Near-eye display modules and head-mounted display devices

Abstract

The embodiments of the present application provide a near-eye display module and a head-mounted display device; wherein the near-eye display module includes an imaging lens group and a beam splitter, a first phase retarder, and a polarizing reflective element disposed within the imaging lens group, wherein the first phase retarder is located between the beam splitter and the polarizing reflective element; the imaging lens group includes a first lens, a second lens, and a third lens in sequence along the same optical axis, the beam splitter is located on either side of the second lens, and the first phase retarder and the polarizing reflective element are located between the second lens and the third lens; the ratio of the focal length f3 of the third lens to the outer diameter D3 of the third lens is 4 to 8, and the ratio of the focal length f of the polarizing reflective element to the axial distance L between the beam splitter and the polarizing reflective element is 30 to 40. The near-eye display module of the embodiments of the present application has the characteristics of small longitudinal size and good imaging quality.

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 head-mounted display device. Background Art

[0002] In recent years, virtual reality (VR) technology has been rapidly applied in head-mounted display devices (HMDs). 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 HMD.

[0003] Optical modules based on a folded optical path (pancake) have smaller dimensions along the optical axis (horizontally), which helps reduce the thickness of head-mounted display devices and achieves a thinner and lighter head-mounted display. However, with current technology, folded optical path optical modules achieve smaller dimensions along their optical axis, but cannot be reduced in the direction perpendicular to the optical axis. The resulting head-mounted display device can only have a smaller dimension in one direction, and its overall size remains large, which to some extent affects the user's wearing experience. Summary of the Invention

[0004] The purpose of this application is to provide a new technical solution for a near-eye display module and a head-mounted display device, which can reduce the longitudinal size of the near-eye display module and reduce the incident angle of light entering the polarized reflective element.

[0005] 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 element, a first phase retarder, and a polarizing reflective element disposed within the imaging lens assembly, wherein the first phase retarder is located between the beam splitter element and the polarizing reflective element;

[0006] The imaging lens assembly includes a first lens, a second lens, and a third lens in sequence along the same optical axis, the beam splitter is located on either side of the second lens, and the first phase retarder and the polarizing reflective element are located between the second lens and the third lens;

[0007] The ratio of the focal length f3 of the third lens to the outer diameter D3 of the third lens is 4-8, and the ratio of the focal length f of the polarizing reflection element to the axial distance L between the beam splitting element and the polarizing reflection element is 30-40.

[0008] Optionally, the first lens, the second lens and the third lens each include an effective optical area and a non-light-transmitting area surrounding the outer periphery of the effective optical area, and a radial dimension of the non-light-transmitting area on any one of the first lens, the second lens and the third lens is T, and T ≥ 1 mm.

[0009] Optionally, the outer diameter value of the lens with the largest outer diameter in the imaging lens assembly is D max ;

[0010] The first lens, the second lens and the third lens each include an effective optical area and a non-light-transmitting area surrounding the effective optical area;

[0011] The radial dimension T of the non-light-transmitting area on any one of the first lens, the second lens, and the third lens is greater than the radial dimension D max The ratio is 0.01~0.1.

[0012] Optionally, the longitudinal height of the near-eye display module is less than 50 mm, and the longitudinal direction is a direction perpendicular to the optical axis.

[0013] Optionally, after the incident light enters the imaging lens assembly, the incident angle of the incident light entering the polarized reflective element is less than 10 degrees.

[0014] Optionally, the optical power of the second lens and the third lens is positive.

[0015] Optionally, a combined focal length of the second lens and the third lens is 15 mm to 20 mm.

[0016] Optionally, the combined focal length of the second lens and the third lens is 18.6 mm.

[0017] Optionally, the near-eye display module further includes a display screen, and the display screen is located on a side of the first lens away from the second lens;

[0018] The display screen is configured to emit circularly polarized light or natural light;

[0019] 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.

[0020] Optionally, the overlapping sheet is provided on a surface of the first lens away from the display screen;

[0021] The stacked plate includes a second phase retarder, a second polarizing element, and a third phase retarder, wherein the second polarizing element is located between the second phase retarder and the third phase retarder.

[0022] Optionally, a first polarizing element is further provided in the imaging lens assembly, the first polarizing element and the polarized reflective element are stacked to form a composite film, and the composite film is provided on a surface of the third lens close to the second lens;

[0023] The beam splitter is disposed on a surface of the second lens close to the first lens, and the first phase retarder is disposed on a surface of the second lens away from the first lens.

