CN101031836A - Imaging lens - Google Patents

Abstract

The present invention provides a high-efficiency imaging lens capable of shortening the overall length of a lens system and miniaturizing it without increasing the number of lenses, and capable of excellently correcting aberrations. The imaging lens of the present invention is an imaging lens composed of a lens system comprising at least a first lens, an aperture stop and a second lens. The first lens has a convex surface on the object side lens surface, so that the focal length of the first lens is f1, the focal length of the lens system is f, and the radius of curvature of the object-side lens surface of the first lens is r1, then the lens system satisfies the following conditions: 0.5<f1/f<1.5...(1), 1.0<f /r1<4.0...(2), in addition, the second lens is a biconcave lens, and in any one of the first lens (1) and the second lens (2), at least one of the lens surfaces has an aspheric shape, so that When the refractive index of the first lens (1) is n1, the lens system satisfies the following conditions: 0.6<f1/f<1.0...(3), 1.8<(n1-1)f/r1<2.5...(4).

Description

imaging lens

technical field

The present invention relates to an imaging lens mounted on a camera such as a digital still camera (DSC: digital still camera).

Background technique

In recent years, the penetration rate of digital cameras and video cameras using solid-state image sensors such as CCDs is increasing. Furthermore, since the number of portable communication devices such as mobile phones and notebook computers equipped with the solid-state imaging sensors and imaging lenses is also increasing, the demand for imaging lenses used therein is increasing rapidly. Along with the miniaturization, thinning and high efficiency of portable communication equipment, the imaging lens mounted on it is also required to be small, thin and efficient. At the same time, low cost is also required for popularization.

In the prior art, two lenses are used to meet this requirement. Such prior art is disclosed in, for example, JP-A-2001-174701 and JP-A-2002-296495.

In addition, with the rapid popularization of portable communication devices such as mobile phones and notebook computers with camera functions, and PDAs, higher optical performance is required. Therefore, various lenses have been developed as imaging lenses. Such lenses are disclosed in, for example, Japanese Patent Laid-Open No. 2002-258155 and Japanese Patent Laid-Open No. 2004-177628.

Contents of the invention

The imaging lens of the present invention is an imaging lens composed of a lens system including at least a first lens, an aperture stop (aperture stop) and a second lens, wherein,

The first lens is a positive meniscus lens having a convex surface on the object side lens surface,

Let the focal length of the first lens be f1, the focal length of the lens system be f, and the radius of curvature of the object-side lens surface of the first lens be r1, then the lens system satisfies the following conditions:

0.5<f1/f<1.5 ... (1),

1.0<f/r1<4.0 ... (2).

The imaging lens of the present invention is an imaging lens composed of a lens system having at least an aperture stop, a first lens, and a second lens in order from the object side, wherein,

The first lens is a positive meniscus lens having a convex surface on the object side lens surface,

The second lens is a biconcave lens,

In any one of the first lens and the second lens, at least one of the lens surfaces has an aspherical shape,

Let the focal length of the lens system be f, the focal length of the first lens be f1, the refractive index of the first lens (refractive index) be n1, and the radius of curvature of the object side of the first lens be r1, then the lens system satisfies the following two conditional expressions :

0.6<f1/f<1.0 ... (3),

1.8<(n1-1)f/r1<2.5 ... (4).

Description of drawings

FIG. 1 shows a cross-sectional view of an imaging lens in Embodiment 1 of the present invention.

2A to 2C show aberration diagrams for the imaging lens shown in FIG. 1 .

FIG. 3 is a cross-sectional view of an imaging lens in Embodiment 2 of the present invention.

4A to 4C show aberration diagrams of the imaging lens shown in FIG. 3 .

FIG. 5 is a cross-sectional view of an imaging lens in Embodiment 3 of the present invention.

6A to 6C show aberration diagrams about the imaging lens shown in FIG. 5 .

FIG. 7 is a cross-sectional view of an imaging lens in Embodiment 4 of the present invention.

