WO2023092421A1 - 光学系统及vr显示设备 - Google Patents

光学系统及vr显示设备 Download PDF

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Publication number
WO2023092421A1
WO2023092421A1 PCT/CN2021/133282 CN2021133282W WO2023092421A1 WO 2023092421 A1 WO2023092421 A1 WO 2023092421A1 CN 2021133282 W CN2021133282 W CN 2021133282W WO 2023092421 A1 WO2023092421 A1 WO 2023092421A1
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Prior art keywords
power lens
refractive index
convex surface
optical system
lens
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PCT/CN2021/133282
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English (en)
French (fr)
Inventor
白家荣
董瑞君
武玉龙
王晨如
栗可
韩娜
马占山
陈丽莉
Original Assignee
京东方科技集团股份有限公司
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Application filed by 京东方科技集团股份有限公司 filed Critical 京东方科技集团股份有限公司
Priority to PCT/CN2021/133282 priority Critical patent/WO2023092421A1/zh
Priority to CN202180003588.4A priority patent/CN116507958A/zh
Publication of WO2023092421A1 publication Critical patent/WO2023092421A1/zh

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B25/00—Eyepieces; Magnifying glasses
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/01—Head-up displays

Definitions

  • the present disclosure relates to the field of display technology, in particular to an optical system and a VR display device.
  • VR Virtual reality
  • VR Virtual Reality
  • 3-dimensional design involving many disciplines, it integrates computer simulation, three-dimensional design, image processing, pattern recognition, microelectronics and parallel processing technology, using virtual reality hardware equipment and computer systems to create a realistic virtual environment. Users experience the same feelings in the virtual space as in the real world, such as vision, hearing, touch, smell, collision, movement and handling dynamic interaction, etc.
  • VR display devices are developing in the direction of large field of view and thinner and thinner, so as to bring better immersion to viewers and improve user experience.
  • an optical system having an optical axis.
  • the optical system includes a positive power lens, a negative power lens and a display arranged in sequence along the optical axis.
  • the positive power lens includes a first convex surface far away from the display, and a second convex surface close to the display, both of the first convex surface and the second convex surface are outside the optical center of the positive power lens convex.
  • the negative power lens includes a third convex surface away from the display, and a fourth concave surface close to the display, the third convex surface is convex relative to the optical center of the negative power lens, and the first The four concave surfaces are concave relative to the optical center of the negative power lens.
  • the refractive index of one of them is greater than the refractive index of the other, and the larger refractive index is the first refractive index, which is higher than that of the other.
  • the small refractive index is a second refractive index, the first refractive index is greater than 1.7, the second refractive index is greater than 1.5, and the ratio of the first refractive index to the second refractive index is less than or equal to 2.
  • the radius of curvature of the fourth concave surface of the negative power lens is smaller than the radius of curvature of the third convex surface.
  • the radius of curvature of the fourth concave surface is greater than 0 and less than or equal to 50 mm; the radius of curvature of the third convex surface is greater than 0 and less than or equal to 100 mm.
  • the negative power lens includes a central portion proximate the optical axis, and a peripheral portion surrounding the central portion. Along the optical axis, the thickness of the middle portion is smaller than the thickness of the edge portion.
  • the ratio of the first refractive index to the second refractive index is less than or equal to 1.1.
  • the refractive power range of the positive refractive power lens is 0.05 mm ⁇ 1 to 0.15 mm ⁇ 1 .
  • the refractive index of the positive power lens is greater than the refractive index of the negative power lens.
  • the negative power lens has a power range of -0.1mm -1 to -0.02mm -1 .
  • the first refractive index is N 1 and the second refractive index is N 2 .
  • the distance between the second convex surface of the positive power lens and the third convex surface of the negative power lens is D. in,
  • the distance between the second convex surface of the positive power lens and the third convex surface of the negative power lens ranges from 0.5 mm to 0.55 mm.
  • the distance between the apex of the first convex surface of the positive power lens and the surface of the display away from the negative power lens is less than or equal to 35 mm.
  • the refractive index of the positive power lens is N a
  • the dispersion coefficient is V a
  • the refractive index of the negative power lens is N b
  • the dispersion coefficient is V b . in, and One of them is greater than the other, and the ratio of the larger one to the smaller one is less than or equal to 2.5.
  • the first convex surface, the second convex surface, the third convex surface and the fourth concave surface are all aspherical surfaces.
  • the first convex surface, the second convex surface, the third convex surface and the fourth concave surface are all even-order aspheric surfaces.
  • the surface equations of the first convex surface, the second convex surface, the third convex surface and the fourth concave surface are Wherein, Z is the vertical distance between the point of the lens surface and the first reference surface, and the first reference surface is tangent to the apex of the lens surface; c is the curvature at the apex of the lens surface; k is the quadric surface coefficient of the lens surface ; r is the vertical distance between a point on the lens surface and the optical axis; A 2i is a polynomial coefficient; i ⁇ 1, and is an integer.
  • the material of the positive power lens includes glass, and the material of the negative power lens includes plastic.
  • the mass of the positive power lens is greater than the mass of the negative power lens.
  • the optical system further includes a fixed part and a moving part, and the positive power lens and the negative power lens are arranged on the fixed part.
  • the moving part is slidably connected with the fixing part, the display is arranged on the moving part, and the moving part is configured to drive the display to move along the optical axis.
  • a VR display device in another aspect, includes: the optical system as described in any one of the above embodiments.
  • FIG. 1 is a block diagram of an optical system according to some embodiments
  • Fig. 2 is the partial enlarged view of the optical system in Fig. 1 at M place;
  • Figure 3 is an optical diagram of an optical system according to some embodiments.
  • FIG. 4 is a structural diagram of a positive power lens of an optical system according to some embodiments.
  • Fig. 5 is a sectional view of the positive power lens in Fig. 4 along the section line A-A';
  • FIG. 6 is a structural diagram of a negative power lens of an optical system according to some embodiments.
  • Fig. 7 is a sectional view of the negative power lens in Fig. 6 along the section line B-B';
  • Figure 8 is a spot diagram of an optical system according to some embodiments.
  • Figure 9 is a field curvature diagram of an optical system according to some embodiments.
  • Figure 10 is a distortion diagram of an optical system according to some embodiments.
  • FIG. 11 is another structural diagram of an optical system according to some embodiments.
  • Fig. 12 is another structural diagram of an optical system according to some embodiments.
  • Figure 13 is a block diagram of a VR display device according to some embodiments.
  • first and second are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of indicated technical features. Thus, a feature defined as “first” and “second” may explicitly or implicitly include one or more of these features. In the description of the embodiments of the present disclosure, unless otherwise specified, "plurality” means two or more.
  • connection When describing some embodiments, the expression “connected” and its derivatives may be used. For example, the term “connected” may be used in describing some embodiments to indicate that two or more elements are in direct physical or electrical contact with each other.
  • perpendicular includes the stated conditions as well as close approximations to the stated conditions within acceptable deviations as defined by the art As determined by one of ordinary skill taking into account the measurement in question and the errors associated with the measurement of the particular quantity (ie, limitations of the measurement system). For example, “perpendicular” includes absolute vertical and approximate vertical, wherein the acceptable deviation range of approximate vertical may also be within 5°, for example.
  • Exemplary embodiments are described herein with reference to cross-sectional and/or plan views that are idealized exemplary drawings.
  • the thickness of layers and regions are exaggerated for clarity. Accordingly, variations in shape from the drawings as a result, for example, of manufacturing techniques and/or tolerances are contemplated.
