Birdbath near-to-eye display module and device

Abstract

The utility model discloses a Birdbath near-to-eye display module and device, the Birdbath near-to-eye display module comprises a plane spectroscope, a front lens group, a beam splitting lens and a first quarter-wave plate, the surface of the plane spectroscope is provided with a polarization beam splitter; the front lens group is arranged on one side, facing an image source, of the plane spectroscope; the light splitting lens is arranged on the side, away from the human eyes, of the plane spectroscope, and a light splitting film is arranged on the surface of the side, away from the human eyes, of the light splitting lens and used for reflecting light reflected by the plane spectroscope to enable the light to be spread towards the plane spectroscope; and the first quarter-wave plate is arranged between the polarizing beam splitter and the beam splitting lens and is used for changing the polarization state of the image light, so that the light reflected by the beam splitting film is emitted to the exit pupil position through the plane beam splitter. According to the Birdbath near-to-eye display module provided by the utility model, the beam splitting lens with certain focal power is additionally arranged in the polarization folding light path, so that the number of lenses at the front end of a screen is reduced, and the Birdbath near-to-eye display module has positive significance in controlling the size and the cost of a product.

Description

Technical Field

[0001] The utility model relates to a Birdbath near-eye display module, and also relates to a Birdbath near-eye display device. Background Art

[0002] At present, head-mounted display devices are becoming increasingly popular. People can achieve an immersive experience by wearing virtual reality (VR) or augmented reality glasses (AR). Virtual reality and augmented reality near-eye displays have changed the way of human-computer interaction, bringing new possibilities for the convenience of production, life and entertainment consumption. A thin and light form factor and a large field of view have always been the indicators pursued by near-eye display devices. Using Fresnel lenses, pancake, and birdbath solutions can all reduce the size of near-eye display devices to a certain extent, but it is still a major challenge to provide good resolution while maintaining a large field of view.

[0003] The Birdbath (abbreviation: BB) module includes a planar beam splitter, a curved beam splitter, and a front lens group. A folded optical path is constructed through the planar beam splitter and the curved beam splitter. It is named because its semi-transmissive and semi-reflective spherical mirror is somewhat similar to a birdbath base, and it is generally called a BB module in the industry. As the mainstream product in the C-end movie-watching market, the thin and light nature and high cost performance of BB glasses have always been the focus of consumers' attention and the direction of improvement for current manufacturers. Summary of the Invention

[0004] The technical problem to be solved by the utility model is to provide a Birdbath near-eye display module and device.

[0005] In order to achieve the above technical purpose, the utility model adopts the following technical solutions:

[0006] According to an embodiment of the utility model, a Birdbath near-eye display module is provided, including:

[0007] A planar beam splitter, which is inclined on the optical axis and has a polarization beam splitter on one surface. The polarization beam splitter is used to reflect the first linearly polarized light and transmit the second linearly polarized light, so as to reflect the light provided by the image source in a direction away from the human eye;

[0008] A front lens group, which is arranged on the side of the planar beam splitter facing the image source; the front lens group is equivalent to a positive lens;

[0009] A beam-splitting lens is disposed on the side of the planar beam splitter away from the human eye. The beam-splitting lens is a positive lens. The surface of the beam-splitting lens away from the planar beam splitter is convex and is provided with a beam-splitting film for reflecting the light reflected by the planar beam splitter and making it propagate towards the planar beam splitter.

[0010] A first quarter-wave plate is disposed between the polarization beam splitter and the beam-splitting lens for changing the polarization state of the image light so that the light reflected by the beam-splitting film passes through the planar beam splitter and shoots towards the exit pupil position.

[0011] Preferably, the focal length range of the Birdbath near-eye display module is 19 mm to 22 mm.

[0012] Preferably, the Birdbath near-eye display module further includes: a first polarization module disposed between the front lens group and the image source for converting the image light provided by the image source into first linearly polarized light or first circularly polarized light; the first polarization module at least includes a first polarizer for transmitting the first linearly polarized light and absorbing the second linearly polarized light.

[0013] Preferably, the first polarization module further includes a second quarter-wave plate disposed on the surface of the first polarizer facing the image source side and / or a third quarter-wave plate disposed on the surface of the first polarizer facing the planar beam splitter side.

