Lens and single-chip LCD projector

Abstract

The utility model discloses a lens and a single-chip LCD projector, the single-chip LCD projector comprises the lens, and the lens comprises a first lens, a second lens and a third lens which are coaxially arranged in sequence along the emergent light direction of the lens; the first lens and the third lens have positive focal power, and the second lens has negative focal power. Wherein the refractive index Nd1 of the first lens meets the condition that Nd1 is larger than or equal to 1.65 and smaller than or equal to 1.7, the refractive index Nd2 of the second lens meets the condition that Nd2 is larger than or equal to 1.65 and smaller than or equal to 1.7, and the refractive index Nd3 of the third lens meets the condition that Nd3 is larger than or equal to 1.60 and smaller than or equal to 1.67. And meanwhile, a 1080P high-definition imaging rate can also be realized.

Description

Technical Field

[0001] The present application relates to the technical field of lenses, and in particular to a lens and a single-chip LCD projector. Background Art

[0002] In order to ensure that the price of single-chip LCD projectors remains within a reasonable range, three-piece fixed-focus lenses are usually used, and low-cost optical glass materials such as H-ZK11 and H-ZF2 are selected. These lenses have the advantages of simple processing and low cost, but they also have the disadvantages of low resolution and poor projection effect.

[0003] At the same time, the market demand for projection equipment that can project large images at a short distance is also growing. Therefore, it is very important to develop a lens that can project a large image with high resolution. Utility Model Content

[0004] The embodiment of the present application provides a lens and a single-chip LCD projector. The present application has a simple structure and can project a large and clear image at a short distance, meeting the requirements of miniaturization and large screen of the single-chip LCD projector, while also achieving a 1080P high-definition imaging rate.

[0005] In a first aspect, an embodiment of the present application provides a lens for a single-chip LCD projector, the lens comprising: a first lens, a second lens, and a third lens coaxially arranged in sequence along an outgoing light direction of the lens;

[0006] The first lens and the third lens both have positive refractive power, and the second lens has negative refractive power;

[0007] The refractive index Nd1 of the first lens satisfies: 1.65≤Nd1≤1.7, the refractive index Nd2 of the second lens satisfies: 1.65≤Nd2≤1.7, and the refractive index Nd3 of the third lens satisfies: 1.60≤Nd3≤1.67.

[0008] In a possible implementation, the Abbe number Vd1 of the first lens satisfies: 50≤Vd1≤60;

[0009] The Abbe number Vd2 of the second lens satisfies: 25≤Vd2≤35;

[0010] The Abbe number Vd3 of the third lens satisfies: 45≤Vd3≤55.

[0011] Based on the lens of the embodiment of the present application, the single-chip LCD projection lens reasonably arranges the positive and negative focal lengths, refractive indices and Abbe numbers, thicknesses and center intervals of the three lenses, so that the light passes through the positive and negative lenses in turn and converges and diverges to varying degrees. It can effectively correct various aberrations of the optical system and achieve a projection ratio of 1.25, meeting the requirements of miniaturization and large screen of single-chip LCD projectors, while also achieving a 1080P high-definition imaging rate.

[0012] In this implementation, the Abbe number range values ​​of the first lens, the second lens, and the third lens provided in this application can reduce the dispersion effect, improve the image quality, and optimize the spherical aberration performance of the lens to improve the clarity and accuracy of the image.

[0013] In a possible implementation, the center distance between the first lens and the second lens is 6-7 mm.

[0014] In this implementation, the center distance between the first lens and the second lens is limited to improve the clarity of the lens.

[0015] In a possible implementation, the center distance between the second lens and the third lens is 7.9-9 mm.

[0016] In this implementation, the center distance between the second lens and the third lens is limited to improve the clarity of the lens.

[0017] In a possible implementation, the center thickness T1 of the first lens satisfies: 8.0 mm ≤ T1 ≤ 12.0 mm;

[0018] The center thickness T2 of the second lens satisfies: 2.0mm≤T2≤6.0mm;

[0019] The central thickness T3 of the third lens satisfies: 6.0 mm≤T3≤10.0 mm.

[0020] In this implementation, the center thicknesses of the first lens, the second lens, and the third lens are selected so as to meet not only the production cost requirement but also the clarity requirement of the lens.

