Eyepieces for near-eye display devices

Abstract

The present invention discloses an eyepiece for a near-eye display device, relates to the field of optical technology, and is used to solve the problem of serious stray light in existing near-eye display devices. The near-eye display device includes an image source and an eyepiece, and the eyepiece includes a reflective element and at least one lens, so that the outgoing light of the image source is incident on the reflective element, reflected by the reflective element to the at least one lens, and the reflected light passes through the at least one lens in sequence and then exits. The at least one lens includes a preset lens adjacent to the reflective element, and a first film layer is provided on a side of the preset lens close to the reflective element, so that the reflectivity of light with an angle greater than or equal to the first preset angle is less than the first preset value when it passes through the first film layer and enters the preset lens. In this way, the reflection of these light rays with larger angles on the preset lens can be reduced, and the situation in which light rays with larger angles are reflected by the preset lens and then exit through the at least one lens can be reduced, thereby reducing stray light.

Description

Technical Field

[0001] The present invention relates to the field of optical technology, and in particular to an eyepiece used in a near-eye display device. Background Art

[0002] Augmented Reality (AR) technology uses optoelectronic display technology, interactive technology, multiple sensor technologies, computer graphics and multimedia technology to integrate a computer-generated virtual environment with the real environment around the user, so that the user can be convinced from a sensory effect that the virtual environment is an integral part of the real environment around him.

[0003] A near-eye display device is a display device based on augmented reality technology. Its structure includes an image source, an eyepiece, and a display screen. The light emitted by the image source passes through the eyepiece and then enters the display screen for display. However, existing near-eye display devices have the following problems: Figure 1 The figure shows a schematic diagram of the arrangement of the image source and eyepiece of an existing near-eye display device. In this scheme, the light emitted by the image source 5 directly enters the coaxially arranged eyepiece 6, but the image source 5 is arranged perpendicular to the temples 7 of the near-eye display device, so that the width of the temples 7 of the near-eye display device is limited by the size of the image source 5, making the temples 7 of the near-eye display device relatively wide, which is not conducive to miniaturization.

[0004] In order to reduce the volume, one solution is to arrange the image source 5 parallel to the temples 7 of the near-eye display device, while the eyepiece 6 is arranged parallel to the temples 7 of the near-eye display device. Therefore, it is necessary to use optical elements to deflect the light emitted by the image source 5 and enter the eyepiece 6. However, the use of optical elements makes the stray light generated more serious. Summary of the Invention

[0005] An object of the present invention is to provide an eyepiece for use in a near-eye display device, capable of reducing stray light.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] An eyepiece for a near-eye display device, the near-eye display device comprising an image source and the eyepiece, the eyepiece comprising a reflective element and at least one lens arranged in sequence, such that light emitted from the image source is incident on the reflective element, reflected by the reflective element to the at least one lens, and the reflected light sequentially passes through the at least one lens before being emitted;

[0008] The at least one lens includes a preset lens adjacent to the reflective element, and a first film layer is provided on a side of the preset lens close to the reflective element, so that the reflectivity of light with an angle greater than or equal to the first preset angle is less than a first preset value when passing through the first film layer and incident on the preset lens.

[0009] In some embodiments, the first film layer makes the reflectivity of the reflected light with an angle less than or equal to a second preset angle less than a second preset value when the reflected light passes through the first film layer and is incident on the preset lens.

[0010] In some embodiments, the reflective element includes a reflective surface and a first surface, and when the outgoing light of the image source is incident on the reflective element, it is reflected by the reflective surface, and the reflected light passes through the first surface and is incident on the at least one lens;

[0011] A second film layer is provided on the first surface, and the second film layer makes the reflectivity of light with an angle greater than or equal to the first preset angle less than a third preset value when the light passes through the second film layer and is emitted from the first surface.

[0012] In some embodiments, the second film layer ensures that the reflectivity of the reflected light with an angle less than or equal to the second preset angle is less than a fourth preset value when the reflected light passes through the second film layer and is emitted from the first surface.

[0013] In some embodiments, the first surface is bonded to the preset lens, and an adhesive layer is provided between the first surface and a side surface of the preset lens close to the reflective element.

[0014] In some embodiments, the first film layer includes at least two sub-film layers with different refractive indices stacked together, the at least two sub-film layers with different refractive indices include a first high-refractive-index sub-film layer and a first low-refractive-index sub-film layer, the first high-refractive-index sub-film layer is the sub-film layer with the highest refractive index among the at least two sub-film layers with different refractive indices, the first low-refractive-index sub-film layer is the sub-film layer with the lowest refractive index among the at least two sub-film layers with different refractive indices, the refractive index of the first high-refractive-index sub-film layer is between the refractive index of the preset lens and the refractive index of the medium on the side of the first film layer away from the preset lens, and the refractive index of the first low-refractive-index sub-film layer is less than the refractive index of the preset lens and less than the refractive index of the medium on the side of the first film layer away from the preset lens;

[0015] Or / and, the second film layer includes at least two sub-film layers with different refractive indices arranged in a stacked manner, and the at least two sub-film layers with different refractive indices include a second high refractive index sub-film layer and a second low refractive index sub-film layer, the second high refractive index sub-film layer is the sub-film layer with the highest refractive index among the at least two sub-film layers with different refractive indices, and the second low refractive index sub-film layer is the sub-film layer with the lowest refractive index among the at least two sub-film layers with different refractive indices, the refractive index of the second high refractive index sub-film layer is between the refractive index of the reflective element and the refractive index of the medium on the side of the second film layer away from the reflective element, and the refractive index of the second low refractive index sub-film layer is smaller than the refractive index of the reflective element and smaller than the refractive index of the medium on the side of the second film layer away from the reflective element.

