TWI420141B - Zoom lens - Google Patents

Description

Zoom lens

The invention relates to a zoom lens, in particular to a photographic lens suitable for small digital image products and having high zoom magnification and high resolution.

In recent years, with the rapid integration of optical technologies such as photography and photography and digital electronic technology, new products such as camera phones, compact digital cameras and small home cameras are oriented toward miniaturization and light weight, and must meet high zoom magnification and high resolution. Requirements. The purpose of the high-magnification zoom lens is to improve the convenience of shooting, avoid the ashing caused by frequent lens changes, and reduce the cost of input. However, high zoom magnification lenses are achieved with multiple lens sets, multiple lenses, and a longer lens length version, so they are larger. Moreover, the optical characteristics of the high-power zoom lens usually lead to a reduction in the quality of the shot, so special low-dispersion lenses and aspherical lenses are required to achieve the resolution requirements.

In the high-magnification zoom lens, in order to obtain a desired zoom ratio and obtain excellent optical characteristics over the entire zoom range, it is necessary to appropriately set the lens configuration of each lens combination. In the zoom lens, if the power of the lens combination is increased, the amount of movement of each lens combination at the time of zooming is reduced, and the entire lens length may be shortened. However, if only the power of each lens combination is enhanced, the aberration variation becomes larger as the zoom is increased, and the aberration is difficult to be corrected. Therefore, in order to realize a small lens system having a high zoom ratio and a small number of lenses, it is necessary to appropriately set the movement conditions of the respective lens combinations accompanying the zoom, the power of each lens combination, and the like. If these are not satisfied, the occurrence of various aberrations will increase, and it is difficult to obtain good image quality over the entire zoom range.

Please refer to the disclosure of CN 100338495C, the zoom lens is composed of five groups of lens groups, and the diopter of the five groups of lenses is positive, negative, positive, positive and positive from the object side in the wide angle. When the end is changed to the telephoto end, the first lens group, the third lens group, and the fourth lens group are both moved toward the object side, the fifth lens group is also moved toward the object side, and the second lens group is moved toward the image. Side, thereby increasing the interval between the first lens group and the second lens group, decreasing the interval between the second lens group and the third lens group, and changing the interval between the third lens group and the fourth lens group The interval between the fourth lens group and the fifth lens group is increased. However, the zoom lens does not obtain a sufficiently large zoom ratio, and if a high zoom ratio is obtained, an aberration that is difficult to sufficiently correct is inevitably generated.

Therefore, it is necessary to provide a small zoom lens with high zoom magnification and high resolution.

A main object of the present invention is to provide a zoom lens having a high zoom magnification and a high resolution, and the zoom lens can achieve a miniaturization of the structure.

According to the above object of the present invention, the present invention provides a zoom lens including, in order from the object side to the image side, a first lens group having positive refracting power, a second lens group having negative refracting power, and a third lens having positive refracting power. a lens group; a fourth lens group having a negative refracting power; and a fifth lens group having a positive refracting power. When the zoom lens is zoomed from the wide-angle end to the telephoto end, the first lens group and the third lens group both move toward the object side, and the second lens group and the fifth lens group both move toward the image side; When the object distance needs to be adjusted, the fourth lens group moves toward the image side.

The zoom lens satisfies the following conditional formula:

Wherein MG1 is the amount of movement of the first lens group from the wide-angle end to the telephoto end during zooming; fW is the focal length of the zoom lens at the wide-angle end; fT is the focal length of the zoom lens at the telephoto end; Y is the imaging surface The maximum diagonal length of the MG2 is the amount of movement of the second lens group from the wide-angle end to the telephoto end during zooming; fG2 is the focal length of the second lens group; MG3 is the third lens group from the wide-angle end to the zoom lens The amount of movement at the telephoto end; and fG3 is the focal length of the third lens group.

Compared with the prior art of the present invention, the zoom ratio of the zoom lens of the present invention can be up to 15X to 20X, and the optical system can make the second lens group G2, the third lens group G3 and the fourth lens group G4 of the zoom lens The diameter is reduced, thereby reducing the storage space and shortening the storage length. Therefore, the zoom lens of the present invention has high zoom magnification and high resolution characteristics, and can achieve a compact structure.

