TW201704803A - Three-piece type imaging lens which satisfies the condition of f2/f3 < 1.55, where f2 and f3 are focal lengths of a second lens and a third lens, respectively - Google Patents

Abstract

A three-piece type imaging lens includes, arranged along an optical axis in sequence from an object side to an imaging plane: a first lens which is a convex-concave lens having a negative refractive power, with a convex surface facing toward the object side and a concave surface facing toward the imaging surface, at least one lens surface of the first lens being an aspheric surface; a second lens, which is a concave-convex lens having a positive refractive power, with a convex surface facing toward the object side and a concave surface facing toward the imaging plane, at least one lens surface of the second lens being an aspheric surface; and a third lens, which is a biconvex lens having a positive refractive power, and at least one lens surface thereof being an aspheric surface. In addition, the three-piece imaging lens further satisfies the following condition: f2/f3 < 1.55, where f2 and f3 are the focal lengths of the second lens and the third lens, respectively.

Description

Three-chip camera lens

The invention relates to an optical lens; in particular to a three-piece imaging lens.

The lens structure is widely used in camera lens groups in electronic products such as mobile phones, notebook computers, and cameras. The photosensitive elements in the aforementioned imaging lens group can be mainly classified into a photosensitive coupled device (CCD) and a complementary metal oxide semiconductor (CMOS), wherein CMOS has low cost and low power consumption. The high integration makes CMOS gradually become the mainstream of mobile devices in the market. In addition, due to the advancement of semiconductor process technology, the size of the pixel can be greatly reduced. This factor allows the photosensitive element to provide a higher pixel image, but also reduces the amount of light, so that the amount of light is reduced, and the lens system is inevitable. Provide higher brightness to reduce the effects of noise.

In recent years, as such electronic products have been continuously developed to be lighter, thinner, shorter, and smaller, and at the same time, they must have higher performance, and the volume of the above-mentioned camera lens group applied to electronic products has also been greatly reduced. Since the pixels of the image capturing device are higher and higher, the lens group used for the image capturing device can also have higher optical performance, so that the image capturing device can achieve high resolution and high contrast. . In other words, miniaturization and high optical performance are two essential elements for the lens of imaging equipment.

In view of the above, an object of the present invention is to provide a three-piece type The camera lens reduces the overall lens volume while providing good optical performance.

In order to achieve the above object, the three-piece film provided by the present invention The image lens includes a first lens, a second lens, an aperture, and a third lens sequentially arranged from an object side to an imaging surface and along an optical axis. The first lens is a convex-concave lens having a negative refractive power, and the convex surface faces the object side, and the concave surface faces the imaging surface, at least one mirror surface of the first lens is an aspherical surface; and the second lens has a positive refractive power a meniscus lens having a convex surface facing the object side and a concave surface facing the imaging surface, wherein at least one mirror surface of the second lens is an aspherical surface; the third lens is a lenticular lens having positive refractive power, and at least one mirror surface is Aspherical surface. In addition, the three-piece imaging lens further satisfies the following condition: 1.3<f2/f3<1.55; wherein f2 is the focal length of the second lens; and f3 is the focal length of the third lens.

Through the above optical design, the three-piece camera of the present invention The head has a small size, wide angle, small optical distortion and high optical performance.

1~3‧‧‧Three-chip camera lens

L1‧‧‧ first lens

L2‧‧‧ second lens

L3‧‧‧ third lens

STO‧‧‧ aperture

CF‧‧‧Filter

Im‧‧‧ imaging surface

S1~S8‧‧‧Mirror

1 is a lens diagram of a first preferred embodiment of the present invention; FIG. 2A is a field curvature diagram of a first preferred embodiment of the present invention; FIG. 2B is a distortion diagram of a first preferred embodiment of the present invention; FIG. 3 is a lens diagram of a second preferred embodiment of the present invention; FIG. 4A is a field curvature diagram of a second preferred embodiment of the present invention; FIG. 4B is a second aspect of the present invention; FIG. 4C is a longitudinal chromatic aberration diagram of a second preferred embodiment of the present invention; FIG. 5 is a lens diagram of a third preferred embodiment of the present invention; 6A is a field curvature diagram of a third preferred embodiment of the present invention; FIG. 6B is a distortion diagram of a third preferred embodiment of the present invention; and FIG. 6C is a longitudinal chromatic aberration diagram of a third preferred embodiment of the present invention.

