LCD high-definition projection lens
By optimizing the lens combination and Fresnel lens design, the problem of poor image quality in existing LCD projection lenses has been solved, achieving high-definition projection and miniaturization, providing excellent imaging quality and a low-cost projection solution.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SHENZHEN EVIEWTEK TECH CO LTD
- Filing Date
- 2025-03-24
- Publication Date
- 2026-04-14
AI Technical Summary
Existing LCD projection lenses have poor image quality and cannot meet the 1080P high-definition requirements. At a fixed working distance, the projected image area is small, the brightness is low, and the distortion is obvious. In addition, the lens size is large and difficult to manufacture, which hinders the miniaturization of projectors.
The structure employs a sequential arrangement of a first group of lenses, an aperture, a second group of lenses, and Fresnel lenses. The first lens has positive optical power, the second and third lenses have negative optical power, and the fourth lens has positive optical power. Aberrations are corrected through this lens combination, and Fresnel lenses are used to control the amount of light entering the lens. All lenses are glass spherical surfaces, resulting in a small overall length that meets the requirements of micro-projection.
It achieves high-definition projection with a throw ratio of 1.15, suitable for most viewing needs, with excellent image quality, distortion of less than 0.15%, good color correction, and a resolution of 1920×1080, providing a good viewing experience at a low cost.
Smart Images
Figure CN224122830U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of projection lens technology, and in particular to an LCD high-definition projection lens. Background Technology
[0002] The projection lens is the core component of a projection device. Light passes through a reflective or transmissive light modulation device and then is projected onto the projection screen to form an image.
[0003] With the development of display technology, projectors have become an important part of visual displays. LCD projectors, in particular, are high-tech products resulting from advancements in liquid crystal technology, lighting technology, and integrated circuits. Their key technology is the manufacturing of the liquid crystal panel. LCD projectors utilize the photoelectric effect of liquid crystals—the arrangement of liquid crystal molecules changes under the influence of an electric field, affecting the transmittance or reflectance of the liquid crystal cells, thus influencing their optical properties and producing images with different grayscale levels and colors. Due to its lower cost, LCD technology makes LCD projectors significantly cheaper than DMD projectors.
[0004] Many existing LCD projection lenses have poor image quality that does not meet the requirements of 1080P high definition. At a fixed working distance, the projected image size is also small, the brightness is low, and the distortion is obvious. In addition, the lens size is large and difficult to manufacture, which is not conducive to the miniaturization of projectors. Utility Model Content
[0005] In order to overcome the shortcomings of the prior art, the purpose of this utility model is to provide an LCD high-definition projection lens, which solves the problem of poor image quality of LCD projection lenses in the prior art.
[0006] To achieve the above objectives, this utility model provides the following solution:
[0007] An LCD high-definition projection lens, comprising:
[0008] The first group of lenses, the aperture stop, the second group of lenses, the Fresnel lens, and the image plane are arranged in sequence.
[0009] The image plane is used to emit light, the aperture is used to control the amount of light entering after beam splitting, the first group of lenses and the second group of lenses are both used to correct aberrations, and the Fresnel lens is used for;
[0010] The first group of lenses is a first lens, which is a lens with positive optical power;
[0011] The second group of lenses includes a second lens, a third lens, and a fourth lens, wherein the second lens is a lens with negative optical power, the third lens is a lens with negative optical power, and the fourth lens is a lens with positive optical power.
[0012] The first lens is placed in front of the aperture stop, and the second, third and fourth lenses are placed behind the aperture stop.
[0013] Preferably, the first lens, the second lens, the third lens, and the fourth lens are all spherical lenses.
[0014] Preferably, the ratio of the focal length of the first group of lenses to the focal length of the high-definition projection lens is 0.695, and the ratio of the focal length of the first lens to the focal length of the first group of lenses is 1; the ratio of the focal length of the second group of lenses to the focal length of the high-definition projection lens is -2.409, and the ratio of the focal length of the second lens to the focal length of the second group of lenses is 0.19; the ratio of the focal length of the third lens to the focal length of the second group of lenses is -2.328; and the ratio of the focal length of the fourth lens to the focal length of the second group of lenses is -0.323.
