High-uniformity high-definition projection lens
By designing a specific projection lens structure, including multiple sets of lenses and spectroscopic prisms, the long-back working distance and distortion problems of existing projection lenses when matching DLP technology is solved, short-distance projection and large-focus depth characteristics are achieved, and optimized in multiple aspects.
Patent Information
- Application Number
- CN202420331537.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-02-22
- Publication Date
- 2025-02-28
- Estimated Expiration
- 2034-02-22
AI Technical Summary
When matching DLP technology, existing projection lenses need to retain a long rear working distance, resulting in increased lens length and difficulty in controlling out-of-axis aberration, and increased field angle leads to distortion problems.
A high uniform high-definition projection lens is designed, which includes a first group of lenses, a system aperture, a second group of lenses, a spectroscopic prism and a protective glass along the optical axis. Through specific lens combinations and structural designs, short-distance projection and large-focus depth characteristics are achieved.
It realizes short-distance projection matching 0.65inch DMD, has large focus depth characteristics, and can achieve excellent image quality with working distance of 2m, and achieves balance in small size, cost, image quality and resolution, with the advantages of ease of manufacturing and low cost.
Smart Images
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Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of optical lenses, in particular to a high-uniformity high-definition projection lens. Background Art
[0002] The projection lens is the core component of the projection equipment. After the light passes through the reflective or projective light modulation device, it is projected onto the projection screen through the projection lens to form an image.
[0003] DLP technology is a digital image chip developed by Texas Instruments, USA. Its working surface is composed of a large number of micro-mirror arrays, and the reversal angle of each lens can be controlled individually. The reflection angles of different models of DMD lenses are 12° and 14.5°. DLP technology has developed rapidly in the projection industry and has occupied most of the market in the home and commercial projection industry. DLP projection lighting systems are widely used. TIR or RTIR prisms are used to achieve effective lighting. Therefore, when matching with it, the projection lens needs to retain a longer back working distance, which greatly increases the difficulty of controlling the lens length and off-axis aberration. The general response is to add lenses, but generally more than ten lenses, which makes the lens complicated. In addition, since the projector uses 100% compensation to ensure ease of use, this will increase the field of view angle, resulting in obvious distortion. Therefore, it is very necessary to design a high-uniformity high-definition projection lens. Utility Model Content
[0004] The purpose of the utility model is to provide a high-uniformity high-definition projection lens that can match a 0.65-inch DMD, can achieve short-distance projection, and has a large focal depth characteristic. It can present excellent image quality at a working distance of 2m, can reasonably balance small size, cost, image quality and resolution, and fully considers the actual application scenarios. It has a series of advantages such as easy manufacturing, reasonable tolerance, low cost and high imaging quality, and has high practical application value.
[0005] To achieve the above purpose, the utility model provides the following solutions:
[0006] A high-uniformity high-definition projection lens, which includes, along the optical axis from the object plane to the imaging plane, a first group of lenses, a system aperture, a second group of lenses, a beam splitter prism and a protective glass;
[0007] The first lens group includes a first lens GM1, a second lens G2, a third lens G3 and a fourth lens G4 in sequence from the object plane to the imaging plane along the optical axis;
[0008] The second lens group includes a fifth lens G5, a sixth lens G6, a seventh lens G7, and an eighth lens GM8 in sequence from the object plane to the imaging plane along the optical axis;
[0009] The first lens GM1 is a glass aspherical lens with negative power, the second lens G2 is a glass spherical lens with negative power, and the third lens G3 and the fourth lens G4 are both glass spherical lenses with positive power;
[0010] The fifth lens G5 and the sixth lens G6 are glass spherical doublet lenses with negative power, the seventh lens G7 is a glass spherical lens with positive power, and the eighth lens GM8 is a glass aspherical lens with positive power;
[0011] The ratio of the focal length f1 of the first group of lenses to the system focal length f of the high uniformity high definition projection lens is 2.732;
[0012] The ratio of the focal length f2 of the second group of lenses to the system focal length f of the high uniformity high definition projection lens is 2.411;
[0013] The focal lengths of the fifth lens G5 and the sixth lens G6 are f G 5G The ratio of 6 to the system focal length f of the high uniformity HD projection lens is -4.701;
[0014] The focal length f of the first lens GM1 is GM1 The ratio to the focal length f of a high uniformity HD projection lens is -2.728;
[0015] The focal length f of the eighth lens GM8 GM8 The ratio to the focal length f of a high uniformity HD projection lens is 3.104.
