Patent Description:
In recent years, with advancements in portable electronic devices having camera functionalities, the demand for an optical image capturing system is raised gradually. The image sensing device of the ordinary photographing camera is commonly selected from a charge-coupled device (CCD) or a complementary metal-oxide-semiconductor sensor (CMOS Sensor). Besides, as advanced semiconductor manufacturing technology enables the minimization of the pixel size of the image sensing device, the development of the optical image capturing system towards the field of high pixels. Moreover, with the advancement in drones and driverless autonomous vehicles, Advanced Driver Assistance System (ADAS) plays an important role, collecting environmental information through various lenses and sensors to ensure the driving safety of the driver. Furthermore, as the image quality of the automotive lens changes with the temperature of an external application environment, the temperature requirements of the automotive lens also increase. Therefore, the requirement for high imaging quality is rapidly raised.

Good imaging lenses generally have the advantages of low distortion, high resolution, etc. In practice, small size and cost must be considered. Therefore, it is a big problem for designers to design a lens with good imaging quality under various constraints. Prior art can be found in <CIT>, <CIT>, <CIT> or <CIT>.

In view of the reasons mentioned above, the primary objective of the present invention is to provide an optical imaging lens that provides a better optical performance of high image quality and low distortion.

The present invention provides an optical imaging lens according to independent claim <NUM>. The dependent claims show further examples of the said optical imaging lens.

With the aforementioned design, the optical imaging lens of the present invention has two apertures, which could effectively improve a chromatic aberration of the optical imaging lens. In addition, the arrangement of the refractive powers and the conditions could achieve the effect of high image quality and low distortion.

The present invention will be best understood by referring to the following detailed description of some illustrative examples (not showing all features of claim <NUM>) e in conjunction with the accompanying drawings, in which.

An optical imaging lens <NUM> according to a first example(not showing all features of claim <NUM>) is illustrated in <FIG>, which includes, in order along an optical axis Z from an object side to an image side, a first optical assembly C1, a second optical assembly C2, a third optical assembly C3, a first aperture ST1, a fourth optical assembly C4, a fifth optical assembly C5, a second aperture ST2, a sixth optical assembly C6, and a seventh optical assembly C7. In the current example, one of the first optical assembly, the second optical assembly, the third optical assembly, the fourth optical assembly, the fifth optical assembly, the sixth optical assembly, and the seventh optical assembly C7 includes a compound lens with at least two lenses that are adhered, while the others are single lens.

The first optical assembly C1 has negative refractive power. In the current example, the first optical assembly C1 is a single lens that includes a first lens L1, wherein the first lens L1 is a negative meniscus, and an object-side surface S1 of the first lens L1 is a convex surface toward the object side, and an image-side surface S2 of the first lens L1 is a concave surface that is arc-shaped. As shown in <FIG>, a part of a surface of the first lens L1 toward the image side is recessed to form the image-side surface S2, and the optical axis Z passes through the object-side surface S1 and the image-side surface S2.

The second optical assembly C2 has negative refractive power. In the current example, the second optical assembly C2 is a single lens that includes a second lens L2, wherein the second lens L2 is a negative meniscus, and an object-side surface S3 of the second lens L2 is a convex surface that is slightly convex toward the object side, and an image-side surface S4 of the second lens L2 is a concave surface that is arc-shaped. The object-side surface S3 of the second lens L2, the image-side surface S4 of the second lens L2, or both of the object-side surface S3 and the image-side surface S4 of the second lens L2 are aspheric surfaces. As shown in <FIG>, in the current example, both of the object-side surface S3 and the image-side surface S4 of the second lens L2 are aspheric surfaces, wherein a part of a surface of the second lens L2 toward the image side is recessed to form the image-side surface S4, and the optical axis Z passes through the object-side surface S3 and the image-side surface S4.

The third optical assembly C3 has positive refractive power. In the current example, the third optical assembly C3 is a single lens that includes a third lens L3, wherein the third lens L3 is a biconvex lens (i.e., both of an object-side surface S5 of the third lens L3 and an image-side surface S6 of the third lens L3 are convex surfaces). As shown in <FIG>, the object-side surface S5 of the third lens L3 is slightly convex toward the object side, and the image-side surface S6 of the third lens L3 is convex toward the image side in an arc-shape.

