WO2020173180A1 - 近眼显示装置 - Google Patents

近眼显示装置 Download PDF

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Publication number
WO2020173180A1
WO2020173180A1 PCT/CN2019/125187 CN2019125187W WO2020173180A1 WO 2020173180 A1 WO2020173180 A1 WO 2020173180A1 CN 2019125187 W CN2019125187 W CN 2019125187W WO 2020173180 A1 WO2020173180 A1 WO 2020173180A1
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WIPO (PCT)
Prior art keywords
lens
display device
transflective element
lens surface
eye display
Prior art date
Application number
PCT/CN2019/125187
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English (en)
French (fr)
Inventor
董瑞君
刘亚丽
王晨如
栗可
张�浩
Original Assignee
京东方科技集团股份有限公司
北京京东方光电科技有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Application filed by 京东方科技集团股份有限公司, 北京京东方光电科技有限公司 filed Critical 京东方科技集团股份有限公司
Priority to US16/766,464 priority Critical patent/US11592671B2/en
Publication of WO2020173180A1 publication Critical patent/WO2020173180A1/zh
Priority to US17/992,416 priority patent/US20230084364A1/en

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    • 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
    • G02B27/017—Head mounted
    • G02B27/0172—Head mounted characterised by optical features
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B13/00—Optical objectives specially designed for the purposes specified below
    • G02B13/001—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras
    • G02B13/0015—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design
    • G02B13/002—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design having at least one aspherical surface
    • 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
    • G02B27/017—Head mounted
    • G02B2027/0178—Eyeglass type
    • 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
    • G02B27/10—Beam splitting or combining systems
    • G02B27/12—Beam splitting or combining systems operating by refraction only
    • G02B27/126—The splitting element being a prism or prismatic array, including systems based on total internal reflection
    • 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
    • G02B27/10—Beam splitting or combining systems
    • G02B27/14—Beam splitting or combining systems operating by reflection only
    • 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
    • G02B27/28—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising
    • G02B27/283—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising used for beam splitting or combining
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B3/00—Simple or compound lenses
    • G02B3/02—Simple or compound lenses with non-spherical faces
    • G02B3/04—Simple or compound lenses with non-spherical faces with continuous faces that are rotationally symmetrical but deviate from a true sphere, e.g. so called "aspheric" lenses

Definitions

  • the embodiment of the present disclosure relates to a near-eye display device.
  • the augmented reality (Augmented Reality, AR) display device can realize the fusion of the external real scene and the virtual scene by superimposing the virtual scene image displayed by the AR display device on the external real scene. Therefore, the augmented reality display device can improve the user's cognition of the real world, thereby improving the user's experience.
  • AR Augmented Reality
  • At least one embodiment of the present disclosure provides a near-eye display device that includes a lens and an optical path folding component.
  • the lens is configured to receive the projection light of the first image projected by the microdisplay, and to shape the first image;
  • the lens includes a main optical axis and is positioned in a first direction where the main optical axis of the lens is located Opposing first lens surface and second lens surface, the first lens surface and the second lens surface are both aspherical;
  • the optical path folding assembly is configured to receive the first lens shaped by the lens Light rays of an image, and folded light paths from the lens to the exit pupil of the near-eye display device.
  • the optical path folding assembly includes a first transflective element and a second transflective element that are opposed in a second direction crossing the first direction, and The light of the first image is sequentially reflected by the first transflective element, reflected by the second transflective element, and transmitted by the first transflective element.
  • the first transflective element is a specular transflective element.
  • the second transflective element is a curved transflective element
  • the curved surface of the second transflective element toward the exit pupil of the near-eye display device is a concave curved surface
  • the main optical axis of the second transflective element is parallel to the second direction; the main optical axis of the lens and the main optical axis of the second transflective element The optical axis intersects on the specular reflection surface of the first transflective element; the included angle between the specular reflection surface of the first transflective element and the first direction is equal to 45 degrees.
  • the first transflective element is a polarization splitting element.
  • the near-eye display device further includes a quarter-wave plate disposed on the first transflective element and the first transflective element in the second direction. Between the second transflective elements, and the light of the first image is sequentially reflected by the first transflective element, transmitted by the quarter wave plate, reflected by the second transflective element, and The quarter wave plate is transmitted and transmitted by the first transflective element.
  • the first direction is perpendicular to the second direction
  • the second direction is perpendicular to the quarter wave plate
  • the intersection of the extension line of the first transflective element and the extension line of the second transflective element is located on the plane where the quarter wave plate is located.
  • the near-eye display device further includes a polarizer, which is located on the light entrance side or the light exit side of the lens in the first direction.
  • the polarizer is configured such that the polarized light emitted from the polarizer is s-polarized light; and the polarization splitting element is configured to reflect the s-polarized light.
  • the reflectance of the first transflective element and the second transflective element are both greater than or equal to 50%.
  • the first lens surface is closer to the micro display than the second lens surface; and the radius of curvature of the first lens surface is larger than the The radius of curvature of the second lens surface.
  • the first lens surface and the second lens surface are both even-order aspheric surfaces; the surface shape z of the first lens surface of the lens satisfies the following expression Formula (1), the surface shape z of the second lens surface of the lens satisfies the following expression (2):
  • a11, a12, a13, a14, and a15 respectively satisfy the following ranges:
  • a21, a22, a23, a24 and a25 meet the following ranges:
  • the near-eye display device further includes a microdisplay configured to project the projection light of the first image toward the lens.
  • FIG. 1 is a schematic structural diagram of a near-eye display device provided by at least one embodiment of the present disclosure
  • FIG. 2 is a schematic diagram of the optical path of the near-eye display device shown in FIG. 1;
  • Figure 3 is an aspheric lens
  • FIGS. 1 and 2 are schematic diagrams of field curvature and distortion of the near-eye display device shown in FIGS. 1 and 2;
  • FIGS. 1 and 2 are schematic diagrams of a modulation transfer function curve of the near-eye display device shown in FIGS. 1 and 2;
  • FIG. 6 is a schematic structural diagram of another near-eye display device provided by at least one embodiment of the present disclosure.
  • FIG. 7 is another schematic diagram of another structure of another near-eye display device provided by at least one embodiment of the present disclosure.
  • Fig. 8 is a binocular virtual reality glasses provided by at least one embodiment of the present disclosure.
  • the inventor of the present disclosure noticed that the current augmented reality near-eye display device has a relatively large size and weight, low light utilization efficiency (that is, high power consumption), and a small field of view (FOV). This goes against the requirements and expectations of consumers for near-eye display devices, and makes it difficult for consumers to wear near-eye display devices in their daily lives.
  • At least one embodiment of the present disclosure provides a near-eye display device that includes a lens and an optical path folding assembly.
  • the lens is configured to receive the projection light of the first image projected by the microdisplay, and to shape the first image;
  • the lens includes a main optical axis, and a first lens surface opposed to the main optical axis of the lens in a first direction.
  • the second lens surface, the first lens surface and the second lens surface are aspherical surfaces;
  • the optical path folding component is configured to receive the light rays of the first image shaped by the lens, and to fold the optical path from the lens to the exit pupil of the near-eye display device .
  • the exit pupil of the near-eye display device is an image formed by the aperture stop of the near-eye display device in the image space of the near-eye display device.
  • the aperture stop of the near-eye display device refers to the effective aperture in the near-eye display device that limits the emitted light beam.
  • the position (represented by the exit pupil distance) and the diameter (represented by the exit pupil diameter) of the exit pupil represent the position and aperture of the exit beam.
  • the pupil of the user may be located at the exit pupil of the near-eye display device, so that the user can observe the entire field of view of the near-eye display device.
  • the exit pupil of the near-eye display device and the aperture stop of the near-eye display device coincide with each other.
  • the radius of curvature from the center of the first lens surface to the radius of curvature from the edge of the first lens surface is a non-constant value (for example, continuously changing).
  • the radius of curvature of the center of the first lens surface is smaller than the radius of curvature of the edge of the first lens surface;
  • the radius of curvature from the center of the second lens surface to the radius of curvature of the edge of the second lens surface is a non-constant value (for example, continuously changing ).
  • the radius of curvature of the center of the second lens surface is smaller than the radius of curvature of the edge of the second lens surface.
  • the imaging quality of the near-eye display device can be reduced, and the thickness of the near-eye display device can be reduced.
  • the volume of the near-eye display device can be reduced as much as possible, thereby improving the user experience.
  • FIG. 1 is a schematic structural diagram of a near-eye display device 100 provided by at least one embodiment of the present disclosure
  • FIG. 2 is a schematic diagram of an optical path of the near-eye display device 100 shown in FIG. 1. It should be noted that FIG. 2 shows that the near-eye display device 100 is a graph drawn on an equal scale based on the scale bar at the bottom of FIG. 2; for convenience of description, FIG. 2 also shows a microdisplay 140.
  • the near-eye display device 100 shown in FIGS. 1 and 2 may be implemented as monocular virtual reality glasses or binocular virtual reality glasses.
  • the near-eye display device 100 shown in FIGS. 1 and 2 may also be implemented as a virtual reality helmet or other Applicable virtual reality display device.
  • the near-eye display device 100 includes a lens 110 and an optical path folding assembly 120.
  • the near-eye display device 100 further includes a micro display 140.
  • the combined structure of the lens 110 and the optical path folding component 120 may be referred to as a reentrant optical system.
  • the microdisplay refers to a display whose diagonal length is less than 2 inches (about 5 cm).
  • the size of the micro display 140 provided by at least one embodiment of the present disclosure is between 0.5 inches and 1 inch, and the size of the micro display 140 is, for example, 0.7 inches or 0.8 inches.
  • the microdisplay 140 may be based on micro OLED (micro organic light emitting diode) technology, MicroLED (micro light emitting diode) technology, holographic display technology, liquid crystal on silicon (LCoS) technology, digital light processing (DLP) technology, or other applicable Technology realization of micro display device.
  • micro OLED micro organic light emitting diode
  • MicroLED micro light emitting diode
  • holographic display technology liquid crystal on silicon (LCoS) technology
  • LCDoS liquid crystal on silicon
  • DLP digital light processing
  • the microdisplay 140 is configured to project the projection light of the first image toward the lens 110.
  • the image displayed by the microdisplay 140 is regarded as the "object" of the near-eye display device 100, and the image displayed by the microdisplay 140 is located in the same plane, that is, the radius of curvature of the "object" of the near-eye display device 100 is infinite.
  • the size of the image displayed by the microdisplay 140 (the diagonal length of the image displayed by the microdisplay 140) is 17.682 mm.
