three surfaces, that is, the surface (aspherical surface) of the resin layer PL, the object side lens surface (spherical surface) and the image side lens surface (spherical surface), and the radius of curvature is R (4 , 1), R (4,
2) and R (4,3). Of course, R (4,1) is the "paraxial radius of curvature".

At this time, the paraxial radius of curvature of the resin layer surface: R
(4,1) and the radius of curvature of the image side lens surface: R (4,3), the condition is (5A) -6 <{R (4,1) + R (4,3)} / {R (4,3) It can be configured to satisfy 1) -R (4,3)} <2 (claim 4).

That is, in the compact wide-angle lens according to the second aspect, the fourth lens component L4 may be a negative single lens and an aspherical surface may be adopted for the lens surface, or the fourth lens component may be a hybrid lens. Alternatively, an aspherical surface may be adopted on the surface of the resin layer.

In the small wide-angle lens according to claim 3 or 4, the negative lenses L (3,1), L (3,2), L (3,3) forming the third lens component L3 are 2, the concave lens L (3,
1), a biconvex lens L (3, 2), and a concave lens L (3, 3), of which the biconvex lens L (3, 2) and the concave lens L
It is possible to make a "junction lens" by bonding (3, 3) together.

In this case, the refractive power of the air lens sandwiched between the concave lens L (3,1) and the biconvex lens L (3,2): φ
The refractive powers of _A and the whole system: φ can be set to satisfy the condition: (6) 0.2 <φ _A /φ<1.8 (claim 5).

Alternatively, in the small-sized wide-angle lens according to the third or fourth aspect, the third lens component L3 includes a "biconcave lens L (3,1) and a biconvex lens L" as illustrated in FIG.
(3, 2) and a concave meniscus lens L (3, 3) are cemented together to form a refracted lens at the cemented surface between the biconcave lens L (3, 1) and the biconvex lens L (3, 2). The power: φ _C and the refractive power of the entire system: φ may satisfy the condition: (7) 0.15 <φ _C /φ<0.5 (claim 6).

In the compact wide-angle lens according to claim 3 or 4, the first lens component L1 has a condition: (8) -1 <{R (1,1) + R (1,2)} / {R ( It is possible to satisfy (1,1) -R (1,2)} <0 (claim 7).

The small wide-angle lens of the present invention has a refractive power:
With the arrangement of φ _{1 to} φ ₄ , it is easy to realize high performance.
It uses a symmetric type of "positive / negative". However, if the lens shape is also symmetrical, it is difficult to reduce the aforementioned "D / f".

Therefore, in the present invention, the power φ ₁
By making φ ₄ satisfy the above conditions (1) and (2) and making the first lens component L1 a “biconcave lens” instead of a negative meniscus lens, the total thickness at the time of storage can be reduced ( Both thinness and high performance have been achieved.

Although making the power of the first lens component L1 negative has the disadvantage of making the overall length of the lens system compact,
In the present invention, the fourth lens component L4 is also allowed to share a strong negative refracting power to partially form a "telephoto system", thereby achieving a reduction in overall length. By making the object side surface of the first lens component L1 concave, it is possible to "move the entrance pupil to the object side" and "ensure peripheral light quantity" without increasing the front lens diameter.

The condition (1) is the first lens component L1 and the fourth lens component L1.
The "power ratio" of the lens component L4 is specified. When the lens configuration as in the present invention is adopted, it is difficult to reduce the thickness of the lens on the object side of the diaphragm S. In this case, the preferable range for the power ratio is determined by the "principle of leverage" regarding the symmetry of the power arrangement and the demand for high performance and thin overall length.

When the value goes below the lower limit of the condition (1), the symmetry of the power arrangement is broken, it becomes difficult to correct the field curvature, and the distortion aberration becomes excessive in the "pincushion shape". If the upper limit is exceeded, the total lens length (distance from the first surface to the image plane) will not be reduced, and the total thickness during storage will be thin, but the amount of movement for storage such as collapsing will be large, and the lens storage The mechanism for is complicated.

The condition (2) is the second lens component L2 and the third lens component L2.
It defines the "power ratio" of the lens component L3. This condition (2) is a condition for achieving both compactness and high performance of the lens system.

When the lower limit of the condition (2) is exceeded, the back focus becomes large, and when the upper limit is exceeded, spherical aberration becomes excessive and correction becomes difficult.

