CN201054035Y - Three-lens type optical image capturing lens - Google Patents

Abstract

The utility model relates to a three lens formula optics are got for instance camera lens contains according to the preface by the thing side: the first lens piece with positive diopter is a crescent aspheric lens; the second lens piece with negative diopter is a crescent aspheric lens; a third lens element with negative diopter, which is an M-shaped aspheric lens, and the object side surface and the image side surface of the third lens element are both M-shaped, and the central surface of the third lens element on the optical axis can be a convex surface or a concave surface; an infrared filter; and an image sensor. And the following conditions are satisfied: d is more than or equal to 0.4f and less than 0.9f, R1/R2 is more than or equal to 0.3 f and less than 0.6, Fno is more than or equal to 2.8 and less than 3.6, br/f is more than 0.2 and less than 0.4, f1/f is more than 0.5 and less than 1.1, and f3/f is more than-4.0 and less than-1.1, wherein f and Fno are the effective focal length and the focal number of the system, d is the distance from the object side surface of the first lens element to the image side surface of the third lens element, R1 is the curvature radius of the object side surface of the first lens element, R2 is the curvature radius of the image side surface of the first lens element, Fno is the focal number of the imaging lens system, br is the back focal length of the imaging lens system, and f1 and f3 are the effective focal lengths of the first and the third lens elements, thereby achieving the purpose of effectively improving.

Description

Three-element optical imaging lens

technical field

The utility model relates to a three-mirror optical imaging lens (optical imaging lens), which is mainly aimed at mobile phone lenses or lenses using image sensors such as CCD (charge coupled device) or CMOS (complementary metal oxide semiconductor), Provided is an optical imaging lens consisting of three lens elements.

Background technique

With the advancement of technology, electronic products are constantly developing towards the direction of thin, light, small and multi-functional, and electronic products such as: digital camera (Digital Still Camera), computer camera (PC camera), network camera (Network camera), mobile phone, etc. In addition to already having an imaging device (lens), even personal digital assistants (PDAs) and other devices also have the need to add an imaging device (lens); and in order to be portable and meet the needs of humanization, the imaging device not only needs to have Good imaging quality also requires smaller volume and lower cost, so that the applicability of the imaging device can be effectively improved, especially for mobile phones, the above requirements or conditions are even more important.

Since the traditional spherical ground glass lens has more material options and is more beneficial for correcting chromatic aberration, it has been widely used in the industry. However, the spherical ground glass lens is used when the focal number (F number) is small and the field of view ( field angle) is relatively large, it is still difficult to correct aberrations such as spherical aberration and astigmatism; and in order to overcome the above-mentioned shortcomings of the traditional spherical ground glass lens, the current imaging device has used an aspheric plastic lens or used Aspherical molded glass lens to obtain better imaging quality, such as US invention patents: US6,795,253, US6,961,191, US6,441,971, Pub.No.US2004/0061953A1, Pub.No.US2004/0190158A1, Pub.No .US2004/0190162A1, Pub.No.US2004/023 1823A1, Pub.No.US2005/0231822A1, or Japanese invention patents: Patent No. 3567327, Patent No. 3717488, Patent No. 3768509, Patent No. 3816095, Patent Publication Patent Publication No. 2005-084404, Patent Publication No. 2006-047858, Patent Publication No. 2005-309210, Patent Publication No. 2005-227755, Patent Publication No. 2005-345919, Patent Publication No. 2005-292235, Patent Publication No. 2004-004566, Patent Publication No. 2005 - No. 338234 and many other optical imaging lens structure designs including three lens components (lens components)/three lenses (lens elements) from the object side): the first, second, third and third lens groups (lens components)/lens elements (lens elements), as for the differences or technical features of the above-mentioned multiple invention patents, it is determined by the following factors Changes or combinations only: The shapes of the three lens groups/lenses described in each patent are designed differently. For example, the first, second, and third lens groups/lenses are all meniscus shape lenses. Or the first and second lens groups/lenses are crescent-shaped and the third lens group/lenses are plano-concave shape or plano-convex shape; and/or described in each patent The corresponding convex/concave directions of the three lens groups/lenses are different. For example, the convex/concave surfaces of the first/second/third third lens groups/lenses can be arranged on the object side/image side and other variable combinations; and/ Or the positive/negative refractive powers of the three lens groups/lenses described in each patent are different, for example, the diopters of the first, second, third and third lens groups/lenses are positive, negative, and positive in sequence Or different combinations of positive, positive, negative, etc.; and/or related optical data between the three lens groups/lenses described in each patent, such as f (effective focal length of the imaging lens system), d (first lens The distance from the side of the object to the image side of the third lens), R1 (the radius of curvature of the object side of the first lens), R2 (the radius of curvature of the image side of the first lens), Fno (the focal number of the imaging lens system), br (the back focal length of the imaging lens system), f1 (the effective focal length of the first lens element), f3 (the effective focal length of the third lens element), etc., respectively satisfy different conditions, such as 0.8<f1/f<2.0, 0.5 <(|R2|-R1)/(R1+|R2|), and 1.5<f3/f<3.0 refer to Japanese Patent No. 3717488; it can be seen from the above that the design of an optical imaging lens with three lens groups/lenses In other words, its design technology is not particularly difficult in the field of optical imaging lens technology, and can even be regarded as prior art. As long as different changes or combinations can be studied in the above-mentioned various factors, it can be regarded as novel. Novelty or innovative step can be applied for and authorized as a patent. However, the overall length of the above-mentioned optical imaging lens is still too large, so that the imaging lens cannot have a smaller volume or lower cost, and the correction and elimination of aberrations or the reduction of the chief ray angle are not ideal, and it is difficult to meet the needs of electronic products. Striving for light, thin and high-performance requirements also limits the applicability of imaging lenses, especially in mobile phones.

