Projection lens

Abstract

The invention provides a projection lens. The projection lens sequentially comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a Fresnel lens and an LCD chip from a first side to a second side along an optical axis, and the fifth lens has positive diopter; the total optical length TTL of the projection lens and the effective focal length EFL of the projection lens meet the condition that TTL / EFL is larger than or equal to 2.80. The projection lens solves the problem that high resolution and miniaturization of a projection lens in the prior art are difficult to consider at the same time.

Description

Technical Field

[0001] The present invention relates to the technical field of optical imaging devices, and more particularly, to a projection lens. Background Art

[0002] As projectors are increasingly widely used in various fields, the design of the projection lens, which is the core part, has been continuously improved and optimized. Although LCD display technology is a traditional display technology, it has still been continuously breaking through with the development of the times. Compared with LED projection products, LCD projection display products have the advantages of high picture contrast, clear imaging, and high color gamut. These remarkable advantages have gradually made LCD projection display technology become another mainstream development direction in the market. Traditional LCDs are small-sized display chips, which makes the volume of the projection lens relatively small, and the pixel resolution is usually 1080P, with relatively low resolution. However, using a high-resolution chip to meet the projection image quality will increase the volume of the projection lens, which is not conducive to miniaturization.

[0003] That is to say, there is a problem in the projection lens in the prior art that it is difficult to simultaneously achieve high resolution and miniaturization. Summary of the Invention

[0004] The main object of the present invention is to provide a projection lens to solve the problem in the projection lens in the prior art that it is difficult to simultaneously achieve high resolution and miniaturization.

[0005] To achieve the above object, the present invention provides a projection lens, which sequentially includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a Fresnel lens, and an LCD chip along the optical axis from the first side to the second side. Among them, the fifth lens has a positive refractive power; the total optical length TTL of the projection lens and the effective focal length EFL of the projection lens satisfy: TTL / EFL≥2.80.

[0006] Further, the effective focal length EFL of the projection lens and the back focal length BFL of the projection lens satisfy: BFL / EFL≥1.0; and / or the total optical length TTL of the projection lens satisfies: TTL≤200mm.

[0007] Further, the effective focal length EFL of the projection lens satisfies: 120mm≤EFL≤140mm; and / or the relative aperture number FNO of the projection lens satisfies: 2.0≤FNO≤3.5.

[0008] Further, the telecentric angle TA of the projection lens satisfies: TA≤3.0°; and / or the field of view FOV of the projection lens satisfies: FOV≥66°.

[0009] Furthermore, the ratio TR between the projection distance of the projection lens and the picture width satisfies: 1.1 ≤ TR ≤ 1.3; and / or the size of the LCD chip is less than 5.6 inches.

[0010] Furthermore, the projection lens further includes a diaphragm, and the diaphragm is disposed between the third lens and the fourth lens, between the second lens and the third lens, or between the fourth lens and the fifth lens.

[0011] Furthermore, there is at least one doublet lens between the diaphragm and the LCD chip; and / or at least one meniscus aspherical lens is disposed on the first side of the diaphragm, and at least one set of lenses with positive and negative refractive powers is disposed on the second side of the diaphragm.

[0012] Furthermore, at least one plastic lens is disposed on the first side of the diaphragm, and / or at least one set of lenses with positive and negative refractive powers is disposed on the first side of the diaphragm.

[0013] Furthermore, the lenses between the diaphragm and the LCD chip form a second group, and the diaphragm is located at the focal position of the second group.

[0014] Furthermore, the resolution of the LCD chip = 1 / (2*X) * 1000; where X is the pixel size of the LCD chip, and X is greater than or equal to 30 um.

[0015] Applying the technical solution of the present invention, the projection lens sequentially includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a Fresnel lens, and an LCD chip along the optical axis from the first side to the second side, wherein the fifth lens has a positive refractive power; the total optical length TTL of the projection lens and the effective focal length EFL of the projection lens satisfy: TTL / EFL ≥ 2.80.