[0016] In some embodiments, the at least one lens includes a first lens, a second lens, and a third lens arranged in sequence from a side far away from the reflective element to a side close to the reflective element, and the third lens is the preset lens. If the light passes through the first lens, the second lens, and the third lens in sequence, the light gradually converges.

[0017] In some embodiments, the following conditional formula is satisfied:

[0018] 1 <f1 / f<1.5,-1.5<f2 / f<-1,0.5<f3 / f<1;

[0019] Wherein, f1 represents the focal length of the first lens, f2 represents the focal length of the second lens, f3 represents the focal length of the third lens, and f represents the focal length of the eyepiece.

[0020] In some embodiments, the object-side surface and image-side surface of the first lens are concave and convex, respectively; the object-side surface and image-side surface of the second lens are concave and convex, respectively; the object-side surface and image-side surface of the third lens are plane and convex, respectively; the object-side surface and image-side surface of the first lens are both even-order aspherical surfaces; the image-side surface of the third lens is an even-order aspherical surface; and the second lens is a spherical lens.

[0021] In some embodiments, the following conditional formula is satisfied: 1<(dn1 / dT) / (dn2 / dT)<1.5, 2<(dn3 / dT) / (dn2 / dT)<2.5;

[0022] Wherein, n1 represents the refractive index of the first lens, n2 represents the refractive index of the second lens, n3 represents the refractive index of the third lens, and T represents temperature.

[0023] As can be seen from the above technical solution, the eyepiece provided by the present invention is applied to a near-eye display device, wherein the near-eye display device includes an image source and an eyepiece, wherein the eyepiece includes a reflective element and at least one lens arranged in sequence, so that light emitted from the image source is incident on the reflective element, reflected by the reflective element to the at least one lens, and the reflected light sequentially passes through the at least one lens before being emitted. The at least one lens includes a preset lens adjacent to the reflective element, and a first film layer is provided on a side of the preset lens adjacent to the reflective element, so that the reflectivity of light at an angle greater than or equal to a first preset angle when passing through the first film layer and incident on the preset lens is less than a first preset value.

[0024] The beneficial effect of the present invention is that a first film layer is provided on the side of the preset lens close to the reflective element, so that the reflectivity of light with an angle greater than or equal to the first preset angle is less than the first preset value when it passes through the first film layer and is incident on the preset lens, and the reflectivity of light with an angle greater than or equal to the first preset angle is smaller when it passes through the first film layer and is incident on the preset lens, thereby reducing the reflection of these light with larger angles on the preset lens, and reducing the situation where these light with larger angles are reflected by the preset lens and then emitted through the at least one lens, thereby reducing stray light. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 A schematic diagram of the arrangement of an image source and an eyepiece of an existing near-eye display device;

[0027] Figure 2 A top view of an eyepiece and image source arrangement provided in accordance with an embodiment of the present invention;

[0028] Figure 3 for Figure 2 Side view of the eyepiece and image source arrangement shown;

[0029] Figure 4 is a reflectivity curve of the first film layer according to an embodiment of the present invention;

[0030] Figure 5 is a reflectivity curve of the second film layer according to an embodiment of the present invention;

[0031] Figure 6 A schematic diagram showing an eyepiece lens, a reflective element, and an image source disposed in a housing according to an embodiment of the present invention;

[0032] Figure 7 An MTF diagram of an eyepiece provided in one embodiment of the present invention;

[0033] Figure 8 A spot diagram of an eyepiece provided in accordance with an embodiment of the present invention;

[0034] Figure 9 Field curvature and distortion diagrams for the full field of view and full wavelength range of the eyepiece provided by one embodiment of the present invention;

[0035] Figure 10 Axial chromatic aberration curve diagram of an eyepiece provided by an embodiment of the present invention;

[0036] Figure 11-1 This is an MTF diagram of the eyepiece provided by one embodiment of the present invention at -40°C;

[0037] Figure 11-2 This is an MTF diagram of the eyepiece at 20°C provided by an embodiment of the present invention;

[0038] Figure 11-3 This is an MTF diagram of the eyepiece provided by one embodiment of the present invention at 70°C.

