TWI689747B - Four-piece dual waveband optical lens system - Google Patents

Abstract

A four-piece dual waveband optical lens system includes, in order from the object side to the image side: a stop; a first lens element with a positive refractive power having an object-side surface being convex near an optical axis and an image-side surface being convex near the optical axis; a second lens element with a negative refractive power having an object-side surface being concave near the optical axis and an image-side surface being convex near the optical axis; a third lens element with a positive refractive power having an object-side surface being concave near the optical axis and an image-side surface being convex near the optical axis; a fourth lens element with a negative refractive power having an object-side surface being convex near the optical axis and an image-side surface being concave near the optical axis. Such a system has a short length and good performance without re-focusing when used in both visible and infrared wavebands.

Description

Four-piece dual-band imaging lens set

The invention relates to a four-piece dual-band imaging lens group, in particular to a miniaturized four-piece dual-band imaging lens group applied to electronic products.

With the development of high-standard mobile devices such as smartphones and tablets, high-quality small photographic lenses are standard equipment, and with the popularity of the Internet community, more and more people like to take pictures or take selfies with others Sharing, such as game consoles, driving recorders, security camera lenses, etc., the demand for shooting angle is also increasing, so the requirements for lens shooting angle and image quality are becoming more and more strict.

In addition, most of the existing visible light and infrared dual-band zoom systems are composed of two separate systems. Not only is the system bulky, but the overall structure is complex. In addition, when the external environment changes, such as the target is blocked, disguised, smoke interference, and day and night, and the light path and band conversion, the target needs to be searched again to observe the target, that is, under the visible and infrared dual band use , The focus must be readjusted to make the image quality better.

The purpose of the present invention is to provide a four-piece dual-band imaging lens set, in particular a short lens length, and when used in both visible and infrared dual-band, without refocusing, both have good performance. Chip dual-band imaging lens set.

In order to achieve the foregoing objective, a four-piece dual-band imaging lens set according to the present invention includes an aperture and an optical group composed of four lenses, from the object side to the image side in order: the aperture; one The first lens has a positive refractive power, the object-side surface of the first lens is convex near the optical axis, the image-side surface of the first lens is convex near the optical axis, and the object-side surface and image side of the first lens At least one surface is aspheric; a second lens has negative refractive power, the object-side surface of the second lens is concave near the optical axis, and the image-side surface of the second lens is convex near the optical axis, the first At least one of the object-side surface and the image-side surface of the two lenses is aspheric; a third lens has a positive refractive power, the object-side surface of the third lens is concave near the optical axis, and the image-side surface of the third lens The near-optical axis is convex, at least one of the object-side surface and the image-side surface of the third lens is aspherical; and a fourth lens has negative refractive power, and the fourth-side object-side surface of the fourth lens is near the optical axis A convex surface, the image-side surface of the fourth lens is concave near the optical axis, and at least one of the object-side surface and the image-side surface of the fourth lens is aspherical.

Preferably, the focal length of the first lens is f1, and the focal length of the second lens is f2, and the following conditions are satisfied: -0.8 <f1/f2 <-0.4. In this way, the configuration of the refractive power of the first lens and the second lens is more appropriate to reduce the excessive increase of the system aberration.

Preferably, the focal length of the second lens is f2, and the focal length of the third lens is f3, and the following conditions are satisfied: -1.6 <f2/f3 <-0.9. In this way, the peripheral resolution and illuminance of the system can be improved.

Preferably, the focal length of the third lens is f3, and the focal length of the fourth lens is f4, and the following conditions are satisfied: -0.8 <f3/f4 <-0.3. In this way, the system's bending force configuration can be effectively balanced, which helps to reduce sensitivity and improve manufacturing yield.

Preferably, the focal length of the first lens is f1, and the focal length of the third lens is f3, and the following conditions are satisfied: 0.6 <f1/f3 <1.0. In this way, the positive refractive power of the first lens is effectively distributed to reduce the sensitivity of the four-piece dual-band imaging lens group.

Preferably, the focal length of the second lens is f2, and the focal length of the fourth lens is f4, and the following conditions are satisfied: 0.3 <f2/f4 <1.2. In this way, the positive refractive power distribution of the system is more appropriate, which is helpful to correct the system aberration to improve the imaging quality of the system.

Preferably, wherein the focal length of the first lens is f1, the combined focal length of the second lens and the third lens is f23, and the following conditions are satisfied: 0.1 <f1/f23 <0.7. In this way, the resolution capability of the four-piece dual-band imaging lens group is improved.