[0016] By adopting an LCD chip, planning that the fifth lens has a positive refractive power, and at the same time restricting the ratio of the total optical length TTL of the projection lens to the effective focal length EFL of the projection lens to be in the range of more than 2.80, it is beneficial to ensure that the total optical length of the projection lens is reasonably restricted on the premise of meeting high resolution, which is beneficial to compressing the overall length, thereby achieving miniaturization. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The specification drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0018] Figure 1 The structural schematic diagram of the projection lens of the first embodiment of the present invention is shown;

[0019] Figures 2 to 4 Are respectively shown Figure 1Field curvature diagram, distortion diagram, and MTF curve diagram of the projection lens in

[0020] Figure 5 Fig. shows a schematic structural diagram of the projection lens according to the second embodiment of the present invention;

[0021] Figure 6 and Figure 7 respectively show Figure 5 the field curvature diagram and distortion diagram of the projection lens in

[0022] Figure 8 Fig. shows a schematic structural diagram of the projection lens according to the third embodiment of the present invention;

[0023] Figure 9 and Figure 10 respectively show Figure 8 the field curvature diagram and distortion diagram of the projection lens in

[0024] Figure 11 Fig. shows a schematic structural diagram of the projection lens according to the fourth embodiment of the present invention;

[0025] Figure 12 and Figure 13 respectively show Figure 11 the field curvature diagram and distortion diagram of the projection lens in

[0026] Among them, the above-mentioned drawings include the following reference numerals:

[0027] L1, the first lens; L2, the second lens; L3, the third lens; L4, the fourth lens; L5, the fifth lens; L6, the sixth lens; L7, the seventh lens; STOP, the aperture; 10, the Fresnel lens; 20, the LCD chip. Detailed Embodiments

[0028] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the drawings and in combination with the embodiments.

[0029] It should be pointed out that, unless otherwise specified, all technical and scientific terms used in the present application have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs.

[0030] In the present invention, unless otherwise stated, the orientation terms such as "upper, lower, top, bottom" are usually in the direction shown in the drawings, or in the vertical, perpendicular or gravitational direction of the component itself; similarly, for ease of understanding and description, "inner, outer" refer to the inner and outer of the contour of each component itself, but the above orientation terms do not limit the present invention.

[0031] It should be noted that in this specification, the expressions such as first, second, third, etc. are only used to distinguish one feature from another, and do not represent any limitation on the features.

[0032] In this text, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the position of the convex surface is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the position of the concave surface is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens close to the first side becomes the first side surface of the lens, and the surface of each lens close to the second side is called the second side surface of the lens. The judgment of the surface shape in the paraxial region can be based on the judgment method of those with ordinary knowledge in this field, and the positive and negative of the R value (R refers to the radius of curvature in the paraxial region, usually the R value on the lens database (lens data) in optical software) is used to judge the convexity and concavity. For the first side surface, when the R value is positive, it is judged to be convex, and when the R value is negative, it is judged to be concave; for the second side surface, when the R value is positive, it is judged to be concave, and when the R value is negative, it is judged to be convex.

[0033] In this application, the left side of the projection lens is the first side, and the right side is the second side. In the specific embodiment of this application, the first side of the projection lens is the magnification side, and the second side is the reduction side. When projecting, the light from the LCD chip 20 on the reduction side can be imaged on the magnification side.

[0034] In order to solve the problem that it is difficult to simultaneously achieve high resolution and miniaturization in the existing projection lens, the present invention provides a projection lens.

[0035] As Figures 1 to 13 shown, the projection lens sequentially includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a Fresnel lens 10, and an LCD chip 20 along the optical axis from the first side to the second side. Among them, the fifth lens L5 has a positive refractive power; the total optical length TTL of the projection lens and the effective focal length EFL of the projection lens satisfy: TTL / EFL≥2.80.

[0036] By using the LCD chip 20, planning that the fifth lens L5 has a positive refractive power, and at the same time restricting the ratio of the total optical length TTL of the projection lens to the effective focal length EFL of the projection lens to be in the range of more than 2.80, it is beneficial to ensure that the total optical length of the projection lens is reasonably restricted on the premise of meeting high resolution, which is beneficial to compressing the overall length, thereby achieving miniaturization.

[0037] Specifically, the effective focal length EFL of the projection lens satisfies: 120 mm ≤ EFL ≤ 140 mm. By reasonably restricting the effective focal length of the projection lens within the range of 120 mm to 140 mm, it is beneficial to ensure the stability of the focal length of the projection lens, making the projection lens of the present application a fixed-focus projection lens.

[0038] Specifically, the total optical length TTL of the projection lens satisfies: TTL ≤ 200 mm. By reasonably restricting the total optical length TTL of the projection lens within the range of 200 mm, it is beneficial to ensure the miniaturization feature.

[0039] Specifically, between the effective focal length EFL of the projection lens and the back focal length BFL of the projection lens, it satisfies: BFL / EFL ≥ 1.0. By reasonably restricting this conditional formula, it is beneficial to ensure the long back focal length feature of the projection lens.