[0016] Optionally, the imaging surface is a DMD imaging surface.
[0017] According to the specific embodiments provided by the utility model, the utility model discloses the following technical effects: the high-uniformity high-definition projection lens provided by the utility model includes: a first group lens, a system aperture, a second group lens, a dichroic prism and a protective glass in sequence from the object plane to the imaging plane along the optical axis; the first group lens includes a first lens GM1, a second lens G2, a third lens G3 and a fourth lens G4 in sequence from the object plane to the imaging plane along the optical axis; the second group lens includes a fifth lens G5, a sixth lens G6, a seventh lens G7 and an eighth lens GM8 in sequence from the object plane to the imaging plane along the optical axis; it can match 0.65-inch DMD, can realize short-distance projection, and has a large depth of focus characteristic, can present excellent image quality at a working distance of 2m, can reasonably balance small size, cost, image quality and resolution, and fully considers the actual application scenarios, has a series of advantages such as easy manufacturing, reasonable tolerance, low cost and high imaging quality, and has high practical application value. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] 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 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.
[0019] Figure 1 This is a schematic diagram of the structure of a high-uniformity high-definition projection lens according to an embodiment of the utility model;
[0020] Figure 2 This is a schematic diagram of the MTF of a high-uniformity HD projection lens;
[0021] Figure 3 This is a schematic diagram of the point array of a high-uniformity high-definition projection lens;
[0022] Figure 4 This is a schematic diagram of the field curvature and distortion evaluation of a high-uniformity HD projection lens;
[0023] Figure 5 This is a schematic diagram of vertical axis chromatic aberration;
[0024] Figure 6 Schematic diagram of relative illumination of high-uniformity HD projection lens.
[0025] Reference numerals: 1. first group of lenses; 2. system aperture; 3. second group of lenses; 4. beam splitter prism; 5. protective glass; 6. DMD imaging surface. 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 only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in 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] The purpose of the utility model is to provide a high-uniformity high-definition projection lens that can match a 0.65-inch DMD, can achieve short-distance projection, and has a large focal depth characteristic. It can present excellent image quality at a working distance of 2m, can reasonably balance small size, cost, image quality and resolution, and fully considers the actual application scenarios. It has a series of advantages such as easy manufacturing, reasonable tolerance, low cost and high imaging quality, and has high practical application value.
[0028] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.
[0029] The high-uniformity high-definition projection lens provided by the utility model has a total length of less than 150 mm (including a prism light splitter), and a thickness compressed to within 13 mm.