The fourth optical assembly C4 has positive refractive power. In the current example, the fourth optical assembly C4 is a single lens that includes a fourth lens L4, wherein the fourth lens L4 is a biconvex lens (i.e., both of an object-side surface S7 of the fourth lens L4 and an image-side surface S8 of the fourth lens L4 are convex surfaces). As shown in <FIG>, the object-side surface S7 of the fourth lens L4 is convex toward the object side in an arc shape, and the image-side surface S8 of the fourth lens L4 is convex toward the image side in an arc-shape. In the current example, the first aperture ST1 is disposed between the third lens L3 of the third optical assembly C3 and the fourth lens L4 of the fourth optical assembly C4 and is closer to the object-side surface S7 of the fourth lens L4 than the image-side surface S6 of the third lens L3.

The fifth optical assembly C5 has positive refractive power. In the current example, the fifth optical assembly C5 is a compound lens formed by adhering a fifth lens L5 and a sixth lens L6, which could effectively improve a chromatic aberration of the optical imaging lens <NUM>. As shown in <FIG>, the fifth lens is a negative meniscus with negative refractive power, wherein an object-side surface S9 of the fifth lens L5 is a convex surface that is convex toward the object side in an arc-shape, and an image-side surface S10 of the fifth lens L5 is a concave surface that is arc-shaped. In the current example, a part of a surface of the fifth lens L5 toward the image side is recessed to form the image-side surface S10. The sixth lens L6 is a biconvex lens with positive refractive power (i.e., both of an object-side surface S11 of the sixth lens L6 and an image-side surface S12 of the sixth lens L6 are convex surfaces), wherein the object-side surface S11 of the sixth lens L6 and the image-side surface S10 of the fifth lens L5 are adhered and form a same surface.

The sixth optical assembly C6 has negative refractive power. In the current example, the sixth optical assembly C6 is a single lens that includes a seventh lens L7, wherein the seventh lens L7 is a negative meniscus; an object-side surface S13 of the seventh lens L7 is a concave surface, and an image-side surface S14 of the seventh lens L7 is a convex surface. As shown in <FIG>, a part of a surface of the seventh lens L7 toward the object side is recessed to form the object-side surface S13, and the image-side surface S14 of the seventh lens L7 is convex toward the image side in an arc-shape. In the current example, the second aperture ST2 is disposed between the sixth lens L6 of the fifth optical assembly C5 and the seventh lens L7 of the sixth optical assembly C6.

The seventh optical assembly C7 has positive refractive power. In the current example, the seventh optical assembly C7 is a single lens that includes an eighth lens L8, wherein the eighth lens L8 is a biconvex lens (i.e., both of an object-side surface S15 of the eighth lens L8 and an image-side surface S16 of the eighth lens L8 are convex surfaces). The object-side surface S15 of the eighth lens L8, the image-side surface S16 of the eighth lens L8, or both of the obj ect-side surface S15 and the image-side surface S16 of the eighth lens L8 are aspheric surfaces. As shown in <FIG>, in the current example, both of the object-side surface S15 and the image-side surface S16 of the eighth lens L8 are aspheric surfaces, wherein the object-side surface S15 of the eighth lens L8 is convex toward the object side in an arc-shape, and the image-side surface S16 of the eighth lens L8 is convex toward the image side in an arc-shape.

Additionally, the optical imaging lens <NUM> further includes an infrared filter L9 and a protective glass L10, wherein the infrared filter L9 is closer to the image-side surface S16 of the eighth lens L8 of the seventh optical assembly C7 than an image plane Im of the optical imaging lens <NUM> for filtering out excess infrared rays in an image light passing through the first optical assembly C1 to the seventh optical assembly C7 to improve an image quality. The protective glass L10 is disposed between the infrared filter L9 and the image plane Im for protecting the infrared filter L9.

