Near-eye display modules and wearable devices

Abstract

The embodiments of the present application provide a near-eye display module and a wearable device; wherein the near-eye display module includes an imaging lens group, a beam splitter, a first phase retarder, and a polarized reflective element; wherein the first phase retarder is located between the beam splitter and the polarized reflective element; the imaging lens group includes at least one lens, and at least one free-form surface is provided in the imaging lens group, and the absolute value of the difference between the sag along the first direction and the sag along the second direction of the free-form surface is set to <1mm; wherein the first direction is perpendicular to the second direction, and the first direction is the height direction of the free-form surface. The near-eye display module provided by the embodiments of the present application can reduce the astigmatism of the near-eye display module by introducing at least one free-form surface.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of optical imaging technology. More specifically, the embodiments of the present application relate to a near-eye display module and a wearable device. Background Art

[0002] In recent years, virtual reality (VR) technology has been applied in head-mounted display devices, for example, and has developed rapidly. The core component of VR technology is the optical module. The quality of the image displayed by the optical module directly determines the quality of the head-mounted display device. In existing technologies, the astigmatism of the folded optical path is generally greater than 0.2mm. This means that VR display devices cannot guarantee high image clarity at a wide field of view. This is contrary to the current development trend of VR display products, which require high immersion and high image clarity. Summary of the Invention

[0003] The purpose of this application is to provide a new technical solution for a near-eye display module and a wearable device, which can reduce astigmatism and achieve high-definition imaging under the premise of miniaturization of the near-eye display module.

[0004] In a first aspect, the present application provides a near-eye display module. The near-eye display module includes an imaging lens assembly, a beam splitter, a first phase retarder, and a polarizing reflective element; wherein the first phase retarder is located between the beam splitter and the polarizing reflective element;

[0005] The imaging lens group includes at least one lens, and at least one free-form surface is provided in the imaging lens group, and the absolute value of the difference between the sag along the first direction and the sag along the second direction of the free-form surface is set to be less than 1 mm; wherein the first direction is perpendicular to the second direction, and the first direction is the height direction of the free-form surface.

[0006] Optionally, the absolute value of the sag of the free-form surface along the first direction is 0.75 mm, and the absolute value of the sag of the free-form surface along the second direction is 0.52 mm.

[0007] Optionally, the astigmatism of the near-eye display module is less than 0.1 mm.

[0008] Optionally, the imaging lens assembly includes a first lens, a second lens, and a third lens arranged in sequence along the same optical axis; wherein the surface shapes of the first lens, the second lens, and the third lens include free-form surfaces, aspherical surfaces, or planes.

[0009] Optionally, an absolute value of a ratio of a combined focal length of the second lens and the third lens to a focal length of the first lens satisfies ≤0.3.

[0010] Optionally, the focal length of the first lens is for:

[0011] The focal length of the second lens for:

[0012] The focal length of the third lens for:

[0013] Optionally, the beam splitter element is disposed between the second lens and the first lens, and the first phase retarder and the polarization reflection element are sequentially disposed between the second lens and the third lens.

[0014] Optionally, the near-eye display module further includes a display screen, the first lens is located on a side close to the display screen, and the display screen is configured to emit circularly polarized light or natural light;

[0015] When the light emitted by the display screen is natural light, a superimposed sheet is provided on either side of the first lens, which can be used to convert the natural light emitted by the display screen into circularly polarized light;

[0016] The stacked plate includes a second phase retarder, a third phase retarder, and a second polarization element between the second phase retarder and the third phase retarder.

[0017] Optionally, the overlapping sheet is provided on a surface of the first lens away from the display screen;

[0018] The surface of the first lens away from the display screen is an aspherical surface or a flat surface;

[0019] The surface of the first lens close to the display screen is a free-form surface.

[0020] Optionally, the near-eye display module further includes a first polarizing element;

[0021] The beam splitter is disposed on a surface of the second lens close to the display screen, and the first phase retarder is disposed on a surface of the second lens away from the display screen;

[0022] The polarized reflective element and the first polarizing element are stacked and arranged on a surface of the third lens close to the display screen.

[0023] Optionally, the surface of the second lens close to the display screen is a free-form surface or an aspherical surface, and the surface of the second lens away from the display screen is an aspherical surface or a flat surface;

[0024] The surface of the third lens close to the display screen is a free-form surface or an aspherical surface, and the surface of the third lens away from the display screen is a free-form surface.

[0025] Optionally, the focal length of the near-eye display module is 14 mm to 25 mm.

[0026] Optionally, the total optical length TTL of the near-eye display module is: TTL≤25mm.

[0027] In a second aspect, the present application provides a wearable device, comprising:

[0028] a housing; and

[0029] The near-eye display module as described in the first aspect.

[0030] The beneficial effects of this application are:

[0031] According to the near-eye display module provided in the embodiment of the present application, which is a folded optical path structure design, by introducing at least one free-form surface in the folded optical path design and adjusting the specific surface parameters of the introduced free-form surface, the astigmatism of the near-eye display module can be effectively reduced and the imaging quality can be improved; the near-eye display module provided in the embodiment of the present application can ensure high-definition imaging in a small volume.

[0032] Other features and advantages of the present specification will become apparent from the following detailed description of exemplary embodiments of the present specification with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the specification and, together with the description, serve to explain the principles of the specification.

