CN106054358A

CN106054358A - Optical imaging lens

Info

Publication number: CN106054358A
Application number: CN201510470408.XA
Authority: CN
Inventors: 唐子健; 王佩琪
Original assignee: Genius Electronic Optical Xiamen Co Ltd
Current assignee: Genius Electronic Optical Xiamen Co Ltd
Priority date: 2015-08-04
Filing date: 2015-08-04
Publication date: 2016-10-26
Anticipated expiration: 2035-08-04
Also published as: CN106054358B

Abstract

The invention discloses an optical imaging lens, which comprises a first lens, an aperture, a second lens, a third lens and a fourth lens in sequence from the object side to the image side along an optical axis, and is characterized in that each lens is provided with an object side face and an image side face; the first lens has positive refractive index; the second lens has refractive index, and the image side face of the second lens is provided with a convex surface portion located at an area nearby the circumference; the third lens has positive refractive index, and an object side face of the third lens is provided with a concave surface portion located at an area nearby the optical axis; and the fourth lens has refractive index, and the image side face of the fourth lens is provided with a concave surface portion located at an area nearby the optical axis and a convex surface portion located at an area nearby the circumference. The optical imaging lens further satisfies the following conditional expressions: abs(upsilon1-upsilon2)>=25, (G12+T3)/(T1+G23)>=2.25, ALT/Gaa>=2.45. According to the optical imaging lens, the length of the lens can be shortened under the condition of maintaining excellent imaging quality.

Description

Optical imaging lens

Technical Field

The present invention relates to an optical lens, and more particularly, to an optical imaging lens.

Background

The specifications of portable electronic products are changing day by day, key components of the camera lens are developing more diversified, the application is not only limited to shooting images and recording videos, but also environment monitoring, driving record shooting and the like are added, and along with the progress of image sensing technology, the requirements of consumers on imaging quality and the like are improved. Therefore, the design of the camera lens not only requires good imaging quality and smaller lens space, but also needs to consider the improvement of the field angle and the aperture size in response to the dynamic and light-deficient environment.

The design of the camera lens is not only to reduce the lens with good imaging quality in equal proportion to manufacture the camera lens with both imaging quality and miniaturization, and the design process involves material characteristics and also needs to consider practical problems of production aspects such as manufacturing and assembly yield.

Therefore, the technical difficulty of the miniaturized lens is obviously higher than that of the traditional lens, so that how to manufacture the camera lens which accords with the dynamic and insufficient light environment, continuously improve the imaging quality of the camera lens and shorten the length of the camera lens is a continuously advanced target in the industry.

Disclosure of Invention

Therefore, an object of the present invention is to provide an optical imaging lens capable of maintaining good optical performance even when the length of the lens system is shortened.

The optical imaging lens of the present invention sequentially includes, along an optical axis from an object side to an image side, a first lens element, an aperture stop, a second lens element, a third lens element, and a fourth lens element, where the first lens element to the fourth lens element respectively include an object side surface facing the object side and allowing the imaging light to pass therethrough and an image side surface facing the image side and allowing the imaging light to pass therethrough.

The first lens element has positive refractive index; the second lens element with refractive index has a convex surface at the periphery thereof; the third lens element with positive refractive index has a concave surface portion located in a region near an optical axis; the fourth lens element has a refractive index, and the image-side surface of the fourth lens element has a concave portion located in a region near the optical axis and a convex portion located in a region near the circumference.

The optical imaging lens has only four lenses with refractive indexes, the first lens has an abbe number of 1, the second lens has an abbe number of 2, the first lens has a thickness of T1 on an optical axis, the third lens has a thickness of T3 on the optical axis, an air gap between the first lens and the second lens on the optical axis is G12, an air gap between the second lens and the third lens on the optical axis is G23, the sum of the thicknesses of the first lens, the second lens, the third lens and the fourth lens on the optical axis is ALT, the sum of the three air gaps between the first lens and the fourth lens on the optical axis is Gaa, and the following conditions are satisfied: and | upsilon 1-upsilon 2| is not less than 25, (G12+ T3)/(T1+ G23) | 2.25, and ALT/Gaa is not less than 2.45.

The optical imaging lens has the beneficial effects that: by the concave-convex shape design and arrangement of the object side surface or the image side surface of the lens, the optical imaging lens still has the optical performance of effectively overcoming the aberration under the condition of shortening the system length, and provides better imaging quality.

Drawings

Other features and advantages of the present invention will become apparent from the following detailed description of embodiments thereof, with reference to the accompanying drawings, in which:

FIG. 1 is a schematic diagram illustrating a face structure of a lens;

FIG. 2 is a schematic view illustrating a surface type concave-convex structure of a lens and a light focus;

FIG. 3 is a schematic view illustrating a face structure of a lens according to an example I;

FIG. 4 is a schematic diagram illustrating a second exemplary lens configuration;

FIG. 5 is a schematic view illustrating a surface structure of a lens according to a third exemplary embodiment;

FIG. 6 is a schematic configuration diagram illustrating a first embodiment of an optical imaging lens according to the present invention;

FIG. 7 is a diagram of longitudinal spherical aberration and various aberrations of the first embodiment;

FIG. 8 is a table diagram illustrating optical data for each lens of the first embodiment;

FIG. 9 is a table diagram illustrating aspherical coefficients of the lenses of the first embodiment;

FIG. 10 is a schematic configuration diagram illustrating a second embodiment of an optical imaging lens according to the present invention;