[0014] Preferably, the Birdbath near-eye display module further includes: a compensation lens disposed on the side of the beam-splitting lens away from the planar beam splitter. The surfaces of the compensation lens and the beam-splitting lens close to each other have the same surface shape and are glued together. The surfaces of the compensation lens and the beam-splitting lens facing away from each other have the same surface shape or form a certain surface shape difference to match a predetermined diopter.

[0015] Preferably, the Birdbath near-eye display module further includes: a second polarization module disposed on the side of the compensation lens away from the planar beam splitter for absorbing the image light passing through the beam-splitting film.

[0016] Preferably, the second polarization module includes a second polarizer and a fourth quarter-wave plate. The fourth quarter-wave plate is disposed between the second polarizer and the compensation lens; the second polarizer is used for absorbing the first linearly polarized light and transmitting the second linearly polarized light.

[0017] Preferably, at least one of the surfaces of the beam-splitting lens and the compensation lens facing away from each other is a plane.

[0018] Preferably, the sum of the central thicknesses of the beam-splitting lens and the compensation lens is less than 5 mm.

[0019] According to an embodiment of the present utility model, a Birdbath near-eye display device is provided, including the above-mentioned Birdbath near-eye display module.

[0020] The Birdbath near-eye display module provided by the present utility model, compared with the traditional BB near-eye display module, by designing the far-eye end curved beam splitter into a beam splitting lens with a certain optical power and adding a lens in the folded optical path constructed by the two beam splitting surfaces, reduces the number of lenses in the front lens group arranged at the front end of the screen, which has a positive significance for both product volume and cost control. The above-mentioned Birdbath near-eye display module can expand the field of view while maintaining a small size and has good image imaging quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic diagram of the optical module provided by the first embodiment of the present utility model;

[0022] Figure 2 is a schematic diagram of the optical module provided by the second embodiment of the present utility model;

[0023] Figure 3 is a schematic diagram of the composition of the first polarization module in the second embodiment;

[0024] Figure 4 is a schematic diagram of the optical module provided by the third embodiment of the present utility model;

[0025] Figure 5 is a schematic diagram of the composition of the first polarization module in the third embodiment;

[0026] Figure 6 is the MTF diagram of the optical module provided by the third embodiment of the present utility model. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts shall fall within the protection scope of the present utility model.

[0028] It should be noted that if there are directional indications (such as up, down, left, right, front, back...) involved in the embodiments of the present utility model, the directional indications are only used to explain the relative position relationship and movement conditions between components in a specific posture (as shown in the drawings). If the specific posture changes, the directional indications will also change accordingly.

[0029] In addition, if there are descriptions such as "first", "second", etc. in the embodiments of the present utility model, the descriptions of "first", "second", etc. are only for descriptive purposes and should not be construed as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present utility model.

[0030] As Figure 1 shown, the Birdbath (abbreviation, BB) near-eye display module provided by the present utility model includes: an image source 10, a first polarization module 20, a front lens group 30, a first quarter-wave plate 42, a planar beam splitter 50 (including a polarization beam splitter 41 disposed on its surface), a beam splitting lens 60, a compensation lens 70, and a second polarization module 80. The above BB near-eye display module can be used in augmented reality devices. When the above BB near-eye display module is used for virtual reality device applications, the compensation lens 70 and the second polarization module 80 can be omitted.

[0031] The image source 10 is used to generate an image to be displayed and can be implemented by an LCD screen, an OLED screen, or a micro OLED screen.

[0032] The first polarization module 20 is located at the front end of the light-emitting surface of the image source 10 and is used to change the light emitted by the image source 10 into first linearly polarized light or first circularly polarized light, ensuring the brightness of the displayed image and reducing light leakage. At the same time, the first polarization module 20 also has the function of eliminating reflected stray light. The first polarization module 20 can be attached to the light-emitting surface of the display screen to reduce aberration and ghost images caused by the existence of an optical gap.