  • example embodiments should not be construed as limited to the shapes of regions illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, an etched region illustrated as a rectangle will, typically, have curved features.
  • the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the actual shape of a region of a device and are not intended to limit the scope of example embodiments.
  • the VR display device includes a reflective pancake structure, and the thickness of the display device can be reduced by adopting this structural design, but the light extraction efficiency of the display device is low (the light output efficiency is less than 25%). , and there are problems of "ghosting" and a small viewing angle in the viewing picture, which leads to poor visual experience for the viewer.
  • some embodiments of the present disclosure provide an optical system 100.
  • the optical system 100 has an optical axis A, and the optical axis A is the symmetry axis of the optical system 100.
  • the optical system 100 includes a positive power lens 1, a negative power lens 2 and a display 3 arranged in sequence along the optical axis A, and the optical center C1 of the positive power lens 1, the negative power lens
  • the optical center C2 of 2 and the center C3 of the display 3 are both located on the optical axis A.
  • the refractive power of the "positive power lens 1" is greater than 0, and the light rays converge after being refracted by the positive power lens 1 .
  • the refractive power of the "negative refractive power lens 2" is less than 0, and the light diverges after being refracted by the negative refractive power lens 2.
  • the positive refractive power lens 1 includes a first convex surface 11 away from the display 3, and a second convex surface 12 close to the display 3, the first convex surface 11 and the second convex surface 12 are all relative to the light of the positive refractive power lens 1.
  • the heart C1 is convex.
  • the negative refractive power lens 2 includes a third convex surface 21 away from the display 3, and a fourth concave surface 22 close to the display 3, and the third convex surface 21 is convex outward relative to the optical center C2 of the negative refractive power lens 2 , the fourth concave surface 22 is concave relative to the optical center C2 of the negative power lens 2 .
  • the refractive index of the positive refractive power lens 1 and the refractive index of the negative refractive power lens 2 one of them has a higher refractive index than the other.
  • the larger refractive index is referred to as “the first” First refractive index”
  • the smaller refractive index is called “second refractive index”
  • the first refractive index is greater than 1.7
  • the second refractive index is greater than 1.5
  • the ratio of the first refractive index to the second refractive index is less than or equal to 2 .
  • the focal length of the optical system 100 ranges from 20mm to 35mm, for example, the focal length of the optical system 100 is 20mm, 25mm, 28mm, 30mm or 35mm.
  • the optical system 100 adopts a structural design in which a positive power lens 1 and a negative power lens 2 are combined, which can reduce the viewing image of the optical system 100 (optical system 100 ).
  • the spherical aberration, curvature of field and other aberrations in the imaging of the human eye 4 can reduce the stray light in the light output of the optical system 100, so as to improve the "ghost image" and glare problems of the picture, improve the picture quality, and enhance the viewing experience of the viewer. immersion, and the optical system 100 has a high light extraction efficiency.
  • the fourth concave surface 22 of the negative refractive power lens 2 is concave relative to the optical center C2 of the negative refractive power lens 2 , so as to collect light rays with a relatively large angle emitted by the display 3 .
  • the refractive index of positive refractive power lens 1 and the refractive index of negative refractive power lens 2 are set to, wherein the refractive index of one is greater than the refractive index of the other, and the larger refractive index is the first refractive index, and the smaller The refractive index is the second refractive index, the first refractive index is greater than 1.7, the second refractive index is greater than 1.5, and the ratio of the first refractive index to the second refractive index is less than or equal to 2.
  • the positive power lens 1 And the negative power lens 2 can refract the light rays with larger angles into the human eye 4 in a shorter distance (the focal length of the optical system 100), thereby increasing the viewing angle of the viewing picture of the optical system 100 (for example , the viewing angle is greater than or equal to 90°), and the optical system 100 can be made thinner.
  • the positive power lens 1 , the negative power lens 2 , the display 3 in the optical system 100 , and the relationship between the three are explained below with reference to the accompanying drawings.
  • the refractive power of the positive refractive lens 1 is greater than 0, and the refractive power of the positive refractive lens 1 ranges from 0.05 mm ⁇ 1 to 0.15 mm ⁇ 1 , for example, The refractive power of the positive refractive power lens 1 is 0.05mm -1 , 0.07mm -1 , 0.1mm -1 , 0.12mm -1 or 0.15mm -1 .
  • the first convex surface 11 of the positive power lens 1 may be spherical or aspheric, and the second convex surface 12 may be spherical or aspherical.
  • spherical surface means that the radius of curvature is constant everywhere on the surface of the lens. Taking the first convex surface 11 as an example, “aspheric surface” refers to the lens surface from the vertex P1 to the edge, and the radius of curvature of the lens surface gradually increases (the lens surface gradually flattens).
  • both the first convex surface 11 and the second convex surface 12 of the positive power lens 1 are aspherical, which can reduce various aberrations such as spherical aberration, coma, and field curvature of the viewing image of the optical system 100 .
  • the radius of curvature of the first convex surface 11 of the positive power lens 1 is greater than 0 and less than or equal to 100mm, for example, the radius of curvature of the first convex surface 11 is 20mm, 40mm , 60mm, 80mm or 100mm.
  • the radius of curvature of the second convex surface 12 is greater than 0 and less than or equal to 50mm, for example, the radius of curvature of the second convex surface 12 is 10mm, 20mm, 30mm, 40mm or 50mm.
  • the positive power lens 1 includes a central portion a1 near the optical axis A, and an edge portion b1 surrounding the central portion a1 .
  • the thickness of the middle part a1 is greater than that of the edge part b1, that is, the middle part a1 of the positive power lens 1 is thicker and the edge part b1 is thinner.
  • the material of the positive power lens 1 may include glass or plastic.
  • the refractive power of the negative refractive power lens 2 is less than 0, and the refractive power of the negative refractive power lens 2 ranges from -0.1mm -1 to -0.02mm - 1 , for example, the negative power lens 2 has a power of -0.1mm -1 , -0.08mm -1 , -0.06mm -1 , -0.04mm -1 or -0.02mm -1 .
  • the third convex surface 21 of the negative power lens 2 may be spherical or aspheric, and the fourth concave surface 22 may be spherical or aspherical.
  • the third convex surface 21 and the fourth concave surface 22 of the negative power lens 2 are both aspherical, which can reduce various aberrations such as spherical aberration, coma, and field curvature of the viewing image of the optical system 100 .
  • the radius of curvature of the fourth concave surface 22 of the negative power lens 2 is smaller than the radius of curvature of the third convex surface 21 .
  • the fourth concave surface 22 of the negative refractive power lens 2 is concave relative to the optical center C2 of the negative refractive power lens 2, and compared with the curvature radius of the third convex surface 21, the curvature radius of the fourth concave surface 22
  • the setting is smaller, that is, the fourth concave surface 22 is more curved than the third convex surface 21, which is more conducive to the fourth concave surface 22 collecting the light with a larger angle emitted by the display 3, thereby helping to increase the viewing angle of the optical system 100. field of view.
  • the radius of curvature of the third convex surface 21 of the negative refractive power lens 2 is greater than 0 and less than or equal to 100mm, for example, the radius of curvature of the third convex surface 21 is 20mm, 40mm, 60mm, 80mm or 100mm.
  • the radius of curvature of the fourth concave surface 22 is greater than 0 and less than or equal to 50mm, for example, the radius of curvature of the fourth concave surface 22 is 10mm, 20mm, 30mm, 40mm or 50mm.