[0034] Figure 1 This is one of the structural schematic diagrams of the near-eye display module provided in an embodiment of the present application;

[0035] Figure 2 A schematic diagram of a near-eye display module provided in an embodiment of the present application in which a superimposed sheet is provided on the surface of the first lens;

[0036] Figure 3 A schematic diagram of a first phase retarder and a first anti-reflection film disposed on the surface of the second lens in the near-eye display module provided in an embodiment of the present application;

[0037] Figure 4 A schematic diagram of a polarizing reflective element and a first polarizing element disposed on the surface of the third lens in the near-eye display module provided in an embodiment of the present application;

[0038] Figure 5 for Figure 1The spot diagram of the near-eye display module is shown;

[0039] Figure 6 for Figure 1 The MTF curve diagram of the near-eye display module shown;

[0040] Figure 7 for Figure 1 The field curvature distortion diagram of the near-eye display module is shown;

[0041] Figure 8 for Figure 1 The vertical axis chromatic aberration diagram of the near-eye display module is shown;

[0042] Figure 9 The second structural diagram of the near-eye display module provided in an embodiment of the present application;

[0043] Figure 10 for Figure 9 The spot diagram of the near-eye display module is shown;

[0044] Figure 11 for Figure 9 The MTF curve diagram of the near-eye display module shown;

[0045] Figure 12 for Figure 9 The field curvature distortion diagram of the near-eye display module is shown;

[0046] Figure 13 for Figure 9 The vertical axis chromatic aberration diagram of the near-eye display module is shown;

[0047] Figure 14 For Figure 1 、 Figure 9 The field curvature distortion diagram of the aspheric optical solution with the same specifications of the near-eye display module is shown;

[0048] Figure 15 Schematic diagram of the sagittal height of the free-form surface in two directions in an embodiment of the present application;

[0049] Figure 16 is a curve showing a change in the sagittal height of the free-form surface in the first direction in the embodiment of the present application;

[0050] Figure 17 is a curve showing a change in the sagittal height of the free-form surface in the second direction in the embodiment of the present application.

[0051] Description of reference numerals:

[0052] 10. First lens; 11. First surface; 12. Second surface; 20. Second lens; 21. Third surface; 22. Fourth surface; 30. Third lens; 31. Fifth surface; 32. Sixth surface; 40. Display screen; 41. Screen protection glass; 50. Beam splitter; 60. First phase retarder; 70. Polarized reflective element; 80. First polarizing element; 90. Overlay; 91. Second anti-reflection film; 92. Second phase retarder; 93. Second polarizing element; 94. Third phase retarder; 100. First anti-reflection film; 01. Human eye. DETAILED DESCRIPTION

[0053] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that unless otherwise specifically stated, the relative arrangements of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application.

[0054] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present disclosure, its application, or uses.

[0055] Techniques and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the techniques and equipment should be considered part of the specification.

[0056] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0057] It should be noted that like reference numerals and letters refer to like items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0058] The near-eye display module and wearable device provided in the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0059] According to one aspect of an embodiment of the present application, a near-eye display module is provided, which can be suitable for application in wearable devices such as head-mounted display devices (HMDs), such as VR head-mounted display devices.

[0060] Among them, the VR head-mounted display device may include, for example, VR smart glasses or VR smart helmets, and the specific form of the wearable device is not limited in the embodiments of the present application.

[0061] The near-eye display module proposed in the embodiment of this application is shown in FIG. Figures 1 to 4The near-eye display module includes an imaging lens group, a beam splitter 50, a first phase retarder 60, and a polarized reflective element 70; wherein the first phase retarder 60 is located between the beam splitter 50 and the polarized reflective element 70; the imaging lens group includes at least one lens, and at least one free-form surface is provided in the imaging lens group, and the absolute value of the difference between the sag height of the free-form surface along the first direction and the sag height along the second direction is set to be less than 1 mm; wherein the first direction is perpendicular to the second direction, and the first direction is the height direction of the free-form surface, see Figure 15 .

[0062] The near-eye display module proposed in the above embodiment of the present application is an optical module based on a folded optical path (pancake). Figures 1 to 4 The beam splitter 50, the first phase retarder 60, and the polarizing reflective element 70 are disposed between the different lenses within the imaging lens assembly to form a folded optical path for the near-eye display module. The first phase retarder 60 is located between the beam splitter 50 and the polarizing reflective element 70.

[0063] In the near-eye display module proposed in the embodiment of the present application, see Figure 1 The number of lenses in the imaging lens group can be flexibly set as needed. For example, the imaging lens group can be provided with only one lens, or two or more lenses. Specifically, Figure 1 As shown in FIG, three lenses are arranged in the imaging lens group.

[0064] Furthermore, at least one lens in the imaging lens assembly is designed to have a free-form surface, so that the entire imaging lens assembly has at least one free-form surface. By introducing at least one free-form surface into the imaging lens assembly, astigmatism of the near-eye display module can be effectively reduced, thereby improving imaging quality.

[0065] See also Figure 14 , in with Figure 1 Under the same specifications as the near-eye display module shown, the aspheric surface solution without free-form surfaces generally has a folded optical path astigmatism greater than 0.2 mm. This significantly larger astigmatism will affect the final image quality.