8A to 8C show aberration diagrams for the imaging lens shown in FIG. 7 .

Detailed ways

First, preferred embodiments 1 and 2 of the present invention will be described.

There are the following problems in the imaging lens of the related art. That is, the imaging lenses disclosed in the Japanese Patent Application Laid-Open No. 2001-174701 and the Japanese Patent Laid-Open No. 2002-296495 are all two structural forms, and the lenses constituting the first lens become negative power (also referred to as negative refractive power, negative focal length, or just negative lens) or weaker positive power (also known as positive refractive power, positive focal length, or just positive lens). Therefore, the ratio of the total length of the lens to the focal length of the lens system is large. In the imaging lens disclosed in Japanese Patent Application Laid-Open No. 2001-174701, the ratio of the total length of the lens to the focal length of the lens system is about 2.3 times. In the imaging lens disclosed in KOKAI Publication No. 2002-296495, the ratio of the total lens length to the focal length of the lens system is approximately 1.6 times. Therefore, there is a problem of lack of miniaturization of the structure, especially as an imaging lens used in a mobile phone or the like which has a demand for thinning.

The present invention has been made in view of the problems of the prior art described above, and an object of the present invention is to provide an imaging lens having a high performance while shortening the overall length of the lens system.

The imaging lens of the present invention is an imaging lens composed of a lens system including at least a first lens, an aperture stop and a second lens. The first lens is a positive meniscus lens with a convex surface on the object side lens surface. And, if the focal length of the first lens is f1, the focal length of the lens system is f, and the radius of curvature of the object-side lens surface of the first lens is r1, then the lens system satisfies the following conditions:

0.5<f1/f<1.5 ... (1),

1.0<f/r1<4.0 ... (2).

The imaging lens related to the above structure is composed of two lenses, namely: the first lens as a positive (with power, refractive power or focal length) meniscus lens having a convex surface on the object side lens surface, and the first lens as a positive (with power, refractive power or focal length) meniscus lens on the image side lens surface. A second lens with a convex positive meniscus lens forms a lens system. In addition, an aperture stop is provided on the front (object side) or rear (image side) of the first lens.

Here, the conditional expression (1) in the present invention is a conditional expression that specifies the power (power) arrangement of the front group (front lens) (first lens) of the lens system, and shows that it is possible to achieve a good Conditions for correcting each aberration.

That is, when the ratio of the focal length f1 of the first lens to the focal length f of the lens system exceeds the upper limit of the conditional expression (1), the power allocation for the front group (front lens) of the lens system becomes weak, and the total length of the lens system becomes long. On the contrary, when the lower limit of the conditional expression (1) is exceeded, since the power configuration for the front group (front lens) of the lens system is strengthened, the aberrations generated in the front lens cannot be eliminated by the rear group (rear lens) (second lens) for correction.

In addition, the conditional expression (2) in the present invention is a conditional expression for specifying the power distribution of the object-side lens surface of the first lens of the lens system, and shows that it is possible to have good processability while having a high lens performance. condition.

That is, when the ratio of the radius of curvature r1 of the object side lens surface of the first lens to the focal length f of the lens system exceeds the upper limit of conditional formula (2), the curvature of the first lens object side lens surface is too large, and the first lens Processing becomes difficult. On the other hand, when the lower limit of conditional expression (2) is exceeded, correction of distortion aberration becomes difficult, and at the same time, since the image incident angle in the maximum viewing angle becomes large, especially in an imaging lens using a solid-state imaging element Shading (dark limbs, etc.) occurs, thus not improving the performance of the lens.

Thus, the results of repeated studies by the inventors of the present invention show that by constituting the lens system by two lenses, and each parameter of the lens system meets the conditional formula (1), miniaturization can be realized, and by satisfying the conditional formula (1) (2 ) and various aberrations can be well corrected, and by satisfying the conditional expression (2), an imaging lens with good processability can be developed. By adopting such a lens system, various aberrations can be well corrected while achieving miniaturization.

