Three-piece liquid crystal display (LCD) projection lens
By designing a three-piece LCD projection lens and using specific lens combinations and apertures, the problems of high cost and poor imaging effects in the prior art are solved, and low-cost and high-quality image display is achieved.
Patent Information
- Application Number
- CN202421636020.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-11
- Publication Date
- 2025-05-02
- Estimated Expiration
- 2034-07-11
AI Technical Summary
While pursuing imaging quality and brightness, existing LCD projection lenses have high costs and are usually poor in imaging effects, making it difficult to achieve a balance of cost, brightness, image quality and resolution.
A three-piece LCD projection lens is designed, using a coaxially arranged first group lens with positive power, a diaphragm, a second group lens with negative power, a film sheet with positive power and an imaging surface. Only three lenses are used to achieve a balance of imaging brightness, cost, image quality and resolution.
It realizes low-cost and high-quality image display, with small number of lenses, small size, and easy to manufacture, while providing high-quality imaging effects.
Smart Images
Figure CN222825727U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of projection lenses, in particular to a three-piece LCD projection lens. Background Art
[0002] The projection lens is a crucial component in the projection equipment. It adjusts the light through a reflective or transmissive light modulator and projects it onto the projection screen to form an image. At present, the projectors on the market are mainly classified into LCD, DLP, LCOS and other types according to technology. LCD projectors have quickly occupied a place in the low-end and mid-end consumer market with their mature technology and low cost.
[0003] LCD projectors use the photoelectric effect of liquid crystal, that is, the arrangement of liquid crystal molecules changes under the action of an electric field, thereby adjusting the transmittance or reflectivity of the liquid crystal unit to achieve image display with different gray levels and colors. However, many existing LCD projection lenses use a universal design to reduce costs, resulting in poor imaging effects. Other projection lenses usually use more and more expensive lenses in pursuit of image quality and brightness.
[0004] Therefore, it is necessary to design a new projection lens that can balance the requirements of imaging brightness, cost, image quality and resolution, be easy to manufacture, small in size and low in cost, and at the same time provide high-quality image display effects. Utility Model Content
[0005] The utility model aims to overcome the defects of the prior art and provide a three-piece LCD projection lens.
[0006] To solve the above technical problems, the purpose of the utility model is achieved through the following technical solutions: to provide a three-piece LCD projection lens, comprising: a first group of lenses with positive focal length, an aperture, a second group of lenses with negative focal length, a film with positive focal length, and an imaging surface.
[0007] A further technical solution is: the first group of lenses includes a first lens with positive optical power.
[0008] A further technical solution is as follows: the second lens group includes a second lens with negative focal power and a third lens with positive focal power; the second lens is located between the aperture and the third lens; and the third lens is located between the second lens and the film.
[0009] A further technical solution is that the first lens, the second lens and the third lens are spherical lenses respectively.
[0010] A further technical solution is: the ratio of the focal length of the first group of lenses to the focal length of the objective lens system is 0.478.
[0011] A further technical solution is: the ratio of the focal length of the second lens group to the focal length of the objective lens system is -1.087.
[0012] A further technical solution is: the ratio of the focal length of the second lens to the focal length of the second group of lenses is 3.787.
[0013] A further technical solution is: the ratio of the focal length of the third lens to the focal length of the second group of lenses is -8.492.
[0014] A further technical solution is: the ratio of the focal length of the film to the focal length of the objective lens system is 1.231.
[0015] A further technical solution is: the distance between the third lens and the film is 89 mm.
[0016] Compared with the prior art, the utility model has the following beneficial effects: the utility model only uses three lenses, namely, a first group of lenses with positive focal length, an aperture, a second group of lenses with negative focal length, a film with positive focal length, and an imaging surface, which are coaxially arranged. This achieves a balance between the requirements of imaging brightness, cost, image quality, and resolution. The utility model is easy to manufacture, has a small size, and a low cost, and can provide high-quality image display effects.
[0017] The utility model is further described below in conjunction with the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0019] Figure 1 A schematic diagram of a three-piece LCD projection lens provided by an embodiment of the utility model;
[0020] Figure 2 The spatial frequency MTF diagram provided by the embodiment of the utility model;
[0021] Figure 3 A vertical axis chromatic aberration diagram provided by an embodiment of the utility model;
[0022] Figure 4 A field curvature evaluation diagram provided for an embodiment of the utility model;
[0023] Figure 5 A field curvature distortion diagram provided by an embodiment of the utility model;
[0024] Description of the symbols in the figure:
[0025] 1. First group of lenses; 2. Aperture; 3. Second group of lenses; 4. Film; 5. Imaging surface; G1. First lens; G2. Second lens; G3. Third lens. DETAILED DESCRIPTION
[0026] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.
[0027] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.
[0028] It should also be understood that the terms used in this utility model specification are only for the purpose of describing specific embodiments and are not intended to limit the utility model. As used in this utility model specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.
