WO2022088836A1 - 降低鬼影的显示光学系统及头戴显示装置 - Google Patents

降低鬼影的显示光学系统及头戴显示装置 Download PDF

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Publication number
WO2022088836A1
WO2022088836A1 PCT/CN2021/111747 CN2021111747W WO2022088836A1 WO 2022088836 A1 WO2022088836 A1 WO 2022088836A1 CN 2021111747 W CN2021111747 W CN 2021111747W WO 2022088836 A1 WO2022088836 A1 WO 2022088836A1
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Prior art keywords
conversion element
polarization conversion
lens
polarization
optical system
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PCT/CN2021/111747
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English (en)
French (fr)
Inventor
王旭
陈益千
于佳
张韦韪
Original Assignee
深圳惠牛科技有限公司
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Priority claimed from CN202011161123.5A external-priority patent/CN112305763A/zh
Priority claimed from CN202011160164.2A external-priority patent/CN112305762A/zh
Application filed by 深圳惠牛科技有限公司 filed Critical 深圳惠牛科技有限公司
Publication of WO2022088836A1 publication Critical patent/WO2022088836A1/zh

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
    • G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
    • G02B1/11—Anti-reflection coatings
    • 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 application relates to the field of optical display technology, and in particular, to a display optical system and a head-mounted display device that reduce ghosting.
  • NED Near eye display
  • HMD Head mounted display
  • the first is to coat the surface of the polarization control element with an AR (Anti-Reflection) layer or composite an optical film with AR function, but these materials can only have a low reflectivity near 589nm (such as ⁇ 0.7%, DNP LR Film), which cannot maintain good consistent performance over the entire visible light range.
  • the second is to combine a quarter wave plate QWP ( Quarter waveplate ) with a polarization beam splitter PBS (Polarization beam splitter), and then attach it to a substrate. This solution reduces an optical reflection surface, but the remaining optical Surface reflections are still evident, and corresponding ghosts dominate the imaging.
  • the third method is to combine QWP with PBS, and then attach it to the back surface of the lens, or attach it between the two lenses.
  • the corresponding reflection can be reduced, in order to meet the requirements of diopter and image quality, there are lenses in this solution. Unfavorable factors such as thicker thickness and increased weight limit its application in products.
  • the main purpose of this application is to propose a display optical system with reduced ghosting, which aims to reduce the ghosting caused by Fresnel reflection at the interface of different elements in the folded optical path exposed to the air, improve the image quality of the display optical system, and improve the quality of the display optical system. It has the characteristics of light weight.
  • the present application proposes a display optical system for reducing ghost images, including a display screen, a polarizer, a first polarization conversion element, a partial transmission and partial reflection element, a second polarization conversion element, and a polarization beam splitting element arranged in sequence.
  • the display optical system also includes a lens that is arranged on the side of the partially transmissive and partially reflective element away from the display screen; the lens and the second polarization conversion element are fitted and arranged, and/or, the lens and the polarized light splitting element are fitted and arranged; the second polarization conversion The element and the polarization beam splitting element are arranged at intervals, the surface of the second polarization conversion element exposed to the air is provided with a substrate, and an anti-reflection film is arranged on the substrate.
  • the lens is disposed between the partially transmissive and partially reflective element and the second polarization conversion element, the lens is attached to the partially transmissive and partially reflective element and the second polarization conversion element at the same time, and the second polarization conversion element and the polarization beam splitter element There is an air gap therebetween, and a substrate and an antireflection film are provided on the surface of the second polarization conversion element facing the polarization beam splitting element and the surface of the polarization beam splitter element facing the second polarization conversion element.
  • the surface of the substrate facing the second polarization conversion element has the same curvature as the surface of the substrate facing the polarization beam splitting element.
  • the surface of the substrate facing the second polarization converting element has the same curvature as the surface of the lens facing the second polarization converting element.
  • the surface of the substrate facing the second polarization converting element is flat.
  • the substrate has dispersive properties opposite to that of the lens.
  • optical glue is filled between the lens and the second polarization conversion element.
  • optical glue is filled between the second polarization conversion element and the substrate.
  • the optical glue uses an index matching material.
  • the present application also proposes a head-mounted display device for reducing ghost images, comprising: a head-mounted body; and the above-mentioned ghost-reducing display optical system, wherein the ghost-reducing display optical system is arranged in the head-mounted body .
  • the technical solution of the present application adopts a display screen, a polarizer, a first polarization conversion element, a partial transmission and a partial reflection element, a second polarization conversion element and a polarization beam splitting element arranged in sequence, and the lens is arranged on a part of the transmission and partial reflection element away from the display screen. side, the diopter superposition of the folded optical path can be realized.
  • the lens is attached to the second polarization conversion element, and/or the lens is attached to the polarization beam splitting element, so that the lens is in direct contact with one or two of the adjacent elements, that is, the lens and the adjacent elements attached to it.
  • the surface of the second polarization conversion element exposed to the air is provided with a substrate and an anti-reflection film on the substrate.
  • the substrate can significantly reduce the surface reflectivity, and the anti-reflection coating can have higher reliability, and the anti-reflection coating can reduce the ghost phenomenon caused by Fresnel reflection in one embodiment. Therefore, the application can greatly reduce the The ghost phenomenon caused by Fresnel reflection in the folded optical path improves the image quality of the display optical system.
  • the display optical system has the characteristics of light weight, can meet the weight requirements of the head-mounted display device, and is convenient for promotion and application in products.
  • the present invention also provides a display optical system for reducing ghost images, comprising a display screen, a polarization splitting element, a first polarization conversion element, a partial transmission and partial reflection element, a second polarization conversion element and a polarizer arranged in sequence; the display optical system It also includes a lens disposed on the side of the partially transmissive and partially reflective element facing the display screen; the lens is attached to the first polarization conversion element, and/or the lens is attached to the polarization splitting element; the first polarization conversion element is attached to the polarization splitting element.
  • the elements are arranged at intervals, the surface of the first polarization conversion element exposed to the air is provided with a substrate, and an anti-reflection film is arranged on the substrate.
  • the lens is disposed between the partially transmissive and partially reflective element and the first polarization conversion element, the lens is attached to the partially transmissive and partially reflective element and the first polarization conversion element at the same time, and the first polarization conversion element is attached to the polarization beam splitter.
  • the surface of the substrate facing the first polarization conversion element has the same curvature as the surface of the substrate facing the polarization beam splitting element.
  • the surface of the substrate facing the first polarization converting element has the same curvature as the surface of the lens facing the first polarization converting element.
  • the surface of the substrate facing the first polarization converting element is flat.
  • the substrate has dispersive properties opposite to that of the lens.
  • optical glue is filled between the lens and the first polarization conversion element.
  • optical glue is filled between the first polarization conversion element and the substrate.
  • the optical glue uses an index matching material.
  • the present invention also proposes a head-mounted display device for reducing ghost images, comprising: a head-mounted body; and the above-mentioned display optical system for reducing ghost images, wherein the display optical system for reducing ghost images is arranged in the head-mounted body .
  • the technical scheme of the present invention adopts a display screen, a polarization beam splitter element, a first polarization conversion element, a partially transmissive and partially reflective element, a second polarization conversion element and a polarizer arranged in sequence, and the lens is arranged on a part of the partially transmissive and partially reflective element facing the display screen.
  • the folding of the polarized light path can be realized.
  • the first polarization conversion element is attached to the lens, and/or the lens is attached to the polarization beam splitting element, so that the lens is in direct contact with one or two of the adjacent elements, that is, the lens and the adjacent elements attached to it.
  • the present invention can greatly reduce the folded optical path. The ghosting phenomenon caused by Fresnel reflection, thereby improving the image quality of the display optical system.
  • the display optical system has the characteristics of light weight, can meet the weight requirements of the head-mounted display device, and is convenient for promotion and application in products.
  • FIG. 1 is a schematic structural diagram of a basic folded optical path (the direction indicated by the arrow in the figure is the direction of the main image optical path);
  • FIG. 2 is a schematic structural diagram of an embodiment of a display optical system for reducing ghost images according to the present application (the direction indicated by the arrow in the figure is the direction of the remaining ghost image light path);
  • FIG 3 is a schematic structural diagram of another embodiment of the display optical system for reducing ghost images according to the present application (the direction indicated by the arrow in the figure is the direction of the remaining ghost image light path);
  • FIG. 4 is a schematic structural diagram of a lens and a second polarization conversion element in the display optical system for reducing ghosting in FIG. 3;
  • FIG. 5 is a schematic structural diagram of a lens, a second polarization conversion element and a substrate bonding in the display optical system for reducing ghost images in FIG. 3;
  • FIG. 6 is a schematic structural diagram of a lens, a second polarization conversion element and a substrate in another embodiment of the display optical system for reducing ghosting according to the present application;
  • FIG. 7 is a schematic structural diagram of a basic folded optical path (the direction indicated by the arrow in the figure is the direction of the main image optical path);
  • FIG. 8 is a schematic structural diagram of an embodiment of a display optical system for reducing ghost images according to the present invention (the direction indicated by the arrow in the figure is the direction of the remaining ghost image light path);
  • FIG. 9 is a schematic structural diagram of another embodiment of the display optical system for reducing ghost images according to the present invention (the direction indicated by the arrow in the figure is the direction of the remaining ghost image light path);
  • FIG. 10 is a schematic structural diagram of a lens and a first polarization conversion element in the display optical system for reducing ghosting in FIG. 9;
  • FIG. 11 is a schematic structural diagram of a lens, a first polarization conversion element and a substrate bonding in the display optical system for reducing ghost images in FIG. 9;
  • FIG. 12 is a schematic structural diagram of a lens, a first polarization conversion element and a substrate in another embodiment of the display optical system for reducing ghost images according to the present invention.
  • the present application proposes a display optical system 100 that reduces ghosting.
  • the display optical system for reducing ghost images includes a display screen 10 , a polarizer 20 , a first polarization conversion element 30 , a partially transmissive and partially reflective element arranged in sequence 90, the second polarization conversion element 50 and the polarization beam splitter element 60; the display optical system also includes a lens 40 arranged on the side of the partially transmissive and partially reflective element 90 away from the display screen; And/or, the lens 40 and the polarization beam splitting element 60 are attached and arranged; the second polarization conversion element 50 and the polarization beam splitter element 60 are arranged at intervals, and the surface of the second polarization conversion element 50 exposed to the air is provided with a substrate 70, and An anti-reflection film 71 is provided on the substrate 70 .
  • FIG. 1 shows a schematic structural diagram of a basic folded optical path (the direction indicated by the arrow in the figure is the direction of the main image optical path).
  • the basic folded optical path structure includes a polarizer 20 , a first polarization conversion element 30 , a partial transmission and partial reflection element 90 , a lens 40 , a second polarization conversion element 50 and a polarization beam splitter element 60 , which are arranged in sequence.
  • the polarizer 20 is preferably an absorbing polarizer, such as a PVA (polyvinyl alcohol, polyvinyl alcohol) polarizer commonly used in the display industry.
  • the first polarization conversion element 30 is a quarter wave plate QWP (quarter wave plate), the quarter wave plate can produce a quarter wavelength retardation between the fast and slow axis components of the incident polarized light,
  • the azimuth angle between the optical axis of the quarter-wave plate and the transmission axis of the polarizer is 40° to 50°, and further is 44° to 46°.
