Large-aperture LCD projection lens
By adopting a four-piece lens structure, combining glass spherical and plastic aspherical lenses, and Fresnel lenses, the problems of high cost and difficult performance of LCD projection lenses in the prior art are solved, and high-resolving image, large aperture and low-cost effects are achieved.
Patent Information
- Application Number
- CN202420379412.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-02-29
- Publication Date
- 2025-03-25
- Estimated Expiration
- 2034-02-28
AI Technical Summary
While ensuring high resolution and brightness, existing LCD projection lenses are difficult to effectively control the cost, and the lens structure is complex, making it difficult to meet the needs of low cost and high performance.
An LCD projection lens adopting a four-piece lens structure, wherein the first lens is a glass spherical lens, the second lens and the third lens are plastic aspherical lenses, and the fourth lens is a plastic aspherical Fresnel lens. By optimizing the structure and combination of the lenses, the effect of large aperture and high resolution is achieved.
It realizes the advantages of high-resolving imaging, large aperture, compact structure, and adapts to high and low temperatures, while reducing costs and effectively correcting aberrations in optical systems. It is suitable for LCD projection equipment.
Smart Images
Figure CN222672034U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of projection lenses, in particular to a large aperture LCD projection lens. Background Art
[0002] In recent years, as the brightness of LCD screens has increased, the demand for low-cost LCD projection has increased; as the demand for LCD projection has increased, the demand for high-resolution, miniaturized, and large-aperture projection lenses has increased. Currently, in order to ensure the resolution and brightness requirements, lenses on the market usually use multiple glass lenses, and the cost of lenses is difficult to effectively control. It is very necessary to develop a product with low cost and that can meet performance requirements. Utility Model Content
[0003] The purpose of the utility model is to provide a large aperture LCD projection lens in order to solve the above problems.
[0004] The utility model achieves the above-mentioned purpose through the following technical solutions:
[0005] A large aperture LCD projection lens comprises a first lens, a second lens, a third lens and a fourth lens arranged in sequence from an object side to an image side, an aperture is arranged between the second lens and the third lens, a surface of the first lens close to the object side is a convex surface, and the other surface of the first lens is a concave surface, a surface of the second lens close to the first lens is a concave surface, and the other surface of the second lens is a convex surface, a surface of the third lens close to the second lens is a convex surface, and the other surface of the third lens is a concave surface, and the fourth lens is a Fresnel lens; the distance from the rear vertex of the lens composed of the first lens, the second lens, the aperture, the third lens and the fourth lens to the fourth lens is L, and L>83.
[0006] Preferably, the lens aperture Fno. formed by the first lens, the second lens, the aperture stop, the third lens and the fourth lens is less than 2.8.
[0007] Preferably, the distance from the fourth lens to the LCD is M, 9<M<13.
[0008] Preferably, the first lens is a glass spherical lens, and the second lens and the third lens are both plastic aspherical lenses.
[0009] Preferably, the focal length of the first lens is f1, and the focal length of the lens optical system composed of the first lens, the second lens, the aperture, the third lens and the fourth lens is f, 1<|f1 / f|<1.1.
[0010] Preferably, the transmittance of the lens consisting of the first lens, the second lens, the aperture, the third lens and the fourth lens is TR, 1.2<|TR|<1.35.
[0011] The beneficial effects are:
[0012] The utility model adopts a four-lens structure, the second lens L2 and the third lens L3 are both plastic aspherical lenses, the first lens L1 is a glass spherical lens, and the fourth lens L4 is a plastic aspherical Fresnel lens. The obtained LCD projection lens has the advantages of high resolution, large aperture, compact structure, high and low temperature, can effectively correct the aberration in the optical system, and at the same time, it is lower in cost than the LCD projection lens in the prior art and can be applied to LCD projection equipment. BRIEF DESCRIPTION OF THE DRAWINGS
[0013] In order to more clearly illustrate the embodiments of the utility model 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 utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.
[0014] Figure 1 It is a schematic diagram of the composition structure of the LCD projection lens of the utility model.
[0015] Figure 2 It is a schematic diagram of spherical aberration of the LCD projection of the utility model at room temperature.