Preferably, the combined focal length of the second lens and the third lens is f23, and the focal length of the fourth lens is f4, and the following conditions are satisfied: -1.6 <f23/f4 <-0.9. This can effectively correct the curvature of field.

Preferably, the combined focal length of the first lens and the second lens is f12, and the combined focal length of the third lens and the fourth lens is f34, and the following conditions are satisfied: 0.7 <f12/f34 <1.5. This can effectively correct the curvature of field.

Preferably, wherein the overall focal length of the four-piece dual-band imaging lens group is f, the distance from the object-side surface of the first lens to the imaging plane on the optical axis is TL, and the following conditions are satisfied: 0.5 <f/TL <0.8. In this way, it can be beneficial to maintain the miniaturization of the four-piece dual-band imaging lens group to be mounted on thin and light electronic products.

Preferably, the radius of curvature of the object-side surface of the first lens is R1, and the radius of curvature of the image-side surface of the first lens is R2, and the following conditions are satisfied: -2.1 <R1/R2 <-0.4. In this way, the first lens can have an appropriate surface shape to reduce the generation of astigmatism.

Preferably, the radius of curvature of the object-side surface of the third lens is R5, and the radius of curvature of the image-side surface of the third lens is R6, and the following conditions are satisfied: 4<R5/R6<14. This provides sufficient freedom for the peripheral shape of the third lens to correct off-axis aberrations and maintain relative illuminance around the imaging surface.

Preferably, the radius of curvature of the object-side surface of the fourth lens is R7, and the radius of curvature of the image-side surface of the fourth lens is R8, and the following conditions are satisfied: 1.3 <R7/R8 <2.1. This provides sufficient freedom for the peripheral shape of the fourth lens to correct off-axis aberrations and increase the area of the imaging surface.

Preferably, the thickness of the second lens on the optical axis is CT2, and the thickness of the first lens on the optical axis is CT1, and the following conditions are satisfied: 0.3 <CT2/CT1 <0.7. In this way, the thickness of the first lens and the second lens is not too large or too small, which is beneficial to the assembly and arrangement of the lenses.

Regarding the technology, means and other effects adopted by the present invention to achieve the above-mentioned objectives, seven preferred feasible embodiments are described in detail below with reference to the drawings.

<First embodiment>

Please refer to FIGS. 1A and 1B, wherein FIG. 1A shows a schematic diagram of a four-piece dual-band imaging lens set according to the first embodiment of the present invention, and FIG. Curved and distorted aberration curves of the imaging band of the band imaging lens group. As can be seen from FIG. 1A, the four-piece dual-band imaging lens group includes an aperture 100 and an optical group. The optical group includes a first lens 110, a second lens 120, and a third lens 130 in order from the object side to the image side. The fourth lens 140, the infrared filter element 170, and the imaging surface 180, wherein the four-piece dual-band imaging lens group has four refractive lenses. The aperture 100 is disposed before the first lens 110.

The first lens 110 has a positive refractive power and is made of plastic material. The object-side surface 111 is convex near the optical axis 190, the image-side surface 112 is convex near the optical axis 190, and the object-side surface 111 and the image side The surfaces 112 are all aspherical.

The second lens 120 has a negative refractive power and is made of plastic material. The object-side surface 121 is concave near the optical axis 190, the image-side surface 122 is convex near the optical axis 190, and the object-side surface 121 and the image side The surfaces 122 are all aspherical.

The third lens 130 has a positive refractive power and is made of plastic. The object-side surface 131 is concave near the optical axis 190, the image-side surface 132 is convex near the optical axis 190, and the object-side surface 131 and the image side The surfaces 132 are all aspherical.

The fourth lens 140 has negative refractive power and is made of plastic material. The object-side surface 141 is convex near the optical axis 190, the image-side surface 142 is concave near the optical axis 190, and the object-side surface 141 and the image side The surfaces 142 are all aspherical, and the object-side surface 141 and the image-side surface 142 have at least one inflection point away from the optical axis 190.

The infrared filter element 170 is made of glass, which is disposed between the fourth lens 140 and the imaging surface 180 and does not affect the focal length of the four-piece dual-band imaging lens group.

上述各透鏡的非球面的曲線方程式表示如下：

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

Where z is the position value along the optical axis 190 at the height h with the surface vertex as a reference; c is the curvature of the lens surface close to the optical axis 190 and is the reciprocal of the radius of curvature (R) (c=1/R) , R is the radius of curvature of the lens surface near the optical axis 190, h is the vertical distance of the lens surface from the optical axis 190, k is the conic constant, and A, B, C, D, E, F, ... are Higher-order aspheric coefficients.

