TW201823793A - Lens assembly - Google Patents

Abstract

A lens assembly includes a first lens, a second lens, a third lens, a fourth lens, a stop, a fifth lens, a sixth lens, a seventh lens and an eighth lens, all of which are arranged in order from an object side to an image side along an optical axis. The first lens is a meniscus lens with negative refractive power. The second lens is a meniscus lens with negative refractive power. The third lens is a biconcave lens with negative refractive power. The fourth lens is a biconvex lens with positive refractive power. The fifth lens is a biconvex lens with positive refractive power. The sixth lens is with positive refractive power. The seventh lens is with negative refractive power. The eighth lens is with positive refractive power. The sixth lens and the seventh lens are cemented.

Description

Imaging lens (17)

The invention relates to an imaging lens.

Today's imaging lenses with a viewing angle of more than 200 degrees have large total lens lengths and apertures, making it difficult to meet the needs of miniaturization. Therefore, another type of imaging lens is needed to meet the requirements of large angle of view, small aperture value, and miniaturization. Characteristics.

In view of this, the main purpose of the present invention is to provide an imaging lens that has the characteristics of a large angle of view, a small aperture value, and miniaturization, but still has good optical performance.

The imaging lens of the present invention includes a first lens, a second lens, a third lens, a fourth lens, an aperture, a fifth lens, a lens in order from an object side to an image side along an optical axis The sixth lens, a seventh lens and an eighth lens. The first lens is a meniscus lens with negative refractive power. The second lens is a meniscus lens with negative refractive power. The third lens is a biconcave lens with negative refractive power. The fourth lens is a biconvex lens with positive refractive power. The fifth lens is a biconvex lens with positive refractive power. The sixth lens has positive refractive power. The seventh lens has negative refractive power. The eighth lens has positive refractive power. The sixth lens and the seventh lens are cemented with each other.

The imaging lens satisfies the following conditions: -15<f ₁ /f<f ₂ /f<f ₃ /f<-1.8; where f is the effective focal length of the imaging lens, f ₁ is the effective focal length of the first lens, f ₂ Is the effective focal length of the second lens, and f ₃ is the effective focal length of the third lens.

The imaging lens satisfies the following conditions: -0.8<f ₁₂₃ /f<-0.6; where f is the effective focal length of the imaging lens, and f ₁₂₃ is the effective focal length of the combination of the first lens, the second lens, and the third lens.

The imaging lens satisfies the following conditions: 2.4<f ₈ /f<2.8; where f is the effective focal length of the imaging lens, and f ₈ is the effective focal length of the eighth lens.

The imaging lens satisfies the following conditions: -0.8<f ₁₂₃₄ /f ₅₆₇₈ <-0.6; where f ₁₂₃₄ is the effective focal length of the combination of the first lens, the second lens, the third lens and the fourth lens, and f ₅₆₇₈ is the fifth The effective focal length of the combination of the lens, sixth lens, seventh lens and eighth lens.

The imaging lens satisfies the following conditions: 0.8<TTL/D ₁ <1.6; where, TTL is a distance between the object side of the first lens and an imaging plane on the optical axis, and D ₁ is one of the effective diameters of the first lens.

The imaging lens satisfies the following conditions: 200 degrees <FOV<240 degrees; wherein, FOV is one of the maximum viewing angles of the imaging lens.

In each of the second lens, the third lens, the fifth lens and the eighth lens, at least one surface is an aspheric surface or both surfaces are aspheric surfaces.

The third lens is a spherical lens, the first lens may further include a convex surface facing the object side and a concave surface facing the image side, and the second lens may further include a convex surface facing the object side and a concave surface facing the image side.

The first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens and the eighth lens are made of glass material.

In order to make the above objects, features, and advantages of the present invention more comprehensible, preferred embodiments are described in detail below in conjunction with the accompanying drawings.