  • the lens 110 is configured to receive the projection light of the first image projected by the microdisplay 140, and to shape the first image (for example, enlarge the first image), thereby obtaining a folding assembly suitable for passing through the subsequent optical path. 120
  • the lens 110 is configured to magnify the first image to an image suitable for human eyes; in other examples, the lens 110 and the optical path folding assembly 120 cooperate with each other to magnify the first image to be suitable for human eyes.
  • An image (or an image for display); in still other examples, the lens 110 is also configured to adjust the shape of the first image to an image suitable for human eyes to observe, thereby reducing image distortion.
  • the aforementioned image suitable for observation by the human eye (or image for display) has less distortion (for example, no distortion).
  • the lens 110 includes a main optical axis (not shown in the figure), and a first lens surface 111 and a second lens surface that are opposed to each other in a first direction D1 where the main optical axis of the lens 110 is located. 112.
  • the first lens surface 111 is closer to the micro display 140.
  • the main optical axis of the lens 110 refers to a straight line (virtual straight line) passing through the center (spherical center) of the first lens surface 111 and the center (spherical center) of the second lens surface 112.
  • the first lens surface 111 and the second lens surface 112 are both aspherical surfaces, that is, the lens 110 provided by at least one embodiment of the present disclosure is a double aspherical lens.
  • the aspherical surfaces of the first lens surface 111 and the second lens surface 112 are selected to reshape (for example, enlarge) the first image to obtain a display image suitable for being presented to the user by the subsequent optical path folding assembly 120, and is similar
  • the imaging quality of the near-eye display device can be reduced, and the thickness of the near-eye display device can be reduced.
  • the lens 110 by making the lens 110 a double aspheric lens, it is possible to improve the imaging quality of the near-eye display device 100 without using a free-form surface lens (or other lenses with advanced curved surfaces), thereby reducing the manufacturing of the lens 110 Difficulty and manufacturing cost.
  • the first lens surface 111 and the second lens surface 112 are convex curved surfaces that are convex in opposite directions, so the lens 110 is a convex lens (for example, a biconvex lens).
  • the first lens surface 111 is a convex curved surface that protrudes toward the micro display 140
  • the second lens surface 112 is a convex curved surface that protrudes away from the micro display 140.
  • the volume of the near-eye display device 100 can be reduced by optimizing the optical path folding assembly 120, thereby improving the user experience.
  • the specific structure and parameters of the lens 110 are exemplified below.
  • the first lens surface 111 is an even-order aspheric surface.
  • the surface shape of the first lens surface 111 of the lens 110 satisfies the following expression:
  • the second lens surface 112 is an even-order aspheric surface.
  • the surface shape z2 of the second lens surface 112 of the lens 110 satisfies the following expression:
  • a11, a12, a13, a14, and a15 meet the following ranges:
  • a21, a22, a23, a24, and a25 meet the following ranges:
  • a11, a12, a13, a14, a15, a21, a22, a23, a24, and a25 may adopt the values in Table 1 below.
  • a11, a12, a13, a14, a15, a21, a22, a23, a24, and a25 can also adopt the values in Table 2 below.
  • a11, a12, a13, a14, a15, a21, a22, a23, a24, and a25 may adopt the values in Table 3 below.
  • the aspheric lens 110 includes a main optical axis 501 and an aspheric lens surface.
  • the surface shape of the aspheric lens surface satisfies the following expression:
  • z is the axial distance of any point on the aspheric lens surface, that is, the distance between any point on the aspheric lens surface and the tangent plane 502 of the vertex of the aspheric lens surface (the distance along the main optical axis 501);
  • r is the radial distance of any point on the aspheric lens surface with respect to the main optical axis 501 (that is, the distance between any point on the aspheric lens surface and the main optical axis 501 in a direction perpendicular to the main optical axis 501);
  • c is the curvature of the aspheric lens surface, R is the curvature radius of the aspheric lens surface, k is the conic coefficient of the aspheric lens surface;
  • a1, a2, a3, a4 and a5 are the second-order aspheric coefficients and fourth-order aspheric coefficients of the aspheric lens surface, respectively Spherical coefficient, sixth-order asphe
  • the radius of curvature R of the aspheric lens surface refers to the radius of curvature of the apex of the aspheric lens surface.
  • the material of the lens 110 provided by the embodiment of the present disclosure can be selected according to actual application requirements.
  • the material of the lens 110 provided by the embodiment of the present disclosure may be optical plastic, optical glass or other suitable materials.
  • the radius of curvature of the first lens surface 111 (for example, the radius of curvature of the vertex of the first lens surface 111) is greater than the radius of curvature of the second lens surface 112 (for example, the radius of curvature of the second lens surface 112).
  • the radius of curvature of the vertex For example, the ratio of the radius of curvature of the first lens surface 111 to the radius of curvature of the second lens surface 112 is 4-6.
  • the radius of curvature of the first lens surface 111 may be between 70-100 mm.
  • any one of the following values can be selected as the radius of the first lens surface 111: 70.167 mm, 80.539 mm, 85.281 mm, 88.761 mm, 90.954 mm, 94.827 mm.
  • the radius of curvature of the second lens surface 112 may be between 10-30 mm.
  • any one of the following values can be selected as the radius of the second lens surface 112: 10.063 mm, 16.891 mm, 18.075 mm, 19.3984 mm, 20.532 mm, 25.113 mm, 29.084 mm.
  • the clear aperture (diameter) of the first lens surface 111 is slightly smaller than the clear aperture (diameter) of the second lens surface 112.
  • the clear aperture (diameter) of the first lens surface 111 may be between 10-25 mm.
  • any of the following values may be selected as the clear aperture of the first lens surface 111: 11.78 mm, 14.21 mm, 18.38 mm, 21.56 mm, 24.87 mm.
  • the clear aperture (diameter) of the second lens surface 112 may be between 10-25 mm.
  • any of the following values can be selected as the clear aperture of the second lens surface 112: 11.783 mm, 13.354 mm, 19.082 mm, 22.671 mm, 24.998 mm.
  • the absolute value of the thickness of the first lens surface 111 (that is, the distance between the first lens surface 111 and the microdisplay 140) is smaller (much smaller) than the thickness of the second lens surface 112 (that is, the first lens surface The absolute value of the distance between 111 and the second lens surface 112).
  • the ratio of the absolute value of the thickness of the second lens surface 112 to the absolute value of the thickness of the first lens surface 111 is between 30-40 (for example, 35-38).
  • the thickness of the first lens surface 111 is between -0.01 and -0.25 mm.
  • the thickness of the first lens surface 111 may be approximately -0.03 mm, -0.18 mm, -0.21 mm, or other suitable values.
  • the thickness of the second lens surface 112 (that is, the distance between the first lens surface 111 and the second lens surface 112) is between 2-5 mm (for example, 3 mm or 4 mm).
  • the optical path folding assembly 120 will be exemplified below. As shown in FIGS. 1 and 2, the optical path folding assembly 120 is configured to receive the light of the first image shaped (for example, enlarged) by the lens 110, and to fold the light from the lens 110 to the exit pupil 101 of the near-eye display device 100 The optical path can thereby reduce the volume of the near-eye display device 100, that is, make the near-eye display device 100 more compact.
  • the optical path folding assembly 120 includes a first transflective element 121 and a second transflective element 122 that are opposed to each other in a second direction D2 that crosses the first direction D1.
  • the first transflective element 121 and the second transflective element 122 are both partially transmissive and partially reflective elements.
  • the first transflective element 121 can simultaneously reflect and transmit light incident to the first transflective element 121, that is, the first transflective element 121 can reflect part of the light incident to the first transflective element 121, and at the same time, It is also possible to transmit part of the light incident to the first transflective element 121.
  • the reflectivity of the first transflective element 121 and the second transflective element 122 are both greater than or equal to 50%.
  • the light of the first image (that is, the light of the first image after the lens 110 has been shaped) may be sequentially reflected by the first transflective element 121 and by the second transflective element 122.
  • Reflected and transmitted by the first transflective element 121 that is, the light of the first image (that is, the light of the first image after the lens 110 is shaped) sequentially enters the first transflective element 121 and the second transflective element 122 and the first transflective element 121.
  • the transmission path of the light rays of the first image (the light rays of the first image shaped by the lens 110 and used for imaging) is described as follows. First, the light of the first image enters the first transflective element 121 and is reflected by the first transflective element 121; then, the light of the first image enters the second transflective element 122 and is reflected by the second transflective element 122. Reflection; Next, the light of the first image enters the first transflective element 121, and after passing through the first transflective element 121, it leaves the optical path folding assembly 120 and the near-eye display device 100.
  • One direction D1 is staggered with each other, but in practice, for the same light, the light incident to the second transflective element 122 and the light reflected by the second transflective element 122 coincide with each other in the first direction D1.
  • first transflective element 121 and the second transflective element 122 are both planar (planar or curved) transflective elements.
  • first transflective element 121 and the second transflective element 122 can form a hollow
  • the optical cavity can reduce the weight of the optical path folding assembly 120 and the near-eye display device 100, and improve the user experience.
  • the first transflective element 121 is a specular transflective element, and its working surface is flat.
  • the shape of the first transflective element 121 is a flat plate; in this case, the first transflective element 121
  • the radius of curvature of the transflective element 121 is infinite.
  • the angle between the specular reflection surface of the first transflective element 121 and the first direction D1 is equal to 45 degrees.
  • the first transflective element 121 can be made of related partially transmissive and partially reflective elements or materials made of lenses.
  • the first transflective element 121 may include a multilayer dielectric film.
  • the clear aperture (diameter) of the first transflective element 121 is between 25 mm and 35 mm, and the clear aperture of the first transflective element 121 is, for example, about 26.42 mm, 31.63 mm, or 34.18 mm.
  • the second transflective element 122 is a curved transflective element, so the second transflective element 122 can provide focal power and can be used to cooperate with the lens 110
  • the first image is reshaped, and therefore the combined structure of the lens 110 and the optical path folding assembly 120 can improve the reshaping ability and the reshaping effect of the first image.
  • the second transflective element 122 may be a spherical transflective element or an aspherical transflective element.
  • the curved surface of the second transflective element 122 toward the exit pupil 101 of the near-eye display device 100 is a concave curved surface.
  • the main optical axis of the second transflective element 122 is parallel to the second direction D2.
  • the first direction D1 is perpendicular to the second direction D2, that is, the main optical axis of the lens 110 and the main optical axis of the second transflective element 122 are perpendicular to each other.
  • the second transflective element 122 can be made of related partially transmissive and partially reflective elements or materials made of lenses.
  • the second transflective element 122 may include a multilayer dielectric film.