In this way, according to the imaging lens of the present invention, miniaturization is realized by constituting the lens system with two lenses and each parameter of the lens system satisfies conditional expression (1), and each image can be imaged by satisfying conditional expression (1) (2). The difference is well corrected, and the processability can be improved by satisfying the conditional expression (2).

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

Embodiment 1

FIG. 1 is a cross-sectional view of an imaging lens according to Embodiment 1 of the present invention.

The imaging lens of the present embodiment is constituted by a lens system including a first lens 101 , an aperture stop 103 , and a second lens 102 sequentially from the object side, as shown in FIG. 1 . The first lens 101 is a positive meniscus lens having a convex surface on an object-side lens surface (first lens first surface) 106 . The second lens 102 is a positive meniscus lens having a convex surface on the image side lens surface (second lens second surface) 109 . In addition, an optical member (faceplate or filter) 104 such as a faceplate or a filter in a solid-state imaging device such as a CCD is arranged between the image-side lens surface 109 of the second lens 102 and the imaging surface 105 .

Table 1 shows the parameter values of the imaging lens in the present embodiment having the above-mentioned structure. Here, rj is the radius of curvature (mm) from the object side to the j-th surface number Rj in order. Regarding the surface number Rj, when j is 1, it is the object side lens surface 106 of the first lens 101, when j is 2, it is the image side lens surface (first lens second surface) 107 of the first lens 101, when j is When j is 4, it is the object-side lens surface (second lens first surface) 108 of the second lens 102 , and when j is 4, it is the image-side lens surface 109 of the second lens 101 . dj is the plane center distance (mm) from the object side to the jth in order. Nd is the refractive index of each lens in the d-line (light with a wavelength of 0.58756 μm), νd is the Abbe number of each lens in the d-line, f is the focal length (mm) of the lens system, and Fno. is the full aperture F value (Full Aperture F Value), L represents the total length of the lens system (mm). Among them, * next to the surface number indicates an aspheric surface.

In addition, let the distance (sag) in the optical axis direction of the tangent plane from the vertex of the surface be x, the height from the optical axis be h, the paraxial curvature radius be r, the conic constant be κ, and the mth aspheric surface The coefficient is A _m (m=4, 6, 8, 10, 12), then the aspherical shape can be expressed by the following formula:

x＝{(1/r)h ² }/[1+{1-(1+κ)(1/r) ² h ² } ^1/2 ]+A ₄ h ⁴ +A ₆ h ⁶ +A ₈ h ⁸ +A ₁₀ h ¹⁰ +A ₁₂ h ¹² ... (X).

Therefore, the values of κ and A _m in the above formula (X) are shown below to specify the shape of the aspheric surface.

【Table 1】

f=2.628, Fno=3.2, L=3.305

lens data Face number r j dj Nd νd R1 ^* 0.700 0.5 1.68985 52.83 R2 ^* 0.695 0.12 Aperture stop ∞ 0.475 R3 ^* -2.797 0.908 1.52997 55.73 R4 ^* -1.155 0.15 R5 ∞ 0.5 1.51680 64.20 R6 ∞ 0.652 IMA ∞

Aspheric coefficient R1 R2 R3 R4 kappa 2.8317E-01 2.2685E+00 1.5921E+01 3.7023E-01 A ₄ -4.9731E-02 -1.1404E-01 -4.1096E-01 3.3537E-02 A ₆ 1.5962E-01 -9.7563E-01 2.4183E+00 -3.3923E-01 A ₈ -6.8503E-01 -1.0840E+01 -8.0945E+00 6.2224E-01 A ₁₀ 0.0000E+00 0.0000E+00 9.9482E+00 -4.3038E-01 A ₁₂ 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E+00

In addition, in this embodiment, the focal length f1 of the first lens 101 is 3.542 mm, and the focal length f of the lens system is 2.628 mm. Therefore, 0.5<f1/f=1.34<1.5, satisfying the conditional expression (1). In addition, the curvature radius r1 of the object-side lens surface 106 of the first lens 101 is 0.700 mm. Therefore, 1.0<f/r1=3.75<4.0, satisfying conditional expression (2). In addition, the value L/f normalized by the focal length f of the lens system by the full length L of the lens system was 1.26. Therefore, the total length L of the lens system is not more than 1.3 times the focal length f, and a very compact imaging lens can be realized.