1, 2‧‧‧ imaging lens

L11, L21‧‧‧First lens

L12, L22‧‧‧second lens

L13, L23‧‧‧third lens

L14, L24 ‧‧‧ fourth lens

L15, L25 ‧‧‧ fifth lens

L16, L26‧Sixth lens

L17, L27 ‧‧‧ seventh lens

L18, L28‧Eighth lens

ST1, ST2‧‧‧ Aperture

OF1, OF2‧‧‧ filter

OA1, OA2 ‧‧‧ optical axis

IMA1, IMA2 ‧‧‧ imaging surface

S11, S12, S13, S14, S15

S16, S17, S18, S19, S110

S111, S112, S113, S114, S115

S116, S117, S118

S21, S22, S23, S24, S25

S26, S27, S28, S29, S210

S211, S212, S213, S214, S215

S216, S217, S218

FIG. 1 is a schematic diagram of a lens configuration according to the first embodiment of the imaging lens of the present invention.

Figure 2A is a longitudinal aberration diagram of the imaging lens of Figure 1.

Figure 2B is a field curvature diagram of the imaging lens of Figure 1.

Figure 2C is a distortion diagram of the imaging lens of Figure 1.

FIG. 3 is a schematic diagram of a lens configuration according to a second embodiment of the imaging lens of the present invention.

Figure 4A is a longitudinal aberration diagram of the imaging lens of Figure 3.

Figure 4B is a field curvature diagram of the imaging lens of Figure 3.

Figure 4C is a distortion diagram of the imaging lens of Figure 3.

Please refer to FIG. 1, which is a schematic diagram of a lens configuration according to the first embodiment of the imaging lens of the present invention. The imaging lens 1 includes a first lens L11, a second lens L12, a third lens L13, a fourth lens L14, an aperture ST1, a first lens in order from an object side to an image side along an optical axis OA1 Five lenses L15, a sixth lens L16, a seventh lens L17, an eighth lens L18 and a filter OF1. When imaging, the light from the object side is finally imaged on an imaging surface IMA1.

The first lens L11 is a meniscus lens with a negative refractive power and is made of glass material. The object side S11 is convex, the image side S12 is concave, and both the object side S11 and the image side S12 are spherical surfaces.

The second lens L12 is a meniscus lens with a negative refractive power made of glass material. Its object side S13 is convex, the image side S14 is concave, and both the object side S13 and the image side S14 are aspherical surfaces.

The third lens L13 is a biconcave lens with a negative refractive power and is made of glass material. Its object side S15 is concave, the image side S16 is concave, and both the object side S15 and the image side S16 are aspherical surfaces.

The fourth lens L14 is a biconvex lens with positive refractive power made of glass material, its object side S17 is convex, the image side S18 is convex, and both the object side S17 and the image side S18 are spherical surfaces.

The fifth lens L15 is a biconvex lens with positive refractive power made of glass material. Its object side S110 is convex, the image side S111 is convex, and both the object side S110 and the image side S111 are aspherical surfaces.

The sixth lens L16 is a biconvex lens with a positive refractive power made of glass material, its object side S112 is convex, the image side S113 is convex, and both the object side S112 and the image side S113 are spherical surfaces.

The seventh lens L17 is a biconcave lens made of glass material with negative refractive power. Its object side S113 is concave, the image side S114 is concave, and both the object side S113 and the image side S114 are spherical surfaces.

The sixth lens L16 and the seventh lens L17 are cemented, which means that there is no air gap between the sixth lens L16 and the seventh lens L17.

The eighth lens L18 is a biconvex lens with positive refractive power made of glass material. Its object side S115 is convex, the image side S116 is convex, and both the object side S115 and the image side S116 are aspherical surfaces.

The object side S117 and the image side S118 of the filter OF1 are both flat.