[0066] The near-eye display film assembly provided in the embodiments of the present application introduces at least one free-form surface into the entire optical path and rationally adjusts the surface parameters of the free-form surface. For example, the absolute value of the difference between the sag along a first direction and the sag along a second direction of the free-form surface is set to less than 1 mm. The first direction is perpendicular to the second direction, and the first direction is the height direction of the free-form surface. This significantly reduces the astigmatism of the near-eye display module, for example, to less than 0.1, which is very beneficial for high-definition imaging.

[0067] The near-eye display module proposed in the embodiments of this application can achieve good imaging quality while maintaining a small footprint and folding the optical path. Due to its small size, the virtual reality display device using this near-eye display module can be small and lightweight, making it more suitable for users and improving wearing comfort.

[0068] The near-eye display module proposed in the embodiment of the present application is a folded optical path structure design. By introducing at least one free-form surface in the folded optical path design and adjusting the specific surface parameters of the introduced free-form surface, the astigmatism of the near-eye display module can be effectively reduced and the imaging quality can be improved. The near-eye display module provided in the embodiment of the present application can ensure high-definition imaging in a small volume.

[0069] The near-eye display module provided in the embodiment of the present application is specifically a folded optical path, which includes, in addition to an imaging lens group, optical elements such as a spectrometer, a phase delay device and a polarization reflection element for forming a folded optical path.

[0070] The above-mentioned optical elements (optical films) can be used to form a folded light path between the various lenses of the imaging lens group, so that the light is folded back therein to extend the propagation path of the light, which is conducive to the final clear imaging and at the same time helps to reduce the volume of the entire near-eye display module.

[0071] In the near-eye display module proposed in the embodiments of the present application, the number of lenses used can be flexibly adjusted according to specific needs. Increasing the number of lenses used in the folded optical path can improve the imaging quality of the near-eye display module, but it also affects the size of the near-eye display module along the optical axis (horizontally), resulting in a larger volume and increased weight of the near-eye display module.

[0072] In the embodiment of the present application, considering the volume, weight, imaging quality and production cost of the entire near-eye display module, three lenses are designed in the optical path. Figure 1 Of course, the near-eye display module provided in the embodiment of the present application is not limited to having three lenses disposed therein, and this is only an example.

[0073] The light splitting element 50 is, for example, a semi-transparent and semi-reflective film.

[0074] The light splitting element 50 can transmit a portion of light and reflect another portion of light.

[0075] It should be noted that the reflectivity and transmittance of the light-splitting element 50 can be flexibly adjusted according to specific needs, and this is not limited in the embodiments of the present application.

[0076] Optionally, the reflectivity of the light splitting element 50 is 47% to 53%.

[0077] The first phase retarder 60 is, for example, a quarter-wave plate. Of course, the first phase retarder 60 can also be configured as other phase retarder plates such as a half-wave plate as needed.

[0078] In the near-eye display module proposed in the embodiment of the present application, the first phase retarder 60 is provided in the folded light path located near the human eye 01 to change the polarization state of light. For example, it is used to convert linearly polarized light into circularly polarized light, or vice versa.

[0079] The polarized reflective element 70 is, for example, a polarized reflective film / sheet.

[0080] The polarized reflective element 70 is a polarized reflector that reflects horizontally polarized light and transmits vertically polarized light, or a polarized reflector that reflects linearly polarized light at any other specific angle and transmits linearly polarized light perpendicular to the angle.

[0081] In the embodiment of the present application, the first phase retarder 60 and the polarizing reflective element 70 cooperate to analyze and transmit light. The polarizing reflective element 70 has a transmission axis, and the angle between the transmission axis of the polarizing reflective element 70 and the fast axis or slow axis of the first phase retarder 60 is, for example, 45°.

[0082] The three optical elements, the beam splitter 50, the first phase retarder 60, and the polarizing reflective element 70, can be arranged flexibly within the imaging lens assembly. They can be arranged, for example, on one side or both sides of the first lens 10 as needed. However, it must be ensured that the first phase retarder 60 is located between the beam splitter 50 and the polarizing reflective element 70.

[0083] The optical path diagram of the near-eye display module of the embodiment of the present application is shown in Figure 1The light propagation path is: if the incident light is circularly polarized light, then after the incident light enters the imaging lens group, the incident light can be reflected in the imaging lens group and finally passes through the third lens 30 close to the surface of the human eye 01 (see Figure 1 The second surface 12) shown in the figure is emitted, and finally a high-definition picture with good picture quality can be presented to the human eye 01 on the left.

[0084] Optionally, see Figure 16 The absolute value of the sag height of the free-form surface along the first direction is 0.75 mm, see Figure 17 The absolute value of the sagittal height of the free-form surface along the second direction is 0.52 mm.

[0085] On this basis, in the near-eye display module provided in the embodiment of the present application, the absolute value of the difference between the sag along the first direction and the sag along the second direction of each free-form surface is <1 mm.

[0086] It should be noted that when the near-eye display module is not limited to having one lens, the near-eye display module may include two or more lenses, and may include two or more free-form surfaces. At this time, the absolute value of the difference between the sum of the sags of the free-form surfaces along the first direction and the sum of the sags along the second direction should also satisfy the requirement of <1mm.

[0087] In some examples of this application, the astigmatism of the near-eye display module is less than 0.1 mm, see Figure 7 shown.

[0088] The near-eye display module proposed in the embodiments of this application introduces at least one free-form surface in the optical path, which can adjust the astigmatism of the near-eye display module. For example, astigmatism can be reduced to less than 0.1mm. When using the near-eye display module, users can observe high-definition images, thereby enhancing their immersive experience.