In the four-piece dual-band imaging lens group of the first embodiment, the focal length of the four-piece dual-band imaging lens group is f, and the f-number of the four-piece dual-band imaging lens group is Fno, and the four-piece type The maximum field angle (drawing angle) in the dual-band imaging lens group is FOV, and the values are as follows: f=1.04 (mm); Fno=2.07; and FOV=75.69 (degrees).

In the four-piece dual-band imaging lens group of the first embodiment, the focal length of the first lens 110 is f1, and the focal length of the second lens 120 is f2, and the following conditions are satisfied: f1/f2 = -0.620.

In the four-piece dual-band imaging lens group of the first embodiment, the focal length of the second lens 120 is f2, and the focal length of the third lens 130 is f3, and the following conditions are satisfied: f2/f3 = -1.324.

In the four-piece dual-band imaging lens group of the first embodiment, the focal length of the third lens 130 is f3, and the focal length of the fourth lens 140 is f4, and the following conditions are satisfied: f3/f4 = -0.675.

In the four-piece dual-band imaging lens group of the first embodiment, the focal length of the first lens 110 is f1, and the focal length of the third lens 130 is f3, and the following conditions are satisfied: f1/f3 = 0.822.

In the four-piece dual-band imaging lens group of the first embodiment, the focal length of the second lens 120 is f2, and the focal length of the fourth lens 140 is f4, and the following conditions are satisfied: f2/f4 = 0.894.

In the four-piece dual-band imaging lens group of the first embodiment, the focal length of the first lens 110 is f1, the combined focal length of the second lens 120 and the third lens 130 is f23, and the following conditions are satisfied: f1/f23 = 0.458.

In the four-piece dual-band imaging lens group of the first embodiment, the combined focal length of the second lens 120 and the third lens 130 is f23, and the focal length of the fourth lens 140 is f4, and the following conditions are satisfied: f23/f4 = -1.210.

In the four-piece dual-band imaging lens group of the first embodiment, the combined focal length of the first lens 110 and the second lens 120 is f12, and the combined focal length of the third lens 130 and the fourth lens 140 is f34, and satisfies the following Condition: f12/f34 = 0.962.

In the four-piece dual-band imaging lens group of the first embodiment, the overall focal length of the four-piece dual-band imaging lens group is f, and the object-side surface 111 of the first lens 110 to the imaging plane 180 on the optical axis 190 The distance is TL and meets the following conditions: f/TL = 0.679.

In the four-piece dual-band imaging lens group of the first embodiment, the radius of curvature of the object-side surface 111 of the first lens 110 is R1, and the radius of curvature of the image-side surface 112 of the first lens 110 is R2, and the following conditions are satisfied: R1/R2 = -0.857.

In the four-piece dual-band imaging lens group of the first embodiment, the radius of curvature of the object-side surface 131 of the third lens 130 is R5, and the radius of curvature of the image-side surface 132 of the third lens 130 is R6, and the following conditions are satisfied: R5/R6 = 11.106.

In the four-piece dual-band imaging lens group of the first embodiment, the radius of curvature of the object-side surface 141 of the fourth lens 140 is R7, and the radius of curvature of the image-side surface 142 of the fourth lens 140 is R8, and the following conditions are satisfied: R7/R8 = 1.834.

In the four-piece dual-band imaging lens set of the first embodiment, the thickness of the second lens 120 on the optical axis 190 is CT2, and the thickness of the first lens 110 on the optical axis 190 is CT1, and the following conditions are satisfied: CT2/CT1 = 0.545.

Refer to Table 1 and Table 2 below.

Table 1 is the detailed structural data of the first embodiment of FIG. 1A, in which the units of radius of curvature, thickness and focal length are mm, and surfaces 0-12 sequentially represent the surfaces from the object side to the image side. Table 2 is the aspheric surface data in the first embodiment, wherein k represents the conical surface coefficient in the aspheric surface curve equation, and A, B, C, D, E, F, G... are high-order aspheric surface coefficients. In addition, the following table of each embodiment is a schematic diagram corresponding to each embodiment and a curve curve of image plane distortion and distortion. The definitions of the data in the table are the same as the definitions of Table 1 and Table 2 of the first embodiment. Add details.

