Lens assembly

Abstract

To provide a lens assembly with a short total lens length, high resolution, optical image stabilization, and excellent optical performance.SOLUTION: A lens assembly includes a first lens group, a second lens group, and a third lens group. The first lens group has positive refractive power and at least four lenses, the lenses are arranged in order from an object side to an image side along an optical axis, the lens closest to the object side among the lenses has a convex surface facing the object side, and the lens closest to the image side has a convex surface facing the image side. The second lens group has negative refractive power, a 2-1 lens, and a 2-2 lens, and the 2-2 lens has a convex surface facing the image side. The third lens group has negative refractive power, the third lens group has a 3-1 lens, and the 3-1 lens is a meniscus lens having negative refractive power. The first, the second, and the third lens groups are arranged in order from the object side to the image side along the optical axis.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a lens assembly.

Background Art

[0002] Conventional long focal length lens assemblies usually have a long overall lens length, and as the focal length increases, the influence of vibration on image quality also increases. Therefore, it is necessary to have optical image stabilization to effectively eliminate vibration and improve image quality. Conventional long focal length lens assemblies usually do not have optical image stabilization and do not meet today's requirements. Thus, a new structure is needed for the lens assembly to meet the requirements of long focal length, miniaturization, high resolution, and optical image stabilization.

Summary of the Invention

Problems to be Solved by the Invention

[0003] To solve the above problems, an object of the present invention is to provide a lens assembly. The lens assembly of the present invention has the characteristics of a short overall lens length, high resolution, having optical image stabilization, and good optical performance.

Means for Solving the Problems

[0004] A lens assembly according to an exemplary embodiment of the present invention has a first lens group, a second lens group, and a third lens group. The first lens group has a positive refractive power, and the first lens group has at least four lenses, and these lenses are arranged in order from the object side to the image side along the optical axis. Among these lenses, the lens closest to the object side has a convex surface facing the object side, and the lens closest to the image side has a convex surface facing the image side. The second lens group has a negative refractive power, and the second lens group has a 2-1 lens and a 2-2 lens, and the 2-2 lens has a convex surface facing the image side. The third lens group has a negative refractive power, and the third lens group has a 3-1 lens, and the 3-1 lens is a meniscus lens having a negative refractive power. The first, second, and third lens groups are arranged in order from the object side to the image side along the optical axis. The 2-1 lens and the 2-2 lens are arranged in order from the object side to the image side along the optical axis.

[0005] The second lens group can move along a direction perpendicular to the optical axis to achieve optical hand shake correction, and the third lens group can move along the direction of the optical axis to perform focus adjustment.

[0006] Among the lenses of the first lens group, at least three lenses have a positive refractive power, and the refractive power of the 2-1 lens is opposite to the refractive power of the 2-2 lens. When the first lens group has two meniscus lenses, the second lens group has one meniscus lens.

[0007] The first lens group has a 1-1 lens, a 1-2 lens, a 1-3 lens, a 1-4 lens, and a 1-5 lens. The 1-1 lens, the 1-2 lens, the 1-3 lens, the 1-4 lens, and the 1-5 lens are arranged in order from the object side to the image side along the optical axis. The 1-4 lens has a negative refractive power, and the side surface shape of the object side of the 2-1 lens is different from the surface shape of the image side of the 1-3 lens. When the side surface shape of the object side of the 2-1 lens is a convex surface, the surface shape of the image side of the 1-3 lens is a concave surface. When the side surface shape of the object side of the 2-1 lens is a concave surface, the surface shape of the image side of the 1-3 lens is a convex surface.

[0008] The first lens group has a 1-1 lens, a 1-2 lens, a 1-3 lens, a 1-4 lens, and a 1-5 lens. The 3-1 lens has a convex surface facing the object side and a concave surface facing the image side. The 1-1 lens, the 1-2 lens, the 1-3 lens, the 1-4 lens, and the 1-5 lens are arranged in order from the object side to the image side along the optical axis.

[0009] The 1-3 lens has a positive refractive power. The 2-1 lens has a negative refractive power. When the 1-3 lens is a biconvex lens and has a convex surface facing the object side and another convex surface facing the image side, the 2-1 lens is a biconcave lens and has a concave surface facing the object side and another concave surface facing the image side. When the 1-3 lens is a meniscus lens, the 2-1 lens is also a meniscus lens.

[0010] When the 1-3 lens is a meniscus lens, the 1-3 lens has a convex surface facing the object side and a concave surface facing the image side. When the 2-1 lens is a meniscus lens, the 2-1 lens has a convex surface facing the object side and a concave surface facing the image side.

