2.69-inch LCD projection lens
By optimizing the lens combination and material selection of the 2.69-inch LCD projection lens, the issues of thermal defocusing and price have been resolved, achieving stable high-performance projection over a wide temperature range to meet the needs of a wide range of users.
Patent Information
- Application Number
- CN202511952757.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-23
- Publication Date
- 2026-02-03
AI Technical Summary
Existing projection lenses suffer from thermal defocusing due to heat buildup in high-brightness projectors, resulting in blurred images. Furthermore, high-performance lenses are expensive and cannot meet the needs of long-term projection, while inexpensive lenses have insufficient performance.
It adopts a 3-element optical structure of 1G2P (1 glass lens and 2 plastic aspherical lenses), including a first lens with positive optical power, a second lens with negative optical power, and a third lens with positive optical power. Combined with an aperture and Fresnel lens, the material selection and structural design are optimized to correct temperature drift and achieve stable operation.
It achieves stable operation in environments ranging from -20℃ to 60℃, with a resolution of 720P, a luminous flux of 150 lumens, a field of view of over 51°, an imaging plane of Φ34.2mm, a throw ratio of less than 1.26, a low price, and superior imaging performance, avoiding defocusing.
Smart Images
Figure CN121454744A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of projection lens, in particular to a 2.69-inch LCD projection lens. BACKGROUND
[0002] In recent years, due to the rapid development of visual information transmission mode such as video, picture, etc., the demand of consumers for information bearing and transmission equipment such as smart phones, computers, projection equipment and the like with good quality and low price is increasing. In the projection field, the projection lens is an extremely important part of the projection equipment, which is equivalent to our eyes. However, in the existing lens products on the market, the superior performance is generally expensive, and the low price is generally poor in performance. In addition, in the case of increasing demand for high-brightness projectors, the heat generated in the internal due to long-time work cannot be dissipated in time, which causes the lens to produce thermal defocus phenomenon, and then causes the picture to be blurred, so it cannot support long-time projection needs and meet the increasing demand of the majority of users for convenient projection. SUMMARY
[0003] Therefore, the present application provides a 2.69-inch LCD projection lens aiming at the deficiencies of the prior art.
[0004] To solve the above technical problems, the technical scheme adopted by the present application is: a 2.69-inch LCD projection lens, comprising a first lens with positive focal power, a second lens with negative focal power and a third lens with positive focal power arranged in order from the object side to the image side, a diaphragm located between the second lens and the third lens, and a Fresnel lens located between the third lens and the image surface.
[0005] Further, the first lens is a double convex lens, the curvature radius range near the object side is 32.2mm~32.3mm, the curvature radius range near the image side is-240.3mm~-240.4mm, the center thickness range is 6.7mm~6.8mm, the refractive index range is 1.61~1.62, and the air gap range between the first lens and the second lens is 4mm~5mm.
[0006] Further, the second lens is a double concave lens, the curvature radius range near the object side is-28.6mm~-28.7mm, the curvature radius range near the image side is 32.5mm~32.6mm, the center thickness range is 2.8mm~2.9mm, the refractive index range is 1.58~1.59, and the air gap range between the second lens and the third lens is 3mm~4mm.
[0007] Further, the third lens is a double-convex lens, the curvature radius range near the object is 43.7 mm~43.8 mm, the curvature radius range near the image is -33.0 mm~-33.1 mm, the central thickness range is 9.1 mm~9.2 mm, the refractive index range is 1.49~1.5, and the air gap range between the third lens and the Fresnel lens is 59 mm~60 mm.
[0008] Further, the Fresnel lens is a plano-concave lens, the object side is a plane, the curvature radius range near the image is -34.4 mm~-34.5 mm, the central thickness range is 1.8 mm~2.0 mm, the refractive index range is 1.49~1.5, and the air gap range between the Fresnel lens and the image plane is 8 mm~9 mm.
[0009] Further, the second lens has a conic constant of -0.29~-0.3 near the object side and a conic constant range of -1.30~-1.31 near the image side.
[0010] Further, the third lens has a conic constant range of 1.80~1.81 near the object side and a conic constant range of -0.45~-0.46 near the image side.
[0011] Further, the resolution is 720P, the luminous flux is 150 lumens, the field of view is 51° or more, the imaging image plane is Φ34.2 mm, and the projection ratio is 1.26 or less.
