CN105824107B - Optical imaging system, imaging device and electronic device - Google Patents

Abstract

The present invention discloses an optical imaging system, an imaging device and an electronic device. The optical imaging system includes a first lens, a second lens and a third lens with refractive power in order from the object side to the image side. The first lens has positive refractive power, and its object side surface is convex at the near optical axis, and its image side surface is convex at the near optical axis. Both surfaces are aspherical and made of plastic. The second lens has positive refractive power, and its object side surface is concave at the near optical axis, and its image side surface is convex at the near optical axis. Both surfaces are aspherical and made of plastic. The third lens has negative refractive power, and its image side surface is concave at the near optical axis, and its image side surface has at least one convex surface off the axis. Both surfaces are aspherical and made of plastic. The optical imaging system has three lenses with refractive power. The optical imaging system further includes an aperture, which is arranged between the image side surface of the first lens and the object side surface of the second lens. The present invention also discloses an imaging device having the above-mentioned optical imaging system and an electronic device having the imaging device.

Description

Optical imaging system, imaging device and electronic device

technical field

The invention relates to an optical imaging system, an imaging device and an electronic device, in particular to an optical imaging system and an imaging device suitable for electronic devices.

Background technique

In recent years, with the vigorous development of miniaturized photographic lenses, the demand for miniature imaging modules has been increasing day by day, and the photosensitive elements of general photographic lenses are nothing more than charge coupled devices (CCD) or complementary metal oxide semiconductor elements. (Complementary Metal-Oxide Semiconductor Sensor, CMOS Sensor) two types, and with the improvement of semiconductor process technology, the pixel size of the photosensitive element is reduced. In addition, today's electronic products are developing with good functions and thin, light and short appearance. Therefore, miniaturized photographic lenses with good imaging quality have become the mainstream in the current market.

Traditional high-resolution miniaturized photographic lenses mounted on electronic devices mostly use a two-piece lens structure. ) and infrared photographic lenses and other high-standard mobile devices have led to higher requirements for miniaturized camera lenses in terms of pixels and imaging quality. The existing two-piece lens group will not be able to meet higher-level requirements.

At present, although there is a general traditional three-piece optical system, the uneven distribution of refractive power in the existing optical system easily makes the back focal length of the optical system too long, which is not conducive to the miniaturization of the optical system. Furthermore, the refractive power may be excessively concentrated on a single lens, which hinders the correction of the aberration of the optical system and reduces the sensitivity of the optical system.

Contents of the invention

The object of the present invention is to provide an optical imaging system, an imaging device and an electronic device, wherein the optical imaging system includes a first lens with positive refractive power, a second lens with positive refractive power and a first lens with negative refractive power Three lenses, and the refractive power of the third lens is stronger than that of the first lens and the second lens. Thereby, the total length and back focus of the optical imaging system can be effectively shortened. In addition, when specific conditions are met, it is helpful to make the refractive power configuration of the lens in the optical imaging system more balanced, so as to correct the aberration of the optical imaging system and reduce the sensitivity of the optical imaging system. Furthermore, both the object-side surface and the image-side surface of the first lens are convex, which can effectively balance the curvature distribution of the first lens and help avoid the curvature of a single surface of the first lens being too strong, so as to reduce the generation of aberrations in the optical imaging system , and reduce the difficulty of molding.

The invention provides an optical imaging system, which sequentially includes a first lens, a second lens and a third lens from the object side to the image side. The first lens has positive refractive power, its object-side surface is convex at the near optical axis, its image-side surface is convex at the near optical axis, its object-side surface and image-side surface are both aspherical, and the first lens is Plastic material. The second lens has positive refractive power, its object-side surface is concave at the near optical axis, its image-side surface is convex at the near optical axis, its object-side surface and image-side surface are both aspherical, and the second lens is Plastic material. The third lens has negative refractive power, its image-side surface is concave at the near optical axis, its image-side surface has at least one convex surface off-axis, its object-side surface and image-side surface are both aspherical, and the third lens is Plastic material. There are three lenses with refractive power in the optical imaging system. The optical imaging system further includes an aperture, and the aperture is disposed between the image-side surface of the first lens and the object-side surface of the second lens. The focal length of the first lens is f1, the focal length of the second lens is f2, the focal length of the third lens is f3, the thickness of the first lens on the optical axis is CT1, the thickness of the third lens on the optical axis is CT3, and the aperture is to The distance on the optical axis from the image side surface of the third lens is SD, and the distance from the object side surface of the first lens to the image side surface of the third lens on the optical axis is TD, which satisfies the following conditions:

|f3|<f2<f1;

1.55<CT1/CT3; and

0.55<SD/TD<0.80.

The present invention further provides an optical imaging system, which sequentially includes a first lens, a second lens and a third lens from the object side to the image side. The first lens has positive refractive power, its object-side surface is convex at the near optical axis, its image-side surface is convex at the near optical axis, its object-side surface and image-side surface are both aspherical, and the first lens is Plastic material. The second lens has positive refractive power, its object-side surface is concave at the near optical axis, its image-side surface is convex at the near optical axis, its object-side surface and image-side surface are both aspherical, and the second lens is Plastic material. The third lens has negative refractive power, its image-side surface is concave at the near optical axis, its image-side surface has at least one convex surface off-axis, its object-side surface and image-side surface are both aspherical, and the third lens is Plastic material. There are three lenses with refractive power in the optical imaging system. The optical imaging system further includes a filter element. At least one of the first lens, the second lens, the third lens and the filter element is made of a material that absorbs visible light. The focal length of the first lens is f1, the focal length of the second lens is f2, the focal length of the third lens is f3, the thickness of the first lens on the optical axis is CT1, and the thickness of the third lens on the optical axis is CT3, which satisfies The following conditions:

|f3|<f2<f1; and

1.25<CT1/CT3.

The present invention further provides an imaging device, which includes the aforementioned optical imaging system and an electronic photosensitive element, wherein the electronic photosensitive element is disposed on the imaging surface of the optical imaging system.

The present invention further provides an electronic device, which includes the aforementioned image capturing device.