[0021] In a possible implementation, a curvature radius R31 of an end surface of the first lens on a side close to the second lens satisfies: 100 mm ≤ R31 ≤ 200 mm, and a curvature radius R32 of an end surface of the first lens on a side away from the second lens satisfies: -60 mm ≤ R32 ≤ -30 mm;

[0022] The curvature radius R41 of the end surface of the second lens close to the third lens satisfies: -100mm≤R42≤-50mm, and the curvature radius R42 of the end surface of the second lens close to the first lens satisfies: 40mm≤R41≤100mm;

[0023] A curvature radius R51 of an end surface of the third lens away from the second lens satisfies: 30mm≤R51≤60mm, and a curvature radius R52 of an end surface of the third lens close to the second lens satisfies: 500mm≤R52≤1000mm.

[0024] In a possible implementation, the refractive index of the first lens is 1.69, the refractive index of the second lens is 1.67, and the refractive index of the third lens is 1.65.

[0025] In a possible implementation, a Fresnel lens is further included, and the Fresnel lens, the first lens, the second lens and the third lens are arranged in sequence along the direction of the outgoing light of the lens;

[0026] The center distance between the Fresnel lens and the first lens is 78-79 mm, and the center thickness T5 of the Fresnel lens is 1.8-2.2 mm.

[0027] Based on the above embodiments, the single-chip LCD projection lens can effectively correct various aberrations of the optical system by reasonably arranging the positive and negative focal lengths, refractive indices and Abbe numbers, thicknesses and center intervals of the three lenses and the Fresnel lens, so that the light rays converge and diverge to different degrees through the positive and negative lenses in sequence, so that the resolution of the lens can match the 1080P resolution of the 3.5-inch LCD liquid crystal light valve, and can achieve a projection ratio of 1.25, which can meet the requirements of miniaturization and large screen of the single-chip LCD projector.

[0028] In a second aspect, an embodiment of the present application further provides a single-chip LCD projector, comprising an LCD display screen and the above-mentioned lens, wherein the LCD display screen, the Fresnel lens, the first lens, the second lens and the third lens are sequentially arranged along the direction of the outgoing light of the single-chip LCD projector;

[0029] Among them, the center distance between the Fresnel lens and the LCD display screen is 9.5mm.

[0030] In a possible implementation, a reflector is further included, and the reflector is arranged at a 45° tilt to reflect the light emitted from the LCD display screen by 90° and then make it incident on the above-mentioned lens. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present application 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 application. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0032] Figure 1 A schematic diagram of a single-chip LCD projector according to an embodiment of the present application;

[0033] Figure 2 A modulation transfer function curve corresponding to a lens of an embodiment provided in an embodiment of the present application;

[0034] Figure 3 A distortion curve corresponding to a lens of an embodiment provided in an embodiment of the present application;

[0035] Figure 4 A schematic diagram of a single-chip LCD projector according to another embodiment of the present application.

[0036] Description of Figure Numbers:

[0037] 10. LCD display screen; 20. Fresnel lens; 30. First lens; 40. Second lens; 50. Third lens; 60. Reflector.

[0038] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0039] In order to make the objectives, technical solutions and advantages of the present application clearer, the following part will further describe the embodiments of the present application in detail in conjunction with the accompanying drawings.

[0040] When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. Instead, they are only examples of devices and methods consistent with some aspects of the present application as detailed in the attached claims.

[0041] In the description of the present application, it should be understood that the terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances. In addition, in the description of the present application, unless otherwise specified, "multiple" refers to two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the objects associated before and after are in an "or" relationship.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used in this specification are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0043] In order to ensure that the price of single-chip LCD projectors remains within a reasonable range, three-piece fixed-focus lenses are usually used, and low-cost optical glass materials such as H-ZK11 and H-ZF2 are selected. These lenses have the advantages of simple processing and low cost, but they also have the disadvantages of low resolution and poor projection effect.

[0044] At the same time, the market demand for projection equipment that can project large images at a short distance is also growing. Therefore, it is very important to develop a lens that can project a large image with high resolution.

[0045] In order to solve the problem of imaging clarity of the lens, the present application embodiment proposes a lens for a single-chip LCD projector. Figure 1 The lens includes a first lens 30, a second lens 40 and a third lens 50 which are coaxially arranged in sequence along the direction of the output light of the lens.

