CN112305763A - Display optical system for reducing ghost and head-mounted display device - Google Patents
Display optical system for reducing ghost and head-mounted display device Download PDFInfo
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- CN112305763A CN112305763A CN202011161123.5A CN202011161123A CN112305763A CN 112305763 A CN112305763 A CN 112305763A CN 202011161123 A CN202011161123 A CN 202011161123A CN 112305763 A CN112305763 A CN 112305763A
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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
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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
Abstract
The invention discloses a display optical system and a head-mounted display device for reducing ghost, wherein the display optical system for reducing ghost comprises a display screen, a polarization piece, a first polarization conversion element, a partial transmission partial reflection element, a second polarization conversion element and a polarization beam splitting element which are sequentially arranged; the display optical system further comprises a lens disposed on a side of the partially transmissive partially reflective element facing away from the display screen; the lens is attached to the second polarization conversion element, and/or the lens is attached to the polarization beam splitting element; the second polarization conversion element and the polarization light splitting element are arranged at intervals, the surface of the second polarization conversion element exposed in the air is provided with a substrate, and the substrate is provided with an antireflection film. The technical scheme of the invention can reduce the ghost image caused by Fresnel reflection generated by exposing the interfaces of different elements in the folded optical path in the air so as to improve the image quality of the display optical system and has the characteristic of light weight.
Description
Technical Field
The present invention relates to the field of optical display technologies, and in particular, to a display optical system and a head-mounted display device for reducing ghosting.
Background
In near eye display (ned) or head mounted display (hmd) optical systems, optical films (optical films) are becoming more and more widely used because of their functionality and cost performance, such as polarization control elements, polarizers, compensators, etc., playing an important role in folded optical paths (pancakes). However, exposure of these elements to air can cause fresnel reflection (a phenomenon in which a portion of light is reflected when the light is incident on an interface between two media having different refractive indices), which in turn causes ghost images that affect image quality.
There are three main approaches to solve this problem. The first is to coat an AR (Anti-Reflection) layer on the surface of the polarization control element or to combine an optical film with AR function, but these materials can only have low reflectivity around 589nm (for example<0.7%, DNP LR Film) does not achieve good uniformity over the entire visible range. The second is a quarter-wave plate QWP (Quarter waveplate) Compounded with a polarizing beam splitter pbs (polarizing beam splitter) and then attached to a substrate, this approach reduces one optical reflection surface, but the reflection from the remaining optical surface is still significant and the corresponding ghosting dominates the imaging. The third is to combine the QWP and the PBS, and attach the QWP to the rear surface of the lens, or attach the QWP to the two lenses, so as to reduce the corresponding reflection, but in order to meet the requirements of diopter and image quality, the solution has disadvantages of thicker lens, increased weight, and the like, and thus the application of the QWP in the product is limited.
Disclosure of Invention
The invention mainly aims to provide a display optical system for reducing ghosting, aiming at reducing ghosting caused by Fresnel reflection generated by exposing interfaces of different elements in a folded optical path in air, improving the image quality of the display optical system and having the characteristic of light weight.
In order to achieve the above object, the present invention provides a display optical system for reducing ghost, which includes a display screen, a polarizer, a first polarization conversion element, a partially transmissive and partially reflective element, a second polarization conversion element, and a polarization splitting element, which are sequentially disposed; the display optical system further comprises a lens disposed on a side of the partially transmissive partially reflective element facing away from the display screen; the lens is attached to the second polarization conversion element, and/or the lens is attached to the polarization beam splitting element; the second polarization conversion element and the polarization light splitting element are arranged at intervals, the surface of the second polarization conversion element exposed in the air is provided with a substrate, and the substrate is provided with an antireflection film.
Optionally, the lens is disposed between the partially transmissive partially reflective element and the second polarization conversion element, the lens is simultaneously attached to the partially transmissive partially reflective element and the second polarization conversion element, an air space exists between the second polarization conversion element and the polarization splitting element, and a substrate and an antireflection film are disposed on a surface of the second polarization conversion element facing the polarization splitting element and a surface of the polarization splitting element facing the second polarization conversion element.
Alternatively, the curvature of the surface of the substrate facing the second polarization conversion element and the curvature of the surface of the substrate facing the polarization splitting element are the same.
