Projection lens for LCD projection

Abstract

The invention relates to the technical field of projection lenses, in particular to a projection lens for liquid crystal display (LCD) projection, which comprises a convex-concave negative lens, a convex-concave positive lens, a biconcave negative lens, a biconvex aspheric positive lens, a convex-concave aspheric negative lens and a Fresnel lens, the biconcave negative lens is located between the convex-concave positive lens and the biconvex aspheric positive lens, and the biconvex aspheric positive lens is located between the biconcave negative lens and the convex-concave aspheric negative lens; by adopting an optical structure combined by five groups of lenses, the projection ratio of the projection lens is 0.69: 1; according to the utility model, the projection distance is 0.31 m, the projection picture can be 20 ''when the projection distance is 0.31 m, the requirement on the space size is low when the lens is used, the two groups of lenses adopt aspheric lenses formed by optical plastic injection molding, the adoption of the lenses corrects off-axis aberration and optical relative distortion caused by the enlargement of a field of view, the processing manufacturability is good, the cost is low, and the requirement of mass production can be met.

Description

Technical Field

[0001] The invention relates to the field of projection lenses, in particular to a projection lens used for LCD projection. Background Art

[0002] LCD single-chip projectors have a simple structure and low cost, and their sales are very large. In recent years, due to the development of LCD chip manufacturing technology, the resolution has been greatly improved. At present, the pixel point of LCD 2.1-inch chip can reach 1280x720P. The improvement of resolution has expanded the scope of use of projectors, expanding the game console market to the entertainment market and product exhibition advertising market, and even entering the home to replace TV sets. The projection lens is one of the important components of LCD projection.

[0003] The existing single-chip LCD projection lens is formed by combining multiple groups of projection lenses, and the projection ratio is generally 1.3 to 1.6. Taking a projection ratio of 1.4 as an example, if you want to project a 100-inch large screen, the front edge of the machine lens surface needs to be about 3.1m away from the screen.

[0004] However, the prior art has defects. Its projection is relatively large. When used, it has high requirements on the size of the projection space and is not suitable for use in small spaces. In addition, the increase in the field of view of the projection lens in the prior art will produce off-axis aberrations and optical relative distortion, which will affect the projection effect of the LCD projector. Therefore, a projection lens for LCD projection is proposed. Summary of the invention

[0005] The object of the present invention is to provide a projection lens for LCD projection to solve the problems raised in the above background technology.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A projection lens for LCD projection comprises a convex-concave negative lens, a convex-concave positive lens, a double concave negative lens, a double convex aspheric positive lens, a convex-concave aspheric negative lens and a Fresnel lens. The convex-concave positive lens is located between the convex-concave negative lens and the double concave negative lens, the double concave negative lens is located between the convex-concave positive lens and the double convex aspheric positive lens, the double convex aspheric positive lens is located between the double concave negative lens and the convex-concave aspheric negative lens, the convex-concave aspheric negative lens is located between the double convex aspheric positive lens and the Fresnel lens, an aperture light bar is arranged between the convex-concave positive lens and the double concave negative lens, and both the double convex aspheric positive lens and the convex-concave aspheric negative lens are injection molded by optical plastics.

[0008] Preferably, the radius range of R1 of the convex-concave negative lens is 79-81 mm, the radius range of R2 is 25.8-26.3 mm, the thickness t is 1.9-2.1 mm, the refractive index n is 1.62-1.65, and the air space d is 27.5-28.2 mm.

[0009] Preferably, the radius range of R3 of the convex-concave positive lens is 21.5-22.9 mm, the radius range of R4 is 605.5-615.5 mm, the thickness t is 8.1-8.4 mm, the refractive index n is 1.69-1.73, and the air gap d is 4.5-4.9 mm.

[0010] Preferably, the diameter of the aperture light stop is in the range of 15.9-16.1 mm, and the air gap d is in the range of 3.55-3.95 mm.

[0011] Preferably, the radius range of R6 of the biconcave negative lens is -27.3-28.1 mm, the radius range of R7 is 138.8-140.5 mm, the thickness t is 1.38-1.53 ​​mm, the refractive index n is 1.79-1.81, and the air space d is 0.15-0.25 mm.

[0012] Preferably, the radius range of R8 of the biconvex aspheric positive lens is 70.15-70.78 mm, the thickness t is 6.8-7.3 mm, the refractive index n is 1.51-1.55, the air gap d is 0.15-0.21 mm, and the radius range of R9 is -15.15-15.56 mm.

