PBS prism and head-mounted display device
By setting two layers of flat glass and PBS film in the PBS assembly, the problem of insufficient polarization effect of single layer PBS film is solved, and the extinction ratio and imaging quality of the PBS assembly are significantly improved.
Patent Information
- Application Number
- CN202421840591.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-31
- Publication Date
- 2025-05-06
- Estimated Expiration
- 2034-07-31
AI Technical Summary
The existing PBS components have insufficient polarization effect of the single-layer PBS film, which leads to a relatively low extinction, which in turn affects the imaging quality.
A PBS prism is designed, and the flatness and uniformity of the PBS film are improved by setting two layers of flat glass between the two triangular prisms, thereby improving the extinction ratio of the PBS component.
By improving the performance of the PBS film and optimizing the beam incident angle, the extinction ratio of the PBS component is significantly improved, thereby improving the imaging quality.
Smart Images
Figure CN222838202U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of optical equipment, in particular to a PBS prism and a head-mounted display device. Background Art
[0002] With the advancement of imaging technology, people's demand for immersive experience is getting higher and higher. In recent years, the development of VR / AR technology has gradually satisfied people's pursuit of visual experience. Head-mounted devices can free people's hands, reduce dependence on screens, and create better visual effects. For head-mounted devices, near-eye display is the key to its technology, and imaging quality and thinness are the main considerations.
[0003] At present, the main AR optical machine miniaturization solutions are micro LED solutions and LCOS (Liquid Crystal on Silicon) solutions. Although the micro LED solution can achieve a smaller volume, it is limited by the cost and mass production of the color solution. The LCOS solution can achieve a higher resolution color display under a larger FOV, and the cost and mass production are controllable. The development and cost of the high performance of the optical machine using the LCOS solution are mainly limited by the performance and cost of the PBS component (polarization beam splitter component).
[0004] The existing PBS component is usually a cubic prism formed by splicing two triangular prisms, with only one layer of PBS film (polarization splitter film) arranged between the two triangular prisms. The PBS film is used to separate light beams according to the polarization state of light (such as s-polarized light and p-polarized light). However, the single-layer PBS film is effective for the polarization effect of p-polarized light and s-polarized light, resulting in relatively low extinction of the PBS component and poor imaging quality. Utility Model Content
[0005] The main purpose of the utility model is to provide a PBS prism and a head-mounted display device, aiming to solve the problem that the extinction of a single-layer PBS film of an existing PBS component is relatively low, resulting in poor imaging quality.
[0006] To achieve the above-mentioned purpose, the PBS prism proposed by the utility model is characterized by comprising:
[0007] Flat glass, the number of the flat glass is two, and the two flat glass are connected by a PBS film;
[0008] Two triangular prisms, the two triangular prisms have the same structure and the cross-section is a right triangle, each of the triangular prisms includes two right-angled sides and one long side, the two triangular prisms are respectively bonded to the side of the two flat glasses away from the PBS film, and the long side of each triangular prism is connected to the flat glass.
[0009] In one embodiment, the cross section of the triangular prism is an isosceles right triangle.
[0010] In one embodiment, the line connecting the endpoints of the right angles of the two triangular prisms is used as a first symmetry axis, and the PBS prisms are symmetrically arranged along the first symmetry axis; the PBS film is used as a second symmetry axis, and the PBS prisms are symmetrically arranged along the second symmetry axis.
[0011] In one embodiment, the surface accuracy of the right-angled side and the long side of the triangular prism is 0.25 aperture to 0.5 aperture.
[0012] In one embodiment, two ends of the long side of each of the triangular prisms are aligned with two ends of the flat glass, and two ends of the flat glass are aligned with two ends of the PBS film.
[0013] In one embodiment, the refractive index of the triangular prism is greater than the refractive index of the flat glass, and the refractive index of the flat glass is the same as the refractive index of the PBS film.
[0014] In one embodiment, the triangular prism is connected to the flat glass via optical glue, and / or the flat glass is connected to the PBS film via optical glue.
[0015] In one embodiment, the thickness of the flat glass is 0.15 mm to 0.5 mm, and / or the thickness of the PBS film is 0.08 mm to 0.1 mm.
[0016] In one embodiment, each of the triangular prisms is formed by grinding a glass substrate separately, and the two glass substrates are disposed separately.
[0017] The utility model also provides a head-mounted display device, which is applied with the above-mentioned PBS prism.
[0018] The technical solution of the utility model is to arrange two layers of flat glass between two triangular prisms, and to arrange a PBS film between the two layers of flat glass. The smooth surface of the flat glass helps to improve the flatness and uniformity of the PBS film, thereby improving the performance of the PBS film, so as to improve the extinction ratio of the PBS component. At the same time, the incident angle of the light beam on the PBS film is optimized by the flat glass, thereby further improving the extinction ratio of the PBS component. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.
[0020] Figure 1 This is a structural schematic diagram of the PBS prism provided by the utility model.