Alternatively, the curvature of the surface of the substrate facing the second polarization conversion element is the same as the curvature of the surface of the lens facing the second polarization conversion element.
Optionally, a surface of the substrate facing the second polarization conversion element is planar.
Optionally, the substrate has a dispersion characteristic opposite to that of the lens.
Optionally, an optical glue is filled between the lens and the second polarization conversion element.
Optionally, an optical adhesive is filled between the second polarization conversion element and the substrate.
Optionally, the optical cement is made of an index matching material.
To achieve the above object, the present invention further provides a head-mounted display device for reducing ghosting, including: a head-mounted body; and the display optical system for reducing the ghost is arranged in the head-mounted main body.
According to the technical scheme, the display screen, the polarization piece, the first polarization conversion element, the partial transmission partial reflection element, the second polarization conversion element and the polarization light splitting element are sequentially arranged, and the lens is arranged on one side, away from the display screen, of the partial transmission partial reflection element, so that diopter superposition of a folding light path can be achieved. 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 directly contacted with one or two adjacent elements, namely, no air isolation exists between the lens and the adjacent elements attached to the lens, and therefore ghost images caused by Fresnel reflection of corresponding interfaces can be reduced; meanwhile, the substrate and the antireflection film positioned on the substrate are arranged on the surface of the second polarization conversion element exposed in the air, so that the substrate can obviously reduce the surface reflectivity, the antireflection film has higher reliability, and the antireflection film can further reduce the ghost phenomenon generated by Fresnel reflection. Moreover, because the distance between the lens and the polarization beam splitting element can be adjusted according to actual requirements to meet the requirements of diopter and image quality of optical design, adverse factors such as thicker lens and increased weight can be avoided, so that the display optical system for reducing ghost has the characteristic of light weight, can meet the requirements of a head-mounted display device on weight, and is convenient to popularize and apply in products.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.
FIG. 1 is a schematic 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 diagram of a display optical system for reducing ghosting according to an embodiment of the present invention (the direction indicated by the arrow in the figure is the direction of the remaining ghost optical path);
FIG. 3 is a schematic structural diagram of another embodiment of a display optical system for reducing ghosting according to the present invention (the direction indicated by the arrow in the figure is the direction of the remaining ghost optical path);
FIG. 4 is a schematic view of the display optical system for reducing ghost in FIG. 3 with a lens attached to a second polarization conversion element;
FIG. 5 is a schematic view of the lens, the second polarization conversion element and the substrate of the display optical system for reducing ghost in FIG. 3;
FIG. 6 is a schematic view of a lens, a second polarization conversion element and a substrate in another embodiment of the display optical system for reducing ghosting.
The reference numbers illustrate:
the implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that, if directional indications (such as up, down, left, right, front, and back … …) are involved in the embodiment of the present invention, the directional indications are only used to explain the relative positional relationship between the components, the movement situation, and the like in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indications are changed accordingly.
In addition, if there is a description of "first", "second", etc. in an embodiment of the present invention, the description of "first", "second", etc. is for descriptive purposes only and is not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention.
The present invention provides a display optical system 100 for reducing ghost image.
As an embodiment of the present invention, referring to fig. 2 to 5, the display optical system for reducing ghost includes a display screen 10, a polarizer 20, a first polarization conversion element 30, a partially transmissive and partially reflective element 90, a second polarization conversion element 50, and a polarization splitting element 60, which are sequentially disposed; the display optical system further comprises a lens 40 arranged at a side of the partially transmissive partially reflective element 90 facing away from the display screen; the lens 40 is attached to the second polarization conversion element 50, and/or the lens 40 is attached to the polarization beam splitting element 60; the second polarization conversion element 50 and the polarization beam splitting element 60 are arranged at intervals, a substrate 70 is arranged on the surface of the second polarization conversion element 50 exposed to the air, and an antireflection film 71 is arranged on the substrate 70.
Referring to fig. 1, fig. 1 is a schematic diagram illustrating a basic structure of a folded optical path (the direction indicated by an arrow in the figure is the direction of a main image optical path). The basic folded optical path structure includes a polarizing member 20, a first polarization conversion element 30, a partially transmissive partially reflective element 90, a lens 40, a second polarization conversion element 50, and a polarization splitting element 60, which are sequentially disposed.