[0089] Specifically, astigmatism is the difference in imaging between the horizontal and vertical directions, such as Figure 7 As shown, there are two lines on the field curvature diagram, divided into: T line and S line, representing the vertical and horizontal directions respectively. The difference between these two directions is astigmatism. Figure 7 Shown is Figure 1 The astigmatism of the near-eye display module provided shows that the astigmatism of the near-eye display module is less than 0.1mm.

[0090] In some examples of this application, see Figure 1 The imaging lens assembly includes a first lens 10, a second lens 20 and a third lens 30 arranged in sequence along the same optical axis; wherein the surface shapes of the first lens 10, the second lens 20 and the third lens 30 include free-form surfaces, aspherical surfaces or planes.

[0091] See also Figure 1 For example, the imaging lens assembly may include three optical lenses, namely the first lens 10, the second lens 20, and the third lens 30. The second lens 20 is located between the first lens 10 and the third lens 30, and has the largest outer diameter. The three optical lenses can work together to improve imaging quality.

[0092] For example, the surface shapes of the first lens 10, the second lens 20, and the third lens 30 can be designed to each include at least one free-form surface. In this way, by introducing more free-form surfaces into the optical path design, it is more conducive to clear imaging of the near-eye display module and enhances the user's immersion.

[0093] Of course, the first lens 10 , the second lens 20 and the third lens 30 may also adopt other surface shapes such as aspherical or flat surfaces in consideration of the convenience of film application.

[0094] In some examples of the present application, an absolute value of a ratio of a combined focal length of the second lens 20 and the third lens 30 to a focal length of the first lens 10 satisfies ≤0.3.

[0095] See also Figure 1 The near-eye display module proposed in the above example of this application includes a first lens 10, a second lens 20, and a third lens 30; wherein the third lens 30 is located on the side close to the human eye 01, the first lens 10 is located on the light incident side, and the second lens 20 is located between the first lens 10 and the third lens 30. By adjusting the focal length ratio of the two lenses close to the human eye 01 and the single lens far from the human eye 01, good imaging quality can be guaranteed while minimizing the size of the folded optical path.

[0096] Optionally, the focal length of the first lens 10 is for: The focal length of the second lens 20 for: The focal length of the third lens 30 is for:

[0097] In the near-eye display module of the present embodiment, the third lens 30 and the second lens 20 are positioned near the human eye 01, and the polarizing reflective element 70 forming the folded optical path is, for example, positioned between the second lens 20 and the third lens 30. When the combined focal length of the second lens 20 and the third lens 30 is set to positive, the focal powers of the two lenses are also positive. The angle at which incident light is transmitted through the second lens 20 and the third lens 30 and reaches the polarizing reflective element 70 is relatively small, facilitating a large amount of light entering the human eye 01 for imaging.

[0098] In some examples of the present application, the beam splitter 50 is disposed between the second lens 20 and the first lens 10 , and the first phase retarder 60 and the polarization reflection element 70 are sequentially disposed between the second lens 20 and the third lens 30 .

[0099] The beam splitter 50 , the first phase retarder 60 , and the polarization reflective element 70 form a folded optical path between the three lenses, which can extend the light propagation path and improve the imaging quality.

[0100] In some examples of this application, see Figure 1 The near-eye display module also includes a display screen 40. The first lens 10 is located on a side close to the display screen 40. The display screen 40 is configured to emit circularly polarized light or natural light. When the light emitted by the display screen 40 is natural light, a superimposed sheet 90 is provided on either side of the first lens 10, which can be used to convert the natural light emitted by the display screen 40 into circularly polarized light.

[0101] The stacked sheet 90 includes a second phase retarder 92 , a third phase retarder 94 , and a second polarizing element 93 located between the second phase retarder 92 and the third phase retarder 94 .

[0102] The incident light entering the imaging lens assembly should be circularly polarized. When the display screen 40 emits natural light, the natural light must first be polarized. This is done by converting the natural light into circularly polarized light before entering the imaging lens assembly on the left. The light finally exiting the imaging lens assembly enters the human eye 01 for imaging.

[0103] Optionally, the stacking plate 90 includes a second phase retarder 92, a third phase retarder 94, and a second polarizing element 93 between the second phase retarder 92 and the third phase retarder 94. The stacking plate 90 is a device for converting natural light into circularly polarized light.

[0104] The stacked sheet 90 includes, for example, two phase retarders and a polarizing element disposed between the two phase retarders. Figure 2 The display screen 40 emits natural light, which first passes through a phase retarder (for example, the third phase retarder 94) and remains natural light, then passes through the second polarization element 93 and becomes linearly polarized light, and then passes through another phase retarder (for example, the second phase retarder 92) and becomes circularly polarized light.

[0105] In the stacked plate 90, the two phase retarders are, for example, both quarter-wave plates; one of the quarter-wave plates can be used to adjust the polarization state of light, and the other quarter-wave plate is located on the outermost side and can be used to block a portion of the incident light. Specifically, this portion of light is unwanted light in the imaging. If this portion of light is not blocked, it will be reflected back through the light-emitting surface of the display screen 40 and hit the human eye 01, which is not conducive to the final imaging.

[0106] Optionally, see Figure 1 The light emitting surface of the display screen 40 is provided with a screen protection glass 41.

[0107] The light emitted from the display screen 40 is transmitted through the screen protection glass 41 on the surface and then enters the laminated sheet 90 to undergo polarization state conversion.