[0016] Figure 3 It is a schematic diagram of LCD projection astigmatism of the utility model.
[0017] Figure 4 This is a schematic diagram of LCD projection distortion of the utility model.
[0018] Figure 5 It is a schematic diagram of the Rayfan of the LCD projection of the utility model at room temperature.
[0019] The following are the descriptions of the reference numerals:
[0020] 1 is the first lens, 2 is the second lens, 3 is the aperture, 4 is the third lens, and 5 is the fourth lens. DETAILED DESCRIPTION
[0021] The following is combined with Figure 1-5 , the technical solution of the utility model is further explained:
[0022] like Figure 1-Figure 5As shown, the utility model discloses a large aperture LCD projection lens, comprising a first lens 1, a second lens 2, a third lens 4 and a fourth lens 5 arranged in sequence from the object side to the image side, an aperture 3 is arranged between the second lens 2 and the third lens 4, and the lens aperture Fno. <2.8 composed of the first lens 1, the second lens 2, the aperture 3, the third lens 4 and the fourth lens 5. In other words, a 4-lens structure is adopted, and the fourth lens adopts a plastic aspherical Fresnel lens. The obtained LCD projection lens has the advantages of high resolution, large aperture, compact structure, high and low temperature, and is also lower in cost than the existing LCD projection lens, and the lens aperture size meets the lens brightness requirements.
[0023] It should be noted that the aspherical Fresnel lens can improve the overall resolution of the lens.
[0024] Specifically, a surface of the first lens 1 close to the object side is convex, and the other surface of the first lens 1 is concave; a surface of the second lens 2 close to the first lens 1 is concave, and the other surface of the second lens 2 is convex; a surface of the third lens 4 close to the second lens 2 is convex, and the other surface of the third lens 4 is concave; and the fourth lens 5 is a Fresnel lens.
[0025] It should be noted that the first lens 1 is a glass spherical lens, and the second lens 2 and the third lens 4 are both plastic aspherical lenses.
[0026] In some embodiments, the distance from the back vertex of the lens composed of the first lens 1, the second lens 2, the aperture 3, the third lens 4 and the fourth lens 5 to the fourth lens is L, and L>83. In other words, the distance from the back vertex of the lens to the Fresnel lens determines the optical machine back focus position, and if the back focus is too small, the optical path will be interfered by the mechanism.
[0027] In some embodiments, the distance between the fourth lens 5 and the LCD is M, 9<M<13. That is, the distance between the Fresnel lens and the LCD is determined by the optical machine, and too large or too small will be detrimental to the resolution.
[0028] In some embodiments, the focal length of the first lens 1 is f1, and the focal length of the lens optical system composed of the first lens 1, the second lens 2, the aperture 3, the third lens 4 and the fourth lens 5 is f, 1<|f1 / f|<1.1. In other words, the focal length of the lens is determined by the structure of the front and rear surfaces of the lens, and the focal length of the lens reflects the overall situation of the front and rear surfaces of the lens after the combination, which is a structural parameter of the lens. For a lens that meets the above-mentioned restrictions, the variation of high and low temperature analysis can be effectively corrected, and in this embodiment, preferably |f1 / f|=1.05.
[0029] In some embodiments, the transmittance of the lens composed of the first lens 1, the second lens 2, the aperture 3, the third lens 4 and the fourth lens 5 is TR, 1.2<|TR|<1.35. In other words, the smaller the lens transmittance, the larger the projected image at the same distance, and the higher the design difficulty, and thus the preferred embodiment of |TR|=1.24.
[0030] Specifically, the basic lens data in this embodiment are shown in the following table:
[0031]
[0032] Table 1
[0033] In the above table, the surface numbers use the object surface of the first lens L1, which is the structural element closest to the object side, as the first surface, and are arranged in sequence along the image direction. The radius of curvature R represents the value of the radius of curvature of the corresponding surface, in mm. The surface interval D represents the lens thickness of the corresponding surface or the interval value between the lenses, in mm. The above table also gives the refractive index Nd and Abbe constant Vd of the lens relative to d light (wavelength of 587.6nm).