FIG. 11 is a diagram of longitudinal spherical aberration and various aberrations of the second embodiment;

FIG. 12 is a table diagram illustrating optical data for each lens of the second embodiment;

FIG. 13 is a table diagram illustrating aspherical coefficients of the lenses of the second embodiment;

FIG. 14 is a schematic configuration diagram illustrating a third embodiment of an optical imaging lens according to the invention;

FIG. 15 is a longitudinal spherical aberration and various aberrations diagram of the third embodiment;

FIG. 16 is a table diagram illustrating optical data for each lens of the third embodiment;

FIG. 17 is a table diagram illustrating aspherical coefficients of the lenses of the third embodiment;

FIG. 18 is a schematic configuration diagram illustrating a fourth embodiment of an optical imaging lens according to the invention;

FIG. 19 is a longitudinal spherical aberration and various aberrations diagram of the fourth embodiment;

FIG. 20 is a table diagram illustrating optical data for each lens of the fourth embodiment;

FIG. 21 is a table diagram illustrating aspherical coefficients of the lenses of the fourth embodiment;

FIG. 22 is a schematic configuration diagram illustrating a fifth embodiment of an optical imaging lens according to the invention;

FIG. 23 is a longitudinal spherical aberration and various aberrations diagram of the fifth embodiment;

FIG. 24 is a table diagram illustrating optical data for each lens of the fifth embodiment;

fig. 25 is a table diagram illustrating aspherical coefficients of the lenses of the fifth embodiment;

FIG. 26 is a schematic configuration diagram illustrating a sixth embodiment of an optical imaging lens according to the invention;

FIG. 27 is a longitudinal spherical aberration and various aberrations diagram of the sixth embodiment;

FIG. 28 is a table diagram illustrating optical data for each lens of the sixth embodiment;

fig. 29 is a table diagram illustrating aspherical coefficients of the lenses of the sixth embodiment;

FIG. 30 is a schematic configuration diagram illustrating a seventh embodiment of an optical imaging lens according to the invention;

FIG. 31 is a longitudinal spherical aberration and various aberrations diagram of the seventh embodiment;

FIG. 32 is a table diagram illustrating optical data for each lens of the seventh embodiment;

fig. 33 is a table diagram illustrating aspherical coefficients of the lenses of the seventh embodiment;

FIG. 34 is a schematic configuration diagram illustrating an eighth embodiment of an optical imaging lens according to the invention;

FIG. 35 is a longitudinal spherical aberration and aberration diagrams of the eighth embodiment;

fig. 36 is a table diagram illustrating optical data of each lens of the eighth embodiment;

fig. 37 is a table diagram illustrating aspherical coefficients of the lenses of the eighth embodiment;

FIG. 38 is a table diagram illustrating optical parameters of the first to eighth embodiments of the optical imaging lens; and

fig. 39 is a table diagram illustrating optical parameters of the first to eighth embodiments of the optical imaging lens.

Detailed Description

Before the present invention is described in detail, it should be noted that in the following description, like elements are represented by like reference numerals.

In the present specification, the term "a lens element having a positive refractive index (or a negative refractive index)" means that the refractive index of the lens element on the optical axis calculated by the gaussian optical theory is positive (or negative). The image side surface and the object side surface are defined as a range through which imaging light passes, wherein the imaging light includes a chief ray (chief ray) Lc and a marginal ray (marginal ray) Lm, as shown in fig. 1, I is an optical axis, and the lens is radially symmetrical with the optical axis I as a symmetry axis, a region on the optical axis through which light passes is an area a near the optical axis, and a region through which marginal light passes is an area C near the circumference. More specifically, the following methods are used to determine the surface shape, the area near the optical axis, the area near the circumference, or the ranges of a plurality of areas:

1. fig. 1 is a cross-sectional view of a lens in the radial direction. When the area is judged, a central point is defined as an intersection point of the lens surface and the optical axis I, and a conversion point is a point on the lens surface and a tangent line passing through the point is vertical to the optical axis. If there are plural conversion points outward in the radial direction, the first conversion point and the second conversion point are in sequence, and the conversion point farthest from the optical axis in the radial direction on the effective radius is the Nth conversion point. The range between the central point and the first conversion point is an area near the optical axis, the area radially outward of the Nth conversion point is an area near the circumference, and different areas can be distinguished according to the conversion points in the middle. Further, the effective radius is the perpendicular distance from the intersection of the marginal ray Lm with the lens surface to the optical axis I.

2. As shown in fig. 2, the shape irregularity of the region is determined on the image side or the object side at the intersection point of the light beam (or the light beam extension line) passing through the region in parallel with the optical axis I (light beam focus determination method). For example, when the light passes through the region, the light is focused toward the image side, and the focal point of the optical axis is located at the image side, such as the R point in fig. 2, the region is a convex surface. On the contrary, if the light passes through the certain region, the light diverges, and the extension line and the focal point of the optical axis are on the object side, for example, at point M in fig. 2, the region is a concave surface portion, so that a convex surface portion is formed between the central point and the first transition point, and the region radially outward of the first transition point is a concave surface portion; as can be seen from fig. 2, the transition point is a boundary point between the convex surface portion and the concave surface portion, so that the region and the region adjacent to the region in the radial direction can be defined to have different surface shapes with the transition point as a boundary. In addition, the determination of the surface shape in the region near the optical axis I can be determined by a method of determination by a person of ordinary skill in the art, in which the R value (which refers to the radius of curvature of the paraxial region, and generally refers to the R value in a lens database (lens data) in optical software) is positive or negative. When the R value is positive, the object side is judged to be a convex surface part, and when the R value is negative, the object side is judged to be a concave surface part; in the case of the image side surface, when the R value is positive, it is determined as a concave surface portion, and when the R value is negative, it is determined as a convex surface portion, and the unevenness determined by this method is determined in the same manner as the light focus determination.