[0039] The reference numerals in the drawings of the specification include:

[0040] 1-first lens, 2-second lens, 3-third lens, 4-reflective element, 5-image source, 6-eyepiece, 7-temple, 8-housing, 11-object side surface of the first lens, 12-image side surface of the first lens, 21-object side surface of the second lens, 22-image side surface of the second lens, 31-object side surface of the third lens, 32-image side surface of the third lens. DETAILED DESCRIPTION

[0041] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0042] This embodiment provides an eyepiece for use in a near-eye display device. The near-eye display device includes an image source and the eyepiece. The eyepiece includes a reflective element and at least one lens arranged in sequence, so that light emitted from the image source is incident on the reflective element, reflected by the reflective element to the at least one lens, and the reflected light sequentially passes through the at least one lens before being emitted.

[0043] The at least one lens includes a preset lens adjacent to the reflective element, and a first film layer is provided on a side of the preset lens close to the reflective element, so that the reflectivity of light with an angle greater than or equal to the first preset angle is less than a first preset value when passing through the first film layer and incident on the preset lens.

[0044] The outgoing light of the image source is incident on the reflective element, and is reflected by the reflective element to the at least one lens. The reflected light is incident on a preset lens adjacent to the reflective element, and further passes through the at least one lens before being emitted.

[0045] The angle of a ray refers to the angle between the ray and the optical axis of the eyepiece optical system. A ray incident on the preset lens at an angle greater than or equal to a first preset angle can be considered as a ray incident on the preset lens at an angle greater than or equal to the first preset angle with the optical axis of the preset lens.

[0046] For existing near-eye display devices, optical elements are used to bend the light emitted by the image source 5 and then enter the eyepiece 6. Since the light undergoes Fresnel reflection on the optical element or on the lens of the eyepiece 6, light with a larger angle will be generated. After these larger-angle light rays are reflected multiple times by the optical element or lens, they may enter the display screen through the eyepiece, forming stray light and affecting the display quality.

[0047] In the eyepiece of this embodiment, a first film layer is provided on the side of the preset lens close to the reflective element, so that the reflectivity of light with an angle greater than or equal to the first preset angle is less than the first preset value when it passes through the first film layer and is incident on the preset lens. The reflectivity of light with an angle greater than or equal to the first preset angle is smaller when it passes through the first film layer and is incident on the preset lens, thereby reducing the reflection of these light rays with larger angles on the preset lens, and reducing the situation where these light rays with larger angles are reflected by the preset lens and are emitted through at least one lens, thereby reducing stray light.

[0048] The first film layer reduces the difference in refractive index between the preset lens and the medium on one side of it. That is, the first film layer creates a gradual transition in refractive index between the preset lens and the medium on one side of the preset lens, so that the reflectivity of light with an angle greater than or equal to a first preset angle passing through the first film layer and the side of the preset lens is less than a first preset value. Therefore, the provision of the first film layer can reduce the reflectivity of light incident on the preset lens from the side of the preset lens near the reflective element at an angle greater than or equal to the first preset angle to less than the first preset value. It can also reduce the reflectivity of light emitted from the preset lens to the side near the reflective element at an angle greater than or equal to the first preset angle to less than the first preset value, thereby reducing stray light.

[0049] If the side of the preset lens close to the reflective element is air, the first film layer reduces the refractive index difference between the preset lens and the air, so that the reflectivity of light with an angle greater than or equal to the first preset angle is less than the first preset value when passing through the first film layer and the side of the preset lens.

[0050] In this embodiment, the first preset angle is not limited. In practical applications, it can be determined based on the angle of stray light that affects the imaging effect after the outgoing light from the image source passes through the reflective element and the lens. In some embodiments, the first preset angle can range from 75° to 85°.

[0051] In some embodiments, the first film layer causes reflected light rays with an angle less than or equal to a second preset angle to have a reflectivity less than a second preset value when incident on the preset lens through the first film layer. Light rays incident on the preset lens with an angle less than or equal to the second preset angle can be considered as light rays incident on the preset lens with an angle less than or equal to the second preset angle with the optical axis of the preset lens. The first film layer causes reflected light rays with an angle less than or equal to the second preset angle to have a reflectivity less than the second preset value when incident on the preset lens through the first film layer. This can reduce the reflectivity of reflected light rays with an angle less than or equal to the second preset angle when incident on the preset lens through the first film layer, allowing more reflected light rays with an angle less than or equal to the second preset angle to penetrate the preset lens and further pass through the at least one lens before exiting. In this way, when reflected light rays from the reflective element enter the at least one lens, while ensuring that as much light rays with an angle less than or equal to the second preset angle as possible enter the at least one lens, reflection of light rays with an angle greater than or equal to the first preset angle is reduced, thereby reducing stray light.

[0052] In this embodiment, the second preset angle is not limited and, in practical applications, can be set based on the field of view of the optical system formed by the at least one lens. The second preset angle can correspond to the field of view of the optical system formed by the at least one lens. In some embodiments, the second preset angle can range from 30° to 40°.

[0053] In some embodiments, the first preset value and / or the second preset value can be adjusted by optically designing the first film layer. For example, the first preset value can be 1.5% and the second preset value can be 1%. As long as the reflectivity of the first film layer for light at corresponding angles meets the requirements, there is no specific limit on the size of the reflective element, and the effect of reducing or even eliminating stray light can be achieved, thereby further reducing the volume of the entire eyepiece.