<Second embodiment>

Please refer to FIG. 2A and FIG. 2B, wherein FIG. 2A shows a schematic diagram of a four-piece dual-band imaging lens set according to a second embodiment of the present invention, and FIG. Curved and distorted aberration curves of the imaging band of the band imaging lens group. As can be seen from FIG. 2A, the four-piece dual-band imaging lens group includes an aperture 200 and an optical group, which sequentially includes a first lens 210, a second lens 220, and a third lens 230 from the object side to the image side. The fourth lens 240, the infrared filter element 270, and the imaging surface 280, wherein the four-piece dual-band imaging lens group has four refractive lenses. The aperture 200 is disposed before the first lens 210.

The first lens 210 has a positive refractive power and is made of plastic material. The object side surface 211 is convex near the optical axis 290, the image side surface 212 is convex near the optical axis 290, and the object side surface 211 and the image side The surfaces 212 are all aspherical.

The second lens 220 has a negative refractive power and is made of plastic. The object-side surface 221 is concave near the optical axis 290, the image-side surface 222 is convex near the optical axis 290, and the object-side surface 221 and the image side The surfaces 222 are all aspherical.

The third lens 230 has positive refractive power and is made of plastic material. The object side surface 231 is concave near the optical axis 290, the image side surface 232 is convex near the optical axis 290, and the object side surface 231 and the image side The surfaces 232 are all aspherical.

The fourth lens 240 has a negative refractive power and is made of plastic. The object-side surface 241 is convex near the optical axis 290, the image-side surface 242 is concave near the optical axis 290, and the object-side surface 241 and the image side The surfaces 242 are all aspherical, and the object-side surface 241 and the image-side surface 242 have at least one inflection point away from the optical axis 290.

The infrared filter element 270 is made of glass, which is disposed between the fourth lens 240 and the imaging surface 280 and does not affect the focal length of the four-piece dual-band imaging lens group.

Refer to Table 3 and Table 4 below.

In the second embodiment, the curve equation of the aspherical surface is expressed as in the first embodiment. In addition, the definitions of the parameters in the following table are the same as those in the first embodiment, and will not be repeated here.

Together with Table 3 and Table 4, the following data can be derived:

<Third Embodiment>

Please refer to FIGS. 3A and 3B, wherein FIG. 3A shows a schematic diagram of a four-piece dual-band imaging lens set according to a third embodiment of the present invention, and FIG. 3B is a four-piece dual lens of the third embodiment in order from left to right. Curved and distorted aberration curves of the imaging band of the band imaging lens group. As can be seen from FIG. 3A, the four-piece dual-band imaging lens group includes an aperture 300 and an optical group, which includes a first lens 310, a second lens 320, and a third lens 330 in order from the object side to the image side. The fourth lens 340, the infrared filter element 370, and the imaging surface 380, wherein the four-piece dual-band imaging lens group has four refractive lenses. The aperture 300 is disposed before the first lens 310.

The first lens 310 has a positive refractive power and is made of plastic. The object-side surface 311 is convex near the optical axis 390, the image-side surface 312 is convex near the optical axis 390, and the object-side surface 311 and the image side The surfaces 312 are all aspherical.

The second lens 320 has negative refractive power and is made of plastic material. The object-side surface 321 is concave near the optical axis 390, the image-side surface 322 is convex near the optical axis 390, and the object-side surface 321 and the image side The surfaces 322 are all aspherical.

The third lens 330 has a positive refractive power and is made of plastic material. The object-side surface 331 is concave near the optical axis 390, the image-side surface 332 is convex near the optical axis 390, and the object-side surface 331 and the image side The surfaces 332 are all aspherical.

The fourth lens 340 has a negative refractive power and is made of plastic. The object-side surface 341 is convex near the optical axis 390, the image-side surface 342 is concave near the optical axis 390, and the object-side surface 341 and the image side The surfaces 342 are all aspherical, and the object-side surface 341 and the image-side surface 342 have at least one inflection point at a position away from the optical axis 390.

The infrared filter element 370 is made of glass, which is disposed between the fourth lens 340 and the imaging surface 380 and does not affect the focal length of the four-piece dual-band imaging lens group.

Refer to Table 5 and Table 6 below.

In the third embodiment, the curve equation of the aspherical surface is expressed as in the first embodiment. In addition, the definitions of the parameters in the following table are the same as those in the first embodiment, and will not be repeated here.