3. If there is no transition point on the lens surface, the area near the optical axis I is defined as 0-50% of the effective radius, and the area near the circumference is defined as 50-100% of the effective radius.

Referring to fig. 3, the image-side surface of the lens of example one has only the first transition point on the effective radius, and the first zone is the area around the optical axis I and the second zone is the area around the circumference. The R value of the image side surface of the lens is positive, so that the area near the optical axis I is judged to have a concave surface part; the surface shape of the circumferential vicinity is different from the inner side area immediately radially adjacent to the circumferential vicinity. That is, the surface shapes of the area near the circumference and the area near the optical axis I are different; the circumferential vicinity has a convex portion.

Referring to fig. 4, the object-side surface of the lens of example two has a first and a second transition point on the effective radius, and the first zone is the region near the optical axis I and the third zone is the region near the circumference. The R value of the object side surface of the lens is positive, so that the area near the optical axis is judged to be a convex surface part; the region (second region) between the first transition point and the second transition point has a concave surface portion, and the region (third region) near the circumference has a convex surface portion.

Referring to fig. 5, the object-side surface of the lens of example three has no transition point on the effective radius, and the effective radius is 0% to 50% of the area around the optical axis I and 50% to 100% of the area around the circumference. The R value of the area near the optical axis I is positive, so that the object side surface is provided with a convex surface part in the area near the optical axis I; there is no transition point between the area near the circumference and the area near the optical axis I, so the area near the circumference has a convex surface portion.

Referring to fig. 6 and 8, the optical imaging lens 10 according to the first embodiment of the present invention includes, in order from an object side to an image side along an optical axis I, a first lens element 3, an aperture stop 2, a second lens element 4, a third lens element 5, a fourth lens element 6, and a filter 9. When light emitted from an object enters the optical imaging lens 10, and passes through the first lens 3, the stop 2, the second lens 4, the third lens 5, the fourth lens 6, and the filter 9, an Image is formed on an Image Plane 100(Image Plane). The Filter 9 is an infrared Filter (IR Cut Filter) for preventing infrared rays in the light from transmitting to the image plane 100 to affect the image quality. It should be noted that the object side is toward the object to be photographed, and the image side is toward the imaging plane 100.

The first lens element 3, the second lens element 4, the third lens element 5, the fourth lens element 6, and the filter 9 each have an object-side surface 31, 41, 51, 61, 91 facing the object side and allowing the imaging light to pass therethrough, and an image-side surface 32, 42, 52, 62, 92 facing the image side and allowing the imaging light to pass therethrough. The object-side surfaces 31, 41, 51, 61 and the image-side surfaces 32, 42, 52, 62 are aspheric.

In addition, in order to satisfy the requirement of light weight of the product, the first lens element 3 to the fourth lens element 6 are all made of plastic material with refractive index, but the material of the first lens element 3 to the fourth lens element 6 is not limited thereto.

The first lens element 3 has a positive refractive index. The object-side surface 31 of the first lens element 3 is a convex surface, and has a convex portion 311 located in the vicinity of the optical axis I and a convex portion 312 located in the vicinity of the circumference, and the image-side surface 32 of the first lens element 3 has a concave portion 321 located in the vicinity of the optical axis I and a convex portion 322 located in the vicinity of the circumference.

The second lens element 4 has a negative refractive index. The object-side surface 41 of the second lens element 4 is a concave surface and has a concave portion 411 located in the vicinity of the optical axis I and a concave portion 412 located in the vicinity of the circumference, and the image-side surface 42 of the second lens element 4 has a concave portion 421 located in the vicinity of the optical axis I and a convex portion 422 located in the vicinity of the circumference.

The third lens element 5 has a positive refractive index. The object-side surface 51 of the third lens element 5 has a concave portion 511 located in the vicinity of the optical axis I and a convex portion 512 located in the vicinity of the circumference, and the image-side surface 52 of the third lens element 5 is a convex surface and has a convex portion 521 located in the vicinity of the optical axis I and a convex portion 522 located in the vicinity of the circumference.

The fourth lens element 6 has a negative refractive index. The object-side surface 61 of the fourth lens element 6 has a convex surface 611 located in the vicinity of the optical axis I and a concave surface 612 located in the vicinity of the circumference, and the image-side surface 62 of the fourth lens element 6 has a concave surface 621 located in the vicinity of the optical axis I and a convex surface 622 located in the vicinity of the circumference.

In the first embodiment, only the lens elements have refractive indexes.

Other detailed optical data of the first embodiment is shown in fig. 8, and the overall system focal length (EFL) of the first embodiment is 2.295mm, half field of view (HFOV) is 37.999 °, aperture value (Fno) is 2.391, and the system length is 3.352 mm. The system length is a distance from the object side surface 31 of the first lens element 3 to the image plane 100 on the optical axis I.

