TW201219880A - composed of three lenses achieving miniaturization and providing high optical performance - Google Patents

Abstract

The present invention discloses a compact lens, which comprises a first lens, an aperture, a second lens and a third lens sequentially arranged from an object side to an image side along an optical axis. The first lens is made of glass material and has a positive diopter, and has at least one surface being an aspherical surface. The second lens is made of plastic material and has a positive diopter. The third lens is made of plastic material and has a negative diopter. In this way, the present invention may achieve the purposes of miniaturization and high optical performance.

Description

201219880 VI. Description of the Invention: [Technical Field] The present invention relates to an optical system. More specifically, it refers to a miniaturized lens composed of three mirrors. [Prior Art] In recent years, with advances in imaging technology, such as CCD (Charge coupled φ Device) or CMOS (Complementary Metal Oxide)

Semiconductors etc. are widely used in image pick-up apparatuses such as digital cameras or mobile phones. With the miniaturization of these imaging devices in recent years, the size of the above-described image capturing device and the lens applied to the above-described imaging device has also been greatly reduced. In addition, since the pixels of the image capturing device are getting higher and higher, the lens used for the image capturing device can also have higher optical performance, so that the image capturing device can be achieved. High resolution and high contrast. Therefore, miniaturization and high optical performance are two essential elements for the lens of imaging equipment. In the past, a lens consisting of one to two lenses was able to meet the needs of the image capture device at the time, but with the increase in the number of pixels, the lens with more lenses can meet the needs of high-quality. At present, the miniaturized lens used in imaging equipment consists of three lenses or four mirrors. Its towel, three-mirror type lens is small in size, but the optical performance is insufficient, and it can not meet the demand of high-quality materials. However, the four-lens mirror 3 201219880 has better optical performance, but its volume is three. The lens type lens is large, but it cannot achieve the purpose of effective miniaturization. Based on the above, it can be known that the known miniaturized lens is still unfinished and there is still room for improvement. SUMMARY OF THE INVENTION In view of the above, it is a primary object of the present invention to provide a miniaturized lens which is composed of three lenses', which is not only small in size but also has high optical efficiency. In order to achieve the above object, the miniaturized lens provided by the present invention comprises a first lens, an aperture, a second lens and a third arranged along the optical axis and sequentially arranged from the object side to the image side. a lens; the first lens is made of glass material having a positive refractive power, and at least the surface is an aspherical surface; the second lens is made of a plastic material and has a positive force; the third is made of a material, and With (10) light power for the purpose of cutting, shaping and high optical performance. [Embodiment] In order to explain the present invention more clearly, the preferred embodiment will be described in detail with reference to the accompanying drawings. 1 is a lens arrangement diagram of a miniaturized lens i of the present invention, and FIG. 2 is an optical path diagram of the embodiment of FIG. 1 , together with the drawings and FIG. 2, the first embodiment of the present invention will be described in detail below. Miniaturized lens j. The miniaturized lens 1 includes a first lens L1, an aperture ST, a second lens l2, and a third lens L3, which are disposed from the object side to the image side and are disposed along the optical axis Z. L3 can all be a single lens, or it can be a composite lens. It can also be a single lens for some lenses and a composite lens for some lenses. Further, a glass cover CG (c_ gamma) may be selectively disposed between the third lens L3 and the imaging plane Ip (Image Plane) according to the requirement of use, and is a flat glass. Wherein: the first lens L1 is made of glass material f, has a positive refractive power, and is a new meniscus aspherical lens, the object side S1 is convex, and the object side S1 and the image side S2 are both The aspherical surface satisfies the following condition: 0.2 < R1/F1 < 0.7 wherein R1 is the radius of the first lens L1 and F1 is the effective focal length of the first lens u. The first mirror 丨 L2 is made of a nano material and has a positive refractive power, and is a crescent-shaped aspherical mirror. The object side surface S4 is a concave surface, and the object side surface S4 and the image side surface ❶ S5 are aspherical surfaces. The third lens L3 is made of a plastic material, and its refractive power gradually changes from a negative force to a positive contact force from the optical axis z. In addition, the image side surface S7 of the third lens L3 is aspherical, and the radius of curvature of the optical axis region of the image side surface S7 (referring to the vicinity of the optical axis Z passing through and its predetermined range) is positive, from the light The radius of curvature from the shaft area to the circumference is negative. The surface of each of the lenses is close to the curvature at the optical axis Z, the thickness T of each lens on the optical axis, the 201219880 refractive index nd (refractive index) of each lens, and the Abbe's coefficient vd of each lens. (Abbe number) and the surface of each mirror M (Wei K (eGnie _ surface), as shown in Table 1: Table 1 Focus Length 2, Fno. = 2· 0