[0034] Further, in this embodiment, the second lens L2 and the third lens L3 are both aspherical lenses. The coefficients of the aspherical lenses are based on the center of the lens surface as the origin, the optical axis as the x-axis, and the aspherical surface shape expression of the lens surface satisfies the following formula: X=(CY^2) / (1+√(1-(k+1)C^2Y^2))+bY^4+cY^6+dY^8+eY^10+fY^12+gY^14+hY^16,
[0035] Among them, X is the depth of the aspheric lens, in mm, Y is the distance from the optical axis to the lens surface, in mm, C is the radius of curvature of the aspheric lens, C = 1 / R, k is the cone constant, b, c, d, e, f, g, h are the coefficients of the aspheric lens, and the specific parameters of the coefficients are shown in the following table:
[0036]
[0037] Table 2
[0038] Specifically, the optical system parameters of this embodiment are shown in the following table:
[0039] f FNO. TR TTL LCD Size 80 2.7 1.31 99.6 2.69 inches
[0040] Table 3
[0041] In the above table, the unit of paraxial focal length f is mm, FNO. is the lens aperture value, ω in the angle of view 2ω represents half the angle of view, and the unit of optical total length TTL is mm.
[0042] The LCD projection lens of this embodiment is tested at room temperature and the phase difference diagram is recorded. Figure 2-Figure 5 The spherical aberration diagram, astigmatism diagram, distortion diagram and Rayfan diagram at room temperature are shown in Table 3 and the attached figure. Figure 2-5 It can be seen that the various aberrations of the LCD projection lens of this embodiment are well corrected, and it can be applied to LCD projection equipment. In summary, the utility model provides a high-resolution LCD projection lens, which adopts a four-lens structure, the first lens L1, the second lens L2, and the third lens L3 are all plastic aspheric lenses, and the fourth lens L4 is a plastic aspheric Fresnel lens. The obtained LCD projection lens has the advantages of high resolution, large aperture, compact structure, high and low temperature, can effectively correct the aberrations in the optical system, and at the same time, it is lower in cost than the LCD projection lens of the prior art, and can be applied to LCD projection equipment.
[0043] The above shows and describes the basic principle, main features and advantages of the utility model. Those skilled in the art should understand that the utility model is not limited by the above embodiments, and the above embodiments and descriptions are only for explaining the principle of the utility model. Without departing from the spirit and scope of the utility model, the utility model may have various changes and improvements, and these changes and improvements fall within the scope of the utility model to be protected.
Claims
1. A large aperture LCD projection lens, characterized in that: The invention comprises a first lens, a second lens, a third lens and a fourth lens which are arranged in sequence from the object side to the image side, an aperture is arranged between the second lens and the third lens, a surface of the first lens close to the object side is a convex surface, and the other surface of the first lens is a concave surface, a surface of the second lens close to the first lens is a concave surface, and the other surface of the second lens is a convex surface, a surface of the third lens close to the second lens is a convex surface, and the other surface of the third lens is a concave surface, and the fourth lens is a Fresnel lens; a distance from a rear vertex of a lens composed of the first lens, the second lens, the aperture, the third lens and the fourth lens to the fourth lens is L, and L>83.
2. The large aperture LCD projection lens according to claim 1, characterized in that: The lens aperture Fno. formed by the first lens, the second lens, the aperture, the third lens and the fourth lens is less than 2.
8.
3. The large aperture LCD projection lens according to claim 1, characterized in that: The distance between the fourth lens and the LCD is M, 9<M<13.
4. The large aperture LCD projection lens according to claim 1, characterized in that: The first lens is a glass spherical lens, and the second lens and the third lens are both plastic aspherical lenses.
5. The large aperture LCD projection lens according to claim 1, characterized in that: The focal length of the first lens is f1, and the focal length of the lens optical system composed of the first lens, the second lens, the aperture, the third lens and the fourth lens is f, 1<|f1 / f|<1.
1.
6. The large aperture LCD projection lens according to claim 1, wherein: The transmittance of the lens composed of the first lens, the second lens, the aperture, the third lens and the fourth lens is TR, 1.2<|TR|<1.35.