[0013] Preferably, the radius range of R10 of the convex-concave aspheric negative lens is 19.25-19.91 mm, the thickness t is 2.35-2.63 mm, the refractive index n is 1.51-1.55, the radius range of R11 is 13.15-13.35 mm, and the air gap d is 31.77-32.05 mm.

[0014] Preferably, the radius of R12 of the Fresnel lens is a plane, the thickness t is 1.6-2.1 mm, the refractive index n is 1.47-1.51, the radius range of R13 is 22.15-22.85 mm, the tooth spacing range is 0.15-0.25 mm, and the air spacing d is 6.15-6.65 mm.

[0015] Beneficial effects of the present invention:

[0016] The present invention adopts an optical structure composed of 5 lens groups, and the projection ratio of the projection lens is 0.69:1. The projection screen can be 20" at a projection distance of 0.31m, and the space requirement is relatively low when in use. Two groups of lenses adopt aspheric lenses molded by optical plastic injection. The use of such lenses corrects the off-axis aberration and optical relative distortion caused by the increase of the field of view, has good processing technology, and is low in cost, which can meet the requirements of mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 It is an arrangement diagram of optical glass with light of the present invention;

[0019] Figure 2 It is a radius arrangement diagram without light of the present invention;

[0020] Figure 3 is the diffuse speckle SPT data of the present invention;

[0021] Figure 4 is the optical transfer function curve of the present invention;

[0022] Figure 5 is a magnification chromatic aberration curve diagram of the present invention;

[0023] Figure 6 is a graph of the optical relative distortion of the present invention;

[0024] The reference numerals in the figures are as follows:

[0025] 1. Convex-concave negative lens; 2. Convex-concave positive lens; 3. Aperture stop; 4. Biconcave negative lens; 5. Biconvex aspheric positive lens; 6. Convex-concave aspheric negative lens; 7. Fresnel lens. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] A projection lens for LCD projection, such as Figure 1-Figure 6As shown, it includes a convex-concave negative lens 1, a convex-concave positive lens 2, a biconcave negative lens 4, a biconvex aspheric positive lens 5, a convex-concave aspheric negative lens 6, and a Fresnel lens 7. The convex-concave positive lens 2 is located between the convex-concave negative lens 1 and the biconcave negative lens 4, the biconcave negative lens 4 is located between the convex-concave positive lens 2 and the biconvex aspheric positive lens 5, the biconvex aspheric positive lens 5 is located between the biconcave negative lens 4 and the convex-concave aspheric negative lens 6, the convex-concave aspheric negative lens 6 is located between the biconvex aspheric positive lens 5 and the Fresnel lens 7, an aperture diaphragm 3 is provided between the convex-concave positive lens 2 and the biconcave negative lens 4, and the biconvex aspheric positive lens 5 and the convex-concave aspheric negative lens 6 are both injection molded by optical plastics.

[0028] The five lens groups and the Fresnel lens 7 are installed in sequence in the LCD projector. The aperture diaphragm 3 is installed between the convex-concave positive lens 2 and the double-concave negative lens 4. The light source is located on the side of the convex-concave negative lens 1 away from the convex-concave positive lens 2. The light passes through the convex-concave negative lens 1, the convex-concave positive lens 2, the double-concave negative lens 4, the double-convex aspheric positive lens 5, the convex-concave aspheric negative lens 6, and the Fresnel lens 7 with high-order terms in sequence. The refraction is as follows: Figure 2 shown.

[0029] Through the use of an optical structure composed of 5 groups of lenses, the projection ratio of the projection lens is 0.69:1, and the projection screen can be 20" at a projection distance of 0.31m. The space requirement is relatively low when in use, and it can be installed on the desktop as a learning machine, which can replace a small tablet computer. Two groups of lenses use aspheric lenses molded by optical plastic injection. The use of this lens corrects the off-axis aberration and optical relative distortion caused by the increase in the field of view. It has good processing technology and low cost, which can meet the requirements of mass production.

[0030] The present invention is applicable to a single-chip LCD projection optical machine, the LCD chip size is 2.1 inches, the pixel point is: 1280x720P, the projection ratio is 0.69:1, the bias is 100%, the optical transfer function MTF@14Lp≥0.3, the TV distortion is ≤0.3%, the magnification chromatic aberration is ≤20λm, and it can work continuously at a temperature of ≤80°.

[0031] The focal length of the convex-concave negative lens 1 is fa; the focal length of the convex-concave positive lens 2 is fb; the focal length of the double-concave negative lens 4 is fc; the focal length of the double-convex aspheric positive lens 5 is fd; the focal length of the convex-concave aspheric negative lens 6 is fe, and the focal length of the Fresnel lens 7 is ff.