[0054] In some embodiments, a reflective element includes a reflective surface and a first surface. When light emitted from the image source is incident on the reflective element, it is reflected by the reflective surface. The reflected light then passes through the first surface and is incident on the at least one lens. A second film is disposed on the first surface. The second film ensures that light with an angle greater than or equal to the first preset angle has a reflectivity less than a third preset value when it exits the first surface through the second film. Light incident on the first surface at an angle greater than or equal to the first preset angle can be considered light incident on the first surface at an angle greater than or equal to the first preset angle with the optical axis of the first surface. By disposing the second film on the first surface of the reflective element, the second film ensures that light with an angle greater than or equal to the first preset angle has a reflectivity less than the third preset value when it exits the first surface through the second film. Light with an angle greater than or equal to the first preset angle has a reflectivity less than the third preset value when it exits the first surface through the second film. This reduces the reflectivity of light with an angle greater than or equal to the first preset angle when it exits the first surface through the second film, thereby reducing the reflection of these light with larger angles when they pass through the first surface of the reflective element. This reduces the incidence of these light with larger angles reflected by the first surface of the reflective element and the occurrence of these light with larger angles exiting through the at least one lens, thereby reducing stray light.

[0055] The second film layer reduces the difference in refractive index between the reflective element and the medium on one side of the reflective element. That is, the second film layer gradually transitions the refractive index between the reflective element and the medium on one side of the reflective element, so that the reflectivity of light with an angle greater than or equal to the first preset angle passing through the first surface is less than a third preset value. Therefore, the provision of the second film layer can reduce the reflectivity of light with an angle greater than or equal to the first preset angle incident on the first surface from the reflective element to be less than the third preset value when it is emitted through the first surface. It can also reduce the reflectivity of light with an angle greater than or equal to the first preset angle incident on the first surface of the reflective element from the side of the reflective element near the preset lens to be less than the third preset value, thereby reducing stray light. If the side of the reflective element near the preset lens is air, the second film layer reduces the difference in refractive index between the reflective element and the air, so that the reflectivity of light with an angle greater than or equal to the first preset angle incident on the first surface of the reflective element is less than the third preset value.

[0056] In some embodiments, the second film layer causes reflected light rays with angles less than or equal to the second preset angle to have a reflectivity less than a fourth preset value when emitted from the first surface after passing through the second film layer. Light rays incident on the first surface at angles less than or equal to the second preset angle can be considered light rays incident on the first surface at an angle less than or equal to the second preset angle with the optical axis of the first surface. The second film layer causes reflected light rays with angles less than or equal to the second preset angle to have a reflectivity less than a fourth preset value when emitted from the second surface. This can reduce the reflectivity of reflected light rays with angles less than or equal to the second preset angle when emitted from the first surface, allowing more reflected light rays with angles less than or equal to the second preset angle to be transmitted from the first surface and further pass through the at least one lens. In this way, when the image source's emitted light rays are reflected by the reflective element and then incident on the lens, while maximizing the amount of reflected light rays with angles less than or equal to the second preset angle when emitted from the first surface of the reflective element are transmitted through the first surface and further enter the lens, light rays incident on the first surface at angles greater than or equal to the first preset angle are less reflected on the first surface, thereby reducing stray light.

[0057] In some embodiments, the third preset value and / or the fourth preset value may be adjusted by optically designing the second film layer. For example, the third preset value may be 5% and the fourth preset value may be 1.5%.

[0058] In some embodiments, the first surface of the reflective element can be arranged to fit the preset lens, so that the structure is compact, a part of the space in the length direction of the eyepiece can be saved, and the conflict between stray light and volume can be solved. In some embodiments, an adhesive layer is provided between the first surface of the reflective element and a side surface of the preset lens close to the reflective element, and the adhesive layer is used to bond the reflective element and the preset lens. In this embodiment, the first film layer is located between the side surface of the preset lens and the adhesive layer. The first film layer reduces the difference in refractive index between the preset lens and the adhesive layer, so that the reflectivity of light with an angle greater than or equal to the first preset angle passing through the first film layer and the side surface of the preset lens is less than the first preset value. The second film layer is located between the first surface of the reflective element and the adhesive layer. The second film layer reduces the difference in refractive index between the reflective element and the adhesive layer, so that the reflectivity of light with an angle greater than or equal to the first preset angle passing through the first surface of the reflective element is less than a third preset value.