In order to keep the optical imaging lens <NUM> in good optical performance and high imaging quality, the optical imaging lens <NUM> further satisfies:<MAT><MAT><MAT><MAT> <MAT><MAT><MAT><MAT>
wherein F is a focal length of the optical imaging lens <NUM>; f1 is a focal length of the first lens L1 of the first optical assembly C1; f2 is a focal length of the second lens L2 of the second optical assembly C2; f3 is a focal length of the third lens L3 of the third optical assembly C3; f4 is a focal length of the fourth lens L4 of the fourth optical assembly C4; f5 is a focal length of the fifth lens L5 of the fifth optical assembly C5; f6 is a focal length of the sixth lens L6 of the fifth optical assembly C5; f7 is a focal length of the seventh lens L7 of the sixth optical assembly C6; f8 is a focal length of the eighth lens L8 of the seventh optical assembly C7; f56 is a focal length of the fifth optical assembly C5; ftotal is a focal length of a combination of the first optical assembly C1 to the seventh optical assembly C7.

Parameters of the optical imaging lens <NUM> of the first example of the present invention are listed in following Table <NUM>, including the focal length F of the optical imaging lens <NUM> (also called an effective focal length (EFL)), a F-number (Fno), a maximal field of view (HFOV), a radius of curvature (R) of each lens, a distance (D) between each surface and the next surface on the optical axis Z, a refractive index (Nd) of each lens, the focal length of each lens, and the focal length (cemented focal length) of the fifth optical assembly C5, wherein a unit of the focal length, the radius of curvature, and the distance is millimeter (mm).

It can be seen from Table <NUM> that, in the current example, the focal length F of the optical imaging lens <NUM> is <NUM>, and the Fno is <NUM>, and the HFOV is <NUM> degrees, wherein f1=-<NUM>; f2=-<NUM>; f3=<NUM>; f4=<NUM>; f5=-<NUM>; f6=<NUM>; f7=-<NUM>; f8=<NUM>; f56=<NUM>.

Additionally, based on the above detailed parameters, detailed values of the aforementioned conditional formula in the first example are as follows: F/f1=-<NUM>; F/f2=-<NUM>; F/f3=<NUM>; F/f4=<NUM>; F/f56=<NUM>; F/f5=-<NUM>; F/f6=<NUM>; F/f7=-<NUM>; F/f8=<NUM>; F/ftotal=<NUM>.

With the aforementioned design, the first optical assembly C1 to the seventh optical assembly C7 satisfy the aforementioned conditions (<NUM>) to (<NUM>) of the optical imaging lens <NUM>.

Moreover, an aspheric surface contour shape Z of each of the object-side surface S3 of the second lens L2, the image-side surface S4 of the second lens L2, the object-side surface S15 of the eighth lens L8, and the image-side surface S16 of the eighth lens L8 of the optical imaging lens <NUM> according to the first example could be obtained by following formula: <MAT> wherein Z is aspheric surface contour shape; c is reciprocal of radius of curvature; h is half the off-axis height of the surface; k is conic constant; A2, A4, A6, A8, A10, A12, A14, and A16 respectively represents different order coefficient of h.

The conic constant k of each of the object-side surface S3 of the second lens L2, the image-side surface S4 of the second lens L2, the object-side surface S15 of the eighth lens L8, and the image-side surface S16 of the eighth lens L8 of the optical imaging lens <NUM> according to the first example and the different order coefficient of A2, A4, A6, A8, A10, A12, A14, and A16 are listed in following Table <NUM>:.

Taking optical simulation data to verify the imaging quality of the optical imaging lens <NUM>, wherein <FIG> a diagram showing the astigmatic field curves according to the first example; <FIG> is a diagram showing the distortion according to the first example; <FIG> is a diagram showing the modulus of the OTF according to the first example. In <FIG>, a curve S is data of a sagittal direction, and a curve T is data of a tangential direction. The graphics shown in <FIG> and <FIG> are within a standard range. In this way, the optical imaging lens <NUM> of the first example could effectively enhance image quality and lower a distortion thereof.

An optical imaging lens <NUM> according to a second example of the present invention is illustrated in <FIG>, which includes, in order along an optical axis Z from an object side to an image side, a first optical assembly C1, a second optical assembly C2, a third optical assembly C3, a first aperture ST1, a fourth optical assembly C4, a fifth optical assembly C5, a second aperture ST2, a sixth optical assembly C6, and a seventh optical assembly C7.