[0033] According to the difference of the image source 10, the first polarization module 20 can include different film layers. The first polarization module 20 at least includes a first polarizer (POL) 22. The first polarizer 22 is an absorption type POL and is used to transmit first linearly polarized light and absorb second linearly polarized light. A quarter-wave plate (QWP) 21 can be disposed on the upper surface of the first polarizer 22 to change the polarization state of the image light and eliminate stray light. A quarter-wave plate (QWP) 23 can be disposed on the lower surface of the first polarizer 22 to eliminate stray light and change the polarization state of the image light. Therefore, the first polarization module 20 can be a single-layer POL, or a combination of QWP and POL, or a QWP-POL-QWP combination. Of course, the first polarization module 20 is not necessarily a functional film layer to be provided, and the setting of the first polarization module 20 is not the focus of improvement of this application.

[0034] The front lens group 30 is used to magnify the display screen image and can be a single lens, a positive-negative cemented lens, or a combination of multiple lenses. The front lens group 30 is equivalent to a positive lens.

[0035] The planar beam splitter 50 is inclined and arranged on the visual axis in front of the human eye, and the normal line of the planar beam splitter 50 intersects with the visual axis. One side surface of the planar beam splitter 50 is provided with a polarization beam splitting film 41, and the polarization beam splitting film 41 is a reflective POL, which is used to reflect the first linearly polarized light and transmit the second linearly polarized light; the planar beam splitter 50 is used to reflect the light provided by the image source 10 in a direction away from the human eye and transmit the light incident from the visual axis direction; specifically, the polarization beam splitting film 41 is used to reflect the light emitted by the display screen through the first polarization module 20 and transmit the light that is reflected and transmitted by the beam splitting lens 60 and then incident on the planar beam splitter 50.

[0036] The first quarter-wave plate 42 is arranged between the polarization beam splitting film 41 and the beam splitting lens 60 and is used to change the polarization state of the image light so that the light reflected by the beam splitting film can pass through the planar beam splitter 50 and shoot towards the exit pupil position. The setting position of the first quarter-wave plate 42 depends on the polarization state of the image light emitted by the image source 10 through the front lens group 30 and incident on the planar beam splitter 50. When the light emitted by the image source through the front lens group 30 and incident on the planar beam splitter 50 is the first linearly polarized light, the first quarter-wave plate 42 is only arranged on the optical path between the planar beam splitter 50 and the beam splitting lens 60 and can be arranged between the planar beam splitter 50 and the beam splitting lens 60 or on the surface of the beam splitting lens 60. When the light emitted by the image source 10 through the front lens group 30 and incident on the planar beam splitter 50 is the first circularly polarized light, the first quarter-wave plate 42 is arranged on the surface of the planar beam splitter 50, on the side of the polarization beam splitting film 41 facing the image source, and is used to change the polarization state of the light incident on the polarization beam splitting film 41 for the first time and change the polarization state of the light between the planar beam splitter 50 and the beam splitting lens 60.

[0037] The beam splitting lens 60 is arranged on the side of the planar beam splitter 50 away from the human eye and is located at the far-eye end. The beam splitting lens 60 is a lens with different surface profiles on both sides and has a focal power for the perspective light. The side surface 602 of the beam splitting lens 60 away from the planar beam splitter 50 is a convex surface (concave towards the human eye) and is provided with a beam splitting film, which is used to reflect the light from the planar beam splitter 50 and transmit the external ambient light. The side surface of the beam splitting lens 60 facing the planar beam splitter 102 can be a concave surface, a planar surface, or a convex surface. The beam splitting lens 60 is a positive lens. The focal length of the beam splitting lens 60 can be greater than or less than the focal length of the front lens group 30.