Contents of the invention

The utility model discloses a three-mirror optical imaging lens (imaging lens), which sequentially includes from the object side: a first lens element of positive refractive power (a first lens element of positive refractive power), which is a crescent-shaped an aspheric lens with its convex surface on the object side; a negative refractive power second lens element which is a crescent-shaped aspheric lens with its convex surface on the image side; a negative refractive power third lens element , is an M-shaped aspheric lens, and its object side and image side are both M-shaped, and its central surface on the optical axis can be convex or concave; an infrared filter; and an image sensor; and The same optical axis arrangement; and, the imaging lens satisfies the following conditions: 0.4f≤d<0.9f, 0.3<|R1/R2|<0.6, 2.8≤Fno<3.6, 0.2<br/f<0.4, 0.5<f1/f<1, and -4.0<f3/f<-1.1, where f is the effective focal length of the imaging lens system, d is the distance from the object side of the first lens element to the image side of the third lens, R1 is the radius of curvature of the object side of the first lens element, R2 is the radius of curvature of the image side of the first lens element, Fno is the focal number of the imaging lens system, br is the back focal length of the imaging lens system, and f1 is the first lens The effective focal length of the element, f3 is the effective focal length of the third lens element; to effectively eliminate the aberration and reduce the chief ray angle, so that the imaging lens has high resolution and can effectively reduce the length of the lens, so that the imaging lens has a relatively high Small size and low cost improve the applicability of the imaging lens.

As an improvement of the present utility model, one side of the convex surface and the concave surface of the first lens part of the three-element optical imaging lens can be aspherical, and of course both sides can be aspherical; the second One side of the convex surface and the concave surface of the lens piece can be an aspheric surface, and of course both sides can be aspheric surfaces; The surfaces are all aspherical.

As another improvement of the present utility model, wherein said imaging lens is provided with a pre-diaphragm, and its aperture stop (aperture stop) is arranged on the object side convex surface (convex object-side surface) of the first lens element , to form a three-lens optical imaging lens with high resolution and capable of effectively reducing the overall length of the lens. It can effectively improve the applicability of the imaging lens.

Description of drawings

Fig. 1 is a schematic diagram of the optical structure of the first embodiment of the utility model;

Fig. 2 is a schematic diagram of the optical path of the first embodiment of the utility model;

Fig. 3 is the transverse light fan (transverse ray fan plot) diagram of five different fields of view (actual image heights 0, 0.575, 1.15, 1.725, 2.3mm) of the first embodiment of the present utility model;

Fig. 4 is the field curvature (field curvature) diagram of the imaging of the utility model first embodiment;

Fig. 5 is the distortion (distortion) figure of the imaging of the first embodiment of the present utility model;

Fig. 6 is the modulation transfer function ( modulation transfer function) diagram;

Fig. 7 is the relative illumination (relative illumination) diagram that the full field of view of the first embodiment of the present invention corresponds to the zero field of view;

Fig. 8 is a schematic diagram of the optical structure of the second embodiment of the utility model;

Fig. 9 is a schematic diagram of the optical path of the second embodiment of the utility model;

Fig. 10 is the transverse ray fan plot (transverse ray fan plot) of five different fields of view (actual image heights 0, 0.675, 1.35, 2.025, 2.7mm) of the second embodiment of the present invention;

Fig. 11 is the field curvature (field curvature) diagram of the imaging of the second embodiment of the present invention;