[0059] In some embodiments, the reflective element may be a prism, including but not limited to a triangular prism, a quadrangular prism, a pentagonal prism, or a polygonal prism. One surface of the prism may be used as a reflective surface, and the other surface may be used as a first surface to be bonded to a preset lens. For example, reference may be made to Figure 2 , Figure 2 A top view of an eyepiece and image source arrangement provided in one embodiment is provided. Figure 3 for Figure 2 A side view of the eyepiece and image source arrangement is shown. As shown, the eyepiece includes a first lens 1, a second lens 2, a third lens 3, and a reflective element 4. Light emitted from an image source 5 is incident on the reflective element 4, reflected by the reflective element 4 to the third lens 3. The reflected light then passes through the third lens 3, the second lens 2, and the first lens 1 in sequence. One surface, or the first surface, of the reflective element 4 is bonded to the side of the third lens 3 closest to the reflective element 4. A first film layer is disposed on the side of the third lens 3 closest to the reflective element 4, and a second film layer is disposed on the first surface of the reflective element 4. The third lens 3 and the reflective element 4 are bonded together by an adhesive layer, which is located between the first and second film layers. Figure 3 In the eyepiece shown, the reflective element 4 is a pentagonal prism. The bonding layer can be glue.

[0060] In some embodiments, the reflective element 4 may be a reflector, and the light emitted by the image source 5 is incident on the mirror surface of the reflector and then reflected into the lens. The reflector may be a plane reflector.

[0061] In some embodiments, the first film layer includes at least two stacked sub-layers having different refractive indices, the at least two sub-layers comprising a first high-refractive-index sub-layer and a first low-refractive-index sub-layer, the first high-refractive-index sub-layer being the sub-layer with the highest refractive index among the at least two sub-layers having different refractive indices, the first low-refractive-index sub-layer being the sub-layer with the lowest refractive index among the at least two sub-layers having different refractive indices, the refractive index of the first high-refractive-index sub-layer being between the refractive index of the preset lens and the refractive index of the medium on the side of the first film layer away from the preset lens, and the refractive index of the first low-refractive-index sub-layer being less than the refractive index of the preset lens and less than the refractive index of the medium on the side of the first film layer away from the preset lens. The reflectivity of the first film layer to light of different angles can be adjusted to meet requirements by adjusting the types of sub-layers of different refractive indices used in the first film layer, the number of layers of each sub-layer, or the thickness of the sub-layers.

[0062] If there is air space between the reflective element 4 and the preset lens, the refractive index of the first high-refractive-index sub-layer is between the refractive index of the preset lens and the refractive index of air, and the refractive index of the first low-refractive-index sub-layer is less than the refractive index of the preset lens and less than the refractive index of air. If the reflective element 4 and the preset lens are bonded together via an adhesive layer, the refractive index of the first high-refractive-index sub-layer is between the refractive index of the preset lens and the refractive index of the adhesive layer, and the refractive index of the first low-refractive-index sub-layer is less than the refractive index of the preset lens and less than the refractive index of the adhesive layer.

[0063] In some embodiments, the second film layer includes at least two stacked sub-layers having different refractive indices, the at least two sub-layers including a second high-refractive-index sub-layer and a second low-refractive-index sub-layer. The second high-refractive-index sub-layer is the sub-layer having the highest refractive index among the at least two sub-layers having different refractive indices, and the second low-refractive-index sub-layer is the sub-layer having the lowest refractive index among the at least two sub-layers having different refractive indices. The refractive index of the second high-refractive-index sub-layer is between the refractive index of the reflective element 4 and the refractive index of the medium on the side of the second film layer away from the reflective element 4, and the refractive index of the second low-refractive-index sub-layer is less than the refractive index of the reflective element 4 and less than the refractive index of the medium on the side of the second film layer away from the reflective element 4. The reflectivity of the second film layer to light of different angles can be adjusted to meet requirements by adjusting the types of sub-layers having different refractive indices included in the second film layer, the number of sub-layers, or the thickness of the sub-layers.

[0064] If there is air space between the reflective element 4 and the preset lens, the refractive index of the second high-refractive-index sub-layer is between the refractive index of the reflective element 4 and the refractive index of air, and the refractive index of the second low-refractive-index sub-layer is lower than the refractive index of the reflective element 4 and lower than the refractive index of air. If the reflective element 4 and the preset lens are bonded together via an adhesive layer, the refractive index of the second high-refractive-index sub-layer is between the refractive index of the reflective element 4 and the refractive index of the adhesive layer, and the refractive index of the second low-refractive-index sub-layer is lower than the refractive index of the reflective element 4 and lower than the refractive index of the adhesive layer.

[0065] In one specific example, corresponding to Figure 2 and Figure 3 In the eyepiece shown, the refractive index of the third lens 3 is 1.79, and the refractive index of the reflective element 4 is 1.49. The reflective element 4 and the third lens 3 are bonded together by an adhesive layer, and the refractive index of the adhesive layer is 1.51.

[0066] The first film layer includes an aluminum oxide (Al2O3) film layer and a silicon dioxide (SiO2) film layer alternately stacked, with specific data shown in Table 1. It can be seen that the first film layer between the third lens 3 and the bonding layer includes eleven sub-layers.

[0067] Table 1

[0068]

[0069] Please refer to Figure 4 As shown, Figure 4The reflectivity curve for the first film layer of one embodiment is obtained based on the data shown in Table 1, including reflectivity curves for p-polarized light and s-polarized light at angles of 0°, 30°, 70°, and 83°. It can be seen that within the visible light range, the reflectivity for light at angles of 0° and 30° can be controlled below 2%. The reflectivity for light at angles of 70° and 83° is basically below 2.5%, and even below 1.5%.