[0038] In an augmented reality application, in order to satisfy the transmission of ambient light, a compensation lens 70 is disposed on the side of the beam splitting lens 60 away from the planar beam splitter 50 to eliminate the aberration generated when the beam splitting lens 60 transmits the external ambient light. The beam splitting lens 60 and the compensation lens 70 can use the same material to keep the refractive index and Abbe number consistent. The inner surface of the compensation lens 70 close to the human eye side is consistent with the beam splitting surface profile of the beam splitting lens 60 and is glued. The surface of the compensation lens 106 away from the beam splitting lens 105 is a plane or a convex surface, preferably a spherical or aspherical surface profile. The surface profiles of the two surfaces of the beam splitting lens 60 and the compensation lens 70 facing away from each other are consistent, so that the transmitted ambient light has zero diopter, or there is a surface profile difference between the two surfaces of the beam splitting lens 60 and the compensation lens 70 facing away from each other to match the diopter of the transmitted ambient light with that of the user. Preferably, at least one of the outer surfaces of the beam splitting lens 60 and the compensation lens 70 is a plane. For example, the surface of the compensation lens 70 away from the human eye side is selected to be a plane to maintain the flat appearance of the optical module and simplify the film pasting process. In order to maintain the thin and light characteristics in the optical axis direction of the optical module, the sum of the central thicknesses of the beam splitting lens 60 and the compensation lens 70 is less than 5 mm.

[0039] A second polarization module 80 is disposed on the side of the compensation lens 70 away from the human eye to eliminate the image light transmitted to the outside through the beam splitting lens 60, that is, to prevent external light leakage; at the same time, the polarization state of the external ambient light is selected to allow the second linearly polarized light to enter the optical module. The second polarization module 80 can be attached to the surface of the compensation lens 70 away from the human eye side to reduce the aberration and ghost images caused by the existence of the optical gap. The second polarization module 80 includes a second polarizer 82 and a fourth quarter-wave plate 81. The fourth quarter-wave plate 81 is disposed between the compensation lens 70 and the second polarizer 82. The fast axis directions of the fourth quarter-wave plate 81 and the first quarter-wave plate 42 are the same. The second polarizer 82 is an absorption type POL for absorbing the first linearly polarized light and transmitting the second linearly polarized light. The transmission direction of the second polarizer 82 is the same as the polarization transmission direction of the polarization beam splitter 41.

[0040] For the above BB near-eye display module, the preferred value of the total focal length is 19 mm to 22 mm. Compared with the traditional BB near-eye display module, in this Birdbath near-eye display module, by designing the far-eye-end curved beam splitter into a beam splitting lens with a certain optical power, it is equivalent to setting two lenses in the folded optical path formed by the two beam splitting surfaces, reducing the focal length design pressure of the front lens group, thereby reducing the number of lenses in the front lens group disposed at the front end of the screen. And, by setting the beam splitting lens in the optical axis direction, the space between the two beam splitting surfaces is fully utilized, reducing the overall volume of the near-eye display module.

[0041] In addition, by gluing a compensation lens made of the same material outside the beam-splitting lens, the optical power in the perspective direction is made to be 0, achieving the effect of observing the external environment without distortion. At the same time, a relatively thin size in the perspective direction is maintained, obtaining good imaging quality.

[0042] For people with refractive errors, on the one hand, by replacing the compensation lens with different surface shapes on the non-glued surface, the surface shape difference of the two outer surfaces of the glued lens composed of the compensation lens and the beam-splitting lens is changed to achieve the visual acuity matching of the ambient light. On the other hand, the imaging optical path of the image light can be made to match the visual acuity of the user's eyes by moving the glued lens, thereby realizing the visual acuity adjustment function of the augmented reality near-eye display device. For people with different visual acuities, only by moving the glued lens, the matching effect between the imaging optical path of the image light and the visual acuity of the user's eyes can also be optimized.

[0043] Several specific embodiments will be schematically described below with reference to the accompanying drawings.

[0044] Embodiment 1:

[0045] As Figure 1 shown in the BB near-eye display module, it includes an image source 10, a first polarization module 20, a front lens group 30, a first quarter-wave plate 42, a planar beam splitter 50 (including a polarization beam splitter 41), a beam-splitting lens 60, a compensation lens 70, and a second polarization module 80.

