Near-to-eye display optical system

Abstract

The invention discloses a near-to-eye display optical system, and belongs to the technical field of optical display. Comprising an image source, a first plane spectroscope, a concave reflector, a second concave spectroscope and a polarization dimming element which are sequentially arranged along a light path, and left-hand circularly polarized light emitted by the image source is turned back for multiple times through the first plane spectroscope, the concave reflector, the second concave spectroscope and the polarization dimming element. The polarized light is converted into right-handed circularly polarized light, left-handed circularly polarized light, S-linearly polarized light, left-handed circularly polarized light and P-linearly polarized light in sequence, and finally, the P-linearly polarized light is emitted by the polarization dimming element to enter human eyes; outside scene light rays sequentially pass through the first plane spectroscope, the second concave spectroscope and the polarization dimming element and then reach human eyes, and overlapping display of a display picture and an outside scene is achieved. The near-to-eye display device solves the problems of external scene dislocation, large size, heavy weight and the like of the existing near-to-eye display device for large-view-field penetration display.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical display, and in particular relates to a near-eye display optical system. Background Art

[0002] In recent years, with the great progress of science and technology, near-eye display devices have made great progress, and large field of view display is an urgent need for augmented reality display. The current mainstream augmented reality display solutions (waveguide display, Birdbath, etc.) have a field of view angle between 40° and 50°. There are many problems for ultra-large field of view display (greater than 80°). For example, the free-form surface display solution can achieve a 120° field of view, but there is a serious problem of misalignment of the external scene. The single goggle reflection solution can also achieve a large field of view, and the comfort of observing the external scene is improved compared to the free-form surface solution, but it has problems such as bulky size and heavy weight, which makes it difficult to meet the use requirements. Summary of the invention

[0003] Technical issues to be solved:

[0004] In order to avoid the shortcomings of the prior art, the present invention provides a near-eye display optical system, which is an augmented reality display optical system configuration with a large field of view and a compact structure, capable of multi-length folding of the image source, and finally reaching the human eye together with the external scene light, so as to realize the superposition display of the display image and the external scene. The present invention provides a technical solution for a miniaturized, lightweight, and ergonomic helmet display, solving the problems of external scene misalignment, large size, and heavy weight existing in the current near-eye display device for large field of view penetration display.

[0005] The technical solution of the present invention is: a near-eye display optical system, comprising an image source, a first plane beam splitter, a concave reflector, a second concave beam splitter, and a polarization dimming element arranged in sequence along an optical path, wherein the left-handed circularly polarized light emitted by the image source is folded multiple times by the first plane beam splitter, the concave reflector, the second concave beam splitter, and the polarization dimming element, and is converted into right-handed circularly polarized light, left-handed circularly polarized light, S-linearly polarized light, left-handed circularly polarized light, and P-linearly polarized light in sequence, and finally the polarization dimming element emits P-linearly polarized light to be incident on a human eye;

[0006] The external scene light passes through the first plane beam splitter, the second concave beam splitter, and the polarization dimming element in sequence before reaching the human eye, thereby realizing the superposition display of the display image and the external scene.

[0007] A further technical solution of the present invention is that: the image source includes an OLED image source, a linear polarizer, and a first quarter wave plate in the order of superposition, the natural light emitted by the OLED image source is converted into P polarized light after passing through the linear polarizer, and the P polarized light is converted into a left-handed circularly polarized light beam after passing through the first quarter wave plate;

[0008] Alternatively, the image source includes an LCD image source and a first quarter wave plate in a superimposed order.

[0009] A further technical solution of the present invention is: the first plane beam splitter forms an angle of 40° to 50° with the plane where the image source is located, has a thickness between 1 and 5 mm, and is made of optical glass or optical resin; the plane adjacent to the image source is coated with a beam splitter film, and the plane away from the image source is coated with an anti-reflection film, which is used to transmit the light beam and adjust the propagation direction of the light beam.