[0046] The first lens 30 and the third lens 50 both have positive optical power, and the second lens 40 has negative optical power. Optical power is used to indicate the ability to deflect light. When a lens has positive optical power, it makes parallel light passing through the lens converge to form a real image behind the lens. When a lens has negative optical power, it makes parallel light passing through the lens diverge behind the lens.

[0047] The refractive index Nd1 of the first lens 30 satisfies: 1.65≤Nd1≤1.7, the refractive index Nd2 of the second lens 40 satisfies: 1.65≤Nd2≤1.7, and the refractive index Nd3 of the third lens 50 satisfies: 1.60≤Nd3≤1.67.

[0048] In some embodiments of the present application, the refractive index of the first lens 30 is 1.69, the refractive index of the second lens 40 is 1.67, and the refractive index of the third lens 50 is 1.65.

[0049] Based on the lens of the embodiment of the present application, the present application arranges the first lens 30, the second lens 40 and the third lens 50 at intervals along the direction of the light emission of the lens, and the axes of the first lens 30, the second lens 40 and the third lens 50 are coaxial, and the light emitted by the light source of the single-chip LCD projector is sequentially emitted through the first lens 30, the second lens 40 and the third lens 50. The present application selects the positive and negative focal lengths and refractive indices of the first lens 30, the second lens 40 and the third lens 50, so that the light can reach a projection ratio of 1.25 after different degrees of convergence and divergence through the positive and negative lenses in sequence, which can meet the requirements of miniaturization and large screen of the single-chip LCD projector, and can also achieve 1080P high-definition imaging rate.

[0050] In some embodiments of the present application, the Abbe number Vd1 of the first lens 30 satisfies: 50≤Vd1≤60; the Abbe number Vd2 of the second lens 40 satisfies: 25≤Vd2≤35; and the Abbe number Vd3 of the third lens 50 satisfies: 45≤Vd3≤55.

[0051] It should be noted that the Abbe number is related to the dispersion ability of the lens. The Abbe number range values ​​of the first lens 30, the second lens 40 and the third lens 50 provided in the present application can help control the chromatic aberration of the lens. Chromatic aberration refers to the color shift or blurring of the image edge caused by the light of different wavelengths converging at different positions after passing through the lens. The embodiments of the present application can reduce the dispersion effect and improve the image quality. In addition, the selection of the Abbe number can also help reduce spherical aberration, that is, the change in the focal position of the lens under different incident angles. Spherical aberration can cause blurring and distortion of the image. The Abbe number range values ​​of the first lens 30, the second lens 40 and the third lens 50 provided in the present application can optimize the spherical aberration performance of the lens and improve the clarity and accuracy of the image.

[0052] The center distance between the first lens 30 and the second lens 40 may be 6-7 mm. In some embodiments, the center distance between the first lens 30 and the second lens 40 is 6.5 mm. The center distance between the second lens 40 and the third lens 50 is 7.9-9 mm. In some embodiments, the center distance between the second lens 40 and the third lens 50 may be 8.4 mm. By limiting the center distance between the first lens 30 and the second lens 40 and the center distance between the second lens 40 and the third lens 50, the clarity of the lens is improved.

[0053] It should be noted that the center distance between the first lens 30 and the second lens 40 refers to the distance between the axis of the first lens 30 and the axis of the second lens 40 along the direction of the optical path, and the center distance between the second lens 40 and the third lens 50 refers to the distance between the axis of the second lens 40 and the axis of the third lens 50 along the direction of the optical path. In the field of lens technology, those skilled in the art can determine the axis position of the lens, and thus can clearly choose to set the distance between the two lenses.

[0054] The center thickness T1 of the first lens 30 satisfies: 8.0mm≤T1≤12.0mm; the center thickness T2 of the second lens 40 satisfies: 2.0mm≤T2≤6.0mm; the center thickness T3 of the third lens 50 satisfies: 6.0mm≤T3≤10.0mm. By selecting the center thicknesses of the first lens 30, the second lens 40 and the third lens 50, not only the production cost requirement but also the definition requirement of the lens can be met.

[0055] The curvature radius R32 of the end surface of the first lens 30 on the side away from the second lens 40 satisfies: -60mm≤R32≤-30mm, and the curvature radius R31 of the end surface of the first lens 30 on the side close to the second lens 40 satisfies: 100mm≤R31≤200mm; the curvature radius R42 of the end surface of the second lens 40 on the side close to the first lens 30 satisfies: 40mm≤R41≤100mm, and the curvature radius R41 of the end surface of the second lens 40 on the side close to the third lens 50 satisfies: -100mm≤R42≤-50mm; the curvature radius R51 of the end surface of the third lens 50 on the side away from the second lens 40 satisfies: 30mm≤R51≤60mm, and the curvature radius R52 of the end surface of the third lens 50 on the side close to the second lens 40 satisfies: 500mm≤R52≤1000mm.