When |f3|<f2<f1 satisfies the above conditions, it helps to make the refractive power configuration of the lens in the optical imaging system more balanced, so as to correct the aberration of the optical imaging system and reduce the sensitivity of the optical imaging system.

When CT1/CT3 satisfies the above conditions, the thicknesses of the first lens and the third lens are more appropriate, which contributes to the homogeneity and formability of the lens during manufacture.

When the SD/TD satisfies the above conditions, the optical system design of the optical imaging system can achieve a good balance between telecentric and wide-angle characteristics.

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments, but not as a limitation of the present invention.

Description of drawings

FIG. 1 shows a schematic diagram of an imaging device according to a first embodiment of the present invention;

Fig. 2 is the spherical aberration, astigmatism and distortion curves of the first embodiment in order from left to right;

3 is a schematic diagram of an imaging device according to a second embodiment of the present invention;

Fig. 4 is the spherical aberration, astigmatism and distortion curves of the second embodiment in sequence from left to right;

Fig. 5 is the transmittance spectrum of the third lens of the second embodiment;

Fig. 6 is the transmittance spectrum of the first lens, the second lens and the filter element of the second embodiment;

Fig. 7 is the transmittance spectrum of the optical imaging system of the second embodiment;

8 is a schematic diagram of an imaging device according to a third embodiment of the present invention;

Fig. 9 is the spherical aberration, astigmatism and distortion curves of the third embodiment in sequence from left to right;

10 is a schematic diagram of an imaging device according to a fourth embodiment of the present invention;

Fig. 11 is the spherical aberration, astigmatism and distortion curves of the fourth embodiment in order from left to right;

12 is a schematic diagram of an imaging device according to a fifth embodiment of the present invention;

Fig. 13 is the spherical aberration, astigmatism and distortion curves of the fifth embodiment in order from left to right;

14 is a schematic diagram of an imaging device according to a sixth embodiment of the present invention;

Fig. 15 is the spherical aberration, astigmatism and distortion curves of the sixth embodiment in sequence from left to right;

16 is a schematic diagram of an imaging device according to a seventh embodiment of the present invention;

Fig. 17 is the spherical aberration, astigmatism and distortion curves of the seventh embodiment in order from left to right;

18 is a schematic diagram of an imaging device according to an eighth embodiment of the present invention;

Fig. 19 is the spherical aberration, astigmatism and distortion curves of the eighth embodiment in order from left to right;

FIG. 20 shows a schematic diagram of an electronic device according to the present invention;

FIG. 21 shows a schematic diagram of another electronic device according to the present invention;

FIG. 22 shows a schematic diagram of yet another electronic device according to the present invention;

FIG. 23 is a schematic diagram of yet another electronic device according to the present invention.

Among them, reference signs

Image taking device: 10

Aperture: 100, 200, 300, 400, 500, 600, 700, 800

First lens: 110, 210, 310, 410, 510, 610, 710, 810

Object side surface: 111, 211, 311, 411, 511, 611, 711, 811

Image side surface: 112, 212, 312, 412, 512, 612, 712, 812

Second lens: 120, 220, 320, 420, 520, 620, 720, 820

Object side surface: 121, 221, 321, 421, 521, 621, 721, 821

Image side surface: 122, 222, 322, 422, 522, 622, 722, 822

Third lens: 130, 230, 330, 430, 530, 630, 730, 830

Object side surface: 131, 231, 331, 431, 531, 631, 731, 831

Image side surface: 132, 232, 332, 432, 532, 632, 732, 832

Filter elements: 140, 240, 340, 440, 540, 640, 740, 840

Imaging surface: 150, 250, 350, 450, 550, 650, 750, 850

Electronic photosensitive element: 160, 260, 360, 460, 560, 660, 760, 860

CT1: the thickness of the first lens on the optical axis

CT3: The thickness of the third lens on the optical axis

EPD: Entrance pupil diameter of the optical imaging system

f: focal length of the optical imaging system

f1: focal length of the first lens

f2: focal length of the second lens

f3: focal length of the third lens

Fno: the aperture value of the optical imaging system

HFOV: half of the maximum viewing angle in the optical imaging system

N2: Refractive index of the second lens

N3: Refractive index of the third lens

R2: Radius of curvature of the image-side surface of the first lens

SD: the distance from the aperture to the image side surface of the third lens on the optical axis

T12: the distance between the first lens and the second lens on the optical axis

T23: the distance between the second lens and the third lens on the optical axis

TD: the distance from the object-side surface of the first lens to the image-side surface of the third lens on the optical axis

TL: the distance from the object-side surface of the first lens to the imaging plane on the optical axis

V2: Dispersion coefficient of the second lens

V3: Dispersion coefficient of the third lens

ΣCT: the sum of the lens thicknesses of the first lens, the second lens and the third lens on the optical axis

Detailed ways

Below in conjunction with accompanying drawing, structural principle and working principle of the present invention are specifically described:

The optical imaging system sequentially includes a first lens, a second lens and a third lens from the object side to the image side. Wherein, there are three lenses with refractive power in the optical imaging system.

The first lens has positive refractive power, its object-side surface is convex at the near optical axis, and its image-side surface is convex at the near optical axis. Thereby, the positive refractive force required by the optical imaging system can be provided, and the overall length of the optical imaging system can be properly adjusted. In addition, since both the object-side surface and the image-side surface of the first lens are convex, the curvature distribution of the first lens can be effectively balanced, which helps to avoid the curvature of a single surface of the first lens being too strong, so as to reduce the aberration of the optical imaging system , and reduce the difficulty of molding.

The second lens has positive refractive power, its object side surface is concave at the near optical axis, and its image side surface is convex at the near optical axis. Therefore, both the first lens and the second lens have positive refractive power, which helps to evenly distribute the refractive power of the optical imaging system to reduce the sensitivity of the optical imaging system. In addition, the back focus of the optical imaging system can be effectively reduced to keep the optical imaging system miniaturized.