[0024] Optionally, the optical power of the first lens is

[0025] In a second aspect, the present application provides a head-mounted display device, the head-mounted display device comprising: a housing; and

[0026] The near-eye display module as described in the first aspect.

[0027] According to an embodiment of the present application, a near-eye display module is provided, which has a folded optical path structure design. By controlling the optical parameters of the lens on the side close to the human eye and the distance parameters between the spectroscopic element and the polarized reflective element, the longitudinal size of each lens in the near-eye display module can be reduced, thereby reducing the longitudinal size of the entire near-eye display module. At the same time, the incident angle of the light entering the polarized reflective element after entering the imaging lens group can be reduced, and the corresponding reflectivity and transmittance of the polarized light will be higher, which is conducive to improving optical efficiency.

[0028] 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

[0029] 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.

[0030] Figure 1 A schematic diagram of the structure of a near-eye display module provided in an embodiment of the present application;

[0031] Figure 2 A schematic diagram of a superimposed sheet provided on the surface of the first lens in the near-eye display module provided in an embodiment of the present application;

[0032] Figure 3 A schematic diagram of a first phase retarder and a first anti-reflection film provided on the surface of the second lens in the near-eye display module provided in an embodiment of the present application;

[0033] Figure 4 A schematic diagram of a composite film provided on the surface of the third lens in the near-eye display module provided in an embodiment of the present application;

[0034] Figure 5 for Figure 1 The spot diagram of the near-eye display module is shown;

[0035] Figure 6 for Figure 1 The MTF curve diagram of the near-eye display module shown;

[0036] Figure 7 for Figure 1 The field curvature distortion diagram of the near-eye display module shown;

[0037] Figure 8 for Figure 1 The vertical axis chromatic aberration diagram of the near-eye display module is shown.

[0038] Description of reference numerals:

[0039] 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; 50. Screen protection glass; 60. Overlay; 61. Second anti-reflection film; 62. Second phase retarder; 63. Second polarizing element; 64. Third phase retarder; 70. Spectral element; 80. First phase retarder; 81. First anti-reflection film; 90. Composite film; 91. Polarized reflective element; 92. First polarizing element; 01. Human eye; 02. Incident light. DETAILED DESCRIPTION

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] According to one aspect of an embodiment of the present application, a near-eye display module is provided. The near-eye display module can be suitable for use in a head-mounted display (HMD), such as a VR headset. The VR headset may include, for example, VR glasses or a VR helmet, which are not specifically limited in the present embodiment.

[0046] The embodiment of the present application provides a near-eye display module, such as Figure 1 As shown, the near-eye display module includes an imaging lens assembly and a beam splitter 70, a first phase retarder 80, and a polarizing reflective element 91 disposed within the imaging lens assembly, wherein the first phase retarder 80 is located between the beam splitter 70 and the polarizing reflective element 91; the imaging lens assembly includes a first lens 10, a second lens 20, and a third lens 30 in sequence along the same optical axis, the beam splitter 70 is located on either side of the second lens 20, and the first phase retarder 80 and the polarizing reflective element 91 are located between the second lens 20 and the third lens 30;

[0047] The ratio of the focal length f3 of the third lens 30 to the outer diameter D3 of the third lens 30 is 4-8, and the ratio of the focal length f of the polarizing reflection element 91 to the axial distance L between the beam splitter 70 and the polarizing reflection element 91 is 30-40.

[0048] The near-eye display module provided in the embodiments of the present application is an optical module based on a folded optical path (pancake). Specifically, the beam splitter element 70, the first phase retarder 80, and the polarizing reflector 91 are rationally arranged between the lenses in the imaging lens assembly to form a folded optical path between the different lenses.

[0049] In the near-eye display module of the embodiment of the present application, see Figure 1 The third lens 30 is, for example, the first lens closest to the human eye O1 / aperture. By controlling the ratio of the focal length f3 of the third lens 30 to its outer diameter D3 to 4-8, and adjusting the focal length f of the polarizing reflective element 91 so that its ratio to the axial distance L between the beam splitting element 70 and the polarizing reflective element 91 is controlled to 30-40, the longitudinal dimensions of each lens in the imaging lens assembly can be reduced through reasonable adjustment of the optical parameters in the module, thereby reducing the longitudinal dimensions of the near-eye display module. Furthermore, based on the structural design of the folded optical path, the lateral dimensions of the near-eye display module can be reduced, making the entire near-eye display module smaller, more suitable for user wear, and enhancing the user's wearing experience and comfort.