  • the absolute value of the radius of curvature of the second transflective element 122 is smaller than the radius of curvature of the first lens surface 111, and the absolute value of the radius of curvature of the second transflective element 122 is greater than that of the second lens surface 111.
  • the absolute value of the thickness of the second transflective element 122 is greater than the absolute value of the thickness of the first lens surface 111 and is greater than the absolute value of the thickness of the second lens surface 112.
  • the clear aperture of the second transflective element 122 is larger than the clear aperture of the first lens surface 111 and the second lens surface 112, and the clear aperture of the second transflective element 122 is smaller than the clear aperture of the first transflective element 121 Aperture.
  • the radius of curvature of the second transflective element 122 is between -45 mm and -35 mm.
  • the radius of curvature of the second transflective element 122 is approximately -43.162 mm, -40.828 mm, or -36.176 mm.
  • the thickness of the second transflective element 122 (that is, the distance between the second transflective element 122 and the first transflective element 121, or the main optical axis of the second transflective element 122 and the second transflective element 122 The distance between the intersection point and the main optical axis of the second transflective element 122 and the intersection point of the first transflective element 121) is between -15 mm and -5 mm.
  • the thickness of the second transflective element 122 is approximately -14.158 mm, -9.392 mm, -6.783 mm, or -5.012 mm.
  • the clear aperture (diameter) of the second transflective element 122 is between 25 mm and 30 mm.
  • the clear aperture of the second transflective element 122 is approximately 27.546 or 28.174.
  • the distance between the second lens surface 112 and the first transflective element 121 (the intersection of the main optical axis of the lens 110 and the second lens surface 112 and the intersection of the main optical axis of the lens 110 and the first transflective element 121 The distance between) is smaller than the distance between the second transflective element 122 and the first transflective element 121.
  • the distance between the second lens surface 112 and the first transflective element 121 is between 5 mm and 15 mm.
  • the distance between the second lens surface 112 and the first transflective element 121 is about 5.143 mm, 8.304 mm, 9.836 mm, or 13.153 mm.
  • the diameter of the exit pupil 101 of the near-eye display device 100 may be between 3 mm and 5 mm (for example, 4 mm).
  • the exit pupil position (or exit pupil distance) of the near-eye display device 100 may be located at 15 mm-30 mm (for example, 16.384 mm, 22.465 mm, or 28.021 mm). It should be noted that the exit pupil position of the near-eye display device 100 refers to the distance between the last optical surface of the near-eye display device 100 (that is, the first transflective element 121) and the exit pupil 101 of the near-eye display device 100 (for example, along The distance of the main optical axis of the second transflective element 122).
  • the combined structure of the lens 110 and the optical path folding assembly 120 may be called a reentrant optical system, which may be a coaxial reentrant optical system, that is, the main optical axis of the lens 110 and the second transflective element
  • the main optical axis of 122 intersects on the specular reflection surface of the first transflective element 121.
  • the coaxial reentrant optical system also has at least one of the advantages of lightness and thinness, large viewing angle, and low cost.
  • the specific structure and technical effects of the coaxial reentrant optical system can be referred to related technologies, and will not be repeated here.
  • intersection of the main optical axis of the lens 110 and the main optical axis of the second transflective element 122 may be recorded as the first intersection.
  • the main optical axis of the second transflective element 122 can be made to be at the second transflective element.
  • the length between the vertex of 122 and the first intersection is as small as possible, so that the size of the near-eye display device 100 is sufficiently small.
  • the length of the main optical axis of the second transflective element 122 between the apex of the second transflective element 122 and the first intersection is configured so that the light emitted by the most edge pixels of the microdisplay 140 can be incident on the first transflective element sequentially 121.
  • the second transflective element 122 and the first transflective element 121 then pass through the first transflective element 121 and enter the exit pupil 101 of the near-eye display system.
  • the first image displayed by the microdisplay 140 It can be completely imaged at the exit pupil 101, that is, the user can observe a complete first image at the exit pupil 101, thereby ensuring the user's experience.
  • the length of the main optical axis of the second transflective element 122 between the vertex of the second transflective element 122 and the first intersection is less than the length of the second lens surface 112 of the lens 110 in the second direction D2. length.
  • FIG. 4 shows the curvature of field and distortion of the near-eye display device 100 shown in FIGS. 1 and 2.
  • the field curvature of the near-eye display device 100 shown in Figures 1 and 2 is less than ⁇ 0.1 mm; when the field of view (half field of view) is less than At 15 degrees, the near-eye display device 100 shown in FIGS. 1 and 2 has pincushion distortion (correspondingly, the substrate takes a negative value), and the pincushion distortion rate is less than 5%.
  • FIG. 5 shows a modulation transfer function (MTF) curve of the near-eye display device 100 shown in FIGS. 1 and 2.
  • MTF modulation transfer function
  • the field of view (half field of view) when the field of view (half field of view) is 23 degrees, the user can distinguish information with high spatial frequency (for example, 62 line pairs/mm) in the image displayed by the near-eye display device 100 ( For example, detail information); in the case where the field of view (half field of view) is 25 degrees, although the user cannot well distinguish information with high spatial frequency (for example, detail information) in the image displayed by the near-eye display device 100 , But it is still possible to distinguish the information (for example, contour information) with medium and low spatial frequencies in the image displayed by the near-eye display device 100. Therefore, the field angle of the near-eye display device 100 shown in FIGS. 1 and 2 is greater than 50 degrees. For example, under the condition that the requirements for the volume of the near-eye display device 100 are appropriately relaxed, the field of view of the near-eye display device 100 may be between 50 degrees and 90 degrees, thereby improving the user experience.
  • high spatial frequency for example, 62 line pairs/mm
  • the image displayed by the near-eye display device 100 provided by the embodiment of the present disclosure meets the user's demand for picture quality.
  • the main optical axis of the second transflective element can be set between the vertex of the second transflective element and the first image.
  • the length between one intersection is as small as possible, so that the size of the near-eye display device is sufficiently small.
  • double aspherical lenses to improve the picture quality of the near-eye display device, it is possible to make the picture displayed by the near-eye display device meet the needs of users when the size of the near-eye display device is small enough, thereby improving the user's comprehensive experience .
  • FIG. 6 is a schematic structural diagram of another near-eye display device 200 provided by at least one embodiment of the present disclosure.
  • the near-eye display device 200 shown in FIG. 6 can be implemented as monocular virtual reality glasses or binocular virtual reality glasses.
  • the near-eye display device 200 shown in 6 may also be implemented as a virtual reality helmet or other applicable virtual reality display device.
  • the near-eye display device 200 includes a lens 210 and an optical path folding assembly 220.
  • the near-eye display device 200 further includes a microdisplay 240, a polarizer 232 and a quarter wave plate 231.
  • the combined structure of the lens 210 and the optical path folding component 220 may be referred to as a reentrant optical system.
  • the lens 210 is configured to receive the projection light of the first image projected by the microdisplay 240, and to shape the first image (for example, enlarge the first image).
  • the lens 210 is configured to magnify the first image to an image suitable for human eyes; in other examples, the lens 210 and the optical path folding component 220 cooperate with each other to magnify the first image to be suitable for human eyes. Image; In still other examples, the lens 210 is also configured to adjust the shape of the first image to an image suitable for human eyes to observe, reducing image distortion.
  • the lens 210 includes a main optical axis (not shown in the figure), and a first lens surface 211 and a second lens surface 212 opposed to each other in a first direction D1 where the main optical axis of the lens 210 is located.
  • the first lens surface 211 is closer to the micro display 240 than the second lens surface 212.
  • the first lens surface 211 and the second lens surface 212 are both aspherical surfaces (for example, even-order aspherical surfaces), that is, the lens 210 provided by at least one embodiment of the present disclosure is a double aspherical lens 210.
  • the surface shape of the first lens surface 211 and the surface shape of the second lens surface 212 of the lens 210, the specific arrangement method and the technical effect can be referred to the near-eye display device 200 shown in FIGS. 1 and 2, which will not be repeated here.
  • the volume of the near-eye display device 200 can be reduced as much as possible by optimizing the optical path folding assembly 220, thereby improving the user experience.
  • the polarizer 232 is located on the light incident side of the lens 210 in the first direction D1 (that is, between the lens 210 and the microdisplay 240 in the first direction D1), and is configured such that the polarizer
  • the polarized light emitted by 232 is s-polarized light (sL).
  • the polarizer 232 provided by at least one embodiment of the present disclosure may also be located on the light exit side of the lens 210 in the first direction D1 (that is, located on the side of the lens 210 away from the microdisplay 240 in the first direction D1). One side).
  • the optical path folding assembly 220 is configured to receive the light rays of the first image shaped by the lens 210 and to fold the optical path from the lens 210 to the exit pupil 201 of the near-eye display device 200.
  • the optical path folding assembly 220 includes a first transflective element 221 and a second transflective element 222 facing each other in a second direction D2 crossing the first direction D1.
  • the first transflective element 221 is a polarization splitting element, and the polarization splitting element has high reflectivity for s-polarized light (for example, the reflectance is greater than 90%, for example, 100%), and high transmittance for p-polarized light. (For example, the transmittance is greater than 90%, for example, 100%).
  • the shape of the polarization beam splitting element is flat, so that the first transflective element 221 and the second transflective element 222 can form a hollow optical cavity, thereby reducing the weight of the optical path folding assembly 220 and the near-eye display device 200 , To improve the user experience.
  • the second transflective element 222 is a curved transflective element (for example, a spherical transflective element or a non-curved transflective element), and thus, the second transflective element 222 can also provide light.
  • the focal power can also be used to cooperate with the lens 210 to shape the first image, and therefore, the combined structure of the lens 210 and the optical path folding assembly 220 can improve the shaping and shaping effect of the first image.
  • the curved surface of the second transflective element 222 toward the exit pupil 201 of the near-eye display device 200 is a concave curved surface.
  • the main optical axis of the second transflective element 222 is parallel to the second direction D2.
  • the first direction D1 is perpendicular to the second direction D2, that is, the main optical axis of the lens 210 and the main optical axis of the second transflective element 222 are perpendicular to each other.
  • the second transflective element 222 can be made of related partially transmissive and partially reflective elements or materials made of lenses.
  • the second transflective element 222 may include a multilayer dielectric film.
  • the quarter-wave plate 231 is disposed between the first transflective element 221 and the second transflective element 222 in the second direction D2, and the light of the first image is sequentially transferred by the first transflective element 221 is reflected, transmitted by the quarter-wave plate 231, reflected by the second transflective element 222, transmitted by the quarter-wave plate 231, and transmitted by the first transflective element 221.
