TW202036074A - Optical lens - Google Patents

Abstract

An optical lens includes a first lens, a second lens, and a third lens, from an object side to an image side along an optical axis. The first lens is a lens having negative refractive power, and an object-side surface of the first lens is concave. The second lens is a lens having positive refractive power. The third lens is a lens having positive refractive power, and an image-side surface of the third lens is convex. The optical lens satisfies a condition, i.e., 3 < D1/f < 6, where D1 is an optical effective diameter of the first lens and f is an effective focal lens of the optical lens. The optical lens is characterized by wide angle and short object distance.

Description

Optical lens (5)

The present invention relates to an optical element, in particular to an optical lens.

In recent years, imaging equipment has been widely used. Various smart devices (such as smart phones, tablets and wearable devices) are equipped with imaging equipment, and even an electronic device is equipped with multiple imaging equipment or optical lenses. And optical imaging system groups with different characteristics are gradually being developed to meet various needs.

For example, smart devices need to verify the user's identity during operation to prevent the device from being stolen. For identity verification technology, in addition to the traditional way of entering account and password, the use of fingerprint recognition is becoming more and more popular, and this method is also faster and more convenient. Applied to smart devices, the common capacitive fingerprint recognition has matured, but the capacitive fingerprint recognition must have an additional fingerprint recognition area set up on the device, which cannot be set directly under the display panel. Fingerprint recognition under the screen can be realized through optical fingerprint recognition. In this way, an imaging device or an optical lens is set under the display panel to capture fingerprint images. The quality of the optical lens is related to the accuracy of fingerprint recognition. The development of such optical lenses has become one of the important topics in this field.

The purpose of the present invention is to provide an optical lens, which has the characteristics of wide-angle and short object distance, and is suitable for the technical fields of optical identification, macro observation, and biomedical detection.

The optical lens provided by the present invention wraps sequentially on the optical axis from the object side to the image side. Including: a first lens, a second lens and a third lens. The first lens is a lens with negative refractive power and its object side surface is concave, the second lens is a lens with positive refractive power, and the third lens is a lens with positive refractive power and its image side surface is convex. The optical lens satisfies the following conditional formula: 3<D1/f<6, where D1 is the optical effective diameter of the first lens, and f is the effective focal length of the optical lens.

In an embodiment of the present invention, at least one of the object side surface and the image side surface of the first lens has an inflection point, the image side surface of the first lens is concave, the first lens is a biconcave lens; the second lens The object side surface of the lens is concave, the image side surface of the second lens is convex, the second lens is a meniscus lens; the object side surface of the third lens is convex, and the third lens is a biconvex lens.

In the embodiment of the present invention, the optical lens satisfies the following conditional formula: 0.7<OD/TTL<1.2, where OD is the distance from the object side surface of the first lens to the object to be measured on the optical axis, and TTL is the optical lens The total length.

In the embodiment of the present invention, the optical lens satisfies the following conditional formula: 3.2<D1/IH<3.8, where D1 is the optical effective diameter of the first lens, and IH is the maximum imaging height of the optical lens on the imaging plane.

In the embodiment of the present invention, the optical lens satisfies the following conditional expressions: 10<f2/f<14; and 8.5<(f1+f2+f3)/f<15, where f1 is the effective focal length of the first lens, and f2 is The effective focal length of the second lens, f3 is the effective focal length of the third lens, and f is the effective focal length of the optical lens.

In the embodiment of the present invention, the optical lens satisfies the following conditional formula: 4<TTL/AAG<7, where TTL is the total length of the optical lens, and AAG is the first lens and the second lens The sum of the air gap between the two lenses on the optical axis and the air gap between the second lens and the third lens on the optical axis.

In the embodiment of the present invention, the optical lens satisfies the following conditional formula: 4<TTL/f<7, where TTL is the total length of the optical lens, and f is the effective focal length of the optical lens.