Referring to the first figure, the zoom lens 1 of the present invention is sequentially from the object side to the image side: a first lens group G1 having positive refracting power; a second lens group G2 having negative refracting power; an aperture S; A third lens group G3 of positive refractive power; a fourth lens group G4 having negative refractive power; a fifth lens group G5 having positive refractive power; a glass plate GP; and an imaging surface IP. When the zoom lens 1 is zoomed from the wide-angle end to the telephoto end, the first lens group G1 and the third lens group G3 are both moved toward the object side, and the second lens group G2 and the fifth lens group G5 are both oriented toward the image. The side moves. When the object distance change requires focusing, the fourth lens group G4 moves toward the image side. It can be seen that when the zoom lens 1 changes from the wide-angle end to the telephoto end, the interval between the first lens group G1 and the second lens group G2 becomes larger, and the second lens group G2 and the third lens group G3 The interval between the third lens group G3 and the fourth lens group G4 becomes larger, and the interval between the fourth lens group G4 and the fifth lens group G5 becomes larger.

The zoom lens 1 satisfies the following conditional formula:

Wherein MG1 is the amount of movement of the first lens group G1 from the wide-angle end to the telephoto end when zooming; fW is the focal length of the zoom lens 1 at the wide-angle end; fT is the focal distance of the zoom lens 1 at the telephoto end; The maximum diagonal length of the imaging surface; MG2 is the amount of movement of the second lens group G2 from the wide-angle end to the telephoto end during zooming; fG2 is the focal length of the second lens group G2; MG3 is the third lens group G3 The amount of movement from the wide-angle end to the telephoto end at the time of zooming; and fG3 is the focal length of the third lens group G3.

According to the above design conditions, the zoom ratio of the zoom lens 1 of the present invention can be up to 15X to 20X, and the optical system can change the outer diameters of the second lens group G2, the third lens group G3, and the fourth lens group G4 of the zoom lens 1 Small, thereby reducing the storage space and achieving the goal of miniaturization of the zoom lens 1.

Referring to the first figure, the first lens group G1 of the zoom lens 1 of the present invention includes a crescent-shaped negative lens 11 along the optical axis 100 from the object side, having a convex surface 101 and a concave surface 102; A crescent-shaped convex lens 12 having two convex surfaces 103, 104; and a crescent-shaped convex lens 13 having a convex surface 105 and a concave surface 106.

The second lens group G2 includes, in order from the object side along the optical axis 100, a crescent-shaped negative lens 14 having a convex surface 107 and a concave surface 108; and a set of lenticular lenses 15 joined to a double concave lens 16 The lens group, wherein the lenticular lens 15 has two convex surfaces 109, 110, the double concave lens 16 has two concave surfaces 110', 111; and a crescent-shaped negative lens 17. The second lens group G2 includes at least one aspherical surface. For example, both surfaces 112, 113 of the crescent-type negative lens 17 are aspherical.

The third lens group G3 includes, in order from the object side along the optical axis 100, a convex lens 18 having a convex surface 114 and a concave surface 115, and at least one surface is aspherical, for example, the convex surface 114 is aspherical; a lens group formed by bonding a concave lens 19 and a lenticular lens 20, wherein the concave lens 19 has two concave surfaces 116, 117 having two convex surfaces 117', 118; and a convex lens 21 having a convex surface 119 and a concave surface 120. The convex lens 21 has an aspherical surface, for example, the concave surface 120 is aspherical. During the zooming process, the third lens group G3 can also be used as a correction system for correcting the curvature of field of each focus point.

The aperture S is disposed on the object side of the third lens group G3, and the aperture S is moved together with the third lens group G3 during zooming.

The fourth lens group G4 is formed by joining two spherical lenses. The optical axis 100 includes, in order from the object side, a convex lens 22 having a concave surface 121 and a convex surface 122, and a double concave lens 23 having two Concave surfaces 122', 123. The fourth lens group G4 is used for focusing when different shooting distances are used.

The fifth lens group G5 includes, in order from the object side along the optical axis 100, a convex lens 24 having two convex surfaces 124, 125, and a concave lens 25 having a concave surface 126 and a convex surface 127. The convex surface 124 of the convex lens 24 is aspherical.

The glass plate GP has two surfaces 128, 129 which are coated with a film having a certain effect (for example, anti-reflection or infrared filtering) on at least one surface 128 or 129 to improve image quality.

The first numerical implementation of the zoom lens 1 of the present invention is shown in Table 1, Table 2, and Table 3 below. In the first numerical embodiment shown in Tables 1 to 3, all moment values (radius of curvature and thickness) are in millimeters. In addition, the two columns "type" and "curvature radius" in Table 1 refer to the type of the corresponding lens surface (that is, whether it is a "non-curved surface" or "standard" type surface) and the radius of curvature; the "thickness" column It refers to the thickness of the lens measured along the optical axis, or the distance between two adjacent lenses along the optical axis 100, that is, the image side surface (surface 102) of the previous lens (for example, the crescent-shaped negative lens 11) The distance from the object side surface (surface 103) of the latter lens (for example, the crescent lens 12) along the optical axis 100, in order to simplify the table, in Table 1, both (ie thickness and distance) It is to be understood that the term "thickness" is used for the purpose of simplification and is not intended to be an additional limitation or a misunderstanding of the invention. In Tables 1 and 3, D6 refers to the interval between the first lens group G1 and the second lens group G2, D13 refers to the interval between the second lens group G2 and the third lens group G3, and D21 refers to the The interval between the three lens group G3 and the fourth lens group G4, and D24 refers to the interval between the fourth lens group G4 and the fifth lens group G5.