In addition, the object-side surfaces 31, 41, 51, 61 and the image-side surfaces 32, 42, 52, 62 of the first lens element 3, the second lens element 4, the third lens element 5, and the fourth lens element 6 are aspheric surfaces, and the aspheric surfaces are defined by the following formula:

Z (Y) = \frac{Y^{2}}{R} / (1 + \sqrt{1 - (1 + K) \frac{Y^{2}}{R^{2}}}) + Σ_{i = 1}^{n} a_{2 i} \times Y^{2 i} - - - (1)

wherein:

y: the distance between a point on the aspheric curve and the optical axis I;

z: the depth of the aspheric surface (the vertical distance between a point on the aspheric surface which is Y away from the optical axis I and a tangent plane tangent to the vertex on the optical axis I of the aspheric surface);

r: the radius of curvature of the lens surface;

k: cone constant (conc constant);

a_2i: aspheric coefficients of order 2 i.

The aspheric coefficients of the object side surface 31 of the first lens 3 to the image side surface 62 of the fourth lens 6 in formula (1) are shown in fig. 9. In fig. 9, the column number 31 indicates the aspheric coefficient of the object-side surface 31 of the first lens element 3, and so on.

Fig. 38 and 39 show relationships between important parameters in the optical imaging lens 10 according to the first embodiment.

Wherein,

t1 is the thickness of the first lens 3 on the optical axis I;

t2 is the thickness of the second lens 4 on the optical axis I;

t3 is the thickness of the third lens 5 on the optical axis I;

t4 is the thickness of the fourth lens 6 on the optical axis I;

g12 is an air gap on the optical axis I between the first lens 3 and the second lens 4;

g23 is an air gap on the optical axis I between the second lens 4 and the third lens 5;

g34 is an air gap on the optical axis I between the third lens 5 and the fourth lens 6;

gaa is the sum of three air gaps on the optical axis I of the first lens 3 to the fourth lens 6, i.e., the sum of G12, G23 and G34;

ALT is the sum of thicknesses of the first lens 3, the second lens 4, the third lens 5 and the fourth lens 6 on the optical axis I, i.e., the sum of T1, T2, T3 and T4;

TTL is the distance from the object-side surface 31 of the first lens element 3 to the image plane 100 on the optical axis I;

BFL is the distance from the image-side surface 62 of the fourth lens element 6 to the image plane 100 on the optical axis I; and

the EFL is the system focal length of the optical imaging lens 10.

In addition, redefining:

G4F is an air gap on the optical axis I between the fourth lens 6 and the filter 9;

TF is the thickness of the filter 9 on the optical axis I;

GFI is the air gap on the optical axis I between the filter 9 and the image plane 100;

f1 is the focal length of the first lens 3;

f2 is the focal length of the second lens 4;

f3 is the focal length of the third lens 5;

f4 is the focal length of the fourth lens 6;

n1 is the refractive index of the first lens 3;

n2 is the refractive index of the second lens 4;

n3 is the refractive index of the third lens 5;

n4 is the refractive index of the fourth lens 6;

ν 1 is Abbe number (Abbe number) of the first lens 3, which can also be referred to as Abbe number;

ν 2 is an abbe coefficient of the second lens 4;

ν 3 is an abbe coefficient of the third lens 5; and

ν 4 is an abbe coefficient of the fourth lens 6; .

Referring to fig. 7, the drawings of (a) illustrate longitudinal spherical aberration (longitudinal spherical aberration) of the first embodiment, and the drawings of (b) and (c) illustrate astigmatic aberration (astigmatic aberration) of the first embodiment in sagittal direction and meridional direction, respectively, on the image plane 100, and the drawings of (d) illustrate distortion aberration (distortion aberration) of the first embodiment on the image plane 100. In the longitudinal spherical aberration diagram of the first embodiment shown in fig. 7(a), the curves formed by each wavelength are very close and close to the middle, which means that the off-axis light beams with different heights of each wavelength are all concentrated near the imaging point, and the deviation of the off-axis light beams with different heights is controlled within the range of ± 0.02mm as can be seen from the deviation of the curve of each wavelength, so that the present embodiment indeed improves the spherical aberration with the same wavelength, and in addition, the distances between the three representative wavelengths are also very close, which means that the imaging positions of the light beams with different wavelengths are very concentrated, thereby improving the chromatic aberration.

In the two astigmatic aberration diagrams of FIGS. 7(b) and 7(c), the variation of the focal length of the three representative wavelengths over the entire field of view is within + -0.04 mm, which illustrates that the optical system of the first embodiment can effectively eliminate the aberrations. The distortion aberration diagram of fig. 7(d) shows that the distortion aberration of the first embodiment is maintained within a range of ± 2.5%, which indicates that the distortion aberration of the first embodiment meets the imaging quality requirement of the optical system, and thus the first embodiment can provide better imaging quality under the condition that the system length is shortened to about 3.352mm compared with the conventional optical lens, so that the first embodiment can shorten the lens length and enlarge the shooting angle under the condition of maintaining good optical performance, thereby realizing thinner product design.

Referring to fig. 10, a second embodiment of an optical imaging lens system 10 according to the present invention is substantially similar to the first embodiment, and only the optical data, aspheric coefficients and parameters of the lenses 3, 4, 5 and 6 are slightly different. Note here that, in fig. 10, the same reference numerals of the concave surface portion and the convex surface portion as those of the first embodiment are omitted for clarity of illustration.

The detailed optical data is shown in fig. 12, and the overall system focal length of the second embodiment is 2.261mm, the half field angle (HFOV) is 38.229 °, the aperture value (Fno) is 2.356, and the system length is 3.393 mm.