The second optical assembly C2 has negative refractive power. In the current example, the second optical assembly C2 is a single lens that includes a second lens L2, wherein the second lens L2 is a negative meniscus, and an object-side surface S3 of the second lens L2 is a convex surface that is slightly convex toward the object side, and an image-side surface S4 of the second lens L2 is a concave surface that is arc-shaped. As shown in <FIG>, in the current example, both of the object-side surface S3 and the image-side surface S4 of the second lens L2 are aspheric surfaces, wherein a part of a surface of the second lens L2 toward the image side is recessed to form the image-side surface S4, and the optical axis Z passes through the object-side surface S3 and the image-side surface S4.

The seventh optical assembly C7 has positive refractive power In the current example, the seventh optical assembly C7 is a single lens that includes an eighth lens L8, wherein the eighth lens L8 is a biconvex lens (i.e., both of an object-side surface S15 of the eighth lens L8 and an image-side surface S16 of the eighth lens L8 are convex surfaces). As shown in <FIG>, in the current example, both of the object-side surface S15 and the image-side surface S16 of the eighth lens L8 are aspheric surfaces, wherein the obj ect-side surface S15 of the eighth lens L8 is convex toward the object side in an arc-shape, and the image-side surface S16 of the eighth lens L8 is convex toward the image side in an arc-shape.

In order to keep the optical imaging lens <NUM> in good optical performance and high imaging quality, the optical imaging lens <NUM> further satisfies:<MAT><MAT><MAT><MAT><MAT><MAT><MAT><MAT>.

wherein F is a focal length of the optical imaging lens <NUM>; f1 is a focal length of the first lens L1 of the first optical assembly C1; f2 is a focal length of the second lens L2 of the second optical assembly C2; f3 is a focal length of the third lens L3 of the third optical assembly C3; f4 is a focal length of the fourth lens L4 of the fourth optical assembly C4; f5 is a focal length of the fifth lens L5 of the fifth optical assembly C5; f6 is a focal length of the sixth lens L6 of the fifth optical assembly C5; f7 is a focal length of the seventh lens L7 of the sixth optical assembly C6; f8 is a focal length of the eighth lens L8 of the seventh optical assembly C7; f56 is a focal length of the fifth optical assembly C5; ftotal is a focal length of a combination of the first optical assembly C1 to the seventh optical assembly C7.

Parameters of the optical imaging lens <NUM> of the second example of the present invention are listed in following Table <NUM>, including the focal length F of the optical imaging lens <NUM> (also called an effective focal length (EFL)), a F-number (Fno), a maximal field of view (HFOV), a radius of curvature (R) of each lens, a distance (D) between each surface and the next surface on the optical axis Z, a refractive index (Nd) of each lens, the focal length of each lens, and the focal length (cemented focal length) of the fifth optical assembly C5, wherein a unit of the focal length, the radius of curvature, and the distance is millimeter (mm).

It can be seen from Table <NUM> that, in the second example, the focal length (F) of the optical imaging lens <NUM> is <NUM>, and the Fno is <NUM>, and the HFOV is <NUM> degrees, wherein f1=-<NUM>; f2=-<NUM>; f3=<NUM>; f4=<NUM>; f5=-<NUM>; f6= <NUM>; f7=-<NUM>; f8=<NUM>; f56=<NUM>.

Additionally, based on the above detailed parameters, detailed values of the aforementioned conditional formula in the second example are as follows: F/f1=-<NUM>; F/f2=-<NUM>; F/f3=<NUM>; F/f4=<NUM>; F/f56=<NUM>; F/f5=-<NUM>; F/f6=<NUM>; F/f7=-<NUM>; F/f8=<NUM>; F/ftotal=<NUM>.

Moreover, an aspheric surface contour shape Z of each of the object-side surface S3 of the second lens L2, the image-side surface S4 of the second lens L2, the object-side surface S15 of the eighth lens L8, and the image-side surface S16 of the eighth lens L8 of the optical imaging lens <NUM> according to the second example could be obtained by following formula: <MAT> wherein Z is aspheric surface contour shape; c is reciprocal of radius of curvature; h is half the off-axis height of the surface; k is conic constant; A2, A4, A6, A8, A10, A12, A14, and A16 respectively represents different order coefficient of h.

