Short-focus projection lens with partial off-axis
By using a hybrid design of glass spherical mirrors and plastic aspherical mirrors, the problems of limited focal length and high cost of LCD lenses were solved, achieving focal length reduction and off-axis improvement, optimizing imaging effects and reducing production costs.
Patent Information
- Application Number
- CN202423209529.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-25
- Publication Date
- 2025-11-18
- Estimated Expiration
- 2034-12-25
AI Technical Summary
In the existing technology, the focal length of LCD lenses cannot be further shortened without increasing the number of lenses, and aberrations cannot be corrected, resulting in increased production costs. Furthermore, setting the off-axis increases the size and number of lenses, leading to high overall costs.
By employing a hybrid design of glass spherical mirrors and plastic aspherical mirrors and through the rational combination of materials, a short-throw projection lens with partial off-axis is designed to meet specific focal length and off-axis relationships and optimize imaging performance.
It achieves a 25% reduction in focal length and a 30% improvement in off-axis projection, enabling the projection of large images from short distances, optimizing image quality, reducing production costs, and meeting imaging requirements.
Smart Images
Figure CN223565977U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model belongs to the projection technical field, concretely relates to a short focus projection lens with partial off-axis. BACKGROUND
[0002] Short focus lens refers to the lens with short focal length, it can project large size image in short distance, it is very beneficial for the environment with limited space, short focus projection lens with partial off-axis refers to a special designed projection lens, it can project in the angle deviating from optical axis, and has short focal length, can project large image in short distance.
[0003] Problems of prior art:
[0004] At present, the focal length of LCD lens cannot be shortened again without increasing the number of lenses, and the aberration cannot be corrected, if short focus lens is needed, the number of lenses must be increased, but the production cost will increase rapidly, and the size and number of lenses will also increase due to the setting of off-axis, so the overall cost is high. UTILITY MODEL CONTENT
[0005] The utility model aims at providing a short focus projection lens with partial off-axis, which can adopt the method of mixing glass spherical lens and plastic aspherical lens, reduce the focal length by reasonable collocation of materials, and has 30% off-axis, so that the better experience effect of projecting large screen with partial off-axis in short distance is realized.
[0006] The technical scheme adopted by the utility model is as follows:
[0007] A short focus projection lens with partial off-axis comprises a first lens, a second lens, a third lens, a Fresnel lens and an LCD display screen arranged in sequence along the optical axis from the object side to the image side, the first lens is a convex-concave positive focal power spherical lens, the second lens is a convex-concave negative focal power aspherical lens, and the third lens is a convex-concave positive focal power aspherical lens.
[0008] The material of the first lens is glass, and the materials of the second lens and the third lens are plastic.
[0009] The focal length of the first lens is positive, the focal length of the second lens is negative, and the focal length of the third lens is positive.
[0010] The first lens and the short focus projection lens with partial off-axis satisfy the following relationship: 0.3<|f1 / f|<0.8, wherein f1 is the focal length of the first lens, and f is the optical system focal length of the short focus projection lens with partial off-axis.
[0011] The first lens, the second lens and the short-focus projection lens with partial off-axis satisfy the following relationship: 2.2<|f12 / f|<3.0, wherein f12 is the combined focal length of the first lens and the second lens, and f is the optical system focal length of the short-focus projection lens with partial off-axis.
[0012] The third lens and the short-focus projection lens with partial off-axis satisfy the following relationship: 0.8<|f3 / f|<1.5, wherein f3 is the focal length of the third lens, and f is the optical system focal length of the short-focus projection lens with partial off-axis.
[0013] The Abbe number of the first lens is greater than 35, the Abbe number of the second lens is less than 35, and the Abbe number of the third lens is greater than 50.
[0014] The technical effects achieved by the utility model are as follows:
[0015] The utility model discloses, the optical system of short-focus projection lens with partial off-axis adopts the method that glass spherical mirror and plastic aspherical mirror are mixed, and the focal length can be reduced through the reasonable collocation and optimization of material, and the projection ratio reaches 0.85:1, and has 30% off-axis, and the focal length of fixed focus lens in the prior art is reduced by 25%, and the off-axis is improved from 0 to 30%, and the better experience effect of projecting the large picture with partial off-axis in short distance is realized, and the resolving power meets the imaging requirement. BRIEF DESCRIPTION OF DRAWINGS
[0016] Figure 1 It is the structural schematic diagram provided by the embodiment of the utility model.
[0017] In the drawings, the component list represented by each sign is as follows:
[0018] 1, first lens;2, second lens;3, third lens;4, fresnel mirror;5, LCD display screen. DETAILED DESCRIPTION
[0019] In order to make the purpose and the advantage of the utility model more clear and obvious, the utility model is specifically explained below combining with the embodiment. It should be understood that the following text is only used to describe one or several specific implementation manners of the utility model, and does not strictly limit the protection scope of the utility model.