Among them, the polarizer 20 is preferably an absorption type polarizer such as a PVA (polyvinyl alcohol) polarizer commonly used in the display industry. The first polarization conversion element 30 is specifically a quarter-wave plate qwp (quarter wave plate) capable of generating a retardation of a quarter wavelength between fast and slow axis components for the incident polarized light, and an azimuth angle of an optical axis of the quarter-wave plate to a transmission axis of the polarizer is usually 40 ° to 50 °, and further 44 ° to 46 °. The lens 40 has a certain refractive power and may be a plano-convex lens, a biconvex lens or a meniscus lens with a positive focal length, and for better aberration control, the lens 40 is preferably biconvex, i.e. the surface of the lens 40 facing the first polarization conversion element 30 and the surface of the lens 40 facing the second polarization conversion element 50 are both convex. The partially transmissive and partially reflective element 90 (e.g., a light splitting film, typically a transflective film) may be provided separately from the lens 40, or may be attached to a surface of the lens 40 facing the screen, preferably to a surface of the lens 40 facing the screen, and has a transmittance of 30% to 70%, and more preferably 40% to 60%. The second polarization conversion element 50 is specifically a Quarter Wave Plate (QWP), and 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, and is preferably the same as that of the first polarization conversion element 30. The optical axis direction of the second polarization conversion element 50 is generally two, one is parallel to the first polarization conversion element 30, and the other is perpendicular to the first polarization conversion element 30. When the first scheme is adopted, the transmission axis of the polarization beam splitter 60 (PBS) is parallel to the polarizing member 20, and when the second scheme is adopted, the transmission axis of the polarization beam splitter 60 is perpendicular to the polarizing member 20. With this configuration, the polarization splitting element 60 can reflect the polarized light that is directly transmitted, thereby achieving the effect of folding the optical path. The polarization splitting element 60 may be a bragg-type reflective polarizer or a wire grid-type reflective polarizer.
In the above folded light path structure, the specific directions of the light rays are as follows: light of a pixel on the display screen 10 is polarized into linear polarization by the polarizer 20, and then is changed into circular polarization after passing through the first polarization conversion element 30, and then is changed into linear polarization again after continuously passing through the second polarization conversion element 50, at this time, the polarization direction is perpendicular to the transmission axis of the polarization splitting element 60, so that the light is reflected, and passes through the second polarization conversion element 50 for the second time, and the reflected light is reflected when reaching the partial transmission partial reflection element 90, and simultaneously, due to half-wave loss caused by reflection, the chirality of the circular polarization is reversed, so that the polarization state of the light after passing through the second polarization conversion element 50 for the third time is orthogonal to the polarization state after passing through the second polarization conversion element 50 for the first time, and thus the light can be transmitted by the polarization splitting element 60, and a main image is.
The ghost reduction display optical system of the present invention will be specifically described on the basis of the basic folded optical path described above, and in the embodiment of the present invention, the lens 40 is disposed on the side of the partially transmissive partially reflective element 90 facing away from the display screen; the lens 40 is attached to the second polarization conversion element 50, and/or the lens 40 is attached to the polarization beam splitting element 60; the second polarization conversion element 50 and the polarization beam splitting element 60 are arranged at intervals, a substrate 70 is arranged on the surface of the second polarization conversion element 50 exposed to the air, and an antireflection film 71 is arranged on the substrate 70.
Specifically, the above structure includes at least four cases:
first, the lens 40 is disposed between the partially transmissive 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 surface of the second polarization conversion element 50 facing the polarization beam splitter element 60 is provided with the substrate 70 and the antireflection film 71.
Secondly, the lens 40 is disposed between the second polarization conversion element 50 and the polarization beam splitter 60, the lens 40 and the second polarization conversion element 50 are disposed in a laminating manner, the lens 40 and the polarization beam splitter 60 are disposed at an interval, and the surface of the second polarization conversion element 50 facing the first polarization conversion element 30 is provided with the substrate 70 and the antireflection film 71.
Thirdly, the lens 40 is disposed between the second polarization conversion element 50 and the polarization beam splitter 60, the lens 40 is simultaneously attached to the second polarization conversion element 50 and the polarization beam splitter 60, and the surface of the second polarization conversion element 50 facing the first polarization conversion element 30 is provided with a substrate 70 and an antireflection film 71.