Together with Tables 5 and 6, the following data can be derived:

<Fourth embodiment>

Please refer to FIGS. 4A and 4B, in which FIG. 4A shows a schematic diagram of a four-piece dual-band imaging lens set according to a fourth embodiment of the present invention, and FIG. 4B is a four-piece dual-type dual lens of the fourth embodiment in order from left to right. Curved and distorted aberration curves of the imaging band of the band imaging lens group. As can be seen from FIG. 4A, the four-piece dual-band imaging lens group includes an aperture 400 and an optical group, which sequentially includes a first lens 410, a second lens 420, and a third lens 430 from the object side to the image side. A fourth lens 440, an infrared filter element 470, and an imaging surface 480, wherein the four-piece dual-band imaging lens group has four refractive lenses. The aperture 400 is disposed before the first lens 410.

The first lens 410 has a positive refractive power and is made of plastic. The object side surface 411 is convex near the optical axis 490, the image side surface 412 is convex near the optical axis 490, and the object side surface 411 and the image side The surfaces 412 are all aspherical.

The second lens 420 has a negative refractive power and is made of plastic. The object-side surface 421 is concave near the optical axis 490, the image-side surface 422 is convex near the optical axis 490, and the object-side surface 421 and the image side The surfaces 422 are all aspherical.

The third lens 430 has a positive refractive power and is made of plastic. The object-side surface 431 is concave near the optical axis 490, the image-side surface 432 is convex near the optical axis 490, and the object-side surface 431 and the image side The surfaces 432 are all aspherical.

The fourth lens 440 has a negative refractive power and is made of plastic material. The object-side surface 441 is convex near the optical axis 490, the image-side surface 442 is concave near the optical axis 490, and the object-side surface 441 and the image side The surfaces 442 are all aspherical, and the object-side surface 441 and the image-side surface 442 have at least one inflexion point away from the optical axis 490.

The infrared filtering element 470 is made of glass, which is disposed between the fourth lens 440 and the imaging surface 480 and does not affect the focal length of the four-piece dual-band imaging lens group.

Refer to Table 7 and Table 8 below.

In the fourth embodiment, the curve equation of the aspherical surface is expressed as in the first embodiment. In addition, the definitions of the parameters in the following table are the same as those in the first embodiment, and will not be repeated here.

Together with Table 7 and Table 8, the following data can be calculated:

<Fifth Embodiment>

Please refer to FIG. 5A and FIG. 5B, wherein FIG. 5A shows a schematic diagram of a four-piece dual-band imaging lens set according to a fifth embodiment of the present invention, and FIG. Curved and distorted aberration curves of the imaging band of the band imaging lens group. As can be seen from FIG. 5A, the four-piece dual-band imaging lens group includes an aperture 500 and an optical group. The optical group includes a first lens 510, a second lens 520, and a third lens 530 in order from the object side to the image side. A fourth lens 540, an infrared filter element 570, and an imaging surface 580, wherein the four-piece dual-band imaging lens group has four refractive lenses. The aperture 500 is disposed before the first lens 510.

The first lens 510 has a positive refractive power and is made of plastic. The object-side surface 511 is convex near the optical axis 590, the image-side surface 512 is convex near the optical axis 590, and the object-side surface 511 and the image side The surfaces 512 are all aspherical.

The second lens 520 has a negative refractive power and is made of plastic material. The object-side surface 521 is concave near the optical axis 590, the image-side surface 522 is convex near the optical axis 590, and the object-side surface 521 and the image side The surfaces 522 are all aspherical.

The third lens 530 has a positive refractive power and is made of plastic material. The object-side surface 531 is concave near the optical axis 590, the image-side surface 532 is convex near the optical axis 590, and the object-side surface 531 and the image side The surfaces 532 are all aspherical.

The fourth lens 540 has a negative refractive power and is made of plastic. The object side surface 541 is convex near the optical axis 590, the image side surface 542 is concave near the optical axis 590, and the object side surface 541 and the image side The surfaces 542 are all aspherical, and the object-side surface 541 and the image-side surface 542 have at least one inflection point away from the optical axis 590.

The infrared filter element 570 is made of glass, which is disposed between the fourth lens 540 and the imaging surface 580 and does not affect the focal length of the four-piece dual-band imaging lens group.

Refer to Table 9 and Table 10 below.

In the fifth embodiment, the curve equation of the aspherical surface is expressed as in the first embodiment. In addition, the definitions of the parameters in the following table are the same as those in the first embodiment, and will not be repeated here.