In Table 1, the surface numbers SI, S2 are the surfaces of the first lens L1; the surface number S3 refers to the surface of the aperture ST facing the second lens L2; the surface numbers S4 to S7 are sequentially the second lens L2 and The surface of the third lens L3; the surface numbers S8 and S9 are the two surfaces of the glass covering CG. The radius of curvature R shown in Table 1 is the radius of curvature at the corresponding surface on the optical axis z. The lens thickness T shown in Table 1, wherein the data corresponding to S1 is the thickness of the first lens L1 on the optical axis Z; the data corresponding to S2 is the first lens u and the second lens L2 on the optical axis Z. Spacing; the data corresponding to S4 is the thickness of the second 201219880 lens L2 on the optical axis Z; the data corresponding to S5 is the distance between the second lens L2 and the third lens L3 on the optical axis Z; the data corresponding to S6 is The thickness of the third lens L3 on the optical axis Z; the data corresponding to S7 is the distance between the third lens L3 and the glass cover CG on the optical axis Z; the data corresponding to S8 is the thickness of the glass cover CG; the data corresponding to S9 The distance between the CG and the imaging plane IP is covered by the glass. Further, the refractive index nd and the A-Bei coefficient vd corresponding to the surface numbers SI, S4, S6, and S8 are the refractive indices of the first lens L1, the second lens L2, the third lens L3, and the glass-covered CG, respectively. coefficient. The surface depression z of the aspherical surfaces S1, S2, s4, S5 and S7 in the respective lenses of the present embodiment is obtained by the following formula:

+ + Bh 6 + Chs + Dh

Where: z: the degree of depression of the aspherical surface; c: the reciprocal of the radius of curvature; h: the aperture radius of the surface; k: the conic coefficient; A~I: the coefficient of the order of the aperture radius h of the surface. Although the coefficient k (conic I is as shown in Table 2: in this embodiment, the cone of each aspherical surface is constant) and the surface aperture radius h are various order coefficients A~7 201219880 Surface number KABCDEFG Η I S1 0. 20959 -0 20595 4.41088 -234. 642 4960.1 -54847.8 294576.8 -620737 0 0 S2 23. 2451 -1.18024 -19.0345 1300. 624 -65621 1356204 -1.3E+07 42218483 0 0 S4 -1.36954 -4. 87369 -337. 963 21017.89 - 969465 28352692 4.47E+08 2.88E+09 0 0 S5 -5.9396 *24.464 468.7591 -5843 5514.161 795085.1 -8406772 28275673 0 0 S7 0. 035569 -10.9993 102.5343 -870. 957 4762. 94 -16131.8 30376.3 -24392.1 0 0 by The lens and aperture arrangement described above makes the miniaturized lens 1 of the present embodiment not only effective in reducing the volume for miniaturization, but also in imaging quality, as can be seen from FIGS. 3A to 3C. FIG. 3A is a field curvature diagram and a distortion diagram of the miniaturized lens 1 of the embodiment; FIG. 3B is a defocusing modulation Lu transfer function diagram (ThroughFocusMTF) of the miniaturized lens of the embodiment; 3C is a spatial frequency modulation transfer function diagram (Spatial Frequency MTF) of the miniaturized lens 1 of the present embodiment. As can be seen from Fig. 3A, the maximum field curvature of this embodiment does not exceed 0.04 mm and -0.04 faces, and the distortion variable does not exceed 2%. As can be seen from Fig. 3B, this embodiment has a good resolution regardless of the field of view position. It can be seen from Fig. 3c that the value of the modulation optical transfer function of the present embodiment is maintained at 5 G% or more at 113.5 lp/_, and it is apparent that the resolution of the miniaturized lens of this embodiment is in accordance with the standard. The above is a miniaturized lens 1 of the first embodiment of the present invention; according to the technology of the present invention, the second embodiment of the present invention will be described below with reference to FIGS. 4 and 5, and the present invention is the same as the first embodiment. The miniaturized lens 2 of the second embodiment includes a first lens L1, a light 8 201219880 circle st, a second lens L2, and a third lens u, which are disposed from the object side to the image side and along the optical axis Z. A glass-covering CG of a system-flat surface is also provided between the third lens L3 and the imaging plane IP. Wherein: the first lens L1 has a positive refractive power, and is a crescent-shaped glass aspherical mirror whose object side si is convex and the object side surface S1 and the image side surface are all aspherical surfaces, and the following conditions are also satisfied: 0.2<R1/F1<0.7 where R1 is the radius of the first lens L1 and F1 is the effective focal length of the first lens u. The first lens L2 has a positive contact force and is a crescent-shaped plastic aspherical mirror whose object side ® S4 is a concave surface and both the object side surface S4 and the image side surface are aspherical. The second lens L3 is a plastic aspherical mirror whose image side S7 is aspherical, and the radius of curvature of the light field of the image side S7 is positive, and the radius of the alcohol from the optical axis region to the periphery of the third lens L3 is negative. value. Further, the third lens L3 is hidden from the optical axis Z _ to the hiding power, and its refractive power is gradually converted into positive refractive power by the 贞. The surface of each of the lenses is close to the radius of curvature R at the optical axis (the thickness of the lens is 〇f curvature), the thickness τ (thickness) of each lens on the optical axis, the refractive index nd (refractive index) of each lens, and the Abbe of each lens. The coefficient vd (Abbe number) and the conical coefficient κ (c〇nic constat) of each lens surface are shown in Table 3: 201219880