[0011] The 1-1 lens is a biconvex lens with a positive refractive power and has a convex surface facing the object side and another convex surface facing the image side. The 1-2 lens is a biconcave lens with a negative refractive power and has a concave surface facing the object side and another concave surface facing the image side. The 1-4 lens is a meniscus lens with a negative refractive power and has a convex surface facing the object side and a concave surface facing the image side. The 1-5 lens is a biconvex lens with a positive refractive power and has a convex surface facing the object side and another convex surface facing the image side. The 2-2 lens is a biconvex lens with a positive refractive power and further has a convex surface facing the object side.

[0012] The lens assembly of the present invention can further install a diaphragm between the first lens group and the second lens group.

[0013] The lens assembly satisfies at least one of the following conditions: 0.35 ≤ fG1 / f ≤ 0.45; -1.2 ≤ fG2 / f ≤ -0.85; -0.5 ≤ fG3 / f ≤ -0.4; Vd4 > Vd5; -0.92 ≤ (1-β)×βr ≤ -0.7; 2 ≤ f / BFL ≤ 4; 2.8 ≤ TTL / LG1L ≤ 3.9; where fG1 is the effective focal length of the first lens group, fG2 is the effective focal length of the second lens group, fG3 is the effective focal length of the third lens group, f is the effective focal length of the lens assembly, Vd4 is the Abbe number of lenses 1-4, Vd5 is the Abbe number of lenses 1-5, β is the magnification of the second lens group, βr is the magnification of the third lens group, BFL is the distance along the image-side optical axis from the image-side surface of lens 3-1, which is the closest to the image side in the third lens group, TTL is the distance along the image-side optical axis from the object-side surface of the lens closest to the object side in the first lens group, and LG1L is the distance between the optical axes of the image-side surface of the lens closest to the image side and the object-side surface of the lens closest to the object side in the first lens group.

[0014] To make the above objects, features, and advantages of the present invention more understandable, the following embodiments and the accompanying drawings will be referred to for a more detailed description.

Effects of the Invention

[0015] The lens assembly of the present invention has the characteristics of a short overall lens length, high resolution, having optical hand shake correction, and good optical performance.

Brief Description of the Drawings

[0016]

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DETAILED DESCRIPTION OF THE INVENTION

[0017] The present invention provides a lens assembly. The lens assembly of the first embodiment has a first lens group, a second lens group, and a third lens group. The first lens group has a positive refractive power and has at least four lenses. At least four lenses have a positive refractive power or a negative refractive power, but not all of them can be negative. At least four lenses are arranged along the optical axis from the object side to the image side. Among the at least four lenses, the lens closest to the object side has a convex surface facing the object side, ensures image quality, and has a concave surface, a convex surface, or a flat surface facing the image side. Among the at least four lenses, the lens closest to the image side has a convex surface facing the image side, ensures image quality, and has a concave surface, a convex surface, or a flat surface facing the object side. The remaining two of the four lenses are biconvex lenses, biconcave lenses, meniscus lenses, plano-convex lenses, or plano-concave lenses. The second lens group has a negative refractive power. The two lenses have a negative refractive index or a 2-1 lens and a 2-2 lens with a positive refractive index, but both of them cannot have a positive refractive power. The 2-2 lens has a convex surface facing the image side, ensures image quality, and has a concave surface, a convex surface, or a flat surface facing the object side. The 2-1 lens is a biconvex lens, a biconcave lens, a meniscus lens, a plano-convex lens, or a plano-concave lens. The third lens group has a negative refractive power. The third lens group has a 3-1 lens, and this 3-1 lens is a meniscus lens with a negative refractive power. The first lens group, the second lens group, and the third lens group are arranged in order from the object side to the image side along the optical axis. The above embodiments can achieve the basic functions.

[0018] The present invention provides a lens assembly of a second embodiment. The difference from the first embodiment is that the second lens group can move along a direction perpendicular to the optical axis to perform optical hand-shake correction, and since the second lens group has two lenses, good image quality can be maintained during shake prevention. The third lens group can move along the direction of the optical axis to perform focus adjustment, and since the third lens group has a negative refractive power, the total lens length is decreased during focus adjustment.

[0019] The present invention provides a lens assembly of a third embodiment. The difference from the second embodiment is that the first lens group has at least three lenses with positive refractive power and one lens with negative refractive power. The refractive power of the 2-1 lens is opposite to that of the 2-2 lens. When the first lens group has two meniscus lenses, the second lens group has a meniscus lens.

