Athermalization micro array LED projection lens

Abstract

The invention discloses an athermalization micro array LED projection lens. The athermalization micro array LED projection lens comprises a first lens, a diaphragm, a second lens, a third lens, a fourth lens and a fifth aspherical lens which are sequentially arranged from an object space to an image space along a main optical axis; the first lens is a biconvex or plano-convex lens with positive focal power; the second lens is a meniscus lens with positive focal power; the third lens is a biconcave or plano-concave lens with negative focal power; the fourth lens is a meniscus or plano-convex lens with positive focal power; and the fifth aspherical lens is a meniscus aspherical lens with positive focal power. The problem of serious outdoor athermalization phenomenon is effectively solved, through matching of important parameters such as surface curvature, interval and material characteristics among the lenses, the light path can be effectively controlled, the size of the lens can be greatly shortened, the cost of the lens can be reduced, and meanwhile, various aberrations can be effectively controlled; the imaging quality is improved; and the lens has better thermal stability.

Description

Technical Field

[0001] The present invention relates to the technical field of optical projection and optical lighting, and in particular to an athermal micro-array LED projection lens. Background Art

[0002] With the development of semiconductor technology and the diversification of the projection field, people's demand for projection equipment has become more extensive and diverse. Micro projectors have been widely used in personal entertainment, business office, education and training due to their small size and portability.

[0003] Most of the micro LED projection lenses on the market currently use traditional cooling and thermal management designs. However, as the brightness of the light source increases, the heat generated by the LED array also increases, which has a significant impact on the optical performance and service life of the projection system. Especially when the temperature difference in the outdoor environment is relatively large, the lens is prone to high and low temperature thermal defocusing. The high and low temperature difference causes the resolution to deteriorate, making the use process more complicated; and the low lumen lens optical system does not have an advantage in brighter outdoor environments, and cannot be compatible with simple outdoor projection and lighting at the same time.

[0004] In order to solve the above problems, an embodiment of the present invention aims to provide an athermalized micro-array LED projection lens, aiming to solve the problem of thermalization of the micro-LED projection lens. Summary of the invention

[0005] The object of the present invention is to provide an athermalized micro-array LED projection lens to solve the problem of serious outdoor athermalization.

[0006] To achieve this object, the present invention adopts the following technical solutions: A heatless micro-array LED projection lens, the heatless micro-array LED projection lens comprises a first lens, an aperture, a second lens, a third lens, a fourth lens and a fifth aspheric lens arranged in sequence from the object side to the image side along the main optical axis; the first lens is a biconvex or plano-convex lens with positive focal power; the second lens is a meniscus lens with positive focal power; the third lens is a biconcave or plano-concave lens with negative focal power; the fourth lens is a meniscus or plano-convex lens with positive focal power; the fifth aspheric lens is a meniscus aspheric lens with positive focal power.

[0007] Furthermore, the focal length of the first lens of the athermalized micro-array LED projection lens is The following conditions are met: .

[0008] Furthermore, the focal length of the second lens of the athermalized micro-array LED projection lens is The following conditions are met: .

[0009] Furthermore, the focal length of the third lens of the athermalized micro-array LED projection lens is The following conditions are met: .

[0010] Furthermore, the focal length of the fourth lens of the athermalized micro-array LED projection lens is The following conditions are met: .

[0011] Furthermore, the focal length of the fifth aspherical lens of the athermalized micro-array LED projection lens is The following conditions are met: .

[0012] Furthermore, the focal length of the athermalized micro-array LED projection lens is , the total length of the lens L, satisfies the following relationship: .

[0013] Furthermore, the refractive index of at least one of the first lens and the second lens is between 1.60 and 1.80; The refractive index of the third lens is between 1.64 and 1.95.

[0014] Furthermore, at least one of the first lens and the second lens has an Abbe number between 50 and 60; and the Abbe number of the third lens is between 19 and 34.

[0015] Furthermore, the aperture F of the athermalized micro-array LED projection lens satisfies the following relationship: .

[0016] Compared with the prior art, the present invention has the following beneficial effects: By matching important parameters such as surface curvature, spacing, material properties, etc. between lenses, the light path can be effectively controlled, the lens size can be greatly shortened, the lens cost can be reduced, and the geometric efficiency of the lens can be effectively improved. Various aberrations can be effectively controlled, the imaging quality and high light efficiency can be improved, and the lens has better thermal stability, which can effectively improve the serious phenomenon of outdoor athermalization and the problem of switching between compatible outdoor projection systems and lighting systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0018] The structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with this technology. They are not used to limit the conditions under which the present invention can be implemented, and therefore have no substantive technical significance. Any structural modification, change in proportion or adjustment of size, without affecting the effects and purposes that can be achieved by the present invention, should still fall within the scope of the technical contents disclosed by the present invention.