[0056] Based on the lens of the present application, by reasonably arranging the positive and negative focal lengths, refractive index and Abbe number, thickness and center interval of the three lenses, the light will converge and diverge to varying degrees after passing through the positive and negative lenses in sequence, thereby improving the resolution of the projection lens, enabling it to match the 1080P resolution of the 3.5-inch LCD liquid crystal light valve, and can achieve a projection ratio of 1.25, meeting the needs of miniaturization and large screen of single-chip LCD projectors.

[0057] In some specific embodiments of the present application, the curvature radius R51 of the end surface of the third lens 50 away from the second lens 40 is 34.9 mm, the curvature radius R52 of the end surface of the third lens 50 close to the second lens 40 is 541.6 mm, the center thickness T1 of the third lens 50 is 7.5 mm, the refractive index is 1.67, and the Abbe number is 50.8. The curvature radius R41 of the end surface of the second lens 40 close to the third lens 50 is 68.1 mm, the curvature radius R42 of the end surface of the second lens 40 close to the first lens 30 is -45.3 mm, the center thickness T2 of the second lens 40 is 2.6 mm, the refractive index is 1.67, and the Abbe number is 32.2. The curvature radius R31 of the end surface of the first lens 30 close to the second lens 40 is 125.2 mm, and the curvature radius R32 of the end surface of the first lens 30 away from the second lens 40 is -35.7 mm. The first lens 30 has a central thickness T2 of 8 mm, a refractive index of 1.69, and an Abbe number of 55.5.

[0058] Please refer to Figures 2 to 3 , Figure 2 It is the modulation transfer function curve of the projection lens in the above specific embodiment. Modulation transfer function (MTF) is a performance index of an optical system, which represents the system's ability to transmit signals of different spatial frequencies. The resolution of a 3.5-inch LCD liquid crystal light valve is 1920*1080, the pixel size is 40.5 microns, and the corresponding spatial resolution is 12.3lp / mm. The full-field MTF of the projection lens at 12.3lp / mm is greater than 0.2. Figure 2 In the figure, the full-field MTF of the projection lens at 12.3lp / mm is greater than 0.2, indicating that the lens has a good transmission capability for the signal of this spatial frequency and can maintain high image details. Figure 3 is the distortion curve corresponding to the projection lens in the above specific embodiment. Distortion is a common error in optical systems, which can cause image deformation and distortion. Figure 3 In the 3D image processing, the optical distortion of the projection lens is less than 0.7%, and the corresponding TV distortion is less than 0.5%. This means that the distortion error of the projection lens is relatively small and can provide better image quality and accuracy.

[0059] In summary, the projection lens of the embodiment of the present application has a higher modulation transfer function at 12.3lp / mm, and can maintain higher image details; at the same time, its distortion error is also relatively small, and can provide better image quality and accuracy.

[0060] The first lens 30 can be made of a material with a glass grade of H-ZBAF50, the second lens 40 can be made of a material with a glass grade of H-ZF2, and the third lens 50 can be made of a material with a glass grade of H-LAK51A. In addition, the diameter of the first lens 30 is 44 mm, the diameter of the second lens 40 is 40 mm, and the diameter of the third lens 50 is 48 mm. In this way, the requirement of a small lens volume can be met and the occupied space can be reduced.

[0061] In some embodiments of the present application, the lens further includes a Fresnel lens 20, and the Fresnel lens 20, the first lens 30, the second lens 40, and the third lens 50 are arranged in sequence along the direction of the outgoing light of the lens. The center distance between the Fresnel lens 20 and the first lens 30 may be 78-79 mm, and in some specific embodiments, the center distance between the Fresnel lens 20 and the first lens 30 is 78.5 mm. By limiting the distance between the Fresnel lens 20 and the first lens 30, the clarity of the single-chip LCD projector meets the design standard.

