Projection lens and vehicle lamp

Abstract

The invention provides a projection lens and a vehicle lamp, the projection lens comprises three lenses, the three lenses are a first lens, a second lens and a third lens which are sequentially arranged from an object plane to an image plane, the first lens and the third lens have negative focal power, and the second lens has positive focal power. Therefore, the structure can be simplified, the manufacturing cost and the assembly difficulty can be reduced, aberration in an optical system can be reduced, chromatic aberration can be eliminated, the definition can be improved, and the low-pigment requirements of illumination and projection can be met.

Description

Technical Field

[0001] The present application relates to the technical field of optical products, and particularly relates to a projection lens and a vehicle headlamp. Background Art

[0002] In recent years, vehicle headlamp lighting modules have been rapidly updated with the development of technology. However, most front headlamp modules are composed of a cut-off line structure, a reflector bowl, and a convex lens. This traditional lighting system has a low light efficiency utilization rate and only has a lighting function, unable to meet people's entertainment needs. And the million-pixel headlamp has already become one of the industry development trends.

[0003] In the prior art, most optical projection lenses of automotive front headlamps use a combination of four or more lenses, resulting in a relatively large module volume, complex structure, and high cost. Moreover, when the number of lenses of the optical projection lens exceeds four, both the manufacturing cost and the assembly difficulty will increase, which is not conducive to the styling design. Summary of the Invention

[0004] In view of this, the present application provides a projection lens and a vehicle headlamp, which have a simple structure, low cost, and can meet the requirements of lighting and projection.

[0005] In order to achieve the above object, the present application provides the following technical solutions:

[0006] A projection lens, which is applied to a vehicle headlamp, includes three lenses. The three lenses are a first lens, a second lens, and a third lens arranged in sequence from the object plane to the image plane. The first lens and the third lens have negative optical powers, and the second lens has a positive optical power.

[0007] Optionally, the first lens has a first light incident surface that is convex and a first light exiting surface that is concave; the second lens has a second light incident surface that is convex and a second light exiting surface that is convex; the third lens has a third light incident surface that is convex and a third light exiting surface that is concave.

[0008] Optionally, an aperture stop is provided on the first lens, and the aperture stop surrounds the outer periphery of the first light exiting surface.

[0009] Optionally, the aperture stop is formed on the side surface of the first lens close to the second lens.

[0010] Optionally, among the first light incident surface, the first light exiting surface, the second light incident surface, the second light exiting surface, the third light exiting surface, and the third light incident surface, a part is set as an aspherical surface and another part is set as a spherical surface.

[0011] Optionally, the expression of the aspherical surface is z = cr^2 / (1 + √(1 - (1 + k)c^2r^2)) + Ar^4 + Br^6, where z is the sag height at the r position on the aspherical surface, c is the paraxial curvature of the aspherical surface, c = 1 / R, R is the radius of curvature, k is the conic coefficient, and A and B are the coefficients of the high-order terms.

[0012] Optionally, the central interval between the first light-emitting surface and the second light-incident surface is D12, and the central interval between the second light-emitting surface and the third light-incident surface is D23, satisfying D12 > D23 and D23 > 0.5 mm.

[0013] Optionally, the radius of curvature of the first light-incident surface is R1, and the radius of curvature of the first light-emitting surface is R2, satisfying |R1| > |R2| and R1 > 40 mm; the radius of curvature of the third light-incident surface is R5, and the radius of curvature of the third light-emitting surface is R6, satisfying |R5| < |R6|.

[0014] Optionally, the refractive index of the third lens is greater than 1.8.

[0015] Optionally, the equivalent focal length of the projection lens is f0, the equivalent focal length of the first lens is f1, the equivalent focal length of the second lens is f2, and the equivalent focal length of the third lens is f3, satisfying f1 > f2 > f0 > f3, |f1 - f2| > 40 mm, and |f2 - f3| > 5 mm.