[0050] Furthermore, by controlling the ratio of the focal length f3 of the third lens 30 to its outer diameter D3 within a range of 4 to 8, and adjusting the focal length f of the polarizing reflective element 91 so that its ratio to the axial distance L between the beam splitter 70 and the polarizing reflective element 91 is controlled to be 30 to 40, another technical effect can be achieved: reducing the angle of incidence of the polarizing reflective element 91. Specifically, when light enters the imaging lens assembly, the angle of incidence of the polarizing reflective element 91 is significantly reduced. A smaller angle corresponds to higher reflectivity and transmittance of the polarized light, which improves optical efficiency and, therefore, imaging quality.

[0051] The near-eye display module proposed in the embodiment of the present application is configured to: Figure 1 By adjusting the size and focal length of the third lens 30 in the near-eye display module, along with adjusting the optical parameters of the optical elements forming the folded optical path, the entire near-eye display module can be miniaturized in both the horizontal and vertical directions, while significantly improving light efficiency. This allows head-mounted display devices, such as AR display devices, incorporating the near-eye display module to achieve superior image display performance.

[0052] The near-eye display module provided in the embodiment of the present application is a folded optical path, which includes, in addition to the imaging lens group, a spectrometer, a phase delay device and a polarization reflection element. These optical elements (optical films) can be used to form a folded optical path between the lenses of the imaging lens group, so that the light can be folded back therein, which can be used to extend the propagation path of the light and facilitate the final clear imaging.

[0053] In the near-eye display module of the embodiment of the present application, the number of lenses includes but is not limited to the three mentioned above, and the number of lenses can be flexibly adjusted according to specific needs. Among them, as the number of lenses in the folded optical path increases, the imaging quality of the near-eye display module can be improved, but it will also affect the size of the near-eye display module along the optical axis direction (transverse direction), resulting in a larger volume and increased weight of the near-eye display module. In the embodiment of the present application, taking into account many factors such as the volume, weight, imaging quality and production cost of the near-eye display module, it is more preferred to design three lenses in the optical path.

[0054] The light splitting element 70 is, for example, a semi-transmissive and semi-reflective film.

[0055] The light splitting element 70 can transmit a portion of light and reflect another portion of light.

[0056] It should be noted that the reflectivity and transmittance of the light-splitting element 70 can be flexibly adjusted according to specific needs, and this is not limited in the embodiments of the present application.

[0057] Optionally, the reflectivity of the light splitting element 70 is 47% to 53%.

[0058] The first phase retarder 80 is, for example, a quarter-wave plate. Of course, the first phase retarder 80 can also be configured as other phase retarder plates such as a half-wave plate as needed.

[0059] In the near-eye display module of the embodiment of the present application, in the folded light path located near the human eye 01, the first phase retarder 80 can be used to change the polarization state of light, for example, to convert linearly polarized light into circularly polarized light, or vice versa.

[0060] The polarized reflective element 91 is, for example, a polarized reflective film / sheet.

[0061] The polarized reflective element 91 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.

[0062] In the embodiment of the present application, the first phase retarder 80 and the polarizing reflective element 91 cooperate to analyze and transmit light. The polarizing reflective element 91 has a transmission axis, and the angle between the transmission axis of the polarizing reflective element 91 and the fast axis or slow axis of the first phase retarder 80 is, for example, 45°.

[0063] The arrangement positions of the beam splitter 70, the first phase retarder 80, and the polarizing reflective element 91 within the imaging lens assembly are relatively flexible and can be arranged, for example, between the first lens 10, the second lens 20, and the third lens 30 as needed. However, it must be ensured that the first phase retarder 80 is located between the beam splitter 70 and the polarizing reflective element 91.

[0064] Optionally, the beam splitter 70 may be positioned at a suitable location on the side of the second lens 20 that is close to the first lens 10; and the first phase retarder 80 and the polarizing reflective element 91 may be independently positioned at suitable locations between the second lens 20 and the third lens 30. In this way, the beam splitter 70, the first phase retarder 80, and the polarizing reflective element 91 are independently positioned, which increases the degree of freedom in optical path design and facilitates adjustment of the alignment accuracy of the various optical components.