[0070] Please refer to Figure 5 As shown, Figure 5 Figure 2 shows the reflectivity curves of the second film layer of one embodiment, including the reflectivity curves for p-polarized light and s-polarized light at angles of 60°, 65°, 70°, 75°, 80°, and 85°. It can be seen that within the visible light range, the reflectivity at angles of 75°, 80°, and 85° is below 2%. No special control is applied to the reflectivity at angles of 60°, 65°, and 70°.

[0071] In some embodiments, the reflective element 4 includes a reflective surface and a first surface. When the outgoing light from the image source 5 is incident on the reflective element 4, it is reflected by the reflective surface. The reflected light passes through the first surface and then enters the at least one lens. The first surface is bonded to a side of the preset lens close to the reflective element 4. The first film layer is located between the first surface and the side of the preset lens close to the reflective element 4. The refractive index of the preset lens, the refractive index of the first film layer, and the refractive index of the reflective element 4 are all consistent. Under this setting, when the light passes through the first surface of the reflective element 4 and enters the preset lens, and when the light enters the first surface of the reflective element 4 from the preset lens, the reflectivity of the light at an angle greater than or equal to the first preset angle is small, less than a first preset value, thereby achieving the effect of reducing stray light. In this embodiment, the first film layer can be an adhesive layer used to bond the preset lens to the reflective element 4, that is, the refractive index of the preset lens, the refractive index of the adhesive layer, and the refractive index of the reflective element 4 are all consistent.

[0072] In this embodiment, there is no limitation on the number of lenses or the lens surface shape included in the at least one lens, and in actual applications, it can be set according to application requirements. In some embodiments, the at least one lens includes a first lens 1, a second lens 2, and a third lens 3, which are arranged in sequence from the side away from the reflective element 4 to the side close to the reflective element 4, and the third lens 3 is the preset lens. If the light passes through the first lens 1, the second lens 2, and the third lens 3 in sequence, the light gradually converges, so that the radius of the first lens 1, the radius of the second lens 2, and the radius of the third lens 3 will decrease in sequence, making the entire system into a trapezoidal shape, reducing the system volume.

[0073] In some embodiments, the eyepiece further includes a housing 8, which is provided with a first mounting cavity, a second mounting cavity, a third mounting cavity, a fourth mounting cavity and a fifth mounting cavity. The first mounting cavity is for mounting the first lens 1, the second mounting cavity is for mounting the second lens 2, the third mounting cavity is for mounting the third lens 3, the fourth mounting cavity is for mounting the reflecting element 4, and the fifth mounting cavity is for mounting the image source 5. The respective mounting cavities are connected in sequence. Exemplarily, reference can be made to Figure 6 , Figure 6 FIG. Figure 6 is a schematic diagram of the lens, reflecting element and image source of an eyepiece provided in an embodiment. As shown in the figure, as the radii of the first lens 1, the second lens 2 and the third lens 3 decrease in sequence, the radial dimension of the housing 8 decreases in a stepped form from the left end to the right end.

[0074] In some embodiments, the eyepiece satisfies the following conditional expressions: 1 < f1 / f < 1.5, -1.5 < f2 / f < -1, 0.5 < f3 / f < 1; where f1 represents the focal length of the first lens, f2 represents the focal length of the second lens, f3 represents the focal length of the third lens, and f represents the focal length of the eyepiece. Thus, by reasonably distributing the focal lengths and rationally allocating the focal lengths of each lens, it can be achieved that under a large aperture and a 35° field angle, the angles of light deflection borne by the surfaces of each lens are approximately the same, thereby reducing the tolerance sensitivity of the entire system.

[0075] In some embodiments, the object side surface and the image side surface of the first lens are concave and convex respectively, the object side surface and the image side surface of the second lens are concave and convex respectively, and the object side surface and the image side surface of the third lens are flat and convex respectively. For any one of the lenses, the object side surface refers to the surface of the lens close to the image source 5, and the image side surface refers to the surface of the lens far from the image source 5. Reference can be made to Figure 3 As shown, the object side surface 11 of the first lens is concave, the image side surface 12 is convex, the object side surface 21 of the second lens is concave, the image side surface 22 is convex, the object side surface 31 of the third lens is flat, and the image side surface 32 is convex. The object side surface 31 of the third lens is adhered to a surface of the reflecting element 4.

[0076] The surface shapes of the first lens, the second lens and the third lens are not specifically limited. For convenience of processing or cost reduction, they can be selected as spherical surfaces. For improving image quality and further correcting high-order aberrations, aspherical surfaces can also be selected. In some embodiments, both the object side surface 11 and the image side surface 12 of the first lens are even aspherical surfaces, the image side surface 32 of the third lens is an even aspherical surface, and the second lens is a spherical lens.