Fig. 12 is a distortion (distortion) diagram of the imaging of the second embodiment of the present invention;

Fig. 13 is the modulation transfer function ( modulation transfer function) diagram;

Fig. 14 is a relative illumination (relative illumination) diagram generated by the full field of view corresponding to the zero field of view of the second embodiment of the present invention;

Fig. 15 is a schematic diagram of the optical structure of the third embodiment of the present invention;

Fig. 16 is a schematic diagram of the optical path of the third embodiment of the utility model;

Fig. 17 is a transverse ray fan plot (transverse ray fan plot) of five different fields of view (actual image heights 0, 0.575, 1.15, 1.725, 2.3 mm) of the third embodiment of the present invention;

Fig. 18 is the field curvature (field curvature) diagram of the imaging of the third embodiment of the present invention;

Fig. 19 is a distortion diagram of the imaging of the third embodiment of the present invention;

Fig. 20 is the modulation transfer function ( modulation transfer function) diagram;

Fig. 21 is a relative illumination (relative illumination) diagram generated by the full field of view corresponding to the zero field of view of the third embodiment of the present invention;

Fig. 22 is a schematic diagram of the optical structure of the fourth embodiment of the utility model;

Fig. 23 is a schematic diagram of the optical path of the fourth embodiment of the utility model;

Fig. 24 is the transverse ray fan plot (transverse ray fan plot) of five different fields of view (actual image heights 0, 0.575, 1.15, 1.725, 2.3 mm) of the fourth embodiment of the present invention;

Fig. 25 is a field curvature diagram of the imaging of the fourth embodiment of the present invention;

Fig. 26 is a distortion diagram of the imaging of the fourth embodiment of the present invention;

Fig. 27 is the modulation transfer function ( modulation transfer function) diagram;

Fig. 28 is a diagram of relative illumination generated by the full field of view corresponding to the zero field of view in the fourth embodiment of the present invention.

Explanation of reference numerals: L1-first lens part; 11-object side (convex); 12-image side (concave); 13-aperture stop; L2-second lens part; 21-image side (convex); 22 - object side (concave surface); L3 - third lens element; 4 - infrared filter; 5 - image sensor; 51 - sensing surface.

Detailed ways

Below in conjunction with accompanying drawing, the utility model is further described:

Referring to Figs. 1 and 2, which are respectively a schematic structural view and a schematic view of the optical path of the first embodiment of the present invention, the three-mirror optical imaging lens (optical imaging lens) of the present invention, in order from the object side (in order from the object side) includes: a positive diopter first lens element (a first lens element of positiverefractive power) L1 is located on the object side (on the object side), which is a crescent-shaped aspheric lens, and its convex surface 11 is on the Object side, and its concave surface 12 is on the image side (on the image side), and its convex surface 11 and concave surface 12 have at least one aspheric surface; a second lens element of negative diopter (a second lens element of negativerefractive power) L2 Located between the first lens element L1 and the third lens element L3, it is a crescent-shaped aspheric lens, and its convex surface 21 is on the image side, and at least one side of its convex surface 21 and concave surface 22 is an aspherical surface; a negative The third lens element of diopter (a third lens element of negative refractive power) is an M-shaped aspheric lens, and its object side and image side are both M-shaped, and its central surface on the optical axis can be a convex surface or a concave surface; an infrared filter (IR cut-off filter) 4; and an image sensor (image sensing chip) 5; and are arranged sequentially on the same optical axis (optical axis) X as shown in Figure 1; At this time, the light first passes through the first lens element L1, the second lens element L2 and the third lens element L3, and then passes through the infrared filter 4 to be imaged on the sensing surface 51 of the image sensor (image sensing chip) 5 as shown in FIG. Figure 2 shows. The utility model image pickup lens is provided with a front aperture, and its aperture stop (aperture stop) 13 is located on the object side convex surface (convex object-side surface) 11 of the first lens element L1 as shown in Figures 1 and 2.

And the utility model three-lens type optical imaging lens satisfies the following conditions (the following conditions are satisfied):

0.4f≤d＜0.9f;

0.3<|R1/R2|<0.6;

2.8≤Fno<3.6;

0.2<br/f<0.4;

0.5<f1/f<1; and

-4.0<f3/f<-1.1;

Wherein, f is the effective focal length of the imaging lens (system), d is the distance from the object side of the first lens element to the image side of the third lens, R1 is the radius of curvature of the object side of the first lens element, and R2 is the first lens element The radius of curvature of the side of the image, Fno is the focal number of the imaging lens (system), br is the back focal length of the imaging lens (system), f1 is the effective focal length of the first lens element, and f3 is the effective focal length of the third lens element Focal length: By virtue of the above structure, the aberration can be effectively corrected and the chief ray angle can be reduced, so that the imaging lens of the utility model has high resolution and can effectively reduce the length of the lens, so that the imaging lens has a smaller volume and lower cost, And improve the applicability of the imaging lens.