Together with Tables 9 and 10, the following data can be calculated:

<Sixth Embodiment>

Please refer to FIG. 6A and FIG. 6B, wherein FIG. 6A shows a schematic diagram of a four-piece dual-band imaging lens set according to a sixth embodiment of the present invention, and FIG. 6B is a four-piece dual-type dual lens of the sixth embodiment from left to right. Curved and distorted aberration curves of the imaging band of the band imaging lens group. As can be seen from FIG. 6A, the four-piece dual-band imaging lens group includes an aperture 600 and an optical group. The optical group includes a first lens 610, a second lens 620, and a third lens 630 in order from the object side to the image side. The fourth lens 640, the infrared filter element 670, and the imaging surface 680, wherein the four-piece dual-band imaging lens group has four lenses with refractive power. The aperture 600 is disposed before the first lens 610.

The first lens 610 has a positive refractive power and is made of plastic material. The object-side surface 611 is convex near the optical axis 690, the image-side surface 612 is convex near the optical axis 690, and the object-side surface 611 and the image side The surfaces 612 are all aspherical.

The second lens 620 has a negative refractive power and is made of plastic. The object-side surface 621 is concave near the optical axis 690, the image-side surface 622 is convex near the optical axis 690, and the object-side surface 621 and the image side The surfaces 622 are all aspherical.

The third lens 630 has a positive refractive power and is made of plastic. The object-side surface 631 is concave near the optical axis 690, the image-side surface 632 is convex near the optical axis 690, and the object-side surface 631 and the image side The surfaces 632 are all aspherical.

The fourth lens 640 has a negative refractive power and is made of plastic material. The object-side surface 641 is convex near the optical axis 690, the image-side surface 642 is concave near the optical axis 690, and the object-side surface 641 and the image side The surfaces 642 are all aspherical, and the object-side surface 641 and the image-side surface 642 have at least one inflexion point away from the optical axis 690.

The infrared filtering element 670 is made of glass, which is disposed between the fourth lens 640 and the imaging surface 680 and does not affect the focal length of the four-piece dual-band imaging lens group.

Refer to Table 11 and Table 12 below.

In the sixth embodiment, the curve equation of the aspherical surface is expressed as in the first embodiment. In addition, the definitions of the parameters in the following table are the same as those in the first embodiment, and will not be repeated here.

Together with Table 11 and Table 12, the following data can be calculated:

<Seventh Embodiment>

Please refer to FIG. 7A and FIG. 7B, wherein FIG. 7A shows a schematic diagram of a four-piece dual-band imaging lens set according to a seventh embodiment of the present invention, and FIG. Curved and distorted aberration curves of the imaging band of the band imaging lens group. As can be seen from FIG. 7A, the four-piece dual-band imaging lens group includes an aperture 700 and an optical group, which includes a first lens 710, a second lens 720, and a third lens 730 in order from the object side to the image side. The fourth lens 740, the infrared filter element 770, and the imaging surface 780, wherein the four-piece dual-band imaging lens group has four refractive lenses. The aperture 700 is disposed before the first lens 710.

The first lens 710 has a positive refractive power and is made of plastic. The object-side surface 711 is convex near the optical axis 790, the image-side surface 712 is convex near the optical axis 790, and the object-side surface 711 and the image side The surfaces 712 are all aspherical.

The second lens 720 has a negative refractive power and is made of plastic material. The object-side surface 721 is concave near the optical axis 790, the image-side surface 722 is convex near the optical axis 790, and the object-side surface 721 and the image side The surfaces 722 are all aspherical.

The third lens 730 has a positive refractive power and is made of plastic. The object-side surface 731 is concave near the optical axis 790, the image-side surface 732 is convex near the optical axis 790, and the object-side surface 731 and the image side The surfaces 732 are all aspherical.

The fourth lens 740 has a negative refractive power and is made of plastic. The object-side surface 741 is convex near the optical axis 790, the image-side surface 742 is concave near the optical axis 790, and the object-side surface 741 and the image side The surfaces 742 are all aspherical, and the object-side surface 741 and the image-side surface 742 have at least one inflection point away from the optical axis 790.

The infrared filtering element 770 is made of glass, which is disposed between the fourth lens 740 and the imaging surface 780 and does not affect the focal length of the four-piece dual-band imaging lens group.

Refer to Table 13 and Table 14 below.

In the seventh embodiment, the curve equation of the aspherical surface is expressed as in the first embodiment. In addition, the definitions of the parameters in the following table are the same as those in the first embodiment, and will not be repeated here.