Fourthly, the lens 40 is arranged on one side of the polarization beam splitting element 60 departing from the second polarization conversion element 50, and the lens 40 and the polarization beam splitting element 60 are attached; when the second polarization conversion element 50 is attached to the partially transmissive and partially reflective element 90, the substrate 70 and the antireflection film 71 are disposed on the surface of the second polarization conversion element 50 facing the polarization beam splitter element 60; when the second polarization conversion element 50 and the polarization splitting element 60 are attached to each other, the substrate 70 and the antireflection film 71 are disposed on the surface of the second polarization conversion element 50 facing the first polarization conversion element 30.
The second polarization conversion element 50 and the polarization splitting element 60 may be spaced apart from each other by the lens 40 or by air. When the lens 40 is attached to the second polarization conversion element 50 or the lens 40 is attached to the polarization splitting element 60, an air space is provided between the second polarization conversion element 50 and the polarization splitting element 60. When the lens 40 is attached to the second polarization conversion element 50 and the polarization splitting element 60 at the same time, the second polarization conversion element 50 and the polarization splitting element 60 are spaced apart from each other by the lens 40.
It is understood that the lens 40 is disposed adjacent to the second polarization conversion element 50, or the lens 40 is disposed adjacent to the polarization splitting element 60, or the lens 40 is disposed adjacent to both the second polarization conversion element 50 and the polarization splitting element 60, that is, the lens 40 is in direct contact with one or both of the adjacent elements, and there is no air separation between the lens 40 and the adjacent element adjacent thereto, so that the ghost image caused by the fresnel reflection at the corresponding interface can be reduced. Meanwhile, a substrate 70 and an antireflection film 71 disposed on the substrate 70 are disposed on the surface of the second polarization conversion element 50 exposed to air, and the antireflection film 71, also called an antireflection film, has the main functions of reducing the reflected light from the optical surface and increasing the light transmittance, so as to further reduce the ghost phenomenon caused by fresnel reflection. In summary, the lens 40 and the second polarization conversion element 50 are attached to each other, and/or the polarization beam splitter 60 is attached to each other, and the substrate 70 and the antireflection film 71 are disposed on the surface of the second polarization conversion element 50 exposed to the air, so that the ghost phenomenon caused by fresnel reflection can be greatly reduced, and the image quality of the display optical system can be improved.
In practice, if an anti-reflection (AR) film is directly plated on the surface of the second polarization conversion element 50 facing the polarization beam splitter 60, the surface reflection is usually between 0.5% and 1%, and the dispersion performance is poor, so that an obvious color cast phenomenon is easily generated, and high reliability cannot be obtained. In this embodiment, a substrate 70 is additionally disposed on the surface of the second polarization conversion element 50 facing the polarization beam splitting element 60, and then an anti-reflection (AR) film is plated on the surface of the substrate 70 facing the polarization beam splitting element 60, so that the surface reflectivity can be significantly reduced, for example, 0.3%, and the reliability is higher. Therefore, compared with directly plating the antireflection film 71 on the surface of the second polarization conversion element 50, in the embodiment, the ghost can be further reduced by 50% to 70%, and the effect of reducing the ghost is more obvious.
It should be noted that the distances between any two elements of 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 splitter element 60 are not limited in the present invention, and may be set according to actual needs. For example, the pitch of the lens 40 and the polarization splitting element 60 may be determined according to the optical design of the main image. Therefore, the technical scheme can meet the requirements of diopter adjustment and imaging quality of optical design, avoids the adverse factors of thicker lens 40, increased weight and the like, and is suitable for popularization and application in products. Therefore, the display optical system 100 for reducing ghosting also has a characteristic of light weight, and can satisfy the requirement of a Head Mounted Display (HMD) device for weight.
In an embodiment of the invention, referring to fig. 3 to 5, the lens 40 is disposed between the partially transmissive partially reflective element 90 and the second polarization conversion element 50, the lens 40 is simultaneously attached to the partially transmissive partially reflective element 90 and the second polarization conversion element 50, an air space exists between the second polarization conversion element 50 and the polarization splitting element 60, and the surface of the second polarization conversion element 50 facing the polarization splitting element 60 and the surface of the polarization splitting element 60 facing the second polarization conversion element 50 are both provided with the substrate 70 and the antireflection film 71.