The zoom lens 1 of the present invention adopts an aspherical design. For example, both surfaces 112 and 113 of the crescent-shaped negative lens 17 of the second lens group G2 are aspherical; the convex surface 114 of the convex lens 18 of the third lens group G3 is non-spherical. The spherical surface; the concave surface of the convex lens 21 of the third lens group G3 is aspherical; and the convex surface 124 of the convex lens 24 of the fifth lens group G5 is aspherical. The aspheric design formula is expressed as follows: Where: z is the displacement value of the surface apex as the reference distance from the optical axis along the optical axis direction; k is the taper constant (Conic Constant); c=1/r, r is the radius of curvature; h is the lens height E ₄ represents four aspheric coefficients; E ₆ represents six aspheric coefficients; E ₈ represents eight aspheric coefficients; E ₁₀ represents ten aspheric coefficients; E ₁₂ represents twelve aspheric surfaces; Coefficient; E ₁₄ represents fourteen aspheric coefficients; and E ₁₆ represents sixteen aspheric coefficients.

In the first numerical embodiment, the specific values of the aspheric coefficients are as shown in Table 2 below:

According to the first numerical embodiment described above, the parameters of the zoom lens 1 of the present invention are as follows:

According to the above numerical calculation, it can be concluded that the value of the conditional expression (1) is 0.69, the value of the conditional expression (2) is 1.15, and the value of the conditional expression (3) is 6.48.

Please refer to the aberration diagrams of the zoom lens 1 of the present invention at the telephoto end shown in FIGS. 2A to 2E, and the aberration curves of the zoom lens 1 of the present invention shown in the third to third E diagrams at the intermediate end. FIG. 4 and the aberration diagrams of the zoom lens 1 of the present invention shown in FIGS. 4A to 4E at the wide-angle end are designed according to the first numerical embodiment described above, and the astigmatism and distortion of the zoom lens 1 of the present invention are shown. Aberration, magnification chromatic aberration, spherical aberration, and comet aberration can all be well corrected.

The second numerical implementation of the zoom lens 1 of the present invention is shown in Table 4, Table 5, and Table 6 below.

According to the second numerical embodiment described above, the parameters of the zoom lens 1 of the present invention are as follows:

According to the above numerical calculation, it can be concluded that the value of the conditional expression (1) is 0.53, the value of the conditional expression (2) is 0.85, and the value of the conditional expression (3) is 6.97.

Please refer to the aberration diagrams of the zoom lens 1 of the present invention at the telephoto end shown in FIGS. 5A to 5E, and the aberration curves of the zoom lens 1 of the present invention at the intermediate end shown in FIGS. 6A to 6E. FIG. 7 and the aberration diagrams of the zoom lens 1 of the present invention shown in FIGS. 7A to 7E at the wide-angle end are designed according to the first numerical embodiment described above, and the astigmatism and distortion of the zoom lens 1 of the present invention are shown. Aberration, magnification chromatic aberration, spherical aberration, and comet aberration can all be well corrected.

In summary, the present invention has indeed met the requirements of the invention patent, and has filed a patent application according to law. However, the above description is only the preferred embodiment of the present invention, and equivalent modifications or variations made by those skilled in the art to the spirit of the present invention are included in the scope of the appended claims.

1. . . Zoom lens

G1. . . First lens group

G2. . . Second lens group

G3. . . Third lens group

G4. . . Fourth lens group

G5. . . Fifth lens group

GP. . . Glass plate

IP. . . Imaging surface

S. . . aperture

11, 14. . . Crescent type negative lens

12, 13. . . Crescent lug

15,20. . . Lenticular lens

16. . . Double concave lens

18, 21, 22, 24. . . Convex lens

19, 25. . . concave lens

twenty three. . . Double concave lens

100. . . Optical axis

101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 110', 111, 112, 113, 114, 115, 116, 117, 117', 118, 119, 120, 121, 122, 122', 123, 124, 125, 126, 127, 128, 129. . . surface

The first figure is a schematic view of the lens structure of the zoom lens of the present invention.