[0020] The present invention provides a lens assembly of a fourth embodiment. The difference from the first embodiment is that the first lens group has lenses 1-1, 1-2, 1-3, 1-4, and 1-5, and the surface shape of the image side surface of the 1-3 lens is different from the side surface shape of the object side surface of the 2-1 lens. When the surface shape of the object side surface of the 2-1 lens is convex, the surface shape of the image side surface of the 1-3 lens is concave, and when the surface shape of the object side surface of the 2-1 lens is concave, the surface shape of the image side surface of the 1-3 lens is convex.

[0021] The present invention provides a lens assembly of a fifth embodiment. Referring to Table 1, Table 2, Table 4, Table 5, Table 7, and Table 8, Table 1, Table 4, and Table 7 are correlation parameter tables of each lens of the preferred first, second, and third embodiments of the present invention, respectively, and Table 2, Table 5, and Table 8 are correlation parameter tables of the aspherical surfaces of the aspherical lenses in Table 1, Table 4, and Table 7, respectively.

[0022] FIG. 1, FIG. 7, and FIG. 13 are diagrams showing the lens arrangements and optical paths of the lens assemblies of the first, second, and third preferred embodiments of the present invention, respectively. The lens assembly 1 has a first lens group LG11, a diaphragm ST1, a second lens group LG12, and a third lens group LG13, and the first lens group LG11, the diaphragm ST1, the second lens group LG12, and the third lens group LG13 are arranged in order from the object side to the image side along the optical axis OA1. The first lens group LG11 has a positive refractive power and includes a 1-1 lens L11, a 1-2 lens L12, a 1-3 lens L13, a 1-4 lens L14, and a 1-5 lens L15. The second lens group LG12 has a negative refractive power and includes a 2-1 lens L16 and a 2-2 lens L17. The third lens group LG13 has a negative refractive power and includes a 3-1 lens L18. The lens assembly 2 has a first lens group LG21, a diaphragm ST2, a second lens group LG22, and a third lens group LG23, and the first lens group LG21, the diaphragm ST2, the second lens group LG22, and the third lens group LG23 are arranged in order from the object side to the image side along the optical axis OA2. The first lens group LG21 has a positive refractive power and includes a 1-1 lens L21, a 1-2 lens L22, a 1-3 lens L23, a 1-4 lens L24, and a 1-5 lens L25. The second lens group LG22 has a negative refractive power and includes a 2-1 lens L26 and a 2-2 lens L27. The third lens group LG23 has a negative refractive power and includes a 3-1 lens L28. The lens assembly 3 has a first lens group LG31, a diaphragm ST3, a second lens group LG32, and a third lens group LG33, and the first lens group LG31, the diaphragm ST3, the second lens group LG32, and the third lens group LG33 are arranged in order from the object side to the image side along the optical axis OA3. The first lens group LG31 has a positive refractive power and includes a 1-1 lens L31, a 1-2 lens L32, a 1-3 lens L33, a 1-4 lens L34, and a 1-5 lens L35. The second lens group LG32 has a negative refractive power and includes a 2-1 lens L36 and a 2-2 lens L37. The third lens group LG33 has a negative refractive power and includes a 3-1 lens L38.