  • the negative power lens 2 includes a central portion a2 near the optical axis A, and an edge portion b2 surrounding the central portion a2 .
  • the thickness of the middle part a2 is smaller than that of the edge part b2, so that the middle part a2 of the negative power lens 2 is thinner and the edge part b2 is thicker.
  • both surfaces of the negative power lens are concave relative to the optical center, that is, both sides of the negative power lens are concave, so that the middle part of the negative power lens is very thin, and the edge part is very thin.
  • the thickness difference from the middle part is relatively large, resulting in low structural strength of the negative power lens, and the negative power lens is easily broken.
  • the third convex surface 21 of the negative power lens 2 is convex relative to the optical center C2 of the negative power lens 2, which can increase the negative power.
  • the thickness of the middle part a2 of the lens 2 improves the structural strength of the middle part a2 of the negative power lens 2 and avoids the problem that the middle part a2 of the negative power lens 2 is too thin and easily broken.
  • the material of the negative power lens 2 may include glass or plastic.
  • the refractive index of the positive refractive power lens 1 is greater than the refractive index of the negative refractive power lens 2, that is, the refractive index of the positive refractive power lens 1 is greater than 1.7, and the negative refractive power lens 1 is greater than 1.7.
  • the refractive index of lens 2 is greater than 1.5.
  • the refractive power of the positive refractive lens 1 ranges from 0.05mm -1 to 0.15mm -1 , and the refractive power of the positive refractive lens 1 is small, so that the positive refractive lens 1 can refract light rays with a large angle into the human eye4.
  • the positive refractive power lens 1 is used in conjunction with the negative refractive power lens 2 to increase the viewing angle of the viewing image of the optical system 100 .
  • the larger first refractive index is set to N 1
  • the smaller one is set to N 1
  • the second refractive index is set to N 2 .
  • the distance between the second convex surface 12 of the positive power lens 1 and the third convex surface 21 of the negative power lens 2 is set as D.
  • the reasonable value range of the above-mentioned distance D can be determined, and when the distance D is within a reasonable value range, it is guaranteed
  • the length of the optical system 100 is not too long, and the reliability of the assembly between the positive refractive power lens 1 and the negative refractive power lens 2 is guaranteed.
  • the length of the optical system 100 refers to the apex P1 of the first convex surface 11 of the positive power lens 1 along the optical axis A, and the surface 31 of the negative power lens 2 away from the display 3 distance.
  • the distance D between the second convex surface 12 of the positive power lens 1 and the third convex surface 21 of the negative power lens 2 ranges from 0.5 mm to 0.55 mm.
  • the distance D can be 0.51mm, 0.52mm, 0.53mm, 0.54mm or 0.55mm.
  • the distance D is less than 0.5 mm, it means that the distance between the second convex surface 12 and the third convex surface 21 is too small, that is, the distance between the positive power lens 1 and the negative power lens 2 is too small, which means Difficulty in assembling between the positive power lens 1 and the negative power lens 2 may result. If the distance D is greater than 0.55 mm, it means that the distance between the second convex surface 12 and the third convex surface 21 is too large, that is, the distance between the positive power lens 1 and the negative power lens 2 is too large, which may cause the optical system 100 The length of is too long, which is not conducive to thinning the optical system 100 .
  • the distance between the apex P1 of the first convex surface 11 of the positive power lens 1 and the surface 31 of the display 3 away from the negative power lens 2 is less than or equal to 35mm , that is, the length of the optical system 100 is less than or equal to 35 mm.
  • the length of the optical system 100 is 31mm, 32mm, 33mm, 34mm or 35mm.
  • the refractive index of the positive power lens 1 is set as N a
  • the dispersion coefficient is set as V a
  • the refractive index of the negative power lens 2 is N b
  • the dispersion coefficient is V b . in, and One of them is greater than the other, and the ratio of the larger one to the smaller one is less than or equal to 2.5, for example, and The ratio of the larger one to the smaller one is 2.1, 2.2, 2.3, 2.4 or 2.5, which can reduce the field curvature and chromatic aberration of the viewing image of the optical system 100 .
  • the quality of the positive power lens 1 is greater than that of the negative power lens 2 .
  • the "quality" of the lens refers to the product of the material density of the lens and the volume of the lens. It can be understood that the optical system 100 of the present disclosure can be applied to a VR display device, and the viewer can wear the VR display device to watch, because the quality of the positive power lens 1 is greater than that of the negative power lens 2, and the positive power Compared with the negative power lens 2, the power lens 1 is closer to the human eye 4 of the viewer, so that the center of gravity of the VR display device is closer to the viewer, which can improve the wearing comfort of the viewer.
  • the material of positive refractive power lens 1 can comprise glass
  • the material of negative refractive power lens 2 can comprise plastics
  • the material density of glass is greater than the material density of plastics
  • the volume of positive refractive power lens 1 and negative refractive power The volume difference of lens 2 is small, so that the quality of lens 1 with positive power is greater than that of lens 2 with negative power.
  • the positive refractive power lens 1 and the negative refractive power lens 2 can also use Fresnel lenses, and the Fresnel lens has uniform light output and high light output efficiency, and the optical system 100 using this design has a brighter image. Uniform, and the thickness of the Fresnel lens is small, which is conducive to the thinning of the optical system 100 .
  • the display 3 can be a liquid crystal display (Liquid Crystal Display, LCD for short), an organic electroluminescent display (Organic Light-Emitting Diode, OLED for short) or a silicon-based liquid crystal display (Liquid Crystal Display). on Silicon, referred to as LCOS) and other displays, the display 3 is a micro-display, and its diagonal length ranges from 1.5inch to 2.5inch, for example, the diagonal length of the display 3 is 1.5inch, 1.8inch, 2inch, 2.3inch or 2.5 inch.
  • LCD liquid crystal Display
  • OLED Organic Light-Emitting Diode
  • LCOS silicon-based liquid crystal display
  • the refractive index of the positive refractive power lens 1 and the refractive index of the negative refractive power lens 2 are set such that the refractive index of one of them is greater than the refractive index of the other, and the larger refractive index
  • the first refractive index, the smaller refractive index is the second refractive index, the first refractive index is greater than 1.7, the second refractive index is greater than 1.5, and the ratio of the first refractive index to the second refractive index is less than or equal to 1.1, for example, the first The ratio of the first refractive index to the second refractive index is 1.01, 1.03, 1.05, 1.07 or 1.09.
  • the viewing angle of the viewing image of the optical system 100 can be further increased, making the optical system 100 thinner.
  • the first convex surface 11 and the second convex surface 12 of the positive refractive power lens 1 can both be aspherical
  • the third convex surface 21 and the fourth concave surface 22 of the negative refractive power lens 2 can be both Aspherical
  • the first convex surface 11, the second convex surface 12, the third convex surface 21 and the fourth concave surface 22 may all be even-order aspheric surfaces
  • the first convex surface 11, the second convex surface 12, the third convex surface 21 and the fourth concave surface 22 The surface equations of are the following formula (2):
  • Z is the vertical distance between the point E of the lens surface (the second convex surface 12) and the first reference plane N, and the distance between the first reference plane N and the lens surface Vertex P2 is tangent;
  • c is the curvature at the vertex P2 of the lens surface;
  • k is the quadric surface coefficient of the lens surface;
  • r is the vertical distance between the point E of the lens surface and the optical axis A;
  • a 2i is the polynomial coefficient; ⁇ 1 and is an integer.