[0019] Figure 1 It is a structural schematic diagram of an embodiment of an athermal micro-array LED projection lens of the present invention; Figure 2 A graph showing field curvature and distortion curves of an embodiment of an athermalized micro-array LED projection lens of the present invention; Figure 3 Schematic diagram of MTF 20lp / mm of an embodiment of an athermal micro-array LED projection lens of the present invention; Figure 4 A schematic diagram of MTF 12.5 mp / mm at ambient temperature of 27° C. for an embodiment of an athermalized micro-array LED projection lens of the present invention; Figure 5 A schematic diagram of MTF 12.5 mp / mm at an ambient temperature of 90° C. for an embodiment of an athermalized micro-array LED projection lens of the present invention; Figure 6 A schematic diagram of MTF 12.5 mp / mm at an ambient temperature of -20°C for an embodiment of an athermalized micro-array LED projection lens of the present invention; Figure 7 It is a structural schematic diagram of an embodiment of an athermal micro-array LED projection lens of the present invention; Figure 8 A graph showing field curvature and distortion curves of an embodiment of an athermalized micro-array LED projection lens of the present invention; Fig. 9 Schematic diagram of MTF 20lp / mm of an embodiment of an athermal micro-array LED projection lens of the present invention; Fig.10A schematic diagram of MTF 12.5 mp / mm at ambient temperature of 27° C. for an embodiment of an athermalized micro-array LED projection lens of the present invention; Fig.11 A schematic diagram of MTF 12.5 mp / mm at an ambient temperature of 90° C. for an embodiment of an athermalized micro-array LED projection lens of the present invention; Fig.12 A schematic diagram of MTF 12.5 mp / mm at an ambient temperature of -20°C for an embodiment of an athermalized micro-array LED projection lens of the present invention; Fig.13 A schematic diagram of light effects simulated by an embodiment of an athermal micro-array LED projection lens of the present invention.

[0020] Illustration description: G1, first lens; G2, second lens; G3, third lens; G4, fourth lens; G5, fifth aspherical lens. DETAILED DESCRIPTION

[0021] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] In the description of the present invention, it should be understood that the terms "upper", "lower", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. It should be noted that when a component is considered to be "connected" to another component, it may be directly connected to the other component or there may be a centrally arranged component at the same time.

[0023] like Figure 1As shown, the athermal micro-array LED projection lens system of the present application includes, from left to right: a first lens G1, an aperture ST0, a second lens G2, a third lens G3, a fourth lens G4 and a fifth aspherical lens G5; wherein S1 is the screen end of the first lens G1, S2 is the image source end of the first lens G1, ST0 represents the aperture, S4 is the screen end of the second lens G2, S5 is the image source end of the second lens G2, S6 is the screen end of the third lens G3, S7 is the image source end of the third lens G3, S8 is the screen end of the fourth lens G4, S9 is the image source end of the fourth lens G4, S10 is the screen end of the fifth aspherical lens G5, S11 is the image source end of the fifth aspherical lens G5, and the solid line on the right side of S11 is the image source end (image plane).

[0024] The present invention discloses an athermal micro-array LED projection lens, which has five lenses in total. The athermal micro-array LED projection lens comprises a first lens G1, a second lens G2, a third lens G3, a fourth lens G4 and a fifth aspheric lens G5, which are sequentially arranged along a principal optical axis from the object side to the image side; the first lens G1 is a biconvex or plano-convex lens with positive focal power; the second lens G2 is a meniscus lens with positive focal power; the third lens G3 is a biconcave or plano-concave lens with negative focal power; the fourth lens G4 is a meniscus or plano-convex lens with positive focal power; and the fifth aspheric lens G5 is a meniscus aspheric lens with positive focal power.

[0025] Wherein, the focal length of the first lens G1 of the athermalized micro-array LED projection lens is The following conditions are met: .

[0026] The function of lenses with focal lengths between 65-79 mm is: the positive focal length provides a moderate viewing angle, which is neither too compressed nor has obvious perspective distortion, and can focus the light from the aperture.

[0027] It should be added that the units in the above conditions (unmarked) are by default millimeters, and all units not marked in this article are by default millimeters.

[0028] The focal length of the second lens G2 of the athermalized micro-array LED projection lens is The following conditions are met: .