The small wide-angle lens according to the present invention has a seven-lens structure. Among the seven lenses, two convex lenses (L (2,
1) and L (3, 2)), and suppressing the occurrence of aberrations in these two convex lenses leads to higher performance and slower performance deterioration due to assembly errors.

When the lower limit of the condition (3) is exceeded, the Petzval sum becomes large and astigmatism and field curvature become negative, which makes correction difficult. Further, when the second lens component L2 or the third lens component L3 has a cemented lens, if the predetermined power is attempted to be achieved while the lower limit of the condition (3) is exceeded, the curvature of the cemented surface increases, and It is difficult to secure the edge thickness, the polishing is difficult, and the total thickness becomes large.

By correcting chromatic aberrations on the object side and the image side of the stop S, it is possible to achieve both axial and lateral chromatic aberration corrections.

The condition (4) is because of this, the second lens component L
If the lower limit of the condition is not satisfied, the selection of the material for the first lens component L1 may result in insufficient correction of chromatic aberration on the object side of the diaphragm, or the power arrangement may be broken. Further, when the cemented lens is used as the second lens component, the curvature of the cemented surface becomes large, and the edge thickness of the convex lens is secured, so that the effect of making the object side thinner than the diaphragm S decreases.

Since the fourth lens component L4 is farthest from the diaphragm S and is close to the image plane, the light flux passing through the fourth lens component L4 has a narrow width. Therefore, it is easy to control the image plane while suppressing the occurrence of “coma aberration”. Therefore, it is effective to adopt an "aspherical surface" for the fourth lens component, and by making the aspherical surface "aspherical shape in which the divergent action becomes stronger as it approaches the peripheral portion", an image that tends to be underexposed. It becomes possible to correct the surface curvature.

However, if the lower limit of the condition (5) is exceeded, the divergent action of the marginal light flux (upper light ray) of the fourth lens component L4 becomes too strong, and it becomes difficult to correct coma. Moreover, the curvature R (4,1) of the fourth lens component L4 on the object side surface becomes too strong, which makes it difficult to manufacture the lens and makes it difficult to reduce the total thickness.

When the value exceeds the upper limit of the condition (5), it is advantageous for manufacturing and reducing the total thickness, but the refraction angle of the lower ray on the image side surface becomes excessively large, and the diverging action becomes strong, so that the outward direction is increased. It is easy to cause coma and difficult to correct.

The fourth lens component L4 is assembled in the lens unit, and the object side surface thereof is inside the unit so that the user's hand is not directly touched. Although the surface of the resin layer in the hybrid lens is easily damaged, if the resin layer is formed on the object side surface of the fourth lens component L4 as described above, it is possible to effectively prevent damage to the resin layer due to physical force. Since the hybrid lens can be manufactured more easily than forming the aspherical surface directly on the lens surface of the glass lens, it is effective in cost reduction.

As described above, even when the fourth lens component L4 is a hybrid lens, the aspherical surface is formed so that "the diverging action becomes stronger toward the peripheral portion".
The curvature of the surface on which the resin layer is formed: R (4,2) is the curvature of the spherical surface.

When the fourth lens component L4 is a hybrid lens, the same condition (5A) as the above condition (5) is applied for the same reason as when the glass surface of the fourth lens component L4 is directly made aspheric. It is desirable to be satisfied.

In the case of a compact wide-angle lens according to claim 5, when the biconvex lens L (3,2) of the third lens component L3 and the concave lens L (3,3) are cemented together, the concave lens L The "air lens" sandwiched between (3,1) and the biconvex lens L (3,2) can be used for aberration correction and is effective for achieving high performance. In this case, the refraction of the air lens Power:
φ _A plays an important role.

The condition (6) defines the refracting power of the air lens, and when the value goes below the lower limit of the condition (6), the air lens has a role of sharing various aberrations, particularly distortion and astigmatism coefficients. It becomes difficult to balance the entire aberration. If the upper limit is exceeded, the diverging action of the lower ray will be excessive and coma will occur, and the performance will be the third lens component L.
3 is sensitive to the assembling error, and even a slight assembling error significantly deteriorates the performance.