As shown in fig. 13, the aspheric coefficients of the object-side surface 31 of the first lens element 3 to the image-side surface 62 of the fourth lens element 6 in the formula (1) are shown.

In addition, the relationship between the important parameters in the optical imaging lens 10 of the second embodiment is shown in fig. 38 and 39.

Referring to fig. 11, it can be seen from the longitudinal spherical aberration of (a), the astigmatic aberration of (b), and the distortion aberration of (c), and the figure of (d) that the second embodiment can maintain good optical performance.

As can be seen from the above description, the advantages of the second embodiment over the first embodiment are: the half angle of view of the second embodiment is larger than that of the first embodiment, and the aperture value of the second embodiment is smaller than that of the first embodiment.

Referring to fig. 14, a third embodiment of the optical imaging lens system 10 of the present invention is substantially similar to the first embodiment, except that the optical data, aspheric coefficients and parameters of the lenses 3, 4, 5 and 6 are more or less different, and the image-side surface 52 of the third lens element 5 has a convex portion 521 located in the vicinity of the optical axis I and a concave portion 523 located in the vicinity of the circumference. Note here that, in order to clearly show the drawing, reference numerals of the concave surface portion and the convex surface portion which are the same as those of the first embodiment are omitted in fig. 14.

The detailed optical data is shown in fig. 16, and the overall system focal length of the third embodiment is 2.318mm, the half field angle (HFOV) is 38.000 °, the aperture value (Fno) is 2.415, and the system length is 3.372 mm.

As shown in fig. 17, the aspheric coefficients of the object-side surface 31 of the first lens element 3 to the image-side surface 62 of the fourth lens element 6 in the formula (1) are shown.

Fig. 38 and 39 show relationships between important parameters in the optical imaging lens 10 according to the third embodiment.

Referring to fig. 15, it can be seen from the longitudinal spherical aberration of (a), the astigmatic aberration of (b), and the distortion aberration of (c), and the figure of (d) that the third embodiment can maintain good optical performance.

As can be seen from the above description, the third embodiment has the following advantages over the first embodiment: the half-field angle of the third embodiment is larger than that of the first embodiment, and the third embodiment is easier to manufacture than the first embodiment and therefore has a higher yield.

Referring to fig. 18, a fourth embodiment of the optical imaging lens system 10 according to the present invention is substantially similar to the first embodiment, except that the optical data, aspheric coefficients and parameters of the lenses 3, 4, 5 and 6 are more or less different, the object-side surface 41 of the second lens element 4 has a convex portion 413 located in the vicinity of the optical axis I and a concave portion 412 located in the vicinity of the circumference, and the object-side surface 61 of the fourth lens element 6 is a concave surface and has a concave portion 613 located in the vicinity of the optical axis I and a concave portion 612 located in the vicinity of the circumference. Note here that, in order to clearly show the drawing, reference numerals of the concave surface portion and the convex surface portion which are the same as those of the first embodiment are omitted in fig. 18.

The detailed optical data is shown in fig. 20, and the overall system focal length of the fourth embodiment is 2.362mm, the half field angle (HFOV) is 37.992 °, the aperture value (Fno) is 2.461, and the system length is 3.412 mm.

As shown in fig. 21, the aspheric coefficients of the object-side surface 31 of the first lens element 3 to the image-side surface 62 of the fourth lens element 6 in the formula (1) are shown.

Fig. 38 and 39 show relationships between important parameters in the optical imaging lens 10 according to the fourth embodiment.

Referring to fig. 19, it can be seen from the longitudinal spherical aberration of (a), the astigmatic aberrations of (b) and (c), and the distortion aberration of (d) that the fourth embodiment can maintain good optical performance.

As can be seen from the above description, the advantages of the fourth embodiment over the first embodiment are: the fourth embodiment is superior in image quality to the first embodiment, and is easier to manufacture than the first embodiment and thus has a higher yield.

Referring to fig. 22, a fifth embodiment of the optical imaging lens system 10 according to the present invention is substantially similar to the first embodiment, except that the optical data, aspheric coefficients and parameters of the lenses 3, 4, 5 and 6 are more or less different, the image-side surface 32 of the first lens element 3 is a convex surface and has a convex portion 323 located in the vicinity of the optical axis I and a convex portion 322 located in the vicinity of the circumference, the object-side surface 41 of the second lens element 4 has a convex portion 413 located in the vicinity of the optical axis I and a concave portion 412 located in the vicinity of the circumference, and the object-side surface 61 of the fourth lens element 6 is a concave surface and has a concave portion 613 located in the vicinity of the optical axis I and a concave portion 612 located in the vicinity of the circumference. Note here that, in order to clearly show the drawing, reference numerals of the concave surface portion and the convex surface portion which are the same as those of the first embodiment are omitted in fig. 22.

The detailed optical data is shown in fig. 24, and the overall system focal length of the fifth embodiment is 2.360mm, the half field angle (HFOV) is 37.998 °, the aperture value (Fno) is 2.459, and the system length is 3.407 mm.

As shown in fig. 25, the aspheric coefficients of the object-side surface 31 of the first lens element 3 to the image-side surface 62 of the fourth lens element 6 in the formula (1) are shown.

Fig. 38 and 39 show relationships between important parameters in the optical imaging lens 10 according to the fifth embodiment.

Referring to fig. 23, it can be seen from the longitudinal spherical aberration of (a), the astigmatic aberration of (b), and the distortion aberration of (c), and the figure of (d) that the fifth embodiment can maintain good optical performance.