[0016] Optionally, the refractive index of the first lens is n1, and the Abbe number of the first lens is Vd1; the refractive index of the second lens is n2, and the Abbe number of the second lens is Vd2; the refractive index of the third lens is n3, and the Abbe number of the third lens is Vd3; satisfying n3 > n1 > n2, n1 > 1.4, n2 > 1.5, n3 > 1.8, and satisfying Vd2 - Vd1 > 25 and Vd2 - Vd3 > 25.

[0017] A vehicle headlight includes the projection lens as described in any one of the above.

[0018] The projection lens and the vehicle headlight provided in this application have only three lenses, which can simplify the structure, reduce the manufacturing cost and the assembly difficulty. Moreover, by using the difference in optical power between the first lens and the second lens, and the difference in optical power between the second lens and the third lens, a double-separated lens group or a double-cemented lens group can be combined, which can reduce the aberration in the optical system, eliminate chromatic aberration, improve the clarity, and meet the low-color requirements of lighting and projection. Description of the Drawings

[0019] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings.

[0020] Figure 1 Cross-sectional view of a projection lens shown for some embodiments;

[0021] Figure 2 Optical path schematic diagram of a projection lens shown for some embodiments;

[0022] Figure 3 MTF curve graph of a projection lens shown for some embodiments;

[0023] Figure 4 Spot diagram of a projection lens shown for some embodiments;

[0024] Figure 5 Field curvature and distortion curve graph of a projection lens shown for some embodiments;

[0025] Figure 6 Vertical aberration diagram of a projection lens shown for some embodiments.

[0026] Explanation of reference numerals: 10, the first lens; 11, the first light incident surface; 12, the first light exit surface; 13, the aperture stop; 20, the second lens; 21, the second light incident surface; 22, the second light exit surface; 30, the third lens; 31, the third light incident surface; 32, the third light exit surface; 40, the image plane. Detailed implementation manners

[0027] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0028] Such as Figures 1 - 6As shown in the figure, an embodiment of the present application provides a projection lens, which is applied to vehicle headlights, specifically, it can be applied to automotive headlights. For example, the projection lens is suitable for white light LED light sources with thousands or tens of thousands of pixels in the vehicle lighting industry. The white light LED light source with thousands or tens of thousands of pixels means that there are thousands of tiny white light LED light-emitting chips (the chip size is in the micron range) on one LED, and each white light LED light-emitting chip can be independently controlled for turning on and off and brightness adjustment. Through the pixel white light LED light source, the information of the large light pattern to be illuminated (such as the intensity distribution of high beam or low beam) can be pixelated (here, the number of pixels of the large light pattern is not greater than the number of white light LED light-emitting chips), so that the pixelated intensity distribution information corresponds one-to-one with the light-emitting state of the LED light-emitting chips. Then, the light-emitting state of the LED light-emitting chips is projected through the projection lens, and finally the large light intensity distribution information formed by the state of the LED light-emitting chips is formed on the road surface, and the brightness can be modulated by the pulse width.

[0029] The projection lens includes three lenses, which are arranged in sequence from the object side to the image side, so that the light on the object side can pass through the three lenses in sequence and irradiate on the corresponding area on the image side. Here, the projection lens has only three lenses, which can simplify the structure, reduce the manufacturing cost and assembly difficulty.

[0030] Among them, the three lenses are the first lens 10, the second lens 20 and the third lens 30 respectively. The first lens 10, the second lens 20 and the third lens 30 are arranged in sequence along the direction from the object surface to the image surface 40, that is, the second lens 20 is located between the first lens 10 and the third lens 30. The first lens 10 is close to the object surface, and the second lens 20 is close to the image surface 40, so that the light emitted from the object surface can pass through the first lens 10, the second lens 20 and the third lens 30 in sequence, and finally irradiate on the image surface 40.