[0012] Compared with the prior art, the present application has the following advantages: The 2.69-inch LCD projection lens of the present application adopts a 1G2P (1 glass lens and 2 plastic aspheric lenses) optical structure, and through the selection and combination of the lenses, the projection lens has a resolution of 720P, a luminous flux of 150 lumens, a field of view of 51° or more, an imaging image plane of Φ34.2 mm, and a projection ratio of 1.26 or less, and can correct temperature drift and work stably in an environment of -20℃~60℃, has superior imaging performance, does not produce virtual focus, has low price, and can meet the projection needs of more users. BRIEF DESCRIPTION OF DRAWINGS
[0013] Figure 1 The optical system structure diagram of the embodiment of the present application; Figure 2 The MTF (modulation transfer function) curve diagram of the embodiment of the present application under normal temperature (20℃) conditions; Figure 3 The MTF (modulation transfer function) curve diagram of the embodiment of the present application under high temperature (60℃) conditions; Figure 4A diffuser pattern for an embodiment of the present application; Figure 5 A light ray aberration pattern for an embodiment of the present application; In the figure: 1 - first lens, 2 - second lens, 3 - diaphragm, 4 - third lens, 5 - Fresnel lens, 6 - image plane. DETAILED DESCRIPTION
[0014] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions of the embodiments of the present application will be described clearly and completely below with reference to the drawings of the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments of the present application. All other embodiments obtained by those skilled in the art based on the described embodiments of the present application belong to the scope of protection of the present application.
[0015] Embodiment one Reference Figure 1 An LCD projection lens of 2.69 inches includes a first lens 1 with positive focal power, a second lens 2 with negative focal power and a third lens 4 with positive focal power arranged in order from the object side to the image side, a diaphragm 3 is located between the second lens 2 and the third lens 4, and a Fresnel lens 5 is located between the third lens 4 and the image plane 6; the first lens 1 is a glass spherical lens, the second lens 2 and the third lens 4 are both plastic aspherical lenses, and the Fresnel lens 5 is made of plastic.
[0016] The first lens 1 is a biconvex lens, the curvature radius near the object side S1 is 32.2 mm, the curvature radius near the image side is -240.3 mm, the center thickness is 6.7 mm, and the refractive index is 1.61, and the air gap between the vertex of the rear surface of the first lens 1 and the vertex of the front surface of the second lens 2 is 4 mm.
[0017] The second lens 2 is a biconcave lens, the curvature radius near the object side S1 is -28.6 mm, the curvature radius near the image side S2 is 32.5 mm, the center thickness is 2.8 mm, the refractive index is 1.58, and the air gap between the vertex of the rear surface of the second lens 2 and the vertex of the front surface of the third lens 4 is 3 mm.
[0018] The third lens 4 is a biconvex lens, the curvature radius near the object side S1 is 43.7 mm, the curvature radius near the image side S2 is -33.0 mm, the center thickness is 9.1 mm, the refractive index is 1.49, and the air gap between the vertex of the rear surface of the third lens 4 and the vertex of the front surface of the Fresnel lens 5 is 59 mm.
[0019] The Fresnel lens 5 is a plano-concave lens, the plane S1 is close to the object side, the radius of curvature S2 is -34.4 mm close to the image side, the center thickness is 1.8 mm, the refractive index is 1.49, and the air gap between the vertex of the rear surface of the Fresnel lens 5 and the image plane 6 is 8 mm.
[0020] The aspheric parameters of the second lens 2 and the third lens 4 are shown in the following table: lens surface K A4 A6 A8 A10 second lens S1 -0.29 1.83E-05 1.29E-07 -9.86E-10 2.1E-12 S2 -1.30 -1.99E-05 3.64E-07 -1.83E-09 3.74E-12 third lens S1 1.80 -4.13E-05 1.51E-07 -4.91E-10 6.65E-13 S2 -0.45 -9.93E-07 -5.30E-08 2.48E-10 -7.13E-13 The standard equation of the aspheric surface sag is: Wherein, c is the conic curvature, that is, the reciprocal of the radius R, h is the radial coordinate, K is the conic coefficient, and A4-A10 represent the coefficients corresponding to each radial coordinate.
[0021] Figure 2 And Figure 3 The MTF (Modulation Transfer Function) curves of the embodiment of the present application under normal temperature (20 DEG C) and high temperature (60 DEG C) conditions are shown in the figure, wherein the horizontal coordinate represents the spatial frequency, and the unit is line pair per millimeter (lp / mm), and the vertical coordinate represents the MTF value. It can be seen that the MTF difference of the embodiment of the present application under low temperature (20 DEG C) and high temperature (60 DEG C) conditions is small, and basically reaches more than 30%. Figure 4 The diffraction spot diagram of the embodiment of the present application is shown in the figure, and it can be seen from the figure that the diffraction spots of the whole field are within 50 microns. Figure 5 The light aberration diagram of the embodiment of the present application is shown in the figure, and it can be seen from the figure that the aberration distribution corresponding to different wavebands of light is close, similar and compact, and the imaging consistency is good.
[0022] The 2.69-inch LCD projection lens of the embodiment of the present application has a total system length of 95.745 mm, a front aperture of 33.2 mm, a focal length EFL = 72.2 mm, a resolution of 720P, a luminous flux of 150 lumens, a field of view of more than 51 DEG, an imaging image plane Φ of 34.2 mm, and a projection ratio of 1.26 or less.