When the third lens component L3 is configured as a cemented lens of three lenses constituting the third lens component as in the small wide-angle lens according to claim 6, the performance of the third lens component L3 itself is improved. It becomes extremely insensitive to manufacturing errors and eccentricity, which is extremely advantageous for parts processing and unit assembly. At this time, the refractive power of the cemented surface between the lens L (3,1) and the lens L (3,2): φ _C plays an important role.

The condition (7) defines the refractive power: φ _C , and if the lower limit is exceeded, the role of the cemented surface in sharing various aberrations, particularly distortion and astigmatism coefficients, decreases, and overall aberrations are reduced. Is difficult to balance. When the value exceeds the upper limit, the curvature of the cemented surface becomes large, which makes it difficult to process the lens L (3, 2).

If a large number of joint surfaces of the lens are used as in the sixth aspect of the invention, the boundary surface between the air and the lens is reduced, which is effective as a ghost countermeasure.

In the present invention, the first lens component L1 is a "biconcave lens", but by breaking the "symmetry" of the diaphragm of the biconcave lens with respect to the final lens, the total thickness of the wide-angle lens can be reduced. It

The condition (8) defines the shape of the first lens component L1 whose symmetry is broken. When the lower limit is exceeded, the curvature of the object side lens surface of the first lens component L1 becomes the curvature of the image side lens surface. Since it is too large in comparison, a large divergence effect occurs on the object-side lens surface, and it becomes difficult to correct spherical aberration and coma with other surfaces. When the value exceeds the upper limit of the condition (8), the refractive power of the first lens component L1 tends to be insufficient, and it becomes difficult to correct the field curvature.

When an aspherical surface is used for the first lens L1, it is preferable to adopt an "aspherical surface having a stronger diverging action toward the periphery" on the object side surface. By adopting such an aspherical surface, it becomes possible to correct the field curvature and the coma that occur on the final surface of the second lens component L2.

In the compact wide-angle lens of the eighth aspect of the present invention, the first to fourth lens components are arranged in order from the object side to the image side, and between the second lens component and the third lens component. The first lens component is composed of a biconcave lens and has a negative refracting power, and the second lens component is
It has a positive refracting power by being composed of one positive lens and one negative lens, and the third lens component is composed of three lenses arranged in order from the object side: the negative lens, the positive lens, and the negative lens. The fourth lens component is composed of a lens and has a negative refractive power, and the fourth lens component is composed of a negative lens and has a negative refractive power.
Refractive index of each lens of the lens component: N {L (3,1)}, N
{L (3,2)}, N {L (3,3)} are conditions: (9) 0.1 <N {L (3,2)}-{[N {L (3,1)} + N It is characterized in that {L (3,3)}] / 2} is satisfied.

In the lens structure as described above, although the third lens component has a "positive refractive power", it is composed of two negative lenses and one positive lens. Therefore, the positive refracting power of the third lens component needs to be realized by setting the refracting power of the positive lens to be strong, so that the aberration of convergence tends to occur excessively.

The condition (9) is that in such a situation,
This is a condition for increasing the refractive index of the material of the positive lens as compared with the refractive index of the material of the negative lens so as to balance the aberration sharing in each lens and achieve high performance. When the value goes below the lower limit of the condition (9), especially the Petzval sum becomes positive and large, the field curvature deteriorates, and it becomes difficult to realize a wide angle.

The condition (9) can, of course, be satisfied also in the small wide-angle lens described in claim 1 or 2 (claim 9) and also in the small wide-angle lens described in claim 3 or 4. The present invention can be performed (claim 10), and can be satisfied even in the small wide-angle lens according to claim 5 or 6 (claim 11).

In particular, in the invention as defined in claim 5 or 6, two or more lenses of the third lens component are cemented together to form a cemented lens, but since the cemented surface is a surface having convergence, the condition (9) is satisfied. ) Is more effective.

Of course, also in the small wide-angle lens according to claim 10, the first lens component can satisfy the condition (8) (claim 12).

[0053]

BEST MODE FOR CARRYING OUT THE INVENTION Seven specific examples will be given below as embodiments of the invention. As shown in FIG. 1, the radius of curvature of the i-th surface (including the surface of the diaphragm S as well as the surface of the refraction surface (including the surface of the resin layer) counted from the object side (close to that of an aspherical surface) The axial curvature radius) is R _i, and the surface distance between the i-th surface and the i + 1-th surface is D _i . Also, the refractive index and the Abbe number of the material of the j-th lens (including the resin layer) counted from the object side are N _j and ν _j , respectively.
And f is the focal length of the entire system, F / No. Is the brightness, ω
Represents a half angle of view.