[0031] It should be noted that during the design, multiple parallel lights at different angles need to irradiate the projection lens, and an image surface 40 is formed after passing through the projection lens. As Figure 2 shown, during the design, the object surface is on the left side, the image surface 40 is on the right side, and the light passes through the first lens 10, the second lens 20 and the third lens 30 from left to right in sequence. During the product application process, the object surface and the image surface are swapped, the object surface is on the right side, the image surface is on the left side, and the light passes through the third lens 30, the second lens 20 and the first lens 10 from right to left in sequence. The image surface and the object surface mentioned in this article refer to the image surface and the object surface during the design.

[0032] Moreover, the first lens 10 and the third lens 30 have negative optical powers, and the second lens 20 has a positive optical power, so that the first lens 10, the second lens 20, and the third lens 30 form a negative-positive-negative optical power form. In this way, by utilizing the difference in optical power between the first lens 10 and the second lens 20, and the difference in optical power between the second lens 20 and the third lens 30, a double-separated lens group or a double-cemented lens group can be combined, which can reduce the aberration in the optical system, eliminate chromatic aberration, improve clarity, and meet the low-colorant requirements for illumination and projection.

[0033] In a specific solution, the first lens 10 has a first light incident surface 11 that is convex and a first light exit surface 12 that is concave. Through the structural design of the first light exit surface 12 and the first light incident surface 11, the first lens 10 has a negative optical power. The second lens 20 has a second light incident surface 21 that is convex and a second light exit surface 22 that is convex. Through the structural design of the second light exit surface 22 and the second light incident surface 21, the second lens 20 has a positive optical power. The third lens 30 has a third light incident surface 31 that is convex and a third light exit surface 32 that is concave. Through the structural design of the third light exit surface 32 and the third light incident surface 31, the third lens 30 has a negative optical power.

[0034] During application, light rays sequentially pass through the third lens 30, the second lens 20, and the first lens 10. The third light incident surface 31 of the third lens 30 can diverge the light rays, and the second light exit surface 22 of the second lens 20 can converge the light rays, thereby enabling more light rays to enter the second lens 20, which is beneficial to improving the light efficiency and reducing aberration. The combination of the second light incident surface 21 of the second lens 20 and the first light exit surface 12 of the first lens 10 forms a double-cemented lens group or a double-separated lens group, which can further reduce chromatic aberration and aberration and enhance the light rays. In this way, by adopting a negative-positive-negative optical power form for the three lenses, it is beneficial to meet the overall requirements of high illumination brightness, good imaging quality, simple and stable lens structure, and low cost, and can achieve the purpose of cost reduction and efficiency improvement.

[0035] The materials of the three lenses can be set as PC (Polycarbonate) material, PMMA (Polymethyl methacrylate) material, resin material, or glass material. In a preferred solution, the first lens 10 and the second lens 20 are set as resin materials, and the third lens 30 is set as glass material.

[0036] In this solution, the projection lens includes an aperture stop 13. The aperture stop 13 is disposed on the first lens 10 and surrounds the outer periphery of the first light-emitting surface 12. The aperture stop 13 functions to block light. The amount of incident light and the amount of outgoing light can be controlled through the aperture stop 13 and balanced by the aperture stop 13, which is beneficial to achieving high brightness and high definition simultaneously. Moreover, the aperture stop 13 can control the light-emitting aperture of the first lens 10 to be applicable to a narrow-aperture (less than 20 mm) illumination module.

[0037] Among them, the aperture stop 13 is formed on the side of the first lens 10 close to the second lens 20. Specifically, the side of the first lens 10 close to the second lens 20 has a concave surface and a flat surface. The concave surface forms the first light-emitting surface 12, and the flat surface surrounds the outer periphery of the concave surface and forms the aperture stop 13. By integrating the aperture stop 13 on the first lens 10, the number of components can be reduced, the assembly error can be reduced, which is beneficial to reducing costs and improving product accuracy.