[0023] In the design process of the present application, two plastic aspheric lenses are used, which greatly increases the image quality and uses cheaper lens materials; and the temperature drift is optimized, so that the thermal expansion coefficients and the refractive index / temperature change coefficients of different glass materials are mutually compensated, the lens can work stably in the temperature range of -20 DEG C to 60 DEG C, and the phenomena of high and low temperature virtual focus and blurred picture do not occur.
[0024] Example two Reference Figure 1The application discloses a 2.69-inch LCD projection lens, which comprises a first lens 1 with positive focal power, a second lens 2 with negative focal power and a third lens 4 with positive focal power arranged in sequence from an object side to an image side, a diaphragm 3 located between the second lens 2 and the third lens 4, and a Fresnel lens 5 located between the third lens 4 and an image plane 6.
[0025] The first lens 1 is a biconvex lens, the curvature radius of the first lens 1 near the object side S1 is 32.25 mm, the curvature radius of the first lens 1 near the image side S2 is -240.35 mm, the central thickness of the first lens 1 is 6.75 mm, the refractive index of the first lens 1 is 1.615, and the air interval between the vertex of the rear surface of the first lens 1 and the vertex of the front surface of the second lens 2 is 4.5 mm.
[0026] The second lens 2 is a biconcave lens, the curvature radius of the second lens 2 near the object side S1 is -28.65 mm, the curvature radius of the second lens 2 near the image side S2 is 32.55 mm, the central thickness of the second lens 2 is 2.85 mm, the refractive index of the second lens 2 is 1.585, and the air interval between the vertex of the rear surface of the second lens 2 and the vertex of the front surface of the third lens 4 is 3.5 mm.
[0027] The third lens 4 is a biconvex lens, the curvature radius of the third lens 4 near the object side S1 is 43.75 mm, the curvature radius of the third lens 4 near the image side S2 is -33.05 mm, the central thickness of the third lens 4 is 9.15 mm, the refractive index of the third lens 4 is 1.495, and the air interval between the vertex of the rear surface of the third lens 4 and the vertex of the front surface of the Fresnel lens 5 is 59.5 mm.
[0028] The Fresnel lens 5 is a plano-concave lens, the object side S1 of the Fresnel lens 5 is a plane, the curvature radius of the image side S2 of the Fresnel lens 5 is -34.45 mm, the central thickness of the Fresnel lens 5 is 1.9 mm, the refractive index of the Fresnel lens 5 is 1.495, and the air interval between the vertex of the rear surface of the Fresnel lens 5 and the image plane 6 is 8.5 mm.
[0029] The conic curvature of the object side S1 of the second lens 2 is -0.295, and the conic curvature of the image side S2 of the second lens 2 is -1.305.
[0030] The conic curvature of the object side S1 of the third lens 4 is 1.805, and the conic curvature of the image side S2 of the third lens 4 is -0.455.
[0031] The aspheric surface parameters of the second lens 2 and the third lens 4 are shown in the following table: lens surface K A4 A6 A8 A10 second lens S1 -0.295 1.84E-05 1.30E-07 -9.87E-10 2.11E-12 S2 -0.305 -2.00E-05 3.65E-07 -1.84E-09 3.75E-12 third lens S1 1.805 -4.14E-05 1.52E-07 -4.92E-10 6.66E-13 S2 -0.455 -9.94E-07 -5.31E-08 2.49E-10 -7.14E-13 The standard equation of the aspheric surface height of the second lens 2 is as follows: wherein: c is the conic constant, h is the radial coordinate, K is the conic constant, A4~A10 are the coefficients corresponding to each radial coordinate.
[0032] The embodiment 2.69 inch LCD projection lens has a resolution of 720P, a light flux of 150 lumens, a field of view of 51° or more, an imaging image plane of 34.2 mm, and a projection ratio of 1.26 or less.
[0033] Embodiment three Reference Figure 1 The embodiment 2.69 inch LCD projection lens comprises a first lens 1 with positive focal power, a second lens 2 with negative focal power, and a third lens 4 with positive focal power arranged in sequence from the object side to the image side, a diaphragm 3 located between the second lens 2 and the third lens 4, and a Fresnel lens 5 located between the third lens 4 and an image plane 6.
[0034] The first lens 1 is a biconvex lens, the curvature radius of the side close to the object S1 is 32.3 mm, the curvature radius of the side close to the image S2 is -240.4 mm, the center thickness is 6.8 mm, and the refractive index is 1.62.
[0035] The second lens 2 is a biconcave lens, the curvature radius of the side close to the object S1 is -28.7 mm, the curvature radius of the side close to the image S2 is 32.6 mm, the center thickness is 2.9 mm, and the refractive index is 1.59.