[0015] Preferably, the MTF value of each field of view of the high-definition projection lens is greater than 0.6.
[0016] Preferably, the high-definition projection lens is 2.69 inches with a resolution of 1920mm. 1080p resolution LCD screen.
[0017] Preferably, the high-definition projection lens has a throw ratio of 1.15.
[0018] The present invention discloses the following technical effects:
[0019] This invention provides a high-definition LCD projection lens, comprising: a first group of lenses, an aperture stop, a second group of lenses, a Fresnel lens, and an image plane arranged sequentially; the image plane is used to emit light, the aperture stop is used to control the amount of light entering after beam splitting, and both the first group of lenses and the second group of lenses are used to correct aberrations; the first group of lenses is a first lens, which is a lens with positive optical power; the second group of lenses includes: a second lens, a third lens, and a fourth lens, where the second lens is a lens with negative optical power, the third lens is a lens with negative optical power, and the fourth lens is a lens with positive optical power; the first lens is placed in front of the aperture stop, and the second, third, and fourth lenses are placed behind the aperture stop. The LCD projection lens disclosed in this invention has a throw ratio of 1.15, suitable for most daily viewing needs; the LCD projection lens disclosed in this invention has a small overall length, meeting the needs of miniature projection devices. The LCD projection lens disclosed in this invention has a relative illumination of over 60% across the entire field of view and a full-field MTF of over 0.6, resulting in excellent image quality. Distortion is within 0.15%, and TV distortion is within 0.2%, demonstrating excellent distortion correction. The lens uses only four glass spherical lenses, effectively reducing lens cost and assembly difficulty. The root mean square radius of the dot plot (<30µm) is significantly smaller than the pixel size (31µm), resulting in excellent dot plot performance. The lens exhibits good chromatic aberration correction, with an axial chromatic aberration of less than 20µm, less than one pixel. It also demonstrates good defocus curve correction and consistent image sharpness, contributing to system stability. Finally, the lens achieves a resolution of 1920. 1080p provides a great viewing experience. Attached Figure Description
[0020] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0021] Figure 1 A schematic diagram of an LCD high-definition projection lens structure provided for an embodiment of this utility model;
[0022] Figure 2 Spatial frequency MTF diagram provided for embodiments of this utility model;
[0023] Figure 3A vertical axis color difference diagram provided for an embodiment of this utility model;
[0024] Figure 4 The field curvature evaluation diagram provided for the embodiments of this utility model;
[0025] Figure 5 The distortion evaluation diagram provided for the embodiments of this utility model.
[0026] Explanation of reference numerals in the attached figures:
[0027] 1-First group of lenses, 2-Second group of lenses, 3-Aperture stop, 4-Fresnel lens, 5-Image plane, G1-First lens, G2-Second lens, G3-Third lens, G4-Fourth lens. Detailed Implementation
[0028] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.
[0029] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0030] like Figure 1 As shown, this utility model provides an LCD high-definition projection lens, comprising:
[0031] The first group of lenses 1, the aperture 3, the second group of lenses 2, the Fresnel lens 4, and the image plane 5 are arranged in sequence.
[0032] The image plane 5 is used to emit light, the aperture 3 is used to control the amount of light entering after beam splitting, the first group lens 1 and the second group lens 2 are both used to correct aberrations, the Fresnel lens 4 has the same function as the spherical lens, but it is cheaper and can be made larger, and has a fixed focal length for the imaging optical path.
[0033] The first group of lenses 1 is the first lens G1, which is a lens with positive optical power;
[0034] The second group of lenses 2 includes: a second lens G2, a third lens G3 and a fourth lens G4, wherein the second lens G2 is a lens with negative optical power, the third lens G3 is a lens with negative optical power, and the fourth lens G4 is a lens with positive optical power.