[0046] Among them, the display screen providing the image source 10 is an LCD screen, an OLED screen, or a micro OLED screen; the first polarization module 20 includes a single absorptive POL (the first POL). If the screen is an LCD screen, the transmission axis of the absorptive POL is the same as the polarization direction of the linearly polarized light emitted by the LCD screen; the light transmitted through the absorptive POL is the first linearly polarized light. The substrate of the planar beam splitter 50 is an optical flat; a single reflective POL (polarizing beam splitter) 41 is attached to the side of the planar beam splitter 50 away from the human eye, and is used to reflect the first linearly polarized light and transmit the second linearly polarized light. The transmission axis of this reflective POL 41 is orthogonal to the transmission axis of the POL in the first polarization module 20; a single quarter-wave plate (the first QWP) 42 is attached to the side of the beam splitting lens 50 facing the human eye, and its fast axis direction forms a 45° angle with the transmission axis of the POL 41, and is used to convert linearly polarized light into circularly polarized light. The beam splitting lens 60 and the compensation lens 70 are glued together to form an optical flat, and a beam splitting film is deposited on the glued surface; the second polarization module 80 includes a single quarter-wave plate (the fourth QWP) 81 and an absorptive POL (the second POL) 82. The fast axis direction of its QWP 81 is the same as the fast axis direction of the QWP 42, and the transmission axis direction of the POL 82 is the same as the transmission axis direction of the POL 41, and is orthogonal to the transmission axis direction of the POL in the first polarization module 20, thereby effectively eliminating the light that may leak out of the display device to the outside world.

[0047] For example, the image light emitted by the display screen is converted into s(p)-type linearly polarized light by the first polarization module 20; after the light passing through the front lens group 30 is reflected by the absorptive POL 41 and transmitted by the QWP 42, the s(p)-type linearly polarized light is converted into left (right)-hand circularly polarized light, and then is converted into right (left)-hand circularly polarized light again after being reflected by the glued surface of the beam splitting lens 60 and the compensation lens 70; after passing through the QWP 42 again, it is converted into p(s)-type linearly polarized light, and finally exits to the human eye after passing through the absorptive POL 41 and the planar beam splitter 50. The QWP 81 of the second polarization module 80 converts the left (right)-hand circularly polarized light passing through the beam splitting lens 60 and the compensation lens 70 into s(p)-type linearly polarized light. Since the polarization direction of the light is orthogonal to the transmission axis of the absorptive POL 82, the light is blocked at this time, and the light inside the device cannot pass through the absorptive POL 82 and enter the external environment.

[0048] Embodiment 2:

[0049] As Figure 2 shown in the BB near-eye display module, it includes an image source 10, a first polarization module 20, a front lens group 30, a first quarter-wave plate 42, a planar beam splitter 50 (including a polarizing beam splitter 41), a beam splitting lens 60, a compensation lens 70, and a second polarization module 80.

[0050] In this embodiment, the display screen providing the image source 10 can be an LCD screen, an OLED screen, or a micro OLED screen; the first polarization module 20 is a combination of a QWP (second QWP) 21 and an absorptive POL (first POL) 22. The light emitted by the screen becomes the first linearly polarized light after passing through the second QWP 21 and the absorptive POL 22 of the first polarization module 20. The polarization beam splitter 41, the first quarter-wave plate 42, the planar beam splitter 50, the beam splitting lens 60, the compensation lens 70, and the second polarization module 80 are arranged in the same way as in Embodiment 1.

[0051] On the basis of Embodiment 1, the first polarization module 20 in Embodiment 2 adds a QWP (second QWP) 21 located between the absorptive POL 22 and the image source 10, which can effectively eliminate the stray light incident from the outside and reflected by the display screen. As Figure 3 shown, the external stray light incident from the lower side of the absorptive POL 22 becomes s(p)-type linearly polarized light after passing through the absorptive POL 22, then becomes left (right)-handed circularly polarized light after passing through the second QWP 21, then becomes right (left)-handed circularly polarized light after being reflected by the screen surface, and then becomes linearly polarized light with a polarization direction orthogonal to the transmission axis of the absorptive POL 22 (shown as p-type linearly polarized light in the figure) after passing through the first QWP 21 again, that is, the external stray light is cut off at the absorptive POL 22 and cannot enter the expected optical path subsequently.

[0052] Embodiment 3:

[0053] As Figure 4 shown, the BB near-eye display module includes an image source 10, a first polarization module 20, a front lens group 30, a first quarter-wave plate 42, a planar beam splitter 50 (including a polarization beam splitter 41), a beam splitting lens 60, a compensation lens 70, and a second polarization module 80.