In order that the present invention may be more clearly described, the preferred embodiments are described in detail with reference to the drawings.

Referring to FIG. 1 , a three-chip imaging lens 1 according to a first preferred embodiment of the present invention includes a first lens arranged along an optical axis Z and sequentially arranged from an object side to an imaging surface Im. L1, a second lens L2, an aperture STO, and a third lens L3. In addition, depending on the requirements of use, an optical filter CF may be disposed between the third lens L3 and the imaging surface Im to filter out unnecessary noise light, thereby improving optical performance. The purpose. The first lens L1 is a convex-concave lens having a negative refractive power, and the convex surface faces the object side, and the concave surface faces the imaging surface Im, so that the three-piece imaging lens 1 has a wide-angle optical characteristic. In addition, at least one mirror surface of the first lens L1 is an aspherical surface, and in the embodiment, the two mirror surfaces S1 and S2 of the first lens L1 are aspherical surfaces. Among them, the aspherical design is intended to effectively correct the distortion problem that the three-piece imaging lens 1 is prone to in wide-angle optical design.

The second lens L2 is a meniscus lens having a positive refractive power, the convex surface of which faces the object side, and the concave surface faces the imaging surface Im. At least one mirror surface of the second lens L2 is an aspherical surface. In the embodiment, the two mirror surfaces S3 and S4 of the second lens L2 are aspherical surfaces.

The third lens L3 is a lenticular lens having a positive refractive power, and at least one mirror surface is an aspherical surface. In the embodiment, the two mirror surfaces S5 and S6 of the third lens L3 are aspherical surfaces.

In addition, in addition to the structural design of the lenses L1 to L3 described above, in the present embodiment, the three-chip imaging lens further satisfies the following conditional formula: (1) 1.3 < f2 / f3 < 1.55; (2) 0.17 < f/TTL<0.18; (3)0.32<f2/TTL<0.35; (4)1.0<|f1/f|<1.2; (5)1.8<f2/f<2; (6)1.3<f3/f< 1.5; (7)|vd1-vd2|<34; wherein f is the focal length of the system of the three-piece imaging lens 1; f1 is the focal length of the first lens L1; f2 is the focal length of the second lens L2; f3 is The focal length of the third lens L3; TTL is the total length of the system of the three-piece imaging lens 1; vd1 is the Abbe's coefficient of the first lens L1; and vd2 is the Abbe's coefficient of the second lens L2.

In order to effectively improve the optical performance of the three-piece imaging lens 1, the system focal length f of the three-piece imaging lens 1 of the first preferred embodiment of the present invention, the radius of curvature R of the optical axis Z of each lens surface, and the respective mirror surfaces The distance D from the next mirror (or imaging surface) on the optical axis Z, the refractive index Nd of each lens, and the Abbe's coefficient Vd of each lens are as shown in Table 1:

In each lens of this embodiment, the surface depression z of the aspherical surfaces S1 to S6 is obtained by the following formula:

Where: z: the degree of depression of the aspheric surface; c: the reciprocal of the radius of curvature; h: the aperture radius of the surface; k: the conic coefficient; α 2 ~ α 8: the various order coefficients of the aperture radius h of the surface.