  • the lens 40 has a certain diopter, which can be a plano-convex lens, a biconvex lens or a meniscus lens with a positive focal length.
  • a biconvex lens 40 is preferred, that is, the lens 40 faces the first polarization conversion element 30
  • Both the surface of the lens 40 and the surface of the lens 40 facing the second polarization conversion element 50 are convex.
  • the partially transmissive and partially reflective element 90 can be provided separately from the lens 40, or can be attached to the surface of the lens 40 facing the screen, preferably attached to the side of the lens 40 facing the screen
  • the transmittance of the surface is 30% to 70%, and further 40% to 60%.
  • the second polarization conversion element 50 is specifically a quarter wave plate (QWP, quarter wave plate).
  • the material of the second polarization conversion element 50 may be the same as or different from that of the first polarization conversion element 30 , preferably the same as that of the first polarization conversion element 30 .
  • There are generally two directions of the optical axis of the second polarization conversion element 50 one is parallel to the first polarization conversion element 30 , and the other is perpendicular to the first polarization conversion element 30 .
  • the transmission axis of the polarization beam splitter element 60 (PBS, polarization beam splitter) is parallel to the polarizer 20, and when the second scheme is adopted, the transmission axis of the polarization beam splitter element 60 is perpendicular to the polarizer 20 .
  • the polarized light splitting element 60 can reflect the directly transmitted polarized light, so as to achieve the effect of folding the optical path.
  • a Bragg-type reflective polarizer can be selected, or a wire grid-type reflective polarizer can be selected.
  • the specific direction of the light is as follows: the light of the pixel on the display screen 10 is polarized into linear polarization by the polarizer 20, becomes circularly polarized after passing through the first polarization conversion element 30, and continues to pass through the second polarization After the conversion element 50 becomes linearly polarized again, the polarization direction is perpendicular to the transmission axis of the polarization beam splitter element 60, so it is reflected, and passes through the second polarization conversion element 50 for the second time, and the reflected light reaches the partially transmissive and partially reflective element At the same time, due to the half-wave loss caused by the reflection, the chirality of the circularly polarized light is reversed, causing the polarization state of the light after passing through the second polarization conversion element 50 for the third time to be the same as the first passing through the second polarization. Since the polarization states after the conversion element 50 are orthogonal, they can be transmitted by the polarization beam splitter
  • the lens 40 is arranged on the side of the partially transmissive and partially reflective element 90 away from the display screen; the lens 40 The second polarization conversion element 50 is attached and arranged, and/or, the lens 40 is attached to the polarization beam splitting element 60; The surface in the air is provided with a substrate 70 , and an anti-reflection film 71 is provided on the substrate 70 .
  • the above structure includes at least four situations:
  • the lens 40 is disposed between the partially transmissive and partially reflective element 90 and the second polarization conversion element 50 , the lens 40 is attached to the second polarization conversion element 50 , and the second polarization conversion element 50 faces the surface of the polarization beam splitter element 60 .
  • a substrate 70 and an antireflection film 71 are provided.
  • the lens 40 is arranged between the second polarization conversion element 50 and the polarization beam splitter element 60, the lens 40 and the second polarization conversion element 50 are attached and arranged, and the lens 40 and the polarization beam splitter element 60 are spaced apart, and the second polarization conversion element
  • the surface of the element 50 facing the first polarization conversion element 30 is provided with a substrate 70 and an antireflection film 71 .
  • the lens 40 is disposed between the second polarization conversion element 50 and the polarization beam splitter element 60, the lens 40 is attached to the second polarization conversion element 50 and the polarization beam splitter element 60 at the same time, and the second polarization conversion element 50 faces the first polarization conversion element 50.
  • the surface of the polarization conversion element 30 is provided with a substrate 70 and an antireflection film 71 .
  • the lens 40 is arranged on the side of the polarization beam splitter element 60 away from the second polarization conversion element 50, and the lens 40 is attached to the polarization beam splitter element 60;
  • the surface of the second polarization conversion element 50 facing the polarization beam splitting element 60 is provided with a substrate 70 and an antireflection film 71;
  • the surface of the element 50 facing the first polarization conversion element 30 is provided with a substrate 70 and an antireflection film 71 .
  • the interval between the second polarization conversion element 50 and the polarization beam splitter element 60 may be through the lens 40 or through the air.
  • an air gap is set between the second polarization conversion element 50 and the polarization beam splitter element 60 .
  • the lens 40 is attached to the second polarization conversion element 50 and the polarization beam splitter element 60 at the same time, the second polarization conversion element 50 and the polarization beam splitter element 60 are spaced by the lens 40 .
  • the lens 40 is attached to the second polarization conversion element 50 , or the lens 40 is attached to the polarization beam splitting element 60 , or the lens 40 is attached to the second polarization conversion element 50 and the polarization beam splitter element 60 at the same time.
  • the lens 40 is in direct contact with one or both of the adjacent elements, and there is no air isolation between the lens 40 and the adjacent elements attached to it, so the ghost image caused by the Fresnel reflection of the corresponding interface can be reduced .
  • a substrate 70 and an anti-reflection film 71 located on the substrate 70 are provided on the surface of the second polarization conversion element 50 exposed to the air.
  • the anti-reflection film 71 is also called an anti-reflection film, and its main function is to reduce optical The reflected light from the surface increases the light transmittance, thus reducing the ghosting phenomenon caused by Fresnel reflection in one embodiment.
  • the lens 40 and the second polarization conversion element 50 are attached and arranged, and/or the polarization beam splitter element 60 is attached and arranged, and the substrate 70 and the anti-reflection film 71 are arranged in accordance with the surface of the second polarization transformation element 50 exposed to the air. , which can greatly reduce the ghost phenomenon caused by Fresnel reflection, thereby improving the image quality of the display optical system.
  • an anti-reflection (AR) film is directly coated on the surface of the second polarization conversion element 50 facing the polarization beam splitter element 60, the surface reflection is usually between 0.5% and 1%, and the dispersion performance is poor, which is prone to obvious color cast. phenomenon, and at the same time can not get higher reliability.
  • a substrate 70 is added on the surface of the second polarization conversion element 50 facing the polarizing beam splitting element 60, and then an anti-reflection (AR) film is plated on the surface of the substrate 70 facing the polarizing beam splitting element 60, then the surface reflectance can be significantly reduced, say 0.3%, and have higher reliability. Therefore, compared with directly coating the anti-reflection film 71 on the surface of the second polarization conversion element 50, in this embodiment, the ghost image can be further reduced by 50%-70%, and the effect of reducing the ghost image is more obvious.
  • the present application does not limit the distance between any two elements among the display screen 10 , the polarizer 20 , the first polarization conversion element 30 , the partially transmissive and partially reflective element 90 , the lens 40 , and the polarization beam splitting element 60 . , which can be set according to actual needs.
  • the distance between the lens 40 and the polarization beam splitting element 60 can be determined according to the optical design of the main image. Therefore, the technical solution can meet the requirements of diopter adjustment and imaging quality in optical design, avoid unfavorable factors such as thick lens 40 and increased weight, and is suitable for promotion and application in products. Therefore, the display optical system 100 for reducing ghost images also has the characteristics of light weight, and can meet the weight requirements of the head mounted display (HMD) device.
  • HMD head mounted display
  • the display optical system for reducing ghost images includes a display screen 10 , a polarization beam splitting element 60 , and a first polarization conversion element arranged in sequence. 30.
  • the element 30 is attached and/or installed, and/or the lens 40 is attached to the polarization beam splitter element 60; the first polarization conversion element 30 and the polarization beam splitter element 60 are arranged at intervals, and the surface of the first polarization conversion element 30 exposed to the air is arranged
  • a substrate 70 is provided, and an anti-reflection film 71 is provided on the substrate 70 .
  • FIG. 7 shows a schematic structural diagram of a basic folded optical path (the direction indicated by the arrow in the figure is the direction of the main image optical path).
  • the basic folded optical path structure includes a display screen 10 , a polarization splitting element 60 , a first polarization conversion element 30 , a lens 40 , a partially transmissive and partially reflective element 90 , a second polarization conversion element 50 and a polarizer 20 arranged in sequence.
  • the polarization beam splitter 60 (PBS, polarization beam splitter) can be selected from a Bragg-type reflective polarizer or a wire-grid reflective polarizer.
  • the first polarization conversion element 30 is specifically a quarter wave plate (QWP, quarter wave plate), the quarter wave plate can produce a quarter wavelength retardation between the fast and slow axis components of the incident polarized light , under normal circumstances, the azimuth angle between the optical axis of the quarter-wave plate and the transmission axis of the polarization beam splitter element 60 is 40° ⁇ 50°, and further is 44° ⁇ 46°.
  • the lens 40 has a certain diopter, which can be a plano-convex lens, a biconvex lens or a meniscus lens with a positive focal length.
  • a biconvex lens 40 is preferred, that is, the lens 40 faces the first polarization conversion element 30
  • Both the surface of the lens 40 and the surface of the lens 40 facing the second polarization conversion element 50 are convex.
  • the partially transmissive and partially reflective element 90 (such as a beam splitter film, usually a transflective film) can be provided separately from the lens 40, or can be attached to the surface of the lens 40 away from the screen, preferably attached to the surface of the lens 40 away from the screen.
  • the second polarization conversion element 50 is specifically a quarter wave plate (QWP, quarter wave plate).
  • the material of the second polarization conversion element 50 may be the same as or different from that of the first polarization conversion element 30 , preferably the same as that of the first polarization conversion element 30 .
  • There are generally two directions of the optical axis of the second polarization conversion element 50 one is parallel to the first polarization conversion element 30 , and the other is perpendicular to the first polarization conversion element 30 .
  • the transmission axis of the polarizer 20 is parallel to the polarizing beam splitting element 60
  • the transmission axis of the polarizer 20 is perpendicular to the polarizing beam splitting element 60
  • the polarizer 20 is preferably an absorbing polarizer, such as a PVA (polyvinyl alcohol, polyvinyl alcohol) polarizer commonly used in the display industry.
  • PVA polyvinyl alcohol, polyvinyl alcohol
  • the polarizer 20 can absorb the polarized light of the straight-transmitting optical path and transmit the polarized light of the folded optical path, so as to achieve the effect of correctly displaying the main image of the folded optical path.
  • the specific direction of the light is as follows: the light of the pixel on the display screen 10 is polarized by the polarization beam splitting element 60 to be linearly polarized, and then becomes circularly polarized light after passing through the first polarization conversion element 30, reaching part of transmission and part of reflection When the element 90 is reflected, it passes through the first polarization conversion element 30 for the second time. Due to the half-wave loss caused by the reflection, the chirality of the circularly polarized light is reversed.
  • the polarization direction is parallel to
  • the polarization direction is parallel to the transmission axis of the polarizer 20 , so that the main image can be transmitted through.
  • the lens 40 is arranged on the side of the partially transmissive and partially reflective element 90 facing the display screen; the lens 40 The first polarization conversion element 30 is attached and arranged, and/or the lens 40 is attached to the polarization beam splitting element 60; The surface in the air is provided with a substrate 70 , and an anti-reflection film 71 is provided on the substrate 70 .