[0040] Specifically, the relative aperture FNO of the projection lens satisfies: 2.0 ≤ FNO ≤ 3.5. Preferably, 2.0 ≤ FNO ≤ 3.0. By reasonably restricting the aperture number of the projection lens, it is beneficial to ensure the large aperture feature and beneficial to increase the light transmission amount. FNO = the effective focal length of the projection lens / the aperture diameter. When the effective focal length of the projection lens remains unchanged, the larger the aperture diameter, the larger the light transmission port, and the more light rays can be received, so the higher the brightness.

[0041] Specifically, the telecentric angle TA of the projection lens satisfies: TA ≤ 3.0°; the field of view FOV of the projection lens satisfies: FOV ≥ 66°; the ratio TR between the projection distance and the picture width of the projection lens satisfies: 1.1 ≤ TR ≤ 1.3. The size of the LCD chip 20 is less than 5.6 inches. In a specific embodiment of the present application, the size of the LCD chip 20 is 5 inches. Cooperating with the 5-inch LCD chip 20, a 228.6 cm (90-inch) picture can be projected at a working distance of 2390 mm, and it supports a 5-inch LCD one-way longitudinal offset -40% to offset +40% adjustment change; ensure that the projection lens has good MTF performance, small distortion, simple structure, and good imaging quality at the spatial limit frequency of 17 lp / mm in the visible light band of 450 nm to 630 nm.

[0042] In the present application, the projection lens is a projection lens with a large aperture FNO of 2.8. Under the condition of realizing efficient light transmission, the LCD chip 20 has a 4K resolution, and the resolution of the LCD chip 20 is calculated by the following formula:

[0043] The resolution of the LCD chip 20 = 1 / (2*X)*1000;

[0044] Among them, X is the pixel size of the LCD chip 20. In this application, X is greater than or equal to 30um, and preferably X is equal to 30um. In this way, on the premise of using a large-size and high-resolution LCD chip 20 for the projection lens of this application, the composition, diopter, surface shape, and various parameter relationships of the lens can be reasonably set, so that the projection lens of this application has the advantages of high brightness, low chromatic aberration, low distortion, large aperture, low cost, and high imaging quality. At the same time, it is ensured that the projection lens of this application has a large imaging clear range, and it is ensured that the outgoing image is offset upward during the projection work, so that the outgoing light beam is higher than the position of the projection lens, and the projection image will not be blocked by the projection lens.

[0045] In an alternative embodiment of this application, the projection lens is composed of six lenses with diopters from the first lens L1 to the sixth lens L6, and the sixth lens L6 has a positive diopter. The projection lens further includes a stop STOP, and the stop STOP is disposed between the second lens L2 and the third lens L3 or between the third lens L3 and the fourth lens L4. By reasonably setting the position of the stop STOP, it is beneficial to effectively converge the light rays entering the optical system.

[0046] In another alternative embodiment of this application, the projection lens further includes a seventh lens L7, and the seventh lens L7 is located between the sixth lens L6 and the Fresnel lens 10. The projection lens is composed of seven lenses with diopters from the first lens to the seventh lens. At this time, the first lens L1 has a negative diopter, the fourth lens L4 has a negative diopter, the sixth lens L6 has a positive diopter, and the fifth lens L5 has a negative diopter. The projection lens further includes a stop STOP, and the stop STOP is disposed between the third lens L3 and the fourth lens L4 or between the fourth lens L4 and the fifth lens L5. By reasonably setting the position of the stop STOP, it is beneficial to effectively converge the light rays entering the optical system.

[0047] Specifically, there is at least one doublet lens between the stop STOP and the LCD chip 20. By reasonably setting the doublet lens, it is beneficial to correct chromatic aberration. At least one meniscus aspherical lens is disposed on the first side of the stop STOP, and at least one set of lenses with positive and negative diopters is disposed on the second side of the stop STOP. Such a setting is beneficial to correcting the chromatic aberration of the projection lens and improving the final imaging quality.

[0048] Specifically, at least one plastic lens is disposed on the first side of the stop STOP. By setting the plastic lens, the effect of improving distortion can be achieved. In addition, at least one set of lenses with positive and negative diopters is disposed on the first side of the stop STOP, so as to relieve the situation of thermal defocus.

[0049] Specifically, multiple lenses between the aperture STOP and the LCD chip 20 form a second group, and the aperture STOP is located at the focal position of the second group, which is conducive to the precise control of the convergence position.