[0021] Description of Figure Numbers:
[0022] 100, PBS prism; 11, flat glass; 12, PBS film; 2, triangular prism; 21, right-angled side; 22, long side.
[0023] The realization of the purpose, functional features and advantages of the utility model will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION
[0024] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.
[0025] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back...), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indications will also change accordingly.
[0026] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the utility model, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of the features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or solutions that satisfy both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the utility model.
[0027] The existing PBS assembly usually adheres two glass substrates to the two sides of the PBS film, and then grinds the glass substrate into a triangular prism with a right-angled triangle cross section. The two right-angled sides of the triangular prism serve as the incident end and the output end of the light. Therefore, the surface accuracy of the surface where the right-angled sides are located has a great influence on the imaging accuracy. When the glass substrate is grinded in the prior art, since the PBS film and the glass substrate are bonded together, there will be a certain amount of shaking and deviation, which will affect the surface accuracy of the triangular prism during the grinding process, resulting in the surface accuracy of the triangular prism can only reach 1.0 aperture to 1.5 aperture. The surface accuracy of the triangular prism is insufficient, resulting in poor imaging effect.
[0028] In order to solve the above problems, the present invention provides a PBS prism 100 .
[0029] See also Figure 1 The PBS prism 100 includes a flat glass 11 and two triangular prisms 2. The number of the flat glass 11 is two, and the two flat glass 11 are connected by a PBS film 12. The two triangular prisms 2 have the same structure and their cross-sections are both right-angled triangles. Each triangular prism 2 includes two right-angled sides 21 and a long side 22. The two triangular prisms 2 are respectively bonded to the sides of the two flat glass 11 away from the PBS film 12, and the long side 22 of each triangular prism 2 is connected to the flat glass 11.
[0030] The technical solution of the utility model is to set two layers of flat glass 11 between two triangular prisms 2, and set a PBS film 12 between the two layers of flat glass 11. The smooth surface of the flat glass 11 helps to improve the flatness and uniformity of the PBS film 12, thereby improving the performance of the PBS film 12, so as to improve the extinction ratio of the PBS component 1. At the same time, the incident angle of the light beam on the PBS film 12 is optimized by the flat glass 11, so as to further improve the extinction ratio of the PBS component 1.
[0031] Specifically, the cross section of the triangular prism 2 is an isosceles right triangle. The main function of the PBS prism 100 is to separate the incident light beam according to the polarization state. The isosceles right triangle prism can provide 45 degrees of incident and exit angles to ensure appropriate reflection and transmission performance.
[0032] Furthermore, the PBS prism 100 is symmetrically arranged along the first symmetry axis, with the line connecting the endpoints of the right angles of the two triangular prisms 2 being the first symmetry axis, and the PBS film 12 being the second symmetry axis, and the PBS prism 100 is symmetrically arranged along the second symmetry axis. The PBS prism 100 is arranged along the first symmetry axis and the second symmetry axis, respectively. The symmetrically arranged PBS prism 100 can maintain the balance of the optical path, ensuring that the light beam does not deviate or deflect when passing through the system, and the symmetrical arrangement can effectively reduce the error accumulation in the optical path, and improve the stability and accuracy of the optical path transmission.
[0033] In one embodiment, the surface accuracy of the right-angle side 21 and the long side 22 of the triangular prism 2 is 0.25 aperture to 0.5 aperture. In the prior art, the surface accuracy of the triangular prism 2 can only reach 1.0 aperture to 1.5 aperture. The surface accuracy of the triangular prism 2 is improved to 0.25 aperture to 0.5 aperture by split grinding, thereby improving the imaging accuracy and the imaging effect.
[0034] In one embodiment, the two ends of the long side 22 of each triangular prism 2 are aligned with the two ends of the flat glass 11, and the two ends of the flat glass 11 are aligned with the two ends of the PBS film 12. The long side 22 of the triangular prism 2, the edges of the flat glass 11 and the PBS film 12 are all aligned, which can ensure that the optical paths of the incident light beam and the outgoing light beam remain accurate, thereby reducing the optical path error caused by the misalignment between the optical elements, thereby improving the imaging accuracy.
[0035] In one embodiment, the refractive index of the triangular prism 2 is greater than the refractive index of the flat glass 11, and the refractive index of the flat glass 11 is the same as the refractive index of the PBS film 12. The equivalent air gap of the PBS prism 100 = 2d / n, where d is the length of the right-angle side 21 of the triangular prism 2, n is the refractive index, n1 is the refractive index of the triangular prism 2, and n2 is the refractive index of the flat glass 11. When the prism prepared by the technical solution of the present application is adopted, the equivalent air gap is 2d / n1. Compared with 2d / n2 of the traditional PBS prism 100, when the length of the side of the triangular prism 2 remains unchanged, the equivalent air gap is smaller, so that the effective focal length f of the lens using the same architecture can be smaller, thereby achieving a larger FOV.