  • the transmission path of the light of the first image (the light of the first image used for imaging) is described as follows. First, the light of the first image (s-polarized light sL) enters the first transflective element 221 and is reflected by the first transflective element 221; then, the light of the first image enters the quarter wave plate 231, and Pass through the quarter wave plate 231, and the quarter wave plate 231 converts the light of the first image from s-polarized light sL to circularly polarized light cL; then, the light of the first image (circularly polarized light cL) enters To the second transflective element 222 and reflected by the second transflective element 222; fourth, the light of the first image (circularly polarized light cL) enters the quarter wave plate 231 and passes through the quarter wave plate 231 And, the quarter-wave plate 231 converts the light of the first image from circularly polarized light cL to p-polarized light pL; fifth
  • ⁇ 1 is the transmittance of the polarizer 232 to the light incident on the polarizer 232
  • ⁇ 11 is the reflectance of the first transflective element 221 to the light of the first image incident on the first transflective element 221
  • ⁇ 12 Is the reflectivity of the second transflective element 222 to the light of the first image incident on the second transflective element 222
  • ⁇ 13 is the reflectivity of the first transflective element 221 to the first image incident on the first transflective element 221
  • the transmittance of light is the transmittance of light.
  • the light utilization efficiency ⁇ 1 of the near-eye display device 200 can be increased to 30%.
  • ⁇ 21 is the reflectivity of the first transflective element 221 to the light of the first image incident on the first transflective element 221
  • ⁇ 22 is the reflectivity of the second transflective element 222 to the light incident on the second transflective element 222
  • ⁇ 23 is the transmittance of the first transflective element 221 to the light of the first image incident on the first transflective element 221.
  • the light utilization efficiency ⁇ 2 of the near-eye display device 200 may not exceed 20%.
  • the light utilization efficiency of the near-eye display device 200 shown in FIG. 6 has been improved, so the power consumption and battery life of the near-eye display device 200 can be reduced. Time, which can improve the user experience.
  • FIG. 7 is another schematic diagram of another structure of another near-eye display device provided by at least one embodiment of the present disclosure. As shown in FIG. 7, the intersection of the extension line of the first transflective element 221 and the extension line of the second transflective element 222 is located on the plane where the quarter wave plate 231 is located, thereby making it possible to make the quarter wave plate 231
  • the clear aperture is as large as possible, so the light utilization efficiency of the near-eye display device 200 shown in FIGS. 6 and 7 can be further improved.
  • the combined structure of the lens 210 and the optical path folding assembly 220 may be called a reentrant optical system or a coaxial reentrant optical system, that is, the main optical axis of the lens 210 and the main optical axis of the second transflective element 222
  • the specular reflection surfaces of the first transflective element 221 intersect.
  • the intersection of the main optical axis of the lens 210 and the main optical axis of the second transflective element 222 may be recorded as the first intersection.
  • the main optical axis of the second transflective element 222 can be made to be at the second transflective element.
  • the length between the vertex of 222 and the first intersection point is as small as possible, so that the size of the near-eye display device 200 is sufficiently small.
  • the length of the main optical axis of the second transflective element 222 between the vertex of the second transflective element 222 and the first intersection is less than the length of the second lens surface 212 of the lens 210 in the second direction D2. length.
  • the light utilization efficiency of the near-eye display device refers to the light intensity of the light leaving the optical path folding assembly and the near-eye display device via the first transflective element and the light intensity of the light emitted by the microdisplay Ratio.
  • intersection of the extension line of the first transflective element and the extension line of the second transflective element can also be the plane where the quarter wave plate is located.
  • Interval settings (interval settings in the second direction D2).
  • the near-eye display device may not be provided with a polarizer.
  • the volume and appearance shape of the near-eye display device shown in FIG. 6 may be the same as and similar to those of the near-eye display device shown in FIG. 1 and FIG. 2.
  • the main optical axis of the second transflective element can be set between the vertex of the second transflective element and the first image.
  • the length between one intersection is as small as possible, so that the size of the near-eye display device is sufficiently small.
