Display module and head-mounted display device

Abstract

The invention relates to the technical field of optics, and particularly provides a display module and a head-mounted display device. The display module comprises a light-emitting assembly and a display module, the light incident side of the thin pancake display assembly is configured to receive light emitted by the light emitting assembly; the pancake display assembly comprises a lens, a semi-transparent and semi-reflective film, a first phase delay film and a reflective polarizing film. Wherein the number of the lenses is multiple, the lenses at least comprise a Fresnel lens, and the first phase delay film and the reflection polarizing film are arranged on any one of the lenses in a stacked mode in the direction away from the light-emitting assembly. The semi-transparent and semi-reflective film is arranged on any lens between the display assembly and the first phase delay film and the reflective polarizing film which are arranged in a stacked mode. Based on the pancake folded light path, the Fresnel lens is matched, so that the total length of the device can be shortened, the FOV can be increased, and the imaging quality is improved.

Description

Technical Field

[0001] The present invention relates to the field of optical technology, and specifically provides a display module and a head-mounted display device. Background Art

[0002] VR (Virtual Reality) is a system that can create and experience a virtual world. It uses computer technology to generate a virtual environment that is similar to or completely new to the real environment, allowing users to immerse themselves in it and gain an immersive feeling. VR optical systems are mainly divided into aspheric lenses, Fresnel lenses, and pancake solutions. The pancake solution is mainly derived from its shape, which is as thin as a "pancake", and usually refers to a small, light, and thin lens. The solution mainly uses the principle of polarized light and adopts a folded optical path design. After the image source enters the semi-reflective and semi-transparent beam splitter, the light is folded back and forth between the lens, phase delay plate, and reflective polarizing film many times, and finally emitted from the reflective polarizing film into the human eye.

[0003] The existing optical system solutions have their own advantages and disadvantages, and VR products have always been problems that have plagued the industry, such as heavy weight, small field of view, and poor wearing experience. Summary of the invention

[0004] In order to overcome the above-mentioned defects, the present invention proposes a display module and a head-mounted display device, which, on the basis of being light and thin, also improve the imaging quality of the lens edge, expand the field of view, and enhance the user's immersive experience.

[0005] In a first aspect, the present invention provides a display module, comprising:

[0006] Light emitting components;

[0007] a pancake display assembly, wherein a light incident side of the pancake display assembly is configured to receive light emitted by the light emitting assembly;

[0008] The pancake display assembly includes a lens, a semi-transparent and semi-reflective film, a first phase delay film and a reflective polarizing film; wherein, there are multiple lenses, and the lenses include at least one Fresnel lens, the first phase delay film and the reflective polarizing film are stacked and arranged on any one of the multiple lenses in a direction away from the light-emitting assembly, and the semi-transparent and semi-reflective film is arranged on any one of the lenses between the display assembly and the stacked first phase delay film and the reflective polarizing film.

[0009] Furthermore, there are two lenses, namely a convex lens and a Fresnel lens;

[0010] The convex lens and the Fresnel lens are arranged in sequence along a direction away from the light-emitting component.

[0011] Further, one side of the Fresnel lens has a sawtooth structure, the sawtooth structure is arranged toward one side of the light-emitting component, the other side of the Fresnel lens is a plane, and a first phase delay film and a reflective polarizing film are arranged on the plane of the Fresnel lens;

[0012] A semi-transparent and semi-reflective film is arranged on one side of the convex lens facing the light-emitting component.

[0013] Further, one side of the Fresnel lens has a sawtooth structure, the sawtooth structure is arranged toward the light-emitting side of the pancake display assembly, the other side of the Fresnel lens is an aspherical surface, and the side of the Fresnel lens having the sawtooth structure is provided with a first phase delay film and a reflective polarizing film;

[0014] A semi-transparent and semi-reflective film is arranged on one side of the convex lens facing the light-emitting component.

[0015] Further, one side of the Fresnel lens has a sawtooth structure, the sawtooth structure is arranged toward one side of the light-emitting component, the other side of the Fresnel lens is an aspherical surface or a plane, and the aspherical surface or the plane of the Fresnel lens is provided with a first phase delay film and a reflective polarizing film;

[0016] A semi-transparent and semi-reflective film is disposed on one side of the convex lens facing the light-emitting side of the display module.

