A five-element optical lens with high brightness and small chromatic aberration

Abstract

The present invention discloses a five-piece optical lens with high brightness and low chromatic aberration. The lens is composed of a first lens, an aperture, a second lens, a third lens, a fourth lens, and a fifth lens in order from the object side to the image side along the optical axis. The fourth lens and the fifth lens form a lens group. The first lens has positive focal power, and both the object side and the image side are convex. The second lens has negative focal power, and the image side is concave. The third lens has positive focal power, and both the object side and the image side are convex. The fourth lens is configured as a meniscus lens with negative focal power and curved toward the image side. The fifth lens has positive focal power, and the object side is convex. By increasing the numerical aperture, the light energy utilization rate is improved, the brightness is increased, and the lens has good thermal stability.

Description

Technical Field

[0001] The present invention relates to the technical field of optical imaging display, and in particular discloses a five-piece optical lens with high brightness and small chromatic aberration. Background Art

[0002] Newly developed pixel headlights, also known as matrix headlights, utilize digital light projection technology, extending their functionality beyond illumination. They can also project patterns onto the ground, displaying weather conditions, road navigation, or other symbols for pedestrians and other vehicles to identify, acting as a kind of visual language. The optical system for pixel headlights requires luminous pixels—such as mini LEDs, microLEDs, LCD screens, LCOS, or illuminated DMD digital micromirrors—and projection optics. To ensure the projected pattern is clearly visible, the lens must achieve excellent optical performance, eliminating various optical aberrations such as chromatic aberration, field curvature, and astigmatism. Generally, a good optical lens utilizes a combination of multiple positive and negative lenses to eliminate these aberrations. The specific number of optical lenses used depends on the optical system's parameters, performance indicators, and the optical materials and processes used. More complex optical systems can include up to 10 lenses.

[0003] Pixel headlights combine lighting and imaging functions, requiring higher energy efficiency and brightness. Furthermore, high-quality products demand high image quality, particularly low color deviation. Furthermore, due to the unique characteristics of automotive applications, they require higher thermal and vibration reliability, lighter weight (due to weight reduction), and lower costs to remain competitive in the market.

[0004] Current lens designs either use more lenses, or use more expensive optical glass materials, or have low light energy utilization, or low imaging quality. For example, Chinese application publication number CN117434684A, with an authorization announcement date of January 23, 2024, discloses an optical imaging lens for high-definition projection technology for automotive headlights, comprising a first spherical glass lens, a second spherical glass lens, a third spherical glass lens, a fourth spherical glass lens, a fifth spherical glass lens, a sixth spherical glass lens, and a seventh spherical glass lens, which are arranged in sequence along the same optical axis from the image side to the object side; the aperture stop of the optical imaging lens is placed between the image side and the first spherical glass lens, the first spherical glass lens is a positive lens, the second spherical glass lens is a negative lens, the third spherical glass lens is a positive lens, the fourth spherical glass lens is a negative lens, the fifth spherical glass lens is a positive lens, the sixth spherical glass lens is a positive lens, and the seventh spherical glass lens is a meniscus lens. This optical imaging lens can ensure the vehicle's clear imaging quality in both high and low beam states, high lighting brightness, and various high-pixel graphic interaction requirements. In summary, as an application of pixel headlights, it must have high energy utilization, that is, a larger numerical aperture, and relatively stable performance under different operating temperatures (-45℃~+85℃). Based on the above discussion, we know that as an application of pixel headlights, it must have high energy utilization, small chromatic aberration, and high image quality resolution. In view of the above situation, it is urgent to solve. Summary of the Invention

[0005] Based on this, it is necessary to provide a five-piece optical lens with high brightness and small chromatic aberration to address the existing technical problems. It can be used in the projection system of smart pixel headlights such as automobile and motorcycle headlights to improve the utilization rate of light energy and brightness by increasing the numerical aperture, and it has good thermal stability.