[0030] like Figure 1 As shown, the high uniformity high definition projection lens provided by the embodiment of the utility model comprises, in order from the object plane to the imaging plane along the optical axis: a first group of lenses, a system aperture, a second group of lenses, a beam splitter prism and a protective glass;
[0031] The first lens group includes a first lens GM1, a second lens G2, a third lens G3 and a fourth lens G4 in sequence from the object plane to the imaging plane along the optical axis;
[0032] The second lens group includes a fifth lens G5, a sixth lens G6, a seventh lens G7, and an eighth lens GM8 in sequence from the object plane to the imaging plane along the optical axis;
[0033] The first lens GM1 is a glass aspherical lens with negative power, the second lens G2 is a glass spherical lens with negative power, and the third lens G3 and the fourth lens G4 are both glass spherical lenses with positive power;
[0034] The fifth lens G5 and the sixth lens G6 are glass spherical doublet lenses with negative power, the seventh lens G7 is a glass spherical lens with positive power, and the eighth lens GM8 is a glass aspherical lens with positive power;
[0035] The ratio of the focal length f1 of the first group of lenses to the system focal length f of the high uniformity high definition projection lens is 2.732;
[0036] The ratio of the focal length f2 of the second group of lenses to the system focal length f of the high uniformity high definition projection lens is 2.411;
[0037] The focal lengths of the fifth lens G5 and the sixth lens G6 are f G 5G The ratio of 6 to the system focal length f of the high uniformity HD projection lens is -4.701;
[0038] The focal length f of the first lens GM1 is GM1 The ratio to the focal length f of a high uniformity HD projection lens is -2.728;
[0039] The focal length f of the eighth lens GM8 GM8 The ratio to the focal length f of a high uniformity HD projection lens is 3.104.
[0040] The imaging surface is the DMD imaging surface.
[0041] The specific parameters of the high uniformity HD projection lens are shown in Table 1.
[0042] Table 1 Specific parameters
[0043]
[0044]
[0045] The order coefficients of the first lens GM1 and the eighth lens GM8 are shown in Table 2;
[0046] Table 2 The coefficients of the first lens GM1 and the eighth lens GM8
[0047]
[0048] The projection lens obtained according to the specific parameters of each lens mentioned above is as follows: Figure 1 The objective lens system 2DLayout is shown in the figure;
[0049] The MTF (Modulation Transfer Function) index is the most accurate and scientific evaluation standard for lenses. The vertical axis represents contrast. The closer it is to 1, the better the lens imaging. The horizontal axis represents resolution, in units of line pairs per millimeter. The image source pixel size used in the embodiment of the present application is 10.8μm, and the corresponding design resolution is 47 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. Figure 2 As shown, the MTF values of each field of view in the embodiment of the present application are all above 0.7, with extremely excellent imaging quality.
[0050] Figure 3 It is a point diagram of each field of view of the lens. After many light rays emitted from one point pass through the optical system, due to aberration, their intersection with the image plane is no longer concentrated at the same point, but a diffuse pattern is formed that is scattered in a certain range. The smaller the spot radius of each field of view, the better the imaging quality it represents. Generally, the full field of view RMS is less than the pixel size (10.8um), which is an excellent level. The full field of view RMS of the embodiment of the present application is less than 10.8um, which is an excellent level.
[0051] Figure 4 The figure on the right is the field curvature evaluation diagram, and the figure on the right is the distortion evaluation diagram. The ordinate represents the field angle of the lens. The abscissa of the field curvature diagram represents the magnitude of the field curvature value, and the abscissa of the distortion diagram represents the amount of distortion. Distortion is a very important indicator of a projection lens; the system distortion of the embodiment of the present application is within 0.5%, and the system distortion is excellent.
[0052] Figure 5The vertical axis chromatic aberration diagram of the lens, the ordinate is the image height field value, the abscissa is the numerical value, the unit is micrometer. The figure takes the main wavelength as the reference, and plots the color difference values of each field of view between blue light, red light and green light (main wavelength). The projection lens generally requires the color difference value to be within the size of an image source pixel. In the embodiment of the present application, it is less than 0.25 pixel size (pixel size 10.8μm).
[0053] Figure 6 is the relative illumination diagram of the lens. Relative illumination refers to the ratio of the illumination at different coordinate points on the image plane to the illumination at the center point. The ordinate represents the normalized illumination value, and the abscissa represents the field of view angle of the lens. Under the same conditions, the smooth transition of the relative illumination curve of each field of view represents uniform illumination within the projection frame. The closer the relative illumination value of each field of view is to 1, the higher the final projection brightness. The relative illumination of all fields of view in the embodiment of the present application is higher than 95%.