[0020] As Figure 1 Shown, a kind of short-focus projection lens with partial off-axis, including first lens 1, second lens 2, third lens 3, fresnel mirror 4 and LCD display screen 5 in order along optical axis from object side to image, first lens 1 is convex-concave positive power spherical lens, second lens 2 is convex-concave negative power aspherical lens, third lens 3 is concave-convex positive power aspherical lens.
[0021] Refer to the drawingsFigure 1 The material of the first lens 1 is glass, the materials of the second lens 2 and the third lens 3 are plastic, the focal length of the first lens 1 is positive, the focal length of the second lens 2 is negative, the focal length of the third lens 3 is positive, the Abbe number of the first lens 1 is greater than 35, the Abbe number of the second lens 2 is less than 35, and the Abbe number of the third lens 3 is greater than 50.
[0022] According to the above structure, the image side surface of the first lens 1 can be convex, concave or flat, the object side surface of the second lens 2 and the third lens 3 can be convex, concave or flat, the optical power of the first lens 1 is positive, the optical power of the second lens 2 is negative, and the optical power of the third lens 3 is positive. The optical power is equal to the difference between the image side beam convergence and the object side beam convergence, which represents the ability of the optical system to deflect light rays. When the optical power is positive, the refraction of light rays is convergent. When the optical power is negative, the refraction of light rays is divergent. A diaphragm is also provided between the image side surface of the second lens 2 and the object side surface of the third lens 3. The diaphragm optimizes the performance of the optical system, improves image quality, and ensures that the system works according to the design intention. In the optical system, the selection of Abbe number of different lenses has an important influence on the overall imaging performance. Abbe number is a parameter for measuring the dispersion characteristics of optical materials. The higher the value, the lower the dispersion. The lower the value, the higher the dispersion. The first lens 1 has low dispersion, so it can reduce chromatic aberration in the optical system, which helps to maintain the clarity and contrast of the image. The second lens 2 has high dispersion, which may introduce certain chromatic aberration to balance other aberrations in the system. The third lens 3 has very low dispersion, which helps to provide very clear images, especially in wide-band spectral imaging, which can reduce the impact of chromatic aberration on image quality. By combining lenses with different Abbe numbers, different Abbe number lenses can compensate for other types of aberrations, allowing precise control of the chromatic aberration of the entire system and achieving optimized imaging performance.
[0023] According to the above structure, the image side surface of the first lens 1 can be convex, concave or flat, the object side surface of the second lens 2 and the third lens 3 can be convex, concave or flat, the optical power of the first lens 1 is positive, the optical power of the second lens 2 is negative, and the optical power of the third lens 3 is positive. The optical power is equal to the difference between the image side beam convergence and the object side beam convergence, which represents the ability of the optical system to deflect light rays. When the optical power is positive, the refraction of light rays is convergent. When the optical power is negative, the refraction of light rays is divergent. A diaphragm is also provided between the image side surface of the second lens 2 and the object side surface of the third lens 3. The diaphragm optimizes the performance of the optical system, improves image quality, and ensures that the system works according to the design intention. In the optical system, the selection of Abbe number of different lenses has an important influence on the overall imaging performance. Abbe number is a parameter for measuring the dispersion characteristics of optical materials. The higher the value, the lower the dispersion. The lower the value, the higher the dispersion. The first lens 1 has low dispersion, so it can reduce chromatic aberration in the optical system, which helps to maintain the clarity and contrast of the image. The second lens 2 has high dispersion, which may introduce certain chromatic aberration to balance other aberrations in the system. The third lens 3 has very low dispersion, which helps to provide very clear images, especially in wide-band spectral imaging, which can reduce the impact of chromatic aberration on image quality. By combining lenses with different Abbe numbers, different Abbe number lenses can compensate for other types of aberrations, allowing precise control of the chromatic aberration of the entire system and achieving optimized imaging performance.
[0024] Referring to the accompanying drawings, Figure 1 The first lens 1 and the short-focus projection lens with partial off-axis satisfy the following relationship: 0.3<|f1 / f|<0.8, where f1 is the focal length of the first lens 1, and f is the optical system focal length of the short-focus projection lens with partial off-axis. The first lens 1, the second lens 2 and the short-focus projection lens with partial off-axis satisfy the following relationship: 2.2<|f12 / f|<3.0, where f12 is the combined focal length of the first lens 1 and the second lens 2, and f is the optical system focal length of the short-focus lens with partial off-axis. The third lens 3 and the short-focus projection lens with partial off-axis satisfy the following relationship: 0.8<|f3 / f|<1.5, where f3 is the focal length of the third lens 3, and f is the optical system focal length of the short-focus lens with partial off-axis.