Now enumerate several preferred embodiments, and explain as follows respectively:

<First embodiment>

Please refer to Fig. 1 to Fig. 7, which are respectively the schematic structural diagram of the first embodiment, the schematic diagram of the optical path, and the lateral light fan diagrams ( Transverseray fan plot), imaging field curvature diagram, imaging distortion diagram, five fields of view (actual image height 0, 0.575, 1.15, 1.725, 2.3mm) corresponding to 0 to 160LP/mm spatial frequency (spatial frequency) generated modulation transfer function (modulation transfer function) diagram, and the relative illumination (relative illumination) diagram generated by the zero field of view corresponding to the full field of view.

The following table (1) respectively lists the optical surface number # (surface number) in order from the objectside of the first embodiment, each optical surface type (Type), each on the optical axis The radius of curvature R (unit: mm) (the radius of curvature R) of the optical surface, the distance D (unit: mm) (the on-axis surface spacing) between the surfaces on the optical axis, and the lens material.

Table I)

Surf# optical surface number type type R radius of curvature D spacing Lens material Object (OBJ) STANDARD ∞ ∞ 1 (STO) aperture stop (convex 11 of L1) EVENA SPH aspherical surface 1.045866 0.6254172 APL5014DP 2 (Concave 12 of L1) EVENA SPH aspherical surface 2.856472 0.333 3 (Concave 22 of L2) EVENA SPH aspherical surface -1.211588 0.3 PC-AD5503 4 (convex 21 of L2) EVENAS PH aspherical surface -1.567001 0.71 5 (object side of L3) EVENASPH aspherical surface 7.428193 0.635 APL5014DP 6 (image side of L3) EVENASPH aspherical surface 3.652651 0.3 7 The object side of the infrared filter STANDARD ∞ 0.3 BK7 8 The image side of the infrared filter STANDARD ∞ 0.6895 Sensing surface of the image sensor (IMG) STANDARD ∞

The following table (2) lists the coefficients (Coeff) of each optical surface:

Table II)

ConicK CoeffonA Coeffon B CoeffonC CoeffonD CoeffonE CoeffonF 0.2920592 0.087064049 -0.53200801 -2.0272798 3.1146592 -0.20910606 -2.7558402 -10.3516 -0.16571862 0.74653154 -5.7031601 13.152124 -3.1970224 -37.065607 0 -0.19424105 2.4541884 -11.689832 31.523331 -37.98107 0 0 0.25064416 0.3038517 -0.51127647 -1.7983047 1.1041925 0 0 -0.1543527 0.072206238 -0.017051835 0.00214664 -5.6296258e-005 0 0 -0.14069475 0.050215116 -0.017573297 0.00333273 -0.00032903218 0

Also, Z=ch2/{1+[1-(1+K)c2h2]1/2}+Ah4+Bh6+Ch8+Dh10+EH12+Fh14 is its aspherical surface formula (A spherical Surface Formula), wherein, c is the curvature, h is the height of the lens, K is the cone coefficient (Conic Constant), A is the fourth-order aspheric coefficient (4 ^th Order A spherical Coefficient), B is the sixth-order aspherical coefficient (6 ^th Order A spherical Coefficient), C is the ^8th Order A spherical Coefficient, ^D is the 10th Order A spherical Coefficient, E is the ^12th Order A spherical Coefficient, F is the 14th Order A spherical coefficient (14 ^th Order A spherical Coefficient).

The materials of the first, second and third lens parts L1, L2 and L3 of the first embodiment are all plastic materials, such as using the plastic materials of models APL5014DP, PC-AD5503 and APL5014DP respectively, and the material of the infrared filter 4 is The glass material is such as model BK7 glass material, and its thickness is 0.3mm.

In addition, the effective focal length f of the lens system is 3.568mm, and the distance d between the object-side convex surface 11 of the first lens element L1 and the image side of the third lens element L3 is 2.603mm, which can satisfy the condition: 0.4f≤d<0.9f; According to table (1), it can be known that |R1/R2| is 0.366, which can satisfy the condition: 0.3<|R1/R2|<0.6; and Fno is 2.88, which can satisfy the condition: 2.8≤Fno<3.6; and br/f is 0.36 , can satisfy the condition: 0.2<br/f<0.4; and f1/f is 0.756, can satisfy the condition: 0.5<f1/f<1; and f3/f is -3.929, can satisfy the condition: -4.0<f3/f <-1.1.