[0054] In this embodiment, the display screen providing the image source 10 can be an LCD screen, an OLED screen, or a micro OLED screen; the first polarization module 20 is a QWP-POL-QWP combination. A second QWP 21 is provided on the surface of the first POL 22 facing the image source 10, and a third QWP 23 is provided on the surface of the first POL 22 facing the front lens group 30. The fast axis directions of the two QWPs 22 and 23 are the same and are at 45° to the light transmission direction of the first POL 22, so that the image light incident on the front lens group 30 is converted into left-handed circularly polarized light; the substrate of the planar beam splitter 50 is an optical flat plate. A QWP (first QWP) 42 and a reflective POL (polarizing beam splitter) 41 are combined into a QWP-POL composite film and provided on the surface of the planar beam splitter 50 to change the polarization state of light. The light transmission axis of the reflective POL 41 and the fast axis of the QWP 42 are at 45°; the beam splitting lens 60 and the compensation lens 70 are glued into an optical flat plate, and a beam splitting film is deposited on the glued surface; the second polarization module 80 is a combination of a QWP (fourth QWP) 81 and an absorptive POL (second POL) 82, and the fast axis direction of the QWP 81 is orthogonal to the light transmission axis direction of the absorptive POL 82 to eliminate the light that may leak out of the display device to the outside.

[0055] As Figure 4 shown, the light emitted from the screen is changed into left (right)-handed circularly polarized light by the second QWP 21, the absorptive POL 22, and the third QWP 23 of the first polarization module 20; the light passing through the front lens group 30 is changed into s (p)-type linearly polarized light by the first QWP 42; it is emitted again in the left (right)-handed polarization state towards the beam splitting lens 60 through the reflective POL 41 and the QWP 42; the left (right)-handed circularly polarized light is reflected by the beam splitting film of the beam splitting lens 60 and changed into right (left)-handed circularly polarized light, and at this time, it is changed into p (s)-type linearly polarized light with the same direction as the light transmission axis of the reflective POL 41 through the QWP 42 and enters the human eye. The light transmitted outward through the beam splitting film of the beam splitting lens 60 is first changed into linearly polarized light by the QWP 81 of the second polarization module 80 and then absorbed by the absorptive POL 82 and cannot enter the external environment.

[0056] Based on Embodiment 2, Embodiment 3 changes the components of the first polarization module 20, and a QWP 23 is added below the absorptive POL 22 of the first polarization module. As Figure 5As shown, when the light emitted by the screen is reflected at the upper surface 301 of the front lens group 30 after passing through the circularly polarized light of the first polarization module 20, the rotation direction of the light changes. When it passes through the third QWP 23 of the first polarization module 20 again, the polarization direction of the linearly polarized light is orthogonal to the transmission axis of the absorption-type POL 22, and this light is blocked. That is, the third QWP 23 effectively reduces the stray light that may be reflected at the upper surface 301 of the front lens group 30.

[0057] In the above embodiment, the front lens group 30 can use a single lens, a positive-negative cemented lens or a lens group, and the front lens group 30 is equivalent to a positive lens.

[0058] Table 1 Design parameters of each optical lens in Embodiment 3

[0059]

[0060] Taking the front lens group 30 of Embodiment 3 as a single lens as an example, Table 1 gives the design parameters of each optical lens. Among them, surface 301 and surface 302 are the surfaces of the front lens group 30 facing the image source and the human eye respectively, surface 601 and surface 602 are the human-eye-side surface and the environment-side surface of the beam splitter lens 60 respectively, surface 701 and surface 702 are the human-eye-side surface and the environment-side surface of the compensating lens 70 respectively. The front lens 30, the beam splitter lens 60 and the compensating lens 70 are all spherical lenses. The focal length of the front lens group 30 of this Birdbath near-eye display module is 65.069 mm, the focal length of the beam splitter lens 60 is 150.457 mm, and the total focal length of the system is 19.71 mm. The field of view angle of the corresponding optical system can reach 50°. When all lens groups adopt spherical surfaces, the MTF of this optical system is as Figure 6 shown. It can be seen that when the spatial frequency is 30 line pairs per millimeter and the field of view angle is 50°, its MTF>0.1, having good resolution.