[0108] Optionally, the overlapping sheet 90 is provided on the surface of the first lens 10 away from the display screen 40; the surface of the first lens 10 away from the display screen 40 is an aspherical surface or a plane; the surface of the first lens 10 close to the display screen 40 is a free-form surface.

[0109] The overlay sheet 90 is, for example, a composite film formed by sandwiching a polarizing film between two quarter-wave plates. In an embodiment of the present application, the overlay sheet 90 is directly attached to the surface of the first lens 10 using, for example, optical adhesive, and the attached surface is designed to be aspherical or flat. This assembly method simplifies production costs and improves product yield.

[0110] In addition, an anti-reflection film may be provided on both surfaces of the first lens 10 .

[0111] Specifically, see Figure 2 The stacked sheet 90 may further include a second anti-reflection film 91 , and the second anti-reflection film 91 is disposed on a side of the second phase retarder 92 away from the second polarizing element 93 .

[0112] Of course, an anti-reflection film may also be provided on the surface (first surface 11 ) of the first lens 10 close to the display screen 40 .

[0113] Anti-reflective film can reduce reflections, lower reflected energy, and improve light efficiency. Anti-reflective film can be applied to optical components through bonding or coating to form interfaces, increasing transmittance and reducing reflectivity, thereby reducing image distortion and allowing users to enjoy clearer image quality and reduce glare.

[0114] In some examples of this application, see Figure 1 、 Figure 3 and Figure 4 , the near-eye display module further includes a first polarizing element 80;

[0115] The spectrometer 50 is disposed on the surface of the second lens 20 close to the display screen 40, and the first phase retarder 60 is disposed on the surface of the second lens 20 away from the display screen 40; the polarizing reflection element 70 and the first polarizing element 80 are stacked and disposed on the surface of the third lens 30 close to the display screen 40.

[0116] Optionally, the surface of the second lens 20 close to the display screen 40 is a free-form surface or an aspherical surface, and the surface of the second lens 20 away from the display screen 40 is an aspherical surface or a flat surface;

[0117] The surface of the third lens 30 close to the display screen 40 is a free-form surface or an aspherical surface, and the surface of the third lens 30 away from the display screen 40 is a free-form surface.

[0118] The introduction of the first polarization element 80 can be used to reduce stray light.

[0119] In the above example, the optical elements constituting the folded optical path are mounted on different lenses.

[0120] For example, the beam splitter 50 and the first phase retarder 60 are disposed on two surfaces of the second lens 20, while the polarizing reflective element 70 and the first polarizing element 80 are disposed on the same surface of the first lens 10. The beam splitter 50, the first phase retarder 60, and the polarizing reflective element 70 are independently disposed. This allows for greater freedom in optical path design and facilitates adjustment of the alignment accuracy of the various optical components.

[0121] Of course, the light splitting element 50, the first phase retarder 60 and the polarized reflection element 70 can be respectively arranged on flat glass and then arranged in the optical path as independent devices, which is not limited in the embodiment of the present application.

[0122] The near-eye display module provided in the above example is Figure 1 , the light propagation is as follows:

[0123] The display screen 40 emits natural light, which is transmitted through the screen protection glass 41, converted into circularly polarized light by the overlapping sheet 90 on the surface of the first lens 10, transmitted through the spectrometer 50 on the surface of the second lens 20, converted into linearly polarized light (P light) by the first phase retarder 60 on the other surface of the second lens 20, reflected by the polarization reflection element 70 on the surface of the third lens 30, converted into circularly polarized light by the first phase retarder 60 of the second lens 20, reflected by the spectrometer 50, converted into linearly polarized light (S light) by the first phase retarder 60, and then transmitted through the third lens 30 and hits the human eye 01.

[0124] In the near-eye display module provided in the embodiment of the present application, the center thickness T1 of the first lens 10 is: 1mm<T1<8mm, and it includes two optical surfaces, see Figure 1 , which are respectively a first surface 11 close to the display screen 40 and a second surface 12 away from the display screen 40.

[0125] Optionally, the first surface 11 and the second surface 12 may be free-form surfaces, aspherical surfaces or planes.

[0126] More preferably, the first surface 11 is configured as a free-form surface.

[0127] The second surface 12 is provided with a laminated sheet 90, such as Figure 2 As shown, the laminated sheet 90 may include a second anti-reflection film 91 , a second phase retarder 92 , a second polarizing element 93 and a third phase retarder 94 , and an anti-reflection film may also be provided on the first surface 11 .

[0128] By providing the stacking sheet 90 on the second surface 12 of the first lens 10, natural light polarization state conversion is achieved. Natural light emitted by the display screen 40 is converted into circularly polarized light, which then enters the folded optical path structure near the human eye 01 for light folding. Ultimately, the light is emitted through the third lens 30 to form a clear image. This improves the display quality of the near-eye display module, resulting in high-quality images. This enhances the user's viewing experience.

[0129] In the near-eye display module provided in the embodiment of the present application, the center thickness T2 of the second lens 20 is in the range of 3mm<T2<8mm, and it includes two optical surfaces, namely a third surface 21 close to the display screen 40 and a fourth surface 22 away from the display screen 40, see Figure 1 .

[0130] Optionally, the third surface 21 and the fourth surface 22 may be free-form surfaces, aspherical surfaces or planes.