The conic constant k of each of the object-side surface S3 of the second lens L2, the image-side surface S4 of the second lens L2, the object-side surface S15 of the eighth lens L8, and the image-side surface S16 of the eighth lens L8 of the optical imaging lens <NUM> according to the second example and the different order coefficient of A2, A4, A6, A8, A10, A12, A14, and A16 are listed in following Table <NUM>:.

Taking optical simulation data to verify the imaging quality of the optical imaging lens <NUM>, wherein <FIG> a diagram showing the astigmatic field curves according to the second example; <FIG> is a diagram showing the distortion according to the second example; <FIG> is a diagram showing the modulus of the OTF according to the second example. In <FIG>, a curve S is data of a sagittal direction, and a curve T is data of a tangential direction. The graphics shown in <FIG> and <FIG> are within a standard range. In this way, the optical imaging lens <NUM> of the second example could effectively enhance image quality and lower a distortion thereof.

An optical imaging lens <NUM> according to a third example of the present invention is illustrated in <FIG>, which includes, in order along an optical axis Z from an object side to an image side, a first optical assembly C1, a second optical assembly C2, a third optical assembly C3, a first aperture ST1, a fourth optical assembly C4, a fifth optical assembly C5, a second aperture ST2, a sixth optical assembly C6, and a seventh optical assembly C7.

The seventh optical assembly C7 has positive refractive power. In the current example, the seventh optical assembly C7 is a single lens that includes an eighth lens L8, wherein the eighth lens L8 is a biconvex lens (i.e., both of an object-side surface S15 of the eighth lens L8 and an image-side surface S16 of the eighth lens L8 are convex surfaces). As shown in <FIG>, in the current example, both of the object-side surface S15 and the image-side surface S16 of the eighth lens L8 are aspheric surfaces, wherein the object-side surface S15 of the eighth lens L8 is convex toward the object side in an arc-shape, and the image-side surface S16 of the eighth lens L8 is convex toward the image side in an arc-shape.

Parameters of the optical imaging lens <NUM> of the third example of the present invention are listed in following Table <NUM>, including the focal length F of the optical imaging lens <NUM> (also called an effective focal length (EFL)), a F-number (Fno), a maximal field of view (HFOV), a radius of curvature (R) of each lens, a distance (D) between each surface and the next surface on the optical axis Z, a refractive index (Nd) of each lens, the focal length of each lens, and the focal length (cemented focal length) of the fifth optical assembly C5, wherein a unit of the focal length, the radius of curvature, and the distance is millimeter (mm).

Moreover, an aspheric surface contour shape Z of each of the object-side surface S3 of the second lens L2, the image-side surface S4 of the second lens L2, the object-side surface S15 of the eighth lens L8, and the image-side surface S16 of the eighth lens L8 of the optical imaging lens <NUM> according to the third example could be obtained by following formula: <MAT> wherein Z is aspheric surface contour shape; c is reciprocal of radius of curvature; h is half the off-axis height of the surface; k is conic constant; A2, A4, A6, A8, A10, A12, A14, and A16 respectively represents different order coefficient of h.

The conic constant k of each of the object-side surface S3 of the second lens L2, the image-side surface S4 of the second lens L2, the object-side surface S15 of the eighth lens L8, and the image-side surface S16 of the eighth lens L8 of the optical imaging lens <NUM> according to the third example and the different order coefficient of A2, A4, A6, A8, A10, A12, A14, and A16 are listed in following Table <NUM>:.

Claim 1:
An optical imaging lens (<NUM>, <NUM>, <NUM>), in order from an object side to an image side along an optical axis, comprising:
a first lens (L1) having negative refractive power;
a second lens (L2) having negative refractive power;
a third lens (L3) having positive refractive power;
a fourth lens (L4) having positive refractive power;
a fifth lens (L5) having positive refractive power;
a sixth lens (L6) having negative refractive power;
a seventh lens (L7) having negative refractive power;
an eighth lens (L8) having positive refractive power;
wherein the optical imaging lens (<NUM>, <NUM>, <NUM>) has a total of the eight lenses with refractive power and comprises a compound lens formed by adhering the fifth lens (L5) and the sixth lens (L6), characterized in that a first aperture (ST1) is arranged between the third lens (L3) and the fourth lens (L4) and a second aperture (ST2) is arranged between the sixth lens (L6) and the seventh lens (L7).