In addition, the imaging lens 1 in the first embodiment satisfies at least one of the following conditions: -15<f1 ₁ /f1<f1 ₂ /f1<f1 ₃ /f1<-1.8 (1)

-0.8<f1 ₁₂₃ /f1<-0.6 (2)

2.4<f1 ₈ /f1<2.8 (3)

-0.8<f1 ₁₂₃₄ /f1 ₅₆₇₈ <-0.6 (4)

0.8<TTL1/D1 ₁ <1.6 (5)

200 degrees<FOV1<240 degrees (6)

Where f1 is the effective focal length of the imaging lens 1, f1 ₁ is the effective focal length of the first lens L11, f1 ₂ is the effective focal length of the second lens L12, f1 ₃ is the effective focal length of the third lens L13, and f1 ₈ is the eighth lens The effective focal length of L18, f1 ₁₂₃ is the effective focal length of the combination of the first lens L11, the second lens L12 and the third lens L13, f1 ₁₂₃₄ is the first lens L11, the second lens L12, the third lens L13 and the fourth lens L14 The effective focal length of the combination of f1 ₅₆₇₈ is the effective focal length of the combination of the fifth lens L15, the sixth lens L16, the seventh lens L17 and the eighth lens L18, and the TTL1 is the object side S11 of the first lens L11 to the imaging plane IMA1 The distance between the axes OA1, D1 ₁ is the effective diameter of the first lens L11, and FOV1 is the maximum angle of view of the imaging lens 1.

Among them, the condition (1) can also be expressed as -15<f1 ₁ /f1<-1.8, -15<f1 ₂ /f1<-1.8, -15<f1 ₃ /f1<-1.8, so f1 ₃ >f1 ₂ , F1 ₂ >f1 ₁ , f1 ₃ >f1 ₁ , that is, f1 ₃ >f1 ₂ >f1 ₁ .

With the above lens, aperture and the design satisfying condition (1) to condition (6), the imaging lens 1 can increase the angle of view, reduce the aperture value, effectively shorten the total lens length, and effectively correct aberrations.

Table 1 is a table of related parameters of each lens of the imaging lens 1 in FIG. 1. The data in Table 1 shows that the effective focal length of the imaging lens 1 of the first embodiment is equal to 1.26 mm, the aperture value is equal to 2.4, and the total lens length is equal to 19.5 mm. The maximum viewing angle is equal to 235 degrees.

The aspherical surface concave degree z of each lens in Table 1 is obtained by the following formula: z=ch ² /{1+[1-(k+1)c ² h ² ] ^1/2 }+Ah ⁴ +Bh ⁶ + Ch ⁸ +Dh ¹⁰ +Eh ¹² +Fh ¹⁴ +Gh ¹⁶

Where: c: curvature; h: vertical distance from any point on the lens surface to the optical axis; k: conic coefficient; A~G: aspherical coefficient.

Table 2 is the related parameter table of the aspherical surface of each lens in Table 1, where k is the conic constant and A~G are the aspherical coefficients.

The imaging lens of Example 1, the effective focal distance f1 = 1.26mm first embodiment, the effective focal length of the first lens L11 f1 ₁ = -14.38mm, a second lens L12 of the effective focal length f1 ₂ = -4.27mm, the third lens L13 Effective focal length f1 ₃ = -2.79 mm, effective focal length f1 _{8 of the} eighth lens L18 = 3.19 mm, effective focal length f1 ₁₂₃ of the combination of the first lens L11, the second lens L12, and the third lens L13 = -0.98 mm, the first The effective focal length of the combination of the lens L11, the second lens L12, the third lens L13 and the fourth lens L14 f1 ₁₂₃₄ = -2.74mm, the combination of the fifth lens L15, the sixth lens L16, the seventh lens L17 and the eighth lens L18 The effective focal length f1 ₅₆₇₈ = 3.47mm, the distance between the object side S11 of the first lens L11 to the imaging plane IMA1 on the optical axis OA1 TTL1 = 19.5mm, the effective diameter D1 _{1 of the} first lens L11 = 22.6mm, the maximum angle of view is equal to 235 degree. From the above data, f1 ₁ /f1=-11.41, f1 ₂ /f1=-3.39, f1 ₃ /f1=-2.21, f1 ₁₂₃ /f1=-0.78, f1 ₈ /f1=2.53, f1 ₁₂₃₄ /f1 ₅₆₇₈ = -0.789, TTL1/D1 ₁ =0.86, FOV1=235 degrees, all can meet the requirements of the above conditions (1) to (6).