-4. 37657 S7 0.63348 S8 Infinity 0.261625 257695 0.108232 0. 00267f S9

Infinity 1.514648

In Table 3, the surface numbers sT and S2 are the number S3, which refers to the surface of the aperture ST facing the side of the second mirror 4 L2; the surface numbers S4 to S7 are the surfaces of the second lens L2 and the third lens ^, respectively. Surface numbers S8 and S9 are the two surfaces of the glass covering the CG. The radius of curvature r, which is not shown in Table 3, is the radius of curvature at the corresponding surface on the optical axis z. The lens thickness T shown in Table 3, wherein the data corresponding to si is the thickness of the first lens L1 on the optical axis Z; the data corresponding to S2 is the first lens L1 and the second lens L2 on the optical axis Z. Spacing; the data corresponding to S4 is the thickness of the second lens L2 on the optical axis Z; the data corresponding to S5 is the distance between the second lens L2 and the third lens L3 on the optical axis Z; the data corresponding to S6 is the first The thickness of the three lenses L3 on the optical axis Z; the data corresponding to S7 is the distance between the third lens L3 and the glass cover CG on the optical axis Z; the data corresponding to S8 is the thickness of the glass cover 201219880 cover CG; corresponding to S9 The data is the distance between the glass overlay CG and the imaging plane IP. Further, the refractive index nd and the Abbe's coefficient vd corresponding to the surface numbers SI, S4, S6, and S8 are the refractive indices and Abbe coefficients of the first lens L1, the second lens L2, the third lens L3, and the glass-covered CG, respectively. . The surface depression z of the aspherical surfaces SI, S2, S4, S5 and S7 in the respective lenses of the present embodiment is obtained by the following formula: c/z 2