[0050] In an alternative embodiment of the present application, one or both of the first lens L1 and the second lens L2 are aspherical lenses. By setting the aspherical lens, it is beneficial to correct field curvature, compress distortion, and achieve high resolution. Of course, in an alternative embodiment of the present application, one of the fourth lens L4 and the fifth lens L5 can also be selected as an aspherical lens.

[0051] The following further describes examples of the specific surface shapes and parameters of the projection lens applicable to the above embodiments in conjunction with the drawings and specific examples.

[0052] Embodiment 1

[0053] As Figures 1 to 5 shown, the projection lens of Embodiment 1 is described.

[0054] As Figure 1 shown, it is a schematic structural diagram of the projection lens of Embodiment 1. The projection lens sequentially includes, along the optical axis from the first side to the second side: a first lens L1, a second lens L2, a third lens L3, an aperture STOP, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, a Fresnel lens 10, and an LCD chip 20.

[0055] In this embodiment, the first lens L1 has a negative refractive power. The first side of the first lens L1 is convex, and the second side is concave, so that the first lens L1 is a negative meniscus lens. The second lens L2 has a positive refractive power. The first side of the second lens L2 is convex, and the second side is convex, so that the second lens L2 is a positive biconvex lens. The third lens L3 has a negative refractive power. The first side of the third lens L3 is convex, and the second side is concave, so that the third lens L3 is a negative meniscus lens. The fourth lens L4 has a negative refractive power. The first side of the fourth lens L4 is concave, and the second side is concave, so that the fourth lens L4 is a negative biconcave lens. The fifth lens L5 has a positive refractive power. The first side of the fifth lens L5 is convex, and the second side is convex, so that the fifth lens L5 is a positive biconvex lens. The sixth lens L6 has a positive refractive power. The first side of the sixth lens L6 is flat, and the second side is convex, so that the sixth lens L6 is a positive plano-convex lens. Of course, the sixth lens L6 can also be a biconvex lens or a meniscus lens. The seventh lens L7 has a negative refractive power. The first side of the seventh lens L7 is concave, and the second side is concave, so that the seventh lens L7 is a negative biconcave lens.

[0056] In this embodiment, the radius of curvature of the first side surface of the first lens L1 is 50 mm to 80 mm, and the radius of curvature of the second side surface of the first lens L1 is 40 mm to 70 mm. The radius of curvature of the first side surface of the second lens L2 is 90 mm to 120 mm, and the radius of curvature of the second side surface of the second lens L2 is -500 mm to -150 mm. The radius of curvature of the first side surface of the third lens L3 is 150 mm to 200 mm, and the radius of curvature of the second side surface of the third lens L3 is 40 mm to 150 mm. The radius of curvature of the first side surface of the fourth lens L4 is -300 mm to -200 mm, and the radius of curvature of the second side surface of the fourth lens L4 is 80 mm to 500 mm. The radius of curvature of the first side surface of the fifth lens L5 is 80 mm to 500 mm, and the radius of curvature of the second side surface of the fifth lens L5 is -300 mm to -50 mm. The radius of curvature of the first side surface of the sixth lens L6 is -∞ mm to -250 mm or 250 mm to +∞ mm, and the radius of curvature of the second side surface of the sixth lens L6 is -100 mm to -40 mm. The radius of curvature of the first side surface of the seventh lens L7 is -100 mm to -40 mm, and the radius of curvature of the second side surface of the seventh lens L7 is 70 mm to 120 mm.

[0057] In this embodiment, both the first lens L1 and the second lens L2 are aspherical lenses, and the third lens L3 to the seventh lens L7 are all spherical lenses. The first lens L1 is set as an aspherical lens, which can effectively correct the system distortion and off-axis aberration, specifically astigmatism and sine difference. The second lens L2 is set as an aspherical lens, which can cooperate with the first lens L1, thereby can cooperate to correct astigmatism and sine difference, and can effectively solve the projection change caused by different temperatures and compensate the performance of thermal defocus. The reasonable combination of positive and negative refractive powers reduces the influence of temperature rise on the performance of the projection lens. At the same time, the use of aspherical lenses simplifies the number of lenses and the lens structure, and improves the optical performance parameters.