[0038] In some embodiments, among the first light-incident surface 11, the first light-emitting surface 12, the second light-incident surface 21, the second light-emitting surface 22, the third light-emitting surface 32, and the third light-incident surface 31, a part is set as an aspherical surface, and the other part is set as a spherical surface. In this way, by setting the aspherical surface, various-order aberrations can be reduced and the clarity can be improved. Since only a part is set as an aspherical surface, the manufacturing cost and the manufacturing difficulty can be reduced.

[0039] In a specific solution, the first light-incident surface 11, the first light-emitting surface 12, the second light-incident surface 21, and the second light-emitting surface 22 are set as aspherical surfaces. Correspondingly, the third light-emitting surface 32 and the third light-incident surface 31 are set as spherical surfaces.

[0040] Among them, in the above-mentioned aspherical surface, the number of high-order terms in the expression of the aspherical surface is small, which can further reduce the manufacturing cost and the manufacturing difficulty. The expression of the aspherical surface is where z is the sag height at the r position on the aspherical surface, c is the paraxial curvature of the aspherical surface, c = 1 / R, R is the radius of curvature, k is the conic coefficient, and A and B are the coefficients of the high-order terms. Here, in the expression of the aspherical surface, the high-order terms have only A and B, and the number of high-order terms is small, which is not only convenient for processing and manufacturing, but also can reduce chromatic aberration and improve clarity.

[0041] It should be noted that the complete expression of this aspherical surface is as follows:

[0042]

[0043] where z is the sag height at the r position on the aspherical surface, c is the paraxial curvature of the aspherical surface, c = 1 / R, R is the radius of curvature, k is the conic coefficient, and A - J are the coefficients of the high-order terms. Specifically, the parameters of the above-mentioned aspherical surfaces are as follows in the table:

[0044]

[0045] In addition, the refractive index of the third lens 30 is greater than 1.8, so that the incident angle of light on the image plane can be effectively reduced, thereby improving the light efficiency utilization rate.

[0046] In some embodiments, the central interval between the first light-emitting surface 12 and the second light-incident surface 21 is D12, and the central interval between the second light-emitting surface 22 and the third light-incident surface 31 is D23, satisfying D12 > D23 and D23 > 0.5 mm. Here, the intermediate interval refers to the distance between the center of one surface and the center of the other. Since the centers of each surface are on the same axis, this central interval is a distance on this axis.

[0047] Since D23 > 0.5 mm and D12 > 0.5 mm, a double-separated lens group is formed between the first light-emitting surface 12 and the second light-emitting surface 22. Compared with a double-cemented lens group, the double-separated lens group is easier to process and manufacture, which is beneficial to cost savings. Moreover, since D12 > D23 and the aperture stop 13 is disposed on the first lens 10, the position of the aperture stop 13 can be easily adjusted, so that the adjustment effect of the aperture stop 13 is better, which is beneficial to ensuring better clarity and light efficiency.

[0048] The equivalent focal length of the projection lens is f0, the equivalent focal length of the first lens 10 is f1, the equivalent focal length of the second lens 20 is f2, and the equivalent focal length of the third lens 30 is f3, satisfying f1 > f2 > f0 > f3, |f1 - f2| > 40 mm, and |f2 - f3| > 5 mm. In this way, the field of view (FOV) is controlled by the equivalent focal lengths of the respective lenses so that the field of view meets the design requirements.

[0049] The radius of curvature of the first light-incident surface 11 is R1, and the radius of curvature of the first light-emitting surface 12 is R2, satisfying |R1| > |R2| and R1 > 40 mm; the radius of curvature of the third light-incident surface 31 is R5, and the radius of curvature of the third light-emitting surface 32 is R6, satisfying |R5| < |R6|. In a specific solution, the radius of curvature of the first light-incident surface 11 is set to 45 mm, the radius of curvature of the first light-emitting surface 12 is set to 17 mm, the radius of curvature of the third light-incident surface 31 is set to 14.52 mm, and the radius of curvature of the third light-emitting surface 32 is set to 17.257 mm. Through the design of the radius of curvature, the product can meet the design requirements.