  • the above structure includes at least four situations:
  • the lens 40 is disposed between the partially transmissive and partially reflective element 90 and the first polarization conversion element 30 , the lens 40 and the second polarization conversion element 50 are attached and disposed, and the first polarization conversion element 30 faces the surface of the polarization beam splitter element 60 .
  • a substrate 70 and an antireflection film 71 are provided.
  • the lens 40 is arranged between the first polarization conversion element 30 and the polarization beam splitter element 60 , the lens 40 and the first polarization conversion element 30 are attached and arranged, and the lens 40 and the polarization beam splitter element 60 are arranged at intervals, and the first polarization conversion element
  • the surface of the element 30 facing the first polarization conversion element 30 is provided with a substrate 70 and an antireflection film 71 .
  • the lens 40 is arranged between the first polarization conversion element 30 and the polarization beam splitter element 60, the lens 40 is attached to the first polarization conversion element 30 and the polarization beam splitter element 60 at the same time, and the first polarization conversion element 30 faces the first polarization conversion element 30 and the polarization beam splitter element 60.
  • the surface of the polarization conversion element 30 is provided with a substrate 70 and an antireflection film 71 .
  • the lens 40 is arranged on the side of the polarization beam splitter element 60 away from the first polarization conversion element 30, and the lens 40 is attached to the polarization beam splitter element 60;
  • the substrate 70 and the anti-reflection film 71 are provided on the surface of the first polarization conversion element 30 facing the polarization beam splitting element 60;
  • the first polarization conversion element 30 is attached to the polarization beam splitter element 60, the The surface of the element 30 facing the first polarization conversion element 30 is provided with a substrate 70 and an antireflection film 71 .
  • the first polarization conversion element 30 and the polarization splitting element 60 are spaced apart, which may be spaced by the lens 40 or spaced by air.
  • an air gap is set between the first polarization conversion element 30 and the polarization beam splitter element 60 .
  • the lens 40 is attached to the first polarization conversion element 30 and the polarization beam splitter element 60 at the same time, the first polarization conversion element 30 and the polarization beam splitter element 60 are spaced by the lens 40 .
  • the lens 40 is attached to the first polarization conversion element 30 , or the lens 40 is attached to the polarization beam splitter element 60 , or the lens 40 is attached to the first polarization conversion element 30 and the polarization beam splitter element 60 at the same time.
  • the lens 40 is in direct contact with one or both of the adjacent elements, and there is no air isolation between the lens 40 and the adjacent elements attached to it, so the ghost image caused by the Fresnel reflection of the corresponding interface can be reduced .
  • a substrate 70 and an anti-reflection film 71 located on the substrate 70 are provided on the surface of the first polarization conversion element 30 exposed to the air.
  • the anti-reflection film 71 is also called an anti-reflection film, and its main function is to reduce optical The reflected light from the surface increases the light transmittance, which can further reduce the ghosting phenomenon caused by Fresnel reflection.
  • the lens 40 and the first polarization conversion element 30 are attached to each other, and/or the polarization beam splitter element 60 is attached to each other, and the substrate 70 and the anti-reflection film 71 are arranged in accordance with the surface of the first polarization conversion element 30 exposed to the air. , which can greatly reduce the ghost phenomenon caused by Fresnel reflection, thereby improving the image quality of the display optical system.
  • an anti-reflection (AR) film is directly coated on the surface of the first polarization conversion element 30 facing the polarization beam splitter element 60, the surface reflection is usually between 0.5% and 1%, and the dispersion performance is poor, which is prone to obvious color cast. phenomenon, and at the same time can not get higher reliability.
  • a substrate 70 is added on the surface of the first polarization conversion element 30 facing the polarizing beam splitting element 60, and then an anti-reflection (AR) film is plated on the surface of the substrate 70 facing the polarizing beam splitting element 60, then the surface reflectance can be significantly reduced, say 0.3%, and have higher reliability. Therefore, compared with directly coating the anti-reflection film 71 on the surface of the first polarization conversion element 30, in this embodiment, the ghost image can be further reduced by 50%-70%, and the effect of reducing the ghost image is more obvious.
  • the present invention does not limit the distance between any two elements among the display screen 10 , the polarization beam splitting element 60 , the first polarization conversion element 30 , the partially transmissive and partially reflective element 90 , the lens 40 , and the polarizer 20 . , which can be set according to actual needs.
  • the distance between the lens 40 and the polarization beam splitting element 60 can be determined according to the optical design of the main image. Therefore, the technical solution can meet the requirements of diopter adjustment and imaging quality in optical design, avoid unfavorable factors such as thick lens 40 and increased weight, and is suitable for promotion and application in products. Therefore, the display optical system 100 for reducing ghost images also has the characteristics of light weight, and can meet the weight requirements of the head mounted display (HMD) device.
  • HMD head mounted display
  • the lens 40 is disposed between the partially transmissive and partially reflective element 90 and the second polarization conversion element 50 , and the lens 40 is simultaneously connected to the partially transmissive and partially reflective element 90 and the second polarization conversion element 50 .
  • the conversion element 50 is attached and installed, there is an air gap between the second polarization conversion element 50 and the polarization beam splitter element 60, the second polarization conversion element 50 faces the surface of the polarization beam splitter element 60, and the polarization beam splitter element 60 faces the surface of the second polarization conversion element 50.
  • a substrate 70 and an anti-reflection film 71 are provided on both surfaces.
  • the remaining ghost light path formed by the interface reflection on the back surface of the substrate 70 (that is, toward the polarization beam splitting element 60 ) is shown in FIG. 2 , and its ratio to the main image is RR p cos 2 ⁇ , where R is The reflectivity of the partially transmissive and partially reflective element 90, Rp is the reflectivity of the polarization beam splitter element 60 in the transmission axis direction, and cos ⁇ is the light leakage caused by the retardation of the second polarization conversion element 50 deviating from a quarter of the optical path.
  • the lens 40 is in direct contact with the partially transmissive and partially reflective element 90 , and the lens 40 is in direct contact with the second polarization conversion element 50 . Then, between the lens 40 and the partially transmissive and partially reflective element 90 , and between the lens 40 and the second polarization conversion element 90 There is no air isolation between the conversion elements 50, which can reduce the ghost image caused by the Fresnel reflection of the corresponding interface; at the same time, the surface of the second polarization conversion element 50 exposed to the air (ie the surface facing the polarization beam splitter element 60) and The surface of the polarizing beam splitter element 60 exposed to the air (that is, the surface facing the second polarization conversion element 50 ) is provided with a substrate 70 and an anti-reflection film 71.
  • the substrate 70 can significantly reduce the surface reflectivity and make the anti-reflection film. 71 has higher reliability, and the anti-reflection coating 71 can reduce the ghost phenomenon caused by Fresnel reflection in one embodiment, thereby improving the image quality of the display optical system.
  • the distance between the lens 40 and the polarizing beam splitting element 60 can be determined according to the optical design of the main image, so as to meet the requirements of diopter adjustment and imaging image quality of the optical design.
  • the lens 40 is disposed between the partially transmissive and partially reflective element 90 and the first polarization conversion element 30 , and the lens 40 is simultaneously connected to the partially transmissive and partially reflective element 90 and the first polarization conversion element 30 .
  • the conversion elements 30 are attached to each other, there is an air gap between the first polarization conversion element 30 and the polarization beam splitter element 60 , the first polarization conversion element 30 faces the surface of the polarization beam splitter element 60 , and the polarization beam splitter element 60 faces the surface of the first polarization conversion element 30 .
  • a substrate 70 and an anti-reflection film 71 are provided on both surfaces.
  • the remaining ghost light path formed by the interface reflection on the front surface of the substrate 70 (that is, toward the polarization beam splitting element 60 ) is shown in FIG. 8 , and its ratio to the main image is RR p cos 2 ⁇ , where R is The reflectivity of the partially transmissive and partially reflective element 90, Rp is the reflectivity of the polarization beam splitting element 60 in the transmission axis direction, and cos ⁇ is the light leakage caused by the retardation of the first polarization conversion element 30 deviating from a quarter of the optical path.
  • the lens 40 is in direct contact with the partially transmissive and partially reflective element 90 , and the lens 40 is in direct contact with the first polarization conversion element 30 . Then, between the lens 40 and the partially transmissive and partially reflective element 90 , and between the lens 40 and the first polarization conversion element 90 There is no air isolation between the conversion elements 30, which can reduce the ghost image caused by the Fresnel reflection of the corresponding interface.
  • the surface of the first polarization conversion element 30 exposed to the air (ie the surface facing the polarization beam splitting element 60 ) and the surface of the polarization beam splitter element 60 exposed to the air (ie the surface facing the first polarization conversion element 30 ) are provided with Substrate 70 and anti-reflection film 71, the substrate 70 can significantly reduce the surface reflectivity, and make the anti-reflection film 71 have higher reliability, and the anti-reflection film 71 can further reduce the ghost phenomenon caused by Fresnel reflection , thereby improving the image quality of the display optical system.
  • the distance between the lens 40 and the polarizing beam splitting element 60 can be determined according to the optical design of the main image, so as to meet the requirements of diopter adjustment and imaging image quality of the optical design.
  • the curvature of the surface of the substrate 70 facing the second polarization conversion element 50 is the same as the curvature of the surface of the substrate 70 facing the polarization beam splitting element 60 .
  • the substrate 70 has no optical power, that is, the curvatures of the front and rear surfaces of the substrate 70 are the same, so the direction of the light in the original optical path structure will not be affected, thereby ensuring the normal operation of the original optical path structure and the original optical path structure.
  • the curvature of the surface of the substrate 70 facing the first polarization conversion element 30 is the same as the curvature of the surface of the substrate 70 facing the polarization beam splitting element 60 .
  • the substrate 70 has no optical power, that is, the curvatures of the front and rear surfaces of the substrate 70 are the same, so the direction of the light in the original optical path structure will not be affected, thereby ensuring the normal operation of the original optical path structure and the original optical path structure.
  • the curvature of the surface of the substrate 70 facing the second polarization converting element 50 is the same as the curvature of the surface of the lens 40 facing the second polarization converting element 50 .
  • the second polarization conversion element 50 (for example, a quarter-wave plate) can be composed of crystal, polymer stretching, liquid crystal coating, etc., preferably a film form such as polymer stretching and liquid crystal coating, for convenience Fits the curved surfaces of lenses with different radii of curvature.
  • the second polarization conversion element 50 can adapt to the shape of the lens 40 .
  • the curvature of the front and rear surfaces of the substrate 70 is also the same as the curvature of the rear surface of the lens 40 (that is, the surface facing the second polarization conversion element 50 ).
  • the second polarization conversion element 50 is well glued together, and will not affect the direction of the light in the original optical path structure, so as to ensure the imaging quality.
  • the curvature of the surface of the substrate 70 facing the first polarization converting element 30 is the same as the curvature of the surface of the lens 40 facing the first polarization converting element 30 .
  • the first polarization conversion element 30 (for example, a quarter-wave plate) can be composed of crystal, polymer stretching, liquid crystal coating, etc., preferably a film form such as polymer stretching and liquid crystal coating, for convenience Fits the curved surfaces of lenses with different radii of curvature.
  • the first polarization conversion element 30 can adapt to the shape of the lens 40 .
  • the curvature of the front and rear surfaces of the substrate 70 is also the same as the curvature of the rear surface of the lens 40 (that is, the surface facing the first polarization conversion element 30 ).