[0017] Furthermore, the convex lens is an aspherical lens.

[0018] Furthermore, 0.88<total length of the display module / focal length of the pancake display assembly<0.9, 14 mm<total length of the display module<15 mm.

[0019] Furthermore, there are two lenses, namely a Fresnel lens and a convex-concave lens;

[0020] The Fresnel lens and the convex-concave lens are arranged in sequence in a direction away from the light-emitting component;

[0021] One side of the Fresnel lens is a convex surface, the convex surface of the Fresnel lens is arranged toward one side of the light-emitting component, and the other side of the Fresnel lens has a sawtooth structure; a semi-transparent and semi-reflective film is arranged on the convex surface of the Fresnel lens;

[0022] One side of the convex-concave lens is a concave surface, which is arranged toward one side of the light-emitting component, and the other side is a convex surface. A first phase delay film and a reflective polarizing film are arranged on the convex surface of the convex-concave lens.

[0023] Furthermore, the thickness of the Fresnel lens is less than 6 mm, the absolute value of the radius of curvature of the side of the Fresnel lens with a serrated structure is less than 70 mm; the space between the convexo lens and the Fresnel lens is less than 5.5 mm, and the total length of the display module is less than 15 mm; 0.88<total length of the display module / focal length of the pancake display assembly<0.9.

[0024] Further, the refractive index n1 of the Fresnel lens is 1.96, the Abbe number is 17, the aperture is greater than 40 mm, the radius of curvature of the side of the Fresnel lens with a sawtooth structure is 64.1 mm, the radius of curvature of the convex surface of the Fresnel lens is 49.5 mm, and the thickness of the Fresnel lens is 2 mm;

[0025] The refractive index n2 of the convex-concave lens is 1.7, the Abbe number is 54, the aperture is greater than 40 mm, the curvature radius of the convex surface of the convex-concave lens is 56 mm, the curvature radius of the concave surface of the convex-concave lens is -714 mm, and the thickness of the convex-concave lens is 3 mm;

[0026] The space between the Fresnel lens and the convex-concave lens is 5.25 mm;

[0027] n1 and n2 satisfy: 1 <n1 / n2<1.1。

[0028] Furthermore, the light emitting component comprises:

[0029] A light emitting element, used for emitting light;

[0030] The dimming element is used to adjust the optical form of the light emitted by the light-emitting element so that the emitted light of the light-emitting component is circularly polarized light.

[0031] Furthermore, the dimming element comprises:

[0032] Polarizer and second phase retardation film;

[0033] Wherein, on a side close to the pancake display assembly, along a direction away from the light-emitting element, the polarizer and the second phase delay film are arranged in sequence.

[0034] Furthermore, the second phase retardation film is a quarter wave plate, and the first phase retardation film is a quarter wave plate.

[0035] Furthermore, the first phase delay film and the reflective polarizing film are integrally formed with or bonded to any one of the plurality of lenses.

[0036] Furthermore, there are more than three lenses, and the first phase delay film and the reflective polarizing film are arranged on the lens adjacent to the light emitting side of the pancake display assembly, and the first phase delay film and the reflective polarizing film face the light emitting side of the pancake display assembly.

[0037] Furthermore, the semi-transmissive and semi-reflective film is arranged on a lens adjacent to a light incident side of the pancake display assembly, and the semi-transmissive and semi-reflective film faces the light incident side of the pancake display assembly.

[0038] In a second aspect, the present invention provides a head-mounted display device, comprising a head-mounted support component and the display module described in the first aspect, wherein the display module is used to present an image.