Wherein the residue formed by the interface reflection of the rear surface of the substrate 70 (i.e., toward the polarization splitting element 60)The remaining ghost paths are shown in FIG. 2 and have a ratio RR relative to the principal imagepcos2δ, where R is the reflectance of the partially transmissive partially reflective element 90, Rp is the reflectance of the polarization splitting element 60 in the transmission axis direction, and cos δ is the light leakage caused by the retardation of the second polarization conversion element 50 deviating from the quarter optical path.
In this embodiment, the lens 40 is in direct contact with the partially transmissive partially reflective element 90, and the lens 40 is in direct contact with the second polarization conversion element 50, so that no air isolation exists between the lens 40 and the partially transmissive partially reflective element 90, and between the lens 40 and the second polarization conversion element 50, which can reduce the ghost image caused by the fresnel reflection at the corresponding interface; meanwhile, the surface of the second polarization conversion element 50 exposed in the air (i.e., the surface facing the polarization splitting element 60) and the surface of the polarization splitting element 60 exposed in the air (i.e., the surface facing the second polarization conversion element 50) are both provided with the substrate 70 and the antireflection film 71, the substrate 70 can significantly reduce the surface reflectivity, and the antireflection film 71 has higher reliability, and the antireflection film 71 can further reduce the ghost phenomenon generated by fresnel reflection, thereby improving the image quality of the display optical system. In addition, the distance between the lens 40 and the polarization beam splitter 60 can be determined according to the optical design of the main image to meet the diopter adjustment and the requirements of the optical design for the image quality.
Further, referring to fig. 4 to 5, 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 splitting element 60.
In this embodiment, the substrate 70 has no focal power, that is, the curvatures of the front and back surfaces of the substrate 70 are the same, so that the direction of light in the original optical path structure is not affected, thereby ensuring the normal operation of the original optical path structure and ensuring the optical performance of the original optical path structure.
Further, referring to fig. 4 to 5, 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 lens 40 facing the second polarization conversion element 50.
Specifically, the second polarization conversion element 50 (for example, a quarter-wave plate) may be formed by crystal, polymer stretching, liquid crystal coating, or the like, and preferably has a film form such as polymer stretching and liquid crystal coating, so as to be conveniently attached to curved surfaces of lenses with different curvature radii. When the second polarization conversion element 50 is attached to the surface of the lens 40, the second polarization conversion element 50 can be adapted to the shape of the lens 40. Moreover, in the present embodiment, the curvature of the front and back surfaces of the substrate 70 is also the same as the curvature of the back surface of the lens 40 (i.e. the surface facing the second polarization conversion element 50), so that the substrate 70 can be well glued with the second polarization conversion element 50 on the back surface of the lens 40, and the light direction in the original light path structure is not affected, thereby ensuring the imaging quality.
In another embodiment of the present invention, referring to fig. 6, the surface of the substrate 70 facing the second polarization conversion element 50 is a plane.
In the case where the rear surface of the lens 40 (i.e., the surface facing the second polarization conversion element 50) is nearly planar, for example, R >400mm, the substrate 70 may be considered to be a planar element, i.e., the front and rear surfaces of the substrate 70 (i.e., the surfaces facing the second polarization conversion element 50 and the polarization splitting element 60) are both planar, and when the diameter reaches 40mm, the edge gap is less than 0.5mm, so as to facilitate filling and curing of the optical cement, the optical cement is preferably an index matching material, and the filled combined lens is equivalent to a lens formed by an index matching material and is cemented with the lens 40. Thus, the effect of reducing the ghost image can be realized, the process difficulty and the manufacturing cost can be reduced by the structure, but the influence brought by the cemented lens needs to be considered in the imaging design.
Optionally, the substrate 70 has a dispersion characteristic opposite to that of the lens 40.
By selecting a suitable material for the substrate 70, the chromatic aberration of the system can be additionally corrected without affecting the existing optical performance. Specifically, the substrate 70, which is flat or without diopter (i.e., the curvatures of the front and rear surfaces are the same), has a positive positional chromatic aberration, which is related to the refractive index, the thickness and the abbe number, and the convex lens 40 has a negative positional chromatic aberration, so that an appropriate material and thickness can be selected based on a corresponding chromatic aberration calculation formula, such as a primary seidel aberration and a high-order chromatic aberration, so that the display optical system has a more ideal chromatic aberration expression. In the present embodiment, chromatic aberration of the lens 40 is compensated by the substrate 70 having the opposite dispersion characteristic to that of the lens 40, and chromatic aberration can be effectively eliminated.