As can be seen from the above description, the advantages of the fifth embodiment over the first embodiment are: the imaging quality of the fifth lens is better than that of the first embodiment, and the fifth embodiment is easier to manufacture than the first embodiment and therefore has a higher yield.

Referring to fig. 26, a sixth embodiment of the optical imaging lens system 10 according to the present invention is substantially similar to the first embodiment, except that the optical data, aspheric coefficients and parameters of the lenses 3, 4, 5 and 6 are more or less different, the object-side surface 41 of the second lens element 4 has a convex portion 413 located in the vicinity of the optical axis I and a concave portion 412 located in the vicinity of the circumference, and the object-side surface 61 of the fourth lens element 6 is a concave surface and has a concave portion 613 located in the vicinity of the optical axis I and a concave portion 612 located in the vicinity of the circumference. Note here that, in order to clearly show the drawing, reference numerals of the concave surface portion and the convex surface portion which are the same as those of the first embodiment are omitted in fig. 26.

The detailed optical data is shown in fig. 28, and the overall system focal length of the sixth embodiment is 2.362mm, the half field angle (HFOV) is 37.997 °, the aperture value (Fno) is 2.461, and the system length is 3.411 mm.

As shown in fig. 29, the aspheric coefficients of the object-side surface 31 of the first lens element 3 to the image-side surface 62 of the fourth lens element 6 in the formula (1) are shown.

Fig. 38 and 39 show relationships between important parameters in the optical imaging lens 10 according to the sixth embodiment.

Referring to fig. 27, it can be seen from the longitudinal spherical aberration of (a), the astigmatic aberrations of (b) and (c), and the distortion aberration of (d) that the sixth embodiment can maintain good optical performance.

As can be seen from the above description, the advantages of the sixth embodiment over the first embodiment are: the sixth embodiment is superior in image quality to the first embodiment, and is easier to manufacture than the first embodiment and thus has a higher yield.

Referring to fig. 30, a seventh embodiment of the optical imaging lens system 10 of the present invention is substantially similar to the first embodiment, and only the optical data, aspheric coefficients and parameters of the lenses 3, 4, 5 and 6 are slightly different. Note here that, in fig. 30, the same reference numerals of the concave surface portion and the convex surface portion as those of the first embodiment are omitted for clarity of illustration.

The detailed optical data is shown in fig. 32, and the overall system focal length of the seventh embodiment is 2.316mm, the half field angle (HFOV) is 38.000 °, the aperture value (Fno) is 2.413, and the system length is 3.396 mm.

As shown in fig. 33, the aspheric coefficients of the object-side surface 31 of the first lens element 3 to the image-side surface 62 of the fourth lens element 6 in formula (1) are shown.

Fig. 38 and 39 show relationships between important parameters in the optical imaging lens 10 according to the seventh embodiment.

Referring to fig. 31, it can be seen from the longitudinal spherical aberration of (a), the astigmatic aberration of (b), and the distortion aberration of (c), that the seventh embodiment can maintain good optical performance.

As can be seen from the above description, the advantages of the seventh embodiment over the first embodiment are: the half angle of view of the seventh embodiment is larger than that of the first embodiment, and the imaging quality of the seventh embodiment is better than that of the first embodiment.

Referring to fig. 34, an eighth embodiment of the optical imaging lens system 10 of the present invention is substantially similar to the first embodiment, except that the optical data, aspheric coefficients and parameters of the lenses 3, 4, 5 and 6 are more or less different, and the image-side surface 32 of the first lens element 3 is a convex surface and has a convex portion 323 in the vicinity of the optical axis I and a convex portion 322 in the vicinity of the circumference. Note here that, in order to clearly show the drawing, reference numerals of concave and convex portions which are the same as those of the first embodiment are omitted in fig. 34.

The detailed optical data is shown in fig. 36, and the overall system focal length of the eighth embodiment is 2.337mm, the half field angle (HFOV) is 37.998 °, the aperture value (Fno) is 2.250, and the system length is 4.112 mm.

As shown in fig. 37, the aspheric coefficients of the object-side surface 31 of the first lens element 3 to the image-side surface 62 of the fourth lens element 6 in the formula (1) are shown.

Fig. 38 and 39 show relationships between important parameters in the optical imaging lens 10 according to the eighth embodiment.

Referring to fig. 35, it can be seen from the longitudinal spherical aberration of (a), the astigmatic aberrations of (b) and (c), and the distortion aberration of (d) that the eighth embodiment can maintain good optical performance.

As can be seen from the above description, the eighth embodiment has the following advantages over the first embodiment: the aperture value of the eighth embodiment is smaller than that of the first embodiment.

Referring to fig. 38 and 39, which are table diagrams of optical parameters of the eight embodiments, when the relationship between the optical parameters in the optical imaging lens 10 of the present invention satisfies the following conditional expressions, the optical performance still has better performance under the condition of shortened system length, so that when the present invention is applied to the related portable electronic device, a thinner product can be manufactured:

first, when | ν 1- ν 2| ≧ 25 is satisfied, it is used to correct chromatic aberration on-axis and chromatic aberration off-axis well while keeping these chromatic aberrations stable. When the difference is lower than the lower limit, the on-axis chromatic aberration becomes an insufficiently corrected state. When the abbe number of the second lens 4 is set to a small value in order to improve such insufficient correction of chromatic aberration, the chromatic aberration on the axis can be corrected well, but conversely, the off-axis chromatic aberration of magnification becomes excessive and worsens.