In the embodiment of the present invention, the optical lens satisfies the following conditional formula: 5<f2/f3<10, where f2 is the effective focal length of the second lens, and f3 is the effective focal length of the third lens.

In the embodiment of the present invention, the optical lens satisfies the following conditional formula: 4<f/TC23<6, where f is the effective focal length of the optical lens, and TC23 is the image side surface of the second lens to the object side of the third lens The distance between the surface and the optical axis.

In the embodiment of the present invention, the optical lens further includes an aperture set between the second lens and the third lens, wherein the optical lens satisfies the following conditional formula: 0.5<SD/T1<1, where SD is the aperture The distance from the image side surface of the third lens on the optical axis, and T1 is the center thickness of the first lens on the optical axis.

The optical lens of the present invention can expand the field of view, reduce aberrations, and improve the resolution. The optical lens of the present invention only needs three lenses at least, and has the advantages of small number of components and easy miniaturization. In some applications, such as screen The optical recognition function of the next fingerprint.

G‧‧‧Protection glass

GL‧‧‧Plate transparent parts

IMA‧‧‧imaging plane

L1‧‧‧First lens

L2‧‧‧Second lens

L3‧‧‧third lens

OA‧‧‧Optical axis

STO‧‧‧Aperture

S1‧‧‧Object side surface of the first lens

S2‧‧‧The image side surface of the first lens

S3‧‧‧Object side surface of second lens

S4‧‧‧Second lens image side surface

S6‧‧‧Object side surface of third lens

S7‧‧‧Third lens image side surface

Figure 1 shows a schematic diagram of an optical lens according to the present invention.

FIG. 2A shows a schematic diagram of the optical lens according to the first embodiment of the present invention.

The 2B to 2D images are respectively the field curvature, distortion and lateral chromatic aberration diagrams of the first embodiment in sequence.

FIG. 3A shows a schematic diagram of an optical lens according to a second embodiment of the invention.

The 3B to 3D images are respectively the field curvature, distortion and lateral chromatic aberration diagrams of the second embodiment in sequence.

FIG. 4A shows a schematic diagram of an optical lens according to a third embodiment of the invention.

Figures 4B to 4D are respectively the field curvature, distortion and lateral chromatic aberration diagrams of the third embodiment in sequence.

FIG. 5A shows a schematic diagram of an optical lens according to a fourth embodiment of the invention.

Figures 5B to 5D are respectively the curvature of field, distortion and lateral chromatic aberration diagrams of the fourth embodiment in sequence.

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

The present invention provides an optical lens, which has the characteristics of wide angle and short object distance, and can be realized as a lens with the characteristics of miniature, single focus or large aperture, which can be applied to personal information terminals such as mobile phones, smart phones, and tablet computers , Wearable devices and various image capturing devices equipped with lenses are realized in the technical fields of optical identification, macro observation and biomedical testing. For example, the optical lens of the present invention can be arranged under the display panel to realize the optical recognition of fingerprints under the screen, as a key component of the relevant device for fingerprint recognition under the screen.

The present invention provides an optical lens, which sequentially includes a first lens, a second lens, and a third lens on the optical axis from the object side to the image side. The first lens is a lens with negative refractive power and its object side surface is concave, the second lens is a lens with positive refractive power, and the third lens is a lens with positive refractive power, and its image side surface is convex. The optical lens satisfies the following conditional formula: 3<D1/f<6, where D1 is the optical effective diameter of the first lens, and f is the effective focal length of the optical lens.

Referring to FIG. 1, the optical lens of the present invention includes a first lens L1, a second lens L2, and a third lens L3 in order from the object side to the image side along the optical axis OA. Preferably, the first lens L1 is a lens with negative refractive power, the second lens L2 is a lens with positive refractive power, and the third lens L3 It is a lens with positive refractive power. In addition, the optical lens also includes an aperture STO located between the image-side surface of the second lens L2 and the object-side surface of the third lens L3, and the third lens L3 and the imaging plane IMA (the light from the object side is finally imaged in the image The protective glass G between the plane IMA. However, the setting position of the aperture STO is not limited to this, and it can also be set at other suitable positions. The protective glass G can also be a filter.