[0006] To solve the problems of the prior art, the present invention discloses a five-piece optical lens with high brightness and low chromatic aberration, which is composed of a first lens, an aperture, a second lens, a third lens, a fourth lens, and a fifth lens in order from the object side to the image side along the optical axis; the fourth lens and the fifth lens form a lens group; the first lens has positive focal power, and both the object side and the image side are convex; the second lens has negative focal power, and the image side is concave; the third lens has positive focal power, and both the object side and the image side are convex; the fourth lens is configured as a meniscus lens with negative focal power and curved toward the image side; the fifth lens has positive focal power, and the object side is convex; and the lens satisfies the following conditional formula:

[0007] |R4|<|R3|, where R3 is the radius of curvature of the object side of the second lens, and R4 is the radius of curvature of the image side of the second lens;

[0008] f45>f1, f45>|f2|, f45>f3, where f3 is the equivalent focal length of the third lens, f1 is the equivalent focal length of the first lens, f2 is the equivalent focal length of the second lens, and f45 is the equivalent focal length of the fourth lens and the fifth lens combination;

[0009] |R9| / |R10|<1.2, where R9 is the radius of curvature of the object side of the fifth lens, and R10 is the radius of curvature of the image side of the fifth lens;

[0010] |f12| / f>6, f12 is the equivalent focal length of the combined lens system of the first lens and the second lens, f is the equivalent focal length of the system; OAL / f<2.6, where OAL is the total working length of the system;

[0011] D1 / OAL>0.6, D1 is the optical aperture of the first lens.

[0012] Preferably, at least a portion of the object side surface of the second lens is curved toward the image side surface.

[0013] Preferably, the back focus of the five-piece optical lens is greater than 2 mm.

[0014] Preferably, the optical surfaces of the first lens, the second lens, the third lens, the fourth lens and the fifth lens are all set to be aspherical surfaces.

[0015] Preferably, the fourth lens and the fifth lens are configured as a composite lens.

[0016] The beneficial effects of the present invention are: compared with ordinary lenses, it can significantly improve the energy utilization rate of pixel headlights, reduce chromatic aberration, and improve image quality resolution;

[0017] 1. The fourth lens and the fifth lens form a lens group, which is beneficial to reduce chromatic aberration, and helps to reduce field and spherical aberration;

[0018] 2. At least a portion of the object-side surface of the second lens is curved toward the image-side surface, which helps reduce Petzval field curvature and improve clarity.

[0019] 3. The conditions f45>f1, f45>|f2|, f45>f3 are met, so that the fifth lens is more used to modulate the light of the large field of view, while the impact on the central field of view is relatively small;

[0020] 4. The conditional formula |R9| / |R10|<1.2 is met. This constraint indicates that the image side surface of the fifth lens is relatively flat, which is conducive to guiding large-angle light into the optical lens;

[0021] 5. The condition |f12| / f>6 is met. This constraint limits the optical power of the first and second lenses in the system to a smaller value, which is beneficial for improving image quality. Furthermore, when the first and second lenses are made of plastic lenses, and the third, fourth, and fifth lenses are made of glass lenses, it helps improve the optical performance stability of the lenses under different temperature environments.

[0022] 6. The condition OAL / f < 2.6 is met. This constraint allows the system to have a smaller space requirement at the same optical power.

[0023] 7. Meeting the condition D1 / OAL>0.6 is beneficial to reducing the axial size of the system while increasing optical energy efficiency;

[0024] 8. The back focus distance of the five-element optical lens is greater than 2mm, maintaining the minimum gap to prevent interference between the lens and the imaging surface of the light source;

[0025] 9. The fourth lens and the fifth lens are configured as a composite lens. The composite lens is easier to assemble and also helps to reduce interface energy loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a structural diagram of embodiment 1 of the present invention.

[0027] Figure 2 This is an MTF curve diagram of Example 1 of the present invention.

[0028] Figure 3 This is the magnification chromatic aberration curve of Example 1 of the present invention.

[0029] Figure 4 This is a structural diagram of embodiment 2 of the present invention.

[0030] Figure 5 This is the MTF curve diagram of the second embodiment of the present invention.

[0031] Figure 6 This is the magnification chromatic aberration curve of Example 2 of the present invention.

[0032] Reference numerals are: a first lens 11 , an aperture 10 , a second lens 12 , a third lens 13 , a fourth lens 14 , and a fifth lens 15 . DETAILED DESCRIPTION

[0033] In order to further understand the features, technical means, specific objectives and functions achieved by the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] refer to Figures 1 to 6 .