, Γ τ~ Ship 4 + 劢6 + to 8 + gamma 10 + 劢12 + 劢14 + (3)16 + off 18 + calendar 20 1 + [1 - + \)c2h2Y where: Z: aspherical surface depression; C : reciprocal of radius of curvature; h: aperture radius of the surface; k: conic coefficient; A~I: various order coefficients of the aperture radius h of the surface. In this embodiment, the conic coefficients k (conic constant) of each aspheric surface and the order coefficients A to I of the surface aperture radius h are as shown in Table 4: Table 4 surface number KABCDEFG Η I S1 0.211264 -0. 02663 0.149875 - 2.05345 11.22061 -32.0639 44.47449 -24.2054 0 0 S2 23. 24512 -0.15436 -0. 6434 11.39285 -148. 497 792.5914 -1915.19 1648.26 0 0 S4 -1.35052 -0. 6429 -11.405 183.8942 -2191.99 16553.09 -67343.3 112302.2 0 0 S5 - 5. 97934 -3.20955 15.88464 -51.1466 12. 52532 464.802 -1268.7 1101.281 0 0 S7 0. 041188 -1.44107 3.475569 -7. 62869 10.77752 -9. 42849 4. 584783 -0.95119 0 0 201219880 With the lens and aperture configuration described above, The miniaturized lens 2 of the present embodiment can be effectively reduced in size by miniaturization, and can also meet the requirements in image quality, as can be seen from FIGS. 6A to 6C. FIG. 6A is a field curvature diagram and a distortion diagram of the miniaturized lens 2 of the embodiment; FIG. 6B is a defocus modulation transfer function diagram (ThroughFocusMTF) of the miniaturized lens 2 of the embodiment; 6C shows the spatial frequency modulation transfer function map (Spatial Frequency MTF) of the miniaturized lens 2 of the present embodiment. As can be seen from Fig. 6A, the maximum field curvature of this embodiment does not exceed 0.06 mm and -0.04 mm, and the distortion variable does not exceed 2%. As can be seen from Figure 6B,

In this embodiment, no matter which field of view has a good resolution, it can be seen from FIG. 6C that when the present embodiment is at (1).5 lp/mm, the modulation optical transfer function value is maintained at 3 () as above, and this embodiment is apparent. For example, the resolution of the small touch surface 2 is in accordance with the standard. As can be seen from the above detailed description, the miniaturized lens of the present invention is not only small in size but also more highly optically efficient, so as to meet the demand for imaging equipment. It is a preferred embodiment of the present invention, and the equivalent structure and manufacturing method of the application of the present invention are modified, and the package 3 is within the scope of the patent of the present invention. 201219880 [Simplified description of the drawings] *1 1 is a lens arrangement diagram of a miniaturized lens according to a first embodiment of the present invention. FIG. 2 is an optical path diagram of a first embodiment of the present invention. FIG. 3A is a field curvature representation of the first embodiment of the present invention. FIG. 3B is a diagram showing a defocusing modulation transfer function according to a first embodiment of the present invention. FIG. 3C is a diagram showing a spatial frequency modulation transfer function according to a first embodiment of the present invention. FIG. 4 is a miniaturized surface according to a second embodiment of the present invention. FIG. 5 is a view of a second embodiment of the present invention. FIG. 6 is a view of a field curvature and a distortion diagram of a second embodiment of the present invention. FIG. 6B is a diagram of a modulation transfer function of the second day of the present invention. 6C is the spatial frequency modulation transfer function of the second embodiment of the present invention. FIG. 13 201219880 [Major component symbol description] 1 miniaturized lens L1 first lens L2 second lens L3 third lens CG glass cover IP imaging plane ST aperture S1 to S9 Face miniaturized lens L1 first lens L2 second lens L3 third lens CG glass cover Π > imaging plane ST aperture S1 to S9 surface Z optical axis 14

Claims (1)

201219880 VII. Patent application scope: 1. A miniaturized lens, which comprises an edge-optical axis and is arranged from the object side to an image sequence: a first-lens is made of glass material, has positive refractive power, and at least An aspherical surface; _ an aperture; a second lens 'made of plastic material' and having positive refractive power; • a third lens made of plastic material and having a negative refractive power. 2. The miniaturized lens of claim 1, which satisfies the following condition: 0.2 < R1/F1 < 〇.7 ’ where 'r! is the radius of the first lens and is the effective focal length of the first lens. 3. The miniaturized lens of claim 1, wherein at least one side of the second lens is an aspherical surface. 4. The miniaturized lens of claim 1, wherein the third lens has at least a hetero-aspherical surface and the refractive power is gradually converted from a negative refractive power to a positive refractive power from a point where the optical axis passes to a periphery thereof. 5. The miniaturized lens according to claim 1, wherein an optical axis region of the surface of the third lens located on the image side (referring to an adjacent region including the optical axis passing through and a predetermined range thereof) has a positive radius of curvature The radius of curvature from the region to the periphery of the third lens is a negative value. 15