2A to 2C show aberration diagrams for the imaging lens shown in FIG. 1 . Figure 2A shows spherical aberration (spherical aberration), Figure 2B shows astigmatism (ast-igmatism), and Figure 2C shows distortion aberration.

In this embodiment, it is possible not only to realize a very compact imaging lens but also to perform excellent correction of various aberrations as compared with the prior art.

In addition, in the lens system of this embodiment, the lens surfaces 106 , 107 , 108 , and 109 are aspheric lenses, but the present invention is not limited thereto, and can be selected appropriately.

In addition, it is preferable to use a resin material for the first lens and the second lens of the present invention. By using resin material for all the lenses, the manufacturing cost can be reduced and the manufacturing is facilitated.

Embodiment 2

Hereinafter, Embodiment 2 related to the imaging lens of the present invention will be described.

FIG. 3 is a cross-sectional view of an imaging lens in Embodiment 2 of the present invention.

The difference between the imaging lens of this embodiment and Embodiment 1 is that, as shown in FIG. The shape of the side lens surface 109 is different, and the position of the imaging surface 105 is located on the end surface of the optical component (panel and filter) 104 .

Table 2 shows the parameter values of the imaging lens in the present embodiment having the above-mentioned structure. Here, the meanings of the respective numerical values are the same as those in the first embodiment.

【Table 2】

f=2.323, Fno=2.85, L=2.632

lens data Face number r j dj Nd νd Aperture stop ∞ 0.05 R1 ^* 0.782 0.572 1.606019 57.427987 R2 ^* 1.314 0.52 R3 ^* 13.894 0.9 1.478 56 R4 ^* 3.442 0.24 R5 ∞ 0.4 1.516798 64.198258 R6(IMA) ∞

Aspheric coefficient R1 R2 R3 R4 kappa -8.2257E-01 5.1816E-01 0.0000E+00 0.0000E+00 A ₄ 1.8399E-01 4.1192E-01 -6.2582E-01 -4.6135E-01 A ₆ 2.3617E+00 4.4581E+00 1.6949E-01 5.9372E-01 A ₈ -2.2671E+01 -4.7764E+01 1.9894E+00 -7.9928E-01 A ₁₀ 1.2446E+02 2.7136E+02 -1.3495E+01 3.9079E-01 A ₁₂ -2.4472E+02 -4.2054E+02 1.7067E+01 -6.0955E-02

Wherein, in this embodiment, the focal length f1 of the first lens 101 is 2.669 mm, and the focal length f of the lens system is 2.323 mm. Therefore, 0.5<f1/f=0.86<1.5, satisfying the conditional expression (1). In addition, the curvature radius r1 of the object-side lens surface 106 of the first lens 101 is 0.782 mm. Therefore, 1.0<f/r1=2.97<4.0, satisfying conditional expression (2). In addition, the value L/f normalized by the focal length f of the lens system by the full length L of the lens system was 1.13. Therefore, the total length L of the lens system is not more than 1.3 times the focal length f, and a very compact imaging lens can be realized.

4A to 4C show aberration diagrams of the imaging lens shown in FIG. 3 . FIG. 4A shows spherical aberration, FIG. 4B shows astigmatism, and FIG. 4C shows distortion aberration.

In this embodiment, it is possible not only to realize a very compact imaging lens but also to perform excellent correction of various aberrations as compared with the prior art.

In addition, in the lens system of this embodiment, the lens surfaces 106, 107, 108, and 109 are aspherical lenses, but the present invention is not limited thereto, and can be selected appropriately.