In addition, the optical performance of the imaging lens 1 of the first embodiment can also meet the requirements, which can be seen from FIGS. 2A to 2C. Shown in FIG. 2A is a longitudinal aberration (Longitudinal Aberration) diagram of the imaging lens 1 of the first embodiment. Shown in FIG. 2B is a field curvature diagram of the imaging lens 1 of the first embodiment. Shown in FIG. 2C is a distortion diagram of the imaging lens 1 of the first embodiment.

As can be seen from FIG. 2A, the imaging lens 1 of the first embodiment has a longitudinal aberration value between -0.012 mm and 0.016 mm for light rays with wavelengths of 0.436 μm, 0.486 μm, 0.546 μm, 0.588 μm, and 0.656 μm. between.

It can be seen from FIG. 2B that the imaging lens 1 of the first embodiment has a wavelength of 0.436 μm, 0.486 μm, 0.546 μm, 0.588 μm, and 0.656 μm in the direction of the meridian (Tangential) and sagittal (Sagittal). The curvature of field is between -0.005mm and 0.05mm.

It can be seen from Figure 2C (the five lines in the figure almost overlap, so that there is only one line), the imaging lens 1 of the first embodiment has a pair of wavelengths of 0.436 μm, 0.486 μm, 0.546 μm, 0.588 μm, 0.656 The distortion produced by μm light is between -16% and 0%.

It is obvious that the longitudinal aberration, field curvature, and distortion of the imaging lens 1 of the first embodiment can be effectively corrected, so as to obtain better optical performance.

Please refer to FIG. 3, which is a schematic diagram of a lens configuration according to a second embodiment of the imaging lens of the present invention. The imaging lens 2 includes a first lens L21, a second lens L22, a third lens L23, a fourth lens L24, an aperture ST2, a first lens in order from an object side to an image side along an optical axis OA2 Five lenses L25, a sixth lens L26, a seventh lens L27, an eighth lens L28 and a filter OF2. When imaging, the light from the object side is finally imaged on an imaging surface IMA2.

The first lens L21 is a meniscus lens with negative refractive power and is made of glass material. Its object side S21 is convex, the image side S22 is concave, and both the object side S21 and the image side S22 are spherical surfaces.

The second lens L22 is a meniscus lens with negative refractive power made of glass material. Its object side S23 is convex, the image side S24 is concave, and both the object side S23 and the image side S24 are aspherical surfaces.

The third lens L23 is a biconcave lens made of glass material with negative refractive power, its object side S25 is concave, the image side S26 is concave, and both the object side S25 and the image side S26 are spherical surfaces.

The fourth lens L24 is a biconvex lens with positive refractive power made of glass material, its object side S27 is convex, the image side S28 is convex, and both the object side S27 and the image side S28 are spherical surfaces.

The fifth lens L25 is a biconvex lens with positive refractive power made of glass material. Its object side S210 is convex, the image side S211 is convex, and both the object side S210 and the image side S211 are aspherical surfaces.

The sixth lens L26 is a biconvex lens with positive refractive power made of glass material. The object side S212 is convex, the image side S213 is convex, and both the object side S212 and the image side S213 are spherical surfaces.

The seventh lens L27 is a biconcave lens made of glass material with negative refractive power. Its object side S213 is concave, the image side S214 is concave, and both the object side S213 and the image side S214 are spherical surfaces.

The sixth lens L26 and the seventh lens L27 are cemented, which means that there is no air gap between the sixth lens L26 and the seventh lens L27.

The eighth lens L28 is a biconvex lens with positive refractive power made of glass material. Its object side S215 is convex, the image side S216 is convex, and both the object side S215 and the image side S216 are aspherical surfaces.

The object side S217 and the image side S218 of the filter OF2 are both flat.