[0058] In this embodiment, the fourth lens L4 and the fifth lens L5 are cemented to form a doublet lens, and the sixth lens L6 and the seventh lens L7 are cemented to form a doublet lens. These two doublet lenses can cooperate with each other to correct the chromatic aberration problem brought by the excellent correction system. The fourth lens L4 and the fifth lens L5 adopt a combination of low refractive index and high Abbe number and double concave high refractive index and low Abbe number materials, which can perform achromatic aberration design to ensure a small chromatic aberration of the entire optical system. Similarly, the sixth lens L6 and the seventh lens L7 play the same role, and the last lens is a negative lens, which can better reduce the volume of the rear group. The seventh lens L7 cooperates with the Fresnel lens to reduce the aperture of the lens.

[0059] In this embodiment, the second side of the Fresnel lens 10 is an even aspherical surface. By optimizing the even aspherical surface, the telecentric angle of the light can be excellently corrected, making the system tend to be a telecentric system.

[0060] Table 1 below shows the basic structural parameter table of the projection lens in the first embodiment.

[0061] Table 1

[0062]

[0063]

[0064] In the first embodiment, both the first lens L1 and the second lens L2 are aspherical lenses. The surface shapes of the aspherical lenses can be defined by, but are not limited to, the following aspherical formula:

[0065]

[0066] Among them, the parameter c is the curvature corresponding to the radius, r is the radial height of the lens, k is the conic quadratic curve coefficient (Conic Constant), and α1 to α8 are the aspherical coefficients corresponding to the second to sixteenth orders respectively. When the k coefficient is less than -1, the surface curve of the lens is a hyperbola; when the k coefficient is equal to -1, the surface curve of the lens is a parabola; when the k coefficient is between -1 and 0, the surface curve of the lens is an ellipse; when the k coefficient is equal to 0, the surface curve of the lens is a circle; when the k coefficient is greater than 0, the surface curve of the lens is an oblate circle. Table 2 below shows the conic quadratic curve coefficient k and the aspherical coefficients α1 to α8 that can be used for the surfaces S1, S2, S3, and S4 of the aspherical lens in the first embodiment.

[0067] Table 2

[0068] K <![CDATA[α2]]> <![CDATA[α3]]> <![CDATA[α4]]> <![CDATA[α5]]> <![CDATA[α6]]> <![CDATA[α7]]> <![CDATA[α8]]> S1 0.00E+00 1.48E-08 -1.70E-09 5.30E-12 -9.86E-15 1.18E-17 -7.50E-21 2.25E-24 S2 0.00E+00 9.76E-07 -7.87E-09 4.60E-11 -1.51E-13 2.90E-16 -2.95E-19 1.28E-22 S3 0.00E+00 -8.57E-07 1.32E-09 -1.87E-11 3.63E-14 -2.78E-17 -2.52E-20 4.33E-23 S4 0.00E+00 5.73E-07 4.07E-09 -4.44E-11 1.47E-13 -2.83E-16 2.72E-19 -9.70E-23

[0069] In this embodiment, the physical resolution of the LCD chip 20 is 17 lp / mm.

[0070] In this embodiment, the projection lens further includes a driving motor. The first lens L1 to the seventh lens L7 form a lens group. The driving motor is used to drive the movement of the lens group on the optical axis to adjust the position of the lens group to meet the requirements of different picture sizes. In addition, this application is a shift projection lens that supports changes in the projection distance. When the optical axis of the lens is translated, the projection screen will move in the same direction. During the movement of the projection lens, the overall image remains clear and stable except for the movement of the screen.

[0071] As Figure 2 shown, the field curvature diagram of the projection lens in the first embodiment is shown. As Figure 3As shown, the distortion diagram of the projection lens of Embodiment 1 is shown. As Figure 4 shown, the MTF curve diagram of the projection lens of Embodiment 1 is shown. This embodiment provides a fixed-focus projection lens with an aperture number of 2.8, a distortion less than 0.6%, and BFL / EFL ≥ 1.0. This lens has a precise structure and the advantage of low cost. The above projection lens forms a 90-inch diagonal screen at the 2430 mm position. This application is based on the principle of optical imaging. Using optical design software, the curvature radius, material, thickness, air gap of each lens of the projection lens, and multiple aspherical lenses are designed, and repeated optical optimization design is carried out, which can achieve small aberration, high resolution, simple structure, ingenious design, high manufacturability, and is convenient for mass production.

[0072] Embodiment 2

[0073] As Figures 5 to 7 shown, the projection lens of Embodiment 2 is described. To simplify the content, in this embodiment and the following embodiments, the same description content as that of Embodiment 1 will be omitted.