As is well known, the "aspherical surface" has a paraxial radius of curvature R, a conic constant K, and a higher-order coefficient A when the coordinate is X in the optical axis direction and the coordinate is Y in the direction orthogonal to the optical axis. , B, C,
D,. . . X = (Y ² / R) / [1 + √ {1- (1 + K) (Y / R) ² }] + A
^{· Y 4 + B · Y 6} + C · Y 8 + D · Y 10 becomes R in formula, K, A, B, C , D ,. . Is a surface shape obtained by rotating the specified curved shape around the optical axis. In the above A to D notations, E and the number following it represent “10 to the power”. For example, "E-11"
If so, this means "10 to ¹¹ ", and this number is multiplied by the value immediately before it.

[0055]

【Example】

Example 1 f = 28.1, F / No. = 2.88, ω = 37.2 i R _i D _i j N _j ν _j 1 -24.427 1.00 1 1.64769 33.8 2 48.935 0.08 3 12.031 3.43 2. 1.75700 47.7 4 −14.840 0.90 3 1.68893 31.2 5 −36.502 0.80 6 ∞ (aperture) 2.41 7 −10.144 0.80 4 1.48749 70 .4 8 34.733 4.37 5 1.83500 43.09 -8.514 0.80 6 1.74077 27.8 10 -19.156 2.45 11 -9.270 1.20 7 1. 60342 38.0 12 -16.394.

Aspheric surface First surface K = -0.0665, A = -2.7200E-5, B =
-1.4150E-6, C = 4.4660E-8, D
= -6.1390E-10 Eleventh surface K = 0.5327, A = -8.3178E-5, B =
2.8840E-6, C = -1.0011E-7, D
= 1.0731E-9.

Value of Parameter of Conditional Expression Condition (1): 1.44, Condition (2): 4.17, Condition (3): 1.8, Condition (4): 16.6, Condition (5) :
-3.6, condition (7): 0.281 condition (8): -0.334, condition (9): 0.2208
7.

Example 2 f = 28.8, F / No. = 2.89, ω = 36.5 i R _i D _i j N _j v _j 1 −26.372 0.90 1 1.68682 30.1 2 36.978 0.10 3 12.359 3.392 1.82907 37.7 4 -12.344 0.80 3 1.75273 26.795 -44.069 0.80 6 ∞ (aperture) 2.15 7 -11.067 0.80 4 1.54331 47 .8 8 30.398 4.28 5 1.83400 37.3 9 −7.748 0.80 6 1.74512 27.1 10 −19.873 1.89 11 −9.934 1.00 7 1. 62765 34.7 12-12.185.

Aspheric surface First surface K = 0.6157, A = -1.9810E-5, B =
-1.4141E-6, C = 4.4671E-8, D
= -6.2712E-10 Eleventh surface K = 0.8971, A = -5.86969E-5, B =
3.4204E-6, C = -1.2977E-7, D
= 1.8051E-9.

Value of Parameter of Conditional Expression Condition (1): 1.96, Condition (2): 5.48, Condition (3): 1.83, Condition (4): 10.9, Condition (5) : -4.18, condition (7): 0.38 condition (8): -0.167, condition (9): 0.1897
85.

Example 3 f = 28.8, F / No. = 2.88, ω = 36.5 i R _i D _i j N _j ν _j 1 -22.144 1.01 1 1.56019 44.0 2 71.703 0.10 3 13.622 3.10 2 1.78195 42.4 4 -13.524 1.20 3 1.846666 23.8 5 -39.852 1.06 6 ∞ (aperture) 2.12 7 -11.682 0.80 4 1.48749 70 .4 8 25.478 4.80 5 1.83400 37.3 9 -7.529 0.80 6 1.74616 27.1 10 -21.181 2.51 11 -10.086 1.00 7 1. 65182 32.5 12 -18.682.

Aspherical surface 11th surface K = 0.7178, A = -6.3549E-5, B =
2.4889E-6, C = -8.9139E-8, D
= 1.0759E-9.