[0065] The beam splitter 70 , the first phase retarder 80 , and the polarized reflective element 91 may be disposed on surfaces of different lenses, respectively. This assembly method is relatively simple.

[0066] Of course, the light splitting element 70 , the first phase retarder 80 and the polarization reflection element 91 can be respectively disposed on a flat glass and then arranged in the optical path as independent devices.

[0067] The optical path diagram of the near-eye display module of the embodiment of the present application is shown in Figure 1 , the light propagation path is:

[0068] The incident light 02 is circularly polarized light. The incident light 02 enters the imaging lens assembly, is transmitted through the first lens 10 and the second lens 20, is reflected by the polarizing reflection element 91, is transmitted through the first phase retarder 80, is reflected by the beam splitter 70, and is transmitted through the first phase retarder 80 and the third lens 30 before entering the human eye 01 / aperture to display an image.

[0069] The near-eye display module provided in the embodiment of the present application is designed with a folded optical path structure. By controlling the parameters of the lens (the third lens 30) on the side close to the human eye 01, as well as parameters such as the distance between the beam splitting element 70 and the polarized reflection element 91, the longitudinal size of each lens in the near-eye display module can be reduced, thereby reducing the longitudinal size of the entire near-eye display module. At the same time, the incident angle of the light entering the polarized reflection element 91 after entering the imaging lens group can be reduced, and the corresponding reflectivity and transmittance of the polarized light will be higher, which is conducive to improving optical efficiency.

[0070] In some examples of the present application, the first lens 10, the second lens 20, and the third lens 30 each include an effective optical area and a non-light-transmitting area surrounding the effective optical area. The radial dimension of the non-light-transmitting area on any one of the first lens 10, the second lens 20, and the third lens 30 is T, and T is ≥ 1 mm.

[0071] It should be noted that in the imaging lens assembly, each lens should have an effective optical area that is translucent. At the same time, in order to facilitate assembly and support of the lens, each lens itself also has an ineffective optical area located on the periphery of the effective optical area, that is, the above-mentioned non-transparent area.

[0072] In the embodiments of the present application, by adjusting the size of the non-transparent area on each lens in the imaging lens assembly, the overall aperture of the lens can be limited, thereby preventing the lens from being too large in the longitudinal direction and affecting the longitudinal size of the entire near-eye display module. The longitudinal direction refers to the direction perpendicular to the optical axis of the near-eye display module.

[0073] When the size of the non-light-transmitting area of each lens is designed to be ≥1 mm, the diameter of the lens can be reduced, for example, the longitudinal size of the lens can be controlled to 50 mm, or even less than 50 mm.

[0074] In some examples of the present application, the outer diameter value of the lens with the largest outer diameter in the imaging lens assembly is D max The first lens 10, the second lens 20 and the third lens 30 each include an effective optical area and a non-light-transmitting area surrounding the outer periphery of the effective optical area;

[0075] The radial dimension T of the non-light-transmitting area on any one of the first lens 10, the second lens 20 and the third lens 30 is greater than the radial dimension D max The ratio is 0.01~0.1.

[0076] In the imaging lens assembly of the embodiment of the present application, the size of the non-light-transmitting area of the lens is combined with the outer diameter of the lens with the largest outer diameter in the optical path. By controlling the ratio of these two parameters, the longitudinal size of the lens can be reasonably reduced while ensuring excellent imaging quality.

[0077] For example, see Figure 1 The imaging lens assembly includes a first lens 10, a second lens 20, and a third lens 30, wherein the second lens 20 is located between the first lens 10 and the third lens 30, and the outer diameter of the second lens 20 is the largest, and the ratio of the non-light-transmitting areas of the first lens 10, the second lens 20, and the third lens 30 to the outer diameter of the second lens 20 is in a range of 0.01 to 0.1.

[0078] In the present application, it is more preferred that the radial dimension T of the non-light-transmitting area on any one of the first lens 10, the second lens 20 and the third lens 30 is equal to the radial dimension T of the D max The ratio is 0.05 to 0.07, which can make the longitudinal size of the formed near-eye display module smaller while ensuring excellent imaging quality.

[0079] In some examples of the present application, the longitudinal height of the near-eye display module is less than 50 mm, and the longitudinal direction is a direction perpendicular to the optical axis.