  • the first polarization conversion elements 30 are well glued together, and will not affect the direction of the light in the original optical path structure, so as to ensure the imaging quality.
  • the surface of the substrate 70 facing the second polarization conversion element 50 is flat.
  • the substrate 70 can be considered as a plane element, that is, the front and rear surfaces (that is, the substrate 70 )
  • the surfaces toward the second polarization conversion element 50 and toward the polarization beam splitter element 60) are both flat surfaces.
  • the edge gap is less than 0.5mm, which is convenient for filling and curing of optical glue.
  • Optical glue is preferably made of refractive index matching material.
  • the combined lens is equivalent to a lens formed by an index matching material and the lens 40 is cemented. In this way, the effect of reducing ghost images can also be achieved. This structure can reduce the difficulty of the process and the manufacturing cost, but the influence brought by the cemented lens needs to be considered in the imaging design.
  • the surface of the substrate 70 facing the first polarization conversion element 30 is flat.
  • the substrate 70 can be considered as a plane element, that is, the front and rear surfaces of the substrate 70 (that is, the substrate 70 )
  • the surfaces toward the first polarization conversion element 30 and toward the polarization beam splitter element 60) are both flat surfaces.
  • the edge gap is less than 0.5mm, which is convenient for filling and curing of optical glue.
  • Optical glue is preferably made of refractive index matching material.
  • the combined lens is equivalent to a lens formed by an index matching material and the lens 40 is cemented. In this way, the effect of reducing ghost images can also be achieved. This structure can reduce the difficulty of the process and the manufacturing cost, but the influence brought by the cemented lens needs to be considered in the imaging design.
  • the substrate 70 has dispersive properties opposite to those of the lens 40 .
  • the substrate 70 can additionally correct the chromatic aberration of the system without affecting the existing optical performance by selecting appropriate materials.
  • the substrate 70 of the flat plate type or without diopter that is, the curvature of the front and rear surfaces is the same
  • its positional chromatic aberration is positive chromatic aberration, which is related to the refractive index, thickness and Abbe number
  • the convex lens 40 has negative positional chromatic aberration
  • appropriate materials and thicknesses can be selected based on the corresponding chromatic aberration calculation formulas, such as primary Seidel aberration and advanced chromatic aberration, so that the display optical system has a more ideal chromatic aberration performance.
  • the chromatic aberration of the lens 40 is compensated by the substrate 70 having the opposite dispersion characteristic to that of the lens 40, so that the chromatic aberration can be effectively eliminated.
  • the optical glue 80 is filled between the lens 40 and the second polarization conversion element 50 .
  • Optical adhesive 80 is a special adhesive for bonding transparent optical parts. It is required to be colorless and transparent, light transmittance above 90%, good bonding strength, and can be cured at room temperature or medium temperature. Curing shrinkage and other characteristics. Silicone, acrylic resin and unsaturated polyester, polyurethane, epoxy resin and other adhesives can be used to bond optical parts.
  • Optical glue 80 is a kind of macromolecular substance with similar optical properties to optical parts and excellent bonding properties.
  • the optical glue 80 can be selectively coated on the rear surface of the lens 40 (ie, the surface facing the second polarization conversion element 50 ), or can be selectively coated on the front surface of the second polarization conversion element 50 (ie, the surface facing the lens 40 ) It is preferable to coat on the second polarization conversion element 50, because the second polarization conversion element 50 (such as a quarter-wave plate) is soft as a whole. Before the second polarization conversion element 50 is attached to the lens 40, the first The two polarization conversion elements 50 can be in a plane state.
  • the second polarization conversion element 50 is attached to the rear surface of the lens 40 and adapted to the convex shape of the lens 40 , can achieve better uniformity and flatness.
  • the optical glue 80 is filled between the lens 40 and the first polarization conversion element 30 .
  • Optical adhesive 80 is a special adhesive for bonding transparent optical parts. It is required to be colorless and transparent, light transmittance above 90%, good bonding strength, and can be cured at room temperature or medium temperature. Curing shrinkage and other characteristics. Silicone, acrylic resin and unsaturated polyester, polyurethane, epoxy resin and other adhesives can be used to bond optical parts.
  • Optical glue 80 is a kind of macromolecule material with similar optical properties to optical parts and excellent bonding properties.
  • the optical glue 80 can be selectively coated on the rear surface of the lens 40 (that is, the surface facing the first polarization conversion element 30 ), or can be selectively coated on the front surface of the first polarization converting element 30 (that is, the surface facing the lens 40 ) It is preferable to coat on the first polarization conversion element 30, because the first polarization conversion element 30 (such as a quarter-wave plate) is soft as a whole. Before the first polarization conversion element 30 is attached to the lens 40, the A polarization conversion element 30 can be in a planar state. After the optical glue 80 is coated on the front surface of the first polarization conversion element 30, the first polarization conversion element 30 is attached to the rear surface of the lens 40 and adapted to the convex shape of the lens 40.
  • a vacuum defoaming operation needs to be performed by a defoaming machine, so as to avoid the scattering of the imaging light caused by residual air bubbles in the gap between the first polarization conversion element 30 and the lens 40 when they are glued.
  • the optical glue 80 is filled between the second polarization conversion element 50 and the substrate 70 .
  • the second polarization conversion element 50 and the substrate 70 are also glued together by the optical glue 80 .
  • the optical adhesive 80 can be selectively coated on the front surface of the substrate 70 (that is, the surface facing the second polarization conversion element 50 ), or can be selectively coated on the rear surface of the second polarization converting element 50 (that is, the surface facing the polarization beam splitting element 60 ).
  • the surface of the second polarization conversion element 50 is preferably coated on the back surface of the second polarization conversion element 50, because the second polarization conversion element 50 (such as a quarter-wave plate) is soft as a whole, and the second polarization conversion element 50 is attached to the Before the lens 40, the second polarization conversion element 50 can be in a plane state.
  • the second polarization conversion element 50 is attached to the rear surface of the lens 40, and the second polarization conversion element 50 is attached.
  • the substrate 70 By adapting to the convex shape of the lens 40 , and finally attaching the substrate 70 to the rear surface of the second polarization conversion element 50 , better uniformity and flatness can be achieved.
  • optical glue 80 is filled between the first polarization conversion element 30 and the substrate 70 .
  • the first polarization conversion element 30 and the substrate 70 are also glued together by the optical glue 80 .
  • the optical adhesive 80 can be selectively coated on the front surface of the substrate 70 (that is, the surface facing the first polarization conversion element 30 ), or can be selectively coated on the rear surface of the first polarization converting element 30 (that is, the surface facing the polarization beam splitting element 60 ).
  • the surface of the first polarization conversion element 30 is preferably coated on the back surface of the first polarization conversion element 30, because the first polarization conversion element 30 (such as a quarter-wave plate) is soft as a whole, and is attached to the first polarization conversion element 30. Before the lens 40, the first polarization conversion element 30 can be in a plane state.
  • the first polarization conversion element 30 is attached to the rear surface of the lens 40, and the optical glue 80 is applied.
  • Adapting to the convex shape of the lens 40 , and finally attaching the substrate 70 to the rear surface of the first polarization conversion element 30 better uniformity and flatness can be achieved.
  • a vacuum defoaming operation needs to be performed by a defoaming machine, so as to avoid the scattering of the imaging light caused by residual air bubbles in the gap between the first polarization conversion element 30 and the substrate 70 when they are glued.
  • the optical glue 80 uses a refractive index matching material.
  • the meaning of matching here is to reduce the refractive index difference between the materials on both sides of the interface, thereby minimizing the loss of reflected light.
  • Refractive index matching is an important means of optics, and its purpose is to make the refractive index of the contacting substances conform to a certain law, so as to reduce the reflection of light or increase the transmission of light.
  • refractive index matching materials By selecting refractive index matching materials, the interface reflection inside the optical system can be reduced, thereby reducing ghost images and improving image quality.
  • the material of the substrate 70 is glass, resin or optical film.
  • the material of the substrate 70 is preferably glass. It can be seen from the coating process that high temperature can usually achieve better coating effect, because when the substrate is pretreated, it first plays the role of activation, which increases the chemical bonding force between the substrate and the film material, and improves the bonding between the film layer and the substrate.
  • some low-refractive materials such as magnesium fluoride (MgF2) used as AR coating 71 are only suitable for high temperature deposition, while glass usually has better high temperature resistance Therefore, compared with resin and optical film, the substrate 70 is made of glass material, which can achieve lower interface reflection and better film reliability.
  • MgF2 magnesium fluoride
  • the present application also proposes a ghost-reducing head-mounted display device, the ghost-reducing head-mounted display device includes a head-mounted body and a ghost-reducing display optical system 100, and the ghost-reducing display optical system 100 is provided on the head-mounted display
  • the specific structure of the display optical system 100 for reducing ghost images refers to the above-mentioned embodiments. Since this head-mounted display device for reducing ghost images adopts all the technical solutions of all the above-mentioned embodiments, it has at least the technical solutions of the above-mentioned embodiments. All the beneficial effects brought about will not be repeated here.
  • the head-mounted body may include a frame suitable for wearing on the user's head, an elastic adjustment device for adjusting the degree of restraint of the frame, and a control system connected with the display optical system to control the display screen 10, and the like.
  • the specific structure and setting may adopt the prior art, which will not be repeated here.