In addition, the imaging lens 2 in the second embodiment satisfies at least one of the following conditions: -15<f2 ₁ /f2<f2 ₂ /f2<f2 ₃ /f2<-1.8 (7)

-0.8<f2 ₁₂₃ /f2<-0.6 (8)

2.4<f2 ₈ /f2<2.8 (9)

-0.8<f2 ₁₂₃₄ /f2 ₅₆₇₈ <-0.6 (10)

0.8<TTL2/D2 ₁ <1.6 (11)

200 degrees<FOV2<240 degrees (12)

The definitions of f2, f2 ₁ , f2 ₂ , f2 ₃ , f2 ₈ , f2 ₁₂₃ , f2 ₁₂₃₄ , f2 ₅₆₇₈ , TTL2, D2 ₁ and FOV2 are the same as f1, f1 ₁ , f1 ₂ , f1 ₃ , f1 in the first embodiment _8. The definitions of f1 ₁₂₃ , f1 ₁₂₃₄ , f1 ₅₆₇₈ , TTL1, D1 ₁ and FOV1 are the same, and will not be repeated here.

Among them, the condition (7) can also be expressed as -15<f2 ₁ /f2<-1.8, -15<f2 ₂ /f2<-1.8, -15<f2 ₃ /f2<-1.8, so f2 ₃ >f2 ₂ , F2 ₂ >f2 ₁ , f2 ₃ >f2 ₁ , that is, f2 ₃ >f2 ₂ >f2 ₁ .

With the above lens and aperture and the design satisfying condition (7) to condition (12), the imaging lens 2 can increase the angle of view, reduce the aperture value, effectively shorten the total lens length, and effectively correct aberrations.

Table 3 is a table of related parameters of each lens of the imaging lens 2 in FIG. 3. The data in Table 3 shows that the effective focal length of the imaging lens 2 of the second embodiment is equal to 1.63 mm, the aperture value is equal to 2.4, and the total lens length is equal to 19.0 mm. The maximum viewing angle is equal to 207 degrees.

The aspherical surface depression degree z of each lens in Table 3 is obtained by the following formula: z=ch ² /{1+[1-(k+1)c ² h ² ] ^1/2 }+Ah ⁴ +Bh ⁶ + Ch ⁸ +Dh ¹⁰ +Eh ¹² +Fh ¹⁴ +Gh ¹⁶

Where: c: curvature; h: vertical distance from any point on the lens surface to the optical axis; k: conic coefficient; A~G: aspherical coefficient.

Table 4 is the related parameter table of the aspherical surface of each lens in Table 3, where k is the conic constant and A~G are the aspherical coefficients.

A second imaging lens of Embodiment 2, the effective focal length f2 = 1.63mm, an effective focal length of the first lens L21 f2 ₁ = -7.91mm, the effective focal length of the second lens L22 f2 ₂ = -7.04mm, the third lens L23 Effective focal length f2 ₃ =-3.17mm, effective focal length f2 ₈ =4.27mm of the eighth lens L28, effective focal length f2 ₁₂₃ =-1.11mm of the combination of the first lens L21, the second lens L22 and the third lens L23, the first The effective focal length f2 of the combination of the lens L21, the second lens L22, the third lens L23 and the fourth lens L24 ₁₂₃₄ = -2.56mm, the combination of the fifth lens L25, the sixth lens L26, the seventh lens L27 and the eighth lens L28 The effective focal length f2 ₅₆₇₈ =3.99mm, the distance from the object side S21 of the first lens L21 to the imaging surface IMA2 on the optical axis OA2 is TTL2=19.0mm, the effective diameter of the first lens L21 D2 ₁ =12.5mm, the maximum angle of view is equal to 207 degree. From the above data, f2 ₁ /f2=-4.84, f2 ₂ /f2=-4.31, f2 ₃ /f2=-1.94, f2 ₁₂₃ /f2=-0.68, f2 ₈ /f2=2.62, f2 ₁₂₃₄ /f2 ₅₆₇₈ = -0.64, TTL2/D2 ₁ = 1.52, FOV2 = 207 degrees, can meet the requirements of the above conditions (7) to (12).

In addition, the optical performance of the imaging lens 2 of the second embodiment can also meet the requirements, which can be seen from FIGS. 4A to 4C. FIG. 4A is a longitudinal aberration (Longitudinal Aberration) diagram of the imaging lens 2 of the second embodiment. Fig. 4B shows a field curvature diagram of the imaging lens 2 of the second embodiment. Shown in FIG. 4C is a distortion diagram of the imaging lens 2 of the second embodiment.