[0023] 1-1 Lenses L11, L21, and L31 are biconvex lenses with positive refractive power, formed of glass material. Their object sides S11, S21, S31, and image sides S12, S22, S32 are all convex and all spherical surfaces. 1-2 Lenses L12, L22, and L32 are biconcave lenses with negative refractive power, formed of glass material. Their object sides S12, S22, S32, and image sides S13, S23, S33 are all concave and all spherical surfaces. 1-3 Lenses L13, L23, and L33 have positive refractive power and are formed of glass material. Their object sides S14, S24, S34 are convex, and their object sides S14, S24, S34 and image sides S15, S25, S35 are all spherical surfaces. 1-4 Lenses L14, L24, and L34 are meniscus lenses with negative refractive power. Their object sides S16, S26, S36 are convex, their image sides S17, S27, S37 are concave, their object sides S16, S26, S36 are aspherical surfaces, and their image sides S17, S27, S37 are spherical surfaces. 1-5 Lenses L15, L25, and L35 are biconvex lenses with positive refractive power, formed of plastic material. Their object sides S18, S28, S38 and image sides S19, S29, S39 are convex. Their object sides S18, S28, S38 are aspherical surfaces, and their image sides S19, S29, S39 are spherical surfaces. 2-1 Lenses L16, L26, l36 have negative refractive power and are formed of plastic material. Their image sides S112, S212, S312 are concave, their object sides S111, S211, S311 are aspherical surfaces, and their image sides S112, S212, S312 are spherical surfaces. 2-2 Lenses L17, L27, and L37 are biconvex lenses with positive refractive power, formed of plastic material. Their object sides S113, S213, S313 are convex and aspherical surfaces, and their image sides S114, S214, S314 are convex and spherical surfaces. 3-1 Lenses L18, L28, and L38 are meniscus lenses with negative refractive power. Their object sides S115, S215, S315 are convex, their image sides S116, S216, S316 are concave, and both their object sides S115, S215, S315 and image sides S116, S216, S316 are spherical surfaces.The lenses L11, L21, L31 of 1-1 and the lenses L12, L22, L32 of 1-2 are fixed with cement, or there is no air gap between the two lenses. In other embodiments, the lens fixed with cement may be a single lens having a positive refractive power. The second lens group LG12 can move along the direction perpendicular to the optical axis OA1 to perform optical hand shake correction, and the lenses of the second lens group LG12 are formed of a plastic material, thereby reducing the weight and increasing the reaction speed. The third lens group LG13 moves along the direction of the optical axis OA1 for focusing. The surface shape of the object side of the 1-1 lens and the surface shape of the image side of the 1-5 lens can effectively ensure the image quality. The surface shape of the image side of the 1-1 lens can effectively improve the chromatic aberration. The surface shape of the object side of the 2-1 lens and the surface shape of the image side of the 2-2 lens can effectively ensure the anti-shake function. The surface shape of the image side of the 1-3 lens is different from the surface shape of the object side of the 2-1 lens and can effectively ensure the image quality.

[0024] The above design can effectively shorten the total lens length, effectively increase the resolution, and effectively correct the chromatic aberration, aberration, and anti-shake function. In addition, the lens assembly can optimize the above functions by satisfying at least one of the following conditions:

[0025] 0.35 ≦ fG1 / f ≦ 0.45; (1)

[0026] -1.2 ≦ fG2 / f ≦ -0.85; (2)

[0027] -0.5 ≦ fG3 / f ≦ -0.4; (3)

[0028] Vd4>Vd5; (4)

[0029] -0.92 ≦ (1-β)×βr ≦ -0.7; (5)

[0030] 2 ≦ f / BFL ≦ 4; (6)

[0031] 2.8 ≦ TTL / LG1L ≦ 3.9; (7)

[0032] In the formula, fG1 is the effective focal length of the first lens group, for example, in the preferred first to third embodiments, the effective focal lengths of the first lens groups LG11, LG21, LG31; fG2 is the effective focal length of the second lens group, for example, in the preferred first to third embodiments, the effective focal lengths of the second lens groups LG12, LG22, LG32; fG3 is the effective focal length of the third lens group, for example, in the preferred first to third embodiments, the effective focal lengths of the third lens groups LG13, LG23, LG33; f is the effective focal length of the lens assembly, for example, in the preferred first to third embodiments, the effective focal lengths of the lens assemblies 1, 2, 3; Vd4 is the Abbe number of the 1-4 lenses, for example, in the preferred first to third embodiments, the Abbe numbers of the 1-4 lenses L14, L24, L34; Vd5 is the Abbe number of the 1-5 lenses, for example, in the preferred first to third embodiments, the Abbe numbers of the 1-5 lenses L15, L25, L35; β is the magnification of the second lens group, for example, in the preferred first to third embodiments, the magnifications of the second lens groups LG12, LG22, LG32; βr is the magnification of the third lens group, for example, in the preferred first to third embodiments, the magnifications of the third lens groups LG13, LG23, LG33; BFL is the interval along the optical axis from the image side surface of the 3-1 lens to the image side, for example, in the preferred first to third embodiments, the intervals along the optical axes OA1, OA2, OA3 of the image sides IMA1, IMA2, IMA3 from the image side surfaces S116, S216, S316 of the 3-1 lenses L18, L28, L38 closest to the image side in the third lens groups LG13, LG23, LG33; TTL is the interval along the optical axis from the object side surface of the 1-1 lens to the image side, for example, in the preferred first to third embodiments, the intervals along the optical axes OA1, OA2, OA3 of the image sides IMA1, IMA2, IMA3 from the object side surfaces S11, S21, S31 of the 1-1 lenses L11, L21, L31 closest to the object side in the first lens groups LG11, LG21, LG31; LG1L is the interval along the optical axis from the object side surface of the 1-1 lens to the image side surface of the 1-5 lens, for example, in the preferred first to third embodiments, the intervals between the optical axes OA1, OA2, OA3 of the image side surfaces S19, S29, S39 of the 1-5 lenses L15, L25, L35 closest to the image side in the first lens groups LG11, LG21, LG31 from the object side surfaces S11, S21, S31 of the 1-1 lenses L11, L21, L31 closest to the object side in the first lens groups LG11, LG21, LG31.The above magnification refers to the value obtained by dividing Tan(θ1) of the incident beam angle by Tan(θ2) of the output beam angle, where θ1 is the incident beam angle and θ2 is the output beam angle. Taking the magnification of the second lens group as an example, the measurement method of Tan(θ1) is as follows: Let the collimated light pass through the lens group in front of the second lens group, and on the other side of the lens group relative to the collimated light, install a light shielding plate (or aperture stop) with a radius of a predetermined length. Then, measure the distance from the focus after the light passes through the light shielding plate to the light shielding plate. Tan(θ1) is equal to the radius of the light shielding plate divided by the distance from the focus to the light shielding plate. The measurement method of Tan(θ2) is the same as the above, except that the light shielding plate is installed on the other side of the second lens group relative to the collimated light. That is, the collimated light first passes through the lens group in front of the second lens group, then passes through the second lens group and the light shielding plate, and measures the distance from the focus to the light shielding plate. Tan(θ2) is equal to the radius of the light shielding plate divided by the distance from the focus to the light shielding plate.