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Abstract

本申请公开一种降低鬼影的显示光学系统及头戴显示装置，其中，降低鬼影的显示光学系统，包括依序设置的显示屏、偏振件、第一偏振转换元件、部分透射部分反射元件、第二偏振转换元件和偏振分光元件；显示光学系统还包括设置于部分透射部分反射元件背离显示屏的一侧的透镜；透镜与第二偏振转换元件贴合设置，和/或，透镜与偏振分光元件贴合设置；第二偏振转换元件与偏振分光元件之间间隔设置，第二偏振转换元件暴露于空气中的表面设置有基片，且基片上设置有增透膜。

Description

降低鬼影的显示光学系统及头戴显示装置
本申请要求于2020年10月26日提交中国专利局、申请号为202011161123.5、申请名称为“降低鬼影的显示光学系统及头戴显示装置”的中国专利申请的优先权以及于2020年10月26日提交中国专利局、申请号为202011160164.2、申请名称为“降低鬼影的显示光学系统及头戴显示装置”的中国专利申请的优先权，其全部内容通过引用结合在申请中。
技术领域
本申请涉及光学显示技术领域，特别涉及一种降低鬼影的显示光学系统及头戴显示装置。
背景技术
在近眼显示NED(Near eye display)或头戴显示HMD(Head mounted display)光学系统中，光学膜材(optical film)因为其功能性和高性价比，应用越来越广泛，比如偏振控制元件、偏光片、补偿片等，在折叠光路(pancake)中发挥重要的作用。但是，这些元件暴露在空气中会产生菲涅尔反射(指当光入射到折射率不同的两个媒质分界面时，一部分光会被反射的现象)，进而产生鬼影，影响图像质量。
现主要有三种思路来解决该问题。第一种是在偏振控制元件的表面涂布AR(Anti-Reflection)层或者复合一层具有AR功能的光学薄膜，但是这些材料仅能在589nm附近具有较低的反射率(比如<0.7％，DNP LR Film)，无法做到在整个可见光范围内保持较好的一致性能。第二种是将四分之一波片QWP( Quarter waveplate)与偏振光分束器PBS(Polarization beam splitter)复合，然后贴合在一基片上，该方案减少了一个光学反射面，但是剩余光学面的反射仍然明显，并且相应的鬼影在成像中占据主要作用。第三种则是把QWP与PBS复合后，同时贴合在透镜后表面，或者贴合在两个透镜之间，虽然可以降低相应反射，但该方案为了满足屈光度和像质的要求，存在透镜较厚、重量上升等不利因素，限制了其在产品中的应用。
申请内容
本申请的主要目的是提出一种降低鬼影的显示光学系统，旨在降低折叠光路中不同元件的界面暴露在空气中产生菲涅尔反射造成的鬼影，提高显示光学系统的图像质量，并具有轻量化的特点。
为实现上述目的，本申请提出一种降低鬼影的显示光学系统，包括依序设置的显示屏、偏振件、第一偏振转换元件、部分透射部分反射元件、第二偏振转换元件和偏振分光元件；显示光学系统还包括设置于部分透射部分反射元件背离显示屏的一侧的透镜；透镜与第二偏振转换元件贴合设置，和/或，透镜与偏振分光元件贴合设置；第二偏振转换元件与偏振分光元件之间间隔设置，第二偏振转换元件暴露于空气中的表面设置有基片，且基片上设置有增透膜。
在一个实施例中，透镜设置于部分透射部分反射元件与第二偏振转换元件之间，透镜同时与部分透射部分反射元件和第二偏振转换元件贴合设置，第二偏振转换元件与偏振分光元件之间存在空气间隔，第二偏振转换元件朝向偏振分光元件的表面、偏振分光元件朝向第二偏振转换元件的表面上均设置有基片和增透膜。
在一个实施例中，基片朝向第二偏振转换元件的表面的曲率和基片朝向偏振分光元件的表面的曲率相同。
在一个实施例中，基片朝向第二偏振转换元件的表面的曲率与透镜朝向第二偏振转换元件的表面的曲率相同。
在一个实施例中，基片朝向第二偏振转换元件的表面为平面。
在一个实施例中，基片具有与透镜相反的色散特性。
在一个实施例中，透镜和第二偏振转换元件之间填充有光学胶。
在一个实施例中，第二偏振转换元件和基片之间填充有光学胶。
在一个实施例中，光学胶采用折射率匹配材料。
为实现上述目的，本申请还提出一种降低鬼影的头戴显示装置，包括：头戴主体；及上述的降低鬼影的显示光学系统，降低鬼影的显示光学系统设于头戴主体内。
本申请技术方案采用显示屏、偏振件、第一偏振转换元件、部分透射部分反射元件、第二偏振转换元件和偏振分光元件依序设置，且透镜设置于部分透射部分反射元件背离显示屏的一侧，能够实现折叠光路的屈光度叠加。通过透镜与第二偏振转换元件贴合设置，和/或，透镜与偏振分光元件贴合设置，使透镜与相邻元件中的一个或两个直接接触，即透镜和与之贴合的相邻元件之间没有空气隔离，从而可以减少相应界面的菲涅尔反射带来的鬼影；同时，通过在第二偏振转换元件暴露于空气中的表面设置有基片以及位于基片上的增透膜，基片可以使表面反射率显著降低，并且使增透膜具有更高的可靠性，增透膜可以在一个实施例中降低菲涅尔反射产生的鬼影现象，因此，本申请可以大幅降低折叠光路中因菲涅尔反射产生的鬼影现象，从而提高显示光学系统的图像质量。而且，因为透镜和偏振分光元件之间的距离可以根据实际需求进行调整，以满足光学设计的屈光度和像质的要求，因而可以避免透镜较厚、重量上升等不利因素，故本降低鬼影的显示光学系统具有轻量化的特点，能够满足头戴显示装置对重量的要求，便于在产品中推广应用。
本发明还提出一种降低鬼影的显示光学系统，包括依序设置的显示屏、偏振分光元件、第一偏振转换元件、部分透射部分反射元件、第二偏振转换元件和偏振件；显示光学系统还包括设置于部分透射部分反射元件朝向显示屏的一侧的透镜；透镜与第一偏振转换元件贴合设置，和/或，透镜与偏振分光元件贴合设置；第一偏振转换元件与偏振分光元件之间间隔设置，第一偏振转换元件暴露于空气中的表面设置有基片，且基片上设置有增透膜。
在一个实施例中，透镜设置于部分透射部分反射元件与第一偏振转换元件之间，透镜同时与部分透射部分反射元件和第一偏振转换元件与贴合设置，第一偏振转换元件与偏振分光元件之间存在空气间隔，第一偏振转换元件朝向偏振分光元件的表面、偏振分光元件朝向第一偏振转换元件的表面上均设置有基片和增透膜。
在一个实施例中，基片朝向第一偏振转换元件的表面的曲率和基片朝向偏振分光元件的表面的曲率相同。
在一个实施例中，基片朝向第一偏振转换元件的表面的曲率与透镜朝向第一偏振转换元件的表面的曲率相同。
在一个实施例中，基片朝向第一偏振转换元件的表面为平面。
在一个实施例中，基片具有与透镜相反的色散特性。
在一个实施例中，透镜和第一偏振转换元件之间填充有光学胶。
在一个实施例中，第一偏振转换元件和基片之间填充有光学胶。
在一个实施例中，光学胶采用折射率匹配材料。
为实现上述目的，本发明还提出一种降低鬼影的头戴显示装置，包括：头戴主体；及上述的降低鬼影的显示光学系统，降低鬼影的显示光学系统设于头戴主体内。
本发明技术方案采用显示屏、偏振分光元件、第一偏振转换元件、部分透射部分反射元件、第二偏振转换元件和偏振件依序设置，且透镜设置于部分透射部分反射元件朝向显示屏的一侧，能够实现偏振光路的折叠。通过第一偏振转换元件与透镜贴合设置，和/或，透镜与偏振分光元件贴合设置，使透镜与相邻元件中的一个或两个直接接触，即透镜和与之贴合的相邻元件之间没有空气隔离，从而可以减少相应界面的菲涅尔反射带来的鬼影；同时，通过在第一偏振转换元件暴露于空气中的表面设置有基片以及位于基片上的增透膜，基片可以使表面反射率显著降低，并且使增透膜具有更高的可靠性，增透膜可以进一步地降低菲涅尔反射产生的鬼影现象，因此，本发明可以大幅降低折叠光路中因菲涅尔反 射产生的鬼影现象，从而提高显示光学系统的图像质量。而且，因为透镜和偏振分光元件之间的距离可以根据实际需求进行调整，以满足光学设计的屈光度和像质的要求，因而可以避免透镜较厚、重量上升等不利因素，故本降低鬼影的显示光学系统具有轻量化的特点，能够满足头戴显示装置对重量的要求，便于在产品中推广应用。
附图说明
为了更清楚地说明本申请实施例或现有技术中的技术方案，下面将对实施例或现有技术描述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申请的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图示出的结构获得其他的附图。
图1为基本的折叠光路的结构示意图(图中箭头所指方向为主像光路的方向)；
图2为本申请降低鬼影的显示光学系统一实施例的结构示意图(图中箭头所指方向为剩余的鬼影光路的方向)；
图3为本申请降低鬼影的显示光学系统另一实施例的结构示意图(图中箭头所指方向为剩余的鬼影光路的方向)；
图4为图3降低鬼影的显示光学系统中透镜与第二偏振转换元件贴合的结构示意图；
图5为图3降低鬼影的显示光学系统中透镜、第二偏振转换元件及基片贴合的结构示意图；
图6为本申请降低鬼影的显示光学系统又一实施例中透镜、第二偏振转换元件及基片贴合的结构示意图；
图7为基本的折叠光路的结构示意图(图中箭头所指方向为主像光路的方向)；
图8为本发明降低鬼影的显示光学系统一实施例的结构示意图(图中箭头所指方向为剩余的鬼影光路的方向)；
图9为本发明降低鬼影的显示光学系统另一实施例的结构示意图(图中箭头所指方向为剩余的鬼影光路的方向)；
图10为图9降低鬼影的显示光学系统中透镜与第一偏振转换元件贴合的结构示意图；
图11为图9降低鬼影的显示光学系统中透镜、第一偏振转换元件及基片贴合的结构示意图；
图12为本发明降低鬼影的显示光学系统又一实施例中透镜、第一偏振转换元件及基片贴合的结构示意图。
附图标号说明：
Figure PCTCN2021111747-appb-000001
本申请目的的实现、功能特点及优点将结合实施例，参照附图做进一步说明。
具体实施方式
下面将结合本申请实施例中的附图，对本申请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申请的一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其他 实施例，都属于本申请保护的范围。
需要说明，若本申请实施例中有涉及方向性指示(诸如上、下、左、右、前、后……)，则该方向性指示仅用于解释在某一特定姿态(如附图所示)下各部件之间的相对位置关系、运动情况等，如果该特定姿态发生改变时，则该方向性指示也相应地随之改变。
另外，若本申请实施例中有涉及“第一”、“第二”等的描述，则该“第一”、“第二”等的描述仅用于描述目的，而不能理解为指示或暗示其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至少一个该特征。另外，各个实施例之间的技术方案可以相互结合，但是必须是以本领域普通技术人员能够实现为基础，当技术方案的结合出现相互矛盾或无法实现时应当认为这种技术方案的结合不存在，也不在本申请要求的保护范围之内。