It can be seen from FIG. 4A that the imaging lens 2 of the second embodiment has a longitudinal aberration value between -0.016 mm and 0.013 mm for light rays with wavelengths of 0.436 μm, 0.486 μm, 0.546 μm, 0.587 μm, and 0.656 μm. between.

As can be seen from FIG. 4B, the imaging lens 2 of the second embodiment has a wavelength of 0.436 μm, 0.486 μm, 0.546 μm, 0.587 μm, and 0.656 μm in the meridional (Tangential) direction and sagittal (Sagittal) direction. The curvature of field is between -0.03mm and 0.025mm.

It can be seen from Figure 4C (the five lines in the figure almost overlap, so that there seems to be only one line), the imaging lens 2 of the second embodiment has a pair of wavelengths of 0.436 μm, 0.486 μm, 0.546 μm, 0.587 μm, 0.656 The distortion produced by μm light is between -11% and 0%.

It is obvious that the longitudinal aberration, field curvature, and distortion of the imaging lens 2 of the second embodiment can be effectively corrected to obtain better optical performance.

Claims (10)

An imaging lens, along an optical axis, from an object side to an image side in sequence includes: a first lens having negative refractive power, the first lens is a meniscus lens; a second lens having negative refractive power, the second The lens is a meniscus lens; a third lens has negative refractive power, the third lens is a biconcave lens; a fourth lens has positive refractive power, the fourth lens is a biconvex lens; an aperture; a fifth lens has positive refractive power, The fifth lens is a biconvex lens; a sixth lens has positive refractive power; a seventh lens has negative refractive power; and an eighth lens has positive refractive power; the sixth lens and the seventh lens are cemented with each other. The imaging lens as described in item 1 of the patent application scope, wherein the imaging lens meets the following conditions: -15<f ₁ /f<f ₃ /f<f ₃ /f<-1.8; where f is the imaging lens Effective focal length, f _{1 is} the effective focal length of the first lens, f _{2 is} the effective focal length of the second lens, and f _{3 is} the effective focal length of the third lens. The imaging lens as described in item 1 of the patent application scope, wherein the imaging lens satisfies the following conditions: -0.8<f ₁₂₃ /f<-0.6; where f is the effective focal length of the imaging lens and f _{123 is} the first lens , An effective focal length of the combination of the second lens and the third lens. The imaging lens as described in item 1 of the patent scope, wherein the imaging lens satisfies the following conditions: 2.4<f ₈ /f<2.8; where f is the effective focal length of the imaging lens and f _{8 is} the effective of the eighth lens focal length. The imaging lens as described in item 1 of the patent application scope, wherein the imaging lens satisfies the following conditions: -0.8<f ₁₂₃₄ /f ₅₆₇₈ <-0.6; wherein, f _{1234 is} the first lens, the second lens, the first One effective focal length of the combination of the three lenses and the fourth lens, f _{5678 is} an effective focal length of the combination of the fifth lens, the sixth lens, the seventh lens, and the eighth lens. The imaging lens as described in item 1 of the patent application scope, wherein the imaging lens satisfies the following conditions: 0.8<TTL/D ₁ <1.6; wherein, TTL is the object side of the first lens to an imaging plane on the optical axis One pitch, D _{1 is} one of the effective diameter of the first lens. The imaging lens as described in item 1 of the patent application scope, wherein the imaging lens satisfies the following conditions: 200 degrees <FOV<240 degrees; wherein, FOV is one of the maximum viewing angles of the imaging lens. The imaging lens as described in item 1 of the patent application scope, wherein at least one surface of each of the second lens, the third lens, the fifth lens, and the eighth lens is an aspheric surface or two surfaces All are aspherical surfaces. The imaging lens as described in item 1 of the patent application scope, wherein the third lens is a spherical lens, the first lens further includes a convex surface facing the object side and a concave surface facing the image side, and the second lens further includes a convex surface Towards the object side and a concave surface towards the image side. The imaging lens as described in item 1 of the patent application scope, wherein the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, and the The eighth lens is made of glass.