Together with Tables 13 and 14, the following data can be derived:

In the four-piece dual-band imaging lens set provided by the present invention, the lens material can be plastic or glass. When the lens material is plastic, the production cost can be effectively reduced, and when the lens material is glass, the four-piece dual-band imaging lens can be added. The degree of freedom of the configuration of the refractive power of the imaging lens group. In addition, the object-side surface and the image-side surface of the lens in the four-piece dual-band imaging lens group can be aspherical, and the aspherical surface can be easily made into a shape other than a spherical surface, and more control variables are obtained to reduce aberrations, and By reducing the number of lenses used, the total length of the four-piece dual-band imaging lens group of the present invention can be effectively reduced.

In the four-piece dual-band imaging lens group provided by the present invention, as for the lens with refractive power, if the lens surface is convex and the position of the convex surface is not defined, it means that the lens surface is convex at the near optical axis ; If the lens surface is concave and the position of the concave surface is not defined, it means that the lens surface is concave at the near optical axis.

The four-piece dual-band imaging lens set provided by the present invention is more applicable to the mobile focusing optical system according to the visual demand, and has the characteristics of excellent aberration correction and good imaging quality, and can be applied to 3D (three-dimensional) image acquisition in various aspects , Digital cameras, mobile devices, digital tablets or car photography and other electronic imaging systems.

100, 200, 300, 400, 500, 600, 700: aperture

110, 210, 310, 410, 510, 610, 710: the first lens

111, 211, 311, 411, 511, 611, 711: object-side surface

112, 212, 312, 412, 512, 612, 712: image side surface

120, 220, 320, 420, 520, 620, 720: second lens

121, 221, 321, 421, 521, 621, 721: object-side surface

122, 222, 322, 422, 522, 622, 722: image side surface

130, 230, 330, 430, 530, 630, 730: third lens

131, 231, 331, 431, 531, 631, 731: object-side surface

132, 232, 332, 432, 532, 632, 732: image side surface

140, 240, 340, 440, 540, 640, 740: fourth lens

141, 241, 341, 441, 541, 641, 741: object-side surface

142, 242, 342, 442, 542, 642, 742: image side surface

160, 260, 360, 470, 570, 670, 770: infrared filter element

180, 280, 380, 480, 580, 680, 780: imaging plane

190, 290, 390, 490, 590, 690, 790: optical axis

f: Focal length of four-piece dual-band imaging lens group

Fno: Aperture value of four-piece dual-band imaging lens group

FOV: Maximum field angle in the four-piece dual-band imaging lens group

f1: focal length of the first lens

f2: focal length of the second lens

f3: focal length of the third lens

f4: focal length of the fourth lens

f12: The combined focal length of the first lens and the second lens

f23: The combined focal length of the second lens and the third lens

f34: The combined focal length of the third lens and the fourth lens

R1: radius of curvature of the object-side surface of the first lens

R2: radius of curvature of the image side surface of the first lens

R5: radius of curvature of the object-side surface of the third lens

R6: radius of curvature of the image side surface of the third lens

R7: radius of curvature of the object-side surface of the fourth lens

R8: radius of curvature of the image-side surface of the fourth lens

CT1: Thickness of the first lens on the optical axis

CT2: thickness of the second lens on the optical axis

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

FIG. 1A is a schematic diagram of a four-piece dual-band imaging lens group according to the first embodiment of the present invention. FIG. 1B is a graph of the curvature of curvature and distortion of the image plane of the four-piece dual-band imaging lens group of the first embodiment in order from left to right. 2A is a schematic diagram of a four-piece dual-band imaging lens set according to a second embodiment of the present invention. FIG. 2B is a graph of the curvature of curvature and distortion of the image plane of the four-piece dual-band imaging lens group of the second embodiment in order from left to right. 3A is a schematic diagram of a four-piece dual-band imaging lens set according to a third embodiment of the present invention. FIG. 3B is a graph of the curvature of curvature and distortion of the image plane of the four-piece dual-band imaging lens group of the third embodiment in order from left to right. 4A is a schematic diagram of a four-piece dual-band imaging lens group according to a fourth embodiment of the present invention. FIG. 4B is a graph of the curvature of curvature and distortion of the image plane of the four-piece dual-band imaging lens group of the fourth embodiment in order from left to right. 5A is a schematic diagram of a four-piece dual-band imaging lens group according to a fifth embodiment of the present invention. FIG. 5B is a graph of the curvature of curvature and distortion of the image plane of the four-piece dual-band imaging lens group of the fifth embodiment from left to right. 6A is a schematic diagram of a four-piece dual-band imaging lens set according to a sixth embodiment of the present invention. FIG. 6B is a graph of the curvature of curvature and distortion of the image plane of the four-piece dual-band imaging lens group of the sixth embodiment from left to right. 7A is a schematic diagram of a four-piece dual-band imaging lens set according to a seventh embodiment of the present invention. 7B is a graph of the curvature of curvature and distortion of the image plane of the four-piece dual-band imaging lens group of the seventh embodiment from left to right.