[0029] Among them, the lens with a focal length between 52-62 mm has the following main features: natural viewing angle and avoiding distortion; providing moderate depth of field; the second lens G2 is a meniscus lens, which acts to correct spherical aberration to obtain a smaller spot size and higher performance to reduce optical distortion and chromatic aberration.

[0030] The focal length of the third lens G3 of the athermalized micro-array LED projection lens is The following conditions are met: .

[0031] The focal length here is a negative number because when the third lens G3 is a double concave lens, the propagation path of the light is changed to have a larger angle, mainly to expand the light, so that the lens has a larger aperture and ensure sufficient light efficiency.

[0032] The focal length of the fourth lens G4 of the athermalized micro-array LED projection lens is The following conditions are met: .

[0033] Among them, the lenses with focal lengths ranging from 44mm to 90mm mainly provide a flexible field of view. When the fourth lens G4 is a positive meniscus lens, it acts to correct spherical aberration and has a focusing effect on light, so that the light will not be greatly lost in the system.

[0034] The focal length of the fifth aspherical lens G5 of the athermalized micro-array LED projection lens is The following conditions are met: .

[0035] Among them, the lens with a focal length in the range of 40mm to 75mm, the fifth aspherical lens G5 is a meniscus lens, which acts to correct spherical aberration in order to obtain a smaller diffuse spot, reduce the optical distortion and chromatic aberration of the system to obtain higher performance and a larger light collection angle, so that the light at the chip end can be well collected in the system, so that the optical system can obtain a larger aperture and a higher light efficiency.

[0036] The focal length of the athermalized micro-array LED projection lens , the total length of the lens L, satisfies the following relationship: .

[0037] Among them, when the athermal micro-array LED projection lens system satisfies the above relationship, the optical performance can be optimized, the imaging clarity can be improved, and the distortion can be reduced; the system compactness can be maintained, making the micro-LED projection equipment lighter and more portable; the thermal effect can be controlled, the influence of thermal expansion on the projected image can be reduced, and stability can be ensured; the throw ratio and focal length matching can be improved to ensure an ideal projection effect; and the optical design can be simplified to reduce the complexity of lens assembly.

[0038] The refractive index of at least one of the first lens G1 and the second lens G2 is between 1.60 and 1.80; the refractive index of the third lens G3 is between 1.64 and 1.95.

[0039] The Abbe number of at least one of the first lens G1 and the second lens G2 is between 50 and 60; the Abbe number of the third lens G3 is between 19 and 34.

[0040] The aperture F of the athermalized micro-array LED projection lens satisfies the following relationship: .

[0041] These design parameters not only improve the optical performance of the athermal micro-array LED projection lens, but also enhance the brightness, clarity and color performance of the projection system through the reasonable selection of refractive index, Abbe number and aperture value. By optimizing the refractive index and Abbe number, chromatic aberration and aberration are reduced, and the quality of the projected image is improved. The design of the aperture plays a key role in ensuring the balance of brightness and contrast, thereby achieving high-quality projection effects with high brightness, high clarity, low chromatic aberration and low distortion. These designs make the athermal micro-array LED projection lens system more adaptable to the high requirements of modern projection equipment for optical performance, compactness and thermal management.

[0042] Through the above arrangement, the first lens G1 is a double convex lens for converging light; the second lens G2 is a meniscus lens for correcting spherical aberration to obtain a smaller spot size and higher performance, and reduce optical distortion and chromatic aberration; the third lens G3 is a double concave lens for expanding light; the fourth lens G4 is a meniscus lens for correcting spherical aberration; the fifth aspheric lens G5 is a meniscus aspheric lens for correcting spherical aberration to obtain a smaller spot size, and reduce system optical distortion and chromatic aberration to obtain higher performance and a larger light collection angle, so that the optical system obtains higher light efficiency.

[0043] The athermal micro-array LED projection lens achieves the following functions through precise design of five lenses, combined with reasonable focal length configuration and lens combination: By optimizing the focal length and lens type, aberration, chromatic aberration and distortion are reduced, and the image quality is improved; Reasonable design reduces the negative impact of thermal effects on imaging and improves the stability and durability of the equipment; It meets the strict requirements of the micro LED projection system on volume and weight, and can realize small and lightweight projection equipment; Suitable for high-performance, high-definition projection needs, while ensuring the high efficiency and stability of the equipment; Through innovative optical design, the system optimizes the imaging effect and stability of the projection system, and adapts to the requirements of modern portable projection equipment for size, performance and thermal management.