[0033] Condition (1): When 0.35 ≦ fG1 / f ≦ 0.45 is satisfied, the lens assembly effectively achieves the purpose of miniaturization. Condition (2): When -1.2 ≦ fG2 / f ≦ -0.85 is satisfied, the movement amount of the anti-shake lens group is effectively and accurately controlled. Condition (3): When -0.5 ≦ fG3 / f ≦ -0.4 is satisfied, the movement of the focus lens group is effectively and accurately controlled. Condition (4): When Vd4 > Vd5 is satisfied, the chromatic aberration is effectively reduced. Condition (5): When -0.92 ≦ (1-β)×βr ≦ -0.7 is satisfied, the optical anti-shake correction is effectively improved. Condition (6): When 2 ≦ f / BFL ≦ 4 is satisfied, the ghost image is effectively reduced. Condition (7): When 2.8 ≦ TTL / LG1L ≦ 3.9 is satisfied, the total lens length is effectively shortened.

[0034] A detailed description of the lens assembly according to a preferred first embodiment of the present invention is as follows. Referring to FIG. 1, the lens assembly 1 includes a first lens group LG11, a diaphragm ST1, a second lens group LG12, and a third lens group LG13. The first lens group LG11, the diaphragm ST1, the second lens group LG12, and the third lens group LG13 are arranged in order from the object side to the image side along the optical axis OA1. The first lens group LG11 includes a 1-1 lens L11, a 1-2 lens L12, a 1-3 lens L13, a 1-4 lens L14, and a 1-5 lens L15. The 1-1 lens L11, the 1-2 lens L12, the 1-3 lens L13, the 1-4 lens L14, and the 1-5 lens L15 are arranged in order from the object side to the image side along the optical axis OA1. The second lens group LG12 includes a 2-1 lens L16 and a 2-2 lens L17. The 2-1 lens L16 and the 2-2 lens L17 are arranged in order from the object side to the image side along the optical axis OA1. The third lens group LG13 includes a 3-1 lens L18. During operation, the light rays from the object side are finally imaged on the image plane IMA1.

[0035] According to the fifth to eighth paragraphs in the embodiment: the 1-3 lens L13 is a biconvex lens, and its image-side surface S15 is a convex surface; the 1-4 lens L14 is formed of a plastic material; the 2-1 lens L16 is a biconcave lens, and its object-side surface S111 is a concave surface; the 3-1 lens L18 is formed of a glass material. With the above-described lens design, the lens assembly 1 can effectively shorten the total lens length, effectively increase the resolution, effectively correct the aberration, and effectively correct the chromatic aberration. Table 1 is a correlation parameter table of each lens of the lens assembly 1 in FIG. 1.

[0036]

Table 1

[0037] The concavity z of the aspherical surface of each aspherical lens in Table 1 is calculated by the following formula: z = ch 2 / {1+[1-(k+1)c 2 h2 1 / 2}+Ah 2 +Bh 4 +Ch 6 +Dh 8

[0038] c is the curvature, h is the perpendicular distance from the lens surface to the axis, k is the conic constant, and A, B, C, and D are the aspherical coefficients.