100: aperture

110: the first lens

111: Object side surface

112: like side surface

120: second lens

121: Object-side surface

122: like side surface

130: third lens

131: Object side surface

132: Image side surface

140: fourth lens

141: Object side surface

142: like side surface

170: Infrared filter element

180: imaging surface

190: Optical axis

Claims (13)

A four-piece dual-band imaging lens group, including an aperture and an optical group composed of four lenses, from the object side to the image side in order: the aperture; a first lens with a positive refractive power, the first The object-side surface of a lens is convex near the optical axis, the image-side surface of the first lens is convex near the optical axis, and at least one of the object-side surface and the image-side surface of the first lens is aspheric; a second The lens has a negative refractive power, the object-side surface of the second lens is concave near the optical axis, the image-side surface of the second lens is convex near the optical axis, and the object-side surface and the image-side surface of the second lens are at least A surface is aspheric; a third lens has positive refractive power, the object-side surface of the third lens is concave near the optical axis, the image-side surface of the third lens is convex near the optical axis, and the second lens At least one of the object-side surface and the image-side surface is aspheric; and a fourth lens with negative refractive power, the object-side surface of the fourth lens is convex near the optical axis, and the image-side surface of the fourth lens is near The optical axis is concave, at least one of the object-side surface and the image-side surface of the fourth lens is aspherical; wherein the radius of curvature of the object-side surface of the third lens is R5, and the radius of curvature of the image-side surface of the third lens is R6, and meet the following conditions: 4<R5/R6<14. The four-piece dual-band imaging lens group according to claim 1, wherein the focal length of the first lens is f1 and the focal length of the second lens is f2, and the following conditions are satisfied: -0.8<f1/f2<-0.4. The four-piece dual-band imaging lens group according to claim 1, wherein the focal length of the second lens is f2 and the focal length of the third lens is f3, and the following conditions are satisfied: -1.6<f2/f3<-0.9. The four-piece dual-band imaging lens group according to claim 1, wherein the focal length of the third lens is f3 and the focal length of the fourth lens is f4, and the following conditions are satisfied: -0.8<f3/f4<-0.3. The four-piece dual-band imaging lens group according to claim 1, wherein the focal length of the first lens is f1 and the focal length of the third lens is f3, and the following conditions are satisfied: 0.6<f1/f3<1.0. The four-piece dual-band imaging lens group according to claim 1, wherein the focal length of the second lens is f2 and the focal length of the fourth lens is f4, and the following conditions are satisfied: 0.3<f2/f4<1.2. The four-piece dual-band imaging lens group according to claim 1, wherein the focal length of the first lens is f1, the combined focal length of the second lens and the third lens is f23, and the following conditions are satisfied: 0.1<f1/f23 <0.7. The four-piece dual-band imaging lens group according to claim 1, wherein the combined focal length of the second lens and the third lens is f23, and the focal length of the fourth lens is f4, and the following conditions are satisfied: -1.6<f23/ f4<-0.9. The four-piece dual-band imaging lens group according to claim 1, wherein the combined focal length of the first lens and the second lens is f12, and the combined focal length of the third lens and the fourth lens is f34, and the following conditions are satisfied: 0.7<f12/f34<1.5. The four-piece dual-band imaging lens group according to claim 1, wherein the overall focal length of the four-piece dual-band imaging lens group is f, and the distance from the object-side surface of the first lens to the imaging surface on the optical axis is TL, and meet the following conditions: 0.5<f/TL<0.8. The four-piece dual-band imaging lens group according to claim 1, wherein the radius of curvature of the object-side surface of the first lens is R1, and the radius of curvature of the image-side surface of the first lens is R2, and the following conditions are satisfied: -2.1 <R1/R2<-0.4. The four-piece dual-band imaging lens group according to claim 1, wherein the radius of curvature of the object-side surface of the fourth lens is R7, and the radius of curvature of the image-side surface of the fourth lens is R8, and the following conditions are satisfied: 1.3< R7/R8<2.1. The four-piece dual-band imaging lens group according to claim 1, wherein the thickness of the second lens on the optical axis is CT2, and the thickness of the first lens on the optical axis is CT1, and the following conditions are satisfied: 0.3< CT2/CT1<0.7.

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