[0039] The above one or more technical solutions of the present invention have at least one or more of the following beneficial effects:

[0040] In the technical solution for implementing the present invention, the present invention is based on a pancake folded optical path, and when used with a Fresnel lens, not only can the overall length of the device be shortened, but also the FOV can be increased, thereby improving the imaging quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The disclosure of the present invention will become more easily understood with reference to the accompanying drawings. It is easy for those skilled in the art to understand that these drawings are only for illustrative purposes and are not intended to limit the scope of protection of the present invention. In addition, similar numbers in the figures are used to represent similar components, among which:

[0042] Figure 1 is a schematic diagram of the main components of a display module according to Embodiment 1 of the present invention;

[0043] Figure 2 is a schematic diagram of the main components of a display module according to Embodiment 2 of the present invention;

[0044] Figure 3 is a schematic diagram of a first phase retardation film and a reflective polarizing film in a display module according to Embodiment 2 of the present invention being arranged on a surface having a sawtooth structure;

[0045] Figure 4 is a schematic diagram of the main components of a display module according to Embodiment 3 of the present invention;

[0046] Figure 5 is a schematic diagram of an optical structure simulated by using Zemax according to Example 4 of the present invention;

[0047] Figure 6 4 is a graph showing the test results of MTF according to Example 4 of the present invention;

[0048] Figure 7 is a graph showing the test results of field curvature according to Example 4 of the present invention;

[0049] Figure 8 is a distortion test result diagram according to Example 4 of the present invention;

[0050] Fig. 9 is a schematic diagram of the main components of a display module according to Embodiment 5 of the present invention;

[0051] Fig.10 It is a schematic diagram of the main components of the display module according to Example 6 of the present invention.

[0052] Reference numerals list :

[0053] 1 convex lens; 2 Fresnel lens; 3 light emitting assembly; 3-1 light emitting element; 3-2 polarizer; 3-3 second phase delay film; 4 first phase delay film; 5 reflective polarizing film; 6 semi-transparent and semi-reflective film; 7 polarizer; 8 second phase delay film; 9 lens with convex lens structure; 10 first lens; 11 second lens; 12 third lens; 13 fourth lens. DETAILED DESCRIPTION

[0054] Some embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0055] The present invention provides a display module, referring to Figure 1-4 as well as Figure 8-10 include:

[0056] Light emitting components;

[0057] A pancake display assembly, wherein the light incident side of the pancake display assembly is configured to receive light emitted by the light emitting assembly;

[0058] The pancake display assembly includes a lens, a semi-transparent and semi-reflective film, a first phase delay film and a reflective polarizing film; wherein, there are multiple lenses, and the lenses include at least one Fresnel lens, the first phase delay film and the reflective polarizing film are stacked and arranged on any one of the multiple lenses in a direction away from the light-emitting assembly, and the semi-transparent and semi-reflective film is arranged on any one of the lenses between the display assembly and the stacked first phase delay film and the reflective polarizing film.

[0059] The positions and functions of the components of the display module of the present invention are described.

[0060] 1. The light-emitting component is used to emit light. The light-emitting component is located on the light-incident side of the pancake display component and serves as the light source of the pancake display component.

[0061] 2. The pancake display component is used to receive the light emitted by the light-emitting component, usually the received circularly polarized light, which is then optically processed inside the pancake display component to adjust the optical state of the light and finally emit light of a preset optical form.

[0062] The core components of the Pancake Display component are:

[0063] (1) Lens.

[0064] The number is two or more, and at least one of them is a Fresnel lens. Figures 1 to 3 as well as Figure 8 The case of two lenses is shown. Fig. 9 The case of three lenses is shown. Fig.10 The case of four lenses is shown. Although not shown in the drawings and examples, the present invention can also be applied to the case of more lenses.

[0065] (2) A first phase retardation film and a reflective polarizing film are stacked.

[0066] The first phase delay film and the reflective polarizing film are laminated to form a film assembly, which is combined with any one of the multiple lenses by integral molding or bonding. The first phase delay film is used to phase retard light. The reflective polarizing film can selectively transmit or reflect light in a specific polarization direction, thereby achieving folding and polarization conversion of light, and finally injecting the processed light into the human eye. Because the light emitted by the reflective polarizing film is ultimately incident on the human eye, the reflective polarizing film is farther away from the light-emitting component than the first phase delay film.

[0067] (3) Semi-transparent and semi-reflective film.

[0068] The semi-transparent and semi-reflective film is closer to the light-emitting component than the first phase delay film and the reflective polarizing film that are stacked. The "transparent" in the semi-transparent and semi-reflective film refers to the transmission of light emitted by the light-emitting component, and the "reflection" in the semi-transparent and semi-reflective film refers to the re-reflection of the reflected light from the reflective polarizing film.