The third lens has negative refractive power, its object-side surface is concave at the near optical axis, its image-side surface is concave at the near optical axis, and its image-side surface has at least one convex at off-axis. In this way, the first lens, the second lens and the third lens of the optical imaging system form a positive-positive-negative structure, and the refractive power of the third lens is stronger than that of the first lens and the second lens, which can effectively shorten the length of the optical imaging system. The total length of the system and the back focal length. In addition, the incident angle of the off-axis field of view light on the electronic photosensitive element can be suppressed to increase the receiving efficiency of the electronic photosensitive element and further correct the aberration of the off-axis field of view.

The focal length of the first lens is f1, the focal length of the second lens is f2, and the focal length of the third lens is f3, which satisfy the following condition: |f3|<f2<f1. Thereby, it is helpful to make the configuration of the refractive power of the lens in the optical imaging system more balanced, so as to correct the aberration of the optical imaging system and reduce the sensitivity of the optical imaging system.

The thickness of the first lens on the optical axis is CT1, and the thickness of the third lens on the optical axis is CT3, which satisfy the following condition: 1.25<CT1/CT3. Accordingly, the thicknesses of the first lens and the third lens are more appropriate, which contributes to the homogeneity and formability of the lenses during manufacture. Preferably, it satisfies the following condition: 1.55<CT1/CT3. More preferably, it satisfies the following condition: 1.80<CT1/CT3<4.50. Still more preferably, it satisfies the following condition: 2.40<CT1/CT3<3.50.

The optical imaging system further includes an aperture. The distance from the aperture to the image-side surface of the third lens on the optical axis is SD, and the distance from the object-side surface of the first lens to the image-side surface of the third lens on the optical axis is TD, which satisfies the following conditions: 0.55<SD/TD< 0.80. Thereby, the optical system design of the optical imaging system can achieve a good balance between telecentric and wide-angle characteristics.

The distance between the first lens and the second lens on the optical axis is T12, and the distance between the second lens and the third lens on the optical axis is T23, which satisfies the following condition: 2.5<T12/T23. Thereby, the distance between the lenses can be properly adjusted, which helps to shorten the total length of the optical imaging system and maintain its miniaturization.

The sum of the lens thicknesses of the first lens, the second lens, and the third lens on the optical axis is ΣCT (that is, the thickness of the first lens on the optical axis, the thickness of the second lens on the optical axis, and the thickness of the third lens on the optical axis The sum of the thicknesses above), the thickness of the first lens on the optical axis is CT1, which satisfies the following condition: 1.40<ΣCT/CT1<2.60. In this way, the lens can be avoided from being too thin or too thick, which is conducive to maintaining the miniaturization of the optical imaging system and improving the production yield.

The dispersion coefficient of the second lens is V2, and the dispersion coefficient of the third lens is V3, which satisfy the following condition: 0.80<V2/V3<1.33. In this way, the selection of plastic lens materials in the optical imaging system can be more matched, so as to improve the imaging quality of the optical imaging system.

The distance on the optical axis from the object-side surface of the first lens to the image-side surface of the third lens is TD, which satisfies the following condition: TD<2.25mm (mm). Thereby, it is beneficial to miniaturization of the optical imaging system, so as to prevent the optical imaging system from being too bulky, and make the optical imaging system more suitable for use in electronic devices.

The dispersion coefficient of the second lens is V2, and the dispersion coefficient of the third lens is V3, which satisfy the following condition: V2+V3<70. In this way, the selection of plastic lens materials in the optical imaging system can be more matched, so as to improve the imaging quality of the optical imaging system.

The refractive index of the second lens is N2, and the refractive index of the third lens is N3, which satisfy the following condition: 3.00<N2+N3<3.40. Thereby, the refractive indices of the second lens and the third lens are more appropriate, which is beneficial to correct the aberration of the optical imaging system while maintaining good imaging quality.

The distance on the optical axis from the object-side surface of the first lens to the imaging surface is TL, and the entrance pupil diameter of the optical imaging system is EPD, which satisfies the following conditions: 1.0<TL/EPD<3.4. In this way, the amount of light entering the optical imaging system can be increased, which is beneficial to improving the imaging sensitivity under low light source environment.

The focal length of the first lens is f1, the focal length of the second lens is f2, and the focal length of the third lens is f3, which satisfy the following condition: 1.25<(|f3|/f2)+(f2/f1)<1.85. In this way, the configuration of the refractive power of the optical imaging system can be balanced to avoid excessive aberrations, and at the same time, the sensitivity of the optical imaging system can be effectively reduced.

The focal length of the first lens is f1, and the radius of curvature of the image-side surface of the first lens is R2, which satisfies the following condition: -1.5<f1/R2<0. In this way, the curvature of the image-side surface of the first lens is more appropriate, which helps to shorten the total length of the optical imaging system.

The optical imaging system of the present invention can be used in the wavelength range from 750 nanometers (nm) to 1050 nanometers. In this way, light in the infrared wavelength range can be effectively captured to be suitable for various infrared photography applications such as dynamic somatosensory detection, low light source shooting, or iris recognition devices.

The optical imaging system further includes a filter element. At least one of the first lens, the second lens, the third lens and the filter element can be made of a material that absorbs visible light. The visible light absorbing material is, for example, black-dyed plastic. In this way, the optical imaging system can selectively make the lens or filter with visible light absorbing material, so that the lens or filter can effectively reduce the penetration rate of the light source in the visible light band, so as to reduce the impact of the visible light band on the imaging quality.

The configuration of the aperture in the optical imaging system may be a central aperture. The middle aperture means that the aperture is set between the first lens and the imaging surface, which helps to provide a sufficient field of view for the optical imaging system.

In the optical imaging system disclosed in the present invention, the material of the lens can be plastic or glass. When the material of the lens is glass, the degree of freedom in the configuration of the refractive power can be increased. In addition, when the lens is made of plastic, the production cost can be effectively reduced. In addition, an aspheric surface (ASP) can be set on the lens surface. The aspheric surface can be easily made into a shape other than a spherical surface, and more control variables can be obtained to reduce aberrations, thereby reducing the number of lenses required, so it can be effectively Reduce the overall optical length.