[0044] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0045] Embodiment 1: like Figure 1 As shown, the present invention discloses an athermal micro-array LED projection lens, which has five lenses in total. The athermal micro-array LED projection lens includes a first lens G1, a second lens G2, a third lens G3, a fourth lens G4 and a fifth aspheric lens G5, which are sequentially arranged along the principal optical axis from the object side to the image side; the first lens G1 is a biconvex lens with positive focal power, with a convex surface S1 close to the object side and a convex surface S2 close to the image side; the second lens G2 is a concave-convex lens with positive focal power, with a convex surface S4 close to the object side and a concave surface S5 close to the image side; the third lens G3 is a biconcave lens with negative focal power, with a concave surface S6 close to the object side and a concave surface S7 close to the image side; the fourth lens G4 is a concave-convex lens with positive focal power, with a concave surface S8 close to the object side and a convex surface S9 close to the image side; the fifth aspheric lens G5 is a meniscus aspheric lens with positive focal power, with a convex surface S10 close to the object side and a concave surface S11 close to the image side.

[0046] It should be noted that the second lens G2 is a meniscus lens, which is also a concave-convex lens. The two are different names for the same thing, and for the convenience of explanation, concave and convex are used to distinguish them.

[0047] The detailed optical data of the athermalized micro-array LED projection lens of the first embodiment are shown in Tables 1-1 and 1-2 below. Table 1-1: Among them, R is the radius of curvature, D is the lens thickness or air space, nd material represents the refractive index, and vd material represents the Abbe number.

[0048] Table 1-2: The aspheric formula is as follows: ; Where Z is the sagittal height at the vertex of the aspheric surface when the aspheric surface is at a height r along the optical axis, k is the cone coefficient, and c is the curvature of the surface vertex. ...etc. are the coefficients of higher-order aspheric surfaces.

[0049] According to Table 1-1 and Table 1-2 above, the maximum field of view is 18.4° and the focal length is 39.9 mm.

[0050] Figures 1 to 6 The following are the structural diagram of the first embodiment, the field curvature and distortion curve diagram, the MTF 20lp / mm diagram, the MTF 12.5mp / mm diagram at ambient temperature 27°C, the MTF 12.5mp / mm diagram at ambient temperature high temperature 90°C, and the MTF 12.5mp / mm diagram at ambient temperature low temperature -20°C. It can be seen from the figure that the maximum field of view of the distortion correction in this system is less than 1.2%, the entire optical system has a high resolution, and its maximum MTF can reach 20lp / mm≥0.3, its normal temperature 27°C performance can reach about 12.5lp / mm≥0.57, its high temperature 90°C performance can reach about 12.5lp / mm≥0.5, and its low temperature -20°C performance can reach about 12.5lp / mm≥0.47.

[0051] From the MTF performance at the above temperatures, it can be seen that the lens has stable high and low temperature performance under environmental changes and its athermal performance is excellent.

[0052] Reference Fig.13 According to the lens simulation light effect, the maximum light efficiency of this embodiment can reach 39% at most and 36.5% at least.

[0053] Embodiment 2: like Figure 1 As shown, the present invention discloses an athermal micro-array LED projection lens, which has five lenses in total. The athermal micro-array LED projection lens includes a first lens G1, a second lens G2, a third lens G3, a fourth lens G4 and a fifth aspheric lens G5, which are sequentially arranged along the principal optical axis from the object side to the image side; the first lens G1 is a plano-convex lens with positive focal power, with a convex surface S1 close to the object side and a plane S2 close to the image side; the second lens G2 is a concave-convex lens with positive focal power, with a convex surface S4 close to the object side and a concave surface S5 close to the image side; the third lens G3 is a plano-concave lens with negative focal power, with a plane S6 close to the object side and a concave surface S7 close to the image side; the fourth lens G4 is a concave-convex lens with positive focal power, with a concave surface S8 close to the object side and a convex surface S9 close to the image side; the fifth aspheric lens G5 is a meniscus aspheric lens with positive focal power, with a convex surface S10 close to the object side and a concave surface S11 close to the image side.

[0054] It should be noted that in the second embodiment, since the image side of the first lens G1 is the S2 plane, in actual use, the stop ST0 and the S2 plane are attached to each other, so that the stop ST0 and the S2 plane overlap.

[0055] The detailed optical data of the athermalized micro-array LED projection lens of the second embodiment are shown in Tables 2-1 and 2-2 below. Table 2-1: In Table 2-1, R is the radius of curvature, D is the lens thickness or air space, nd material represents the refractive index, and vd material represents the Abbe number.