  • f refers to the focal length of the optical system 100
  • TL refers to the length of the optical system 100
  • FOV Field of View
  • R refers to the lens The radius of curvature of the surface, where the radius of curvature is a positive number means that the center of the lens surface is located on the side of the surface close to the display 3, and the radius of curvature is negative means that the center of the lens surface is located on the side of the surface away from the display 3
  • T Refer to the distance between two adjacent lens surfaces, for example, with reference to Figure 5, along the optical axis A, the distance between the first convex surface 11 and the second convex surface 12 is 13mm, with reference to Figure 2, along the optical axis A, the first The distance between the second convex surface 12 and the third convex surface 21 is 0.5 mm.
  • the distance between the third convex surface 21 and the fourth concave surface 22 is 4 mm.
  • the distance between the fourth concave surface 22 and the surface 31 of the display 3 is 16.5 mm;
  • N refers to the refractive index of the lens;
  • V refers to the dispersion coefficient of the lens.
  • the refractive index of the positive power lens 1 is 1.76
  • the dispersion coefficient is 52.3
  • the refractive index of the negative power lens 2 is 1.64
  • the dispersion coefficient is 22.4.
  • the ratio of the refractive index of the positive power lens 1 to the negative power lens 2 is 1.07.
  • the first ratio of the dispersion coefficient to the refractive index of the positive power lens 1 is 29.72
  • the second ratio of the dispersion coefficient to the refractive index of the negative power lens 2 is 13.66
  • the ratio of the first ratio to the second ratio is 2.2.
  • the diagonal length of the display 3 is 2.1 inches
  • the pixel density of the display 3 is 1500, that is, the number of pixels per inch (Pixels per inch, PPI for short) of the display 3 is 1500.
  • FIG. 8 shows the spot diagram (OBJ) of the imaging spot of the optical system 100 at different viewing angles, wherein, when the viewing angle is 0°, the geometric spot radius is 32 ⁇ m. In the case of a viewing angle of 7.5°, the geometric spot radius is 79 ⁇ m. In the case of a viewing angle of 15°, the geometric spot radius is 132 ⁇ m. In the case of a viewing angle of 22.5°, the geometric spot radius is 79 ⁇ m. In the case of a viewing angle of 30°, the geometric spot radius is 125 ⁇ m. In the case of a viewing angle of 37.5°, the geometric spot radius is 141 ⁇ m. In the case of a viewing angle of 45°, the geometric spot radius is 157 ⁇ m. It can be seen that when the viewing angle is 45°, the geometric spot radius is the largest, so the root mean square radius is the largest, which is 64 ⁇ m.
  • Fig. 9 shows the field curvature diagram (Field Curvature) of this optical system 100
  • a plurality of solid lines in the field curvature diagram represent the field curvature of the light of different wavelengths in the meridian direction
  • a plurality of dotted lines represent the light of different wavelengths in the arc
  • the curvature of field in the sagittal direction shows that, when the viewing angle is in the range of 0° to 45°, the field curvature of the optical system 100 is less than 2.0mm.
  • FIG. 10 shows the distortion diagram ⁇ F-Tan(Theta)Distortion ⁇ of light of different wavelengths emitted by the optical system 100. It can be seen that the distortion of the optical system 100 is Less than 10%, for example, when the viewing angle is 45°, the distortion of the optical system 100 is the largest, and the distortion is 7%, and the maximum distortion of the optical system 100 is small, which proves that the aberration of the optical system 100 is small , Higher picture quality.