[0025] According to the above structure, the first lens 1 and the short-focus projection lens with partial off-axis meet the following relationship: 0.3<|f1 / f|<0.8, wherein f1 is the focal length of the first lens 1, and f is the optical system focal length of the short-focus projection lens with partial off-axis, wherein the first lens 1 is used for collecting light, and is suitable for a lens with a large field of view, and since the shape of the lens has an important influence on distortion and imaging effect, in order to make the imaging effect better, the design value of the first lens 1 needs to meet 5<|CT1 / ET1|<10, wherein CT1 is the central thickness of the first lens 1, and ET1 is the edge thickness of the first lens 1 along the axial direction, the first lens 1, the second lens 2 and the short-focus projection lens with partial off-axis meet the following relationship: 2.2<|f12 / f|<3.0, and the third lens 3 and the short-focus projection lens with partial off-axis meet the following relationship: 0.8<|f3 / f|<1.5, wherein f3 is the focal length of the third lens 3, and f is the optical system focal length of the short-focus projection lens with partial off-axis, and within this range, coma, astigmatism, field curvature and other aberrations can be well corrected.
[0026] The working principle of the utility model is: the image side of the first lens 1 can be convex, concave or flat, the object side of the second lens 2 and the third lens 3 can be convex, concave or flat, the refractive power of the first lens 1 is positive, the refractive power of the second lens 2 is negative, the refractive power of the third lens 3 is positive, the refractive power is equal to the difference between the converging degree of the image side light bundle and the converging degree of the object side light bundle, which represents the ability of the optical system to deflect light, when the refractive power is positive, the refraction of light is convergent, when the refractive power is negative, the refraction of light is divergent, a diaphragm is further arranged between the image side of the second lens 2 and the object side of the third lens 3, the performance of the optical system is optimized through the diaphragm, the image quality is improved, and the system works according to the design intention, the first lens 1 and the short-focus projection lens with partial off-axis meet the following relationship: 0.3<|f1 / f|<0.8, wherein f1 is the focal length of the first lens 1, and f is the optical system focal length of the short-focus projection lens with partial off-axis, wherein the first lens 1 is used for collecting light, and is suitable for a lens with a large field of view, and since the shape of the lens has an important influence on distortion and imaging effect, in order to make the imaging effect better, the design value of the first lens 1 needs to meet 5<|CT1 / ET1|<10, wherein CT1 is the central thickness of the first lens 1, and ET1 is the edge thickness of the first lens 1 along the axial direction, the first lens 1, the second lens 2 and the short-focus projection lens with partial off-axis meet the following relationship: 2.2<|f12 / f|<3.0, and the third lens 3 and the short-focus projection lens with partial off-axis meet the following relationship: 0.8<|f3 / f|<1.5, wherein f3 is the focal length of the third lens 3, and f is the optical system focal length of the short-focus projection lens with partial off-axis, and within this range, coma, astigmatism, field curvature and other aberrations can be well corrected.
[0027] The above merely describes preferred embodiments of the present application, and it should be noted that, for those skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should also be considered as the protection scope of the present application. The structures, devices and operation methods not specifically described and explained in the present application are implemented according to conventional means in the art, unless otherwise specified and limited.
Claims
1. A short-throw projection lens with partial off-axis, comprising a first lens (1), a second lens (2), a third lens (3), a Fresnel lens (4), and an LCD display screen (5) arranged sequentially along the optical axis from object to image, characterized in that: The first lens (1) is a spherical lens with positive optical power, the second lens (2) is an aspherical lens with negative optical power, and the third lens (3) is an aspherical lens with positive optical power.
2. A short-throw projection lens with partial off-axis as described in claim 1, characterized in that: The first lens (1) is made of glass, and the second lens (2) and the third lens (3) are made of plastic.
3. A short-throw projection lens with partial off-axis as described in claim 1, characterized in that: The focal length of the first lens (1) is positive, the focal length of the second lens (2) is negative, and the focal length of the third lens (3) is positive.
4. A short-throw projection lens with partial off-axis as described in claim 1, characterized in that: The first lens (1) and the short-throw projection lens with partial off-axis satisfy the following relationship: 0.3 < |f1 / f| < 0.8, where f1 is the focal length of the first lens (1) and f is the focal length of the optical system of the short-throw projection lens with partial off-axis.
5. A short-throw projection lens with partial off-axis as described in claim 1, characterized in that: The first lens (1), the second lens (2) and the short-focal-length projection lens with partial off-axis satisfy the following relationship: 2.2 < |f12 / f| < 3.0, where f12 is the combined focal length of the first lens (1) and the second lens (2), and f is the focal length of the optical system of the short-focal-length lens with partial off-axis.
6. A short-throw projection lens with partial off-axis as described in claim 1, characterized in that: The third lens (3) and the short-focal-length projection lens with partial off-axis satisfy the following relationship: 0.8 < |f3 / f| < 1.5, where f3 is the focal length of the third lens (3) and f is the focal length of the optical system of the short-focal-length lens with partial off-axis.
7. A short-throw projection lens with partial off-axis as described in claim 1, characterized in that: The Abbe number of the first lens (1) is greater than 35, the Abbe number of the second lens (2) is less than 35, and the Abbe number of the third lens (3) is greater than 50.