[0080] In the near-eye display module proposed in the embodiments of this application, the height of the imaging lens assembly can be, for example, less than 50 mm, meaning that the entire near-eye display module can be less than 50 mm in height. This allows a head-mounted display device incorporating this near-eye display module to be relatively small in height, facilitating a miniaturized and lightweight design for the head-mounted display device and enhancing user comfort.

[0081] Furthermore, the height dimension of the near-eye display module can be, for example, 48 mm, or even smaller. This is significantly smaller than the longitudinal dimension of a conventional optical module. The minimum longitudinal dimension of a conventional optical module is also above 50 mm, typically 60 mm or even larger. The near-eye display module provided in the embodiment of the present application has a smaller longitudinal dimension / height. When assembled in a head-mounted display device, it can save space in the longitudinal direction of the head-mounted display device.

[0082] In some examples of the present application, after the incident light 02 enters the imaging lens assembly, the incident angle of the incident light 02 entering the polarized reflective element 91 is less than 10 degrees.

[0083] In the embodiments of the present application, for example, by controlling parameters such as the third lens 30 near the human eye 01, the beam splitter 70, and the polarizing reflective element 91, the longitudinal dimensions of the near-eye display module are reduced while also reducing the angle of incidence of the polarizing reflective element 91. In other words, the angle at which the incident light ray 02 strikes the polarizing reflective element can be reduced to less than 10 degrees. This improves the reflectivity and transmittance of the polarized light from the polarizing reflective element, enhancing lighting efficiency and resulting in better image quality.

[0084] In some examples of the present application, the optical power of the second lens 20 and the third lens 30 is positive.

[0085] Optionally, the combined optical power of the second lens 20 and the third lens 30 is positive.

[0086] See also Figure 1 The second lens 20 and the third lens 30 can form a lens assembly, with various optical elements arranged between them to form a folded optical path, allowing light to be folded back between the second lens 20 and the third lens 30, extending the light propagation path. When the combined optical power of the second lens 20 and the third lens 30 is set to positive, the angle at which the incident light 02 is transmitted through the second lens 20 and the third lens 30 and enters the polarizing reflective element 91 is relatively small, which helps a large amount of light enter the human eye 01 for imaging.

[0087] The optical power of the second lens 20 is positive. For example, the optical power range of the second lens 20 is

[0088] The center thickness T2 of the second lens 20 is in the range of 3mm<T2<8mm, and the second lens 20 includes two optical surfaces, namely a third surface 21 close to the first lens 10 and a fourth surface 22 close to the third lens 30, see Figure 1 .

[0089] Optionally, see Figure 1 The light splitting element 70 is disposed on the third surface 21 , and the third surface 21 is, for example, an aspherical surface.

[0090] Optionally, see Figure 1 and Figure 3 The first phase retarder 80 is provided on the fourth surface 22, and the fourth surface 22 can be a plane or an aspheric surface.

[0091] In addition, a first anti-reflection film 81 may be selectively provided on the fourth surface 22 . The first anti-reflection film 81 is provided on the fourth surface 22 , and the first phase retarder 80 is provided on a side of the first anti-reflection film 81 away from the fourth surface 22 .

[0092] Anti-reflective film can reduce reflection, reduce reflected energy and improve light efficiency.

[0093] Anti-reflective film can be formed on optical components by pasting or coating to form some interfaces, increase transmittance, reduce reflectivity, thereby reducing image distortion, allowing users to enjoy clearer image quality and reduce glare.

[0094] The focal length of the third lens 30 is positive. For example, the focal length of the third lens 30 is

[0095] The central thickness T3 of the third lens 30 is in the range of 1mm<T3<6mm, and it includes two optical surfaces. Figure 1 , which are respectively a fifth surface 31 close to the second lens 20 and a sixth surface 32 far from the second lens 20 .

[0096] Optionally, the fifth surface 31 and the sixth surface 32 may be designed as aspherical surfaces.

[0097] Optionally, see Figure 1 and Figure 4 The polarization reflection element 91 (transmitting P light and reflecting S light) that forms a folded light path is directly disposed on the fifth surface 31 of the third lens 30 .

[0098] Optionally, an anti-reflection film is also selectively provided on the sixth surface 32 .