  • the optical system 100 further includes a fixed part 101 and a moving part 102 that are slidably connected, the positive power lens 1 and the negative power lens 2 are arranged on the fixed part 101, and the display 3 is set On the moving part 102 , the moving part 102 is configured to drive the display 3 to move along the optical axis A, so as to adjust the diopter of the optical system 100 .
  • the distance S1 between the optical center C2 of the negative power lens 2 and the center C3 of the display 3 is 16.5 mm.
  • the diopter of the optical system 100 is -1D.
  • the moving part 102 drives the display 3 to move towards the direction close to the negative power lens 2, and along the optical axis A, the distance between the optical center C2 of the negative power lens 2 and the center C3 of the display 3 is The distance S2 between them is 13.6mm, in this case, the diopter of the optical system 100 is -6D.
  • the diopter of the optical system 100 can be adjusted by driving the display 3 to move along the optical axis A through the moving part 102 , for example, the diopter of the optical system 100 can be continuously adjusted from -1D to -6D.
  • some embodiments of the present disclosure also provide a VR display device 200 , which may include the optical system 100 in the above embodiments.
  • the aforementioned VR display device 200 of the present disclosure has less aberration, less distortion, and higher picture quality when viewing images, which can bring a stronger sense of immersion to the viewer, and the VR display device 200 has a higher light extraction efficiency. , the field of view is large, the device is thin and comfortable to wear.

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Abstract

一种光学系统(100)，具有光轴(A)，光学系统(100)包括沿光轴(A)依次设置的正光焦度透镜(1)、负光焦度透镜(2)和显示器(3)。正光焦度透镜(1)包括远离显示器(3)的第一凸面(11)，及靠近显示器(3)的第二凸面(12)，第一凸面(11)和第二凸面(12)均相对于正光焦度透镜(1)的光心(C1)外凸。负光焦度透镜(2)包括远离显示器(3)的第三凸面(21)，及靠近显示器(3)的第四凹面(22)，第三凸面(21)相对于负光焦度透镜(2)的光心(C2)外凸，第四凹面(22)相对于负光焦度透镜(2)的光心(C2)内凹。其中，正光焦度透镜(1)的折射率和负光焦度透镜(2)的折射率中，其中一者的折射率大于另一者的折射率，较大的折射率为第一折射率，较小的折射率为第二折射率，第一折射率大于1.7，第二折射率大于1.5，且第一折射率与第二折射率的比值小于或等于2。

Description

光学系统及VR显示设备 技术领域
本公开涉及显示技术领域，尤其涉及一种光学系统及VR显示设备。
背景技术
虚拟现实(Virtual Reality，简称VR)技术是一项涉及众多学科领域的高新技术，它集计算机仿真、三维立体设计、图像处理、模式识别、微电子及并行处理技术为一体，利用虚拟现实硬件设备和计算机系统创建一个逼真虚拟环境。用户在虚拟空间体验与现实世界相同的感受，例如视觉、听觉、触觉、嗅觉、碰撞、移动和搬运动态交互感等。
目前，VR显示设备正朝着大视场角、轻薄化的方向发展，以给观看者带来更好的沉浸感，提升用户体验。
发明内容
一方面，提供一种光学系统，具有光轴。所述光学系统包括沿所述光轴依次设置的正光焦度透镜、负光焦度透镜和显示器。所述正光焦度透镜包括远离所述显示器的第一凸面，及靠近所述显示器的第二凸面，所述第一凸面和所述第二凸面均相对于所述正光焦度透镜的光心外凸。所述负光焦度透镜包括远离所述显示器的第三凸面，及靠近所述显示器的第四凹面，所述第三凸面相对于所述负光焦度透镜的光心外凸，所述第四凹面相对于所述负光焦度透镜的光心内凹。其中，所述正光焦度透镜的折射率和所述负光焦度透镜的折射率中，其中一者的折射率大于另一者的折射率，较大的折射率为第一折射率，较小的折射率为第二折射率，所述第一折射率大于1.7，所述第二折射率大于1.5，且所述第一折射率与所述第二折射率的比值小于或等于2。
在一些实施例中，所述负光焦度透镜的第四凹面的曲率半径，小于所述第三凸面的曲率半径。
在一些实施例中，所述第四凹面的曲率半径大于0，且小于或等于50mm；所述第三凸面的曲率半径大于0，且小于或等于100mm。
在一些实施例中，所述负光焦度透镜包括靠近所述光轴的中间部分，以及围绕所述中间部分的边缘部分。沿所述光轴，所述中间部分的厚度小于所述边缘部分的厚度。
在一些实施例中，所述第一折射率与所述第二折射率的比值小于或等于1.1。
在一些实施例中，所述正光焦度透镜的光焦度范围为0.05mm -1～0.15mm -1。 所述正光焦度透镜的折射率大于所述负光焦度透镜的折射率。
在一些实施例中，所述负光焦度透镜的光焦度范围为-0.1mm -1～-0.02mm -1。
在一些实施例中，所述第一折射率为N 1，所述第二折射率为N 2。沿所述光轴，所述正光焦度透镜的第二凸面，与所述负光焦度透镜的第三凸面之间的距离为D。其中，
Figure PCTCN2021133282-appb-000001
在一些实施例中，沿所述光轴，所述正光焦度透镜的第二凸面，与所述负光焦度透镜的第三凸面之间的距离范围为0.5mm～0.55mm。
在一些实施例中，沿所述光轴，所述正光焦度透镜的第一凸面的顶点，与所述显示器远离所述负光焦度透镜的表面的距离小于或等于35mm。
在一些实施例中，所述正光焦度透镜的折射率为N a，色散系数为V a。所述负光焦度透镜的折射率为N b，色散系数为V b。其中，
Figure PCTCN2021133282-appb-000002
和
Figure PCTCN2021133282-appb-000003
中一者大于另一者，较大一者与较小一者的比值小于或等于2.5。
在一些实施例中，所述第一凸面、所述第二凸面、所述第三凸面和所述第四凹面均为非球面。
在一些实施例中，所述第一凸面、所述第二凸面、所述第三凸面和所述第四凹面均为偶次非球面。所述第一凸面、所述第二凸面、所述第三凸面和所述第四凹面的面型方程均为
Figure PCTCN2021133282-appb-000004
其中，Z为透镜表面的点与第一参考面的垂直距离，所述第一参考面与透镜表面的顶点相切；c为透镜表面的顶点处的曲率；k为透镜表面的二次曲面系数；r为透镜表面的点与所述光轴的垂直距离；A 2i为多次项系数；i≥1，且为整数。