[0032] The main performance indicators of the short throw ratio rear projection lens of the present invention are: effective focal length f'=35.19mm, relative aperture F=2.64, rear working distance LF'=40.27mm, total length of the optical system 98.6mm, and resolution of 1280x720P pixels.

[0033] like Figure 1-Figure 6 As shown, the radius range of R1 of the convex-concave negative lens 1 is 79-81 mm, the radius range of R2 is 25.8-26.3 mm, the thickness t is 1.9-2.1 mm, the refractive index n is 1.62-1.65, and the air space d is 27.5-28.2 mm. The lens processing should be strictly controlled according to the above data.

[0034] like Figure 1-Figure 6 As shown, the radius range of R3 of the convex-concave positive lens 2 is 21.5-22.9 mm, the radius range of R4 is 605.5-615.5 mm, the thickness t is 8.1-8.4 mm, the refractive index n is 1.69-1.73, the air space d is 4.5-4.9 mm, and when installing the convex-concave positive lens 2 and other lenses, it should be avoided to install the lenses upside down and to avoid inverting the positive and negative.

[0035] like Figure 1-Figure 6 As shown, the diameter range of the aperture light barrier 3 is 15.9-16.1 mm, the air interval d is 3.55-3.95 mm, and the aperture light barrier 3 is installed between the convex-concave positive lens 2 and the double concave negative lens 4.

[0036] like Figure 1-Figure 6 As shown, the radius range of R6 of the double concave negative lens 4 is -27.3-28.1 mm, the radius range of R7 is 138.8-140.5 mm, the thickness t is 1.38-1.53 ​​mm, the refractive index n is 1.79-1.81, the air gap d is 0.15-0.25 mm, and the double concave negative lens 4 is close to the double convex aspheric positive lens 5.

[0037] like Figure 1-Figure 6 As shown, the radius range of R8 of the biconvex aspheric positive lens 5 is 70.15-70.78 mm, the thickness t is 6.8-7.3 mm, the refractive index n is 1.51-1.55, the air gap d is 0.15-0.21 mm, and the radius range of R9 is -15.15-15.56 mm.

[0038] The standard equation for an aspheric surface is as follows:

[0039]

[0040] In the above formula, C = 1 / R.

[0041] The radius range of R8 is 70.15-70.78mm, K=-1;

[0042] A1=0;

[0043] A2=1.7384327E-005;

[0044] A3 = -4.3251934E-007;

[0045] A4=8.6127748E-009;

[0046] A5 = -4.2544656E-011;

[0047] A6 = 7.4143915E-014;

[0048] A7=0;

[0049] The thickness t is 6.8-7.3 mm, the refractive index n is in the range of 1.51-1.55; the air gap d is in the range of 0.15-0.21 mm.

[0050] The radius range of R9 is -15.15-15.56mm, K=-2.04065;

[0051] A1=0;

[0052] A2=6.6521894E-005;

[0053] A3 = -3.0647421E-007;

[0054] A4 = -2.0890194E-009;

[0055] A5=6.8123854E-011;

[0056] A6 = -2.2683112E-013;

[0057] A7=0;

[0058] like Figure 1-Figure 6 As shown, the radius range of R10 of the convex-concave aspheric negative lens 6 is 19.25-19.91 mm, the thickness t is 2.35-2.63 mm, the refractive index n is 1.51-1.55, the radius range of R11 is 13.15-13.35 mm, and the air gap d is 31.77-32.05 mm.

[0059] The radius range of R10 is 19.25-19.91mm, K=-18.55335;

[0060] A1=0;

[0061] A2=7.282503E-006;

[0062] A3 = -2.3438812E-007;

[0063] A4=1.7758118E-009;

[0064] A5 = -4.0538795E-012;

[0065] A6=2.2476735E-015;

[0066] A7=0;

[0067] The thickness t is 2.35-2.63 mm; the refractive index n ranges from 1.51-1.55.

[0068] The radius range of R11 is 13.15-13.35mm, K=-8.532375;

[0069] A1=0;

[0070] A2=-2.5890717E-005;

[0071] A3=1.5330088E-007;

[0072] A4 = -7.6885275E-010;

[0073] A5=3.1022559E-012;

[0074] A6 = -4.7757313E-015;

[0075] A7=0;

[0076] The air gap d ranges from 31.77 to 32.05 mm.