[0074] As Figure 5 shown, it is a schematic structural diagram of the projection lens of Embodiment 2. The projection lens sequentially includes, along the optical axis, from the first side to the second side: a first lens L1, a second lens L2, a stop STOP, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a Fresnel lens 10, and an LCD chip 20.

[0075] In this embodiment, the first lens L1 has a positive refractive power. The first side of the first lens L1 is a convex surface, and the second side is a concave surface. The second lens L2 has a negative refractive power. The first side of the second lens L2 is a concave surface, and the second side is a concave surface. The third lens L3 has a positive refractive power. The first side of the third lens L3 is a convex surface, and the second side is a convex surface. The fourth lens L4 has a negative refractive power. The first side of the fourth lens L4 is a concave surface, and the second side is a concave surface. The fifth lens L5 has a positive refractive power. The first side of the fifth lens L5 is a convex surface, and the second side is a convex surface. The sixth lens L6 has a negative refractive power. The first side of the sixth lens L6 is a concave surface, and the second side is a concave surface. By reasonably setting the refractive power and surface type of the lens, it has the ability to correct chromatic aberration, but the correction ability of the influence of temperature on resolution is weak.

[0076] In this embodiment, both the first lens L1 and the second lens L2 are aspherical lenses. Reasonably setting the aspherical lens is beneficial to the correction of distortion and off-axis aberration.

[0077] In this embodiment, the effective focal length EFL of the projection lens is 138.0 mm, the relative aperture number FNO of the projection lens is 2.8, the back focal length BFL of the projection lens is 124.5 mm, and the field of view FOV of the projection lens is 54°.

[0078] Table 3 below shows the basic structural parameter table of the projection lens of Example 1.

[0079] Table 3

[0080] Type Surface Radius of Curvature (mm) Thickness (mm) Refractive Index Abbe Number L1 S1 46.71 7.34 1.49 57 S2 42.79 12.96 L2 S3 -146.32 5.29 1.58 30.4 S4 172.34 5.45 STOP S5 Infinity 1.00 L3 S6 147.66 12.80 1.79～1.84 42～50 S7 -73.32 2.75 L4 S8 -98.39 3.00 1.62～1.65 32～38 S9 199.86 2.84 L5 S10 3027.38 12.54 S11 -60.02 6.13 L6 S12 -236.33 3.00 1.70～1.75 50～55 S13 99.71 110.00 Fresnel Lens S14 Infinity 1.80 1.58 30.4 S15 -65.56 10.00 PANEL S16 Infinity -

[0081] Table 4 shows the polynomial coefficients applicable to each aspherical mirror surface in Example 2, wherein each aspherical surface type can be defined by formula (1) given in Example 1 above.

[0082] Table 4

[0083] K <![CDATA[α2]]> <![CDATA[α3]]> <![CDATA[α4]]> <![CDATA[α5]]> <![CDATA[α6]]> <![CDATA[α7]]> <![CDATA[α8]]> <![CDATA[α9]]> <![CDATA[α 10 > S1 0.00E+00 -4.81E-06 1.56E-08 -8.15E-11 2.21E-13 -3.83E-16 4.21E-19 -2.86E-22 1.09E-25 -1.80E-29 S2 0.00E+00 -1.07E-06 1.31E-08 -7.98E-11 2.50E-13 -5.00E-16 6.34E-19 -4.89E-22 2.10E-25 -3.83E-29

[0084] As Figure 6 shown, it shows the field curvature diagram of the projection lens of Example 2. As Figure 7 shown, it shows the distortion diagram of the projection lens of Example 2. From Figure 6 and Figure 7 it can be seen that the projection lens of this embodiment can achieve good imaging quality.

[0085] Example 3

[0086] As Figures 8 to 10 shown, it describes the projection lens of Example 3.

[0087] As Figure 8 shown, it is a schematic structural diagram of the projection lens of Example 3. The projection lens sequentially includes, along the optical axis from the first side to the second side: a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a diaphragm STOP, a fifth lens L5, a sixth lens L6, a seventh lens L7, a Fresnel lens 10, and an LCD chip 20.

[0088] In this embodiment, the first lens L1 has a positive refractive power. The first side surface of the first lens L1 is a convex surface, and the second side surface is a concave surface. The second lens L2 has a negative refractive power. The first side surface of the second lens L2 is a convex surface, and the second side surface is a concave surface. The third lens L3 has a positive refractive power. The first side surface of the third lens L3 is a convex surface, and the second side surface is a convex surface. The fourth lens L4 has a negative refractive power. The first side surface of the fourth lens L4 is a concave surface, and the second side surface is a concave surface. The fifth lens L5 has a positive refractive power. The first side surface of the fifth lens L5 is a concave surface, and the second side surface is a convex surface. The sixth lens L6 has a negative refractive power. The first side surface of the sixth lens L6 is a convex surface, and the second side surface is a concave surface. The seventh lens L7 has a negative refractive power. The first side surface of the seventh lens L7 is a convex surface, and the second side surface is a concave surface.