In this embodiment, the aspheric coefficient k of each aspheric surface and the coefficient α 2~α 8 of each order are as shown in Table 2:

In addition, the detailed data of the above three conditions of the three-piece imaging lens 1 of the present embodiment is as shown in Table 3:

Thereby, through the above lenses L1 ~ L3 and the aperture STO The three-piece imaging lens 1 of the present embodiment has a wide-angle function and at the same time has the advantages of a short total system length, and can shorten the volume of the overall lens. In addition, as shown in FIG. 2A to FIG. 2C, the three-piece imaging lens 1 of the present embodiment can also meet the requirements in image quality. It can be seen from the field curvature diagram shown in FIG. 2A that the maximum field curvature of the three-piece imaging lens 1 of the present embodiment does not exceed -0.04 mm and 0.04 mm; as can be seen from the distortion diagram shown in FIG. 2B, The maximum distortion of the three-piece imaging lens 1 of the present embodiment is not more than -30% and 15%; as shown by the longitudinal aberration diagram of the pupil radius of 0.0769 mm shown in FIG. 2C, The longitudinal aberration of the three-piece imaging lens 1 of the embodiment does not exceed -0.02 mm to 0.02 mm. Thus, the high optical performance of the three-piece image pickup lens 1 of the present embodiment can be seen.

The above is a three-piece photograph of the first embodiment of the present invention. Image Lens 1; According to the technique of the present invention, a three-chip imaging lens 2 according to a second embodiment of the present invention will be described below with reference to FIG.

The three-piece camera lens 2 of the second preferred embodiment of the present invention is the same as The sample includes a first lens L1, a second lens L2, an aperture STO, a third lens L3 and a filter CF arranged along an optical axis Z and sequentially from an object side to an imaging surface Im. The first lens L1 is a convex-concave lens having a negative refractive power, and the convex surface faces the object side, and the concave surface faces the imaging surface Im, so that the three-piece imaging lens 2 has wide-angle optical characteristics. The at least one mirror surface of the first lens L1 is an aspherical surface. In the embodiment, the two mirror surfaces S1 and S2 of the first lens L1 are aspherical surfaces. Among them, aspherical The purpose of the design is to effectively correct the distortion problem that the three-piece imaging lens 2 is prone to in wide-angle optical design.

The second lens L2 is a meniscus lens having a positive refractive power, the convex surface of which faces the object side, and the concave surface faces the imaging surface Im. At least one mirror surface of the second lens L2 is an aspherical surface. In the embodiment, the two mirror surfaces S3 and S4 of the second lens L2 are aspherical surfaces.

The third lens L3 is a lenticular lens having a positive refractive power, and at least one mirror surface is an aspherical surface. In the embodiment, the two mirror surfaces S5 and S6 of the third lens L3 are aspherical surfaces.

In addition, in addition to the structural design of the lenses L1 to L3 described above, in the present embodiment, the three-piece imaging lens 2 further satisfies the following conditional formula: (1) 1.3 < f2 / f3 <1.55; (2) 0.17 <f/TTL<0.18;(3)0.32<f2/TTL<0.35;(4)1.0<|f1/f|<1.2;(5)1.8<f2/f<2;(6)1.3<f3/f<1.5;(7)|vd1-vd2|<34; in order to effectively improve the optical performance of the three-piece imaging lens 2, the system focal length f of the three-piece imaging lens 2 of the first preferred embodiment of the present invention, each lens The radius of curvature R of the optical axis Z of the surface, the distance D between each mirror surface and the next mirror surface (or imaging surface) on the optical axis Z, the refractive index Nd of each lens, and the Abbe's coefficient Vd of each lens, as shown in Table 4 Shown as follows:

In each lens of this embodiment, the surface depression degree z of the aspherical surfaces S1 to S6 is also obtained by the following formula:

In this embodiment, the aspherical coefficient k of each aspherical surface and the respective order coefficients α 2 to α 8 are as shown in Table 5:

In addition, the detailed data of the above three conditions of the three-piece imaging lens 2 of the present embodiment is as shown in Table 6:

Thereby, through the above lenses L1 ~ L3 and the aperture STO The three-piece imaging lens 2 of the present embodiment has the function of wide-angle, and at the same time has the advantages of a short total system length, and can shorten the volume of the overall lens. In addition, referring to FIG. 4A to FIG. 4C, the three-piece imaging lens 2 of the present embodiment can also meet the requirements in image quality. It can be seen from the field curvature diagram shown in FIG. 4A that the maximum field curvature of the three-piece imaging lens 2 of the present embodiment does not exceed -0.04 mm and 0.04 mm; as can be seen from the distortion diagram shown in FIG. 4B, The maximum distortion of the three-piece imaging lens 2 of the present embodiment does not exceed -50% and 15%; as shown by the longitudinal aberration diagram of the pupil radius of 0.0698 mm shown in FIG. 4C, The longitudinal aberration of the three-piece imaging lens 2 of the embodiment does not exceed -0.02 mm to 0.02 mm. Thus, the high optical performance of the three-piece imaging lens 2 of the present embodiment can be seen.

In addition, in addition to the three-piece imaging lenses 1 and 2 of the first embodiment and the second embodiment, FIG. 5 shows a three-piece imaging lens 3 according to a third preferred embodiment of the present invention. 3 also includes a first lens L1, a second lens L2, an aperture STO, a third lens L3, and a filter CF arranged along an optical axis Z and sequentially from an object side to an imaging surface Im. . Wherein: the first lens L1 is a convex-concave lens having a negative refractive power, the convex surface faces the object side, and the concave surface faces the imaging surface Im, whereby the three-piece imaging lens 3 has a wide-angle optical characteristic. The at least one mirror surface of the first lens L1 is an aspherical surface. In the embodiment, the two mirror surfaces S1 and S2 of the first lens L1 are aspherical surfaces. Among them, the aspherical design is intended to effectively correct the distortion problem that is likely to occur in the wide-angle optical design of the three-piece imaging lens 3.

The second lens L2 is a meniscus lens having positive refractive power. The convex surface faces the object side, and the concave surface faces the image forming surface Im. At least one mirror surface of the second lens L2 is an aspherical surface. In the embodiment, the two mirror surfaces S3 and S4 of the second lens L2 are aspherical surfaces.

The third lens L3 is a lenticular lens having a positive refractive power, and at least one mirror surface is an aspherical surface. In the embodiment, the two mirror surfaces S5 and S6 of the third lens L3 are aspherical surfaces.

In addition to the above-described structural design of the lenses L1 to L3, in the present embodiment, the three-piece imaging lens 3 also satisfies the following conditional formula: (1) 1.3 < f2 / f3 <1.55; (2) 0.17 < f /TTL<0.18;(3)0.32<f2/TTL<0.35;(4)1.0<|f1/f|<1.2;(5)1.8<f2/f<2;(6)1.3<f3/f<1.5(7)|vd1-vd2|<34; in order to effectively improve the optical performance of the three-piece imaging lens 3, the system focal length f of the three-piece imaging lens 3 of the third preferred embodiment of the present invention, and the surface of each lens The radius of curvature R of the optical axis Z passing through, the distance D between each mirror surface and the next mirror surface (or imaging surface) on the optical axis Z, the refractive index Nd of each lens, and the Abbe's coefficient Vd of each lens are as shown in Table 7. :

In each lens of this embodiment, the surface depression degree z of the aspherical surfaces S1 to S6 is also obtained by the following formula:

In this embodiment, the aspherical coefficient k of each aspheric surface and the coefficient α 2 to α 8 of each order are as shown in Table 8:

In addition, the detailed data of the above three conditions for the three-piece imaging lens 3 of the present embodiment is as shown in Table IX:

Thereby, through the above lenses L1 ~ L3 and the aperture STO The three-piece imaging lens 3 of the present embodiment has the function of wide-angle, and at the same time has the advantages of a short total system length, and can shorten the volume of the overall lens. In addition, as shown in FIGS. 6A to 6C, the three-piece imaging lens 3 of the present embodiment can also meet the requirements in image quality. It can be seen from the field curvature diagram shown in FIG. 6A that the maximum field curvature of the three-piece imaging lens 3 of the present embodiment does not exceed -0.04 mm and 0.04 mm; as can be seen from the distortion diagram shown in FIG. 6B, The maximum distortion of the three-piece imaging lens 3 of the present embodiment does not exceed -40% and 15%; as shown by the longitudinal aberration diagram of the pupil radius of 0.0758 mm shown in Fig. 6C, The longitudinal aberration of the three-piece imaging lens 3 of the embodiment does not exceed -0.02 mm to 0.02 mm. Thus, the high optical efficiency of the three-piece imaging lens 3 of the present embodiment can be seen.