  • double aspherical lenses to improve the picture quality of the near-eye display device, it is possible to make the picture displayed by the near-eye display device meet the needs of users when the size of the near-eye display device is small enough, thereby improving the user's comprehensive experience .
  • the light utilization efficiency of the near-eye display device can be improved, thereby reducing the power consumption and battery life of the near-eye display device, and further improving the user experience.
  • Fig. 8 shows a binocular virtual reality glasses provided by at least one embodiment of the present disclosure.
  • the near-eye display device provided by the embodiment of the present disclosure may be implemented as the binocular virtual reality glasses shown in FIG. 8.
  • the lens and the micro display can be arranged in the upper area of the virtual reality glasses, and the first transflective element is closer to the user's eyes than the second transflective element.
  • the near-eye display device provided by at least one embodiment of the present disclosure reduces at least one of the volume, weight, and power consumption of the near-eye display device, and can improve the light utilization rate of the near-eye display device, thereby making at least one of the
  • the near-eye display device and binocular virtual reality glasses provided by the embodiments are suitable for wearing in daily life.

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Abstract

一种近眼显示装置（100，200），包括透镜（110，210）和光路折叠组件（120，220）。透镜（110，210）被配置为接收微显示器（140，240）投射的第一图像的投射光，且对第一图像进行整形；透镜（110，210）包括主光轴以及在透镜（110，210）的主光轴所在的第一方向（D1）上对置的第一透镜面（111，211）和第二透镜面（112，212），第一透镜面（111，211）和第二透镜面（112，212）均为非球面；光路折叠组件（120，220）被配置为接收由透镜（110，210）整形后的第一图像的光线，以及折叠从透镜（110，210）至近眼显示装置（100，200）的出瞳（101，201）的光路。通过采用双非球面透镜（110，210），可以提升近眼显示装置（100，200）的成像质量，并降低近眼显示装置（100，200）的厚度。

Description

近眼显示装置
对相关申请的交叉参考
本申请要求于2019年2月28日递交的中国专利申请第201910152310.8号的优先权，在此全文引用上述中国专利申请公开的内容以作为本申请的一部分。
技术领域
本公开的实施例涉及一种近眼显示装置。
背景技术
增强现实(Augmented Reality，AR)显示装置通过将AR显示装置显示的虚拟场景图像叠加在外界真实场景中，可以实现外界真实场景与虚拟场景的融合。因此，增强现实显示装置可以提升用户对现实世界的认知能力，由此可以提升用户的使用体验。
发明内容
本公开的至少一个实施例提供了一种近眼显示装置，该近眼显示装置包括透镜和光路折叠组件。所述透镜被配置为接收微显示器投射的第一图像的投射光，且对所述第一图像进行整形；所述透镜包括主光轴以及在所述透镜的主光轴所在的第一方向上对置的第一透镜面和第二透镜面，所述第一透镜面和所述第二透镜面均为非球面；所述光路折叠组件被配置为接收由所述透镜整形后的所述第一图像的光线，以及折叠从所述透镜至所述近眼显示装置的出瞳的光路。
例如，在所示近眼显示装置的至少一个示例中，所述光路折叠组件包括在与所述第一方向交叉的第二方向上对置的第一透射反射元件和第二透射反射元件，且所述第一图像的光线顺次由所述第一透射反射元件反射、由所述第二透射反射元件反射以及由所述第一透射反射元件透射。
例如，在所示近眼显示装置的至少一个示例中，所述第一透射反射元件为镜面透射反射元件。
例如，在所示近眼显示装置的至少一个示例中，所述第二透射反射元件为曲面透射反射元件，且所述第二透射反射元件朝向所述近眼显示装置的出瞳的曲面为凹曲面。
例如，在所示近眼显示装置的至少一个示例中，所述第二透射反射元件的主光轴与所述第二方向平行；所述透镜的主光轴和所述第二透射反射元件的主光轴在所述第一透射反射元件的镜面反射面上相交；所述第一透射反射元件的镜面反射面与所述第一方向的夹角等于45度。
例如，在所示近眼显示装置的至少一个示例中，述第一透射反射元件为偏振分光元件。
例如，在所示近眼显示装置的至少一个示例中，近眼显示装置还包括1/4波片，所述1/4波片在所述第二方向上设置在所述第一透射反射元件和所述第二透射反射元件之间，且所述第一图像的光线顺次由所述第一透射反射元件反射、由所述1/4波片透射、由所述第二透射反射元件反射、由所述1/4波片透射以及由所述第一透射反射元件透射。
例如，在所示近眼显示装置的至少一个示例中，所述第一方向与所述第二方向垂直，所述第二方向垂直于所述1/4波片。
例如，在所示近眼显示装置的至少一个示例中，所述第一透射反射元件的延长线和所述第二透射反射元件的延长线的交点位于所述1/4波片所在的平面。
例如，在所示近眼显示装置的至少一个示例中，近眼显示装置还包括偏光片，在所述第一方向上位于所述透镜的入光侧或出光侧。所述偏光片配置为使得从所述偏光片出射的偏振光为s-偏振光；以及所述偏振分光元件配置为反射所述s-偏振光。
例如，在所示近眼显示装置的至少一个示例中，所述第一透射反射元件和所述第二透射反射元件的反射率均大于等于50％。
例如，在所示近眼显示装置的至少一个示例中，相比于所述第二透镜面，所述第一透镜面更靠近所述微显示器；以及所述第一透镜面的曲率半径大于所述第二透镜面的曲率半径。
例如，在所示近眼显示装置的至少一个示例中，所述第一透镜面和所述第二透镜面均为偶次非球面；所述透镜的第一透镜面的表面形状z满足以下的表达式(1)，所述透镜的第二透镜面的表面形状z满足以下的表达式(2)：
Figure PCTCN2019125187-appb-000001
Figure PCTCN2019125187-appb-000002
z1为所述第一透镜面上任一点的相对于所述第一透镜面的顶点的切面的轴向间距；r1为所述第一透镜面上任一点相对于所述透镜的主光轴的径向距离；c1是所述第一透镜面的曲率，k1是所述第一透镜面的圆锥系数；a11、a12、a13、a14和a15分别是所述第一透镜面的二阶非球面系数、四阶非球面系数、六阶非球面系数、八阶非球面系数和十阶非球面系数；z2为所述第二透镜面上任一点的相对于所述第二透镜面的顶点的切面的轴向间距；r2为所述第二透镜面上任一点相对于所述透镜的主光轴的径向距离；c2是所述第二透镜面的曲率，k2是所述第二透镜面的圆锥系数；a21、a22、a23、a24和a25分别是所述第二透镜面的二阶非球面系数、四阶非球面系数、六阶非球面系数、八阶非球面系数和十阶非球面系数。
例如，在所示近眼显示装置的至少一个示例中，a11、a12、a13、a14和a15分别满足以下范围：
-0.9×10 -4＜a11＜1×10 -4
-10×10 -3＜a12＜-1×10 -3
1×10 -5＜a13＜10×10 -5
-10×10 -9＜a14＜-1×10 -9
-10×10 -10＜a15＜-1×10 -10
a21、a22、a23、a24和a25分别满足以下范围：
-0.9×10 -4＜a21＜1×10 -4
1×10 -4＜a22＜10×10 -4
-10×10 -6＜a23＜-1×10 -6。
-10×10 -7＜a24＜-1×10 -7
1×10 -10＜a25＜10×10 -10
例如，在所示近眼显示装置的至少一个示例中，近眼显示装置还包括微显示器，所述微显示器配置为朝向所述透镜投射所述第一图像的投射光。
附图说明
为了更清楚地说明本公开实施例的技术方案，下面将对实施例的附图作简单地介绍，显而易见地，下面描述中的附图仅仅涉及本公开的一些实施例，而非对本公开的限制。
图1是本公开的至少一个实施例提供的一种近眼显示装置的结构示意图；
图2是图1示出的近眼显示装置的光路的示意图；
图3是一种非球面透镜；
图4是图1和图2所示的近眼显示装置的场曲和畸变的示意图；
图5是图1和图2所示的近眼显示装置的调制传递函数曲线的示意图；
图6是本公开的至少一个实施例提供的另一种近眼显示装置的一种结构示意图；
图7是本公开的至少一个实施例提供的另一种近眼显示装置的另一种结构示意图；以及
图8是本公开的至少一个实施例提供的一种双目式虚拟现实眼镜。
具体实施方式
为使本公开实施例的目的、技术方案和优点更加清楚，下面将结合本公开实施例的附图，对本公开实施例的技术方案进行清楚、完整地描述。显然，所描述的实施例是本公开的一部分实施例，而不是全部的实施例。基于所描述的本公开的实施例，本领域普通技术人员在无需创造性劳动的前提下所获得的所有其他实施例，都属于本公开保护的范围。
除非另作定义，此处使用的技术术语或者科学术语应当为本公开所属领域内具有一般技能的人士所理解的通常意义。本公开中使用的“第一”、“第二”以及类似的词语并不表示任何顺序、数量或者重要性，而只是用来区分不同的组成部分。同样，“包括”或者“包含”等类似的词语意指出现该词前面的元件或者物件涵盖出现在该词后面列举的元件或者物件及其等同，而不排除其他元件或者物件。“连接”或者“相连”等类似的词语并非限定于物理的或者机械的连接，而是可以包括电性的连接，不管是直接的还是间接的。“上”、“下”、“左”、“右”等仅用于表示相对位置关系，当被描述对象的绝对位置改变后，则该相对位置关系也可能相应地改变。
本公开的发明人注意到，当前的增强现实型近眼显示装置的尺寸和重量较大，光利用效率较低(也即，功耗较大)，视场角(FOV，field of view)较小，这与消费者对近眼显示装置的要求和期待相违背，并使得消费者难以在日常生活中佩戴近眼显示装置。
本公开的至少一个实施例提供了一种近眼显示装置，该近眼显示装置包 括透镜和光路折叠组件。透镜被配置为接收微显示器投射的第一图像的投射光，且对第一图像进行整形；透镜包括主光轴以及在透镜的主光轴所在的第一方向上对置的第一透镜面和第二透镜面，第一透镜面和第二透镜面均为非球面；光路折叠组件被配置为接收由透镜整形后的第一图像的光线，以及折叠从透镜至近眼显示装置的出瞳的光路。
需要说明的是，在本公开的至少一个实施例中，近眼显示装置的出瞳是近眼显示装置的孔径光阑在近眼显示装置的像空间所成的像。例如，近眼显示装置的孔径光阑是指近眼显示装置中限制出射光束的有效孔径。出瞳的位置(由出瞳距离表示)和直径(由出瞳直径表示)代表了出射光束的位置和口径。例如，使用近眼显示装置时，可以使得用户的瞳孔位于近眼显示装置的出瞳，以使得用户能够观察到近眼显示装置的整个视场。例如，在本公开的至少一个实施例中，近眼显示装置的出瞳和近眼显示装置的孔径光阑彼此重合。