[0131] For example, a light splitting element 50 is provided on the third surface 21, and the third surface 21 may be a free-form surface or an aspherical surface. Figure 3 The first phase retarder 60 is provided on the fourth surface 22. The fourth surface 22 can be a plane or an aspheric surface. The plane or aspheric surface design is more conducive to simplifying the film lamination process.

[0132] In addition, see Figure 3 A first anti-reflection film 100 may also be optionally disposed on the fourth surface 22. In this manner, the first anti-reflection film 100 is also disposed on the fourth surface 22 and may be stacked with the first phase retarder 60. Anti-reflection films can reduce reflections, lower reflected energy, and improve light efficiency. Anti-reflection films can be applied to optical components by gluing or coating to form interfaces, increasing transmittance and reducing reflectivity, thereby minimizing image distortion and providing users with clearer image quality, thereby reducing glare.

[0133] In the near-eye display module provided in the embodiment of the present application, the central thickness T3 of the third lens 30 is in the range of 1mm<T3<8mm, and it includes two optical surfaces, see Figure 1 , which are respectively the fifth surface 31 close to the display screen 40 and the sixth surface 32 away from the display screen 40.

[0134] Optionally, both the fifth surface 31 and the sixth surface 32 are free-form surfaces; or, the fifth surface 31 is an aspherical surface, and the sixth surface 32 is a free-form surface.

[0135] See also Figure 4 , the polarized reflection element 70 and the first polarizing element 80 are disposed on the fifth surface 31 .

[0136] Optionally, the focal length of the near-eye display module is 14 mm to 25 mm.

[0137] Optionally, the total optical length TTL of the near-eye display module is: TTL≤25mm.

[0138] The total optical length of the entire near-eye display module is relatively small, so that the lateral size of the near-eye display module is relatively small, while having excellent imaging performance, which can better enhance the user's wearing comfort and visual experience.

[0139] The imaging lens assembly of the near-eye display module of the present embodiment includes a first lens 10, a second lens 20, and a third lens 30. The refractive index n of the first lens 10, the second lens 20, and the third lens 30 is in the range of 1.4 < n < 1.7; and the chromatic aberration coefficient v of the first lens 10, the second lens 20, and the third lens 30 is in the range of 20 < v < 75. By adjusting the refractive index and chromatic aberration coefficient of the three lenses to match them, the imaging quality of the near-eye display module can be improved.

[0140] In a specific example of the present application, the refractive index of the first lens 10 is 1.54, and the Abbe coefficient is 56.3; the refractive index of the second lens 20 is 1.54, and the Abbe coefficient is 56.3; the refractive index of the third lens 30 is 1.54, and the Abbe coefficient is 55.7.

[0141] The near-eye display module provided by the embodiments of the present application is described in detail below through Example 1 and Example 2.

[0142] Example 1

[0143] See also Figures 1 to 4 The near-eye display module includes an imaging lens assembly, a beam splitter 50, a first phase retarder 60, a polarizing reflective element 70, and a first polarizing element 80. The near-eye display module also includes a display screen 40. The imaging lens assembly includes a first lens 10, a second lens 20, and a third lens 30 along the same optical axis. The first lens 10 is located on a side near the display screen 40, and the third lens 30 is located on a side near the human eye 01.

[0144] The incident light emitted by the display screen 40 is natural light. A stacking sheet 90 is provided on the second surface 12 of the first lens 10. The stacking sheet 90 includes a second phase retarder 92, a third phase retarder 94, and a second polarizing element 93 therebetween.

[0145] The beam splitter 50 is disposed on the third surface 21 of the second lens 20 , the first phase retarder 60 is disposed on the fourth surface 22 of the second lens 20 , and the first polarizing element 80 and the polarizing reflective element 70 are stacked and disposed on the fifth surface 31 of the third lens 30 ;

[0146] The first surface 11 of the first lens 10 is a free-form surface, and the second surface 12 of the first lens 10 is an aspheric surface or a flat surface; the third surface 21 of the second lens 20 is a free-form surface, and the fourth surface of the second lens 20 is a flat surface or an aspheric surface; the fifth surface of the third lens 30 is an aspheric surface, and the sixth surface of the third lens 30 is a free-form surface;

[0147] The focal length of the first lens 10 is -55 mm, the focal length of the second lens 20 is 14.8 mm, and the focal length of the third lens 30 is 226 mm;

[0148] The focal length of the near-eye display module is 18.2 mm;

[0149] The total length TTL of the optical system of the near-eye display module is 23.5 mm.

[0150] Tables 1 to 3 show the specific optical parameters of each lens in the near-eye display module provided in this embodiment 1.

[0151] Table 1 Free surface coefficients

[0152]

[0153]

[0154] Table 2 Aspheric coefficients

[0155]

[0156] Table 3 Parameters of each lens

[0157] Material Lens thickness / mm Lens gap / mm The third lens 30 K26R 2.6 0.3 Second lens 20 APEL 6.23 0.38 First lens 10 APEL 6 2.6

[0158] Regarding the near-eye display module provided in the above embodiment 1, its optical performance can be as follows: Figures 5 to 8 As shown: Figure 5 This is a schematic diagram of the point diagram of the near-eye display module. Figure 6 This is the MTF curve of the near-eye display module. Figure 7 This is the field curvature distortion diagram of the near-eye display module. Figure 8 This is the vertical axis chromatic aberration diagram of the near-eye display module.