[0089] In this embodiment, the first lens L1 is an aspherical lens. By reasonably setting the aspherical lens, it is beneficial to correct distortion and off-axis aberration.

[0090] In this embodiment, the sixth lens L6 and the seventh lens L7 are cemented to form a doublet lens.

[0091] In this embodiment, the effective focal length EFL of the projection lens is 138.0 mm, the relative aperture FNO of the projection lens is 2.8, the back focal length BFL of the projection lens is 122.0 mm, and the field of view FOV of the projection lens is 57°.

[0092] Table 5 below shows the basic structural parameter table of the projection lens in Embodiment 3.

[0093] Table 5

[0094]

[0095]

[0096] Table 6 shows the polynomial coefficients of the aspherical surfaces that can be used in Embodiment 3. Among them, each aspherical surface type can be defined by the formula (1) given in Embodiment 1 above.

[0097] Table 6

[0098] K <![CDATA[α2]]> <![CDATA[α3]]> <![CDATA[α4]]> <![CDATA[α5]]> <![CDATA[α6]]> <![CDATA[α7]]> <![CDATA[α8]]> <![CDATA[α9]]> <![CDATA[α 10 > S1 0.00E+00 -4.81E-06 1.56E-08 -8.15E-11 2.21E-13 -3.83E-16 4.21E-19 -2.86E-22 1.09E-25 -1.80E-29 S2 0.00E+00 -1.07E-06 1.31E-08 -7.98E-11 2.50E-13 -5.00E-16 6.34E-19 -4.89E-22 2.10E-25 -3.83E-29

[0099] As Figure 9 shown, it shows the field curvature diagram of the projection lens in Embodiment 3. As Figure 10 shown, it shows the distortion diagram of the projection lens in Embodiment 3. From Figure 9 and Figure 10 it can be seen that the projection lens of this embodiment can achieve good imaging quality.

[0100] Embodiment 4

[0101] As Figures 11 to 13 shown, it describes the projection lens of Embodiment 4.

[0102] As Figure 11 shown, it is a schematic structural diagram of the projection lens of Embodiment 4. The projection lens sequentially includes, along the optical axis, from the first side to the second side: a first lens L1, a second lens L2, a third lens L3, a stop STOP, a fourth lens L4, a fifth lens L5, a sixth lens L6, a Fresnel lens 10, and an LCD chip 20.

[0103] In this embodiment, the first lens L1 has a negative refractive power. The first side surface of the first lens L1 is convex, and the second side surface is concave. The second lens L2 has a positive refractive power. The first side surface of the second lens L2 is convex, and the second side surface is convex. The third lens L3 has a negative refractive power. The first side surface of the third lens L3 is convex, and the second side surface is concave. The fourth lens L4 has a positive refractive power. The first side surface of the fourth lens L4 is convex, and the second side surface is convex. The fifth lens L5 has a positive refractive power. The first side surface of the fifth lens L5 is concave, and the second side surface is convex. The sixth lens L6 has a negative refractive power. The first side surface of the sixth lens L6 is concave, and the second side surface is concave.

[0104] In this embodiment, the first lens L1 is an aspherical lens. By reasonably setting the aspherical lens, it is beneficial to correct distortion and off-axis aberration.

[0105] In this embodiment, the fifth lens L5 and the sixth lens L6 are cemented to form a doublet lens.

[0106] In this embodiment, the effective focal length EFL of the projection lens is 140.0 mm, the relative aperture FNO of the projection lens is 2.8, the back focal length BFL of the projection lens is 122.0 mm, and the field of view FOV of the projection lens is 57°.

[0107] The following Table 7 shows the basic structural parameter table of the projection lens of Embodiment 4.