And by above-mentioned table (one), table (two) and shown in Fig. 1 to Fig. 7, it can be seen that the total length of the lens (totallength) of the first embodiment imaging lens is 3.89292mm, thus can prove the imaging of the present utility model The lens can effectively correct aberrations and reduce the angle of the chief ray, so that the imaging lens has high resolution and can effectively reduce the length of the lens, so that the utility model has a smaller volume and lower cost, thereby improving the applicability of the utility model .

<Second Embodiment>

Please refer to Fig. 8 to Fig. 14, which are respectively the schematic structural diagram of the second embodiment, the schematic diagram of the optical path, and the lateral light fan diagrams ( Transverseray fan plot), imaging field curvature diagram, imaging distortion diagram, five fields of view (actual image height 0, 0.675, 1.35, 2.025, 2.7mm) corresponding to 0 to 160LP/mm spatial frequency (spatial frequency) generated modulation transfer function (modulation transfer function) diagram, and the relative illumination (relative illumination) diagram generated by the zero field of view corresponding to the full field of view.

The following table (1) respectively lists the optical surface number # (surface number) in order from the object side of the second embodiment, each optical surface type (Type), and each on the optical axis The radius of curvature R (unit: mm) (the radius of curvature R) of the optical surface, the distance D (unit: mm) (the on-axis surface spacing) between the surfaces on the optical axis, and the lens material.

Table I)

Surf# optical surface number type type R radius of curvature D spacing Lens material Object (OBJ) STANDARD ∞ ∞ 1 (STO) aperture stop (convex 11 of L1) EVENASPH aspherical surface 0.9521654 0.7 APL5014DP 2 (Concave 12 of L1) EVENASPH aspherical surface 1.868359 0.46 3 (Concave 22 of L2) EVENASPH aspherical surface -0.8740775 0.33 OKP4 4 (convex 21 of L2) EVENASPH aspherical surface -1.178223 0.48 5 (object side of L3) EVENASPH aspherical surface -11.23862 0.96 APL5014DP 6 (image side of L3) EVENASPH aspherical surface 18.92478 0.47 7 The object side of the infrared filter S TANDARD ∞ 0.145 BK7 8 The image side of the infrared filter STANDARD ∞ 0.6852577 Sensing surface of the image sensor (IMG) STANDARD ∞

The following table (2) lists the coefficients (Coeff) of each aspheric surface:

Table II)

ConicK CoeffonA Coeffon B CoeffonC CoeffonD CoeffonE 1.2388473 0.10756979 -0.25703696 2.5485253 -2.9346596 2.7326332 8.764503 0.068892289 0.96971112 -6.1227955 17.56916 -20.81957 -0.3800384 0.17443527 1.1430828 -1.3541767 4.1598877 -12.997629 -0.512312 0.2573969 0.40575552 -0.65066411 0.21857035 0.044341757 0 -0.047939702 -0.011027204 0.001404473 -9.55247e-005 0 -8.75739e+016 -0.035433299 0.0042659581 0.00037998373 -0.000121579 0

Also, Z=ch2/{1+[1-(1+K)c2h2]1/2}+Ah4+Bh6+Ch8+Dh10+Eh12 is its aspherical surface formula (A spherical Surface Formula), where c is the curvature , h is the lens height, K is the cone coefficient (Conic Constant), A is the fourth order aspheric coefficient (4 ^th Order A spherical Coefficient), B is the sixth order aspherical coefficient (6 ^th Order A spherical Coefficient), C is The eighth-order aspherical coefficient (8 ^th Order A spherical Coefficient), D is the tenth-order aspheric coefficient (10 ^th Order A spherical Coefficient), and E is the twelfth-order aspherical coefficient (12 ^th Order A spherical Coefficient).

The materials of the first, second, and third lens elements L1, L2, and L3 of the second embodiment can respectively use the plastic materials of models APL5014DP, OKP4, and APL5014DP, and the material of the infrared filter 4 can use the glass material of model BK7. Its thickness is 0.145mm.

In addition, the effective focal length f of the lens system is 4.45408mm, and the distance d between the object-side convex surface 11 of the first lens element L1 and the image side of the third lens element L3 is 2.93mm, which can satisfy the condition: 0.4f≤d<0.9f; According to table (1), it can be seen that: |R1/R2| is 0.51, which can satisfy the condition: 0.3<|R1/R2|<0.6; and Fno is 3.5, which can satisfy the condition: 2.8≤Fno<3.6; and br/f is 0.295 , can satisfy the condition: 0.2<br/f<0.4; while f1/f is 0.634, can satisfy the condition: 0.5<f1/f<1; and f3/f is -2.888, can satisfy the condition: -4.0<f3/f <-1.1.