Value of Parameter of Conditional Expression Condition (1): 1.17, Condition (2): 3.01, Condition (3): 1.81, Condition (4): 18.6, Condition (5) : -3.35, condition (7): 0.336, condition (8): -0.528, condition (9): 0.217175 The above-mentioned Examples 1 to 3 are Claims 1, 2, 3, 6, and 6. 7, 8,
It is an embodiment of the invention described in 9, 10, 11, and 12, and the lens configuration is the type shown in FIG.

Example 4 f = 28.8, F / No. = 2.89, ω = 36.5 i R _i D _i j N _j ν _j 1 -16.781 0.90 1 1.64019 33.5 2 53.983 0.10 3 13.909 3.182 1.83400 37.3 4 -12.759 0.80 3 1.77121 26.1 5 -42.160 0.80 6 ∞ (aperture) 2.59 7 -10.354 0.80 4 1.56606 42 .98-8-27.026 0.10 9 25.935 3.51 5 1.83400 37.3 10 -7.498 0.80 6 1.71440 28.5 11 -42.443 1.21 12-12 .345 1.00 7 1.54160 48.2 13 146.562.

Aspherical 12th surface K = 3.4096, A = -2.4743E-4, B =
-8.4278E-7, C = -4.4788E-8, D
= 5.6849E-10.

Value of Parameter of Conditional Expression Condition (1): 1.43, Condition (2): 2.38, Condition (3): 1.83, Condition (4): 11.2, Condition (5) : -0.788, condition (6): 1.53, condition (8): -0.524, condition (9): 0.19377
.

Example 5 f = 28.8, F / No. = 2.89, ω = 36.5 i R _i D _i j N _j v _j 1 -15.434 0.90 1 1.63792 33.7 2 78.922 0.10 3 14.807 3.23 2. 1.83400 37.3 4 -12.739 0.80 3 1.82925 24.2 5 -30.821 0.80 6 ∞ (aperture) 2.85 7 -10.122 0.80 4 1.53004 51 .4 8-23.841 0.15 9 27.664 4.04 5 1.83400 37.3 10 -7.435 0.80 6 1.72913 27.8 11 -59.794 1.63 12-15 .652 1.00 7 1.51173 57.8 13 146.562.

Aspheric surface 12th surface K = 3.0486, A = -2.1114E-4, B =
-4.8847E-7, C = -4.1489E-8, D
= 5.6600E-10.

Value of Parameter of Conditional Expression Condition (1): 1.54, Condition (2): 2.81, Condition (3): 1.83, Condition (4): 13.1, Condition (5) : -1.03, condition (6): 1.51, condition (8): -0.673, condition (9): 0.204415 The above Examples 4 and 5 are claims 1, 2, 3, and 5. , 7, 8,
It is an embodiment of the invention described in 9, 10, 11, and 12, and the lens configuration is the type shown in FIG.

Example 6 f = 28.2, F / No. = 2.88, ω = 37.2 i R _i D _i j N _j ν _j 1 -14.593 1.00 1 1.63665 33.8 2 215.917 0.05 3 3 15.427 3.14 2 1.83400 37.3 4-12.377 0.80 3 1.83812 24.0 5-29.227 1.00 6 ∞ (aperture) 2.84 7-9.704 0.90 4 1.559978 44 18-19.329 0.05 9 30.900 4.45 5 1.83400 37.3 10-7.417 0.80 6 1.72008 88.2 11-66.298 2.33 12-12 .454 0.10 7 1.51940 52.1 13 -10.710 0.90 8 1.51680 64.2 14 -66.219.

Aspheric surface 12th surface K = 1.6126, A = -1.7912E-4, B =
-5.1823E-7, C = -3.9278E-8, D
= 5.1059E-10.

Value of Parameter of Conditional Expression Condition (1): 1.71, Condition (2): 2.91, Condition (3): 1.83, Condition (4): 13.3, Condition (5)
A):-1.46, condition (6): 1.58, condition (8):-0.873, condition (9): 0.19407 Example 6 is Claim 1,2,4,5,5. 7,8,9,1
These are examples of the invention described in Nos. 0, 11, and 12, and the lens configuration is the type shown in FIG.