[0029] It should be further understood that the term “and / or” used in the present specification and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.
[0030] See also Figure 1 , Figure 1 A schematic diagram of a three-piece LCD projection lens provided in an embodiment of the utility model can be used in projection scenes. The lens has only three lenses, reasonably balances imaging brightness, cost, image quality and resolution, and has a series of advantages such as easy manufacturing, small size, low cost and high imaging quality.
[0031] See also Figure 1 A three-piece LCD projection lens comprises: a coaxially arranged first group lens 1 with positive focal length, an aperture 2, a second group lens 3 with negative focal length, a film 4 with positive focal length, and an imaging surface 5.
[0032] In this embodiment, the film 4 is made of plastic, and the lenses of other lenses are all made of glass.
[0033] In one embodiment, the first lens group 1 is located before the aperture 2 , and the first lens group 1 includes a first lens G1 with positive refractive power.
[0034] In one embodiment, the second lens group 3 is located behind the aperture 2. The second lens group 3 includes a second lens G2 with negative refractive power and a third lens G3 with positive refractive power. The second lens G2 is located between the aperture 2 and the third lens G3. The third lens G3 is located between the second lens G2 and the film 4.
[0035] In one embodiment, the first lens G1 , the second lens G2 , and the third lens G3 are spherical lenses respectively.
[0036] In one embodiment, the ratio of the focal length of the first lens group 1 to the focal length of the objective lens system is 0.478.
[0037] In one embodiment, the ratio of the focal length of the second lens group 3 to the focal length of the objective lens system is -1.087.
[0038] In one embodiment, the ratio of the focal length of the second lens G2 to the focal length of the second lens group 3 is 3.787.
[0039] In one embodiment, the ratio of the focal length of the third lens G3 to the focal length of the second lens group 3 is -8.492.
[0040] In one embodiment, the ratio of the focal length of the film 4 to the focal length of the objective lens system is 1.231.
[0041] The objective lens system refers to a system composed of three LCD projection lenses. The specific parameters of the objective lens system are shown in Table 1.
[0042] Table 1. Specific parameters of objective lens system
[0043]
[0044]
[0045] Among them, the focal length of film 4 f4 is 130mm.
[0046] The projection lens obtained according to the specific parameters of each lens mentioned above is as follows: Figure 1 shown.
[0047] In addition, the spatial frequency MTF diagram of the above three-piece LCD projection lens is as follows: Figure 2As shown, the MTF (Modulation Transfer Function) index is the most accurate and scientific evaluation standard for lenses at present. The ordinate represents contrast. The closer it is to 1, the better the lens imaging. The abscissa represents resolution, in units of line pairs per millimeter. The image source pixel size used in the embodiment of the present application is 46.1um, and the corresponding half Nyquist frequency is 5.4 line pairs per millimeter. Projection lenses generally require that the MTF value of each field of view is at least 0.3 at the design resolution. The MTF values of each field of view in this embodiment at half the Nyquist frequency are all above 0.3.
[0048] Please refer to 3. The ordinate is the image height field value, and the abscissa is the numerical value, in micrometers. The figure takes the dominant wavelength as the reference, and plots the color difference values of each field of view between blue light, red light and green light (dominant wavelength). The projection lens generally requires the color difference value to be within the size of an image source pixel. The axial chromatic aberration of this embodiment is controlled within 11.5um, which is less than 0.25 pixel size (pixel size 46.1um).
[0049] See also Figure 4 and Figure 5 , the ordinate represents the field of view angle of the lens. The abscissa of the field curvature graph represents the magnitude of the field curvature value, and the abscissa of the distortion graph represents the amount of distortion. Distortion is a very important indicator of a projection lens, and generally needs to be controlled within 3%, while TV distortion is required to be controlled within 1%; the system distortion of this embodiment is within 0.3%, and the TV distortion is also within 0.2%, and the system distortion properties are excellent.
[0050] In one embodiment, the distance between the third lens G3 and the film 4 is 89 mm, which provides enough space for adding a plane reflector to fold the light path, thereby reducing the size of the projector.
[0051] In one embodiment, the projection ratio of the three-chip LCD projection lens reaches 1.2, which is suitable for most daily viewing needs, and has a short total length, meeting the needs of micro-projection equipment.
[0052] In one embodiment, the effective focal length of the three-piece LCD projection lens is 105.7 mm, and F / NO. is 2.8.
[0053] In one embodiment, the three-piece LCD projection lens uses a 4.0-inch LCD screen with a resolution of 1920*1080.
[0054] In one embodiment, the three-piece LCD projection lens uses a film 4, which can effectively converge the main light angle of the lens.
[0055] In one embodiment, the relative illumination of the full field of view of the three-piece LCD projection lens is higher than 70%; the distortion can reach within 0.3%, the TV distortion is within 0.2%, and the distortion correction is very excellent.