[0159] The point diagram refers to the formation of a diffuse pattern spread over a certain range when many light rays emitted from one point pass through the near-eye display module. Due to aberration, the intersection of the light rays with the image plane is no longer concentrated at the same point. It can be used to evaluate the imaging quality of the near-eye display module. Figure 5 As shown, the maximum value of the image point in the spot diagram corresponds to the maximum field of view, and the maximum value of the image point in the spot diagram is less than 11 μm.

[0160] The MTF curve is a modulation transfer function graph that represents the imaging clarity of the near-eye display module through the contrast of black and white line pairs. Figure 6 As shown, the MTF is >0.5 at 60lp / mm, and the image is clear.

[0161] The distortion diagram reflects the difference in image plane position when different fields of view form clear images. Figure 7As shown in the figure, the maximum distortion occurs in the first field of view, and the absolute value is less than 35%. The field curvature diagram reflects the difference in the image plane position at different fields of view to form a clear image, see Figure 7 , the maximum field curvature occurs near 1 field of view, and the maximum value is less than 0.2mm.

[0162] Vertical axial chromatic aberration is also called chromatic aberration of magnification. It mainly refers to the difference in the focal position of blue light and red light on the image plane when a complex main light on the object side is transformed into multiple light rays due to the dispersion of the refraction system. Figure 8 As shown in the figure, the maximum color difference value of the near-eye display module is less than 160μm.

[0163] Example 2

[0164] See also Figure 9 The near-eye display module includes an imaging lens assembly, a beam splitter 50, a first phase retarder 60, a polarizing reflective element 70, and a first polarizing element 80. The near-eye display module also includes a display screen 40. The imaging lens assembly includes a first lens 10, a second lens 20, and a third lens 30 along the same optical axis. The first lens 10 is located on a side near the display screen 40, and the third lens 30 is located on a side near the human eye 01.

[0165] The incident light emitted by the display screen 40 is natural light. A stacking sheet 90 is provided on the second surface 12 of the first lens 10. The stacking sheet 90 includes a second phase retarder 92, a third phase retarder 94, and a second polarizing element 93 therebetween.

[0166] The beam splitter 50 is disposed on the third surface 21 of the second lens 20 , the first phase retarder 60 is disposed on the fourth surface 22 of the second lens 20 , and the first polarizing element 80 and the polarizing reflective element 70 are stacked and disposed on the fifth surface 31 of the third lens 30 ;

[0167] The first surface 11 of the first lens 10 is a free-form surface, and the second surface 12 of the first lens 10 is an aspheric surface or a plane surface; the third surface 21 of the second lens 20 is an aspheric surface, and the fourth surface of the second lens 20 is a plane surface or an aspheric surface; the fifth surface and the sixth surface of the third lens 30 are free-form surfaces;

[0168] The focal length of the first lens 10 is -143 mm, the focal length of the second lens 20 is 16.7 mm, and the focal length of the third lens 30 is 198 mm;

[0169] The focal length of the near-eye display module is 19 mm;

[0170] The total length TTL of the optical system of the near-eye display module is 24.1 mm.

[0171] Tables 4 to 6 show the specific optical parameters of each lens in the near-eye display module provided in this embodiment 2.

[0172] Table 4 Free surface coefficients

[0173]

[0174]

[0175] Table 5 Aspheric coefficients

[0176]

[0177] Table 6 Parameters of each lens

[0178] Material Lens thickness / mm Lens gap / mm The third lens 30 K26R 5.2 0.4 Second lens 20 APEL 7 0.3 First lens 10 APEL 5.8 2.6

[0179] Regarding the near-eye display module provided in the above embodiment 2, its optical performance can be as follows: Figures 10 to 13 As shown: Figure 10 This is a schematic diagram of the point diagram of the near-eye display module. Figure 11 This is the MTF curve of the near-eye display module. Figure 12 This is the field curvature distortion diagram of the near-eye display module. Figure 13 This is the vertical axis chromatic aberration diagram of the near-eye display module.

[0180] The point diagram refers to the formation of a diffuse pattern spread over a certain range when many light rays emitted from one point pass through the near-eye display module. Due to aberration, the intersection of the light rays with the image plane is no longer concentrated at the same point. It can be used to evaluate the imaging quality of the near-eye display module. Figure 10 As shown, the maximum value of the image point in the spot diagram corresponds to the maximum field of view, and the maximum value of the image point in the spot diagram is less than 11 μm.

[0181] The MTF curve is a modulation transfer function graph that represents the imaging clarity of the near-eye display module through the contrast of black and white line pairs. Figure 11 As shown, the MTF is >0.2 at 60lp / mm, and the image is clear.

[0182] The distortion diagram reflects the difference in image plane position when different fields of view form clear images. Figure 12 As shown in the figure, the maximum distortion occurs in the first field of view, and the absolute value is less than 35%. The field curvature diagram reflects the difference in the image plane position at different fields of view to form a clear image, see Figure 12 , the maximum field curvature occurs near 1 field of view, and the maximum value is less than 0.2mm.

[0183] Vertical axial chromatic aberration is also called chromatic aberration of magnification. It mainly refers to the difference in the focal position of blue light and red light on the image plane when a complex main light on the object side is transformed into multiple light rays due to the dispersion of the refraction system. Figure 13 As shown in the figure, the maximum color difference value of the near-eye display module is less than 190μm.