[0054] From the implementation case, it can be seen that when the working distance is set to 2000mm, the MTF (Modulation Transfer Function) of the lens at low, medium and high frequencies are all very good, which can be analyzed to have a high resolution effect.
[0055] It can be seen from the case 2D layout that the length of the entire system structure is not large and is controlled within 150mm.
[0056] The optical distortion of the lens is less than 0.5 percent.
[0057] The lens uses a 0.65-inch image source.
[0058] The relative illumination of the lens is very high, which is beneficial to improving the uniformity of the optical machine.
[0059] The lens adopts a wavelength FdC three-color lamp source as a light source, and the selected lens material has a high transmittance to light of visible light wavelengths.
[0060] The lenses used have four pieces of glass made of the same material, which reduces the types of glass used;
[0061] In an embodiment, the optical lens satisfies the following conditional formula:
[0062] CRA<3°
[0063] Wherein, CRA represents the incident angle of the principal ray of the optical lens on the imaging surface, which can well match the imaging chip to achieve a good projection effect.
[0064] Implementation case: Full field of view CRA < 0.4°.
[0065] This application is 100% biased, which makes it easy to use the projection of this lens and can be placed directly on the desktop for projection.
[0066] The high uniformity high-definition projection lens provided by the utility model comprises, in order from the object plane to the imaging plane along the optical axis: a first group lens, a system aperture, a second group lens, a beam splitter prism and a protective glass, the first group lens comprises in order from the object plane to the imaging plane along the optical axis a first lens GM1, a second lens G2, a third lens G3 and a fourth lens G4, the second group lens comprises in order from the object plane to the imaging plane along the optical axis a fifth lens G5, a sixth lens G6, a seventh lens G7 and an eighth lens GM8; the utility model can match a 0.65-inch DMD, can realize short-distance projection, and has a large focal depth characteristic, can present excellent image quality at a working distance of 2m, can reasonably balance small size, cost, image quality and resolution, and fully considers actual application scenarios, has a series of advantages such as easy manufacturing, reasonable tolerance, low cost and high imaging quality, and has high practical application value.
[0067] This article uses specific examples to illustrate the principles and implementation methods of the utility model. The above examples are only used to help understand the method and core ideas of the utility model. At the same time, for those skilled in the art, according to the ideas of the utility model, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the utility model.
Claims
1. A high uniformity high definition projection lens, characterized in that: The optical axis includes, from the object plane to the imaging plane, a first lens group, a system aperture, a second lens group, a beam splitter prism and a protective glass; The first lens group includes a first lens GM1, a second lens G2, a third lens G3 and a fourth lens G4 in sequence from the object plane to the imaging plane along the optical axis; The second lens group includes a fifth lens G5, a sixth lens G6, a seventh lens G7, and an eighth lens GM8 in sequence from the object plane to the imaging plane along the optical axis; The first lens GM1 is a glass aspherical lens with negative power, the second lens G2 is a glass spherical lens with negative power, and the third lens G3 and the fourth lens G4 are both glass spherical lenses with positive power; The fifth lens G5 and the sixth lens G6 are glass spherical doublet lenses with negative power, the seventh lens G7 is a glass spherical lens with positive power, and the eighth lens GM8 is a glass aspherical lens with positive power; The ratio of the focal length f1 of the first group of lenses to the system focal length f of the high uniformity high definition projection lens is 2.732; The ratio of the focal length f2 of the second group of lenses to the system focal length f of the high uniformity high definition projection lens is 2.411; The focal lengths of the fifth lens G5 and the sixth lens G6 are f G5G6 The ratio to the system focal length f of the high uniformity HD projection lens is -4.701; The focal length f of the first lens GM1 is GM1 The ratio to the focal length f of a high uniformity HD projection lens is -2.728; The focal length f of the eighth lens GM8 GM8 The ratio to the focal length f of a high uniformity HD projection lens is 3.
104.
2. The high uniformity high definition projection lens according to claim 1, characterized in that: The imaging surface is the DMD imaging surface.