Secondly, for the conditions of (G12+ T3)/(T1+ G23) ≥ 2.25, ALT/Gaa ≥ 2.45, T3/Gaa ≥ 1.2, (T3+ T4)/G12 ≥ 2.4, ALT/G12 ≥ 3.6, (T3+ T4)/(T1+ T2) ≤ 2.05, ALT/(G23+ G34) ≤ 12.45, T3/(G23+ G34) ≤ 7.4, T4/T2 ≤ 1.35, and υ 1/υ 4 ≤ 1.05, which are preferably limited to the conditions of 2.25 ≤ G2 + T2)/(T2 + G2) + 2 ≤ 6.5, 2.45 ≤ Ga/a ≤ 7, 1.20 ≤ T2/Gaa)/(Gauss 3.5, and T364 ≤ T2 + T2/2, and/2 are not more detrimental to the objective of the overall imaging of the lens 2, and the parameters of the lens can be kept as well as 2, or avoid the problem that the assembly is affected or the difficulty of manufacturing is increased due to the undersize of any parameter.

And thirdly, when EFL/ALT is more than or equal to 1.3, designing the relation between the total thickness ALT of all the lenses and the focal length EFL of the optical imaging lens 10. EFL/ALT is preferably limited to 1.3-1.6, and when the ratio is too large, the optical path length becomes too long, and thinning of the optical imaging lens 10 becomes difficult; when the aforementioned ratio is too small, the optical path length becomes too short, correction of each aberration becomes difficult, and error sensitivity at the time of manufacturing is too strict.

And fourthly, when the condition that upsilon 1/upsilon 4 is more than or equal to 0.95 and less than or equal to 1.05 is met, controlling each aberration to be finely corrected. When the limit is exceeded, each aberration is not easily finely corrected.

However, in view of the unpredictability of the optical system design, the above-listed exemplary defining relationships can be optionally combined in unequal numbers for the embodiments of the present invention, so as to shorten the length, reduce the aperture value, increase the field angle, improve the imaging quality, or improve the assembly yield of the optical imaging lens 10 of the present invention, thereby improving the disadvantages of the prior art. In addition to the above relations, other additional concave-convex curved surface arrangements of a single lens or a plurality of lenses may be designed to enhance the control of the system performance and/or resolution in implementing the present invention, for example, a convex portion 413 located in the vicinity of the optical axis I and a concave portion 412 located in the vicinity of the circumference may be optionally formed on the object-side surface 41 of the second lens 4. It should be noted that these details need not be selectively incorporated into other embodiments of the present invention without conflict.

In summary, the optical imaging lens 10 of the present invention can achieve the following effects and advantages, so as to achieve the objectives of the present invention:

first, the first lens element 3 has a positive refractive index, which is favorable for focusing light, and the aperture stop 2 is disposed on the image-side surface 32 of the first lens element 3, which is favorable for enlarging the field angle. The third lens element 5 has a positive refractive index, and the refractive index of the third lens element 5 is stronger than that of the other lens elements, which is helpful for mainly correcting various aberrations. The convex portion 422 of the image-side surface 42 of the second lens element 4 located in the vicinity of the circumference, the concave portion 511 of the object-side surface 51 of the third lens element 5 located in the vicinity of the optical axis I, the concave portion 621 of the image-side surface 62 of the fourth lens element 6 located in the vicinity of the optical axis I, and the convex portion 622 of the image-side surface 62 located in the vicinity of the circumference are matched to achieve the effect of improving the imaging quality. The position of the aperture 2 must be considered in consideration of the combination of many parameters such as the lens surface type, the lens thickness and the air gap between the lenses, and the characteristics of the above-mentioned lenses are considered in consideration of the optical characteristics and the lens length of the optical imaging lens 10, for example: the first lens element 3 with positive refractive index can effectively increase the light-gathering power, and the aperture stop 2 is disposed on the image-side surface 32 of the first lens element 3 to help enlarge the field of view, so the design of the position of the aperture stop 2 is of particular significance.

Second, the longitudinal spherical aberration, astigmatic aberration, and distortion of the embodiments of the present invention all conform to the usage specifications. In addition, the three kinds of off-axis light with red, green and blue representing wavelengths at different heights are all concentrated near the imaging point, and the deviation amplitude of each curve can show that the deviation of the imaging point of the off-axis light at different heights can be controlled, so that the spherical aberration, the aberration and the distortion suppression capability are good. Further referring to the imaging quality data, the distances between the three representative wavelengths of red, green and blue are also very close, showing that the present invention has good concentration of light of different wavelengths and excellent dispersion suppression capability in various states. That is, the present invention can generate excellent image quality by the design and mutual matching of the lenses.

Third, the above eight embodiments show the design of the optical imaging lens 10 of the present invention, and the system length of these embodiments can be reduced to less than 4.112mm, compared to the conventional optical imaging lens, the lens of the present invention can be used to manufacture thinner products, so that the present invention has economic benefits meeting the market requirements.