In the optical imaging system disclosed in the present invention, if the lens surface is convex and the convex position is not defined, it means that the lens surface is convex at the near optical axis; if the lens surface is concave and the concave position is not defined, then Indicates that the lens surface is concave at the near optical axis. If the refractive power or focal length of the lens does not define its area position, it means that the refractive power or focal length of the lens is the refractive power or focal length of the lens at the near optical axis.

In the optical imaging system disclosed in the present invention, the imaging surface (Image Surface) of the optical imaging system can be a plane or a curved surface with any curvature according to the difference of the corresponding electronic photosensitive element, especially the concave surface facing the object. Surfaces in the lateral direction.

In the optical imaging system disclosed in the present invention, at least one aperture can be provided, and its position can be arranged before the first lens, between each lens or after the last lens. The type of the aperture is such as the flare aperture ( Glare Stop) or field stop (Field Stop), etc., are used to reduce stray light and help improve image quality.

The present invention further provides an imaging device, which includes the aforementioned optical imaging system and an electronic photosensitive element, wherein the electronic photosensitive element is disposed on the imaging surface of the optical imaging system. Preferably, the imaging device may further include a barrel (Barrel Member), a support device (Holder Member) or a combination thereof.

Please refer to FIG. 20, FIG. 21, FIG. 22 and FIG. 23, the imaging device 10 can be applied in many ways to smart phones (as shown in FIG. 20), tablet computers (as shown in FIG. 21), wearable devices (as shown in FIG. 22) and infrared photography device (as shown in Figure 23) etc. Preferably, the electronic device may further include control units (Control Units), display units (DisplayUnits), storage units (Storage Units), temporary storage units (RAM) or combinations thereof.

The optical imaging system of the present invention can be applied to an optical system for moving focusing according to requirements, and has the characteristics of excellent aberration correction and good imaging quality. The present invention can also be applied in various aspects to electronic devices such as three-dimensional (3D) image capture, digital cameras, mobile devices, tablet computers, smart TVs, network monitoring equipment, driving recorders, reversing developing devices, somatosensory game machines, and wearable devices. device. The optical imaging system of the present invention can also be applied to electronic devices that need to be equipped with infrared lenses, such as electronic devices that need to avoid infrared interference, such as dynamic somatosensory detection, low light source shooting, or iris recognition devices. Furthermore, the optical imaging system of the present invention can be used in a wavelength band of 750 nm to 1050 nm, but this range of wavelength is not intended to limit the present invention. The electronic device disclosed above is only an example to illustrate the practical application of the present invention, and does not limit the scope of application of the imaging device of the present invention.

According to the above implementation manners, specific embodiments are proposed below and described in detail with reference to the accompanying drawings.

<First embodiment>

Please refer to FIG. 1 and FIG. 2 , wherein FIG. 1 shows a schematic diagram of an imaging device according to a first embodiment of the present invention, and FIG. 2 is a diagram of spherical aberration, astigmatism and distortion curves of the first embodiment from left to right. As can be seen from FIG. 1 , the imaging device includes an optical imaging system (not otherwise labeled) and an electronic photosensitive element 160 . The optical imaging system includes a first lens 110 , an aperture 100 , a second lens 120 , a third lens 130 , a filter element (Filter) 140 and an imaging surface 150 in sequence from the object side to the image side. Wherein, the electronic photosensitive element 160 is disposed on the imaging surface 150 . There are three lenses (110-130) with refractive power in the optical imaging system.

The first lens 110 has positive refractive power and is made of plastic material. The object-side surface 111 is convex at the near optical axis, and the image-side surface 112 is convex at the near optical axis. Both surfaces are aspherical.

The second lens 120 has positive refractive power and is made of plastic material. The object-side surface 121 is concave at the near optical axis, and the image-side surface 122 is convex at the near optical axis. Both surfaces are aspherical.

The third lens 130 has negative refractive power and is made of plastic material. Its object-side surface 131 is concave at the near optical axis, its image-side surface 132 is concave at the near optical axis, and both surfaces are aspherical. The side surface 132 has at least one convex surface off-axis.

The material of the filter element 140 is glass, which is disposed between the third lens 130 and the imaging surface 150 and does not affect the focal length of the optical imaging system.

The curve equations of the aspheric surfaces of the above-mentioned lenses are expressed as follows:

;in:

X: The point on the aspheric surface whose distance from the optical axis is Y, and its relative distance from the tangent plane tangent to the intersection point on the aspheric optical axis;

Y: The vertical distance between the point on the aspheric curve and the optical axis;

R: radius of curvature;

k: cone coefficient; and

Ai: i-th order aspheric coefficient.

In the optical imaging system of the first embodiment, the focal length of the optical imaging system is f, the aperture value (F-number) of the optical imaging system is Fno, half of the maximum viewing angle in the optical imaging system is HFOV, and its value is as follows : f=2.12mm (mm), Fno=2.85, HFOV=31.3 degrees (deg.).

The refractive index of the second lens 120 is N2, and the refractive index of the third lens 130 is N3, which satisfy the following condition: N2+N3=3.222.

The dispersion coefficient of the second lens 120 is V2, and the dispersion coefficient of the third lens 130 is V3, which satisfy the following condition: V2+V3=53.70.

The dispersion coefficient of the second lens 120 is V2, and the dispersion coefficient of the third lens 130 is V3, which satisfy the following condition: V2/V3=1.29.

The thickness of the first lens 110 on the optical axis is CT1, and the thickness of the third lens 130 on the optical axis is CT3, which satisfy the following condition: CT1/CT3=2.02.

The sum of the lens thicknesses of the first lens 110, the second lens 120 and the third lens 130 on the optical axis is ΣCT, and the thickness of the first lens 110 on the optical axis is CT1, which satisfies the following condition: ΣCT/CT1=2.66.

The distance between the first lens 110 and the second lens 120 on the optical axis is T12, and the distance between the second lens 120 and the third lens 130 on the optical axis is T23, which satisfies the following condition: T12/T23=4.83.

The focal length of the first lens 110 is f1, and the curvature radius of the image-side surface 112 of the first lens is R2, which satisfies the following condition: f1/R2=-0.34.