Hereinafter, Embodiment 3 and Embodiment 4 of the present invention will be described.

Recently, especially with the miniaturization of the portable communication devices, the imaging lens has a higher optical performance and more miniaturization and lower cost requirements are becoming more and more intense. Therefore, people expect the appearance of an imaging lens with high optical performance exceeding the prior art while reducing the number of lenses, realizing miniaturization and simplifying the structure. In addition, the cost of glass is more than twice the cost of plastic, and when processing glass lenses, the smaller the caliber, the more difficult it is.

The present invention has been made in view of the problems of the prior art described above, and an object of the present invention is to provide an imaging lens capable of miniaturization and excellent correction of aberrations without increasing the number of lenses.

The imaging lens according to the present invention is an imaging lens composed of a lens system including an aperture stop, a first lens, and a second lens in this order from the object side. The first lens is a meniscus lens that is convex on the object side and has positive refractive power. The second lens is a biconcave lens. In any one of the first lens and the second lens, at least one of the lens surfaces has an aspheric shape, and the lens system satisfies the following conditions:

0.6<f1/f<1.0 ... (3),

1.8<(n1-1)f/r1<2.5 ... (4).

Wherein, f is the focal length of the lens system, f1 is the focal length of the first lens, n1 is the refractive index of the first lens, and r1 is the radius of curvature of the object-side surface of the first lens.

Here, the conditional expression (3) in the present invention is a conditional expression that defines the focal length of the first lens, and represents a condition for attaining miniaturization and excellent aberration performance.

That is, when the ratio of the focal length of the first lens to the focal length of the lens system is equal to or less than the lower limit value of conditional expression (3), it is difficult to correct aberrations such as distortion. On the other hand, when the value exceeds the upper limit of the conditional expression (3), the overall size of the device tends to increase, making it impossible to realize a miniaturized lens.

In addition, the conditional expression (4) in the present invention is a conditional expression that specifies the refractive power of the first lens, and represents a condition for achieving miniaturization and excellent aberration performance.

That is, when the predetermined value (n1-1)f/r1 concerning the curvature radius r1 of the object side surface of the first lens, the refractive index n1 of the first lens, and the focal length f of the lens system is equal to or less than the lower limit value of the conditional expression (4) , the axial core thickness of the first lens increases at the center, and a miniaturized lens cannot be realized. On the other hand, when the value is equal to or greater than the upper limit of conditional expression (4), it is difficult to sufficiently pass the off-axis light beam through the first lens, and it is also difficult to correct spherical aberration.

According to the imaging lens of the present invention, by satisfying the conditional expression (3) and the conditional expression (4) of the so-called two-group lens system with a very simple structure, it is possible to obtain a very short overall length, which is about 1.2 times or less of the focal length and has Imaging lens with good aberration performance.

In addition, it is preferable to use a resin material for both the first lens and the second lens of the present invention. By using resin material for all the lenses, the manufacturing cost can be reduced and the manufacturing is facilitated.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

(Embodiment 3)

FIG. 5 is a cross-sectional view of an imaging lens according to Embodiment 3 of the present invention.

As shown in FIG. 5 , the imaging lens of this embodiment is constituted by a lens system including an aperture stop 503 , a first lens 501 , and a second lens 502 in order from the object side. The first lens 501 is a meniscus lens that is convex on the object side lens surface (first lens first surface) 506 and has positive refractive power. The second lens 502 is a biconcave lens. In this embodiment, resin materials are used for both the first lens 501 and the second lens 502 , and any one of the lens surfaces 506 , 507 , 508 , and 509 has an aspherical shape.

Table 3 shows the parameter values of the imaging lens of the present embodiment having the above structure.