The second A to E E diagrams are schematic diagrams of the astigmatism, distortion, chromatic aberration, spherical aberration, and comet aberration formed by the zoom lens of the present invention at the telephoto end according to the first numerical embodiment.

The third to third E diagrams are schematic diagrams of the astigmatism, the distortion aberration, the chromatic aberration of magnification, the spherical aberration, and the comet aberration formed by the zoom lens of the present invention at the intermediate end according to the first numerical embodiment.

The fourth to fourth E drawings are graphs showing the curves of the astigmatism, the distortion aberration, the chromatic aberration of magnification, the spherical aberration, and the comet aberration formed by the zoom lens according to the first numerical embodiment according to the first numerical embodiment.

The fifth to fifth E diagrams are schematic diagrams of the astigmatism, the distortion aberration, the chromatic aberration of magnification, the spherical aberration, and the comet aberration formed by the zoom lens of the present invention at the telephoto end according to the second numerical embodiment.

6A to 6E are diagrams showing the curves of astigmatism, distortion, chromatic aberration of magnification, spherical aberration, and comet aberration formed at the intermediate end according to the second numerical embodiment of the zoom lens of the present invention.

7A to 7E are diagrams showing the curves of the astigmatism, the distortion aberration, the chromatic aberration of magnification, the spherical aberration, and the comet aberration formed at the wide angle end according to the second numerical embodiment of the zoom lens of the present invention.

1. . . Zoom lens

G1. . . First lens group

G2. . . Second lens group

G3. . . Third lens group

G4. . . Fourth lens group

G5. . . Fifth lens group

GP. . . Glass plate

IP. . . Imaging surface

S. . . aperture

11, 14. . . Crescent type negative lens

12, 13. . . Crescent lug

15,20. . . Lenticular lens

16. . . Double concave lens

18, 21, 22, 24. . . Convex lens

19, 25. . . concave lens

twenty three. . . Double concave lens

100. . . Optical axis

Claims (10)

A zoom lens comprising, in order from the object side to the image side, a first lens group having positive refracting power, a second lens group having negative refracting power, a third lens group having positive refracting power, and a fourth having negative refracting power a lens group; and a fifth lens group having positive refracting power; when the zoom lens is zoomed from the wide-angle end to the telephoto end, the first lens group and the third lens group both move toward the object side, the second lens group The fifth lens group is moved toward the image side; and when the object distance needs to be adjusted, the fourth lens group moves toward the image side; the zoom lens satisfies the following conditional expression: Wherein MG1 is the amount of movement of the first lens group from the wide-angle end to the telephoto end during zooming; fW is the focal length of the zoom lens at the wide-angle end; fT is the focal length of the zoom lens at the telephoto end; Y is the imaging surface The maximum diagonal length of the MG2 is the amount of movement of the second lens group from the wide-angle end to the telephoto end during zooming; fG2 is the focal length of the second lens group; MG3 is the third lens group from the wide-angle end to the zoom lens The amount of movement at the telephoto end; and fG3 is the focal length of the third lens group. The zoom lens of claim 1, wherein the first lens group comprises, in order from the object side, a crescent-shaped negative lens and a crescent-shaped convex lens. The zoom lens of claim 1, wherein the second lens group comprises, in order from the object side, a crescent-shaped negative lens, and a set of lens groups joined by a lenticular lens and a double concave lens. And a crescent-type negative lens, wherein the crescent-shaped negative lens of the second lens group on the image side includes at least one aspherical surface. The zoom lens according to claim 3, wherein both surfaces of the crescent-shaped negative lens on the image side of the second lens group are aspherical. The zoom lens according to claim 1, wherein the third lens group comprises, in order from the object side, a convex lens having at least one aspherical surface; and a set of a concave lens and a lenticular lens. a lens group; and a convex lens having at least one aspherical surface. The zoom lens according to claim 1, wherein the third lens group includes, in order from the object side, a convex lens whose surface facing the object side is an aspherical surface; and a set of a concave lens and a concave lens. a lens group in which lenticular lenses are joined; and a convex lens whose surface facing the image side is an aspherical surface. The zoom lens of claim 1, wherein the fourth lens group is formed by joining two spherical lenses. The zoom lens according to claim 7, wherein the fourth lens group includes, in order from the object side, a convex lens and a double concave lens. The zoom lens according to claim 1, wherein the fifth lens group comprises, in order from the object side, a convex lens and a concave lens, wherein a surface of the convex lens facing the object side is an aspherical surface. The zoom lens of claim 1, further comprising an aperture disposed between the second lens group and the third lens group, wherein the aperture is the third lens group during zooming Move together.