In one embodiment, the optical lens has a single focus, which is a single focus lens. On the optical axis OA, at a distance from the object side surface of the first lens L1 on the side close to the object side, a flat transparent piece (the material of which is glass, for example) can be arranged, and the object to be measured can be placed on the flat transparent piece Above, imaging is performed with a fixed object distance, which facilitates the formation of clear images on the imaging plane IMA.

In one embodiment, the object side surface of the first lens L1 is concave, and the image side surface is concave, forming a lens with negative refractive power. The first lens L1 can be made of plastic material, and at least one of the object side surface and the image side surface can be an aspheric surface (ASP). The first lens L1 may also be a composite lens composed of glass and plastic. For example, the object side surface of the first lens L1 is formed of plastic material, and the image side surface is formed of glass material. In addition, at least one of the object side surface and the image side surface of the first lens L1 may have an inflection point. For example, the inflection point is located on the object side surface of the first lens L1.

In one embodiment, the object side surface of the second lens L2 is concave, and the image side surface is convex, forming a lens with positive refractive power. The second lens L2 may be made of plastic material or a composite lens composed of glass and plastic. For example, the object side surface of the second lens L2 is formed of glass material, and the image side surface is formed of plastic material.

In one embodiment, the object side surface of the third lens L3 is convex, and the image side surface is convex, forming a lens with positive refractive power. For example, the third lens L3 is a biconvex lens. third The lens L3 can be made of plastic material or a composite lens composed of glass and plastic, and at least one of the object side surface and the image side surface can be an aspherical surface.

The object side surface and image side surface of each lens L1, L2, and L3 in the optical lens can be aspherical surfaces. The aspherical surface can obtain more control variables to reduce aberrations. Each lens L1, L2, and L3 can be They are all plastic lenses, which maintain excellent resolution quality while reducing costs. Of course, each lens L1, L2, and L3 can also be realized by a glass lens, or a compound lens composed of plastic and glass.

The shape of the aspheric lens can be expressed by the following formula:

Where D represents the sag of the aspheric lens relative to the height from the central axis of the lens, C represents the reciprocal of the paraxial curvature radius, H represents the relative height of the aspheric lens from the central axis of the lens, and K represents the relative height of the aspheric lens Conic Constant, and E ₄ ~ E _{12 are} even-numbered aspheric correction coefficients above the fourth order.

The optical lens of the present invention can expand the field of view, reduce aberrations, and improve the resolution. The optical lens of the present invention only needs three lenses at least, and has the advantages of small number of components and easy miniaturization. In some applications, such as screen The optical recognition function of the next fingerprint.

Specific embodiments will be given below to further describe the optical lens of the present invention in detail.

Please refer to FIGS. 2A to 2D. FIG. 2A shows a schematic diagram of the optical lens according to the first embodiment of the present invention. FIGS. 2B to 2D are respectively the field curvature of the first embodiment, Diagram of distortion and lateral chromatic aberration. Please refer to Figure 2A. The optical lens of the first embodiment of the present invention includes a first lens L1 with negative refractive power, a second lens L2 with positive refractive power, and an aperture along the optical axis OA from the object side to the image side. STO, a third lens L3 with positive refractive power, and protective glass (or filter) G. Specifically, the object side surface S1 of the first lens L1 is concave, the image side surface S2 is concave, the first lens L1 is a biconcave lens, the object side surface of the first lens L1 has an inflection point, and the second lens L2 The object-side surface S3 is concave, the image-side surface S4 is convex, the second lens L2 is a meniscus lens, the object-side surface S6 of the third lens L3 is convex, the image-side surface S7 is convex, and the third lens L3 is a Double convex lens. The object side surface S8 and the image side surface S9 of the protective glass (or filter) G are both flat.