And shown in above-mentioned table (1), table (2) and Fig. 8 to Fig. 14, it can be seen that the total length of the lens (total length) of the imaging lens of the second embodiment is 4.23026 mm, so it can be proved that the imaging lens of the present utility model The aberration can be effectively corrected and the angle of the chief ray can be reduced, so that the imaging lens has high resolution and can effectively reduce the length of the lens, so that the utility model has a smaller volume and lower cost, thereby improving the applicability of the utility model.

<Third embodiment>

Please refer to FIG. 15 to FIG. 21, which are respectively the structural schematic diagram, the optical path schematic diagram, and the lateral light fan diagrams of five different fields of view (actual image heights of 0, 0.575, 1.15, 1.725, and 2.3 mm) of the third embodiment ( Transverseray fan plot), imaging field curvature diagram, imaging distortion diagram, five fields of view (actual image height 0, 0.575, 1.15, 1.725, 2.3mm) corresponding to 0 to 200LP/mm spatial frequency (spatial frequency) generated modulation transfer function (modulation transfer function) diagram, and the relative illumination (relative illumination) diagram generated by the zero field of view corresponding to the full field of view.

The following table (1) respectively lists the optical surface number # (surface number) in order from the object side of the third embodiment, each optical surface type (Type), each on the optical axis The radius of curvature R (unit: mm) (the radius of curvature R) of the optical surface, the distance D (unit: mm) (the on-axis surface spacing) between the surfaces on the optical axis, and the lens material.

Table I)

Surf# optical surface number type type R radius of curvature D spacing Lens material Object (OBJ) STANDARD ∞ ∞ 1 (STO) aperture stop (convex 11 of L1) EVENASPH aspherical surface 1.114541 0.66 L-BAL42 (concave surface 12 of L1) EVENASPH aspherical surface 2.935603 0.333 (concave surface 22 of L2) EVENASPH aspherical surface -1.211588 0.3 PC-AD5503 4 (convex 21 of L2) EVENAS PH aspherical surface -1.567001 0.71 5 (object side of L3) EVENAS PH aspherical surface 7.428193 0.635 APL5014DP 6 (image side of L3) EVENAS PH aspherical surface 3.652651 0.3 7 The object side of the infrared filter STANDARD ∞ 0.3 BK7 8 The image side of the infrared filter STANDARD ∞ 0.663 Sensing surface of the image sensor (IMG) STANDARD ∞

The following table (2) lists the coefficients (Coeff) of each aspheric surface:

Table II)

Also, Z=ch2/{1+[1-(1+K)c2h2]1/2}+Ah4+Bh6+Ch8+Dh10+Eh12 is its aspherical surface formula (A spherical Surface Formula), where c is the curvature , h is the lens height, K is the cone coefficient (Conic Constant), A is the fourth order aspheric coefficient (4 ^th Order A spherical Coefficient), B is the sixth order aspherical coefficient (6 ^th Order A spherical Coefficient), C is The eighth-order aspherical coefficient (8 ^th Order A spherical Coefficient), D is the tenth-order aspheric coefficient (10 ^th Order A spherical Coefficient), and E is the twelfth-order aspherical coefficient (12 ^th Order A spherical Coefficient).

The material of the first lens element L1 of the third embodiment can use the molded glass material of the model L-BAL42, and the materials of the second and third lens elements L2 and L3 can respectively use the plastic material of the model PC-AD5503 and APL5014DP, and The material of the infrared filter 4 is glass material of model BK7, and its thickness is 0.3 mm.

Conick CoeffonA Coeffon B CoeffonC CoeffonD CoeffonE 0 -1.02671936 -0.068884 0.24955338 -0.23824146 0.011541093 0 0.039706576 1.62437299 2.8582053 -5.1534801 0 0 -0.19424105 2.4541884 11.689832 31.523331 -37.98107 0 0.12064416 0.3038517 0.91127647 -1.7983047 1.1041925 0 0.4543327 0.072206238 -0.017051835 0.00214664 -5.6296258e-005 0 -0.14069475 0.150215116 -0.017573297 0.00333273 -0.00032903218

In addition, the effective focal length f of the lens system is 3.60562mm, and the distance d between the object-side convex surface 11 of the first lens element L1 and the image side of the third lens element L3 is 2.638mm, which can satisfy the condition: 0.4f≤d<0.9f; According to table (1), it can be known that |R1/R2| is 0.38, which can satisfy the condition: 0.3<|R1/R2|<0.6; and Fno is 2.88, which can satisfy the condition: 2.8≤Fno<3.6; and br/f is 0.349 , can satisfy the condition: 0.2<br/f<0.4; and f1/f is 0.755, can satisfy the condition: 0.5<f1/f<1, and f3/f is -3.872, can satisfy the condition: -4.0<f3/f <-1.1.