[0099] Similar to the first anti-reflection film 81 described above, the anti-reflection film on the sixth surface 32 can reduce reflections, lower reflected energy, and improve light efficiency. This anti-reflection film can also be applied to the optical components by gluing or coating to form interfaces, increasing transmittance and reducing reflectivity, thereby reducing image distortion, allowing users to enjoy clearer image quality and reducing glare.

[0100] In some examples of the present application, the combined focal length of the second lens 20 and the third lens 30 is 15 mm to 20 mm.

[0101] By adjusting the combined focal length of the two lenses on the side close to the human eye 01 and controlling it within the above range, the total optical length of the entire near-eye display module can be reasonably controlled, thereby controlling the lateral size and ensuring the quality of the image formed.

[0102] For example, the combined focal length of the second lens 20 and the third lens 30 is 18.6 mm. This can reduce the total optical length of the near-eye display module, thereby reducing the lateral size of the near-eye display module while maintaining excellent imaging performance, thereby enhancing the user's wearing comfort and visual experience.

[0103] In some examples of the present application, the near-eye display module also includes a display screen 40, which is located on the side of the first lens 10 away from the second lens 20; 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, an overlapping sheet 60 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.

[0104] That is to say, the incident light 02 entering the imaging lens assembly should be circularly polarized light.

[0105] When the display screen 40 emits natural light, the polarization state of the natural light needs to be converted first, so that the natural light is first converted into circularly polarized light and then enters the imaging lens group on the left. Finally, the light emitted by the imaging lens group enters the human eye 01 for imaging.

[0106] Optionally, see Figure 2 The overlapping sheet 60 is arranged on the surface of the first lens 10 away from the display screen 40; the overlapping sheet 60 includes a second phase retarder 62, a second polarizing element 63 and a third phase retarder 64, wherein the second polarizing element 63 is located between the second phase retarder 62 and the third phase retarder 64.

[0107] In the embodiment of the present application, the device for converting natural light into circularly polarized light is the aforementioned laminate 60. The laminate 60 includes, for example, two phase retarders and a polarizing element disposed between the two phase retarders.

[0108] Specifically, see Figure 2The display screen 40 emits natural light, which first passes through a phase retarder (for example, the third phase retarder 64) and remains natural light, then passes through the second polarizing element 63 and becomes linearly polarized light, and then passes through another phase retarder (for example, the second phase retarder 62) and becomes circularly polarized light.

[0109] In the stacked plate 60, 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.

[0110] The overlay 60 is a composite film formed by sandwiching a polarizing film between two quarter-wave plates. In this application, the overlay 60 is designed to be directly attached to any surface of the first lens 10 using, for example, optical adhesive. This assembly method is simple, reduces production costs, and improves product yield.

[0111] In the examples of this application, see Figure 1 The first lens 10 has a central thickness T1 in the range of 1 mm < T1 < 8 mm and includes two optical surfaces, a first surface 11 close to the display screen 40 and a second surface 12 away from the display screen 40. Optionally, the first surface 11 and the second surface 12 are aspherical or flat.

[0112] The overlapping sheet 60 can be provided on the first surface 11 , and of course can also be provided on the second surface 12 , and this is not specifically limited in the present application.

[0113] Please continue to see Figure 2 The laminated sheet 60 includes a second anti-reflection film 61, a second phase retarder 62, a second polarizing element 63 and a third phase retarder 64 stacked in sequence, the second anti-reflection film 61 is connected to the first surface 11, and the second phase retarder 62, the second polarizing element 63 and the third phase retarder 64 are stacked in sequence on the second anti-reflection film 61.

[0114] Optionally, the optical power of the first lens 10 is

[0115] In the near-eye display module provided in the embodiment of the present application, see Figure 1By placing a superimposed sheet 60 between the display screen 40 and the first lens 10, natural light polarization state conversion is achieved. Natural light emitted from 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.

[0116] Optionally, see Figure 1 The light emitting surface of the display screen 40 is provided with a screen protection glass 50.

[0117] The light emitted from the display screen 40 is transmitted through the screen protection glass 50 on the surface and then enters the laminated sheet 60 to undergo polarization state conversion.