Example 7 f = 28.2, F / No. = 2.87, ω = 37.1 i R _i D _i j N _j ν _j 1 −22.251 1.30 1 1.54814 45.8 2 37.536 0.05 3 11.759 3.392 1.72593 51.1 4 -13.236 0.80 3 1.75054 26.9 5 -29.401 1.00 6 ∞ (aperture) 2.30 7 -9.410 0.90 4 1.48749 70 .4 8 101.510 0.05 9 56.392 3.50 5 1.83400 37.3 10 −7.615 0.80 6 1.79341 25.3 11 −15.887 3.10 12 −9. 329 0.10 7 1.51940 52.1 13 8.968 0.90 8 1.61293 37.0 14 -18.232.

Aspheric surface 1st surface K = 0.8747, A = -3.3198E-5, B =
-6.4326E-7, C = 2.2068E-8, D
= -3.1662E-10 12th surface K = 0.5280, A = -9.3420E-5, B =
1.4922E-6, C = -7.0629E-8, D
= 7.4218E-10.

Value of Parameter of Conditional Expression Condition (1): 1.21, Condition (2): 6.35, Condition (3): 1.78, Condition (4): 25.8, Condition (5
A): -3.1, condition (6): 0.282 condition (8): -0.256, condition (9): 0.1935
5 Example 7 is defined in claims 1, 2, 4, 5, 7, 8, 9, 1
These are examples of the invention described in Nos. 0, 11, and 12, and the lens configuration is the type shown in FIG.

Aberration diagrams for Examples 1 to 7 are sequentially shown in FIGS. In each of the examples, various aberrations are sufficiently corrected. In general, in the field curvature of the wide-angle lens, in most cases, the performance is divided by curving toward the plus side in the periphery, but in each of the above-mentioned examples, the balance is maintained at the minus side even in the most peripheral direction. Therefore, it can be seen that the correction is sufficient.

[0077]

As described above, according to the present invention, it is possible to realize a wide-angle lens having a small size and good performance. As is clear from the above embodiments, this wide-angle lens has extremely good performance, and since the total length of the lens is compact, the mechanism for storing it by collapsing is simple, and the total thickness during storage: D and focus. Distance: ratio to f: D / f is 0.549 to
The total thickness is 0.651, which is extremely small.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a lens configuration of the invention of claims 1, 2, 3, 6, 7, 8 to 12.

FIG. 2 is a diagram for explaining a lens configuration of the invention of claims 1, 2, 3, 5, 7, 8-12.

FIG. 3 is a diagram for explaining a lens configuration of the invention of claims 1, 2, 4, 5, 7, 8 to 12.

FIG. 4 is a diagram showing another example of the lens configuration of the present invention according to claims 1, 2, 4, 5, 7, 8 to 12.

FIG. 5 is an aberration diagram for Example 1.

FIG. 6 is an aberration diagram for Example 2.

FIG. 7 is an aberration diagram for Example 3.

FIG. 8 is an aberration diagram for Example 4.

FIG. 9 is an aberration diagram for Example 5.

FIG. 10 is an aberration diagram for Example 6.

FIG. 11 is an aberration diagram for Example 7.

[Explanation of symbols]

 L1 First lens component L2 Second lens component L3 Third lens component L4 Fourth lens component S Aperture

Claims (12)