And shown in above-mentioned table (1), table (2) and Fig. 15 to Fig. 21, can know that the total length of lens (totallength) of the imaging lens of the present utility model is 3.901mm, and so can prove the imaging lens of the present utility model The aberration can be effectively corrected and the angle of the chief ray can be reduced, so that the imaging lens has high resolution and can effectively reduce the length of the lens, so that the utility model has a smaller volume and lower cost, thereby improving the applicability of the utility model.

<Fourth Embodiment>

Please refer to FIG. 22 to FIG. 28, which are respectively the structural schematic diagram of the fourth embodiment, the optical path schematic diagram, and the lateral light fan diagrams ( Transverseray fan plot), imaging field curvature diagram, imaging distortion diagram, five fields of view (actual image height 0, 0.575, 1.15, 1.725, 2.3mm) corresponding to 0 to 200LP/mm spatial frequency (spatial frequency) generated modulation transfer function (modulation transfer function) diagram, and the relative illumination (relative illumination) diagram generated by the zero field of view corresponding to the full field of view.

The following table (1) respectively lists the optical surface number # (surface number) in order from the objectside of the fourth embodiment, each optical surface type (Type), each on the optical axis The radius of curvature R (unit: mm) (the radius of curvature R) of the optical surface, the distance D (unit: mm) (the on-axis surface spacing) between the surfaces on the optical axis, and the lens material.

Table I)

Surf# optical surface number type type R radius of curvature D spacing Lens material Object (OBJ) STANDARD ∞ ∞ 1 (STO) aperture stop (convex 11 of L1) EVENASPH aspherical surface 1.131739 0.659822 L-BAL42 (concave surface 12 of L1) EVENASPH aspherical surface 2.980781 0.362801 3 (Concave 22 of L2) EVENASPH aspherical surface -1.147414 0.312704 PC-AD5503 4 (convex 21 of L2) EVENASPH aspherical surface -1.402019 0.780297 5 (object side of L3) EVENASPH aspherical surface 9.344721 0.670206 E48R 6 (image side of L3) EVENASPH aspherical surface 3.242521 0.295425 7 The object side of the infrared filter STANDARD ∞ 0.3 BK7 8 The image side of the infrared filter STANDARD ∞ 0.492000 Sensing surface of the image sensor (IMG) STANDARD ∞

The following table (2) lists the coefficients (Coeff) of each aspheric surface:

Table II)

ConicK CoeffonA Coeffon B Coeffon CoeffonD Coeffon CoeffonF Coeff on GF 0 0014349 0.072306 1.604128 2.150179 -3165406 1.326687 0 0 0025049 -0.177248 0.659086 -1.470068 -2261540 -0.430519 0 0 -0.325856 3141126 -17244902 56935162 101.980482 81.543450 -46.417413 0 0.067450 -0.270228 0.874534 1.292196 0.995264 -0.873310 0.557583 -1088.132364 -0.155882 0088906 -0029565 0001290 0.001439 0.000733 -0000313 -20.667084 -0.116499 0.043999 -0.016342 0002851 -0000250 -0.000051 0.000014

Again, Z=ch2/{1+[1-(1+K)c2h2]1/2}+Ah4+Bh6+Ch8+Dh10+Eh12+Fh14+Gh16 is its aspheric equation

(A spherical Surface Formula), where, c is the curvature, h is the lens height, K is the cone coefficient (Conic Constant), A is the fourth-order aspheric coefficient (4 ^th Order A spherical Coefficient), B is the sixth-order aspherical coefficient Spherical Coefficient (6 ^th Order A spherical Coefficient), C is the ^8th Order A spherical Coefficient ^, D is the 10th Order A spherical Coefficient, E is the 12th Order A spherical Coefficient Spherical Coefficient (12 ^th Order A spherical Coefficient), F is the 14th Order Aspherical Coefficient (14 ^th Order Aspherical Coefficient), G is the 16th Order A spherical Coefficient (14 ^th Order A spherical Coefficient).

The material of the first lens element L1 of the fourth embodiment can use the molded glass material of the model L-BAL42, and the materials of the second and third lens elements L2 and L3 can respectively use the plastic material of the model PC-AD5503 and E48R, and The material of the infrared filter 4 can utilize the glass material of model BK7, and its thickness is 0.3mm.