[0069] The carriers of the first phase retardation film, the reflective polarizing film, and the semi-transparent and semi-reflective film need to be combined on any one of the lenses to achieve corresponding optical performance. Usually, the lens combined with the film assembly composed of the first phase retardation film and the reflective polarizing film is not the same lens as the lens combined with the semi-transparent and semi-reflective film.

[0070] Since light is reflected back and forth between the semi-transmissive mirror (lens combined with a semi-transmissive film) and the reflective polarizing film, the semi-transmissive film is disposed between the display assembly and the stacked first phase retardation film and the reflective polarizing film.

[0071] The working process of the pancake display component:

[0072] The function of the pancake display component has a similar optical processing process to the existing pancake optical path. Based on the principle of polarized light, the reflective polarizing film selectively reflects and projects different polarized light, and cooperates with the first phase delay film to adjust the polarized light form, so that the light can be reflected back and forth between the semi-transparent and semi-reflective mirror (a lens combined with a semi-transparent and semi-reflective film) and the reflective polarizing film, and finally transmitted from the reflective polarizing film. When the display module is used in VR, the light transmitted from the reflective polarizing film finally enters the human eye.

[0073] The following describes the structure of the light emitting assembly 3.

[0074] Light emitting element 3-1, used for emitting light;

[0075] The dimming element is used to adjust the optical form of the light emitted by the light-emitting element so that the emitted light of the light-emitting component is circularly polarized light.

[0076] In one embodiment, the dimming element comprises:

[0077] Polarizer 3-2 and second phase retardation film 3-3;

[0078] Among them, on a side close to the pancake display assembly, along a direction away from the light-emitting element, the polarizer 3-2 and the second phase delay film 3-3 are arranged in sequence.

[0079] In one embodiment, the second phase delay film is a quarter wave plate, and the first phase delay film is a quarter wave plate.

[0080] In one embodiment, the first phase delay film and the reflective polarizing film are integrally formed with or bonded to any one of the plurality of lenses.

[0081] In one embodiment, the first phase delay film and the reflective polarizing film are integrally injection-molded with any one of the plurality of lenses.

[0082] In this embodiment, the lens and the film material are realized together by in-mold injection molding. This process can integrate the lens and the film material into the product at one time, thereby improving production efficiency and product performance.

[0083] Advantages of lens and film in-mold injection molding:

[0084] ① High integration: The lens and film material are injected into the product at one time, which reduces the assembly process and improves the integration of the product.

[0085] ② High production efficiency: The in-mold injection molding process can complete the manufacture of lenses and film materials at one time, reducing the production cycle and improving production efficiency.

[0086] ③Stable product quality: The in-mold injection molding process can ensure the precision and quality of lenses and film materials, reducing product quality problems caused by the assembly process.

[0087] ④ Reduce costs: Reduce assembly steps and reduce production costs.

[0088] In addition, the technical difficulties and solutions of lens and film in-mold injection molding:

[0089] ①Mold design: Mold design needs to take into account the precision and smoothness of the lens and film, as well as the fluidity and cooling time during the injection molding process. Therefore, high-precision mold design is required to optimize the injection molding process parameters to ensure the precision and quality of the lens and film.

[0090] ②Material selection: The material selection of lenses and films needs to take into account their optical properties, mechanical properties and chemical stability. Therefore, it is necessary to select materials with excellent optical properties, mechanical properties and chemical stability to ensure the performance and life of the product.

[0091] ③Injection molding process: The injection molding process needs to take into account the fluidity and cooling time of the lens and film materials, as well as the pressure and temperature control during the injection molding process. Therefore, it is necessary to optimize the injection molding process parameters accordingly, shorten the cooling time through external cooling, and improve productivity.

[0092] In one embodiment, referring to Figures 1 to 4 and Figure 8 There are two lenses, namely a convex lens 1 and a Fresnel lens 2. The convex lens 1 and the Fresnel lens 2 are arranged in sequence in a direction away from the light-emitting component. In other words, the positional relationship between the convex lens 1 and the Fresnel lens 2 is that the convex lens 1 is closer to the light-emitting component than the Fresnel lens 2.