[0056] The lenses of the above-mentioned three-piece LCD projection lens are all glass spherical lenses. Only 3 lenses are used, and the materials used are all low-cost optical lens materials, which greatly reduce the lens cost and assembly difficulty; the chromatic aberration correction is excellent, the axial chromatic aberration is less than 11.5um, which is less than 0.25 pixel points; the resolution reaches 1920*1080, which can bring a good viewing experience.
[0057] In one embodiment, the three-piece LCD projection lens satisfies the following conditional formula: 1.4 < EPND / IH < 1.6, where EPND represents the clear aperture of the optical lens, and IH represents the actual semi-image height of the optical lens.
[0058] When 1.4 < EPND / IH < 1.6, a reasonable balance between the light transmission of the lens and the size of the imaging surface 5 can be achieved.
[0059] In one embodiment, the optical lens satisfies the following conditional formula: 20.5 < TL*f / IH 2 < 22.3; where TL represents the overall optical length of the optical lens, f represents the effective focal length of the optical lens, and IH represents the actual semi-image height of the optical lens.
[0060] When 20.5 < TL*f / IH 2 < 22.3, the relationship between the overall length of the lens and the resolution ability can be reasonably balanced. When the value of TL / f / IH 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; when the value of TL / f / IH exceeds the lower limit, due to the excessive optical power of each lens, it is difficult to correct the lens aberration, and the resolution ability decreases significantly.
[0061] In one embodiment, the optical lens satisfies the following conditional formula: 30.0mm < IH / tanθ < 32.1mm; where IH represents the actual semi-image height of the optical lens, and θ represents the semi-field angle of the optical lens. When 30.0mm < IH / tanθ < 32.1m, the distortion of the optical lens can be reasonably limited, and the difficulty of distortion correction can be reduced. 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.
[0062] In an embodiment, the optical lens satisfies the following conditional formula: CRA < 3°; where CRA represents the principal ray incident angle of the optical lens on the imaging surface 5. When CRA < 3° is satisfied, it can better match the LCD liquid crystal display screen and achieve a good projection effect.
[0063] In an embodiment, the optical lens satisfies the following conditional formula: 1.8 < fG3 / fG1 < 2.1; where fG3 represents the focal length of the G3 lens and fG1 represents the focal length of the G1 lens. In a three-piece LCD projection lens, the number of lenses is small. In order to obtain a better imaging effect, the optical power adopts a positive-negative-positive combination method, and the focal lengths of the front and rear positive optical power lenses are close, which can enhance the system symmetry and is beneficial to image quality optimization. When 1.8 < fG3 / fG1 < 2.1 is satisfied, a better image quality can be obtained while meeting the system focal length.
[0064] The above-mentioned optical lens refers to a three-piece LCD projection lens. This lens has a series of advantages such as high imaging quality, few lens elements, small distortion, reasonable tolerances, and low cost.
[0065] For a three-piece LCD projection lens described above, by arranging a first group of lenses 1 with positive optical power, a diaphragm 2, a second group of lenses 3 with negative optical power, a film 4 with positive optical power, and an imaging surface 5 coaxially, only three lenses are used to meet the requirements in terms of balanced imaging brightness, cost, image quality, and resolution, which is easy to manufacture, has a small volume, and low cost, and can simultaneously provide a high-quality image display effect.
[0066] As described above, the above is only the specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of various equivalent modifications or substitutions, and these modifications or substitutions should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims
1. A three-piece LCD projection lens, characterized in that: include: A first lens group with positive focal length, an aperture, a second lens group with negative focal length, a film with positive focal length, and an imaging surface are coaxially arranged.
2. The three-piece LCD projection lens according to claim 1, characterized in that: The first lens group includes a first lens with positive refractive power.
3. The three-piece LCD projection lens according to claim 2, characterized in that: The second lens group includes a second lens with negative optical power and a third lens with positive optical power; the second lens is located between the aperture and the third lens; and the third lens is located between the second lens and the film.
4. The three-piece LCD projection lens according to claim 3, characterized in that: The first lens, the second lens and the third lens are spherical lenses respectively.
5. The three-piece LCD projection lens according to claim 4, characterized in that: The ratio of the focal length of the first lens group to the focal length of the objective lens system is 0.
478.
6. The three-piece LCD projection lens according to claim 4, characterized in that: The ratio of the focal length of the second lens group to the focal length of the objective lens system is -1.
087.
7. The three-piece LCD projection lens according to claim 4, characterized in that: The ratio of the focal length of the second lens to the focal length of the second lens group is 3.
787.
8. The three-piece LCD projection lens according to claim 4, characterized in that: The ratio of the focal length of the third lens to the focal length of the second lens group is -8.
492.
9. The three-piece LCD projection lens according to claim 4, characterized in that: The ratio of the focal length of the film to the focal length of the objective lens system is 1.
231.
10. The three-piece LCD projection lens according to claim 4, characterized in that: The distance between the third lens and the film is 89 mm.