[0118] In some examples of this application, see Figure 1 and Figure 4 The imaging lens group is further provided with a first polarizing element 92. The first polarizing element 92 and the polarized reflective element 91 are stacked to form a composite film 90. The composite film 90 is provided on the surface of the third lens 30 close to the second lens 20. The beam splitter 70 is provided on the surface of the second lens 20 close to the first lens 10, and the first phase retarder 80 is provided on the surface of the second lens 20 away from the first lens 10.

[0119] The first polarizing element 92 can be used to reduce stray light.

[0120] In the near-eye display module of the present embodiment, the beam splitter 70 and the first phase retarder 80 are disposed on two surfaces of the second lens 20, and the polarizing reflective element 91 is disposed on one surface of the third lens 30. The beam splitter 70, the first phase retarder 80, and the polarizing reflective element 91 are independently provided. This facilitates adjustment of the distance between the beam splitter 70 and the polarizing reflective element 91, thereby adjusting the ratio of the focal length f of the polarizing reflective element to the axial distance L between the beam splitter and the polarizing reflective element to 30 to 40.

[0121] Of course, the beam splitter 70 and the first phase retarder 80 can be mounted together and disposed on any surface of the second lens 20 , and the polarizing reflective element 91 can be independently disposed on any surface of the third lens 30 .

[0122] In addition, the polarizing reflection element 91 and the first phase retarder 80 can also be mounted together and provided on any surface of the third lens 30, while the spectroscopic element 70 can be independently provided on any surface of the second lens 20. This embodiment of the present application does not impose any specific restrictions on this.

[0123] 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.

[0124] 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.

[0125] The near-eye display module provided in the embodiment of the present application is described in detail below through a specific embodiment.

[0126] Example 1

[0127] See also Figures 1 to 4 The near-eye display module includes: an imaging lens group and a beam splitter 70, a first phase retarder 80, a polarization reflection element 91, and a first polarization element 92 arranged in the imaging lens group; the imaging lens group includes a first lens 10, a second lens 20, and a third lens 30 along the same optical axis, wherein the first lens 10 is located on the side of the near display screen 40, and the third lens 30 is located on the side of the human eye 01. The optical power of the first lens 10 is for, The optical power of the second lens 20 and the third lens 30 is positive, and the combined focal length of the second lens 20 and the third lens 30 is 15 mm to 20 mm;

[0128] The beam splitter 70 is disposed on the third surface 21 of the second lens 20 , the first phase retarder 80 is disposed on the fourth surface 22 of the second lens 20 , and the first polarizing element 92 and the polarizing reflective element 91 are stacked to form a composite film 90 which is then disposed on the fifth surface 31 of the third lens 30 ;

[0129] The incident light 02 emitted by the display screen 40 is natural light. A laminated sheet 60 is provided on the second surface 12 of the first lens 10. The laminated sheet 60 includes a second phase retarder 62, a third phase retarder 64, and a second polarizing element 63 interposed therebetween.

[0130] The ratio of the focal length f3 of the third lens 30 to the outer diameter D3 of the third lens 30 is 4 to 8, and the ratio of the focal length f of the polarizing reflection element 91 to the axial distance L between the beam splitting element 70 and the polarizing reflection element 91 is 30 to 40.

[0131] The outer diameter of the second lens 20, which has the largest outer diameter in the imaging lens assembly, is D max The first lens 10, the second lens 20 and the third lens 30 all include an effective optical area and a non-light-transmitting area surrounding the outer periphery of the effective optical area; the radial size T of the non-light-transmitting area on any one of the first lens 10, the second lens 20 and the third lens 30 is the same as the radial size T of the D max The ratio is 0.01~0.1.

[0132] The vertical height of the near-eye display module provided in Example 1 of the present application is 48 mm, where the vertical direction is perpendicular to the optical axis. Furthermore, after the incident light 02 enters the imaging lens assembly, the incident angle of the incident light 02 into the polarizing reflective element 91 is less than 10 degrees.

[0133] Table 1 shows the specific optical parameters of each lens in the near-eye display module provided in this embodiment 1.

[0134] Table 1

[0135]

[0136] 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.

[0137] The point diagram refers to the many light rays emitted from one point. After passing through the near-eye display module, due to aberration, their intersection with the image plane is no longer concentrated at the same point, but forms a diffuse pattern scattered in a certain range. 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 12 μm.

[0138] 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 >0.3 at 22lp / mm, and the image is clear.