需要说明的是，在本公开的至少一个实施例中，第一透镜面的中心的曲率半径到第一透镜面的边缘的曲率半径为非恒定值(例如，连续变化)。例如，第一透镜面的中心的曲率半径小于第一透镜面的边缘的曲率半径；第二透镜面的中心的曲率半径到第二透镜面的边缘的曲率半径为非恒定值(例如，连续变化)。例如，第二透镜面的中心的曲率半径小于第二透镜面的边缘的曲率半径。
在一些示例中，通过采用双非球面透镜，相比与采用球面透镜以同样实现对于第一图像进行整形而言，可以降低近眼显示装置的成像质量，降低近眼显示装置的厚度。
在一些示例中，通过采用双非球面透镜提升近眼显示装置的画面质量，可以尽可能的降低近眼显示装置的体积，由此可以提升用户的使用体验。
下面通过几个实施例或示例对根据本公开实施例提供的近眼显示装置进行非限制性的说明，如下面所描述的，在不相互抵触的情况下这些具体的实施例或示例中不同特征可以相互组合，从而得到新的实施例或示例，这些新的实施例或示例也都属于本公开保护的范围。
图1是本公开的至少一个实施例提供的一种近眼显示装置100的结构示意图，图2是图1示出的近眼显示装置100的光路的示意图。需要说明的是，图2示出了近眼显示装置100为基于图2下方的比例尺等比例绘制的图形； 为描述方便，图2还示出了微显示器140。
图1和图2示出的近眼显示装置100可以实现为单目式虚拟现实眼镜或双目式虚拟现实眼镜，图1和图2示出的近眼显示装置100还可以实现为虚拟现实头盔或其它适用的虚拟现实显示装置。
如图1所示，该近眼显示装置100包括透镜110和光路折叠组件120。根据实际应用需求，如图2所示，该近眼显示装置100还包括微显示器140。例如，透镜110和光路折叠组件120的组合结构可被称为折返式光学系统。
这里，微显示器是指对角线长度小于2英寸(约5厘米)的显示器。例如，本公开的至少一个实施例提供的微显示器140的尺寸位于0.5英寸-1英寸之间，微显示器140的尺寸例如为0.7英寸或0.8英寸。例如，微显示器140可以基于微型OLED(微型有机发光二级管)技术、MicroLED(微型发光二极管)技术、全息显示技术、硅基液晶(LCoS)技术、数字光处理(DLP)技术或者其它适用的微型显示器件技术实现。
如图2所示，微显示器140配置为朝向透镜110投射第一图像的投射光。例如，微显示器140显示的图像作为近眼显示装置100的“物”，并且，微显示器140显示的图像位于同一平面内，也即，近眼显示装置100的“物”的曲率半径为无穷大。例如，在一个示范性示例中，微显示器140显示的图像的尺寸(微显示器140显示的图像的对角线长度)为17.682毫米。
如图2所示，透镜110被配置为接收微显示器140投射的第一图像的投射光，且对第一图像进行整形(例如，放大第一图像)，从而得到适于通过后续的光路折叠组件120呈现给用户的显示图像。在一些示例中，透镜110被配置为将第一图像放大至适合人眼观察的图像；在另一些示例中，透镜110与光路折叠组件120彼此配合以将第一图像放大至适合人眼观察的图像(或者，用于显示的图像)；在再一些示例中，透镜110还被配置为将第一图像的形状调整至适合人眼观察的图像，减小图像的畸变。例如，上述适合人眼观察的图像(或者，用于显示的图像)的畸变较小(例如，无畸变)。
如图1和图2所示，透镜110包括主光轴(图中未示出)以及在透镜110的主光轴所在的第一方向D1上对置的第一透镜面111和第二透镜面112，相比于第二透镜面112，第一透镜面111更靠近微显示器140。需要说明的是，透镜110的主光轴是指穿过第一透镜面111的中心(球心)和第二透镜面112的中心(球心)的直线(虚拟的直线)。
如图1和图2所示，第一透镜面111和第二透镜面112均为非球面，也即，本公开的至少一个实施例提供的透镜110为双非球面透镜。例如，第一透镜面111和第二透镜面112的非球面选择来使得对第一图像进行整形(例如，放大)，得到适于通过后续的光路折叠组件120呈现给用户的显示图像，而且相比与采用球面透镜以同样实现对于第一图像进行整形而言，可以降低近眼显示装置的成像质量，降低近眼显示装置的厚度。例如，通过使得透镜110为双非球面透镜，可以在无需采用自由曲面透镜(或其它采用了高级曲面的透镜)的情况下，提升近眼显示装置100的成像质量，由此可以降低透镜110的制造难度和制造成本。
如图1和图2所示，第一透镜面111和第二透镜面112为朝向相反方向凸出的凸曲面，因此透镜110为凸透镜(例如，双凸透镜)。例如，第一透镜面111为朝向微显示器140凸出的凸曲面，第二透镜面112为背离微显示器140凸出的凸曲面。
例如，通过采用双非球面透镜提升近眼显示装置100的画面质量，可以通过优化光路折叠组件120，降低近眼显示装置100的体积，由此可以提升用户的使用体验。
下面对透镜110的具体结构和参数做示例性说明。
例如，第一透镜面111为偶次非球面。例如，透镜110的第一透镜面111的表面形状满足以下的表达式：
Figure PCTCN2019125187-appb-000003
此处，z1为第一透镜面111上任一点的相对于第一透镜面111的顶点的切面的轴向间距；r1为上述第一透镜面111上任一点相对于透镜110的主光轴的径向距离；c1是第一透镜面111的曲率，k1是第一透镜面111的圆锥系数；a11、a12、a13、a14和a15分别是第一透镜面111的二阶非球面系数、四阶非球面系数、六阶非球面系数、八阶非球面系数和十阶非球面系数。
例如，第二透镜面112为偶次非球面。例如，透镜110的第二透镜面112的表面形状z2满足以下的表达式：
Figure PCTCN2019125187-appb-000004
此处，z2为第二透镜面112上任一点相对于第二透镜面112的顶点的切面的轴向间距；r2为第二透镜面112上的任一点相对于透镜110的主光轴的 径向距离；c2是第二透镜面112的曲率，k2是第二透镜面112的圆锥系数；a21、a22、a23、a24和a25分别是第二透镜面112的二阶非球面系数、四阶非球面系数、六阶非球面系数、八阶非球面系数和十阶非球面系数。
例如，a11、a12、a13、a14和a15分别满足以下范围：
-0.9×10 -4＜a11＜1×10 -4
-10×10 -3＜a12＜-1×10 -3
1×10 -5＜a13＜10×10 -5。
-10×10 -9＜a14＜-1×10 -9
-10×10 -10＜a15＜-1×10 -10
例如，a21、a22、a23、a24和a25分别满足以下范围：
-0.9×10 -4＜a21＜1×10 -4
1×10 -4＜a22＜10×10 -4
-10×10 -6＜a23＜-1×10 -6。
-10×10 -7＜a24＜-1×10 -7
1×10 -10＜a25＜10×10 -10
在一个示例中，a11、a12、a13、a14、a15、a21、a22、a23、a24和a25可以采用以下表1中的数值。
表1
a11 a12 a13 a14 a15
0 -1.014×10 -3 1.384×10 -5 -4.658×10 -9 -4.363×10 -10
a21 a22 a23 a24 a25
0 5.456×10 -4 -3.086×10 -6 -1.498×10 -7 9.868×10 -10
在另一个示例中，a11、a12、a13、a14、a15、a21、a22、a23、a24和a25还可以采用以下表2中的数值。
表2
a11 a12 a13 a14 a15
0 -5.014×10 -3 1.784×10 -5 -4.656×10 -9 -1.363×10 -10
a21 a22 a23 a24 a25
0 3.456×10 -4 -1.086×10 -6 -5.498×10 -7 7.868×10 -10
在再一个示例中，a11、a12、a13、a14、a15、a21、a22、a23、a24和a25可以采用以下表3中的数值。
表3
a11 a12 a13 a14 a15
0.001 -4.014×10 -3 2.384×10 -5 -4.668×10 -9 -4.363×10 -10
a21 a22 a23 a24 a25
0.001 3.456×10 -4 -1.086×10 -6 -1.468×10 -7 9.868×10 -10
为了更为清楚的理解透镜110的第一透镜面111和第二透镜面112的各个参数，下面结合图3示出的非球面透镜对非球面透镜110及相关参数做示例性说明。如图3所示，该非球面透镜110包括主光轴501和非球透镜面。非球透镜面的表面形状满足以下的表达式：
Figure PCTCN2019125187-appb-000005
此处，z为非球透镜面上任一点的轴向间距，也即，非球透镜面上任一点与非球透镜面的顶点的切面502之间的间距(沿主光轴501方向的间距)；r为上述非球透镜面上任一点相对于主光轴501的径向距离(也即，上述非球透镜面上任一点与主光轴501之间的沿垂直于主光轴501方向的间距)；c是非球透镜面的曲率，R是非球透镜面的曲率半径，k是非球透镜面的圆锥系数；a1、a2、a3、a4和a5分别是非球透镜面的二阶非球面系数、四阶非球面系数、六阶非球面系数、八阶非球面系数和十阶非球面系数。非球透镜面上的各个点的轴向间距和径向距离的组合可用于示出非球透镜面的表面形状。
需要说明的是，在本公开的至少一个示例中，非球透镜面的曲率半径R是指非球透镜面的顶点的曲率半径。
例如，本公开的实施例提供的透镜110的材料可以根据实际应用需求进行选择。例如，本公开的实施例提供的透镜110的材料可以为光学塑料、光学玻璃或者其它适用的材料。
例如，如图1和图2所示，第一透镜面111的曲率半径(例如，第一透镜面111的顶点曲率半径)大于第二透镜面112的曲率半径(例如，第二透镜面112的顶点曲率半径)。例如，第一透镜面111的曲率半径与第二透镜面 112的曲率半径的比值位于4-6。例如，第一透镜面111的曲率半径可以位于70-100毫米之间。例如，可以选用以下任一个数值的作为第一透镜面111的半径：70.167毫米、80.539毫米、85.281毫米、88.761毫米、90.954毫米、94.827毫米。例如，第二透镜面112的曲率半径可以位于10-30毫米之间。例如，可以选用以下任一个数值作为第二透镜面112的半径：10.063毫米、16.891毫米、18.075毫米、19.3984毫米、20.532毫米、25.113毫米、29.084毫米。
例如，第一透镜面111的通光孔径(直径)略小于第二透镜面112的通光孔径(直径)。例如，第一透镜面111的通光孔径(直径)可以位于10-25毫米之间。例如，可以选用以下任一个数值的作为第一透镜面111的通光孔径：11.78毫米、14.21毫米、18.38毫米、21.56毫米、24.87毫米。例如，第二透镜面112的通光孔径(直径)可以位于10-25毫米之间。例如，可以选用以下任一个数值的作为第二透镜面112的通光孔径：11.783毫米、13.354毫米、19.082毫米、22.671毫米、24.998毫米。
例如，第一透镜面111的厚度(也即，第一透镜面111与微显示器140之间的间距)的绝对值小于(远小于)第二透镜面112的厚度(也即，第一透镜面111与第二透镜面112之间的间距)的绝对值。例如，第二透镜面112的厚度的绝对值与第一透镜面111的厚度的绝对值的比值位于30-40(例如，35-38)之间。
例如，第一透镜面111的厚度位于-0.01至-0.25毫米之间。例如，第一透镜面111的厚度可以约为-0.03毫米、-0.108毫米、-0.21毫米或其它适用数值。例如，第二透镜面112的厚度(也即，第一透镜面111与第二透镜面112之间的间距)位于2-5毫米(例如，3毫米或4毫米)之间。
下面对光路折叠组件120进行示例性说明。如图1和图2所示，光路折叠组件120被配置为接收由透镜110整形后(例如，放大后)的第一图像的光线，以及折叠从透镜110至近眼显示装置100的出瞳101的光路，由此可以减小近眼显示装置100的体积，也即，使得近眼显示装置100更为紧凑。
例如，如图1和图2所示，光路折叠组件120包括在与第一方向D1交叉的第二方向D2上对置的第一透射反射元件121和第二透射反射元件122。例如，第一透射反射元件121和第二透射反射元件122均为部分透射部分反射元件。例如，第一透射反射元件121可以同时反射和透射入射到第一透射反射元件121光线，也即，第一透射反射元件121可以反射部分入射到第一透 射反射元件121的光线，与此同时，还可以透射部分入射到第一透射反射元件121的光线。例如，第一透射反射元件121和第二透射反射元件122的反射率均大于等于50％。