The optical lens of the first embodiment of the present invention satisfies any one of the following conditional expressions: 0.7<OD/TTL<1.2 (1)

3.2<D1/IH<3.8 (2)

10<f2/f<14 (3)

8.5<(f1+f2+f3)/f<15 (4)

4<TTL/AAG<7 (5)

4<TTL/f<7 (6)

3<D1/f<6 (7)

4<f/TC23<6 (8)

5<f2/f3<10 (9)

0.5<SD/T1<1 (10)

Among them, OD is the distance from the object side surface S1 of the first lens L1 to the optical axis OA (that is, the object distance of the optical system of the optical lens), and TTL is the total length of the optical lens (that is, the object of the first lens L1) The distance from the side surface S1 to the imaging plane IMA on the optical axis OA), D1 is the optical effective diameter of the first lens L1, IH is the maximum imaging height (maximum imaging circle radius) of the optical lens in the imaging plane IMA, f1 is the The effective focal length of a lens L1, f2 is the effective focal length of the second lens L2, f3 is the effective focal length of the third lens L3, f is the effective focal length of the optical lens, and AAG is the distance between the first lens L1 and the second lens L2 The air gap on the optical axis OA and the difference between the second lens L2 and the third lens L3 The sum of the air gaps between the optical axis OA (ie the sum of the air gaps between the first lens L1 to the third lens L3), TC23 is the image side surface S4 of the second lens L2 to the object side surface of the third lens L3 S6 is the distance on the optical axis OA, SD is the distance from the aperture STO to the image side surface S7 of the third lens L3 on the optical axis OA, and T1 is the center thickness value of the first lens L1 on the optical axis OA.

By using the above lens and satisfying any of the conditional expressions (1) to (10), the optical lens can have wide-angle and short object distance characteristics, reduce aberrations, and improve resolution.

Table 1 is the parameter table of the optical lens in Figure 2A, Table 2 is the relevant parameter table of each lens of the optical lens, and Table 3 is the relevant parameter table of the aspheric surface of each lens in Table 2.

Table 4 shows the values calculated according to conditional formulas (1)~(10) for each parameter of the optical lens of the first embodiment. It can be seen from Table 4 that the optical lens of the first embodiment satisfies conditional formulas (1)~( 10) Requirements.

In addition, the optical performance of the optical lens of the first embodiment can also meet the requirements, which can be seen from Figures 2B to 2D. It can be seen from Figure 2B that the curvature of field of the optical lens of the first embodiment is between -0.07mm and -0.01mm. It can be seen from Figure 2C that the distortion of the optical lens of the first embodiment is between -32% and 1%. It can be seen from Figure 2D that the lateral chromatic aberration value of the optical lens of the first embodiment is between -4.9 μm and 0 μm. It is obvious that the curvature of field, distortion, and lateral chromatic aberration of the optical lens of the first embodiment can be effectively corrected, and the resolution of the lens can also meet the requirements, thereby obtaining better Optical performance.

Please refer to FIGS. 3A to 3D. FIG. 3A shows a schematic diagram of an optical lens according to the second embodiment of the present invention. FIGS. 3B to 3D are respectively the curvature of field, distortion and lateral chromatic aberration diagrams of the second embodiment in sequence. . The refractive properties and surface shapes of the lenses L1, L2, and L3 in the second embodiment of the present invention are similar to those of the first embodiment, and will not be repeated. In the second embodiment of the present invention, on the optical axis OA, a flat transparent member GL is provided at a distance from the object side surface S1 of the first lens L1 on the side close to the object side. The optical lens of the second embodiment is a single focus lens. In order to facilitate the formation of a clear image on the imaging plane IMA, the object to be measured can be placed on the flat transparent member GL, so that the object distance is fixed during the imaging process.