[0184] It should be noted that astigmatism is the difference in imaging between the horizontal and vertical directions, such as Figure 7 As shown, there are two lines on the field curvature diagram, divided into: T line and S line, representing the vertical and horizontal directions respectively. The difference between these two directions is astigmatism.

[0185] The astigmatism of the above-mentioned embodiment 1 and embodiment 2 is both less than 0.1 mm. Figure 14 The astigmatism of the aspheric solution with the same specifications is greater than 0.2mm. It can be seen that the optical solution provided by this application can effectively reduce the astigmatism of the near-eye display module, which is conducive to improving the imaging quality.

[0186] According to another aspect of an embodiment of the present application, a wearable device is further provided, comprising a housing and the near-eye display module as described above.

[0187] The wearable device is, for example, a head-mounted display device.

[0188] The head-mounted display device is, for example, a VR head-mounted device, including VR glasses or a VR helmet, etc., and the embodiments of the present application do not impose specific restrictions on this.

[0189] The specific implementation of the wearable device of the embodiment of the present application can refer to the above-mentioned embodiments of the near-eye display module, and therefore at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be repeated here one by one.

[0190] The above embodiments focus on the differences between the various embodiments. As long as the different optimization features between the various embodiments are not contradictory, they can be combined to form a better embodiment. Considering the simplicity of the text, they will not be repeated here.

[0191] Although some specific embodiments of the present application have been described in detail by way of example, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present application. It should be understood by those skilled in the art that the above examples may be modified without departing from the scope and spirit of the present application. The scope of the present application is defined by the appended claims.

Claims

1. A near-eye display module, characterized in that: The imaging lens assembly comprises a beam splitter element (50), a first phase retarder (60) and a polarization reflection element (70); wherein the first phase retarder (60) is located between the beam splitter element (50) and the polarization reflection element (70); The imaging lens group comprises a first lens (10), a second lens (20) and a third lens (30) arranged in sequence along the same optical axis, and at least one free-form surface is provided in the imaging lens group, wherein the absolute value of the difference between the sagittal height of the free-form surface at the same aperture position along a first direction and along a second direction is set to be less than 1 mm; wherein the first direction is perpendicular to the second direction, and the first direction is the height direction of the free-form surface; The absolute value of the ratio of the combined focal length of the second lens (20) and the third lens (30) to the focal length of the first lens (10) satisfies ≤0.3; The light splitting element (50) is arranged between the second lens (20) and the first lens (10), and the first phase retarder (60) and the polarization reflection element (70) are arranged in sequence between the second lens (20) and the third lens (30).

2. The near-eye display module according to claim 1, wherein: The absolute value of the sag of the free-form surface at a 21.2 mm diameter along the first direction is 0.75 mm, and the absolute value of the sag of the free-form surface at a 21.2 mm diameter along the second direction is 0.52 mm.

3. The near-eye display module according to claim 1, wherein: The astigmatism of the near-eye display module is less than 0.1 mm.

4. The near-eye display module according to claim 1, wherein: The surface shapes of the first lens (10), the second lens (20) and the third lens (30) include free-form surfaces, aspherical surfaces or plane surfaces.

5. The near-eye display module according to claim 4, wherein: The focal length φ1 of the first lens (10) is: -143 mm or -55 mm; The focal length φ2 of the second lens (20) is: 14.8 mm or 16.7 mm; The focal length φ3 of the third lens (30) is: 198 mm or 226 mm.

6. The near-eye display module according to claim 4, wherein: The near-eye display module further includes a display screen (40), the first lens (10) is located on a side close to the display screen (40), and the display screen (40) is configured to emit circularly polarized light or natural light; When the light emitted by the display screen (40) is natural light, a superimposed sheet (90) is provided on either side of the first lens (10) to convert the natural light emitted by the display screen (40) into circularly polarized light; The stacked sheet (90) includes a second phase retarder (92), a third phase retarder (94), and a second polarization element (93) between the second phase retarder (92) and the third phase retarder (94).

7. The near-eye display module according to claim 6, wherein: The overlapping sheet (90) is provided on a surface of the first lens (10) away from the display screen (40); The surface of the first lens (10) away from the display screen (40) is an aspherical surface or a plane surface; The surface of the first lens (10) close to the display screen (40) is a free-form surface.

8. The near-eye display module according to claim 7, wherein: The near-eye display module further includes a first polarizing element (80); The light splitting element (50) is provided on a surface of the second lens (20) close to the display screen (40), and the first phase retarder (60) is provided on a surface of the second lens (20) away from the display screen (40); The polarized reflection element (70) and the first polarizing element (80) are stacked and arranged on a surface of the third lens (30) close to the display screen (40).

9. The near-eye display module according to claim 8, wherein: The surface of the second lens (20) close to the display screen (40) is a free-form surface or an aspherical surface, and the surface of the second lens (20) away from the display screen (40) is an aspherical surface or a plane; The surface of the third lens (30) close to the display screen (40) is a free-form surface or an aspherical surface, and the surface of the third lens (30) away from the display screen (40) is a free-form surface.

10. The near-eye display module according to any one of claims 1 to 9, characterized in that: The focal length of the near-eye display module is 14 mm to 25 mm.

11. The near-eye display module according to claim 10, wherein: The total optical length TTL of the near-eye display module is: TTL≤25mm.

12. A wearable device, characterized in that: include: case; as well as The near-eye display module according to any one of claims 1 to 11.

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