The focal length of the first lens 110 is f1, the focal length of the second lens 120 is f2, and the focal length of the third lens 130 is f3, which satisfy the following condition: (|f3|/f2)+(f2/f1)=1.41.

The distance on the optical axis from the object-side surface 111 of the first lens to the image-side surface 132 of the third lens is TD, which satisfies the following condition: TD=2.05mm.

The distance on the optical axis from the aperture 100 to the third lens image side surface 132 is SD, and the distance on the optical axis from the first lens object surface 111 to the third lens image side surface 132 is TD, which satisfies the following conditions: SD/ TD = 0.66.

The distance on the optical axis from the object-side surface 111 of the first lens to the imaging surface 150 is TL, and the entrance pupil diameter of the optical imaging system is EPD, which satisfies the following condition: TL/EPD=3.87.

Please refer to Table 1 and Table 2 below.

Table 1 shows detailed structural data of the first embodiment in FIG. 1 , where the units of the radius of curvature, thickness and focal length are millimeters (mm), and surfaces 0 to 10 represent surfaces from the object side to the image side in sequence. Table 2 shows the aspheric surface data in the first embodiment, where k is the cone coefficient in the aspheric curve equation, and A4 to A16 represent the 4th to 16th order aspheric coefficients of each surface. In addition, the tables of the following embodiments are schematic diagrams and aberration curve diagrams corresponding to the respective embodiments, and the definitions of the data in the tables are the same as those in Table 1 and Table 2 of the first embodiment, and will not be repeated here.

<Second Embodiment>

Please refer to FIG. 3 and FIG. 4 , wherein FIG. 3 shows a schematic diagram of an imaging device according to a second embodiment of the present invention, and FIG. 4 is a diagram of spherical aberration, astigmatism and distortion curves of the second embodiment from left to right. As can be seen from FIG. 3 , the imaging device includes an optical imaging system (not otherwise labeled) and an electronic photosensitive element 260 . The optical imaging system includes a first lens 210 , an aperture 200 , a second lens 220 , a third lens 230 , a filter element 240 and an imaging surface 250 in order from the object side to the image side. Wherein, the electronic photosensitive element 260 is disposed on the imaging surface 250 . There are three lenses (210-230) with refractive power in the optical imaging system.

The first lens 210 has positive refractive power and is made of plastic material. The object-side surface 211 is convex at the near optical axis, and the image-side surface 212 is convex at the near optical axis. Both surfaces are aspherical.

The second lens 220 has positive refractive power and is made of plastic material. The object-side surface 221 is concave at the near optical axis, and the image-side surface 222 is convex at the near optical axis. Both surfaces are aspherical.

The third lens 230 has negative refractive power and is made of plastic material. Its object side surface 231 is concave at the near optical axis, and its image side surface 232 is concave at the near optical axis. Both surfaces are aspherical. The side surface 232 has at least one convex surface off-axis.

The material of the filter element 240 is glass, which is disposed between the third lens 230 and the imaging surface 250 and does not affect the focal length of the optical imaging system.

In the second embodiment, the third lens 230 is made of a material that absorbs visible light, and the first lens 210 , the second lens 220 and the filter element 240 are made of a material that does not absorb visible light. In this way, the third lens 230 can effectively reduce the transmittance of the light source in the visible light band. Furthermore, in the second embodiment, the third lens 230 made of a visible light absorbing material can absorb the wavelength band of 400nm-700nm (ie, the visible light band), so that the transmittance of the visible light band is lower than 50%. Accordingly, the optical imaging system is suitable for a wavelength band of about 810nm. Please refer to Figure 5, Figure 6 and Figure 7. FIG. 5 is the transmittance spectrum of the third lens of the second embodiment. Fig. 6 is the transmittance of the first lens, the second lens and the filter element of the second embodiment

spectrum. FIG. 7 is a transmittance spectrum of the optical imaging system of the second embodiment.

Please refer to Table 3 and Table 4 below.

In the second embodiment, the curve equation of the aspheric surface is expressed in the form of the first embodiment. In addition, the definitions described in the table below are the same as those in the first embodiment, and will not be repeated here.

<Third embodiment>

Please refer to FIG. 8 and FIG. 9 , wherein FIG. 8 shows a schematic diagram of an imaging device according to a third embodiment of the present invention, and FIG. 9 is a diagram of spherical aberration, astigmatism and distortion curves of the third embodiment in order from left to right. As can be seen from FIG. 8 , the imaging device includes an optical imaging system (not otherwise labeled) and an electronic photosensitive element 360 . The optical imaging system includes a first lens 310 , an aperture 300 , a second lens 320 , a third lens 330 , a filter element 340 and an imaging surface 350 in order from the object side to the image side. Wherein, the electronic photosensitive element 360 is disposed on the imaging surface 350 . There are three lenses (310-330) with refractive power in the optical imaging system.

The first lens 310 has positive refractive power and is made of plastic material. The object-side surface 311 is convex at the near optical axis, and the image-side surface 312 is convex at the near optical axis. Both surfaces are aspherical.

The second lens 320 has positive refractive power and is made of plastic material. The object-side surface 321 is concave at the near optical axis, and the image-side surface 322 is convex at the near optical axis. Both surfaces are aspherical.

The third lens 330 has negative refractive power and is made of plastic material. Its object-side surface 331 is convex at the near optical axis, and its image-side surface 332 is concave at the near optical axis. Both surfaces are aspherical. The side surface 332 has at least one convex surface off-axis.

The material of the filter element 340 is glass, which is disposed between the third lens 330 and the imaging surface 350 and does not affect the focal length of the optical imaging system.

Please refer to Table 5 and Table 6 below.

In the third embodiment, the curve equation of the aspheric surface is expressed in the form of the first embodiment. In addition, the definitions described in the table below are the same as those in the first embodiment, and will not be repeated here.