[0077] In some embodiments, the eyepiece satisfies the following conditional equation: 1 < (dn1 / dT) / (dn2 / dT) < 1.5, 2 < (dn3 / dT) / (dn2 / dT) < 2.5; where n1 represents the refractive index of the first lens, n2 represents the refractive index of the second lens, n3 represents the refractive index of the third lens, and T represents the temperature. Because eyepieces are used in consumer electronics, temperature variations need to be considered to enrich their use cases. Therefore, an athermal design is required for the eyepiece. Athermalizing the optical system requires accounting for the temperature-dependent refractive index variation (dn / dT) of the lens material, making the system insensitive to thermal variations in the environment. The temperature coefficient of refractive index (dn / dT), which measures the temperature-dependent variation of the refractive index, is a key property of transmissive optical components. In this eyepiece, to balance positive deflection at high temperatures with negative deflection at low temperatures and effectively mitigate the effects of temperature, the temperature coefficients of the refractive indices of the first lens 1, the second lens 2, and the third lens 3 are set to satisfy the above conditional equation.

[0078] In one specific example, combining Figure 3 As shown, the eyepiece includes a first lens 1, a second lens 2, and a third lens 3. The surface parameters of each lens can be shown in Table 2 below.

[0079] Table 2

[0080]

[0081] Among them, the aspheric cone coefficient values ​​and aspheric coefficients of each order of the first lens 1 and the third lens 3 are shown in the following table, among which Table 3 shows the aspheric cone coefficient value and aspheric coefficients of each order of the first lens 1, and Table 4 shows the aspheric cone coefficient value and aspheric coefficients of each order of the third lens 3.

[0082] Table 3

[0083]

[0084] Table 4

[0085]

[0086] The optical performance parameters of the eyepiece with the above structure are shown in Table 5 below.

[0087] Table 5

[0088]

[0089] Note: EFFL refers to effective focal length (EFFL), EPD (Entrance Pupil Distance, EPD) refers to entrance pupil diameter, FOV refers to field of view (FOV), and TTL refers to total track length (TTL).

[0090] As shown in Table 5, this eyepiece achieves a total length of 26mm at a wide 35° field of view, making it compact. Based on the formula tan(field of view / 2) = (image height / 2) / EFFL, this eyepiece satisfies the requirement of 0.6 ≤ (image height / 2) / EFFL ≤ 0.8.

[0091] Figure 7 This is an MTF (Modulation Transfer Function) diagram of an eyepiece provided in an embodiment. The OTF modulus refers to the optical transfer function modulus, which represents the resolution of the eyepiece. The higher the OTF modulus, the better the resolution and the stronger the resolution capability of the eyepiece. The test wavelength is 0.46μm to 0.64μm. Figure 7 It can be seen that the image MTF of the eyepiece within the full field of view at the center of the image is ≥0.4@30lp / mm, and the resolution of the human eye is approximately 0.2@30lp / mm. That is, the OTF modulus value under 30 line pairs is below 0.2, which will be interpreted as unclear by the human eye. The figure shows that the system design meets the resolution requirements of the human eye.

[0092] Figure 8 This is a spot diagram of an eyepiece provided in an embodiment, wherein the RMS radii corresponding to the respective diagrams are 9.572mm, 9.138mm, 9.540mm, 8.827mm, 10.741mm, 11.251mm, 7.094mm, 9.924mm, 7.322mm, 11.114mm, 15.239mm, and 10.853mm, respectively. The GEO radii corresponding to the respective diagrams are 13.660mm, 21.459mm, 22.080mm, 23.993mm, 24.749mm, 23.377mm, 16.638mm, 21.769mm, 15.631mm, 21.926mm, 62.941mm, and 26.835mm, respectively. Figure 8 It can be seen that the root mean square (RMS) of the eyepiece's 100% field of view is less than 15μm, and the image element (pixel size) used by the system is 6 microns, indicating that the system's diffuse spot size is small, almost all within 2.5 pixels, and the imaging quality is good.

[0093] Figure 9 The field curvature and distortion diagrams for the full field of view and full wavelength range of an eyepiece provided in one embodiment are shown. The left diagram shows the field curvature diagram, with a maximum field of view of 8.840 degrees, sagittal field curvature of 0.1196 mm, and meridional field curvature of 0.1720 mm. The right diagram shows the distortion diagram, with a maximum field of view of 8.840 degrees and a maximum distortion of 2.9348%. Figure 9 It can be seen that the distortion curve of the eyepiece has an almost monotonic trend and no obvious mutations. The image will not be significantly deformed due to different field angles. The maximum optical distortion is less than 3%, and the shape of the distortion curve is controlled to prevent beard distortion.

[0094] Figure 10 The axial chromatic aberration curve of the eyepiece provided in one embodiment has a maximum field of view of 8.8398 degrees and a wavelength of 0.54 μm. Figure 10 It can be seen that the axial chromatic aberration of the eyepiece is less than 10 μm, which is less than 1.5 pixel sizes, and there will be no obvious color fringing phenomenon.

[0095] Figure 11-1 The MTF diagram of the eyepiece at -40°C provided in one embodiment is as follows: Figure 11-2 The MTF diagram of the eyepiece at 20°C provided in one embodiment is as follows: Figure 11-3 This is an MTF diagram of the eyepiece provided in an embodiment at 70° C. It can be seen that the imaging of the eyepiece is stable at different temperatures.