[0035] The basic embodiment of the present invention discloses a five-element optical lens with high brightness and low chromatic aberration. The lens is composed of a first lens 11, an aperture 10, a second lens 12, a third lens 13, a fourth lens 14, and a fifth lens 15 in order from the object side to the image side along the optical axis. The fourth lens 14 and the fifth lens 15 form a lens group, which is beneficial for reducing chromatic aberration, field aberration, and spherical aberration.

[0036] The first lens 11 has positive refractive power and both the object-side surface and the image-side surface are convex;

[0037] The second lens element 12 has negative optical power and a concave image-side surface. At least a portion of the object-side surface of the second lens element 12 is curved toward the image-side surface, which helps to reduce Petzval field curvature.

[0038] The third lens 13 has positive refractive power and both the object-side surface and the image-side surface are convex;

[0039] The fourth lens 14 is configured as a meniscus lens having negative optical power and curved toward the image side;

[0040] The fifth lens element 15 has positive refractive power and a convex object-side surface.

[0041] And it satisfies the following conditions:

[0042] |R4|<|R3|, where R3 is the radius of curvature of the object side surface of the second lens 12, and R4 is the radius of curvature of the image side surface of the second lens 12;

[0043] f45>f1, f45>|f2|, f45>f3, where f3 is the equivalent focal length of the third lens 13, f1 is the equivalent focal length of the first lens 11, f2 is the equivalent focal length of the second lens 12, and f45 is the equivalent focal length of the fourth lens 14 and the fifth lens 15 combined. This allows the fifth lens to be used more to modulate light in a large field of view, while having relatively little effect on the central field of view.

[0044] |R9| / |R10|<1.2, where R9 is the radius of curvature of the object side surface of the fifth lens element 15, and R10 is the radius of curvature of the image side surface of the fifth lens element 15. This constraint indicates that the image side surface of the fifth lens element is relatively flat, which is conducive to guiding large-angle light into the optical lens;

[0045] |f12| / f>6, where f12 is the equivalent focal length of the combined lens group of the first lens 11 and the second lens 12, and f is the equivalent focal length of the system. This constraint limits the optical power of the first lens and the second lens in the system to a smaller value, which is beneficial for improving image quality. Moreover, when the first and second lenses are made of plastic lenses, and the third, fourth, and fifth lenses are made of glass lenses, it is beneficial for improving the optical performance stability of the lenses under different temperature environments.

[0046] OAL / f<2.6, where OAL is the total working length of the system. This constraint allows the system to have a smaller space requirement at the same optical power.

[0047] D1 / OAL>0.6, where D1 is the optical aperture of the first lens 11; this is beneficial for reducing the axial size of the system while increasing optical energy efficiency.

[0048] Preferably, the back focus of the five-element optical lens is greater than 2 mm, maintaining a minimum gap to prevent interference between the lens and the light source imaging surface.

[0049] Preferably, the optical surfaces of the first lens 11 , the second lens 12 , the third lens 13 , the fourth lens 14 and the fifth lens 15 are all set to be aspherical surfaces.

[0050] Preferably, the fourth lens 14 and the fifth lens 15 are configured as a composite lens. The composite lens is easier to assemble and helps reduce interface energy loss.

[0051] Example 1: In this embodiment, the fourth lens 14 and the fifth lens 15 are configured as separate lenses; the structure of this embodiment is as follows: Figure 1 As shown, the MTF curve is as follows Figure 2 As shown, the magnification chromatic aberration curve Figure 3 As shown in the accompanying drawings, it can be seen that the magnification chromatic aberration of the system is very small. The following are the surface parameters of this embodiment.

[0052] Table 1

[0053]

[0054]

[0055] Table 2

[0056]

[0057] The expression for aspheric surface is as follows:

[0058]

[0059] Where z is the sag at position r of the aspheric surface; c is the paraxial curvature of the aspheric surface, c = 1 / R, (i.e., the paraxial curvature c is the inverse of the surface curvature radius R); k is the cone coefficient; A, B,.., J are high-order coefficients.