[0093] In one embodiment, referred to as Embodiment 1, refer to Figure 1 The display module of this embodiment includes: a light emitting component 3, a convex lens 1 (lens 1) and a Fresnel lens 2 (lens 2). One side of the Fresnel lens 2 has a sawtooth structure, and the sawtooth structure is arranged toward the light emitting component 3. The other side of the Fresnel lens 2 is a plane, and the plane faces the light emitting side of the pancake display component. A first phase delay film 4 and a reflective polarizing film 5 are stacked in sequence on the plane of the Fresnel lens 2;

[0094] A semi-transparent and semi-reflective film 6 is disposed on one side of the convex lens 1 facing the light-emitting component 3 .

[0095] Lens 1 is an aspherical lens. Lens 2 is a Fresnel lens, which makes the entire optical system thinner and lighter, and maximizes the thinness of Pancake. On the plane of Fresnel lens 2, the first phase delay film 4 and the reflective polarizing film 5 are sequentially attached using a traditional flat film attaching process. The first phase delay film 4 is a 1 / 4 wave plate.

[0096] The light-emitting element 3-1 in the light-emitting component 3 adopts Micro-OLED, and the light emitted by the module is natural light. On the side of the Micro-OLED facing the convex lens 1, a polarizer 3-2 and a second phase delay film 3-3 are sequentially adhered, so that the light emitted by the light-emitting component 3 is right-handed circularly polarized light. The light-emitting element 3-1 can also adopt LCD or Micro LED, etc., as long as the light emitted by the light-emitting component 3 is circularly polarized light.

[0097] This embodiment shows the working process of the module:

[0098] The circularly polarized light emitted by the light-emitting component 3 passes through the semi-transparent and semi-reflective film 6 of lens 1 and enters lens 2, then passes through the first phase delay film 4 to become S-linear polarized light, is reflected by the reflective polarizing film 5, passes through the first phase delay film 4 again to become right-handed circularly polarized light, is then reflected by the semi-transparent and semi-reflective film 6 of lens 1 to become left-handed circularly polarized light, then passes through the first phase delay film 4 and the reflective polarizing film 5 again to become P-linear polarized light, and enters the human eye as the output light of the display module.

[0099] In one embodiment, referred to as Embodiment 2, refer to Figure 2 The display module of this embodiment differs from the display module of Embodiment 1 only in that:

[0100] One side of the Fresnel lens 2 has a sawtooth structure, and the sawtooth structure is arranged toward the light-emitting side of the pancake display assembly. In other words, the sawtooth structure is arranged away from the light-emitting assembly 3. The other side of the Fresnel lens 2 is an aspherical surface, and the side of the Fresnel lens 2 having the sawtooth structure is provided with a first phase delay film 4 and a reflective polarizing film 5;

[0101] A semi-transparent and semi-reflective film 6 is disposed on one side of the convex lens 1 facing the light-emitting component 3 .

[0102] In this embodiment, the side of the Fresnel lens 2 with the sawtooth structure is perfectly injection-molded with the first phase delay film 4 and the reflective polarizing film 5 by in-mold injection molding. Figure 3 After the processing of the Fresnel lens 2 is completed, the lens demoulding can simultaneously complete the corresponding film attachment, and the product has a high degree of integration, eliminating the subsequent film attachment process, which can improve efficiency and reduce costs. The working method of this embodiment is similar to that of embodiment 1, and the optical path process of embodiment 2 can be understood by referring to embodiment 1.

[0103] In one embodiment, referred to as Embodiment 3, refer to Figure 4 The display module of this embodiment differs from the display module of Embodiment 1 only in that:

[0104] One side of the Fresnel lens 2 has a sawtooth structure, and the sawtooth structure is arranged toward one side of the light emitting component 3. The other side of the Fresnel lens 2 is an aspherical surface or a plane. Figure 8 The aspherical surface shown in the figure is a Fresnel lens 3. A first phase delay film 4 and a reflective polarizing film 5 are arranged on the aspherical surface. The side with a serrated structure is to utilize the advantages of the Fresnel lens to perform Fresnelization on the basis of the existing solutions on the market. The advantage of such a design is that the optical machine can be made lighter. The other aspherical surface or plane adopts a curved surface film bonding process or an in-mold injection molding process combined with a first phase delay film 4 and a reflective polarizing film 5 to ensure image quality.