<Fourth Embodiment>

Please refer to FIG. 10 and FIG. 11 , wherein FIG. 10 shows a schematic diagram of an imaging device according to a fourth embodiment of the present invention, and FIG. 11 is a diagram of spherical aberration, astigmatism and distortion curves of the fourth embodiment from left to right. As can be seen from FIG. 10 , the imaging device includes an optical imaging system (not otherwise labeled) and an electronic photosensitive element 460 . The optical imaging system includes a first lens 410 , an aperture 400 , a second lens 420 , a third lens 430 , a filter element 440 and an imaging surface 450 sequentially from the object side to the image side. Wherein, the electronic photosensitive element 460 is disposed on the imaging surface 450 . There are three lenses (410-430) with refractive power in the optical imaging system.

The first lens 410 has positive refractive power and is made of plastic material. The object-side surface 411 is convex at the near optical axis, and the image-side surface 412 is convex at the near optical axis. Both surfaces are aspherical.

The second lens 420 has positive refractive power and is made of plastic material. The object-side surface 421 is concave at the near optical axis, and the image-side surface 422 is convex at the near optical axis. Both surfaces are aspherical.

The third lens 430 has negative refractive power and is made of plastic material. Its object side surface 431 is concave at the near optical axis, its image side surface 432 is concave at the near optical axis, and both surfaces are aspherical. The side surface 432 has at least one convex surface off-axis.

The material of the filter element 440 is glass, which is disposed between the third lens 430 and the imaging surface 450 and does not affect the focal length of the optical imaging system.

Please refer to Table 7 and Table 8 below.

In the fourth embodiment, the curve equation of the aspheric surface is expressed in the form of the first embodiment. In addition, the definitions described in the table below are the same as those in the first embodiment, and will not be repeated here.

<Fifth Embodiment>

Please refer to FIG. 12 and FIG. 13 , wherein FIG. 12 shows a schematic diagram of an imaging device according to a fifth embodiment of the present invention, and FIG. 13 is a diagram of spherical aberration, astigmatism and distortion curves of the fifth embodiment in order from left to right. As can be seen from FIG. 12 , the imaging device includes an optical imaging system (not otherwise labeled) and an electronic photosensitive element 560 . The optical imaging system includes a first lens 510 , an aperture 500 , a second lens 520 , a third lens 530 , a filter element 540 and an imaging surface 550 in order from the object side to the image side. Wherein, the electronic photosensitive element 560 is disposed on the imaging surface 550 . There are three lenses (510-530) with refractive power in the optical imaging system.

The first lens 510 has positive refractive power and is made of plastic material. The object-side surface 511 is convex at the near optical axis, and the image-side surface 512 is convex at the near optical axis. Both surfaces are aspherical.

The second lens 520 has positive refractive power and is made of plastic material. The object-side surface 521 is concave at the near optical axis, and the image-side surface 522 is convex at the near optical axis. Both surfaces are aspherical.

The third lens 530 has negative refractive power and is made of plastic material. Its object-side surface 531 is convex at the near optical axis, its image-side surface 532 is concave at the near optical axis, and both surfaces are aspherical. The side surface 532 has at least one convex surface off-axis.

The material of the filter element 540 is glass, which is disposed between the third lens 530 and the imaging surface 550 and does not affect the focal length of the optical imaging system.

In the fifth embodiment, the first lens 510 is made of a material that absorbs visible light, and the second lens 520 , the third lens 530 and the filter element 540 are made of a material that does not absorb visible light. In this way, the first lens 510 can absorb the wavelength band of 400nm-700nm (that is, the visible light band), so that the optical imaging system is suitable for the wavelength band of about 810nm.

Please refer to Table 9 and Table 10 below.

In the fifth embodiment, the curve equation of the aspheric surface is expressed in the form of the first embodiment. In addition, the definitions described in the table below are the same as those in the first embodiment, and will not be repeated here.

<Sixth Embodiment>

Please refer to FIG. 14 and FIG. 15 , wherein FIG. 14 shows a schematic diagram of an imaging device according to a sixth embodiment of the present invention, and FIG. 15 is a diagram of spherical aberration, astigmatism and distortion curves of the sixth embodiment from left to right. It can be seen from FIG. 14 that the imaging device includes an optical imaging system (not otherwise labeled) and an electronic photosensitive element 660 . The optical imaging system includes a first lens 610 , an aperture 600 , a second lens 620 , a third lens 630 , a filter element 640 and an imaging surface 650 in sequence from the object side to the image side. Wherein, the electronic photosensitive element 660 is disposed on the imaging surface 650 . There are three lenses (610-630) with refractive power in the optical imaging system.

The first lens 610 has positive refractive power and is made of plastic material. The object-side surface 611 is convex at the near optical axis, and the image-side surface 612 is convex at the near optical axis. Both surfaces are aspherical.

The second lens 620 has positive refractive power and is made of plastic material. The object-side surface 621 is concave at the near optical axis, and the image-side surface 622 is convex at the near optical axis. Both surfaces are aspherical.

The third lens 630 has negative refractive power and is made of plastic material. Its object-side surface 631 is convex at the near optical axis, and its image-side surface 632 is concave at the near optical axis. Both surfaces are aspherical. The surface 632 has at least one convexity off-axis.

The material of the filter element 640 is glass, which is disposed between the third lens 630 and the imaging surface 650 and does not affect the focal length of the optical imaging system.

In the sixth embodiment, the first lens 610 is made of a material that absorbs visible light, and the second lens 620 , the third lens 630 and the filter element 640 are made of a material that does not absorb visible light. In this way, the first lens 610 can absorb the wavelength band of 400nm-700nm (that is, the visible light band), so that the optical imaging system is suitable for the wavelength band of about 810nm.

Please refer to Table 11 and Table 12 below.

In the sixth embodiment, the curve equation of the aspheric surface is expressed in the form of the first embodiment. In addition, the definitions described in the table below are the same as those in the first embodiment, and will not be repeated here.