Table 5 is the parameter table of the optical lens in Figure 3A, Table 6 is the relevant parameter table of each lens of the optical lens, and Table 7 is the relevant parameter table of the aspheric surface of each lens in Table 6.

Table 8 shows the values calculated according to conditional formulas (1)~(10) for each parameter of the optical lens of the second embodiment. It can be seen from Table 8 that the optical lens of the second embodiment satisfies conditional formulas (1)~( 10) Requirements.

In addition, the optical performance of the optical lens of the second embodiment can also meet the requirements, which can be seen from Figures 3B to 3D. It can be seen from FIG. 3B that the curvature of field of the optical lens of the second embodiment is between -0.061mm and 0.01mm. It can be seen from Figure 3C that the distortion of the optical lens of the second embodiment is between -5% and 0%. It can be seen from the 3D diagram that the lateral chromatic aberration value of the optical lens of the second embodiment is between -3.9 μm and 0 μm. It is obvious that the curvature of field, distortion, and lateral chromatic aberration of the optical lens of the second embodiment can be effectively corrected, and the lens resolution can also meet the requirements, thereby obtaining better optical performance.

Please refer to FIGS. 4A to 4D. FIG. 4A shows a schematic diagram of an optical lens according to the third embodiment of the present invention. FIGS. 4B to 4D are respectively the curvature of field, distortion, and lateral chromatic aberration diagrams of the third embodiment in sequence. . The refractive properties and surface shapes of the lenses L1, L2, and L3 in the third embodiment of the present invention are similar to those of the first embodiment, and will not be repeated.

Table 9 is the parameter table of the optical lens in Figure 4A, Table 10 is the relevant parameter table of each lens of the optical lens, and Table 11 is the relevant parameter table of the aspheric surface of each lens in Table 10.

Table 12 shows the values calculated by the optical lens of the third embodiment according to the conditional formulas (1)~(10). From Table 12, it can be seen that the optical lens of the third embodiment satisfies the conditional formula (1) ~(10) Requirements.

In addition, the optical performance of the optical lens of the third embodiment can also meet the requirements, which can be seen from Figures 4B to 4D. It can be seen from Figure 4B that the curvature of field of the optical lens of the third embodiment is between -0.04mm and 0.03mm. It can be seen from FIG. 4C that the distortion of the optical lens of the third embodiment is between -15% and 0%. It can be seen from FIG. 4D that the lateral chromatic aberration value of the optical lens of the third embodiment is between -4 μm and 0 μm. It is obvious that the curvature of field, distortion, and lateral chromatic aberration of the optical lens of the third embodiment can be effectively corrected, and the lens resolution can also meet the requirements, thereby obtaining better optical performance.

Please refer to FIGS. 5A to 5D. FIG. 5A shows a schematic diagram of an optical lens according to the fourth embodiment of the present invention. FIGS. 5B to 5D are respectively the curvature of field, distortion and lateral chromatic aberration diagrams of the fourth embodiment in sequence. . The refractive properties and surface shapes of the lenses L1, L2, and L3 in the fourth embodiment of the present invention are similar to those of the first embodiment, and will not be repeated.

Table 13 is the parameter table of the optical lens in Figure 5A, Table 14 is the relevant parameter table of each lens of the optical lens, and Table 15 is the relevant parameter table of the aspheric surface of each lens in Table 14.

表十三

Table 13

Table 16 shows the values calculated by the optical lens of the fourth embodiment according to conditional formulas (1)~(10). It can be seen from Table 16 that the optical lens of the fourth embodiment satisfies the conditional formula (1) ~(10) Requirements.