[0060] Table 3 (Other system parameters of this embodiment are)

[0061]

[0062] Table 4, Constraints of Example 1

[0063] Constraints Design Results |R1|>|R2| From the design table, know satisfaction |R4|<|R3| From the design table, know satisfaction f45>f1 From the parameter table, we know that f45>f3 From the parameter table, we know that f45>|f2| From the parameter table, we know that <h2 style=";text-align:left;direction:ltr">|R9| / |R10|<1.2<h2 style=";text-align:left;direction:ltr"> |R9| / |R10|=0.36, knowing satisfaction |f12| / f>6 |f12| / f=12.90, contentment OAL / f<2.6 OAL / f=1.89, satisfied D1 / OAL>0.6 D1 / OAL=0.71, contentment

[0064] In the second embodiment, the fourth lens 14 and the fifth lens 15 are configured as a composite integral structure. The structure of this embodiment is as follows: Figure 4 As shown, the MTF curve is as follows Figure 5 As shown, the magnification chromatic aberration curve Figure 6 As shown in the accompanying drawings, it can be seen that the magnification chromatic aberration of the system is very small. The following are the surface parameters of this embodiment.

[0065] Table 5

[0066]

[0067] The expression for aspheric surface is as follows:

[0068]

[0069] Where z is the sag at position r of the aspheric surface; c is the paraxial curvature of the aspheric surface, c = 1 / R, (i.e., the paraxial curvature c is the inverse of the surface curvature radius R); k is the cone coefficient; A, B,.., J are high-order coefficients.

[0070] Table 6

[0071]

[0072] Table 7

[0073]

[0074] Table 8, Constraints of Example 2

[0075]

[0076]

[0077] In summary, the above two embodiments can be concluded that, compared with ordinary lenses, the energy utilization rate of pixel headlights can be significantly improved, chromatic aberration can be reduced, and image quality resolution can be improved.

[0078] The above-described embodiments merely represent two implementation methods of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A five-element optical lens with high brightness and low chromatic aberration, characterized in that: The lens is composed of a first lens (11), an aperture (10), a second lens (12), a third lens (13), a fourth lens (14), and a fifth lens (15) in sequence from the object side to the image side along the optical axis; the fourth lens (14) and the fifth lens (15) form a lens group; The first lens (11) has positive optical power and both the object side surface and the image side surface are convex; The second lens (12) has a negative optical power and a concave image side surface; The third lens (13) has positive optical power and both the object side surface and the image side surface are convex; The fourth lens (14) is configured as a meniscus lens having negative optical power and curved toward the image side; The fifth lens (15) has positive optical power and a convex object side surface; And it satisfies the following conditions: |R4|<|R3|, wherein R3 is the radius of curvature of the object side surface of the second lens (12), and R4 is the radius of curvature of the image side surface of the second lens (12); f45>f1, f45>|f2|, f45>f3, wherein f3 is the equivalent focal length of the third lens (13), f1 is the equivalent focal length of the first lens (11), f2 is the equivalent focal length of the second lens (12), and f45 is the equivalent focal length of the combined lens group of the fourth lens (14) and the fifth lens (15); |R9| / |R10|<1.2, wherein R9 is the radius of curvature of the object side surface of the fifth lens (15), and R10 is the radius of curvature of the image side surface of the fifth lens (15); |f12| / f>6, f12 is the equivalent focal length of the combined lens group of the first lens (11) and the second lens (12), and f is the equivalent focal length of the system; OAL / f<2.6, where OAL is the total operating length of the system; D1 / OAL>0.6, D1 is the optical aperture of the first lens (11).

2. The five-element optical lens with high brightness and low chromatic aberration according to claim 1, characterized in that: At least a portion of the object side surface of the second lens (12) is curved toward the image side surface.

3. The five-element optical lens with high brightness and low chromatic aberration according to claim 1, characterized in that: The back focus distance of the five-element optical lens is greater than 2mm.

4. The five-element optical lens with high brightness and low chromatic aberration according to claim 1, characterized in that: The optical surfaces of the first lens (11), the second lens (12), the third lens (13), the fourth lens (14) and the fifth lens (15) are all configured as aspherical surfaces.

5. The five-element optical lens with high brightness and low chromatic aberration according to claim 1, characterized in that: The fourth lens (14) and the fifth lens (15) are configured as a composite lens.

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