While the invention has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. An optical imaging lens sequentially comprises a first lens, an aperture, a second lens, a third lens and a fourth lens from an object side to an image side along an optical axis, wherein the first lens to the fourth lens respectively comprise an object side surface facing the object side and allowing imaging light to pass and an image side surface facing the image side and allowing the imaging light to pass;

the first lens element has positive refractive index;

the second lens element with refractive index has a convex surface at the periphery thereof;

the third lens element with positive refractive index has a concave surface portion on the object-side surface thereof in the region near the optical axis;

the fourth lens element with refractive index has a concave part at the region near the optical axis and a convex part at the region near the circumference;

the optical imaging lens has only four lenses with refractive index, the first lens has an abbe number v1, the second lens has an abbe number v2, the first lens has an optical thickness T1, the third lens has an optical thickness T3, an optical air gap between the first lens and the second lens is G12, an optical air gap between the second lens and the third lens is G23, the sum of the optical thicknesses of the first lens, the second lens, the third lens and the fourth lens is ALT, the sum of the optical thicknesses of the first lens, the second lens, the third lens and the fourth lens is Gaa, and the following conditions are satisfied: the | v1-v2| ≧ 25, (G12+ T3)/(T1+ G23) | 2.25, and ALT/Gaa ≥ 2.45.

2. The optical imaging lens of claim 1, wherein the system focal length of the optical imaging lens is EFL, and further satisfies the following conditional expression: EFL/ALT is more than or equal to 1.3.

3. The optical imaging lens of claim 2, wherein the fourth lens element has a thickness T4 on the optical axis, and further satisfies the following conditional expression: (T3+ T4)/G12 is not less than 2.4.

4. The optical imaging lens of claim 1, further satisfying the following conditional expressions: ALT/G12 is more than or equal to 3.6.

5. The optical imaging lens of claim 4, wherein the system focal length of the optical imaging lens is EFL, and further satisfies the following condition: EFL/ALT is more than or equal to 1.3.

6. The optical imaging lens of claim 1, wherein the second lens has a thickness T2 on the optical axis, and the fourth lens has a thickness T4 on the optical axis, and further satisfies the following conditional expressions: (T3+ T4)/(T1+ T2) is less than or equal to 2.05.

7. The optical imaging lens of claim 1, wherein an air gap between the third lens and the fourth lens on the optical axis is G34, and further satisfies the following conditional expression: ALT/(G23+ G34) is less than or equal to 12.45.

8. The optical imaging lens of claim 1, wherein an air gap between the third lens and the fourth lens on the optical axis is G34, and further satisfies the following conditional expression: T3/(G23+ G34) is less than or equal to 7.4.

9. The optical imaging lens of claim 1, wherein the second lens has a thickness T2 on the optical axis, and the fourth lens has a thickness T4 on the optical axis, and further satisfies the following conditional expressions: T4/T2 is less than or equal to 1.35.

10. The optical imaging lens of claim 1, wherein the fourth lens element has an abbe number v4, and further satisfies the following conditional expression: v1/v4 is more than or equal to 0.95 and less than or equal to 1.05.

11. An optical imaging lens sequentially comprises a first lens, an aperture, a second lens, a third lens and a fourth lens from an object side to an image side along an optical axis, wherein the first lens to the fourth lens respectively comprise an object side surface facing the object side and allowing imaging light to pass and an image side surface facing the image side and allowing the imaging light to pass;

the first lens element has positive refractive index;

the optical imaging lens has only four lenses with refractive index, the first lens has an abbe number v1, the second lens has an abbe number v2, the first lens has an optical thickness T1, the third lens has an optical thickness T3, an optical air gap between the first lens and the second lens is G12, an optical air gap between the second lens and the third lens is G23, the sum of three optical air gaps between the first lens and the fourth lens is Gaa, and the following conditions are satisfied: the | v1-v2| is more than or equal to 25, (G12+ T3)/(T1+ G23) is more than or equal to 2.25, and T3/Gaa is more than or equal to 1.2.

12. The optical imaging lens of claim 11, wherein the sum of the thicknesses of the first lens element, the second lens element, the third lens element and the fourth lens element on the optical axis is ALT, the system focal length of the optical imaging lens is EFL, and the following conditional expressions are further satisfied: EFL/ALT is more than or equal to 1.3.

13. The optical imaging lens of claim 12, wherein the fourth lens element has a thickness T4 on the optical axis, and further satisfies the following conditional expression: (T3+ T4)/G12 is not less than 2.4.

14. The optical imaging lens of claim 1, wherein an air gap between the third lens and the fourth lens on the optical axis is G34, and further satisfies the following conditional expression: T1/(G23+ G34) is less than or equal to 2.7.

15. The optical imaging lens of claim 14, wherein the fourth lens element has a thickness T4 on the optical axis, and further satisfies the following conditional expression: G12/T4 is less than or equal to 1.55.

16. The optical imaging lens of claim 11, wherein the second lens has a thickness T2 on the optical axis, and the fourth lens has a thickness T4 on the optical axis, and further satisfies the following conditional expressions: (T3+ T4)/(T1+ T2) is less than or equal to 2.05.

17. The optical imaging lens of claim 11, wherein an air gap between the third lens and the fourth lens on the optical axis is G34, and further satisfies the following conditional expression: ALT/(G23+ G34) is less than or equal to 12.45.

18. The optical imaging lens of claim 11, wherein an air gap between the third lens and the fourth lens on the optical axis is G34, and further satisfies the following conditional expression: T3/(G23+ G34) is less than or equal to 7.4.

19. The optical imaging lens of claim 11, wherein the second lens has a thickness T2 on the optical axis, and further satisfies the following conditional expression: G12/T2 is less than or equal to 2.

20. The optical imaging lens of claim 11, wherein the fourth lens element has an abbe number v4, and further satisfies the following conditional expression: v1/v4 is more than or equal to 0.95 and less than or equal to 1.05.