[0036] Specifically, the material of the flat glass 11 is H-K9L, and the material of the triangular prism 2 is H-ZF52. The refractive index of the flat glass 11 can be lower than the refractive index of the triangular prism 2, and the effect is optimal.
[0037] In one embodiment, the triangular prism 2 is connected to the flat glass 11 by optical glue, and the flat glass 11 is connected to the PBS film 12 by optical glue. The optical glue is usually designed to have a refractive index close to that of the flat glass 11 or the prism, which reduces the reflection loss of light at the material interface and improves the optical transmission efficiency of the system. At the same time, the optical glue can maintain high transparency and uniformity during curing without introducing bubbles or impurities, which is very critical for high-quality optical imaging and transmission.
[0038] In one embodiment, the thickness of the flat glass 11 is 0.15 mm to 0.5 mm, and / or the thickness of the PBS film 12 is 0.08 mm to 0.1 mm. The glass material itself will cause reflection and absorption of light. The thinner flat glass 11 reduces the path of light transmission in the glass, thereby reducing reflection and absorption losses and improving the optical efficiency of the system. The thickness of the PBS film 12 determines its transmission and reflection properties. When the thickness of the PBS film 12 is 0.08 mm to 0.1 mm, high transmittance and high reflectivity can be obtained, thereby optimizing the separation and transmission of light beams. Specifically, the PBS film 12 is a 3M film, and its thickness is 0.082 mm.
[0039] It is understandable that when the existing PBS assembly is used to grind the glass substrate to form a triangular prism, since the PBS film and the glass substrate are bonded together, there will be a certain amount of shaking and deviation, which will affect the surface accuracy of the triangular prism during the grinding process, resulting in the surface accuracy of the triangular prism only reaching 1.0 aperture to 1.5 aperture. The surface accuracy of the triangular prism is insufficient, resulting in poor imaging effects.
[0040] Therefore, in the scheme of the present application, each of the triangular prisms is formed by grinding a glass substrate separately, and the two glass substrates are arranged in a split type, so that the triangular prism 2 can be formed by grinding two separately arranged glass substrates separately, and the triangular prism 2 is connected to the flat glass 11, so that the glass substrate can be ground into the triangular prism 2 and then installed, so that the glass substrate can be ground into a triangular prism 2 with a surface accuracy far higher than that of the prior art, thereby improving the surface accuracy and achieving good imaging effect. At the same time, since the glass substrate is ground independently, it will not cause friction to the PBS film 12, thereby improving the reflected wavefront of the PBS film 12, thereby making the imaging performance more stable.
[0041] The present invention also provides a head mounted display device, which uses the above-mentioned PBS prism 100. The specific structure of the PBS prism 100 refers to the above-mentioned embodiment. Since the present head mounted display device adopts all the technical solutions of all the above-mentioned embodiments, it at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be described one by one here.
[0042] The above description is only an exemplary embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.
Claims
1. A PBS prism, characterized in that: include: Flat glass, the number of the flat glass is two, and the two flat glass are connected by a PBS film; Two triangular prisms, the two triangular prisms have the same structure and the cross-section is a right triangle, each of the triangular prisms includes two right-angled sides and one long side, the two triangular prisms are respectively bonded to the side of the two flat glasses away from the PBS film, and the long side of each triangular prism is connected to the flat glass.
2. The PBS prism according to claim 1, wherein: The cross section of the triangular prism is an isosceles right triangle.
3. The PBS prism according to claim 2, characterized in that: The PBS prisms are symmetrically arranged along the first symmetry axis, with the line connecting the endpoints of the right angles of the two triangular prisms being the first symmetry axis; and the PBS film being the second symmetry axis, with the PBS prisms being symmetrically arranged along the second symmetry axis.
4. The PBS prism according to claim 1, wherein: The surface accuracy of the right-angled side and the long side of the triangular prism is 0.25 aperture to 0.5 aperture.
5. The PBS prism according to claim 1, wherein: Both ends of the long side of each of the triangular prisms are aligned with both ends of the flat glass, and both ends of the flat glass are aligned with both ends of the PBS film.
6. The PBS prism according to any one of claims 1 to 5, characterized in that The refractive index of the triangular prism is greater than the refractive index of the flat glass, and the refractive index of the flat glass is the same as the refractive index of the PBS film.
7. The PBS prism according to any one of claims 1 to 5, characterized in that The triangular prism is connected to the flat glass via optical glue, and / or the flat glass is connected to the PBS film via optical glue.
8. The PBS prism according to any one of claims 1 to 5, characterized in that The thickness of the flat glass is 0.15 mm to 0.5 mm, and / or the thickness of the PBS film is 0.08 mm to 0.1 mm.
9. The PBS prism according to any one of claims 1 to 5, characterized in that: Each of the triangular prisms is formed by grinding a glass substrate separately, and the two glass substrates are arranged in a split type.
10. A head mounted display device, characterized in that: A PBS prism as claimed in any one of claims 1 to 9 is used.