本申请提出一种降低鬼影的显示光学系统100。
作为本申请的一种实施方式，请参阅图2至5，该降低鬼影的显示光学系统，包括依序设置的显示屏10、偏振件20、第一偏振转换元件30、部分透射部分反射元件90、第二偏振转换元件50和偏振分光元件60；显示光学系统还包括设置于部分透射部分反射元件90背离显示屏的一侧的透镜40；透镜40与第二偏振转换元件50贴合设置，和/或，透镜40与偏振分光元件60贴合设置；第二偏振转换元件50与偏振分光元件60之间间隔设置，第二偏振转换元件50暴露于空气中的表面设置有基片70，且基片70上设置有增透膜71。
请参阅图1，图1示出的是基本的折叠光路的结构示意图(图中箭头所指方向为主像光路的方向)。基本的折叠光路结构，包括依序设置的偏振件20、第一偏振转换元件30、部分透射部分反射元件90、透镜40、第二偏振转换元件50和偏振分光元件60。
其中，偏振件20优选吸收型偏光片，比如显示行业常用的PVA(polyvinyl alcohol，聚乙烯醇)偏光片。第一偏振转换元件30具体来说是四分之一波片QWP(quarter wave plate)，该四分之一波片能够对入射偏振光在快慢轴分量间产生四分之一波长的延迟量，通常情况下，该四分之一波片光轴与偏光片透过轴的方位角为40°～50°，进一步为44°～46°。透镜40带有一定屈光度，可以为平凸透镜、双凸透镜或者焦距为正的弯月透镜，为了达到更好的像差控制，优选双凸形状的透镜40，即透镜40朝向第一偏振转换元件30的表面和透镜40朝向第二偏振转换元件50的表面均为凸面。部分透射部分反射元件90(比如分光膜，通常为透反膜)可以与透镜40分离设置，也可以贴合设置在透镜40朝向屏幕一侧的表面，优选贴合设置在透镜40朝向屏幕一侧的表面，透过率为30％～70％，进一步为40％～60％。第二偏振转换元件50具体来说是四分之一波片(QWP，quarter wave plate)，第二偏振转换元件50的材料可以与第一偏振转换元件30相同，也可以不同，优选与第一偏振转换元件30相同的材料。第二偏振转换元件50的光轴方向通常有两种，一种方案为平行于第一偏振转换元件30，另一种方案为垂直于第一偏振转换元件30。当采用第一种方案时，偏振分光元件60(PBS，polarization beam splitter)的透过轴与偏振件20平行，当采用第二种方案时，偏振分光元件60的透过轴与偏振件20垂直。通过这样配置，偏振分光元件60可以反射直透的偏振光，从而达到光路折叠的效果。偏振分光元件60，可以选择布拉格型反射偏振器件，也可以选择金属线栅型(wire grid)反射偏振器件。
在上述折叠光路结构中，光线的具体走向如下：显示屏10上像元的光经偏振件20起偏为线偏，通过第一偏振转换元件30后变为圆偏光，继续穿过第二偏振转换元件50后再次变为线偏光，此时偏振方向与偏振分光元件60的透过轴垂直，因而被反射，并第二次穿过第二偏振转换元件50，反射光到达部分透射部分反射元件90时被反射，同时由于反射带来的半波损失，圆偏光的手性发生翻转，导致该光线第三次穿过第二偏振转换元件50后的偏振态与第一次穿过第二偏振转换元件50后的偏振态正交，因此能够被偏振分光元件60透过，从而形成主像。
在上述基本的折叠光路的基础上，对本申请的降低鬼影的显示光学系统进行具体说 明，在本申请实施例中，透镜40设置于部分透射部分反射元件90背离显示屏的一侧；透镜40与第二偏振转换元件50贴合设置，和/或，透镜40与偏振分光元件60贴合设置；第二偏振转换元件50与偏振分光元件60之间间隔设置，第二偏振转换元件50暴露于空气中的表面设置有基片70，且基片70上设置有增透膜71。
具体地，上述结构至少包括四种情形：
第一种，透镜40设于部分透射部分反射元件90和第二偏振转换元件50之间，透镜40与第二偏振转换元件50贴合设置，第二偏振转换元件50朝向偏振分光元件60的表面设置有基片70和增透膜71。
第二种，透镜40设于第二偏振转换元件50和偏振分光元件60之间，透镜40与第二偏振转换元件50贴合设置，且透镜40与偏振分光元件60间隔设置，第二偏振转换元件50朝向第一偏振转换元件30的表面设置有基片70和增透膜71。
第三种，透镜40设于第二偏振转换元件50和偏振分光元件60之间，透镜40同时与第二偏振转换元件50和偏振分光元件60贴合设置，第二偏振转换元件50朝向第一偏振转换元件30的表面设置有基片70和增透膜71。
第四种，透镜40设于偏振分光元件60背离第二偏振转换元件50的一侧，透镜40与偏振分光元件60贴合设置；当第二偏振转换元件50与部分透射部分反射元件90贴合设置时，则第二偏振转换元件50朝向偏振分光元件60的表面设置有基片70和增透膜71；当第二偏振转换元件50与偏振分光元件60贴合设置时，则第二偏振转换元件50朝向第一偏振转换元件30的表面设置有基片70和增透膜71。
需要说明的是，而第二偏振转换元件50与偏振分光元件60之间间隔设置，可以是通过透镜40间隔，也是可以通过空气间隔。当透镜40与第二偏振转换元件50贴合设置，或透镜40与偏振分光元件60贴合设置时，第二偏振转换元件50与偏振分光元件60之间设置空气间隔。当透镜40同时与第二偏振转换元件50和偏振分光元件60贴合设置时，第二偏振转换元件50和偏振分光元件60之间通过透镜40间隔。
可以理解的是，透镜40与第二偏振转换元件50贴合设置，或，透镜40与偏振分光元件60贴合设置，或，透镜40同时与第二偏振转换元件50和偏振分光元件60贴合设置，即透镜40与相邻元件中的一个或两个直接接触，透镜40和与之贴合的相邻元件之间没有空气隔离，因此可以减少相应界面的菲涅尔反射带来的鬼影。同时，在第二偏振转换元件50暴露于空气中的表面设有基片70以及位于基片70上的增透膜71，增透膜71，又称减反射膜，它的主要功能是减少光学表面的反射光，增加透光率，因而可以在一个实施例中降低菲涅尔反射产生的鬼影现象。综上，透镜40与第二偏振转换元件50贴合设置，和/或，偏振分光元件60贴合设置，配合第二偏振转换元件50暴露于空气中的表面设置基片70和增透膜71，可以大幅降低菲涅尔反射产生的鬼影现象，从而提高显示光学系统的图像质量。
实际中，如果直接在第二偏振转换元件50朝向偏振分光元件60的表面镀增透(AR)膜，表面反射通常在0.5～1％之间，并且色散性能较差，容易产生明显的偏色现象，同时无法得到较高的可靠性。本实施例中，在第二偏振转换元件50朝向偏振分光元件60的表面增设一个基片70，然后再在基片70朝向偏振分光元件60的表面镀增透(AR)膜，则表面反射率可以显著降低，比如0.3％，并且具有更高的可靠性。因此，相较于直接在第二偏振转换元件50的表面镀增透膜71，本实施例中，鬼影可以进一步下降50％～70％，降低鬼影的效果更为明显。
需要说明的是，本申请对显示屏10、偏振件20、第一偏振转换元件30、部分透射部分反射元件90、透镜40、偏振分光元件60中任意两个元件之间的距离并不进行限制，可以根据实际需要进行设置。比如，透镜40和偏振分光元件60的间距可以根据主像的光学设计来确定。因此，本技术方案能够满足光学设计的屈光度调节和成像像质的要求，避免了透镜40较厚、重量上升等不利因素，适于在产品中推广应用。故本降低鬼影的显示光 学系统100还具有轻量化的特点，可满足头戴显示(HMD)装置对重量的要求。
在一实施例中，作为本发明的一种实施方式，请参阅图8至11，该降低鬼影的显示光学系统，包括依序设置的显示屏10、偏振分光元件60、第一偏振转换元件30、部分透射部分反射元件90、第二偏振转换元件50和偏振件20；显示光学系统还包括设置于部分透射部分反射元件90朝向显示屏的一侧的透镜40；透镜40与第一偏振转换元件30贴合设置，和/或，透镜40与偏振分光元件60贴合设置；第一偏振转换元件30与偏振分光元件60之间间隔设置，第一偏振转换元件30暴露于空气中的表面设置有基片70，且基片70上设置有增透膜71。
请参阅图7，图7示出的是基本的折叠光路的结构示意图(图中箭头所指方向为主像光路的方向)。基本的折叠光路结构，包括依序设置的显示屏10、偏振分光元件60、第一偏振转换元件30、透镜40、部分透射部分反射元件90、第二偏振转换元件50和偏振件20。
其中，偏振分光元件60(PBS，polarization beam splitter)，可以选择布拉格型反射偏振器件，也可以选择金属线栅型(wire grid)反射偏振器件。第一偏振转换元件30具体来说是四分之一波片(QWP，quarter wave plate)，该四分之一波片能够对入射偏振光在快慢轴分量间产生四分之一波长的延迟量，通常情况下，该四分之一波片光轴与偏振分光元件60透过轴的方位角为40°～50°，进一步为44°～46°。透镜40带有一定屈光度，可以为平凸透镜、双凸透镜或者焦距为正的弯月透镜，为了达到更好的像差控制，优选双凸形状的透镜40，即透镜40朝向第一偏振转换元件30的表面和透镜40朝向第二偏振转换元件50的表面均为凸面。部分透射部分反射元件90(比如分光膜，通常为透反膜)可以与透镜40分离设置，也可以贴合设置在透镜40背离屏幕一侧的表面，优选贴合设置在透镜背离屏幕一侧的表面，透过率为30％～70％，进一步为40％～60％。第二偏振转换元件50具体来说是四分之一波片(QWP，quarter wave plate)，第二偏振转换元件50的材料可以与第一偏振转换元件30相同，也可以不同，优选与第一偏振转换元件30相同的材料。第二偏振转换元件50的光轴方向通常有两种，一种方案为平行于第一偏振转换元件30，另一种方案为垂直于第一偏振转换元件30。当采用第一种方案时，偏振件20的透过轴与偏振分光元件60平行，当采用第二种方案时，偏振件20的透过轴与偏振分光元件60垂直。偏振件20优选吸收型偏光片，比如显示行业常用的PVA(polyvinyl alcohol，聚乙烯醇)偏光片。通过这样配置，偏振件20可以吸收直透光路的偏振光，而透过折叠光路的偏振光，从而达到正确显示光路折叠主像的效果。
在上述折叠光路结构中，光线的具体走向如下：显示屏10上像元的光经偏振分光元件60起偏为线偏，通过第一偏振转换元件30后变为圆偏光，到达部分透射部分反射元件90时被反射，并第二次穿过第一偏振转换元件30，由于反射带来的半波损失，圆偏光的手性发生翻转，反射光到达偏振分光元件60时，其偏振方向平行于偏振分光元件60的反射轴而被反射，当光线第三次经过第一偏振元件30时，其手性与第一次经过时相反，继续穿过第二偏振转换元件50后再次变为线偏光，此时偏振方向与偏振件20的透过轴平行，因而能够透过形成主像。
在上述基本的折叠光路的基础上，对本发明的降低鬼影的显示光学系统进行具体说明，在本发明实施例中，透镜40设置于部分透射部分反射元件90朝向显示屏的一侧；透镜40与第一偏振转换元件30贴合设置，和/或，透镜40与偏振分光元件60贴合设置；第一偏振转换元件30与偏振分光元件60之间间隔设置，第一偏振转换元件30暴露于空气中的表面设置有基片70，且基片70上设置有增透膜71。