[0096] The above is a detailed introduction to an eyepiece for a near-eye display device provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core concept. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the present invention.

Claims

1. An eyepiece for a near-eye display device, the near-eye display device comprising an image source and the eyepiece, characterized in that: The eyepiece includes a reflective element and at least one lens arranged in sequence, so that the outgoing light of the image source is incident on the reflective element, is reflected by the reflective element to the at least one lens, and the reflected light sequentially passes through the at least one lens before being emitted; The at least one lens includes a preset lens adjacent to the reflective element, wherein a first film layer is provided on a side of the preset lens close to the reflective element, so that a reflectivity of light with an angle greater than or equal to a first preset angle passing through the first film layer and incident on the preset lens is less than a first preset value, the first film layer includes at least two stacked sub-film layers with different refractive indices, the at least two sub-film layers with different refractive indices include a first high-refractive-index sub-film layer and a first low-refractive-index sub-film layer, the first high-refractive-index sub-film layer is the sub-film layer with the highest refractive index among the at least two sub-film layers with different refractive indices, the first low-refractive-index sub-film layer is the sub-film layer with the lowest refractive index among the at least two sub-film layers with different refractive indices, the refractive index of the first high-refractive-index sub-film layer is between the refractive index of the preset lens and the refractive index of the medium on the side of the first film layer away from the preset lens, and the refractive index of the first low-refractive-index sub-film layer is less than the refractive index of the preset lens and less than the refractive index of the medium on the side of the first film layer away from the preset lens; The reflective element includes a reflective surface and a first surface, and the outgoing light of the image source is reflected by the reflective surface when incident on the reflective element, and the reflected light passes through the first surface and then is incident on the at least one lens; A second film layer is provided on the first surface, wherein the second film layer makes the reflectivity of light with an angle greater than or equal to the first preset angle passing through the second film layer and emitted from the first surface be less than a third preset value, the first surface is bonded to the preset lens, and an adhesive layer is provided between the first surface and a side surface of the preset lens close to the reflective element; the second film layer includes at least two sub-film layers with different refractive indices stacked together, the at least two sub-film layers with different refractive indices include a second high-refractive-index sub-film layer and a second low-refractive-index sub-film layer, the second high-refractive-index sub-film layer is the sub-film layer with the highest refractive index among the at least two sub-film layers with different refractive indices, and the second low-refractive-index sub-film layer is the sub-film layer with the lowest refractive index among the at least two sub-film layers with different refractive indices, the refractive index of the second high-refractive-index sub-film layer is between the refractive index of the reflective element and the refractive index of the adhesive layer, and the refractive index of the second low-refractive-index sub-film layer is lower than the refractive index of the reflective element and lower than the refractive index of the adhesive layer; Alternatively, the first surface is bonded to a side of the preset lens close to the reflective element, the first film layer is located between the first surface and the side of the preset lens close to the reflective element, and the refractive index of the preset lens, the refractive index of the first film layer, and the refractive index of the reflective element are all consistent.

2. The eyepiece for a near-eye display device according to claim 1, wherein: The first film layer ensures that the light with an angle less than or equal to a second preset angle among the reflected light has a reflectivity less than a second preset value when it passes through the first film layer and is incident on the preset lens.

3. The eyepiece for a near-eye display device according to claim 1, wherein: The second film layer ensures that the reflectivity of the light with an angle less than or equal to the second preset angle among the reflected light is less than a fourth preset value when the light passes through the second film layer and is emitted from the first surface.

4. The eyepiece for a near-eye display device according to any one of claims 1 to 3, characterized in that: The at least one lens includes a first lens, a second lens, and a third lens, which are arranged in sequence from a side far away from the reflective element to a side close to the reflective element. The third lens is the preset lens. If light passes through the first lens, the second lens, and the third lens in sequence, the light gradually converges.

5. The eyepiece for a near-eye display device according to claim 4, wherein: The following conditions are met: 1 <f1 / f<1.5,-1.5<f2 / f<-1,0.5<f3 / f<1; Wherein, f1 represents the focal length of the first lens, f2 represents the focal length of the second lens, f3 represents the focal length of the third lens, and f represents the focal length of the eyepiece.

6. The eyepiece for a near-eye display device according to claim 4, wherein: The object side surface and image side surface of the first lens are concave and convex respectively, the object side surface and image side surface of the second lens are concave and convex respectively, the object side surface and image side surface of the third lens are flat and convex respectively, the object side surface and image side surface of the first lens are both even-order aspherical surfaces, the image side surface of the third lens is an even-order aspherical surface, and the second lens is a spherical lens.

7. The eyepiece for a near-eye display device according to claim 4, wherein: The following conditions are met: 1<(dn1 / dT) / (dn2 / dT)<1.5, 2<(dn3 / dT) / (dn2 / dT)<2.5; Wherein, n1 represents the refractive index of the first lens, n2 represents the refractive index of the second lens, n3 represents the refractive index of the third lens, and T represents temperature.

Images