[0105] A semi-transparent and semi-reflective film 6 is disposed on a surface of the convex lens 1 facing the light-emitting side of the display module. In other words, the semi-transparent and semi-reflective film 6 is located on a side of the convex lens 1 facing away from the light-emitting component 3 .

[0106] The optical path of the two-piece display module shown in Examples 1-3 can be further optimized, and the optical parameters satisfy the following relationship: 0.88<total length TL of the display module / focal length f of the pancake display assembly<0.9, 14mm<total length TL of the display module<15mm.

[0107] In one embodiment, referred to as Embodiment 4, the display module of this embodiment differs from the display module of Embodiment 1 only in that:

[0108] There are two lenses, namely Fresnel lens and convex-concave lens;

[0109] The Fresnel lens and the convex-concave lens are arranged in sequence along a direction away from the light-emitting component.

[0110] One side of the Fresnel lens is a convex surface, the convex surface of the Fresnel lens is arranged toward one side of the light-emitting component, and the other side of the Fresnel lens has a sawtooth structure; a semi-transparent and semi-reflective film is arranged on the convex surface of the Fresnel lens;

[0111] One side of the convex-concave lens is a concave surface, which is arranged toward one side of the light-emitting component, and the other side is a convex surface. A first phase delay film and a reflective polarizing film are arranged on the convex surface of the convex-concave lens.

[0112] For Example 4, zemax is used for simulation, as shown in FIG. Figure 5As shown, a pancake-Fresnel optical system with a 90° FOV is designed using a 1.3-inch Micro-OLED module.

[0113] In order to optimize the optical performance of the optical system of Example 4, the thickness of the Fresnel lens is less than 6 mm, the absolute value of the radius of curvature of the side of the Fresnel lens with a serrated structure is less than 70 mm; the spatial interval between the convexo lens and the Fresnel lens is less than 5.5 mm, and the total length of the display module is less than 15 mm; 0.88<total length of the display module / focal length of the pancake display assembly<0.9.

[0114] In order to further optimize the optical performance of the optical system of Example 4, the refractive index n1 of the Fresnel lens is 1.96, the Abbe number is 17, the aperture is greater than 40 mm, the radius of curvature of the side surface of the Fresnel lens with a sawtooth structure is 64.1 mm, the radius of curvature of the convex surface of the Fresnel lens is 49.5 mm, and the thickness of the Fresnel lens is 2 mm;

[0115] The refractive index n2 of the convex-concave lens is 1.7, the Abbe number is 54, the aperture is greater than 40 mm, the curvature radius of the convex surface of the convex-concave lens is 56 mm, the curvature radius of the concave surface of the convex-concave lens is -714 mm, and the thickness of the convex-concave lens is 3 mm;

[0116] The space between the Fresnel lens and the convex-concave lens is 5.25 mm;

[0117] n1 and n2 satisfy: 1 <n1 / n2<1.1。

[0118] Tested and proven, reference Figure 6-8 As a result, the display module system using the folded pancake solution combined with the Fresnel lens of the present invention has good imaging quality. Figure 6 As shown, the MTF is greater than 0.3 at a frequency of 30lp / mm. MTF stands for modulation transfer function, and the horizontal axis of the MTF graph is the spatial frequency. From the MTF graph of the lens group, we can derive the contrast at any spatial frequency under the maximum spatial frequency that the lens can support. The MTF contrast of this embodiment is large, which means less information loss. Figure 7 , the field curvature of the embodiment of the present invention is less than 0.2 mm. Smaller field curvature means that the imaging is closer to the ideal state, that is, the entire image plane can obtain a clearer image, thereby improving the overall clarity and visual effect of the image. Figure 8 , the distortion of the embodiment of the present invention is about 19%, which means that the geometric shape and proportion of the image presented by the present invention can be well restored.

[0119] The optical machine of the present invention is light in weight, and has the effect of being thin and light with excellent image quality:

[0120] 1. Thinness and lightness: The pancake display component pancake solution effectively compresses the distance between the screen and the lens through the folded light path design, further shortens the total length of the optical module, and reduces the weight of the head display by more than 50%. In addition, combined with the Fresnel lens, the weight of the optical machine is further reduced by at least 50%.