[0039] Table 2 is a correlation parameter table of the aspherical surfaces of each aspherical lens in Table 1, where k is the conic constant, and A, B, C, and D are the aspherical coefficients.

[0040]

Table 2

[0041] Table 3 shows the correlation parameter values of the lens assembly 1 of the preferred first embodiment and its corresponding conditions (1)-(7).

[0042]

Table 3

[0043] In addition, the optical performance of the lens assembly 1 of the preferred first embodiment meets the requirements. As can be seen from Figure 2, the longitudinal aberration is in the range of -0.02 mm to 0.03 mm. As can be seen from Figure 3, the field curvature is in the range of -0.04 mm to 0.03 mm. As can be seen from Figure 4, the distortion is 0% to 1.5%. As can be seen from Figure 5, the lateral color is in the range of -1 μm to 0 μm. As can be seen from Figure 6, the transverse aberration is in the range of -8 μm to 8 μm. It can be seen that the longitudinal aberration, field curvature, distortion, lateral color, and transverse aberration of the lens assembly 1 of the preferred first embodiment are effectively corrected, and good optical performance can be obtained.

[0044] ​A detailed description of the lens assembly according to a preferred second embodiment of the present invention is as follows. Referring to FIG. 7, the lens assembly 2 includes a first lens group LG21, an aperture ST2, a second lens group LG22, and a third lens group LG23. The first lens group LG21, the aperture ST2, the second lens group LG22, and the third lens group LG23 are arranged in order from the object side to the image side along the optical axis OA2. The first lens group LG21 includes a 1-1 lens L21, a 1-2 lens L22, a 1-3 lens L23, a 1-4 lens L24, and a 1-5 lens L25, and the 1-1 lens L21, the 1-2 lens L22, the 1-3 lens L23, the 1-4 lens L24, and the 1-5 lens L25 are arranged in order from the object side to the image side along the optical axis OA2. The second lens group LG22 includes a 2-1 lens L26 and a 2-2 lens L27, and the 2-1 lens L26 and the 2-2 lens L27 are arranged in order from the object side to the image side along the optical axis OA2. The third lens group LG23 includes a 3-1 lens L28. During operation, light rays from the object side are finally imaged on the image plane IMA2.

[0045] According to the fifth to eighth paragraphs in the embodiment: the 1-3 lens L23 is a meniscus lens, and the image-side surface S25 is concave; the 1-4 lens L24 is formed of a glass material; the 2-1 lens L26 is a meniscus lens, and the object-side surface S211 is convex; the 3-1 lens L28 is formed of a plastic material. With the above-described lens design, the lens assembly 2 can effectively shorten the total lens length, effectively increase the resolution, effectively correct the aberration, and effectively correct the chromatic aberration. Table 4 is a correlation parameter table for each lens of the lens assembly 2 in FIG. 7.

[0046]

Table 4

[0047] In Table 4, the definition of the concavity z of the aspherical surface of the aspherical lens is the same as that in Table 1, so it will not be described in detail here. Table 5 is a correlation parameter table for the aspherical surface of the aspherical lens in Table 4.

[0048]

Table 5

[0049] Table 6 shows the correlation parameter values of the lens assembly 2 of the preferred second embodiment and the calculated values of the corresponding conditions (1)-(7).

[0050]

Table 6

[0051] In addition, the optical performance of the lens assembly 2 of the preferred second embodiment meets the requirements. As can be seen from FIG. 8, the longitudinal aberration is in the range of -0.01 mm to 0.04 mm. As can be seen from FIG. 9, the field curvature is in the range of -0.03 mm to 0.04 mm. As can be seen from FIG. 10, the distortion is 0% to 1.5%. As can be seen from FIG. 11, the lateral color is in the range of -1 μm to 0 μm. As can be seen from FIG. 12, the transverse aberration is -8 μm to 8 μm. It can be seen that the longitudinal aberration, field curvature, distortion, lateral color, and transverse aberration of the lens assembly 2 of the preferred second embodiment are effectively corrected, and good optical performance can be obtained.