[0062] The center thickness T5 of the Fresnel lens 20 can be 1.8-2.2 mm. In some specific embodiments, the center thickness T5 of the Fresnel lens 20 is 2.0 mm. By limiting the center thickness of the Fresnel lens 20, the center thicknesses of the Fresnel lens 20 and the three lenses cooperate with each other, and the imaging clarity of the single-chip LCD projector can be improved. Among them, the curvature radius of the surface of the Fresnel lens 20 close to the first lens 30 is infinite (that is, a plane), and the surface away from the first lens 30 is a Fresnel surface, and the annular sawtooth structure of the Fresnel surface is an equal width design or an equal depth design.

[0063] The above-mentioned Fresnel lens 20 may be made of, but not limited to, a plastic material such as PMMA, and has a plurality of concentric corrugated structures on its surface to form a collimating lens structure. The Fresnel lens 20 may be made of, but not limited to, a plastic material such as PMMA, and has a plurality of concentric corrugated structures on its surface to form a focusing lens structure. In some structural forms, the outer contour of the Fresnel lens 20 may be a rectangle with a size of 89 mm*52 mm.

[0064] Based on the lens of the embodiment of the present application, the single-chip LCD projection lens reasonably arranges the positive and negative focal lengths, refractive indices and Abbe numbers, thicknesses and center intervals of the three lenses and the Fresnel lens 20, so that the light rays converge and diverge to different degrees through the positive and negative lenses in sequence, and various aberrations of the optical system can be effectively corrected, so that the resolution of the projection lens can match the 1080P resolution of the 3.5-inch LCD liquid crystal light valve, and at the same time can achieve a projection ratio of 1.25, which can meet the requirements of miniaturization and large screen of the single-chip LCD projector.

[0065] Second, see Figure 1 and Figure 4 The embodiment of the present application provides a single-chip LCD projector, including an LCD display screen 10 and the above-mentioned lens, wherein the LCD display screen 10, the Fresnel lens 20, the first lens 30, the second lens 40 and the third lens 50 are sequentially arranged along the direction of the outgoing light of the single-chip LCD projector. When working, light sequentially passes through the LCD display screen 10, the Fresnel lens 20, the first lens 30, the second lens 40 and the third lens 50 to form an image.

[0066] It should be noted that the single-chip LCD projector here refers to the number of liquid crystal panels used inside the projector. The single-chip LCD projector of the present application uses a liquid crystal panel (i.e., LCD display screen 10) to process all color information, and synthesizes a color image by alternately adjusting the transmittance of the three basic colors of red, green, and blue. Compared with the form of using multiple liquid crystal panels inside the projector in the related art, such as the 3LCD projection technology uses three liquid crystal panels, the single-chip liquid crystal projector of the embodiment of the present application only needs one liquid crystal panel, so it will be more economical in manufacturing cost, relatively light and thin in size and weight, easy to carry and install, and more energy-saving in power consumption.

[0067] In some embodiments of the present application, the center distance between the Fresnel lens 20 and the LCD display screen 10 is 9.5 mm. By limiting the distance between the LCD display screen 10 and the Fresnel lens 20, the clarity of the single-chip LCD 1 projector meets the design standard.

[0068] In order to reduce the length of the projection lens, a reflector 60 is added between the Fresnel lens 20 and the first lens 30. Figure 4 The reflector 60 is tilted at 45° to reflect the light emitted from the LCD display screen 10 by 90° and then make it incident on the above-mentioned lens.

[0069] The substrate of the reflector 60 may be made of glass, and its reflection function may have the following solutions:

[0070] 1. Use reflective materials (such as reflective film or reflective stickers, etc.), cut these reflective materials into shapes that match the substrate, and attach them to the surface of the substrate with adhesive or glue; 2. Use reflective coatings (such as reflective paint or aluminum reflective coatings or titanium dioxide reflective coatings), use brushes, spray guns or other coating tools to evenly apply the reflective coatings on the surface of the substrate to form a reflective coating that can reflect light. It can be understood that multiple coatings can be performed to ensure the thickness and uniformity of the reflective coating, thereby ensuring the stability of the light reflected by the reflective coating. After the coating is completed, drying and curing treatments are performed to make the reflective layer firmly attached to the substrate; 3. Place the substrate in a vacuum coating device, and deposit reflective materials (such as aluminum, silver, silicon dioxide or material) on the surface of the substrate through coating techniques such as evaporation or magnetron sputtering or physical vapor deposition or chemical vapor deposition to form a reflective dielectric reflective film layer on the surface of the substrate. By controlling parameters such as coating temperature, vacuum degree and coating time, the thickness and quality of the dielectric reflective film layer can be ensured. Here, the present application does not impose any specific limitation on the formation method of the reflector 60 .