In addition, the effective focal length f of the lens system is 3.56392mm, and the distance d between the object-side convex surface 11 of the first lens element L1 and the image side of the third lens element L3 is 2.78583mm, which can satisfy the condition: 0.4f≤d<0.9f; According to table (1), it can be known that |R1/R2| is 0.379679, which can satisfy the condition: 0.3<|R1/R2|<0.6; and Fno is 2.8, which can satisfy the condition: 2.8≤Fno<3.6; and br is 1.087425mm, br/f is 0.305120, which can satisfy the condition: 0.2<br/f<0.4; while f1 is 2.745667mm, f1/f is 0.770405, and can satisfy the condition: 0.5<f1/f<1, while f3 is -9.739370mm, f3 /f is -2.732769, which can satisfy the condition: -4.0<f3/f<-1.1.

From the above table (1), table (2) and shown in Figure 22 to Figure 28, it can be seen that the total length of the imaging lens of the present utility model is 3.873mm, and this can prove that the imaging lens of the present utility model The aberration can be effectively corrected and the angle of the chief ray can be reduced, so that the imaging lens has high resolution and can effectively reduce the length of the lens, so that the utility model has a smaller volume and lower cost, thereby improving the applicability of the utility model.

What is shown above is only a preferred embodiment of the present invention, and is only illustrative, not restrictive, of the present invention. Those skilled in the art understand that many changes, modifications, and even equivalent changes can be made within the spirit and scope defined by the claims of the present invention, but all will fall within the protection scope of the present invention.

Claims (11)

1. A three-mirror optical imaging lens, characterized in that: it includes along the same optical axis and from the object side in sequence: A first positive diopter lens element, which is a crescent-type aspheric lens, and its convex surface is on the object side; a negative diopter second lens element, which is a crescent-type aspheric lens, and its convex surface is on the image side; A third lens element with a negative diopter is an M-shaped aspheric lens, and its object side and image side are both M-shaped, and its central surface on the optical axis can be convex or concave; an infrared filter; and an image sensor; Among them, the following conditions are met: 0.4f≤d＜0.9f; 0.3<|R1/R2|<0.6; 2.8≤Fno<3.6; 0.2<br/f<0.4; 0.5<f1/f<1; -4.0<f3/f<-1.1; Wherein, f is the effective focal length of the imaging lens system, d is the distance from the object side of the first lens element to the image side of the third lens element, R1 is the radius of curvature of the object side of the first lens element, and R2 is the image of the first lens element The radius of curvature of the side surface, Fno is the focal number of the imaging lens system, br is the back focal length of the imaging lens system, f1 is the effective focal length of the first lens element, and f3 is the effective focal length of the third lens element. 2 . The three-element optical imaging lens according to claim 1 , wherein at least one of the convex and concave surfaces of the crescent-shaped first lens element is aspherical. 3 . 3 . The three-element optical imaging lens according to claim 1 , wherein at least one of the convex and concave surfaces of the crescent-shaped second lens element is aspherical. 4 . 4. The three-element optical imaging lens according to claim 1, wherein at least one of the object side and the image side of the M-shaped third lens element is an aspheric surface. 5. The three-element optical imaging lens according to claim 1, characterized in that: said imaging lens is provided with a front aperture. 6. The three-lens optical imaging lens according to claim 5, wherein the aperture stop of the optical imaging lens is located on the object-side convex surface of the first lens element. 7. The three-mirror optical imaging lens according to claim 1, characterized in that: the first, second and third lens parts are made of plastic material respectively, and the infrared filter is made of glass material and its thickness is 0.3mm. 8. According to claim 7, the three-mirror optical imaging lens is characterized in that: the first, second and third lens parts are respectively made of plastic materials of models APL5014DP, PC-AD5503 and APL5014DP, and the infrared rays The filter is made of glass material of model BK7. 9. The three-mirror optical imaging lens according to claim 1, characterized in that: the first, second and third lens parts are made of plastic material respectively, and the infrared filter is made of glass material And its thickness is 0.145mm. 10. The three-mirror optical imaging lens according to claim 9, characterized in that: the first, second and third lens parts are made of plastic materials of models APL5014DP, OKP4 and APL5014DP respectively, and the infrared filter The sheet is made of glass material of type BK7. 11. The three-element optical imaging lens according to claim 1, wherein the first lens element is made of molded glass material, and the second and third lens elements are respectively made of plastic material, The infrared filter is made of glass material and its thickness is 0.3mm.

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