Further, an optical paste 80 is filled between the lens 40 and the second polarization conversion element 50.
In this embodiment, the lens 40 and the second polarization conversion element are bonded together by an optical adhesive 80. The optical adhesive 80 (adhesive for bonding optical parts) is a special adhesive for bonding transparent optical parts, and is required to be colorless and transparent, have a light transmittance of 90% or more, have good bonding strength, be curable at room temperature or at intermediate temperature, and have the characteristics of small curing shrinkage and the like. Adhesives such as silicone, acrylic, unsaturated polyester, polyurethane, epoxy and the like can be used to bond the optical parts. The optical adhesive 80 is a polymer having optical properties similar to those of optical parts and excellent adhesive properties. The optical glue 80 may be selectively coated on the rear surface of the lens 40 (i.e., the surface facing the second polarization conversion element 50), or may be selectively coated on the front surface of the second polarization conversion element 50 (i.e., the surface facing the lens 40), preferably coated on the second polarization conversion element 50, because the second polarization conversion element 50 (e.g., the quarter-wave plate) is soft as a whole, the second polarization conversion element 50 may be in a planar state before the second polarization conversion element 50 is attached to the lens 40, and after the optical glue 80 is coated on the front surface of the second polarization conversion element 50, 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, so that better uniformity and flatness can be achieved. Meanwhile, a bubble removing machine is required to perform vacuum bubble removing operation to prevent bubbles in the gap between the second polarization conversion element 50 and the lens 40 from scattering the imaging light when the second polarization conversion element and the lens are bonded.
Further, an optical paste 80 is filled between the second polarization conversion element 50 and the substrate 70.
In this embodiment, the second polarization conversion element 50 and the substrate 70 are also bonded together by the optical adhesive 80. The optical adhesive 80 may be selectively coated on the front surface of the substrate 70 (i.e., the surface facing the second polarization conversion element 50), or may be selectively coated on the rear surface of the second polarization conversion element 50 (i.e., the surface facing the polarization splitting element 60), preferably on the rear surface of the second polarization conversion element 50, because the second polarization conversion element 50 (e.g., the quarter-wave plate) is soft as a whole, the second polarization conversion element 50 may be in a planar state before the second polarization conversion element 50 is attached to the lens 40, after the optical adhesive 80 is coated on the front and rear surfaces of the second polarization conversion element 50, 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, and finally, the substrate 70 is attached to the rear surface of the second polarization conversion element 50, which can achieve better uniformity and flatness. Meanwhile, a bubble removing machine is required to perform vacuum bubble removing operation to prevent the bubble residue in the gap between the second polarization conversion element 50 and the substrate 70 from scattering the imaging light when the second polarization conversion element and the substrate 70 are bonded.
Specifically, the optical cement 80 employs an index matching material.
Matching here means that the difference in refractive index between the materials at the two sides of the interface is reduced, thereby minimizing the loss of reflected light. Index matching is an important optical means, and aims to make the refractive index of a contact substance conform to a certain rule so as to reduce the reflection of light or increase the transmission of light. Interface reflection inside the optical system can be reduced by selecting the refractive index matching material, so that ghost is reduced, and imaging quality is improved.
Alternatively, the substrate 70 may be made of glass, resin, or an optical film.
In this embodiment, the material of the substrate 70 is preferably glass. As can be seen from the coating process, a better coating effect can be generally achieved at a high temperature, because the substrate is pretreated, the substrate is firstly activated, the chemical bond between the substrate and the coating material is increased, the bonding force between the coating and the substrate is improved, and the absorption of the substrate impurity gas and the high refractive index coating material is reduced, in addition, some low-refraction materials such as magnesium fluoride (MgF2) used as the anti-reflection film 71 are only suitable for high-temperature deposition, and glass generally has a better high-temperature resistance characteristic, so that compared with resin and optical films, the substrate 70 is made of glass, and can achieve lower interface reflection and better reliability of the coating material.
The invention further provides a head-mounted display device for reducing ghosting, which includes a head-mounted main body and a display optical system 100 for reducing ghosting, where the display optical system 100 for reducing ghosting is disposed in the head-mounted main body, and the specific structure of the display optical system 100 for reducing ghosting refers to the above embodiments.