在一些实施例中，所述正光焦度透镜的材料包括玻璃，所述负光焦度透镜的材料包括塑料。
在一些实施例中，所述正光焦度透镜的质量大于所述负光焦度透镜的质量。
在一些实施例中，所述光学系统还包括固定件和移动件，所述正光焦度透镜和所述负光焦度透镜设置于所述固定件上。移动件与所述固定件滑动连接，所述显示器设置于所述移动件上，所述移动件被配置为带动所述显示器沿所述光轴移动。
另一方面，提供一种VR显示设备。所述VR显示设备包括：如上述任一实施例所述的光学系统。
附图说明
为了更清楚地说明本公开中的技术方案，下面将对本公开一些实施例中 所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本公开的一些实施例的附图，对于本领域普通技术人员来讲，还可以根据这些附图获得其他的附图。此外，以下描述中的附图可以视作示意图，并非对本公开实施例所涉及的产品的实际尺寸、方法的实际流程、信号的实际时序等的限制。
图1为根据一些实施例的光学系统的一种结构图；
图2为图1中的光学系统在M处的局部放大图；
图3为根据一些实施例的光学系统的光路图；
图4为根据一些实施例的光学系统的正光焦度透镜的结构图；
图5为图4中的正光焦度透镜沿剖面线A-A＇的剖面图；
图6为根据一些实施例的光学系统的负光焦度透镜的结构图；
图7为图6中的负光焦度透镜沿剖面线B-B＇的剖面图；
图8为根据一些实施例的光学系统的点列图；
图9为根据一些实施例的光学系统的场曲图；
图10为根据一些实施例的光学系统的畸变图；
图11为根据一些实施例的光学系统的另一种结构图；
图12为根据一些实施例的光学系统的又一种结构图；
图13为根据一些实施例的VR显示设备的结构图。
具体实施方式
下面将结合附图，对本公开一些实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本公开一部分实施例，而不是全部的实施例。基于本公开所提供的实施例，本领域普通技术人员所获得的所有其他实施例，都属于本公开保护的范围。
除非上下文另有要求，否则，在整个说明书和权利要求书中，术语“包括(comprise)”及其其他形式例如第三人称单数形式“包括(comprises)”和现在分词形式“包括(comprising)”被解释为开放、包含的意思，即为“包含，但不限于”。在说明书的描述中，术语“一个实施例(one embodiment)”、“一些实施例(some embodiments)”、“示例性实施例(exemplary embodiments)”、“示例(example)”、“特定示例(specific example)”或“一些示例(some examples)”等旨在表明与该实施例或示例相关的特定特征、结构、材料或特性包括在本公开的至少一个实施例或示例中。上述术语的示意性表示不一定是指同一实施例或示例。此外，所述的特定特征、结构、材料或特点可以以任何适当方式包括在任何一个或多个实施例或示例中。
以下，术语“第一”、“第二”仅用于描述目的，而不能理解为指示或暗示相对重要性或者隐含指明所指示的技术特征的数量。由此，限定有“第一”、“第二”的特征可以明示或者隐含地包括一个或者更多个该特征。在本公开实施例的描述中，除非另有说明，“多个”的含义是两个或两个以上。
在描述一些实施例时，可能使用了“连接”及其衍伸的表达。例如，描述一些实施例时可能使用了术语“连接”以表明两个或两个以上部件彼此间有直接物理接触或电接触。
本文中“被配置为”的使用意味着开放和包容性的语言，其不排除适用于或被配置为执行额外任务或步骤的设备。
另外，“基于”的使用意味着开放和包容性，因为“基于”一个或多个所述条件或值的过程、步骤、计算或其他动作在实践中可以基于额外条件或超出所述的值。
如本文所使用的那样，“垂直”包括所阐述的情况以及与所阐述的情况相近似的情况，该相近似的情况的范围处于可接受偏差范围内，其中所述可接受偏差范围如由本领域普通技术人员考虑到正在讨论的测量以及与特定量的测量相关的误差(即，测量系统的局限性)所确定。例如，“垂直”包括绝对垂直和近似垂直，其中近似垂直的可接受偏差范围例如也可以是5°以内偏差。
本文参照作为理想化示例性附图的剖视图和/或平面图描述了示例性实施方式。在附图中，为了清楚，放大了层和区域的厚度。因此，可设想到由于例如制造技术和/或公差引起的相对于附图的形状的变动。因此，示例性实施方式不应解释为局限于本文示出的区域的形状，而是包括因例如制造而引起的形状偏差。例如，示为矩形的蚀刻区域通常将具有弯曲的特征。因此，附图中所示的区域本质上是示意性的，且它们的形状并非旨在示出设备的区域的实际形状，并且并非旨在限制示例性实施方式的范围。
在相关技术中，VR显示设备包括折反式的薄饼(pancake)结构，采用这种结构设计可减小显示设备的厚度，但是，会导致显示设备的出光效率较低(出光效率不足25％)，且观看画面存在“鬼影”、视场角较小的问题，进而导致观看者的视觉体验较差。
为解决上述问题，如图1所示，本公开的一些实施例提供了一种光学系统100，光学系统100具有光轴A，光轴A即为光学系统100的对称轴，
如图1所示，光学系统100包括沿光轴A依次设置的正光焦度透镜1、负光焦度透镜2和显示器3，并且，正光焦度透镜1的光心C1、负光焦度透 镜2的光心C2以及显示器3的中心C3均位于光轴A上。
需要说明的是，“正光焦度透镜1”的光焦度大于0，光线经正光焦度透镜1的折射后汇聚。“负光焦度透镜2”的光焦度小于0，光线经负光焦度透镜2的折射后发散。
如图1所示，正光焦度透镜1包括远离显示器3的第一凸面11，及靠近显示器3的第二凸面12，第一凸面11和第二凸面12均相对于正光焦度透镜1的光心C1外凸。
如图1所示，负光焦度透镜2包括远离显示器3的第三凸面21，及靠近显示器3的第四凹面22，第三凸面21相对于负光焦度透镜2的光心C2外凸，第四凹面22相对于负光焦度透镜2的光心C2内凹。
其中，正光焦度透镜1的折射率和负光焦度透镜2的折射率中，其中一者的折射率大于另一者的折射率，为方便描述，将较大的折射率称为“第一折射率”，将较小的折射率称为“第二折射率”，第一折射率大于1.7，第二折射率大于1.5，且第一折射率与第二折射率的比值小于或等于2。
示例性地，光学系统100的焦距范围为20mm～35mm，例如，光学系统100的焦距为20mm、25mm、28mm、30mm或35mm。
本公开的上述实施例中，结合图1和图3，光学系统100采用正光焦度透镜1与负光焦度透镜2结合的结构设计，可减小该光学系统100的观看画面(光学系统100在人眼4处的成像)的球差、场曲等像差，减少光学系统100出光中的杂散光线，以改善画面的“鬼影”和眩光问题，提高画面质量，从而增强观看者的沉浸感，并且，光学系统100的出光效率较高。
其中，负光焦度透镜2的第四凹面22相对于负光焦度透镜2的光心C2内凹，以便于收集显示器3所发出的角度较大的光线。并且，正光焦度透镜1的折射率和负光焦度透镜2的折射率设置为，其中一者的折射率大于另一者的折射率，较大的折射率为第一折射率，较小的折射率为第二折射率，第一折射率大于1.7，第二折射率大于1.5，且第一折射率与第二折射率的比值小于或等于2，采用这种设计，正光焦度透镜1和负光焦度透镜2可在较短的距离(光学系统100的焦距)内将角度较大的光线折射入人眼4，从而可增大该光学系统100的观看画面的视场角(例如，视场角大于或等于90°)，且可以使光学系统100轻薄化。
下面结合附图，分别对光学系统100中的正光焦度透镜1、负光焦度透镜2和显示器3，以及三者之间的关联进行解释说明。
在一些实施例中，如图4和图5所示，正光焦度透镜1的光焦度大于0， 正光焦度透镜1的光焦度范围为0.05mm -1～0.15mm -1，例如，正光焦度透镜1的光焦度为0.05mm -1、0.07mm -1、0.1mm -1、0.12mm -1或0.15mm -1。
在一些实施例中，如图4和图5所示，正光焦度透镜1的第一凸面11可以为球面或非球面，第二凸面12可以为球面或非球面。
需要说明的是，“球面”是指该透镜表面上各处的曲率半径不变。以第一凸面11为例，“非球面”是指该透镜表面从顶点P1到边缘，透镜表面的曲率半径逐渐增加(透镜表面逐渐平坦)。
示例性地，正光焦度透镜1的第一凸面11和第二凸面12均为非球面，可减小该光学系统100的观看画面的球差、彗差、场曲等多种像差。
在一些实施例中，如图4和图5所示，正光焦度透镜1的第一凸面11的曲率半径大于0，且小于或等于100mm，例如，第一凸面11的曲率半径为20mm、40mm、60mm、80mm或100mm。第二凸面12的曲率半径大于0，且小于或等于50mm，例如，第二凸面12的曲率半径为10mm、20mm、30mm、40mm或50mm。
在一些实施例中，如图4和图5所示，正光焦度透镜1包括靠近光轴A的中间部分a1，以及围绕中间部分a1的边缘部分b1。沿光轴A，中间部分a1的厚度大于边缘部分b1的厚度，即正光焦度透镜1的中间部分a1较厚，边缘部分b1较薄。