[0050] The refractive index of the first lens 10 is n1, and the Abbe number of the first lens 10 is Vd1; the refractive index of the second lens 20 is n2, and the Abbe number of the second lens 20 is Vd2; the refractive index of the third lens 30 is n3, and the Abbe number of the third lens 30 is Vd3; it satisfies n3 > n1 > n2, n1 > 1.4, n2 > 1.5, n3 > 1.8, and satisfies Vd2 - Vd1 > 25, Vd2 - Vd3 > 25. For example, the refractive index of the first lens 10 is 1.59, and the Abbe number of the first lens 10 is 29.9; the refractive index of the second lens 20 is 1.49, and the Abbe number of the second lens 20 is 57.4; the refractive index of the third lens 30 is 2, and the Abbe number of the third lens 30 is 28.3. Through the design of the refractive index and Abbe number of each lens, the product can meet the design requirements.

[0051] The following specifically describes this projection lens in combination with the above embodiments.

[0052] The design requirement parameters of the projection lens are as follows in the table:

[0053]

[0054] According to the design requirement parameters of the projection lens, the parameters of the three lenses (the first lens 10, the second lens 20, and the third lens 30) are designed as follows in the table:

[0055] Surface type Radius of curvature (mm) Thickness (mm) Refractive index (Nd) Abbe number (Vd) Aperture (mm) Object surface Infinity Infinity First light entrance surface 45 12.336 1.59 29.9 16.53 First light exit surface 37.514 3.149 13.257 Second light entrance surface 12.608 22.084 1.49 57.4 18.304 Second light exit surface -25.647 0.498 16.647 Third light entrance surface 14.52 7.542 2 28.3 10.632 Third light exit surface 17.257 2.5 7.045 Image surface Infinity 7.129

[0056] According to the parameter design of the three lenses, tests are carried out, and the aberration analysis curves of this projection lens obtained are as Figures 3 - 6 shown, and the RMS radius and GEO radius of each field of view are as follows in the table.

[0057] Filed 1 2 3 4 5 RMS radius 47.390 52.292 67.573 95.423 173.447 GEO radius 84.915 130.33 160.078 219.760 330.796

[0058] The embodiment of the present application provides a vehicle lamp, including the projection lens in the above embodiment. With this setting, the projection lens has only three lenses, which can simplify the structure, reduce the manufacturing cost and assembly difficulty. Moreover, by using the difference in optical power between the first lens 10 and the second lens 20, and the difference in optical power between the second lens 20 and the third lens 30, a double-separated lens group or a double-cemented lens group can be combined, which can reduce the aberration in the optical system, eliminate chromatic aberration, improve clarity, and meet the low chromaticity requirements for lighting and projection.

[0059] The basic principles of the present application have been described above in connection with specific embodiments. However, it should be noted that the advantages, benefits, effects, etc. mentioned in the present application are only examples and not limitations, and it cannot be considered that these advantages, benefits, effects, etc. are essential for each embodiment of the present application. Additionally, the specific details disclosed above are only for illustrative and facilitating understanding purposes and not limitations, and these details do not limit the present application to necessarily implementing with the above specific details.

[0060] The block diagrams of the devices, apparatuses, equipment, and systems involved in the present application are only illustrative examples and do not intend to require or imply that they must be connected, arranged, and configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, apparatuses, equipment, and systems can be connected, arranged, and configured in any manner. Words such as "including", "comprising", "having", etc. are open-ended terms, meaning "including but not limited to", and can be used interchangeably with each other. The word "or" and "and" used herein refer to the word "and / or" and can be used interchangeably with it, unless the context clearly indicates otherwise. The word "such as" used herein refers to the phrase "such as but not limited to" and can be used interchangeably with it.

[0061] It should also be noted that in the devices, equipment, and methods of the present application, each component or each step can be decomposed and / or recombined. These decompositions and / or recombinations should be regarded as equivalent solutions of the present application.