[0036] The third lens 4 is a biconvex lens, the curvature radius of the side close to the object S1 is 43.8 mm, the curvature radius of the side close to the image S2 is -33.1 mm, the center thickness is 9.2 mm, and the refractive index is 1.5.
[0037] The Fresnel lens 5 is a plano-concave lens, the side close to the object S1 is a plane, the curvature radius of the side close to the image S2 is -34.5 mm, the center thickness is 2.0 mm, and the refractive index is 1.5.
[0038] The conic constant of the side close to the object S1 of the second lens 2 is -0.3, and the conic constant of the side close to the image S2 is -1.31.
[0039] The third lens 4 has a conic curvature of 1.81 near the object side S1 and a conic curvature of -0.46 near the image side S2.
[0040] The aspheric parameters of the second lens 2 and the third lens 4 are shown in the following table: lens surface K A4 A6 A8 A10 second lens S1 -0.30 1.84E-05 1.3E-07 -9.87E-10 2.11E-12 S2 -1.31 -2E-05 3.65E-07 -1.84E-09 3.75E-12 third lens S1 1.81 -4.14E-05 1.52E-07 -4.92E-10 6.66E-13 S2 -0.46 -9.94E-07 -5.31E-08 2.49E-10 -7.14E-13 The standard equation of the aspheric surface height is: Wherein, c is the conic curvature, i.e. the reciprocal of the radius R, h is the radial coordinate, K is the conic coefficient, and A4-A10 represent the coefficients corresponding to each radial coordinate.
[0041] The 2.69-inch LCD projection lens of the embodiment has a resolution of 720P, a luminous flux of 150 lumens, a field of view of 51° or more, an imaging image surface of 34.2mm, and a projection ratio of 1.26 or less.
[0042] The above embodiments are only used to illustrate the technical solutions of the present application but not to limit it. Although the present application has been described in detail with reference to the above embodiments, the ordinary skilled in the art can still modify or equivalently replace the specific embodiments of the present application without departing from the spirit and scope of the present application, and any modification or equivalent replacement without departing from the spirit and scope of the present application is within the protection scope of the claims of the present application.
Claims
1. A 2.69-inch LCD projection lens, characterized in that: It includes a first lens with positive optical power, a second lens with negative optical power, and a third lens with positive optical power arranged sequentially from the object side to the image side. An aperture stop is located between the second and third lenses, and a Fresnel lens is located between the third lens and the image plane. The first lens is a glass spherical lens, the second and third lenses are both plastic aspherical lenses, and the Fresnel lens is made of plastic.
2. The 2.69-inch LCD projection lens according to claim 1, characterized in that: The first lens is a biconvex lens with a radius of curvature of 32.2mm to 32.3mm near the object side, a radius of curvature of -240.3mm to -240.4mm near the image side, a center thickness of 6.7mm to 6.8mm, a refractive index of 1.61 to 1.62, and an air gap of 4mm to 5mm between it and the second lens.
3. The 2.69-inch LCD projection lens according to claim 2, characterized in that: The second lens is a biconcave lens with a radius of curvature of -28.6 mm to -28.7 mm near the object side, a radius of curvature of 32.5 mm to 32.6 mm near the image side, a center thickness of 2.8 mm to 2.9 mm, a refractive index of 1.58 to 1.59, and an air gap of 3 mm to 4 mm between it and the third lens.
4. The 2.69-inch LCD projection lens according to claim 3, characterized in that: The third lens is a biconvex lens with a radius of curvature of 43.7 mm to 43.8 mm near the object side, a radius of curvature of -33.0 mm to -33.1 mm near the image side, a center thickness of 9.1 mm to 9.2 mm, a refractive index of 1.49 to 1.5, and an air gap of 59 mm to 60 mm between it and the Fresnel lens.
5. The 2.69-inch LCD projection lens according to claim 4, characterized in that: The Fresnel lens is a plano-concave lens, with a flat surface near the object plane, a radius of curvature near the image plane ranging from -34.4 mm to -34.5 mm, a center thickness ranging from 1.8 mm to 2.0 mm, a refractive index ranging from 1.49 to 1.5, and an air gap between it and the image plane ranging from 8 mm to 9 mm.
6. The 2.69-inch LCD projection lens according to claim 5, characterized in that: The second lens has a conicity range of -0.29 to -0.3 near the object and a conicity range of -1.30 to -1.31 near the image.
7. The 2.69-inch LCD projection lens according to claim 6, characterized in that: The third lens has a conicity range of 1.80 to 1.81 near the object and a conicity range of -0.45 to -0.46 near the image.
8. The 2.69-inch LCD projection lens according to claim 7, characterized in that: The resolution is 720P, the luminous flux is 150 lumens, the field of view is greater than 51°, the imaging plane is Φ34.2mm, and the throw ratio is less than 1.26.