[0077] like Figure 1-Figure 6 As shown, the radius of R12 of the Fresnel lens 7 is a plane, the thickness t is 1.6-2.1 mm, the refractive index n is 1.47-1.51, the radius range of R13 is 22.15-22.85 mm, the tooth spacing range is 0.15-0.25 mm, and the air spacing d is 6.15-6.65 mm.

[0078] The radius range of R13 is 22.15-22.85mm; K=-1; the tooth spacing range is 0.15-0.25mm;

[0079] A1=0;

[0080] A2=4.1816E-006;

[0081] A3=-5.8183E-009;

[0082] A4=1.6399E-012;

[0083] A5=0;

[0084] A6=0;

[0085] A7=0;

[0086] The air gap d ranges from 6.15 to 6.65 mm.

[0087] The working principle of a projection lens for LCD projection provided by the present invention is as follows:

[0088] Through the use of an optical structure composed of 5 groups of lenses, the projection ratio of the projection lens is 0.69:1, and the projection screen can be 20" at a projection distance of 0.31m. The space requirement is relatively low when in use. Two groups of lenses use aspherical lenses molded by optical plastic injection. The use of this lens corrects the off-axis aberration and optical relative distortion caused by the increase in the field of view. It has good processing technology and low cost, which can meet the requirements of mass production.

[0089] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A projection lens for LCD projection, comprising a convex-concave negative lens (1), a convex-concave positive lens (2), a double-concave negative lens (4), a double-convex aspheric positive lens (5), a convex-concave aspheric negative lens (6), and a Fresnel lens (7), characterized in that: The convexoconcave positive lens (2) is located between the convexoconcave negative lens (1) and the biconcave negative lens (4); the biconcave negative lens (4) is located between the convexoconcave positive lens (2) and the biconvex aspheric positive lens (5); the biconvex aspheric positive lens (5) is located between the biconcave negative lens (4) and the convexoconcave aspheric negative lens (6); the convexoconcave aspheric negative lens (6) is located between the biconvex aspheric positive lens (5) and the Fresnel lens (7); an aperture light barrier (3) is provided between the convexoconcave positive lens (2) and the biconcave negative lens (4); and both the biconvex aspheric positive lens (5) and the convexoconcave aspheric negative lens (6) are made of optical plastic injection molding.

2. The projection lens for LCD projection according to claim 1, characterized in that: The radius range of R1 of the convexoconcave negative lens (1) is 79-81 mm, the radius range of R2 is 25.8-26.3 mm, the thickness t is 1.9-2.1 mm, the refractive index n is 1.62-1.65, and the air interval d is 27.5-28.2 mm.

3. The projection lens for LCD projection according to claim 1, characterized in that: The radius range of R3 of the convex-concave positive lens (2) is 21.5-22.9 mm, the radius range of R4 is 605.5-615.5 mm, the thickness t is 8.1-8.4 mm, the refractive index n is 1.69-1.73, and the air interval d is 4.5-4.9 mm.

4. The projection lens for LCD projection according to claim 1, characterized in that: The diameter of the aperture light barrier (3) is in the range of 15.9-16.1 mm, and the air interval d is in the range of 3.55-3.95 mm.

5. The projection lens for LCD projection according to claim 1, characterized in that: The radius range of R6 of the biconcave negative lens (4) is -27.3-28.1 mm, the radius range of R7 is 138.8-140.5 mm, the thickness t is 1.38-1.53 ​​mm, the refractive index n is 1.79-1.81, and the air interval d is 0.15-0.25 mm.

6. The projection lens for LCD projection according to claim 1, characterized in that: The radius range of R8 of the biconvex aspheric positive lens (5) is 70.15-70.78 mm, the thickness t is 6.8-7.3 mm, the refractive index n is 1.51-1.55, the air interval d is 0.15-0.21 mm, and the radius range of R9 is -15.15-15.56 mm.

7. The projection lens for LCD projection according to claim 1, characterized in that: The radius range of R10 of the convex-concave aspheric negative lens (6) is 19.25-19.91 mm, the thickness t is 2.35-2.63 mm, the refractive index n is 1.51-1.55, the radius range of R11 is 13.15-13.35 mm, and the air interval d is 31.77-32.05 mm.

8. The projection lens for LCD projection according to claim 1, characterized in that: The radius of R12 of the Fresnel lens (7) is a plane, the thickness t is 1.6-2.1 mm, the refractive index n is 1.47-1.51, the radius range of R13 is 22.15-22.85 mm, the tooth spacing range is 0.15-0.25 mm, and the air spacing d is 6.15-6.65 mm.

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