[0052] A detailed description of the lens assembly according to a preferred third embodiment of the present invention is as follows. Referring to FIG. 13, the lens assembly 3 has a first lens group LG31, a diaphragm ST3, a second lens group LG32, and a third lens group LG33. The first lens group LG31, the diaphragm ST3, the second lens group LG32, and the third lens group LG33 are arranged in order from the object side to the image side along the optical axis OA3. The first lens group LG31 has a 1-1 lens L31, a 1-2 lens L32, a 1-3 lens L33, a 1-4 lens L34, and a 1-5 lens L35. The 1-1 lens L31, the 1-2 lens L32, the 1-3 lens L33, the 1-4 lens L34, and the 1-5 lens L35 are arranged in order from the object side to the image side along the optical axis OA3. The second lens group LG32 has a 2-1 lens L36 and a 2-2 lens L37. The 2-1 lens L36 and the 2-2 lens L37 are arranged from the object side to the image side along the optical axis OA3. The third lens group LG33 has a 3-1 lens L38. During operation, the light rays from the object side are finally imaged on the image plane IMA3.

[0053] According to the fifth to eighth paragraphs in the embodiment: the 1-3 lens L33 is a meniscus lens, and its image-side surface S35 is concave; the 1-4 lens L34 is formed of a plastic material; the 2-1 lens L36 is a meniscus lens, and its object-side surface S311 is convex; the 3-1 lens L38 is formed of a glass material. With the above-described lens design, the lens assembly 3 can effectively shorten the total lens length, effectively increase the resolution, effectively correct the aberration, and effectively correct the chromatic aberration. Table 7 is a correlation parameter table of each lens of the lens assembly 3 in FIG. 13.

[0054]

Table 7

[0055] In Table 7, the definition of the concavity z of the aspherical surface of the aspherical lens is the same as that in Table 1, so it will not be described in detail here. Table 8 is a correlation parameter table of the aspherical surface of the aspherical lens in Table 7.

[0056]

Table 8

[0057] Table 9 shows the correlation parameter values of the lens assembly 3 of the preferred third embodiment and the calculated values of the corresponding conditions (1)-(7).

[0058]

Table 9

[0059] In addition, the optical characteristics of the lens assembly 3 of the preferred third embodiment also meet the requirements. As can be seen from FIG. 14, the longitudinal aberration is in the range of -0.01 mm to 0.03 mm. As can be seen from FIG. 15, the field curvature is in the range of -0.02 mm to 0.03 mm. As can be seen from FIG. 16, the distortion is in the range of 0% to 1.5%. As can be seen from FIG. 17, the lateral color is in the range of -1 μm to 0 μm. As can be seen from FIG. 18, the transverse aberration is in the range of -8 μm to 8 μm. It can be understood that the longitudinal aberration, field curvature, distortion, lateral color, and transverse aberration of the lens assembly of the preferred third embodiment are effectively corrected, and good optical performance can be obtained.

[0060] The lens materials in all the above embodiments are preferable for achieving all the above effects.

[0061] In the present invention, the preferred embodiments have been disclosed as described above, but these are by no means intended to limit the present invention. Any person skilled in the art can make various modifications without departing from the spirit of the present invention.

Explanation of Signs

[0062] 1, 2, 3... lens assemblies LG11, LG21, LG31... first lens group LG12, LG22, LG32... second lens group LG13, LG23, LG33... The third lens group IMA1, IMA2, IMA3... Image plane OA1, OA2, OA3... Optical axis L11, L21, L31... 1-1 lens L12, L22, L32... 1-2 lens L13, L23, L33... 1-3 lens L14, L24, L34... 1-4 lens L15, L25, L35... 1-5 lens L16, L26, L36... 2-1 lens L17, L27, L37... 2-2 lens L18, L28, L38... 3-1 lens ST1, ST2, ST3... Diaphragm S11, S21, S31... Object side of 1-1 lens S12, S22, S32... Object side of 1-2 lens S14, S24, S34... Object side of 1-3 lens S16, S26, S36... Object side of 1-4 lens S18, S28, S38... Object side of 1-5 lens S111, S211, S311... Object side of 2-1 lens S113, S213, S313... Object side of 2-2 lens S115, S215, S315... Object side of 3-1 lens S12, S22, S32... Image side of 1-1 lens S13, S23, S33... Image side of 1-2 lens S15, S25, S35... Image side of 1-3 lens S17, S27, S37... Image side of 1-4 lens S19, S29, S39... Image side of 1-5 lens S112, S212, S312... Image side of 2-1 lens S114, S214, S314... Image side of 2-2 lens S116, S216, S316... Image side of 3-2 lens S110, S210, S310... Diaphragm plane