Here, rj is the radius of curvature (mm) related to the j-th surface number Rj sequentially from the object side. The surface number R1 is the object-side lens surface 506 of the first lens 501, R2 is the image-side lens surface (first lens second surface) 507 of the first lens 501, and R3 is the object-side lens surface (second lens surface) of the second lens 502. Lens first surface) 508 , R4 is the image-side lens surface (second lens second surface) 509 of the second lens 501 . dj is the center-to-center distance (mm) from the object side to the j-th surface in order. Nd is the refractive index of the lens related to the d-line, νd is the Abbe number of each lens on the d-line, f is the focal length (mm) of the lens system, and Fno. is the full-aperture F value.

In addition, let the distance (sag) in the optical axis direction of the tangent plane from the vertex of the surface be x, the height from the optical axis be h, the paraxial curvature radius be r, the conic constant be κ, and the mth aspheric surface The coefficient is A _m (m=4, 6, 8, 10, 12), then the aspheric shape can be expressed by the following formula:

x＝{(1/r)h ² }/[1+{1-(1+κ)(1/r) ² h ² } ^1/2 ]+A ₄ h ⁴ +A ₆ h ⁶ +A ₈ h ⁸ +A ₁₀ h ¹⁰ +A ₁₂ h ¹² ... (X).

Therefore, the values of κ and A _m in the above formula (X) are shown below to specify the shape of the aspheric surface.

【table 3】

f=4.64, Fno=4.02

lens data Face number r j dj Nd νd Aperture stop ∞ 0.00 R1 1.332 0.84 1.5247 56.40 R2 2.608 1.06 R3 -51.691 2.00 1.5247 56.40 R4 7.318 1.06 IMA ∞

Aspheric coefficient R1 R2 R3 R4 kappa -1.7046E+00 -6.2653E+01 0.0000E+00 -2.5790E+00 A ₄ 8.3075E-02 4.3744E-01 -8.6810E-02 -1.8699E-02 A ₆ 1.3124E-01 -7.0522E-01 -1.2928E-02 -5.8500E-03 A ₈ -1.8008E-01 1.0322E+00 5.3340E-03 1.2880E-03 A ₁₀ 9.4460E-04 -4.4363E-02 5.7170E-02 -1.3600E-05 A ₁₂ 0.0000E+00 0.0000E+00 0.0000E+00 0.0000E-00

In addition, in this embodiment, the focal length f1 of the first lens 501 is 4.21 mm, and the focal length f of the lens system is 4.64 mm. Therefore, 0.6<f1/f=0.91<1.0, satisfying the conditional expression (3). In addition, the refractive index n1 of the first lens 501 is 1.5247, and the curvature radius r1 of the object side surface 506 of the first lens 501 is 1.332 mm. Therefore, 1.8<(n1-1)f/r1=1.83<2.5, satisfying conditional expression (4).

6A to 6C show aberration diagrams of the imaging lens shown in FIG. 5 . FIG. 6A shows spherical aberration, FIG. 6B shows astigmatism, and FIG. 6C shows distortion aberration.

As shown in FIG. 6 , since conditional expressions (21) and conditional expressions (22) are satisfied by making two groups of lens systems with a very simple structure, it is possible to obtain a very short lens system that is less than 1.2 times the focal length and has a good Imaging lenses with aberration performance. In addition, since all the lenses are made of resin material, the manufacturing cost can be reduced and the manufacturing is facilitated.

(fourth embodiment)

FIG. 7 is a cross-sectional view of an imaging lens according to Embodiment 4 of the present invention.

This fourth embodiment is configured using the same lens system as that of the third embodiment. The parameter values (including aspheric coefficients) of the imaging lens in this embodiment are shown in (Table 4).

Wherein, in this embodiment, the focal length f1 of the first lens 501 is 3.316, and the focal length f of the lens system is 4.11 mm. Therefore, 0.6<f1/f=0.81<1.0, satisfying the conditional expression (3). In addition, the refractive index n1 of the first lens 501 is 1.5247, and the curvature radius r1 of the object-side lens surface 506 of the first lens 501 is 1.154 mm. Therefore, 1.8<(n1-1)f/r1=1.87<2.5, satisfying conditional expression (4).