[0010] A further technical solution of the present invention is: the concave reflector is coated with a reflective film, the concave surface is a rotationally symmetrical spherical surface or an aspherical surface, the radius of curvature of the concave surface is between 15 mm and 35 mm, and the material is optical glass, aluminum or optical resin; its position is opposite to the image source, receives the left-handed circularly polarized light beam transmitted by the first plane beam splitter, reflects the left-handed circularly polarized light beam and converts it into a right-handed circularly polarized light beam, and then incidents on the first plane beam splitter again.

[0011] A further technical solution of the present invention is: the second concave beam splitter is arranged in the reflection light path of the first plane beam splitter, the convex surface adjacent to the first plane beam splitter is coated with a beam splitting film, and the concave surface adjacent to the polarization modulating element is coated with an anti-reflection film, which is used to transmit the left-handed circularly polarized light to the polarization modulating element, and then reflect the left-handed circularly polarized light returned by the polarization modulating element into right-handed circularly polarized light.

[0012] A further technical solution of the present invention is: the second concave beam splitter is a meniscus lens, two surfaces of which are rotationally symmetrical spherical or aspherical surfaces, the concave curvature radius is between 15mm and 30mm, the thickness is between 1 and 5mm, and the material is optical glass or optical resin.

[0013] A further technical solution of the present invention is: the polarization dimming element includes a second quarter-wave plate, a reflective polarizer, and a flat plate element arranged in sequence along the optical path, the second quarter-wave plate converts the incident left-handed circularly polarized light into S-linear polarized light, the S-linear polarized light is reflected by the reflective polarizer and then converted into left-handed circularly polarized light through the second quarter-wave plate, the left-handed circularly polarized light is then reflected by the second concave beam splitter and then converted into right-handed circularly polarized light, the right-handed circularly polarized light is converted into P-linear polarized light through the second quarter-wave plate, the P-linear polarized light is incident on the human eye after passing through the reflective polarizer and the flat plate element.

[0014] A further technical solution of the present invention is that the second quarter wave plate, the reflective polarizer and the flat plate element in the polarization modulating element are glued and fixedly connected in sequence, and the total thickness of the polarization modulating element is 1 to 5 mm.

[0015] A further technical solution of the present invention is that the distance between the exit pupil of the near-eye display optical system and the polarization dimming element along the visual horizon is not less than 6 mm.

[0016] A further technical solution of the present invention is that the distances between the image source, the first plane beam splitter, the concave reflector, the second concave beam splitter, and the polarization modulating element are set as follows:

[0017] The distance between the image source and the first plane beam splitter along the optical axis is between 8 mm and 10 mm, and the closest distance between the two is greater than 1 mm;

[0018] The distance between the first plane beam splitter and the concave reflector along the optical axis is between 13.5 mm and 16.5 mm, and the closest distance between the two is greater than 1 mm;

[0019] The distance between the first plane beam splitter and the second concave beam splitter along the optical axis is between 8 mm and 12 mm, and the closest distance between the two is greater than 1 mm;

[0020] The closest distance between the concave reflector and the second concave beam splitter is greater than 1 mm;

[0021] The distance between the second concave beam splitter and the polarization modulating element along the optical axis is between 3 mm and 5 mm, and the shortest distance between the two is greater than 1 mm.

[0022] Beneficial Effects

[0023] The beneficial effect of the present invention is that the present invention integrates the components into an integrated display optical system by designing the structural parameters and position angles of the image source, the first plane beam splitter, the concave reflector, the second concave beam splitter, and the polarization dimming element, that is, it can realize multiple folding and conversion of natural light emitted by the image source into P-linear polarized light incident on the human eye, and can also transmit the external scene light to the human eye, thereby realizing the superposition display of the display screen and the external scene. The specific advantages are as follows:

[0024] 1. Large display field of view, with a monocular display field of view of more than 80°;

[0025] 2. The light path is folded four times by using a beam splitter, a reflector and a polarization return element to optimize the direction of the light path. Combined with the secondary imaging method, the volume and length of the optical system are greatly reduced while meeting the requirements of a large field of view display. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic diagram of a novel near-eye display optical system embodiment of the present invention;

[0027] Figure 2 Schematic diagram of image source in an embodiment of the present invention;