具体地，上述结构至少包括四种情形：
第一种，透镜40设于部分透射部分反射元件90和第一偏振转换元件30之间，透镜40与第二偏振转换元件50贴合设置，第一偏振转换元件30朝向偏振分光元件60的表面设置有基片70和增透膜71。
第二种，透镜40设于第一偏振转换元件30和偏振分光元件60之间，透镜40与第一偏振转换元件30贴合设置，且透镜40与偏振分光元件60间隔设置，第一偏振转换元件30朝向第一偏振转换元件30的表面设置有基片70和增透膜71。
第三种，透镜40设于第一偏振转换元件30和偏振分光元件60之间，透镜40同时与第一偏振转换元件30和偏振分光元件60贴合设置，第一偏振转换元件30朝向第一偏振转换元件30的表面设置有基片70和增透膜71。
第四种，透镜40设于偏振分光元件60背离第一偏振转换元件30的一侧，透镜40与偏振分光元件60贴合设置；当第一偏振转换元件30与部分透射部分反射元件90贴合设置时，则第一偏振转换元件30朝向偏振分光元件60的表面设置有基片70和增透膜71；当第一偏振转换元件30与偏振分光元件60贴合设置时，则第一偏振转换元件30朝向第一偏振转换元件30的表面设置有基片70和增透膜71。
需要说明的是，而第一偏振转换元件30与偏振分光元件60之间间隔设置，可以是通过透镜40间隔，也是可以通过空气间隔。当透镜40与第一偏振转换元件30贴合设置，或透镜40与偏振分光元件60贴合设置时，第一偏振转换元件30与偏振分光元件60之间设置空气间隔。当透镜40同时与第一偏振转换元件30和偏振分光元件60贴合设置时，第一偏振转换元件30和偏振分光元件60之间通过透镜40间隔。
可以理解的是，透镜40与第一偏振转换元件30贴合设置，或，透镜40与偏振分光元件60贴合设置，或，透镜40同时与第一偏振转换元件30和偏振分光元件60贴合设置，即透镜40与相邻元件中的一个或两个直接接触，透镜40和与之贴合的相邻元件之间没有空气隔离，因此可以减少相应界面的菲涅尔反射带来的鬼影。同时，在第一偏振转换元件30暴露于空气中的表面设有基片70以及位于基片70上的增透膜71，增透膜71，又称减反射膜，它的主要功能是减少光学表面的反射光，增加透光率，因而可以进一步地降低菲涅尔反射产生的鬼影现象。综上，透镜40与第一偏振转换元件30贴合设置，和/或，偏振分光元件60贴合设置，配合第一偏振转换元件30暴露于空气中的表面设置基片70和增透膜71，可以大幅降低菲涅尔反射产生的鬼影现象，从而提高显示光学系统的图像质量。
实际中，如果直接在第一偏振转换元件30朝向偏振分光元件60的表面镀增透(AR)膜，表面反射通常在0.5～1％之间，并且色散性能较差，容易产生明显的偏色现象，同时无法得到较高的可靠性。本实施例中，在第一偏振转换元件30朝向偏振分光元件60的表面增设一个基片70，然后再在基片70朝向偏振分光元件60的表面镀增透(AR)膜，则表面反射率可以显著降低，比如0.3％，并且具有更高的可靠性。因此，相较于直接在第一偏振转换元件30的表面镀增透膜71，本实施例中，鬼影可以进一步下降50％～70％，降低鬼影的效果更为明显。
需要说明的是，本发明对显示屏10、偏振分光元件60、第一偏振转换元件30、部分透射部分反射元件90、透镜40、偏振件20中任意两个元件之间的距离并不进行限制，可以根据实际需要进行设置。比如，透镜40和偏振分光元件60的间距可以根据主像的光学设计来确定。因此，本技术方案能够满足光学设计的屈光度调节和成像像质的要求，避免了透镜40较厚、重量上升等不利因素，适于在产品中推广应用。故本降低鬼影的显示光学系统100还具有轻量化的特点，可满足头戴显示(HMD)装置对重量的要求。
在本申请的一实施例中，请参照图3至5，透镜40设置于部分透射部分反射元件90与第二偏振转换元件50之间，透镜40同时与部分透射部分反射元件90和第二偏振转换元件50贴合设置，第二偏振转换元件50与偏振分光元件60之间存在空气间隔，第二偏振转换元件50朝向偏振分光元件60的表面、偏振分光元件60朝向第二偏振转换元件50的表面上均设置有基片70和增透膜71。
其中，由基片70的后表面(即朝向偏振分光元件60)的界面反射形成的剩余的鬼影 光路如图2中所示，其相对主像的比例为RR pcos 2δ，其中R为部分透射部分反射元件90的反射率，Rp为偏振分光元件60在透过轴方向的反射率，cosδ是由第二偏振转换元件50的延迟量偏离四分之一光程造成的漏光。
本实施例中，透镜40与部分透射部分反射元件90直接接触，且透镜40与第二偏振转换元件50直接接触，则透镜40与部分透射部分反射元件90之间，以及透镜40与第二偏振转换元件50之间均没有空气隔离，可以减少相应界面的菲涅尔反射带来的鬼影；同时，第二偏振转换元件50暴露在空气中的表面(即朝向偏振分光元件60的表面)和偏振分光元件60暴露在空气中的表面(即朝向第二偏振转换元件50的表面)均设有基片70和增透膜71，基片70可以使表面反射率显著降低，并且使增透膜71具有更高的可靠性，增透膜71可以在一个实施例中降低菲涅尔反射产生的鬼影现象，从而提高显示光学系统的图像质量。此外，透镜40和偏振分光元件60的间距可以根据主像的光学设计来确定，以满足光学设计的屈光度调节和成像像质的要求。
在本发明的一实施例中，请参照图9至11，透镜40设置于部分透射部分反射元件90与第一偏振转换元件30之间，透镜40同时与部分透射部分反射元件90和第一偏振转换元件30贴合设置，第一偏振转换元件30与偏振分光元件60之间存在空气间隔，第一偏振转换元件30朝向偏振分光元件60的表面、偏振分光元件60朝向第一偏振转换元件30的表面上均设置有基片70和增透膜71。
其中，由基片70的前表面(即朝向偏振分光元件60)的界面反射形成的剩余的鬼影光路如图8中所示，其相对主像的比例为RR pcos 2δ，其中R为部分透射部分反射元件90的反射率，Rp为偏振分光元件60在透过轴方向的反射率，cosδ是由第一偏振转换元件30的延迟量偏离四分之一光程造成的漏光。
本实施例中，透镜40与部分透射部分反射元件90直接接触，且透镜40与第一偏振转换元件30直接接触，则透镜40与部分透射部分反射元件90之间，以及透镜40与第一偏振转换元件30之间均没有空气隔离，可以减少相应界面的菲涅尔反射带来的鬼影。同时，第一偏振转换元件30暴露在空气中的表面(即朝向偏振分光元件60的表面)和偏振分光元件60暴露在空气中的表面(即朝向第一偏振转换元件30的表面)均设有基片70和增透膜71，基片70可以使表面反射率显著降低，并且使增透膜71具有更高的可靠性，增透膜71可以进一步地降低菲涅尔反射产生的鬼影现象，从而提高显示光学系统的图像质量。此外，透镜40和偏振分光元件60的间距可以根据主像的光学设计来确定，以满足光学设计的屈光度调节和成像像质的要求。
在一个实施例中，请参照图4至5，基片70朝向第二偏振转换元件50的表面的曲率和基片70朝向偏振分光元件60的表面的曲率相同。
本实施例中，基片70无光焦度，即基片70的前后表面的曲率相同，故不会影响原有光路结构中光线的走向，从而能够保证原有光路结构的正常工作，保证原有光路结构的光学性能。
在一个实施例中，请参照图10至11，基片70朝向第一偏振转换元件30的表面的曲率和基片70朝向偏振分光元件60的表面的曲率相同。
本实施例中，基片70无光焦度，即基片70的前后表面的曲率相同，故不会影响原有光路结构中光线的走向，从而能够保证原有光路结构的正常工作，保证原有光路结构的光学性能。
在一个实施例中，请参照图4至5，基片70朝向第二偏振转换元件50的表面的曲率与透镜40朝向第二偏振转换元件50的表面的曲率相同。
具体地，第二偏振转换元件50(比如为四分之一波片)可以由晶体、聚合物拉伸、液 晶涂布等方式构成，优选聚合物拉伸与液晶涂布等薄膜形态，以方便与不同曲率半径的透镜的曲面贴合。当第二偏振转换元件50与透镜40的表面贴合时，第二偏振转换元件50能够适应透镜40的形状。并且，本实施例中，基片70的前后表面的曲率还与透镜40的后表面(即朝向第二偏振转换元件50的表面)的曲率相同，因此，基片70可以与透镜40后表面上的第二偏振转换元件50很好地胶合在一起，并且不会影响原有光路结构中光线的走向，从而保证成像质量。
在一实施例中，请参照图10至11，基片70朝向第一偏振转换元件30的表面的曲率与透镜40朝向第一偏振转换元件30的表面的曲率相同。
具体地，第一偏振转换元件30(比如为四分之一波片)可以由晶体、聚合物拉伸、液晶涂布等方式构成，优选聚合物拉伸与液晶涂布等薄膜形态，以方便与不同曲率半径的透镜的曲面贴合。当第一偏振转换元件30与透镜40的表面贴合时，第一偏振转换元件30能够适应透镜40的形状。并且，本实施例中，基片70的前后表面的曲率还与透镜40的后表面(即朝向第一偏振转换元件30的表面)的曲率相同，因此，基片70可以与透镜40后表面上的第一偏振转换元件30很好地胶合在一起，并且不会影响原有光路结构中光线的走向，从而保证成像质量。
在本申请的又一实施例中，请参照图6，基片70朝向第二偏振转换元件50的表面为平面。
在透镜40的后表面(即朝向第二偏振转换元件50的表面)的面型接近平面的情况下，例如R>400mm，基片70可以考虑选用平面元件，即基片70的前后表面(即朝向第二偏振转换元件50和朝向偏振分光元件60的表面)均为平面，当直径达到40mm时，边缘间隙小于0.5mm，便于光学胶的填充和固化，光学胶优选折射率匹配材质，填充后的组合透镜相当于由折射率匹配材质形成的透镜与透镜40胶合。如此，同样可以实现降低鬼影的效果，这种结构可以降低工艺难度和制作成本，但胶合透镜带来的影响需要在成像设计时予以考虑。
在本发明的又一实施例中，请参照图12，基片70朝向第一偏振转换元件30的表面为平面。
在透镜40的前表面(即朝向第一偏振转换元件30的表面)的面型接近平面的情况下，例如R>500mm，基片70可以考虑选用平面元件，即基片70的前后表面(即朝向第一偏振转换元件30和朝向偏振分光元件60的表面)均为平面，当直径达到40mm时，边缘间隙小于0.5mm，便于光学胶的填充和固化，光学胶优选折射率匹配材质，填充后的组合透镜相当于由折射率匹配材质形成的透镜与透镜40胶合。如此，同样可以实现降低鬼影的效果，这种结构可以降低工艺难度和制作成本，但胶合透镜带来的影响需要在成像设计时予以考虑。
在一个实施例中，基片70具有与透镜40相反的色散特性。
基片70通过选用合适的材料，可以在不影响已有光学性能的前提下对系统的色差进行额外校正。具体来说，平板型或者不带屈光度(即前后表面的曲率相同)的基片70，其位置色差为正色差，与折射率、厚度和阿贝数有关，而凸透镜40具有负的位置色差，因此可以基于相应的色差计算公式，如初级赛德尔像差以及高级色差来选择合适的材料和厚度，使得显示光学系统具有更理想的色差表现。本实施例中，通过具有与透镜40相反的色散特性的基片70对透镜40的色差进行补偿，可以有效消除色差。