8A to 8C show aberration diagrams for the imaging lens shown in FIG. 7 . FIG. 8A shows spherical aberration, FIG. 8B shows astigmatism, and FIG. 8C shows distortion aberration.

【Table 4】

f=4.11, Fno=4.03

lens data Face number r j dj Nd νd Aperture stop ∞ 0.00 R1 1.154 0.75 1.5247 56.40 R2 2.636 0.41 R3 -6.224 3.11 1.5247 56.40 R4 25.748 0.62 IMA ∞

Aspheric coefficient R1 R2 R3 R4 kappa -1.0874E+00 -5.0163E+00 0.0000E+00 0.0000E+00 A ₄ 1.2063E-01 2.8418E-02 -1.6794E-01 1.0059E-02 A ₆ -6.8300E-03 8.5405E-01 -1.3217E-01 -1.3965E-02 A ₈ 3.4094E-01 2.3830E+00 1.2616E-01 2.4960E-03 A ₁₀ -3.3592E-02 3.1384E-01 4.6397E-02 -1.6400E-05 A ₁₂ 0.0000E+00 0.0000E+00 -1.3222E-02 0.0000E+00

In the present embodiment, as shown in Fig. 7 and Fig. 8, by making two groups of two lens systems with very simple structures satisfy conditional formula (3) and conditional formula (4), approximately 1.2 times of the focal length can be obtained An imaging lens that is below and very short and has good aberration performance. In addition, since all the lenses are made of resin material, the manufacturing cost can be reduced and the manufacturing is facilitated.

In addition, in the above-mentioned embodiment, the example which both the surface of the 1st lens 501 and the 2nd lens 502 are comprised with an aspheric shape was demonstrated. But it is not limited to this, and the following configuration can also be adopted, that is: at least any one of the lens surfaces 506 and 507 of the first lens 501 is an aspherical shape, and at least any one of the lens surfaces 508 and 509 of the second lens 502 is an aspherical shape.

Industrial availability

The imaging lens of the present invention has a lens system composed of two lenses, which can realize miniaturization and correct various aberrations well, and has good processability. Therefore, it is suitable for use as an imaging lens mounted in devices such as digital cameras and compact cameras.

Claims (5)

1. An imaging lens, characterized in that: It is an imaging lens composed of a lens system including at least a first lens, an aperture stop, and a second lens, wherein, The first lens is a positive meniscus lens having a convex surface on the object side lens surface, Let the focal length of the first lens be f1, the focal length of the lens system be f, and the radius of curvature of the object-side lens surface of the first lens be r1, then the lens system satisfies the following two conditions: 0.5<f1/f<1.5 ... (1), 1.0<f/r1<4.0 ... (2). 2. The imaging lens according to claim 1, characterized in that: The lens system is sequentially arranged with the first lens, the aperture stop, and the second lens from the object side, wherein, The second lens has a positive refractive index. 3. The imaging lens according to claim 1, characterized in that: The lens system is sequentially arranged with the aperture stop, the first lens, and the second lens from the object side, wherein, The second lens is a negative meniscus lens. 4. An imaging lens, characterized in that, It is an imaging lens composed of a lens system having at least an aperture stop, a first lens, and a second lens in order from the object side, wherein, The first lens is a positive meniscus lens having a convex surface on the object side lens surface, The second lens is a biconcave lens, In any one of the first lens and the second lens, at least one of the lens surfaces has an aspheric shape, If the focal length of the lens system is f, the focal length of the first lens is f1, the refractive index of the first lens is n1, and the radius of curvature of the object side of the first lens is r1, then the lens system satisfies the following two conditional expressions: 0.6<f1/f<1.0 ……(3), 1.8<(n1-1)f/r1<2.5 ... (4). 5. The imaging lens according to any one of claims 1 to 4, characterized in that: Both the first lens and the second lens are made of resin material.

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