在一些实施例中，如图4和图5所示，正光焦度透镜1的材料可包括玻璃或塑料。
在一些实施例中，如图6和图7所示，负光焦度透镜2的光焦度小于0，负光焦度透镜2的光焦度范围为-0.1mm -1～-0.02mm -1，例如，负光焦度透镜2的光焦度为-0.1mm -1、-0.08mm -1、-0.06mm -1、-0.04mm -1或-0.02mm -1。
在一些实施例中，如图6和图7所示，负光焦度透镜2的第三凸面21可以为球面或非球面，第四凹面22可以为球面或非球面。
示例性地，负光焦度透镜2的第三凸面21和第四凹面22均为非球面，可减小该光学系统100的观看画面的球差、彗差、场曲等多种像差。
在一些实施例中，如图6和图7所示，负光焦度透镜2的第四凹面22的曲率半径，小于第三凸面21的曲率半径。
可以理解的是，负光焦度透镜2的第四凹面22相对于负光焦度透镜2的光心C2内凹，并且相较于第三凸面21的曲率半径，第四凹面22的曲率半径设置的较小，即第四凹面22比第三凸面21更加弯曲，更有利于第四凹面22收集显示器3所发出的角度较大的光线，从而有利于增大该光学系统100的 观看画面的视场角。
示例性地，如图6和图7所示，负光焦度透镜2的第三凸面21的曲率半径大于0，且小于或等于100mm，例如，第三凸面21的曲率半径为20mm、40mm、60mm、80mm或100mm。第四凹面22的曲率半径大于0，且小于或等于50mm，例如，第四凹面22的曲率半径为10mm、20mm、30mm、40mm或50mm。
在一些实施例中，如图6和图7所示，负光焦度透镜2包括靠近光轴A的中间部分a2，以及围绕中间部分a2的边缘部分b2。沿光轴A，中间部分a2的厚度小于边缘部分b2的厚度，使负光焦度透镜2的中间部分a2较薄，边缘部分b2较厚。
在相关技术中，负光焦度透镜的两侧表面均相对于光心内凹，即负光焦度透镜的两侧表面均为凹面，使得负光焦度透镜的中间部分非常薄，边缘部分与中间部分的厚度差较大，导致负光焦度透镜的结构强度较低，负光焦度透镜容易破碎。
而本公开的一些实施例，如图6和图7所示，负光焦度透镜2的第三凸面21相对于负光焦度透镜2的光心C2外凸，可增大负光焦度透镜2的中间部分a2的厚度，提高负光焦度透镜2的中间部分a2的结构强度，避免了负光焦度透镜2的中间部分a2过薄而易破碎的问题。
在一些实施例中，如图6和图7所示，负光焦度透镜2的材料可包括玻璃或塑料。
在一些实施例中，如图1和图3所示，正光焦度透镜1的折射率大于负光焦度透镜2的折射率，即正光焦度透镜1的折射率大于1.7，负光焦度透镜2的折射率大于1.5。并且，正光焦度透镜1的光焦度范围为0.05mm -1～0.15mm -1，正光焦度透镜1的光焦度较小，使得正光焦度透镜1可将角度较大的光线折射入人眼4。在此基础上，正光焦度透镜1与负光焦度透镜2配合使用，可增大该光学系统100的观看画面的视场角。
在一些实施例中，如图1和图2所示，正光焦度透镜1的折射率和负光焦度透镜2的折射率中，较大的第一折射率设为N 1，较小的第二折射率设为N 2。沿光轴A，正光焦度透镜1的第二凸面12，与负光焦度透镜2的第三凸面21之间的距离设为D。
其中，第一折射率N 1、第二折射率N 2和距离D之间的关系满足下列公式(1)：
Figure PCTCN2021133282-appb-000005
可见，根据正光焦度透镜1的折射率和负光焦度透镜2的折射率的设计值，可确定上述距离D的合理取值范围，在距离D处于合理取值范围内的情况下，保证光学系统100的长度不会过长，并且，保证正光焦度透镜1与负光焦度透镜2之间装配的可靠性。
需要说明的是，参考图1，“光学系统100的长度”是指沿光轴A，正光焦度透镜1的第一凸面11的顶点P1，与显示器3远离负光焦度透镜2的表面31的距离。
示例性地，沿光轴A，正光焦度透镜1的第二凸面12，与负光焦度透镜2的第三凸面21之间的距离D范围为0.5mm～0.55mm，例如，距离D可为0.51mm、0.52mm、0.53mm、0.54mm或0.55mm。
可以理解的是，若距离D小于0.5mm，说明第二凸面12与第三凸面21之间的距离过小，即正光焦度透镜1与负光焦度透镜2之间的间距过小，这可能导致正光焦度透镜1与负光焦度透镜2之间的装配困难。若距离D大于0.55mm，说明第二凸面12与第三凸面21之间的距离过大，即正光焦度透镜1与负光焦度透镜2之间的间距过大，这可能导致光学系统100的长度过长，不利于光学系统100的轻薄化。
在一些实施例中，如图1所示，沿光轴A，正光焦度透镜1的第一凸面11的顶点P1，与显示器3远离负光焦度透镜2的表面31的距离小于或等于35mm，即光学系统100的长度小于或等于35mm。例如，光学系统100的长度为31mm、32mm、33mm、34mm或35mm。
在一些实施例中，如图1所示，正光焦度透镜1的折射率设为N a，色散系数设为V a。负光焦度透镜2的折射率设为N b，色散系数设为V b。其中，
Figure PCTCN2021133282-appb-000006
和
Figure PCTCN2021133282-appb-000007
中一者大于另一者，较大一者与较小一者的比值小于或等于2.5，例如，
Figure PCTCN2021133282-appb-000008
和
Figure PCTCN2021133282-appb-000009
中较大一者与较小一者的比值为2.1、2.2、2.3、2.4或2.5，可减小该光学系统100的观看画面的场曲和色差。
在一些实施例中，如图1和图3所示，正光焦度透镜1的质量大于负光焦度透镜2的质量。需要说明的是，透镜的“质量”是指透镜的材料密度与透镜的体积的乘积。可以理解的是，本公开的光学系统100可应用于VR显示设备，观看者可佩戴该VR显示设备进行观看，由于正光焦度透镜1的质量大于负光焦度透镜2的质量，且正光焦度透镜1相较于负光焦度透镜2更靠近 观看者的人眼4，使得VR显示设备的重心更靠近观看者，可提高观看者的佩戴舒适性。
示例性地，正光焦度透镜1的材料可包括玻璃，负光焦度透镜2的材料可包括塑料，玻璃的材料密度大于塑料的材料密度，且正光焦度透镜1的体积与负光焦度透镜2的体积差异较小，使得正光焦度透镜1的质量大于负光焦度透镜2的质量。
在一些实施例中，正光焦度透镜1和负光焦度透镜2还可采用菲涅尔透镜，菲涅尔透镜的出光均匀且出光效率较高，采用此设计的光学系统100的画面亮度更均匀，并且，菲涅尔透镜的厚度小，有利于光学系统100的轻薄化。
在一些实施例中，如图1所示，显示器3可以是液晶显示器(Liquid Crystal Display，简称LCD)、有机电致发光显示器(Organic Light-Emitting Diode，简称OLED)或硅基液晶显示器(Liquid Crystal on Silicon，简称LCOS)等显示器，显示器3为微型显示器，其对角线长度范围为1.5inch～2.5inch，例如，显示器3的对角线长度为1.5inch、1.8inch、2inch、2.3inch或2.5inch。
经本公开的发明人研究发现，正光焦度透镜1的折射率和负光焦度透镜2的折射率设置为，其中一者的折射率大于另一者的折射率，较大的折射率为第一折射率，较小的折射率为第二折射率，第一折射率大于1.7，第二折射率大于1.5，且第一折射率与第二折射率的比值小于或等于1.1，例如，第一折射率与第二折射率的比值为1.01、1.03、1.05、1.07或1.09，在此情况下，可进一步增大该光学系统100的观看画面的视场角，使光学系统100更轻薄化。
前文提到，如图1所示，正光焦度透镜1的第一凸面11和第二凸面12可均为非球面，负光焦度透镜2的第三凸面21和第四凹面22可均为非球面。示例性地，第一凸面11、第二凸面12、第三凸面21和第四凹面22可均为偶次非球面，第一凸面11、第二凸面12、第三凸面21和第四凹面22的面型方程均为如下公式(2)：
Figure PCTCN2021133282-appb-000010
参考图5，以第二凸面12为例，公式(2)中，Z为透镜表面(第二凸面12)的点E与第一参考面N的垂直距离，第一参考面N与透镜表面的顶点P2相切；c为透镜表面的顶点P2处的曲率；k为透镜表面的二次曲面系数；r为透镜表面的点E与光轴A的垂直距离；A 2i为多次项系数；i≥1，且为整数。
基于此，发明人设计实验进行验证，光学系统100的各参数的具体数值可参见如下表1和表2：
Figure PCTCN2021133282-appb-000011
表1