例如，如图1和图2所示，第一图像的光线(也即，透镜110整形后的第一图像的光线)可以顺次由第一透射反射元件121反射、由第二透射反射元件122反射以及由第一透射反射元件121透射，也即，第一图像的光线(也即，透镜110整形后的第一图像的光线)顺次入射至第一透射反射元件121、第二透射反射元件122和第一透射反射元件121。
如图1和图2所示，第一图像的光线(透镜110整形后的且用于成像的第一图像的光线)的传输路径描述如下。首先，第一图像的光线入射至第一透射反射元件121，并被第一透射反射元件121反射；然后，第一图像的光线入射至第二透射反射元件122，并被第二透射反射元件122反射；接着，第一图像的光线入射至第一透射反射元件121，并在穿过第一透射反射元件121后离开光路折叠组件120和近眼显示装置100。
需要说明的是，为方便描述，在图1所示的示例中以及本公开实施例的其它示例中，入射至第二透射反射元件122的光线以及被第二透射反射元件122反射的光线在第一方向D1上彼此错开，但在实践中，对于同一根光线，入射至第二透射反射元件122的光线以及被第二透射反射元件122反射的光线在第一方向D1上彼此重合。
例如，第一透射反射元件121和第二透射反射元件122均为面状(平面或曲面)透射反射元件，此种情况下，第一透射反射元件121和第二透射反射元件122可以形成一个中空的光学腔，由此可以减小光路折叠组件120和近眼显示装置100的重量，提高用户的使用体验。
例如，如图1和图2所示，第一透射反射元件121为镜面透射反射元件，其工作表面为平面，例如，第一透射反射元件121的形状为平板状；此种情况下，第一透射反射元件121的曲率半径为无穷大。例如，第一透射反射元件121的镜面反射面与第一方向D1的夹角等于45度。例如，可选用相关的部分透射部分反射元件或镜片的制作材料制作第一透射反射元件121。例如，第一透射反射元件121可以包括多层介质薄膜。例如，第一透射反射元件121的通光孔径(直径)位于25毫米-35毫米，第一透射反射元件121的通光孔径例如约为26.42毫米、31.63毫米或34.18毫米。
例如，如图1和图2所示，第二透射反射元件122为曲面透射反射元件，由此，第二透射反射元件122可以提供光焦度(focal power)，并可以用于与透镜110协作对第一图像进行整形，并因此可以提升透镜110和光路折叠组件120的组合结构对第一图像的整形能力和整形效果。例如，第二透射反射元件122可以为球面透射反射元件或非球面透射反射元件。
例如，如图1和图2所示，第二透射反射元件122朝向近眼显示装置100的出瞳101的曲面为凹曲面。例如，第二透射反射元件122的主光轴与第二方向D2平行。例如，第一方向D1与第二方向D2垂直，也即，透镜110的主光轴与第二透射反射元件122的主光轴彼此垂直。例如，可选用相关的部分透射部分反射元件或镜片的制作材料制作第二透射反射元件122。例如，第二透射反射元件122可以包括多层介质薄膜。
例如，如图1和图2所示，第二透射反射元件122的曲率半径的绝对值小于第一透镜面111的曲率半径，并且，第二透射反射元件122的曲率半径的绝对值大于第二透镜面112的曲率半径。例如，第二透射反射元件122的厚度的绝对值大于第一透镜面111的厚度的绝对值以及大于第二透镜面112的厚度的绝对值。例如，第二透射反射元件122的通光孔径大于第一透镜面111和第二透镜面112的通光孔径，且第二透射反射元件122的通光孔径小于第一透射反射元件121的通光孔径。
例如，第二透射反射元件122的曲率半径位于-45毫米至-35毫米之间。例如，第二透射反射元件122的曲率半径约为-43.162毫米、-40.828毫米或-36.176毫米。例如，第二透射反射元件122的厚度(也即，第二透射反射元件122与第一透射反射元件121之间的距离，或者第二透射反射元件122的主光轴与第二透射反射元件122的交点与第二透射反射元件122的主光轴与第一透射反射元件121的交点之间的间距)位于-15毫米至-5毫米之间。例如，第二透射反射元件122的厚度约为-14.158毫米、-9.392毫米、-6.783毫米或-5.012毫米。例如，第二透射反射元件122的通光孔径(直径)位于25毫米-30毫米之间。例如，第二透射反射元件122的通光孔径约为27.546或28.174。
例如，第二透镜面112的与第一透射反射元件121之间的间距(透镜110的主光轴与第二透镜面112的交点与透镜110的主光轴与第一透射反射元件121的交点之间的间距)小于第二透射反射元件122与第一透射反射元件121之间的距离。例如，第二透镜面112的与第一透射反射元件121之间的间距 位于5毫米至15毫米之间。例如，第二透镜面112的与第一透射反射元件121之间的间距约为5.143毫米、8.304毫米、9.836毫米或13.153毫米。
例如，近眼显示装置100的出瞳101直径可以位于3毫米-5毫米之间(例如，4毫米)。例如，近眼显示装置100的出瞳位置(或出瞳距离)可以位于15毫米-30毫米(例如，16.384毫米、22.465毫米或28.021毫米)处。需要说明的是，近眼显示装置100的出瞳位置是指近眼显示装置100的最后一个光学面(也即，第一透射反射元件121)距离近眼显示装置100的出瞳101的距离(例如，沿第二透射反射元件122的主光轴的距离)。
例如，透镜110和光路折叠组件120的组合结构可被称为折返式光学系统，该折返式光学系统可以为同轴折返式光学系统，也即，透镜110的主光轴和第二透射反射元件122的主光轴在第一透射反射元件121的镜面反射面上相交。例如，通过使得透镜110和光路折叠组件120的组合结构为同轴折返式光学系统，可以保证近眼显示装置100显示的图像的画面质量。例如，同轴折返式光学系统还具有轻薄、视角大、成本低中的至少一个优点。例如，同轴折返式光学系统的具体结构和技术效果可参见相关技术，在此不再赘述。
为描述方便，可以将透镜110的主光轴和第二透射反射元件122的主光轴的交点记为第一交点。
例如，在优化折返式光学系统的过程中，在保证用户在出瞳101处可以观察到完整的第一图像的情况下，可以使得第二透射反射元件122的主光轴在第二透射反射元件122的顶点与第一交点之间长度尽可能的小，以使得近眼显示装置100的尺寸足够小。例如，第二透射反射元件122的主光轴在第二透射反射元件122的顶点与第一交点之间长度配置为使得微显示器140最边缘像素发射的光线可以顺次入射至第一透射反射元件121、第二透射反射元件122和第一透射反射元件121，然后从第一透射反射元件121穿过并入射至近眼显示系统的出瞳101，此种情况下，微显示器140显示的第一图像可以完整的成像在出瞳101处，也即，用户在出瞳101处可以观察到完整的第一图像，由此可以保证用户的使用体验。例如，如图2所示，第二透射反射元件122的主光轴在第二透射反射元件122的顶点与第一交点之间长度小于透镜110的第二透镜面112在第二方向D2上的长度。
图4示出了图1和图2所示的近眼显示装置100的场曲和畸变。如图4所示，在视场角(半视场)小于15度时，图1和图2所示的近眼显示装置100 的场曲小于±0.1毫米；在视场角(半视场)小于15度时，图1和图2所示的近眼显示装置100的为枕形畸变(对应地，基板取负值)，且枕型失真率小于5％。
图5示出了图1和图2所示的近眼显示装置100的调制传递函数(MTF)曲线。如图5所示，在视场角(半视场)为25度的情况下，MTF曲线如曲线181所示；在视场角(半视场)为23度的情况下，MTF曲线如曲线182所示。如图5所示，在视场角(半视场)为23度的情况下，用户可以分辨近眼显示装置100显示的图像中的具有高空间频率(例如，62线对/毫米)的信息(例如，细节信息)；在视场角(半视场)为25度的情况下，尽管用户不能很好的分辨近眼显示装置100显示的图像中的具有高空间频率的信息(例如，细节信息)，但是依然能够分别到近眼显示装置100显示的图像中的具有中低空间频率的信息(例如，轮廓信息)。因此，图1和图2所示的近眼显示装置100的视场角大于50度。例如，在对近眼显示装置100的体积的要求适当放宽的情况下，近眼显示装置100的视场角可以位于50度-90度之间，由此可以提升用户的使用体验。
综上，本公开的实施例提供的近眼显示装置100显示的图像满足用户对画面质量的需求。
在本公开的至少一个示例中，通过在保证用户在出瞳处可以观察到完整的第一图像的情况下，可以使得第二透射反射元件的主光轴在第二透射反射元件的顶点与第一交点之间长度尽可能的小，由此以使得近眼显示装置的尺寸足够小。此外，通过采用双非球面透镜提升近眼显示装置的画面质量，可以在近眼显示装置的尺寸足够小的情况下，使得近眼显示装置显示的画面满足用户的需求，由此可以提升用户的综合使用体验。
图6是本公开的至少一个实施例提供的另一种近眼显示装置200的结构示意图，图6示出的近眼显示装置200可以实现为单目式虚拟现实眼镜或双目式虚拟现实眼镜，图6示出的近眼显示装置200还可以实现为虚拟现实头盔或其它适用的虚拟现实显示装置。
如图6所示，该近眼显示装置200包括透镜210和光路折叠组件220。根据实际应用需求，如图6所示，该近眼显示装置200还包括微显示器240、偏光片232和1/4波片231。例如，透镜210和光路折叠组件220的组合结构可被称为折返式光学系统。
如图6所示，透镜210被配置为接收微显示器240投射的第一图像的投射光，且对第一图像进行整形(例如，放大第一图像)。在一些示例中，透镜210被配置为将第一图像放大至适合人眼观察的图像；在另一些示例中，透镜210与光路折叠组件220彼此配合以将第一图像放大至适合人眼观察的图像；在再一些示例中，透镜210还被配置为将第一图像的形状调整至适合人眼观察的图像，减小图像的畸变。
如图6所示，透镜210包括主光轴(图中未示出)以及在透镜210的主光轴所在的第一方向D1上对置的第一透镜面211和第二透镜面212，相比于第二透镜面212，第一透镜面211更靠近微显示器240。如图6所示，第一透镜面211和第二透镜面212均为非球面(例如，偶次非球面)，也即，本公开的至少一个实施例提供的透镜210双非球面透镜210。例如，透镜210的第一透镜面211的表面形状和第二透镜面212的表面形状、具体设置方式以及技术效果可以参见图1和图2所示的近眼显示装置200，在此不再赘述。
例如，通过采用双非球面透镜210提升近眼显示装置200的画面质量，可以通过优化光路折叠组件220，尽可能的降低近眼显示装置200的体积，由此可以提升用户的使用体验。
如图6所示，偏光片232在第一方向D1上位于透镜210的入光侧(也即，在第一方向D1上位于透镜210和微显示器240之间)，且配置为使得从偏光片232出射的偏振光为s-偏振光(s-L)。需要说明的是，本公开的至少一个实施例提供的偏光片232在第一方向D1上还可以位于透镜210的出光侧(也即，在第一方向D1上位于透镜210的远离微显示器240的一侧)。
如图6所示，光路折叠组件220被配置为接收由透镜210整形后的第一图像的光线，以及折叠从透镜210至近眼显示装置200的出瞳201的光路。例如，如图6所示，光路折叠组件220包括在与第一方向D1交叉的第二方向D2上对置的第一透射反射元件221和第二透射反射元件222。
例如，第一透射反射元件221为偏振分光元件，偏振分光元件对s-偏振光具有高反射率(例如，反射率大于90％，例如，100％)，且对p-偏振光具有高透射率(例如，透射率大于90％，例如，100％)。
例如，偏振分光元件的形状为平板状，以使得第一透射反射元件221和第二透射反射元件222可以形成一个中空的光学腔，由此可以减小光路折叠组件220和近眼显示装置200的重量，提高用户的使用体验。
例如，如图1和图2所示，第二透射反射元件222为曲面透射反射元件(例如，球面透射反射元件或非曲面透射反射元件)，由此，第二透射反射元件222也可以提供光焦度(focal power)，并可以用于与透镜210协作对第一图像进行整形，并因此，可以提升透镜210和光路折叠组件220的组合结构对第一图像的整形和整形效果。
例如，如图1和图2所示，第二透射反射元件222朝向近眼显示装置200的出瞳201的曲面为凹曲面。例如，第二透射反射元件222的主光轴与第二方向D2平行。例如，第一方向D1与第二方向D2垂直，也即，透镜210的主光轴与第二透射反射元件222的主光轴彼此垂直。例如，可选用相关的部分透射部分反射元件或镜片的制作材料制作第二透射反射元件222。例如，第二透射反射元件222可以包括多层介质薄膜。