[0062] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present application. Various modifications to these aspects are very obvious to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of the present application. Therefore, the present application is not intended to be limited to the aspects shown herein, but rather to the broadest scope consistent with the principles and novel features disclosed herein.

[0063] It should be understood that the qualifiers "first", "second", "third", "fourth", "fifth", and "sixth" used in the description of the embodiments of the present application are only for more clearly elaborating the technical solutions and cannot be used to limit the protection scope of the present application.

[0064] The above description has been given for purposes of illustration and description. Additionally, this description does not intend to limit the embodiments of the present application to the forms disclosed herein. Although multiple example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, changes, additions, and sub-combinations thereof.

Claims

1. A projection lens, applied to a vehicle lamp, characterized in that: The invention comprises three lenses, wherein the three lenses are a first lens (10), a second lens (20) and a third lens (30) arranged in sequence from an object plane to an image plane (40); the first lens (10) and the third lens (30) have negative optical power, and the second lens (20) has positive optical power.

2. The projection lens according to claim 1, characterized in that: The first lens (10) has a convex first light-incoming surface (11) and a concave first light-emitting surface (12); the second lens (20) has a convex second light-incoming surface (21) and a convex second light-emitting surface (22); and the third lens (30) has a convex third light-incoming surface (31) and a concave third light-emitting surface (32).

3. The projection lens according to claim 2, characterized in that: An aperture stop (13) is provided on the first lens (10), and the aperture stop (13) surrounds the outer periphery of the first light exit surface (12).

4. The projection lens according to claim 3, characterized in that: The aperture stop (13) is formed on a side surface of the first lens (10) close to the second lens (20).

5. The projection lens according to claim 2, characterized in that: Among the first light incident surface (11), the first light emitting surface (12), the second light incident surface (21), the second light emitting surface (22), the third light emitting surface (32) and the third light incident surface (31), one part is set as an aspherical surface and the other part is set as a spherical surface.

6. The projection lens according to claim 5, characterized in that: The expression of the aspherical surface is z=cr^2 / (1+√(1―(1+k)c^2r^2))+Ar^4+Br^6, where z is the vector height at position r on the aspherical surface, c is the paraxial curvature of the aspherical surface, c=1 / R, R is the radius of curvature, k is the cone coefficient, and A and B are high-order coefficients.

7. The projection lens according to claim 2, wherein: The center distance between the first light emitting surface (12) and the second light incident surface (21) is D12, and the center distance between the second light emitting surface (22) and the third light incident surface (31) is D23, satisfying D12>D23, D23>0.5 mm.

8. The projection lens according to claim 2, wherein: The first light incident surface (11) has a curvature radius of R1, and the first light emitting surface (12) has a curvature radius of R2, satisfying |R1|>|R2|, R1>40 mm; the third light incident surface (31) has a curvature radius of R5, and the third light emitting surface (32) has a curvature radius of R6, satisfying |R5|<|R6|.

9. The projection lens according to claim 1, wherein: The refractive index of the third lens (30) is greater than 1.

8.

10. The projection lens according to claim 1, wherein: The equivalent focal length of the projection lens is f0, the equivalent focal length of the first lens (10) is f1, the equivalent focal length of the second lens (20) is f2, and the equivalent focal length of the third lens (30) is f3, satisfying f1>f2>f0>f3, |f1-f2|>40 mm, |f2-f3|>5 mm.

11. The projection lens according to claim 1, wherein: The refractive index of the first lens (10) is n1, and the Abbe number of the first lens (10) is Vd1; the refractive index of the second lens (20) is n2, and the Abbe number of the second lens (20) is Vd2; the refractive index of the third lens (30) is n3, and the Abbe number of the third lens (30) is Vd3; n3>n1>n2, n1>1.4, n2>1.5, n3>1.8, and Vd2-Vd1>25, Vd2-Vd3>25 are satisfied.

12. A vehicle lamp, characterized in that: The invention comprises the projection lens as claimed in any one of claims 1 to 11.

Images