<Seventh Embodiment>

Please refer to FIG. 16 and FIG. 17 , wherein FIG. 16 shows a schematic diagram of an imaging device according to a seventh embodiment of the present invention, and FIG. 17 is a diagram of spherical aberration, astigmatism and distortion curves of the seventh embodiment in sequence from left to right. It can be seen from FIG. 16 that the imaging device includes an optical imaging system (not otherwise labeled) and an electronic photosensitive element 760 . The optical imaging system includes a first lens 710 , an aperture 700 , a second lens 720 , a third lens 730 , a filter element 740 and an imaging surface 750 in order from the object side to the image side. Wherein, the electronic photosensitive element 760 is disposed on the imaging surface 750 . There are three lenses (710-730) with refractive power in the optical imaging system.

The first lens 710 has positive refractive power and is made of plastic material. The object-side surface 711 is convex at the near optical axis, and the image-side surface 712 is convex at the near optical axis. Both surfaces are aspherical.

The second lens 720 has positive refractive power and is made of plastic material. The object-side surface 721 is concave at the near optical axis, and the image-side surface 722 is convex at the near optical axis. Both surfaces are aspherical.

The third lens 730 has negative refractive power and is made of plastic material. Its object-side surface 731 is convex at the near optical axis, its image-side surface 732 is concave at the near optical axis, and both surfaces are aspherical. The side surface 732 has at least one convex surface off-axis.

The material of the filter element 740 is glass, which is disposed between the third lens 730 and the imaging surface 750 and does not affect the focal length of the optical imaging system.

In the seventh embodiment, the second lens 720 is made of a material that absorbs visible light, and the first lens 710 , the third lens 730 and the filter element 740 are made of a material that does not absorb visible light. In this way, the second lens 720 can absorb the wavelength band of 400nm-700nm (that is, the visible light band), so that the optical imaging system is suitable for the wavelength band of about 810nm.

Please refer to Table 13 and Table 14 below.

In the seventh embodiment, the curve equation of the aspheric surface is expressed in the form of the first embodiment. In addition, the definitions described in the table below are the same as those in the first embodiment, and will not be repeated here.

<Eighth embodiment>

Please refer to FIG. 18 and FIG. 19 , wherein FIG. 18 shows a schematic diagram of an imaging device according to an eighth embodiment of the present invention, and FIG. 19 is a graph of spherical aberration, astigmatism and distortion of the eighth embodiment from left to right. As can be seen from FIG. 18 , the imaging device includes an optical imaging system (not otherwise labeled) and an electronic photosensitive element 860 . The optical imaging system includes a first lens 810 , an aperture 800 , a second lens 820 , a third lens 830 , a filter element 840 and an imaging surface 850 in order from the object side to the image side. Wherein, the electronic photosensitive element 860 is disposed on the imaging surface 850 . There are three lenses (810-830) with refractive power in the optical imaging system.

The first lens 810 has positive refractive power and is made of plastic material. The object-side surface 811 is convex at the near optical axis, and the image-side surface 812 is convex at the near optical axis. Both surfaces are aspherical.

The second lens 820 has positive refractive power and is made of plastic material. The object-side surface 821 is concave at the near optical axis, and the image-side surface 822 is convex at the near optical axis. Both surfaces are aspherical.

The third lens 830 has negative refractive power and is made of plastic material. Its object-side surface 831 is convex at the near optical axis, and its image-side surface 832 is concave at the near optical axis. Both surfaces are aspherical. The side surface 832 has at least one convex surface off-axis.

The material of the filter element 840 is plastic, and it is disposed between the third lens 830 and the imaging surface 850 without affecting the focal length of the optical imaging system.

In the eighth embodiment, the filter element 840 is made of a material that absorbs visible light, and the first lens 810 , the second lens 820 and the third lens 830 are made of a material that does not absorb visible light. In this way, the filter element 840 can absorb the wavelength band of 400nm-700nm (that is, the visible light band), so that the optical imaging system is suitable for the wavelength band of about 810nm.

Please refer to Table 15 and Table 16 below.

In the eighth embodiment, the curve equation of the aspheric surface is expressed in the form of the first embodiment. In addition, the definitions described in the table below are the same as those in the first embodiment, and will not be repeated here.

The above-mentioned image capturing device can be installed in an electronic device. The present invention uses an optical imaging system with three lenses with refractive power, wherein the optical imaging system includes a first lens with positive refractive power, a second lens with positive refractive power and a third lens with negative refractive power, and the first lens The refractive power of the three lenses is stronger than that of the first lens and the second lens. Thereby, the total length and back focus of the optical imaging system can be effectively shortened. In addition, when specific conditions are met, it is helpful to make the refractive power configuration of the lens in the optical imaging system more balanced, so as to correct the aberration of the optical imaging system and reduce the sensitivity of the optical imaging system. Furthermore, both the object-side surface and the image-side surface of the first lens are convex, which can effectively balance the curvature distribution of the first lens and help avoid the curvature of a single surface of the first lens being too strong, so as to reduce the generation of aberrations in the optical imaging system , and reduce the difficulty of molding.

Although the present invention has been disclosed above with the embodiments, it is not intended to limit the present invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be determined by the scope defined by the appended claims.

Claims (24)