如图6所示，1/4波片231在第二方向D2上设置在第一透射反射元件221和第二透射反射元件222之间，且第一图像的光线顺次由第一透射反射元件221反射、由1/4波片231透射、由第二透射反射元件222反射、由1/4波片231透射以及由第一透射反射元件221透射。
如图6所示，第一图像的光线(用于成像的第一图像的光线)的传输路径的描述如下。首先，第一图像的光线(s-偏振光s-L)入射至第一透射反射元件221，并被第一透射反射元件221反射；然后，第一图像的光线入射至1/4波片231，并穿过1/4波片231，并且，1/4波片231将第一图像的光线由s-偏振光s-L转变为圆偏振光c-L；接着，第一图像的光线(圆偏振光c-L)入射至第二透射反射元件222，并被第二透射反射元件222反射；第四，第一图像的光线(圆偏振光c-L)入射至1/4波片231，并穿过1/4波片231，并且，1/4波片231将第一图像的光线由圆偏振光c-L转变为p-偏振光p-L；第五，第一图像的光线(p-偏振光p-L)入射至第一透射反射元件221，并被第一透射反射元件221透射，第一图像的光线在穿过第一透射反射元件221后离开光路折叠组件220和近眼显示装置200。
例如，图6所示的近眼显示装置200的光利用效率η1可以使用以下的表达式进行表示：η1＝τ1×η11×η12×η13。此处，τ1为偏光片232对入射至偏光片232上的光线的透射率；η11为第一透射反射元件221对入射至第一透射反射元件221上的第一图像的光线的反射率；η12为第二透射反射元件222对入射至第二透射反射元件222上的第一图像的光线的反射率；η13为第一透射反 射元件221对入射至第一透射反射元件221上的第一图像的光线的透射率。例如，根据偏振分光元件和偏光片232的性质可知：τ1＝50％；η11＝100％；η13＝100％。在假设η12＝50％的情况下，η1＝50％×100％×50％×100％＝25％。例如，在提升第二透射反射元件222对入射至第二透射反射元件222上的第一图像的光线的反射率η12的情况下，可以使得近眼显示装置200的光利用效率η1提升至30％。
例如，图1和图2所示的近眼显示装置200的光利用效率η2可以使用以下的表达式进行表示：η2＝η21×η22×η23。此处，η21为第一透射反射元件221对入射至第一透射反射元件221上的第一图像的光线的反射率；η22为第二透射反射元件222对入射至第二透射反射元件222上的第一图像的光线的反射率；η23为第一透射反射元件221对入射至第一透射反射元件221上的第一图像的光线的透射率。例如，在假设第一透射反射元件221和第二透射反射元件222均为半透半反元件的情况下，η21、η22和η23均等于50％，因此，η2＝50％×50％×50％＝12.5％。例如，为了提升图1和图2所示的近眼显示装置200的光利用效率η2，可以在保证用户能够透过近眼显示装置200观察外部场景的情况下，适当提升第一透射反射元件221和第二透射反射元件222的反射率，尽管如此，近眼显示装置200的光利用效率η2可能难以超过20％。
综上所述，相比于图1和图2所示的近眼显示装置200，图6所示的近眼显示装置200的光利用效率得到了提升，因此可以降低近眼显示装置200的功耗以及续航时间，由此可以提升用户的使用体验。
图7是本公开的至少一个实施例提供的另一种近眼显示装置的另一种结构示意图。如图7所示，第一透射反射元件221的延长线和第二透射反射元件222的延长线的交点位于1/4波片231所在的平面，由此使得可以使得1/4波片231的通光孔径尽可能的大，因此可以进一步地提高图6和图7所示的近眼显示装置200的光利用效率。
例如，透镜210和光路折叠组件220的组合结构可被称为折返式光学系统可以为同轴折返式光学系统，也即，透镜210的主光轴和第二透射反射元件222的主光轴在第一透射反射元件221的镜面反射面上相交。为描述方便，可以将透镜210的主光轴和第二透射反射元件222的主光轴的交点记为第一交点。
例如，在优化折返式光学系统的过程中，在保证用户在出瞳201处可以 观察到完整的第一图像的情况下，可以使得第二透射反射元件222的主光轴在第二透射反射元件222的顶点与第一交点之间长度尽可能的小，以使得近眼显示装置200的尺寸足够小。例如，如图6所示，第二透射反射元件222的主光轴在第二透射反射元件222的顶点与第一交点之间长度小于透镜210的第二透镜面212在第二方向D2上的长度。
有以下几点需要说明，
(1)在本公开的至少一个实施例中，近眼显示装置的光利用效率是指经由第一透射反射元件离开光路折叠组件和近眼显示装置的光线的光强与微显示器发射的光线的光强的比值。
(2)考虑到1/4波片对光线的吸收可以忽略不计，因此，在计算图6所示的近眼显示装置的光利用效率η1过程中，假设1/4波片对第一图像的光线透射率为100％。
(3)在1/4波片的通光孔径满足应用需求的情况下，第一透射反射元件的延长线和第二透射反射元件的延长线的交点还可以与1/4波片所在的平面间隔设置(在第二方向D2上间隔设置)。
(4)在微显示器发射s-偏振光的情况下，近眼显示装置还可以不设置偏光片。
(5)图6所示的近眼显示装置的的体积和外观形状可以与图1和图2所示的近眼显示装置的体积和外观相同和相似。
(6)为清楚起见，在图6所示的近眼显示装置的实施例中，主要阐述了图6所示的近眼显示装置相比于图1和图2所示的近眼显示装置的不同之处，相同和相似之处可参见图1和图2所示的近眼显示装置的实施例。
在本公开的至少一个示例中，通过在保证用户在出瞳处可以观察到完整的第一图像的情况下，可以使得第二透射反射元件的主光轴在第二透射反射元件的顶点与第一交点之间长度尽可能的小，由此以使得近眼显示装置的尺寸足够小。此外，通过采用双非球面透镜提升近眼显示装置的画面质量，可以在近眼显示装置的尺寸足够小的情况下，使得近眼显示装置显示的画面满足用户的需求，由此可以提升用户的综合使用体验。此外，通过使用1/4波片和偏振分光元件，可以提升近眼显示装置的光利用效率，由此可以降低近眼显示装置的功耗以及续航时间，并可以进一步地提升用户的使用体验。
图8示出了本公开的至少一个实施例提供的一种双目式虚拟现实眼镜。 例如，本公开的实施例提供的近眼显示装置可以实现为图8示出的双目式虚拟现实眼镜。例如，如图2和图8所示，透镜和微显示器可以设置在虚拟现实眼镜的上部区域，相比于第二透射反射元件，第一透射反射元件更为靠近用户的眼睛。
例如，由于本公开的至少一个实施例提供的近眼显示装置降低了近眼显示装置的体积、重量、功耗的至少一个，并可以提升近眼显示装置的光利用率，由此使得本公开的至少一个实施例提供的近眼显示装置和双目式虚拟现实眼镜适合在日常生活中佩戴。
虽然上文中已经用一般性说明及具体实施方式，对本公开作了详尽的描述，但在本公开实施例基础上，可以对之作一些修改或改进，这对本领域技术人员而言是显而易见的。因此，在不偏离本公开精神的基础上所做的这些修改或改进，均属于本公开要求保护的范围。
以上所述仅是本公开的示范性实施方式，而非用于限制本公开的保护范围，本公开的保护范围由所附的权利要求确定。

Claims (15)

  1. 一种近眼显示装置，包括透镜和光路折叠组件，
    其中，所述透镜被配置为接收微显示器投射的第一图像的投射光，且对所述第一图像进行整形；
    所述透镜包括主光轴以及在所述透镜的主光轴所在的第一方向上对置的第一透镜面和第二透镜面，所述第一透镜面和所述第二透镜面均为非球面；以及
    所述光路折叠组件被配置为接收由所述透镜整形后的所述第一图像的光线，以及折叠从所述透镜至所述近眼显示装置的出瞳的光路。
  2. 根据权利要求1所述的近眼显示装置，其中，所述光路折叠组件包括在与所述第一方向交叉的第二方向上对置的第一透射反射元件和第二透射反射元件，且所述第一图像的光线顺次由所述第一透射反射元件反射、由所述第二透射反射元件反射以及由所述第一透射反射元件透射。
  3. 根据权利要求2所述的近眼显示装置，其中，所述第一透射反射元件为镜面透射反射元件。
  4. 根据权利要求2或3所述的近眼显示装置，其中，所述第二透射反射元件为曲面透射反射元件，且所述第二透射反射元件朝向所述近眼显示装置的出瞳的曲面为凹曲面。
  5. 根据权利要求2-4任一所述的近眼显示装置，其中，所述第二透射反射元件的主光轴与所述第二方向平行；
    所述透镜的主光轴和所述第二透射反射元件的主光轴在所述第一透射反射元件的镜面反射面上相交；以及
    所述第一透射反射元件的镜面反射面与所述第一方向的夹角等于45度。
  6. 根据权利要求2-5任一所述的近眼显示装置，其中，所述第一透射反射元件为偏振分光元件。
  7. 根据权利要求6所述的近眼显示装置，还包括1/4波片，其中，所述1/4波片在所述第二方向上设置在所述第一透射反射元件和所述第二透射反射元件之间，且所述第一图像的光线顺次由所述第一透射反射元件反射、由所述1/4波片透射、由所述第二透射反射元件反射、由所述1/4波片透射以及由所述第一透射反射元件透射。
  8. 根据权利要求7所述的近眼显示装置，其中，所述第一方向与所述第二方向垂直，所述第二方向垂直于所述1/4波片。
  9. 根据权利要求7或8所述的近眼显示装置，其中，所述第一透射反射元件的延长线和所述第二透射反射元件的延长线的交点位于所述1/4波片所在的平面。
  10. 根据权利要求6-9任一所述的近眼显示装置，还包括：
    偏光片，在所述第一方向上位于所述透镜的入光侧或出光侧，
    其中，所述偏光片配置为使得从所述偏光片出射的偏振光为s-偏振光；以及所述偏振分光元件配置为反射所述s-偏振光。
  11. 根据权利要求2-5任一所述的近眼显示装置，所述第一透射反射元件和所述第二透射反射元件的反射率均大于等于50％。
  12. 根据权利要求1-10任一所述的近眼显示装置，其中，相比于所述第二透镜面，所述第一透镜面更靠近所述微显示器；以及
    所述第一透镜面的曲率半径大于所述第二透镜面的曲率半径。
  13. 根据权利要求12所述的近眼显示装置，其中，所述第一透镜面和所述第二透镜面均为偶次非球面；
    所述透镜的第一透镜面的表面形状z满足以下的表达式(1)：
    Figure PCTCN2019125187-appb-100001
    所述透镜的第二透镜面的表面形状z满足以下的表达式(2)：
    Figure PCTCN2019125187-appb-100002
    z1为所述第一透镜面上任一点的相对于所述第一透镜面的顶点的切面的轴向间距；r1为所述第一透镜面上任一点相对于所述透镜的主光轴的径向距离；c1是所述第一透镜面的曲率，k1是所述第一透镜面的圆锥系数；a11、a12、a13、a14和a15分别是所述第一透镜面的二阶非球面系数、四阶非球面系数、六阶非球面系数、八阶非球面系数和十阶非球面系数；以及
    z2为所述第二透镜面上任一点的相对于所述第二透镜面的顶点的切面的轴向间距；r2为所述第二透镜面上任一点相对于所述透镜的主光轴的径向距离；c2是所述第二透镜面的曲率，k2是所述第二透镜面的圆锥系数；a21、a22、a23、a24和a25分别是所述第二透镜面的二阶非球面系数、四阶非球面系数、六阶非球面系数、八阶非球面系数和十阶非球面系数。
  14. 根据权利要求13所述的近眼显示装置，其中，a11、a12、a13、a14和a15分别满足以下范围：
    -0.9×10 -4＜a11＜1×10 -4
    -10×10 -3＜a12＜-1×10 -3
    1×10 -5＜a13＜10×10 -5
    -10×10 -9＜a14＜-1×10 -9
    -10×10 -10＜a15＜-1×10 -10
    a21、a22、a23、a24和a25分别满足以下范围：
    -0.9×10 -4＜a21＜1×10 -4
    1×10 -4＜a22＜10×10 -4
    -10×10 -6＜a23＜-1×10 -6。
    -10×10 -7＜a24＜-1×10 -7
    1×10 -10＜a25＜10×10 -10
  15. 根据权利要求1-14任一所述的近眼显示装置，还包括微显示器，其中，所述微显示器配置为朝向所述透镜投射所述第一图像的投射光。
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