[0035] The first lens G1 is placed in front of the aperture stop 3, and the second lens G2, the third lens G3 and the fourth lens G4 are placed behind the aperture stop 3.
[0036] Specifically, Fresnel lens 4 is made of plastic, while the other lenses are made of glass.
[0037] Furthermore, the first lens G1, the second lens G2, the third lens G3, and the fourth lens G4 are all spherical lenses.
[0038] Furthermore, the ratio of the focal length of the first group lens 1 to the focal length of the high-definition projection lens is 0.695, the ratio of the focal length of the first lens G1 to the focal length of the first group lens 1 is 1; the ratio of the focal length of the second group lens 2 to the focal length of the high-definition projection lens is -2.409, the ratio of the focal length of the second lens G2 to the focal length of the second group lens 2 is 0.19; the ratio of the focal length of the third lens G3 to the focal length of the second group lens 2 is -2.328; the ratio of the focal length of the fourth lens G4 to the focal length of the second group lens 2 is -0.323, and the ratio of the focal length f4 of the Fresnel lens 4 to the focal length f of the objective lens system is approximately 1.143.
[0039] Specifically, the detailed parameters of the objective lens system are shown in Table 1, as follows:
[0040] Table 1. Specific parameters of the objective lens system
[0041]
[0042] The Fresnel lens 4 has a focal length of 70mm at f4.
[0043] Furthermore, the MTF value of each field of view of the high-definition projection lens is greater than 0.6.
[0044] Specifically, such as Figure 2 As shown, MTF (Modulation Transfer Function) is currently the most accurate and scientific evaluation standard for lenses. The vertical axis represents contrast ratio; the closer it is to 1, the better the lens image quality. The horizontal axis represents resolution, measured in line pairs per millimeter. The image source pixel size used in this embodiment is 31µm, corresponding to a design resolution of 8.65 line pairs per millimeter. Projection lenses generally require an MTF value of at least 0.3 for each field of view at the design resolution, while the MTF values for each field of view in this embodiment are all above 0.6.
[0045] Furthermore, such as Figure 3The figure shows the vertical axis chromatic aberration of the lens, with the vertical axis representing the image height field of view and the horizontal axis representing the numerical value in micrometers. The figure plots the chromatic aberration values for each field of view between blue, red, and green light (dominant wavelengths) based on the dominant wavelength. Projection lenses generally require the chromatic aberration value to be within the size of one image source pixel. In this embodiment, the axial chromatic aberration is controlled within 10µm, which is less than one pixel size (pixel size 31µm).
[0046] like Figure 4-5 As shown, Figure 4 This is a performance evaluation chart. Figure 5 This is a distortion evaluation graph. The vertical axis represents the field of view of the lens. The horizontal axis of the field curvature graph represents the magnitude of the field curvature value, and the horizontal axis of the distortion graph represents the distortion value. Distortion is a very important indicator for projection lenses, generally requiring control within 3%, while TV distortion is required to be controlled within 1%. The system distortion of this embodiment is within 0.15%, and the TV distortion value is also within 0.2%, indicating excellent distortion properties of the system.
[0047] Furthermore, the lens has a projection ratio of 1.15; an effective focal length of 61.22mm and an f / n=2.6; and a 2.69-inch, 1920mm lens. A 1080 resolution LCD screen; the lens uses Fresnel lens 4, which can effectively converge the principal ray angle of the lens.
[0048] More specifically, in the implementation, the optical lens satisfies the following condition:
[0049] 0.65 <EPND / IH<0.71 (1)
[0050] Wherein, EPND represents the aperture of the optical lens, and IH represents the actual half-image height of the optical lens.
[0051] When condition (1) is met, a reasonable balance between the light transmission of the lens and the size of the imaging surface 5 can be achieved.