[0028] Figure 3 A schematic structural diagram of a first plane beam splitter in an embodiment of the present invention;

[0029] Figure 4 A schematic diagram of the structure of the second concave beam splitter in an embodiment of the present invention;

[0030] Figure 5 A schematic diagram of the structure of a polarization dimming element in an embodiment of the present invention;

[0031] Explanation of the accompanying drawings: 1. Image source, 11. OLED image source, 12. Linear polarizer, 13. First quarter wave plate; 2. First plane beam splitter, 21. Anti-reflection film, 22. Beam splitter film; 3. Concave reflector, 4. Second concave beam splitter, 41. Beam splitter film, 42. Anti-reflection film; 5. Polarization modulating element, 51. Flat element, 52. Reflective polarizer, 53. Second quarter wave plate; 6. P linear polarized light, 7. Schematic diagram of external light. DETAILED DESCRIPTION

[0032] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0033] Based on the current mainstream augmented reality display solutions (waveguide display, Birdbath, etc.), the field of view is between 40° and 50°. There are many problems for ultra-large field of view displays (greater than 80°). For example, the free-form surface display solution can achieve a 120° field of view, but there is a serious problem of misalignment of the external visual scene. The single goggle reflection scheme can also achieve a large field of view, and the comfort of observing the outside scene is improved compared with the free surface scheme, but there are problems such as bulky size and heavy weight, and it is difficult to meet the use requirements. The present invention provides a near-eye display optical system, including an image source, a first plane beam splitter, a concave reflector, a second concave beam splitter, and a polarization dimming element arranged in sequence along the optical path. The left-handed circularly polarized light emitted by the image source is folded multiple times by the first plane beam splitter, the concave reflector, the second concave beam splitter, and the polarization dimming element, and is converted into right-handed circularly polarized light, left-handed circularly polarized light, S-linear polarized light, left-handed circularly polarized light, and P-linear polarized light in sequence. Finally, the polarization dimming element emits P-linear polarized light to be incident on the human eye; the outside scene light passes through the first plane beam splitter, the second concave beam splitter, and the polarization dimming element in sequence before reaching the human eye, so that the display image and the outside scene are superimposed on each other.

[0034] Specifically, the image source includes an OLED image source, a linear polarizer, and a first quarter wave plate in a superposition order, the natural light emitted by the OLED image source is converted into P polarized light after passing through the linear polarizer, and the P polarized light is converted into a left-handed circularly polarized light beam after passing through the first quarter wave plate;

[0035] Alternatively, the image source includes an LCD image source and a first quarter wave plate in a superimposed order.

[0036] Specifically, the first plane beam splitter forms an angle of 40° to 50° with the plane where the image source is located, has a thickness between 1 and 5 mm, and is made of optical glass or optical resin; the plane adjacent to the image source is coated with a beam splitter film, and the plane away from the image source is coated with an anti-reflection film, which is used to transmit the light beam and adjust the propagation direction of the light beam.

[0037] Specifically, the concave reflector is coated with a reflective film, the concave surface is a rotationally symmetrical spherical surface or an aspherical surface, the radius of curvature of the concave surface is between 15 mm and 35 mm, and the material is optical glass, aluminum or optical resin; its position is opposite to the image source, receives the left-handed circularly polarized light beam transmitted by the first plane beam splitter, reflects the left-handed circularly polarized light beam and converts it into a right-handed circularly polarized light beam, and then incidents on the first plane beam splitter again.

[0038] Specifically, the second concave beam splitter is arranged in the reflective light path of the first plane beam splitter, the convex surface adjacent to the first plane beam splitter is coated with a beam splitting film, and the concave surface adjacent to the polarization modulating element is coated with an anti-reflection film, which is used to transmit the left-handed circularly polarized light to the polarization modulating element, and then reflect the left-handed circularly polarized light returned by the polarization modulating element into right-handed circularly polarized light.

[0039] Specifically, the second concave beam splitter is a meniscus lens, two surfaces of which are rotationally symmetrical spherical or aspherical surfaces, the concave curvature radius is between 15 mm and 30 mm, the thickness is between 1 and 5 mm, and the material is optical glass or optical resin.