The mirrors of the respective lenses of the camera lens of the above embodiment are The design of the aspherical surface is adopted, and the aspherical design can mainly achieve the elimination of optical aberrations (such as spherical aberration, distortion), reduce the number of lenses used, and the volume and weight of the small overall lens group. In other practical implementations, one of the mirror surfaces of the first lens, one of the mirror surfaces of the second lens, and/or one of the mirror surfaces of the third lens may also adopt a spherical surface design, and is not limited to the above embodiment.

Each lens of the camera lens of the above embodiment is made of plastic Made of material, and the filter is made of glass. Among them, the advantage of the lens injection molding is that the quality of the plastic lens is light, which is beneficial to the weight reduction of the lens, and the automatic production efficiency of the plastic injection lens is high, and the cost is low. In other practical implementations, the material of each lens may of course be made of a material other than plastic, such as glass.

The above is only a preferred embodiment of the present invention, and equivalent changes to the scope of the present invention and the scope of the patent application are intended to be included in the scope of the present invention.

1‧‧‧Three-chip camera lens

L1‧‧‧ first lens

L2‧‧‧ second lens

L3‧‧‧ third lens

STO‧‧‧ aperture

CF‧‧‧Filter

Im‧‧‧ imaging surface

S1~S8‧‧‧Mirror

Claims (8)

A three-piece imaging lens comprising: an object side to an imaging surface and sequentially arranged along an optical axis: a first lens, which is a convex-concave lens having a negative refractive power, and a convex surface thereof faces the object side, and The concave surface faces the imaging surface, and at least one mirror surface of the first lens is an aspherical surface; a second lens is a convex lens having positive refractive power, and the convex surface faces the object side, and the concave surface faces the imaging surface, the first surface At least one mirror surface of the two lenses is an aspherical surface; an aperture; and a third lens is a lenticular lens having positive refractive power, and at least one mirror surface is an aspherical surface; in addition, the three-piece imaging lens further satisfies the following conditions : 1.3 < f2 / f3 < 1.55; wherein f2 is the focal length of the second lens; f3 is the focal length of the third lens. The three-piece imaging lens of claim 1, wherein each of the mirrors of each of the lenses is an aspherical surface. The three-chip imaging lens according to claim 1, wherein the three-chip imaging lens further satisfies the following condition: 0.17<f/TTL<0.18; wherein f is a system focal length of the three-chip imaging lens; The total length of the system of the three-piece camera lens. The three-chip imaging lens according to claim 1, wherein the three-chip imaging lens further satisfies the following condition: 0.32 < f2 / TTL < 0.35; wherein TTL is the total length of the system of the three-chip imaging lens. The three-chip imaging lens of claim 1, wherein the three-piece imaging lens further satisfies the following condition: 1.0<|f1/f|<1.2; wherein f1 is a focal length of the first lens; f is the third The focal length of the system of the film camera lens. The three-chip imaging lens according to claim 1, wherein the three-piece imaging lens further satisfies the following condition: 1.8 < f2 / f < 2; wherein f is a system focal length of the three-piece imaging lens. The three-chip imaging lens according to claim 1, wherein the three-chip imaging lens further satisfies the following condition: 1.3 < f3 / f < 1.5; wherein f is a system focal length of the three-piece imaging lens. The three-chip imaging lens of claim 3, wherein the three-chip imaging lens further satisfies the following condition: |vd1-vd2|<34; wherein vd1 is an Abbe coefficient of the first lens; vd2 is the Abbe's coefficient of the second lens.