Claims

1. A lens assembly, having a positive refractive power and composed of five lenses, the lenses being arranged in order from the object side to the image side along the optical axis, the lens closest to the object side among the lenses having a positive refractive power and having a convex surface facing the object side, the lens closest to the image side having a positive refractive power and having a convex surface facing the image side, the second closest lens to the image side having a negative refractive power, and the third closest lens to the image side having a positive refractive power, a first lens group; having a negative refractive power and composed of a 2-1 lens and a 2-2 lens, the 2-1 lens having a negative refractive power, the 2-2 lens having a positive refractive power and having a convex surface facing the image side, a second lens group, and having a negative refractive power and composed of a 3-1 lens, the 3-1 lens being a meniscus lens having a negative refractive power, a third lens group, wherein the first lens group, the second lens group, and the third lens group are arranged in order from the object side to the image side along the optical axis, wherein the 2-1 lens and the 2-2 lens are arranged in order from the object side to the image side along the optical axis, wherein the first lens group is composed of a 1-1 lens, a 1-2 lens, a 1-3 lens, a 1-4 lens, and a 1-5 lens, wherein the 1-1 lens has a positive refractive power, the 1-2 lens has a negative refractive power, the 1-3 lens has a positive refractive power, the 1-4 lens has a negative refractive power, and the 1-5 lens has a positive refractive power, wherein the 3-1 lens has a convex surface facing the object side and a concave surface facing the image side, wherein the 1-1 lens, the 1-2 lens, the 1-3 lens, the 1-4 lens, and the 1-5 lens are arranged in order from the object side to the image side along the optical axis. A lens assembly characterized by this.

2. The second lens group is movable along a direction perpendicular to the optical axis, and The third lens group is movable along the direction of the optical axis. The lens assembly according to Claim 1, characterized by this.

3. The side shape of the object side surface of the 2-1 lens is different from the surface shape of the image side surface of the 1-3 lens. When the surface shape of the object side surface of the 2-1 lens is convex, the surface shape of the image side surface of the 1-3 lens is concave. When the surface shape of the object side surface of the 2-1 lens is concave, the surface shape of the image side surface of the 1-3 lens is convex. The lens assembly according to claim 1, characterized in that.

4. The 1-1 lens is a biconvex lens and has a convex surface facing the object side and another convex surface facing the image side. The 1-2 lens is a biconcave lens and has a concave surface facing the object side and another concave surface facing the image side. The 1-4 lens is a meniscus lens and has a convex surface facing the object side and a concave surface facing the image side. The 1-5 lens is a biconvex lens and has a convex surface facing the object side and another convex surface facing the image side. The 2-2 lens is a biconvex lens having a positive refractive power and further has another convex surface facing the object side. The lens assembly according to claim 1, characterized in that.

5. The lens assembly satisfies at least one of the following conditions: 0.35 ≤ fG1 / f ≤ 0.45; -0.5 ≤ fG3 / f ≤ -0.4; Vd4 > Vd5; －０．９２ ≦ (１-β)×βr ≦ －０．７; 2 ≤ f / BFL ≤ 4; 2.8 ≤ TTL / LG1L ≤ 3.9; Wherein, the fG1 is the effective focal length of the first lens group, the fG3 is the effective focal length of the third lens group, the f is the effective focal length of the lens assembly, the Vd4 is the Abbe number of the 1-4 lens, the Vd5 is the Abbe number of the 1-5 lens, the β is the magnification of the second lens group, the βr is the magnification of the third lens group, the BFL is the interval along the optical axis on the image side from the image side surface of the lens closest to the image side in the third lens group, the TTL is the interval along the optical axis on the image side from the object side surface of the lens closest to the object side in the first lens group, and the LG1L is the interval along the optical axis of the image side surface of the lens closest to the image side in the first lens group from the object side surface of the lens closest to the object side in the first lens group. The lens assembly according to claim 1, characterized in that.

6. When the first lens group has two meniscus lenses, the second lens group has one meniscus lens, when the 1-3 lens is a biconvex lens and has a convex surface facing the object side and another convex surface facing the image side, the 2-1 lens is a biconcave lens and has a concave surface facing the object side and another concave surface facing the image side, when the 1-3 lens is a meniscus lens, the 2-1 lens is also a meniscus lens, when the 1-3 lens is a meniscus lens, the 1-3 lens has a convex surface facing the object side and a concave surface facing the image side, when the 2-1 lens is a meniscus lens, the 2-1 lens has a convex surface facing the object side and a concave surface facing the image side, furthermore, it has a diaphragm installed between the first lens group and the second lens group, and the lens assembly satisfies the following conditions: -1.2 ≤ fG2 / f ≤ -0.85; wherein, the fG2 is the effective focal length of the second lens group, and the f is the effective focal length of the lens assembly. The lens assembly according to any one of claims 1 to 5, characterized in that.

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