[0040] Specifically, the polarization dimming element includes a second quarter-wave plate, a reflective polarizer, and a flat plate element which are sequentially arranged along the optical path. The second quarter-wave plate converts the incident left-handed circularly polarized light into S-linear polarized light. The S-linear polarized light is reflected by the reflective polarizer and then converted into left-handed circularly polarized light through the second quarter-wave plate. The left-handed circularly polarized light is then reflected by a second concave beam splitter and then converted into right-handed circularly polarized light. The right-handed circularly polarized light is converted into P-linear polarized light through the second quarter-wave plate. The P-linear polarized light passes through the reflective polarizer and the flat plate element and then enters the human eye.

[0041] Specifically, the second quarter wave plate, the reflective polarizer, and the flat plate element in the polarization modulating element are glued and fixedly connected in sequence, and the total thickness of the polarization modulating element is 1 to 5 mm.

[0042] Specifically, the distance between the exit pupil of the near-eye display optical system and the polarization dimming element along the visual horizon is not less than 6 mm.

[0043] Specifically, the distances between the image source, the first plane beam splitter, the concave reflector, the second concave beam splitter, and the polarization modulating element are set as follows:

[0044] The distance between the image source 1 and the first plane beam splitter 2 along the optical axis is between 8 mm and 10 mm, preferably 9.3 mm, and the shortest distance between the image source 1 and the first plane beam splitter 2 is greater than 1 mm.

[0045] The distance between the first plane beam splitter 2 and the concave reflecting mirror 3 along the optical axis is between 13.5 mm and 16.5 mm, preferably 15 mm, and the shortest distance between the first plane beam splitter 2 and the concave reflecting mirror 3 is greater than 1 mm.

[0046] The distance between the first plane beam splitter 2 and the second concave beam splitter 4 along the optical axis is between 8 mm and 12 mm, preferably 10 mm, and the closest distance between the first plane beam splitter 2 and the second concave beam splitter 4 is greater than 1 mm.

[0047] The shortest distance between the concave reflecting mirror 3 and the second concave beam splitter 4 is greater than 1 mm.

[0048] The distance between the second concave beam splitter 4 and the polarization modulating element 5 along the optical axis is between 3 mm and 5 mm, preferably 4 mm, and the shortest distance between 4 and the polarization modulating element 5 is greater than 1 mm.

[0049] The above technical solution is further described below with reference to the accompanying drawings and examples:

[0050] A novel near-eye display optical system of the present invention can be applied to an augmented reality helmet display. When designing, factors such as the lightweight and miniaturized design of the system and compatibility with the head space are considered while ensuring the optical imaging quality.

[0051] The optical system of the present invention achieves the following optical characteristics:

[0052] Field of view: 80°;

[0053] Exit pupil diameter: 6mm;

[0054] Exit pupil distance: 10mm;

[0055] Display band: 486nm~656nm;

[0056] Weight: 10g.

[0057] Reference Figure 1 - Figure 5As shown, the optical system of this embodiment includes an image source 1, a first plane beam splitter 2, a concave reflector 3, a second concave beam splitter 4, and a polarization dimming element 5. The image source 1 is used to generate a light beam, and includes an OLED image source 11, a linear polarizer 12, and a quarter wave plate 13, which are glued together in sequence. The S2-1 surface of the first plane beam splitter is coated with an anti-reflection film 21, and the S2-2 surface is coated with a beam splitter film 22, which are used to transmit the light beam and adjust the propagation direction of the light beam; the concave reflector 3 is coated with a reflective film, which is used to reflect the light beam, the S4-1 surface of the second concave beam splitter is coated with a beam splitter film 41, and the S4-2 surface is coated with an anti-reflection film 42, which are used to transmit and reflect the light beam, and the polarization dimming element 5 includes a flat plate element 51, a reflective polarizer 52, and a quarter wave plate 53, which are glued together in sequence, and are used to reflect S polarized light and transmit P polarized light.