在一个实施例中，透镜40和第二偏振转换元件50之间填充有光学胶80。
本实施例中，透镜40与第二偏振转化元件之间通过光学胶80胶合在一起。光学胶80(光学零件胶合用胶)是用于胶结透明光学零件的特种胶粘剂，要求具有无色透明、光透过率在90％以上、胶结强度良好，可在室温或中温下固化，且有固化收缩小等特点。有机硅胶、丙烯酸型树脂及不饱和聚酯、聚氨酯、环氧树脂等胶粘剂都可胶结光学零件。光学 胶80是一种与光学零件的光学性能相近，并具有优良胶接性能的高分子物质。光学胶80可以选择涂覆在透镜40的后表面(即朝向第二偏振转换元件50的表面)上，也可以选择涂覆在第二偏振转换元件50的前表面(即朝向透镜40的表面)上，优选涂覆在第二偏振转换元件50上，因为第二偏振转换元件50(比如四分之一波片)整体呈软质，在第二偏振转换元件50贴合到透镜40前，第二偏振转换元件50可以处于平面状态，在第二偏振转换元件50的前表面涂覆光学胶80后，再将第二偏振转换元件50贴合到透镜40的后表面并适应透镜40的凸面形状，能够实现更好的均匀度和平整度。同时，需要用除泡机进行真空除泡操作，以避免第二偏振转换元件50和透镜40胶合时，二者间隙的气泡残留对成像光线造成散射。
在一个实施例中，透镜40和第一偏振转换元件30之间填充有光学胶80。
本实施例中，透镜40与第二偏振转化元件之间通过光学胶80胶合在一起。光学胶80(光学零件胶合用胶)是用于胶结透明光学零件的特种胶粘剂，要求具有无色透明、光透过率在90％以上、胶结强度良好，可在室温或中温下固化，且有固化收缩小等特点。有机硅胶、丙烯酸型树脂及不饱和聚酯、聚氨酯、环氧树脂等胶粘剂都可胶结光学零件。光学胶80是一种与光学零件的光学性能相近，并具有优良胶接性能的高分子物质。光学胶80可以选择涂覆在透镜40的后表面(即朝向第一偏振转换元件30的表面)上，也可以选择涂覆在第一偏振转换元件30的前表面(即朝向透镜40的表面)上，优选涂覆在第一偏振转换元件30上，因为第一偏振转换元件30(比如四分之一波片)整体呈软质，在第一偏振转换元件30贴合到透镜40前，第一偏振转换元件30可以处于平面状态，在第一偏振转换元件30的前表面涂覆光学胶80后，再将第一偏振转换元件30贴合到透镜40的后表面并适应透镜40的凸面形状，能够实现更好的均匀度和平整度。同时，需要用除泡机进行真空除泡操作，以避免第一偏振转换元件30和透镜40胶合时，二者间隙的气泡残留对成像光线造成散射。
在一个实施例中，第二偏振转换元件50和基片70之间填充有光学胶80。
本实施例中，第二偏振转换元件50和基片70之间同样通过光学胶80胶合在一起。光学胶80可以选择涂覆在基片70的前表面(即朝向第二偏振转换元件50的表面)上，也可以选择涂覆在第二偏振转换元件50的后表面(即朝向偏振分光元件60的表面)上，优选涂覆在第二偏振转换元件50的后表面上，因为第二偏振转换元件50(比如四分之一波片)整体呈软质，在第二偏振转换元件50贴合到透镜40前，第二偏振转换元件50可以处于平面状态，在第二偏振转换元件50的前后表面涂覆光学胶80后，再将第二偏振转换元件50贴合到透镜40的后表面并适应透镜40的凸面形状，最后将基片70贴合在第二偏振转换元件50的后表面，能够实现更好的均匀度和平整度。同时，需要用除泡机进行真空除泡操作，以避免第二偏振转换元件50和基片70胶合时，二者间隙的气泡残留对成像光线造成散射。
在一个实施例中，第一偏振转换元件30和基片70之间填充有光学胶80。
本实施例中，第一偏振转换元件30和基片70之间同样通过光学胶80胶合在一起。光学胶80可以选择涂覆在基片70的前表面(即朝向第一偏振转换元件30的表面)上，也可以选择涂覆在第一偏振转换元件30的后表面(即朝向偏振分光元件60的表面)上，优选涂覆在第一偏振转换元件30的后表面上，因为第一偏振转换元件30(比如四分之一波片)整体呈软质，在第一偏振转换元件30贴合到透镜40前，第一偏振转换元件30可以处于平面状态，在第一偏振转换元件30的前后表面涂覆光学胶80后，再将第一偏振转换元件30贴合到透镜40的后表面并适应透镜40的凸面形状，最后将基片70贴合在第一偏振转换元件30的后表面，能够实现更好的均匀度和平整度。同时，需要用除泡机进行真空除泡操作，以避免第一偏振转换元件30和基片70胶合时，二者间隙的气泡残留对成像光线造成散射。
具体地，光学胶80采用折射率匹配材料。
此处匹配的意思就是减少界面两边物质的折射率差值，从而将反射光损失减少到最小。折射率匹配是光学的重要手段，其目的使得相接触物质的折射率符合一定规律，以减少光的反射或增大光的透射。通过选用折射率匹配材料能够减少光学系统内部的界面反射，从而降低鬼影，提高成像质量。
在一个实施例中，基片70的材质为玻璃、树脂或光学薄膜。
本实施例中，基片70的材料优选玻璃。由镀膜工艺可知，高温通常能够实现更好的镀膜效果，这是因为在对基底进行预处理时，首先起到活化的作用，增加了基底与膜料的化学键力，提高膜层与基底的结合力，同时降低基底杂气和高折射率膜料的吸收，另外，一些用作增透膜71的低折射材料如氟化镁(MgF2)只适合高温沉积，而玻璃通常有更好的耐高温特性，因此，与树脂和光学薄膜相比，基片70选用玻璃材质，能够实现更低的界面反射和更好的膜材可靠性。
本申请还提出一种降低鬼影的头戴显示装置，该降低鬼影的头戴显示装置包括头戴主体和降低鬼影的显示光学系统100，降低鬼影的显示光学系统100设于头戴主体内，该降低鬼影的显示光学系统100的具体结构参照上述实施例，由于本降低鬼影的头戴显示装置采用了上述所有实施例的全部技术方案，因此至少具有上述实施例的技术方案所带来的所有有益效果，在此不再一一赘述。
其中，头戴主体可以包括适于佩戴在用户头部的框架、用于调节框架束缚程度的松紧调节装置，以及与显示光学系统连接以对显示屏10进行控制的控制系统等，头戴主体的具体结构和设置可以采用现有技术，此处不再赘述。
以上所述仅为本申请的优选实施例，并非因此限制本申请的专利范围，凡是在本申请的申请构思下，利用本申请说明书及附图内容所作的等效结构变换，或直接/间接运用在其他相关的技术领域均包括在本申请的专利保护范围内。

Claims (20)

  1. 一种降低鬼影的显示光学系统，其中，包括依序设置的显示屏、偏振件、第一偏振转换元件、部分透射部分反射元件、第二偏振转换元件和偏振分光元件；
    所述显示光学系统还包设置于所述部分透射部分反射元件远离所述显示屏一侧的透镜；所述透镜与所述第二偏振转换元件贴合设置，和/或，所述透镜与所述偏振分光元件贴合设置；所述第二偏振转换元件与所述偏振分光元件之间间隔设置，所述第二偏振转换元件暴露于空气中的表面设置有基片，且所述基片上设置有增透膜。
  2. 如权利要求1所述的降低鬼影的显示光学系统，其中，所述透镜设置于所述部分透射部分反射元件与所述第二偏振转换元件之间，所述透镜同时与所述部分透射部分反射元件和所述第二偏振转换元件贴合设置，所述第二偏振转换元件与所述偏振分光元件之间存在空气间隔，所述第二偏振转换元件朝向所述偏振分光元件的表面、所述偏振分光元件朝向所述第二偏振转换元件的表面上均设置有所述基片和所述增透膜。
  3. 如权利要求2所述的降低鬼影的显示光学系统，所述基片朝向所述第二偏振转换元件的表面的曲率和所述基片朝向所述偏振分光元件的表面的曲率相同。
  4. 如权利要求3所述的降低鬼影的显示光学系统，其中，所述基片朝向所述第二偏振转换元件的表面的曲率与所述透镜朝向所述第二偏振转换元件的表面的曲率相同。
  5. 如权利要求3所述的降低鬼影的显示光学系统，其中，所述基片朝向所述第二偏振转换元件的表面为平面。
  6. 如权利要求3所述的降低鬼影的显示光学系统，其中，所述基片具有与所述透镜相反的色散特性。
  7. 如权利要求2至6中任一项所述的降低鬼影的显示光学系统，其中，所述透镜和所述第二偏振转换元件之间填充有光学胶。
  8. 如权利要求2至6中任一项所述的降低鬼影的显示光学系统，其中，所述第二偏振转换元件和所述基片之间填充有光学胶。
  9. 如权利要求7或8所述的降低鬼影的显示光学系统，其中，所述光学胶采用折射率匹配材料。
  10. 一种降低鬼影的头戴显示装置，其中，包括：
    头戴主体；及
    如权利要求1至9中任一项所述的降低鬼影的显示光学系统，所述降低鬼影的显示光学系统设于所述头戴主体内。
  11. 一种降低鬼影的显示光学系统，其中，包括依序设置的显示屏、偏振分光元件、第一偏振转换元件、部分透射部分反射元件、第二偏振转换元件和偏振件；
    所述显示光学系统还包括设置于所述部分透射部分反射元件朝向所述显示屏的一侧的透镜；所述透镜与所述第一偏振转换元件贴合设置，和/或，所述透镜与所述偏振分光元件贴合设置；所述第一偏振转换元件与所述偏振分光元件之间间隔设置，所述第一偏振转换元件暴露于空气中的表面设置有基片，且所述基片上设置有增透膜。
  12. 如权利要求11所述的降低鬼影的显示光学系统，其中，所述透镜设置于所述部分透射部分反射元件与所述第一偏振转换元件之间，所述透镜同时与所述部分透射部分反射元件和所述第一偏振转换元件与贴合设置，所述第一偏振转换元件与所述偏振分光元件之间存在空气间隔，所述第一偏振转换元件朝向所述偏振分光元件的表面、所述偏振分光元件朝向所述第一偏振转换元件的表面上均设置有所述基片和所述增透膜。
  13. 所述降低鬼影的显示光学系统还包括：所述基片朝向所述第一偏振转换元件的表面的曲率和所述基片朝向所述偏振分光元件的表面的曲率相同。
  14. 如权利要求13所述的降低鬼影的显示光学系统，其中，所述基片朝向所述第一 偏振转换元件的表面的曲率与所述透镜朝向所述第一偏振转换元件的表面的曲率相同。
  15. 如权利要求13所述的降低鬼影的显示光学系统，其中，所述基片朝向所述第一偏振转换元件的表面为平面。
  16. 如权利要求13所述的降低鬼影的显示光学系统，其中，所述基片具有与所述透镜相反的色散特性。
  17. 如权利要求12至16中任一项所述的降低鬼影的显示光学系统，其中，所述透镜和所述第一偏振转换元件之间填充有光学胶。
  18. 如权利要求12至16中任一项所述的降低鬼影的显示光学系统，其中，所述第一偏振转换元件和所述基片之间填充有光学胶。
  19. 如权利要求17或18所述的降低鬼影的显示光学系统，其中，所述光学胶采用折射率匹配材料。
  20. 一种降低鬼影的头戴显示装置，其中，包括：
    头戴主体；及
    如权利要求11至19中任一项所述的降低鬼影的显示光学系统，所述降低鬼影的显示光学系统设于所述头戴主体内。
PCT/CN2021/111747 2020-10-26 2021-08-10 降低鬼影的显示光学系统及头戴显示装置 WO2022088836A1 (zh)

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