Wherein, wear the main part and can include the frame that is suitable for wearing at user's head, be used for adjusting the elasticity adjusting device of frame constraint degree to and be connected with the display optical system in order to carry out the control system etc. that controls display screen 10, wear the specific structure and the setting of main part and can adopt prior art, no longer describe here.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the contents of the present specification and the accompanying drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (10)
1. A display optical system for reducing ghost is characterized by comprising a display screen, a polarizing piece, a first polarization conversion element, a partial transmission partial reflection element, a second polarization conversion element and a polarization beam splitting element which are sequentially arranged;
the display optical system further comprises a lens arranged on one side of the partially transmitting and partially reflecting element away from the display screen; the lens is attached to the second polarization conversion element, and/or the lens is attached to the polarization splitting element; the second polarization conversion element and the polarization light splitting element are arranged at intervals, a substrate is arranged on the surface, exposed to the air, of the second polarization conversion element, and an antireflection film is arranged on the substrate.
2. The display optical system according to claim 1, wherein the lens is disposed between the partially transmissive partially reflective element and the second polarization conversion element, the lens is disposed in close contact with the partially transmissive partially reflective element and the second polarization conversion element, an air space is present between the second polarization conversion element and the polarization splitting element, and the substrate and the antireflection film are disposed on a surface of the second polarization conversion element facing the polarization splitting element and a surface of the polarization splitting element facing the second polarization conversion element.
3. The ghost-reducing display optical system according to claim 2, wherein a curvature of a surface of the substrate facing the second polarization conversion element is the same as a curvature of a surface of the substrate facing the polarization splitting element.
4. The ghost-reducing display optical system according to claim 3, wherein a curvature of a surface of the substrate facing the second polarization conversion element is the same as a curvature of a surface of the lens facing the second polarization conversion element.
5. The ghost-reducing display optical system according to claim 3, wherein a surface of the substrate facing the second polarization conversion element is a plane.
6. The ghost-reducing display optical system of claim 3, wherein the substrate has a dispersion characteristic opposite to that of the lens.
7. The ghost-reducing display optical system according to any one of claims 2 to 6, wherein an optical glue is filled between the lens and the second polarization conversion element.
8. The ghost-reducing display optical system according to any one of claims 2 to 6, wherein an optical paste is filled between the second polarization conversion element and the substrate.
9. The ghost-reducing display optical system according to claim 7 or 8, wherein the optical paste is made of an index matching material.
10. A head-mounted display device with reduced ghosting, comprising:
a head-mounted body; and
the ghost-reducing display optical system of any one of claims 1-9 disposed within the head-mounted body.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011161123.5A CN112305763A (en) | 2020-10-26 | 2020-10-26 | Display optical system for reducing ghost and head-mounted display device |
| PCT/CN2021/111747 WO2022088836A1 (en) | 2020-10-26 | 2021-08-10 | Display optical system and head-mounted display apparatus which reduce ghosting |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011161123.5A CN112305763A (en) | 2020-10-26 | 2020-10-26 | Display optical system for reducing ghost and head-mounted display device |
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| Publication Number | Publication Date |
|---|---|
| CN112305763A true CN112305763A (en) | 2021-02-02 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202011161123.5A Withdrawn CN112305763A (en) | 2020-10-26 | 2020-10-26 | Display optical system for reducing ghost and head-mounted display device |
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| Country | Link |
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| CN (1) | CN112305763A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2022088836A1 (en) * | 2020-10-26 | 2022-05-05 | 深圳惠牛科技有限公司 | Display optical system and head-mounted display apparatus which reduce ghosting |
| CN114935822A (en) * | 2022-06-15 | 2022-08-23 | 业成科技（成都）有限公司 | Optical system |
-
2020
- 2020-10-26 CN CN202011161123.5A patent/CN112305763A/en not_active Withdrawn
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2022088836A1 (en) * | 2020-10-26 | 2022-05-05 | 深圳惠牛科技有限公司 | Display optical system and head-mounted display apparatus which reduce ghosting |
| CN114935822A (en) * | 2022-06-15 | 2022-08-23 | 业成科技（成都）有限公司 | Optical system |
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Application publication date: 20210202 |