In addition, the optical performance of the optical lens of the fourth embodiment can also meet the requirements, which can be seen from Figures 5B to 5D. It can be seen from FIG. 5B that the curvature of field of the optical lens of the fourth embodiment is between -0.07mm and 0.03mm. It can be seen from FIG. 5C that the distortion of the optical lens of the fourth embodiment is between -5% and 0%. It can be seen from FIG. 5D that the lateral chromatic aberration value of the optical lens of the fourth embodiment is between -4 μm and 0 μm. It is obvious that the curvature of field, distortion, and lateral chromatic aberration of the optical lens of the fourth embodiment can be effectively corrected, and the lens resolution can also meet the requirements, thereby obtaining better optical performance.

Although the present invention has been disclosed in the above preferred embodiments, it is not intended to limit the present invention. Those with ordinary knowledge in the technical field of the present invention can make various changes and modifications without departing from the spirit and scope of the present invention. Retouching, therefore, the scope of protection of the present invention shall be subject to the scope of the attached patent application.

G‧‧‧Protection glass

IMA‧‧‧imaging plane

L1‧‧‧First lens

L2‧‧‧Second lens

L3‧‧‧third lens

OA‧‧‧Optical axis

STO‧‧‧Aperture

Claims (10)

An optical lens, which sequentially includes on the optical axis from the object side to the image side: a first lens, which is a lens with negative refractive power, and its object side surface is concave; and a second lens, which is a positive refractive power lens Lens; and a third lens, which is a lens with positive refractive power, the image side surface is convex; wherein the optical lens satisfies the following conditional formula: 3<D1/f<6, where D1 is the optical effectiveness of the first lens Diameter, f is the effective focal length of the optical lens. The optical lens according to claim 1, wherein at least one of the object side surface and the image side surface of the first lens has an inflection point, the image side surface of the first lens is concave, and the first lens Is a biconcave lens; the object-side surface of the second lens is concave, the image-side surface of the second lens is convex, the second lens is a meniscus lens; the object-side surface of the third lens is convex, the The third lens is a biconvex lens. The optical lens described in item 2 of the scope of patent application, wherein the optical lens satisfies the following conditional formula: 0.7<OD/TTL<1.2, where OD is the object side surface of the first lens to the object to be measured on the optical axis TTL is the total length of the optical lens. The optical lens described in item 1 of the scope of patent application, wherein the optical lens satisfies the following conditional formula: 3.2<D1/IH<3.8, where D1 is the optical effective diameter of the first lens, and IH is the optical lens in the imaging plane The maximum imaging height. For the optical lens described in item 2 of the scope of patent application, the optical lens satisfies the following conditional formula: 10<f2/f<14; and 8.5<(f1+f2+f3)/f<15, where f1 is the first The effective focal length of a lens, f2 is the effective focal length of the second lens, f3 is the effective focal length of the third lens, and f is the effective focal length of the optical lens. The optical lens described in item 3 of the scope of patent application, wherein the optical lens satisfies the following conditional formula: 4<TTL/AAG<7, where TTL is the total length of the optical lens, and AAG is the first lens and the second lens The sum of the air gap between the lenses on the optical axis and the air gap between the second lens and the third lens on the optical axis. For the optical lens described in item 6 of the scope of patent application, the optical lens satisfies the following conditional formula: 4<TTL/f<7, where TTL is the total length of the optical lens, and f is the effective focal length of the optical lens. The optical lens described in item 1 of the scope of patent application, wherein the optical lens satisfies the following conditional formula: 5<f2/f3<10, where f2 is the effective focal length of the second lens, and f3 is the effective focal length of the third lens . The optical lens described in item 8 of the scope of patent application, wherein the optical lens satisfies the following Conditional expression: 4<f/TC23<6, where f is the effective focal length of the optical lens, and TC23 is the distance on the optical axis from the image side surface of the second lens to the object side surface of the third lens. The optical lens described in item 1 of the scope of the patent application further includes an aperture set between the second lens and the third lens, wherein the optical lens satisfies the following conditional formula: 0.5<SD/T1<1, where SD is the distance from the aperture to the image side surface of the third lens on the optical axis, and T1 is the center thickness value of the first lens on the optical axis.

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