[0058] The method and principle of displaying images by the near-eye display optical system are as follows:

[0059] The natural light emitted by the OLED image source 11 of the image source 1 is converted into P polarized light after passing through the linear polarizer 12, and the P polarized light is converted into left-handed circularly polarized light beam after passing through the quarter-wave plate 13, and enters the first plane beam splitter 2;

[0060] The left-handed circularly polarized light beam is transmitted through the first plane beam splitter 2 and incident on the concave reflector 3. After being reflected by the concave reflector 3, it becomes right-handed circularly polarized light and is incident on the first plane beam splitter again. After being reflected by the surface S2-1 of the first plane beam splitter, it becomes left-handed circularly polarized light and is transmitted to the second concave beam splitter 4.

[0061] The left-handed circularly polarized light is transmitted through the second concave beam splitter 4 and then transmitted to the polarization modulating element 5. After passing through the quarter wave plate 53, it becomes S linear polarized light perpendicular to the vibration direction and is reflected by the reflective polarizer. After passing through the quarter wave plate 53 for the second time, it becomes left-handed circularly polarized light. After being reflected by the S4-1 surface of the second concave beam splitter, it becomes right-handed circularly polarized light and passes through the quarter wave plate 53 for the third time. The right-handed circularly polarized light becomes P linear polarized light parallel to the vibration direction.

[0062] P linear polarized light enters the human eye after passing through the reflective polarizer and flat plate elements;

[0063] The external scene light reaches the human eye after passing through the first plane beam splitter, the second concave beam splitter and the polarization dimming element, so that the display image and the external scene are superimposed on each other.

[0064] The S2 - 1 surface and the S2 - 2 surface of the first plane beam splitter 2 are planes with an inclination angle of 45° and a thickness of 1 mm, and are made of optical plastic PMMA.

[0065] The concave surface of the concave reflector 3 faces the first plane beam splitter 2, and the concave surface is a rotationally even-order symmetrical aspheric surface, the curvature radius of the concave surface base is 25 mm, and the material is an aluminum reflector. The even-order aspheric surface is expressed as:

[0066]

[0067] In the formula, parameter c is the curvature corresponding to the radius, r is the radius of the curved surface, and k is the conic quadratic curve coefficient; a2 to a 10 They represent the coefficients corresponding to the diameter and radius of each curved surface.

[0068] The second concave beam splitter 4 is a meniscus lens, with the concave surface facing the polarization modulating element. The S4-1 surface and the S4-2 surface are rotationally symmetrical spherical surfaces. The curvature radius of the S4-1 surface and the S4-2 surface are both 20.2 mm, the thickness is 1.6 mm, and the material is optical plastic PMMA.

[0069] The polarization modulating element 5 comprises a flat plate element 51 , a reflective polarizer 52 and a quarter wave plate 53 , which are glued together in sequence. The total thickness of the polarization modulating element is 2 mm.

[0070] The optical system has a relay image between the polarization light modulating element and the first plane beam splitter, and the relay image can compress the size of the light on the subsequent optical element, reduce the aperture of the optical element, and reduce the weight of the optical system.

[0071] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and intent of the present invention.

Claims

1. A near-eye display optical system, characterized in that: The invention comprises an image source, a first plane beam splitter, a concave reflector, a second concave beam splitter, and a polarization light modulating element which are sequentially arranged along an optical path. The left-handed circularly polarized light emitted by the image source is folded multiple times by the first plane beam splitter, the concave reflector, the second concave beam splitter, and the polarization light modulating element, and is sequentially converted into right-handed circularly polarized light, left-handed circularly polarized light, S-linearly polarized light, left-handed circularly polarized light, and P-linearly polarized light. Finally, the polarization light modulating element emits P-linearly polarized light to be incident on a human eye. The external scene light passes through the first plane beam splitter, the second concave beam splitter, and the polarization dimming element in sequence before reaching the human eye, thereby realizing the superposition display of the display image and the external scene.