[0108] Table 7

[0109] Type Surface Radius of Curvature (mm) Thickness (mm) Refractive Index Abbe Number L1 S1 45.32 6.91 1.49 57 S2 35.71 22.79 L2 S3 342.47 10.24 1.70～1.75 50～55 S4 -149.53 1.29 L3 S5 92.81 10.13 1.70～1.80 25～30 S6 54.84 11.45 STOP S7 Infinity 8.58 L4 S8 177.95 12.09 1.79～1.84 42～50 S9 -105.92 1.00 L5 S10 -1483.24 10.43 1.70～1.75 50～55 L6 S11 -49.00 3.00 1.60～1.65 33～40 S12 71.47 0.00 Fresnel Lens S15 Infinity 1.80 1.58 30.4 S16 -65.04 4.00 PANEL S17 Infinity -

[0110] Table 8 shows the polynomial coefficients that can be used for each aspherical mirror surface in Embodiment 4. Among them, each aspherical surface type can be defined by the formula (1) given in Embodiment 1 above.

[0111] Table 8

[0112] K <![CDATA[α2]]> <![CDATA[α3]]> <![CDATA[α4]]> <![CDATA[α5]]> <![CDATA[α6]]> <![CDATA[α7]]> <![CDATA[α8]]> <![CDATA[α9]]> <![CDATA[α 10 > S1 0.00E+00 -2.80E-06 -3.22E-09 5.40E-12 -1.56E-14 2.81E-17 -3.00E-20 1.93E-23 -6.95E-27 1.08E-30 S2 0.00E+00 -3.15E-06 -3.80E-09 5.25E-13 2.69E-15 -2.04E-17 5.09E-20 -6.32E-23 3.93E-26 -1.01E-29

[0113] As Figure 12 shown, the field curvature diagram of the projection lens of Embodiment 4 is shown. As Figure 13 shown, the distortion diagram of the projection lens of Embodiment 4 is shown. From Figure 12 and Figure 13 it can be seen that the projection lens of this embodiment can achieve good imaging quality.

[0114] Obviously, the above-described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0115] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should also be understood that when the terms "comprising" and / or "including" are used in this specification, they specify the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0116] It should be noted that the terms "first", "second", etc. in the specification, claims and above-mentioned drawings of the present application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein.

[0117] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A projection lens, characterized in that, It sequentially includes a first lens (L1), a second lens (L2), a third lens (L3), a fourth lens (L4), a fifth lens (L5), a sixth lens (L6), a Fresnel lens (10), and an LCD chip (20) from the first side to the second side along the optical axis. Among them, the fifth lens (L5) has a positive diopter; the total optical length TTL of the projection lens and the effective focal length EFL of the projection lens satisfy: TTL / EFL≥2.

80.

2. The projection lens according to claim 1, characterized in that, The effective focal length EFL of the projection lens and the back focal length BFL of the projection lens satisfy: BFL / EFL≥1.0; and / or the total optical length TTL of the projection lens satisfies: TTL≤200mm.

3. The projection lens according to claim 1, characterized in that, The effective focal length EFL of the projection lens satisfies: 120mm≤EFL≤140mm; and / or The relative aperture FNO of the projection lens satisfies: 2.0≤FNO≤3.

5.

4. The projection lens according to claim 1, characterized in that, The telecentric angle TA of the projection lens satisfies: TA≤3.0°; and / or The field of view FOV of the projection lens satisfies: FOV≥66°.

5. The projection lens according to claim 1, characterized in that, The ratio TR between the projection distance and the picture width of the projection lens satisfies: 1.1≤TR≤1.3; and / or the size of the LCD chip (20) is less than 5.6 inches.

6. The projection lens according to claim 1, characterized in that, The projection lens further includes a stop (STOP), and the stop (STOP) is disposed between the third lens (L3) and the fourth lens (L4), between the second lens (L2) and the third lens (L3), or between the fourth lens (L4) and the fifth lens (L5).

7. The projection lens according to claim 6, characterized in that, There is at least one doublet lens between the stop (STOP) and the LCD chip (20); and / or at least one meniscus aspheric lens is disposed on the first side of the stop (STOP), and at least one set of lenses with positive and negative diopters is disposed on the second side of the stop (STOP).

8. The projection lens according to claim 6, characterized in that, At least one plastic lens is disposed on the first side of the stop (STOP), and / or at least one set of lenses with positive and negative diopters is disposed on the first side of the stop (STOP).

9. The projection lens according to claim 6, characterized in that, The lenses between the stop (STOP) and the LCD chip (20) form a second group, and the stop (STOP) is located at the focal position of the second group.

10. The projection lens according to any one of claims 1 to 9, characterized in that, The resolution of the LCD chip (20)=1 / (2*X)*1000; Wherein, X is the pixel size of the LCD chip (20), and X is greater than or equal to 30um.

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