表1中，“f”是指光学系统100的焦距；“TL”是指光学系统100的长度；“FOV(Field of View)”是指光学系统100的视场角；“R”是指透镜表面的曲率半径，其中，曲率半径为正数是指透镜表面的圆心位于该表面靠近显示器3的一侧，曲率半径为负数是指透镜表面的圆心位于该表面远离显示器3的一侧；“T”是指相邻的两个透镜表面的距离，例如，参考图5，沿光轴A，第一凸面11与第二凸面12之间的距离为13mm，参考图2，沿光轴A，第二凸面12与第三凸面21之间的距离为0.5mm，参考图7，沿光轴A，第三凸面21与第四凹面22之间的距离为4mm，参考图1，沿光轴A，第四凹面22与显示器3的表面31之间的距离为16.5mm；“N”是指透镜的折射率；“V”是指透镜的色散系数。
其中，正光焦度透镜1的折射率为1.76，色散系数为52.3，负光焦度透镜2的折射率为1.64，色散系数为22.4。正光焦度透镜1的折射率与负光焦度透镜2的折射率的比值为1.07。正光焦度透镜1的色散系数与折射率的第一比值为29.72，负光焦度透镜2的色散系数与折射率的第二比值为13.66，第一比值与第二比值的比值为2.2。
Figure PCTCN2021133282-appb-000012
表2
此外，如图1所示，显示器3的对角线长度为2.1inch，显示器3的像素密度为1500，即显示器3的每英寸的像素数(Pixels per inch，简称PPI)为1500。
实验结果可参考图8～图10，图8示出了该光学系统100在不同视角下成像光斑的点列图(OBJ)，其中，在视角为0°的情况下，几何光斑半径为32μm。在视角为7.5°的情况下，几何光斑半径为79μm。在视角为15°的情况下，几何光斑半径为132μm。在视角为22.5°的情况下，几何光斑半径为79μm。在视角为30°的情况下，几何光斑半径为125μm。在视角为37.5°的情况下，几何光斑半径为141μm。在视角为45°的情况下，几何光斑半径为157μm。可见，在视角为45°的情况下，几何光斑半径最大，因此，其均方根半径最大，为64μm。
图9示出了该光学系统100的场曲图(Field Curvature)，场曲图中的多条实线表示不同波长的光在子午方向上的场曲，多条虚线表示不同波长的光在弧矢方向上的场曲，可见，在视角处于0～45°范围内的情况下，光学系统100的场曲小于2.0mm。
图10示出了该光学系统100所发出的不同波长的光的畸变图{F-Tan(Theta)Distortion}，可见，在视角处于0～45°范围内的情况下，光学系统100的畸变量小于10％，例如，在视角为45°的情况下，光学系统100的畸变量最大，畸变量为7％，该光学系统100的最大畸变量较小，证明该光学系统100的像差较小、画面质量较高。
在一些实施例中，如图11所示，光学系统100还包括滑动连接的固定件101和移动件102，正光焦度透镜1和负光焦度透镜2设置于固定件101上，显示器3设置于移动件102上，移动件102被配置为带动显示器3沿光轴A移动，可调节该光学系统100的屈光度。
示例性地，如图11所示，沿光轴A，负光焦度透镜2的光心C2与显示器3的中心C3之间的距离S1为16.5mm，在此情况下，光学系统100的屈光度为-1D。
示例性地，如图12所示，移动件102带动显示器3朝靠近负光焦度透镜2的方向移动，沿光轴A，负光焦度透镜2的光心C2与显示器3的中心C3之间的距离S2为13.6mm，在此情况下，光学系统100的屈光度为-6D。
通过上述设计，通过移动件102带动显示器3沿光轴A移动，可调节该光学系统100的屈光度，例如，可实现该光学系统100的屈光度从-1D至-6D的连续调节。
如图13所示，本公开的一些实施例还提供了一种VR显示设备200，该VR显示设备200可包括如上述实施例中的光学系统100。
本公开的上述VR显示设备200，其观看画面的像差较小、畸变量较小、画面质量较高，可以带给观看者较强的沉浸感，并且，VR显示设备200的出光效率较高，视场角较大，设备轻薄且佩戴舒适。
以上所述，仅为本公开的具体实施方式，但本公开的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本公开揭露的技术范围内，想到变化或替换，都应涵盖在本公开的保护范围之内。因此，本公开的保护范围应以所述权利要求的保护范围为准。

Claims (17)

  1. 一种光学系统，具有光轴，所述光学系统包括沿所述光轴依次设置的正光焦度透镜、负光焦度透镜和显示器；
    所述正光焦度透镜包括远离所述显示器的第一凸面，及靠近所述显示器的第二凸面，所述第一凸面和所述第二凸面均相对于所述正光焦度透镜的光心外凸；所述负光焦度透镜包括远离所述显示器的第三凸面，及靠近所述显示器的第四凹面，所述第三凸面相对于所述负光焦度透镜的光心外凸，所述第四凹面相对于所述负光焦度透镜的光心内凹；
    其中，所述正光焦度透镜的折射率和所述负光焦度透镜的折射率中，其中一者的折射率大于另一者的折射率，较大的折射率为第一折射率，较小的折射率为第二折射率，所述第一折射率大于1.7，所述第二折射率大于1.5，且所述第一折射率与所述第二折射率的比值小于或等于2。
  2. 根据权利要求1所述的光学系统，其中，所述负光焦度透镜的第四凹面的曲率半径，小于所述第三凸面的曲率半径。
  3. 根据权利要求1或2所述的光学系统，其中，所述第四凹面的曲率半径大于0，且小于或等于50mm；所述第三凸面的曲率半径大于0，且小于或等于100mm。
  4. 根据权利要求1～3中任一项所述的光学系统，其中，所述负光焦度透镜包括靠近所述光轴的中间部分，以及围绕所述中间部分的边缘部分；
    沿所述光轴，所述中间部分的厚度小于所述边缘部分的厚度。
  5. 根据权利要求1～4中任一项所述的光学系统，其中，所述第一折射率与所述第二折射率的比值小于或等于1.1。
  6. 根据权利要求1～5中任一项所述的光学系统，其中，所述正光焦度透镜的光焦度范围为0.05mm -1～0.15mm -1；
    所述正光焦度透镜的折射率大于所述负光焦度透镜的折射率。
  7. 根据权利要求6所述的光学系统，其中，所述负光焦度透镜的光焦度范围为-0.1mm -1～-0.02mm -1。
  8. 根据权利要求1～7中任一项所述的光学系统，其中，所述第一折射率为N 1，所述第二折射率为N 2；
    沿所述光轴，所述正光焦度透镜的第二凸面，与所述负光焦度透镜的第三凸面之间的距离为D；
    其中，
    Figure PCTCN2021133282-appb-100001
  9. 根据权利要求8所述的光学系统，其中，沿所述光轴，所述正光焦度 透镜的第二凸面，与所述负光焦度透镜的第三凸面之间的距离范围为0.5mm～0.55mm。
  10. 根据权利要求8或9所述的光学系统，其中，沿所述光轴，所述正光焦度透镜的第一凸面的顶点，与所述显示器远离所述负光焦度透镜的表面的距离小于或等于35mm。
  11. 根据权利要求1～10中任一项所述的光学系统，其中，所述正光焦度透镜的折射率为N a，色散系数为V a；
    所述负光焦度透镜的折射率为N b，色散系数为V b；
    其中，
    Figure PCTCN2021133282-appb-100002
    和
    Figure PCTCN2021133282-appb-100003
    中一者大于另一者，较大一者与较小一者的比值小于或等于2.5。
  12. 根据权利要求1～11中任一项所述的光学系统，其中，所述第一凸面、所述第二凸面、所述第三凸面和所述第四凹面均为非球面。
  13. 根据权利要求12所述的光学系统，其中，所述第一凸面、所述第二凸面、所述第三凸面和所述第四凹面均为偶次非球面；
    所述第一凸面、所述第二凸面、所述第三凸面和所述第四凹面的面型方程均为
    Figure PCTCN2021133282-appb-100004
    其中，Z为透镜表面的点与第一参考面的垂直距离，所述第一参考面与透镜表面的顶点相切；c为透镜表面的顶点处的曲率；k为透镜表面的二次曲面系数；r为透镜表面的点与所述光轴的垂直距离；A 2i为多次项系数；i≥1，且为整数。
  14. 根据权利要求1～13中任一项所述的光学系统，其中，所述正光焦度透镜的材料包括玻璃，所述负光焦度透镜的材料包括塑料。
  15. 根据权利要求1～14中任一项所述的光学系统，其中，所述正光焦度透镜的质量大于所述负光焦度透镜的质量。
  16. 根据权利要求1～15中任一项所述的光学系统，还包括：
    固定件；所述正光焦度透镜和所述负光焦度透镜设置于所述固定件上；
    移动件，与所述固定件滑动连接；所述显示器设置于所述移动件上，所述移动件被配置为带动所述显示器沿所述光轴移动。
  17. 一种VR显示设备，包括：如权利要求1～16中任一项所述的光学系统。
PCT/CN2021/133282 2021-11-25 2021-11-25 光学系统及vr显示设备 WO2023092421A1 (zh)

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