[Claims] 1. A first lens component comprising a first lens component and a fourth lens component arranged in order from the object side to the image side, and a diaphragm provided between the second lens component and the third lens component. Is composed of a biconcave lens and has a negative refracting power: φ ₁ , and the second lens component is composed of one positive lens and one negative lens and has a positive refracting power: φ ₂ . The third lens component is composed of three lenses arranged in the order of a negative lens, a positive lens, and a negative lens from the object side, and has a positive refractive power: φ ₃ , and the fourth lens component is It is composed of a negative lens and has a negative refracting power: φ ₄ , and the above refracting powers: φ _{1 to} φ ₄ satisfy the following conditions: (1) 0.7 <φ ₁ / φ ₄ <2.5 (2) 1 A small wide-angle lens characterized by satisfying 0.8 <φ ₂ / φ ₃ <7.0. 2. The small wide-angle lens according to claim 1, wherein the J-th lens counted from the object side in the I-th lens component is L (I, J), and the refractive index of the lens L (I, J) is And Abbe numbers are N {L (I, J)} and ν {L (I, J)}, respectively, for the second and third lens components, the condition: (3) 1.7 <{N { L (2,1)} + N {L (3,2)} / 2 (4) 7 <ν {L (2,1)} − ν {L (2,2)} A small wide-angle lens. 3. The small wide-angle lens according to claim 2, wherein the radius of curvature or paraxial radius of curvature of the K-th refracting surface of the I-th lens component counted from the object side is R (I, K). At this time, the fourth lens component is a negative single lens, and at least the first surface is an aspherical surface that has a strong diverging action as it approaches the periphery, and the condition: (5) −6 <{R (4, A compact wide-angle lens characterized by satisfying 1) + R (4,2)} / {R (4,1) -R (4,2)} <2. 4. The small wide-angle lens according to claim 2, wherein the fourth lens component is a hybrid lens in which a thin resin layer is formed on the object side surface and the surface of the resin layer is aspherical. The paraxial radius of curvature of the resin layer surface: R (4,1) and the radius of curvature of the image side lens surface: R (4,3) are: (5A) -6 <{R (4,1) + R (4 , 3)} / {R (4,1) -R (4,3)} <2, which is a small wide-angle lens. 5. The compact wide-angle lens according to claim 3, wherein the third lens component has a concave lens L (3,1) having a surface having a strong curvature facing the object side and a biconvex lens L (3,1). 2) and a concave lens L (3, 3), and the biconvex lens L (3, 2) and the concave lens L (3, 3) are bonded together to form a cemented lens,
The refractive power of the air lens sandwiched between the concave lens L (3,1) and the biconvex lens L (3,2): φ _A and the refractive power of the entire system: φ are as follows: (6) 0.2 <φ _A A small wide-angle lens characterized by satisfying /φ<1.8. 6. The compact wide-angle lens according to claim 3 or 4, wherein the third lens component is a biconcave lens L (3,1) and a biconvex lens L.
A cemented lens in which (3, 2) and a concave meniscus lens L (3, 3) are cemented together, and a cemented surface of a biconcave lens L (3, 1) and a biconvex lens L (3, 2) A small wide-angle lens characterized in that the refractive power: φ _C and the refractive power of the entire system: φ satisfy the condition: (7) 0.15 <φ _C /φ<0.5. 7. The compact wide-angle lens according to claim 3 or 4, wherein the first lens component has the condition: (8) -1 <{R (1,1) + R (1,2)} / {R ( A small wide-angle lens characterized by satisfying 1,1) -R (1,2)} <0. 8. The first to fourth lens components are arranged in order from the object side to the image side, and an aperture is provided between the second lens component and the third lens component. Is composed of a biconcave lens and has a negative refracting power, the second lens component is composed of one positive lens and one negative lens and has a positive refracting power, and the third lens component is It has a positive refracting power by being composed of three lenses arranged in order from the object side, a negative lens, a positive lens, and a negative lens, and the fourth lens component is composed of a negative lens and has a negative refracting power. And has a refractive index of each lens of the third lens component: N {L (3,1)},
N {L (3,2)} and N {L (3,3)} are conditions: (9) 0.1 <N {L (3,2)}-{[N {L (3,1)} A small wide-angle lens characterized by satisfying + N {L (3,3)}] / 2}. 9. The compact wide-angle lens according to claim 1, wherein the refractive index of each lens of the third lens component is N {L (3,1)},
N {L (3,2)} and N {L (3,3)} are conditions: (9) 0.1 <N {L (3,2)}-{[N {L (3,1)} A small wide-angle lens characterized by satisfying + N {L (3,3)}] / 2}. 10. The compact wide-angle lens according to claim 3 or 4, wherein the refractive index of each lens of the third lens component is N {L (3,1)},
N {L (3,2)} and N {L (3,3)} are conditions: (9) 0.1 <N {L (3,2)}-{[N {L (3,1)} A small wide-angle lens characterized by satisfying + N {L (3,3)}] / 2}. 11. The compact wide-angle lens according to claim 5, wherein the refractive index of each lens of the third lens component is N {L (3,1)},
N {L (3,2)} and N {L (3,3)} are conditions: (9) 0.1 <N {L (3,2)}-{[N {L (3,1)} A small wide-angle lens characterized by satisfying + N {L (3,3)}] / 2}. 12. The compact wide-angle lens according to claim 10, wherein the first lens component has the following condition: (8) -1 <{R (1,1) + R (1,2)} / {R (1, A compact wide-angle lens characterized by satisfying 1) -R (1,2)} <0.