2. A near-eye display optical system according to claim 1, characterized in that: The image source includes an OLED image source, a linear polarizer, and a first quarter wave plate in a superposition order, the natural light emitted by the OLED image source is converted into P polarized light after passing through the linear polarizer, and the P polarized light is converted into a left-handed circularly polarized light beam after passing through the first quarter wave plate; Alternatively, the image source includes an LCD image source and a first quarter wave plate in a superimposed order.

3. A near-eye display optical system according to claim 2, characterized in that: The first plane beam splitter forms an angle of 40° to 50° with the plane where the image source is located, has a thickness between 1 and 5 mm, and is made of optical glass or optical resin; the plane adjacent to the image source is coated with a beam splitter film, and the plane away from the image source is coated with an anti-reflection film, which is used to transmit the light beam and adjust the propagation direction of the light beam.

4. A near-eye display optical system according to claim 3, characterized in that: The concave reflector is coated with a reflective film, the concave surface is a rotationally symmetrical spherical surface or an aspherical surface, the radius of curvature of the concave surface is between 15 mm and 35 mm, and the material is optical glass, aluminum or optical resin; its position is opposite to the image source, and it receives the left-handed circularly polarized light beam transmitted by the first plane beam splitter, reflects the left-handed circularly polarized light beam and converts it into a right-handed circularly polarized light beam, and then it is incident on the first plane beam splitter again.

5. A near-eye display optical system according to claim 4, characterized in that: The second concave beam splitter is arranged in the reflection light path of the first plane beam splitter, and the convex surface adjacent to the first plane beam splitter is coated with a beam splitting film, and the concave surface adjacent to the polarization modulating element is coated with an anti-reflection film, so as to transmit the left-handed circularly polarized light to the polarization modulating element, and then reflect the left-handed circularly polarized light returned by the polarization modulating element into right-handed circularly polarized light.

6. A near-eye display optical system according to claim 5, characterized in that: The second concave beam splitter is a meniscus lens, two surfaces of which are rotationally symmetrical spherical or aspherical surfaces, the concave curvature radius is between 15 mm and 30 mm, the thickness is between 1 and 5 mm, and the material is optical glass or optical resin.

7. A near-eye display optical system according to claim 6, characterized in that: The polarization dimming element includes a second quarter-wave plate, a reflective polarizer, and a flat plate element which are sequentially arranged along the optical path. The second quarter-wave plate converts the incident left-handed circularly polarized light into S-linear polarized light. The S-linear polarized light is reflected by the reflective polarizer and then converted into left-handed circularly polarized light through the second quarter-wave plate. The left-handed circularly polarized light is then reflected by a second concave beam splitter and then converted into right-handed circularly polarized light. The right-handed circularly polarized light is converted into P-linear polarized light through the second quarter-wave plate. The P-linear polarized light is incident on the human eye after passing through the reflective polarizer and the flat plate element.

8. A near-eye display optical system according to claim 7, characterized in that: The second quarter wave plate, the reflective polarizer and the flat plate element in the polarization modulating element are glued and fixedly connected in sequence, and the total thickness of the polarization modulating element is 1-5 mm.

9. A near-eye display optical system according to claim 8, characterized in that: The distance between the exit pupil of the near-eye display optical system and the polarization dimming element along the visual horizon is not less than 6 mm.

10. A near-eye display optical system according to claim 9, characterized in that: The distances between the image source, the first plane beam splitter, the concave reflector, the second concave beam splitter, and the polarization modulating element are set as follows: The distance between the image source and the first plane beam splitter along the optical axis is between 8 mm and 10 mm, and the closest distance between the two is greater than 1 mm; The distance between the first plane beam splitter and the concave reflector along the optical axis is between 13.5 mm and 16.5 mm, and the closest distance between the two is greater than 1 mm; The distance between the first plane beam splitter and the second concave beam splitter along the optical axis is between 8 mm and 12 mm, and the closest distance between the two is greater than 1 mm; The closest distance between the concave reflector and the second concave beam splitter is greater than 1 mm; The distance between the second concave beam splitter and the polarization modulating element along the optical axis is between 3 mm and 5 mm, and the shortest distance between the two is greater than 1 mm.

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