[0061] In summary, compared with the traditional BB near-eye display module, the Birdbath near-eye display module provided by the present invention reduces the number of lenses in the front end of the screen by designing the far-eye-end curved beam splitter into a beam splitter lens with a certain optical power, which has a positive significance for both product volume and cost control. In addition, the augmented reality display effect can be achieved by cementing a compensating lens of the same material on the side of the beam splitter lens away from the human eye, so that the optical power in the perspective direction is 0, which can achieve the effect of observing the external environment without distortion. At the same time, the thin and light form of the entire optical module is maintained, and good imaging quality is obtained.

[0062] The above has provided a detailed description of a Birdbath near-eye display module and device according to the present utility model. For those of ordinary skill in the art, any obvious changes made to it without departing from the substantial content of the present utility model will constitute an infringement of the patent right of the present utility model and will bear corresponding legal responsibilities.

Claims

1. A Birdbath near-eye display module, characterized in that include: A plane beam splitter, which is tilted on the visual axis and has a polarizing beam splitter on one side surface, wherein the polarizing beam splitter is used to reflect the first linear polarized light and transmit the second linear polarized light, so as to reflect the light provided by the image source in a direction away from the human eye; A front lens group is arranged on the side of the plane beam splitter facing the image source; the front lens group is equivalent to a positive lens; A beam splitter lens is arranged on the side of the plane beam splitter away from the human eye, the beam splitter lens is a positive lens, and the surface of the beam splitter lens on the side away from the plane beam splitter is a convex surface and is provided with a beam splitter film, which is used to reflect the light reflected by the plane beam splitter and make it propagate toward the plane beam splitter; The first quarter wave plate is arranged between the polarization beam splitter and the beam splitter lens, and is used to change the polarization state of the image light so that the light reflected by the beam splitter film passes through the plane beam splitter and is emitted to the exit pupil position.

2. The Birdbath near-eye display module according to claim 1, wherein: The focal length range of the Birdbath near-eye display module is 19 mm to 22 mm.

3. The Birdbath near-eye display module according to claim 1, characterized in that Also includes: A first polarization module, disposed between the front lens group and the image source, for converting the image light provided by the image source into a first linear polarized light or a first circular polarized light; The first polarization module at least includes a first polarizer, which is used to transmit the first linear polarized light and absorb the second linear polarized light.

4. The Birdbath near-eye display module according to claim 3, characterized in that: The first polarization module further includes a second quarter-wave plate disposed on the side of the first polarizer facing the image source and / or a third quarter-wave plate disposed on the side of the first polarizer facing the plane beam splitter.

5. The Birdbath near-eye display module according to claim 1, characterized in that Also includes: The compensation lens is arranged on a side of the beam splitter lens away from the plane beam splitter. The surfaces of the compensation lens and the beam splitter lens that are close to each other have the same surface shape and are glued together. The surfaces of the compensation lens and the beam splitter lens that are away from each other have the same surface shape or have a certain surface shape difference to match the predetermined diopter.

6. The Birdbath near-eye display module according to claim 5, characterized in that Also includes: The second polarization module is arranged on a side of the compensation lens away from the plane beam splitter, and is used for absorbing the image light passing through the beam splitter film.

7. The Birdbath near-eye display module according to claim 6, characterized in that: The second polarization module includes a second polarizer and a fourth quarter-wave plate, wherein the fourth quarter-wave plate is arranged between the second polarizer and the compensation lens; the second polarizer is used for absorbing the first linear polarized light and transmitting the second linear polarized light.

8. The Birdbath near-eye display module according to claim 5, characterized in that: At least one of the surfaces of the beam splitting lens and the compensation lens facing away from each other is a plane.

9. The Birdbath near-eye display module according to claim 5, characterized in that: The sum of the center thicknesses of the beam splitter lens and the compensation lens is less than 5 mm.

10. A Birdbath near-eye display device, comprising the Birdbath near-eye display module according to any one of claims 1 to 9.

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