[0139] The distortion diagram reflects the difference in image plane position when different fields of view form clear images, such as Figure 7 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 of different fields of view to form a clear image, such as Figure 7 , the maximum field curvature occurs near 1 field of view, and the maximum value is less than 0.25mm.

[0140] Vertical axis chromatic aberration is also called magnification chromatic aberration, which mainly refers to the difference between the focal positions of blue light and red light on the image plane. Figure 8 As shown in the figure, the maximum color difference value of the near-eye display module is less than 200μm.

[0141] According to another aspect of an embodiment of the present application, a head-mounted display device is further provided, comprising a housing and the near-eye display module as described above.

[0142] 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.

[0143] The specific implementation of the head-mounted display device of the embodiment of the present application can refer to the above-mentioned embodiments of the near-eye display module, so it 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.

[0144] 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.

[0145] 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 near-eye display module comprises an imaging lens group, and a beam splitter element (70), a first phase retarder (80), and a polarized reflective element (91) arranged in the imaging lens group, wherein the first phase retarder (80) is located between the beam splitter element (70) and the polarized reflective element (91); The imaging lens assembly includes a first lens (10), a second lens (20), and a third lens (30) in sequence along the same optical axis; the beam splitter (70) is located on either side of the second lens (20); and the first phase retarder (80) and the polarization reflection element (91) are located between the second lens (20) and the third lens (30); The ratio of the focal length f3 of the third lens (30) to the outer diameter D3 of the third lens (30) is 4 to 8, and the ratio of the focal length f of the polarizing reflection element (91) to the axial distance L between the light splitting element (70) and the polarizing reflection element (91) is 30 to 40; The combined focal length of the second lens (20) and the third lens (30) is 15 mm to 20 mm.

2. The near-eye display module according to claim 1, wherein: The first lens (10), the second lens (20) and the third lens (30) all include an effective optical area and a non-light-transmitting area arranged on the outer periphery of the effective optical area, and the radial size of the non-light-transmitting area on any one of the first lens (10), the second lens (20) and the third lens (30) is T, and T is ≥ 1 mm.

3. The near-eye display module according to claim 1, wherein: The outer diameter of the lens with the largest outer diameter in the imaging lens assembly corresponds to D max ; The first lens (10), the second lens (20) and the third lens (30) all include an effective optical area and a non-light-transmitting area arranged on the outer periphery of the effective optical area; The radial dimension T of the non-light-transmitting area on any one of the first lens (10), the second lens (20) and the third lens (30) is equal to the radial dimension T of the D max The ratio is 0.01~0.

1.

4. The near-eye display module according to claim 1, wherein: The longitudinal height of the near-eye display module is less than 50 mm, and the longitudinal direction is a direction perpendicular to the optical axis.

5. The near-eye display module according to claim 1, wherein: After the incident light (02) enters the imaging lens assembly, the incident angle of the incident light entering the polarized reflection element (91) is less than 10 degrees.

6. The near-eye display module according to claim 1, wherein: The optical power of the second lens (20) and the third lens (30) is positive.

7. The near-eye display module according to claim 1, wherein: The combined focal length of the second lens (20) and the third lens (30) is 18.6 mm.

8. The near-eye display module according to any one of claims 1 to 7, characterized in that: The near-eye display module further includes a display screen (40), wherein the display screen (40) is located on a side of the first lens (10) facing away from the second lens (20); 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 (60) is provided on either side of the first lens (10) and can be used to convert the natural light emitted by the display screen (40) into circularly polarized light.

9. The near-eye display module according to claim 8, wherein: The overlapping sheet (60) is provided on a surface of the first lens (10) away from the display screen (40); The stacked plate (60) includes a second phase retarder (62), a second polarizing element (63) and a third phase retarder (64), wherein the second polarizing element (63) is located between the second phase retarder (62) and the third phase retarder (64).

10. The near-eye display module according to claim 1, wherein: A first polarizing element (92) is further provided in the imaging lens assembly. The first polarizing element (92) and the polarized reflective element (91) are stacked to form a composite film (90). The composite film (90) is provided on a surface of the third lens (30) close to the second lens (20). The light splitting element (70) is arranged on a surface of the second lens (20) close to the first lens (10), and the first phase retarder (80) is arranged on a surface of the second lens (20) far from the first lens (10).

11. The near-eye display module according to claim 1, wherein: The optical power of the first lens (10) is φ1, -0.01<φ1<0.

01.

12. A head-mounted display 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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