1. An optical imaging system, characterized in that it comprises sequentially from the object side to the image side: A first lens with positive refractive power, its object-side surface is convex at the near optical axis, its image-side surface is convex at the near optical axis, its object-side surface and image-side surface are both aspherical, and the first A lens is made of plastic material; A second lens with positive refractive power, its object-side surface is concave at the near optical axis, its image-side surface is convex at the near optical axis, both its object-side surface and image-side surface are aspherical, and the first The second lens is made of plastic material; and A third lens has negative refractive power, its image-side surface is concave at the near optical axis, its image-side surface has at least one convex surface off-axis, its object-side surface and image-side surface are both aspherical, and the first The three lenses are made of plastic material; Wherein, the lenses with refractive power in the optical imaging system are the first lens, the second lens and the third lens, and the optical imaging system further includes an aperture, and the aperture is arranged on the image side of the first lens surface and the object-side surface of the second lens; Wherein, the focal length of the first lens is f1, the focal length of the second lens is f2, the focal length of the third lens is f3, the thickness of the first lens on the optical axis is CT1, and the thickness of the third lens on the optical axis The thickness is CT3, the distance from the aperture to the image-side surface of the third lens on the optical axis is SD, the distance from the object-side surface of the first lens to the image-side surface of the third lens on the optical axis is TD, the first lens The refractive index of the second lens is N2, and the refractive index of the third lens is N3, which satisfy the following conditions: |f3|<f2<f1; 1.55<CT1/CT3; 0.55<SD/TD<0.80; and 3.00<N2+N3<3.40. 2. The optical imaging system according to claim 1, wherein the distance between the first lens and the second lens on the optical axis is T12, and the second lens and the third lens are on the optical axis The separation distance is T23, which satisfies the following conditions: 2.5<T12/T23. 3. The optical imaging system according to claim 2, wherein the thickness of the first lens on the optical axis is CT1, and the thickness of the third lens on the optical axis is CT3, which satisfy the following conditions: 1.80<CT1/CT3<4.50. 4. The optical imaging system according to claim 2, wherein the sum of the lens thicknesses of the first lens, the second lens and the third lens on the optical axis is ΣCT, and the first lens is ΣCT on the optical axis The thickness on is CT1, which satisfies the following conditions: 1.40<ΣCT/CT1<2.60. 5. The optical imaging system according to claim 1, wherein the thickness of the first lens on the optical axis is CT1, and the thickness of the third lens on the optical axis is CT3, which satisfy the following conditions: 2.40<CT1/CT3<3.50. 6 . The optical imaging system according to claim 1 , wherein the object-side surface of the third lens is concave at the near optical axis. 7. The optical imaging system according to claim 1, wherein the dispersion coefficient of the second lens is V2, and the dispersion coefficient of the third lens is V3, which satisfy the following conditions: 0.80<V2/V3<1.33. 8. The optical imaging system according to claim 1, wherein the distance on the optical axis from the object-side surface of the first lens to the image-side surface of the third lens is TD, which satisfies the following conditions: TD<2.25mm. 9. The optical imaging system according to claim 1, wherein the dispersion coefficient of the second lens is V2, and the dispersion coefficient of the third lens is V3, which satisfy the following conditions: V2+V3<70. 10. The optical imaging system according to claim 1, wherein the distance from the object-side surface of the first lens to an imaging plane on the optical axis is TL, the entrance pupil diameter of the optical imaging system is EPD, It satisfies the following conditions: 1.0<TL/EPD<3.4. 11. The optical imaging system according to claim 1, wherein the focal length of the first lens is f1, the focal length of the second lens is f2, and the focal length of the third lens is f3, which satisfy the following conditions: 1.25<(|f3|/f2)+(f2/f1)<1.85. 12. The optical imaging system according to claim 11, wherein the focal length of the first lens is f1, and the radius of curvature of the image-side surface of the first lens is R2, which satisfies the following conditions: -1.5<f1/R2<0. 13 . The optical imaging system according to claim 1 , wherein the optical imaging system is used in a wavelength range from 750 nm to 1050 nm. 14 . 14. The optical imaging system according to claim 1, further comprising a filter element, wherein at least one of the first lens, the second lens, the third lens and the filter element is Made of materials that absorb visible light. 15. An imaging device, characterized in that it comprises: The optical imaging system according to claim 1; and An electronic photosensitive element, wherein the electronic photosensitive element is arranged on an imaging surface of the optical imaging system. 16. An electronic device, characterized in that it comprises: The imaging device as claimed in claim 15. 17. An optical imaging system, characterized in that it includes sequentially from the object side to the image side: A first lens with positive refractive power, its object-side surface is convex at the near optical axis, its image-side surface is convex at the near optical axis, both its object-side surface and image-side surface are aspheric, and the first lens A lens is made of plastic material; A second lens with positive refractive power, its object-side surface is concave at the near optical axis, its image-side surface is convex at the near optical axis, both its object-side surface and image-side surface are aspherical, and the first The second lens is made of plastic material; and A third lens has negative refractive power, its image-side surface is concave at the near optical axis, its image-side surface has at least one convex surface off-axis, its object-side surface and image-side surface are both aspherical, and the first The three lenses are made of plastic material; Wherein, the lenses with refractive power in the optical imaging system are the first lens, the second lens and the third lens, the optical imaging system further includes a filter element, and the first lens, the second At least one of the lens, the third lens and the filter element is made of a material that absorbs visible light; Wherein, the focal length of the first lens is f1, the focal length of the second lens is f2, the focal length of the third lens is f3, the thickness of the first lens on the optical axis is CT1, and the thickness of the third lens on the optical axis The thickness is CT3, the refractive index of the second lens is N2, and the refractive index of the third lens is N3, which satisfy the following conditions: |f3|<f2<f1; 1.25<CT1/CT3; and 3.00<N2+N3<3.40. 18. The optical imaging system according to claim 17, wherein the thickness of the first lens on the optical axis is CT1, and the thickness of the third lens on the optical axis is CT3, which satisfy the following conditions: 1.55<CT1/CT3. 19. The optical imaging system according to claim 17, wherein the distance from the object-side surface of the first lens to the image-side surface of the third lens on the optical axis is TD, which satisfies the following conditions: TD<2.25mm. 20. The optical imaging system according to claim 17, wherein the dispersion coefficient of the second lens is V2, and the dispersion coefficient of the third lens is V3, which satisfy the following conditions: V2+V3<70. 21. The optical imaging system according to claim 17, wherein the distance from the object-side surface of the first lens to an imaging plane on the optical axis is TL, the entrance pupil diameter of the optical imaging system is EPD, It satisfies the following conditions: 1.0<TL/EPD<3.4. 22. The optical imaging system according to claim 17, wherein the sum of the lens thicknesses of the first lens, the second lens, and the third lens on the optical axis is ΣCT, and the first lens is ΣCT on the optical axis The thickness on is CT1, which satisfies the following conditions: 1.40<ΣCT/CT1<2.60. 23. An imaging device, characterized in that it comprises: The optical imaging system of claim 17; and An electronic photosensitive element, wherein the electronic photosensitive element is arranged on an imaging surface of the optical imaging system. 24. An electronic device, characterized in that it comprises: The imaging device as claimed in claim 23.