[0071] Based on the single-chip LCD projector of the embodiment of the present application, by adopting the above-mentioned lens, various aberrations of the optical system can be effectively corrected, so that the resolution of the projection lens can match the 1080P resolution of the 3.5-inch LCD liquid crystal light valve, and at the same time, a projection ratio of 1.25 can be achieved, which can meet the requirements of miniaturization and large screen of the single-chip LCD projector. By setting the reflector 60, the overall volume of the single-chip LCD projector can be reduced, and the occupied space can be reduced.

[0072] The same or similar numbers in the drawings of this embodiment correspond to the same or similar parts; in the description of this application, it should be understood that if the terms "up", "down", "left", "right", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the drawings, it is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limitations on this application. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0073] The above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A lens for a single-chip LCD projector, characterized in that: The lens comprises: a first lens, a second lens and a third lens which are coaxially arranged in sequence along the direction of the outgoing light of the lens; The first lens and the third lens both have positive refractive power, and the second lens has negative refractive power; The refractive index Nd1 of the first lens satisfies: 1.65≤Nd1≤1.7, the refractive index Nd2 of the second lens satisfies: 1.65≤Nd2≤1.7, and the refractive index Nd3 of the third lens satisfies: 1.60≤Nd3≤1.

67.

2. The lens according to claim 1, characterized in that: The Abbe number Vd1 of the first lens satisfies: 50≤Vd1≤60; The Abbe number Vd2 of the second lens satisfies: 25≤Vd2≤35; The Abbe number Vd3 of the third lens satisfies: 45≤Vd3≤55.

3. The lens according to claim 1, characterized in that: The center distance between the first lens and the second lens is 6-7 mm.

4. The lens according to claim 1, characterized in that: The center distance between the second lens and the third lens is 7.9-9 mm.

5. The lens according to claim 1, characterized in that: The center thickness T1 of the first lens satisfies: 8.0 mm ≤ T1 ≤ 12.0 mm; The center thickness T2 of the second lens satisfies: 2.0 mm ≤ T2 ≤ 6.0 mm; The central thickness T3 of the third lens satisfies: 6.0 mm≤T3≤10.0 mm.

6. The lens according to claim 1, characterized in that: The curvature radius R31 of the end surface of the first lens on the side close to the second lens satisfies: 100 mm ≤ R31 ≤ 200 mm, and the curvature radius R32 of the end surface of the first lens on the side away from the second lens satisfies: -60 mm ≤ R32 ≤ -30 mm; The curvature radius R41 of the end surface of the second lens close to the third lens satisfies: -100mm≤R42≤-50mm, and the curvature radius R42 of the end surface of the second lens close to the first lens satisfies: 40mm≤R41≤100mm; A curvature radius R51 of an end surface of the third lens away from the second lens satisfies: 30mm≤R51≤60mm, and a curvature radius R52 of an end surface of the third lens close to the second lens satisfies: 500mm≤R52≤1000mm.

7. The lens according to any one of claims 1 to 6, characterized in that: The refractive index of the first lens is 1.69, the refractive index of the second lens is 1.67, and the refractive index of the third lens is 1.

65.

8. The lens according to any one of claims 1 to 6, characterized in that: It also includes a Fresnel lens, wherein the Fresnel lens, the first lens, the second lens and the third lens are arranged in sequence along the direction of the outgoing light of the lens; Wherein, the center distance between the Fresnel lens and the first lens is 78-79 mm.

9. A single-chip LCD projector, characterized in that: The device comprises an LCD display screen and the lens according to any one of claims 1 to 8, wherein the lens comprises a Fresnel lens, a first lens, a second lens and a third lens; The LCD display screen, the Fresnel lens, the first lens, the second lens and the third lens are arranged in sequence along the direction of the outgoing light of the single-chip LCD projector; The center distance between the Fresnel lens and the LCD display screen is 9.5 mm, and the center thickness T5 of the Fresnel lens is 1.8-2.2 mm.

10. The single-chip LCD projector according to claim 9, characterized in that: It also includes a reflector, which is tilted at 45° to reflect the light emitted from the LCD display screen by 90° and then make it incident on the lens as described in any one of claims 1-8.

Images