[0052] In the implementation method, the optical lens satisfies the following condition:
[0053] 0.03mm -1 <T L / f / IH<0.05mm -1 (2)
[0054] Among them, T L The optical total length of the optical lens is represented by f, the effective focal length of the optical lens is represented by f, and the actual half-image height of the optical lens is represented by IH.
[0055] When condition (2) is satisfied, the relationship between the total length of the lens and the resolving power can be reasonably balanced.L When the / f / IH value exceeds the upper limit, the overall length of the lens is too large, or in other words, if the overall length is shortened, the image height will be insufficient; T L When the value of / f / IH exceeds the lower limit, the lens aberration correction becomes difficult due to the excessive optical focal length of each lens, and the resolving power decreases significantly.
[0056] In the implementation method, the optical lens satisfies the following condition:
[0057] 55mm <IH / tanθ<65mm (3)
[0058] Wherein, IH represents the actual half-image height of the optical lens, and θ represents the half-field angle of the optical lens.
[0059] When condition (3) is met, the distortion of the optical lens can be reasonably limited, reducing the difficulty of distortion correction. When the value of IH / tanθ exceeds the lower limit, the distortion of the lens will increase in the negative direction; when the value of IH / tanθ exceeds the upper limit, the distortion of the lens will increase in the positive direction.
[0060] In the implementation method, the optical lens satisfies the following condition:
[0061] CRA < 3° (6)
[0062] Wherein, CRA represents the principal ray incident angle of the optical lens on the imaging plane 5.
[0063] When condition (6) is met, it can be well matched with the LCD screen and achieve good projection effect.
[0064] This invention proposes an LCD high-definition objective lens system for micro-projection, which comprehensively considers and balances manufacturing, cost, image quality, projection brightness, etc., and has a series of advantages such as small projection ratio, high imaging quality, few lenses, small distortion, reasonable tolerance, and low cost.
[0065] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.
[0066] This document uses specific examples to illustrate the principles and implementation methods of this utility model. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this utility model. Furthermore, those skilled in the art will recognize that, based on the ideas of this utility model, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this utility model.
Claims
1. An LCD high-definition projection lens, characterized in that, include: The first group of lenses, the aperture stop, the second group of lenses, the Fresnel lens, and the image plane are arranged in sequence. The image plane is used to emit light, the aperture is used to control the amount of light entering after beam splitting, the first group of lenses and the second group of lenses are both used to correct aberrations, and the Fresnel lens is used to provide a fixed focal length for imaging; The first group of lenses is a first lens, which is a lens with positive optical power; The second group of lenses includes a second lens, a third lens, and a fourth lens, wherein the second lens is a lens with negative optical power, the third lens is a lens with negative optical power, and the fourth lens is a lens with positive optical power. The first lens is placed in front of the aperture stop, and the second, third and fourth lenses are placed behind the aperture stop.
2. The LCD high-definition projection lens according to claim 1, characterized in that, The first lens, the second lens, the third lens, and the fourth lens are all spherical lenses.
3. The LCD high-definition projection lens according to claim 1, characterized in that, The ratio of the focal length of the first group of lenses to the focal length of the high-definition projection lens is 0.695, and the ratio of the focal length of the first lens to the focal length of the first group of lenses is 1; the ratio of the focal length of the second group of lenses to the focal length of the high-definition projection lens is -2.409, and the ratio of the focal length of the second lens to the focal length of the second group of lenses is 0.19; the ratio of the focal length of the third lens to the focal length of the second group of lenses is -2.328; and the ratio of the focal length of the fourth lens to the focal length of the second group of lenses is -0.
323.
4. The LCD high-definition projection lens according to claim 1, characterized in that, The MTF value of each field of view of the high-definition projection lens is greater than 0.
6.
5. The LCD high-definition projection lens according to claim 1, characterized in that, The high-definition projection lens uses a 2.69-inch LCD screen with a resolution of 1920*1080.
6. The LCD high-definition projection lens according to claim 1, characterized in that, The high-definition projection lens has a throw ratio of 1.15.