[0056] Table 2-2: The aspheric formula is as follows: ; Where Z is the sagittal height at the vertex of the aspheric surface when the aspheric surface is at a height r along the optical axis, k is the cone coefficient, and c is the curvature of the surface vertex. ...etc. are the coefficients of higher-order aspheric surfaces.

[0057] It can be seen from Table 2-1 and Table 2-2 above that its maximum field of view angle is 20° and the focal length is 39.9.

[0058] Figures 7 to 12 The following are the structural diagram of the first embodiment, the field curvature and distortion curve diagram, the MTF 20lp / mm diagram, the MTF 12.5mp / mm diagram at ambient temperature 27°C, the MTF 12.5mp / mm diagram at ambient temperature high temperature 90°C, and the MTF 12.5mp / mm diagram at ambient temperature low temperature -20°C. It can be seen from the figure that the maximum field of view of the distortion correction in this system is less than 1.2%; the entire optical system has a high resolution, and its maximum MTF can reach 20lp / mm≥0.3; its normal temperature 27°C performance can reach about 12.5lp / mm≥0.53; its high temperature 90°C performance can reach about 12.5lp / mm≥0.5; its low temperature -20°C performance can reach about 12.5lp / mm≥0.0.5.

[0059] From the MTF performance at the above temperatures, it can be seen that the lens has stable high and low temperature performance under environmental changes and its athermal performance is excellent.

[0060] Reference Fig.13 According to the lens simulation light effect, the maximum light efficiency of this embodiment can reach 39% at most and 36.5% at least.

[0061] Through the above embodiments, the lens layout of the optical system of the optical lens is arranged along the main optical axis from the object side to the image side in the corresponding order of the lenses, which are the first lens G1, the aperture ST0, the second lens G2, the third lens G3, the fourth lens G4 and the fifth aspherical lens G5, which is at least an aspherical lens. Through the matching of important parameters such as the surface curvature, spacing, and material properties between the lenses, the light path can be effectively controlled, the lens size can be greatly shortened, the lens cost can be reduced, and the geometric efficiency of the lens can be effectively improved. It can also effectively control various aberrations, improve imaging quality, improve high light efficiency, and the lens has better thermal stability. In the optical system embodiment of the present invention, the lens size can be better shortened and the cost can be reduced while the projection quality can be improved. The lens has athermal imaging performance in high temperature environments inside and outside, and has a larger aperture to ensure the excellent light efficiency of the lens.

[0062] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An athermalized micro-array LED projection lens, characterized in that: The athermalized micro-array LED projection lens comprises a first lens, an aperture, a second lens, a third lens, a fourth lens and a fifth aspherical lens arranged in sequence from the object side to the image side along the main optical axis; The first lens is a biconvex or plano-convex lens with positive optical power; The second lens is a meniscus lens with positive optical power; The third lens is a biconcave or plano-concave lens with negative optical power; The fourth lens is a meniscus or plano-convex lens with positive power; The fifth aspheric lens is a meniscus aspheric lens with positive refractive power.

2. The athermalized micro-array LED projection lens according to claim 1, characterized in that: The focal length of the first lens of the athermalized micro-array LED projection lens is The following conditions are met: 。 3. The athermalized micro-array LED projection lens according to claim 2, characterized in that: The focal length of the second lens of the athermalized micro-array LED projection lens is The following conditions are met: 。 4. The athermalized micro-array LED projection lens according to claim 3, characterized in that: The focal length of the third lens of the athermalized micro-array LED projection lens is The following conditions are met: 。 5. The athermalized micro-array LED projection lens according to claim 4, characterized in that: The focal length of the fourth lens of the athermalized micro-array LED projection lens is The following conditions are met: 。 6. The athermalized micro-array LED projection lens according to claim 5, characterized in that: The focal length of the fifth aspherical lens of the athermalized micro-array LED projection lens is The following conditions are met: 。 7. The projection lens according to any one of claims 1 to 6, characterized in that: The focal length of the athermalized micro-array LED projection lens , the total length of the lens L, satisfies the following relationship: 。 8. The athermalized micro-array LED projection lens according to claim 1, wherein: The refractive index of at least one of the first lens and the second lens is between 1.60 and 1.80; The refractive index of the third lens is between 1.64 and 1.

95.

9. The athermalized micro-array LED projection lens according to claim 1, wherein: The Abbe number of at least one of the first lens and the second lens is between 50 and 60; The Abbe number of the third lens is between 19 and 34.

10. The athermalized micro-array LED projection lens according to claim 1, characterized in that: The aperture F of the athermalized micro-array LED projection lens satisfies the following relationship: 。

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