[0121] 2. High image quality: Combined with the use of Fresnel lens, the image quality at the edge of the lens is improved, image distortion is reduced, and image contrast, clarity and fineness are improved.

[0122] 3. Adjustable diopter: The pancake solution supports diopter adjustment, which is friendly to myopic users and solves the VAC (visual convergence accommodation conflict) problem.

[0123] 4. Improved field of view: By optimizing the combination of pancake optical path design and Fresnel lens, the field of view can be expanded to more than 90° while maintaining lightness and thinness, thereby enhancing the user's immersive experience.

[0124] The display module of the present invention is not only applicable to the two-lens optical system in Examples 1-4, but can also be applied to a display module composed of three or more lenses.

[0125] In one embodiment, referred to as Embodiment 5, refer to Fig. 9 The display module of this embodiment differs from the display module of Embodiment 1 only in that:

[0126] Between the convex lens 1 (lens 1) and the Fresnel lens 2 (lens 2), there is a lens 3. The lens 3 is similar to the lens 1 and is also a lens 9 having a convex lens structure.

[0127] The film arrangement of Example 5 is similar to that of Example 1. The first phase retardation film 4 and the reflective polarizing film 5 are arranged on the lens adjacent to the light-emitting side of the pancake display assembly, i.e., lens 2 in this embodiment, and are located on the side of lens 2 having a sawtooth structure. The first phase retardation film 4 and the reflective polarizing film 5 face the light-emitting side of the pancake display assembly.

[0128] The semi-transmissive and semi-reflective film 6 is disposed on a lens adjacent to the light incident side of the pancake display assembly, namely, on the lens 1 in this embodiment, and the semi-transmissive and semi-reflective film 6 faces the light incident side of the pancake display assembly.

[0129] After adding lens 3 in embodiment 5, the number of lenses in the display module is increased, and the optical imaging quality is improved.

[0130] In one embodiment, referred to as Embodiment 6, refer to Fig.10The display module of this embodiment includes: a light-emitting component 3, two Fresnel lenses and two convex lenses. A first lens 10, a second lens 11, a third lens 12 and a fourth lens 13 are sequentially arranged in a direction away from the light-emitting component 3, wherein the first lens 10 and the third lens 12 are both convex lenses with double-sided aspherical surfaces, and the second lens 11 and the fourth lens 13 are Fresnel lenses. The second lens 11 has a sawtooth structure, which is arranged toward one side of the light-emitting component 3 and the other side is a curved surface. A semi-transparent and semi-reflective film 6 is arranged on one side of the second lens 11 having the sawtooth structure. The fourth lens 13 has a sawtooth structure, which is arranged toward one side of the light-emitting component 3 and the other side is a flat surface. The surface of the fourth lens 13 having the sawtooth structure is sequentially bonded with a first phase delay film 4 and a reflective polarizing film 5.

[0131] In this embodiment, multiple lenses can more effectively correct imaging deformation and distortion, and improve image clarity and realism. The present invention is based on a pancake folded optical path and is combined with a Fresnel lens to achieve a lighter and thinner entire optical system. In a multi-lens combination, the invention has more advantages because it maximizes the lightness and thinness.

[0132] The present invention also provides a head-mounted display device, comprising a head-mounted support component and the display module, wherein the display module is used to present images.

[0133] In one embodiment, the head-mounted support component includes a head-mounted support component of a common VR optical system. The display module of the present invention is based on a pancake folded optical path and is matched with a Fresnel lens to realize an ultra-short focus and lightweight optical system. Compared with a single pancake solution, the pancake of the present invention combined with a Fresnel lens can not only shorten the total length, but also increase the FOV and improve the imaging quality. The surface of the Fresnel lens with a serrated structure can be placed on any surface of any one of the multiple lenses in the display module, and can be a film material application surface or a semi-transparent and semi-reflective surface. The film material application can be achieved by in-mold injection molding to couple the Fresnel lens and the film material together, with high integration. The present invention can significantly reduce ghosting and improve visual effects.

[0134] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A display module, characterized in that: include: Light emitting components; a pancake display assembly, wherein a light incident side of the pancake display assembly is configured to receive light emitted by the light emitting assembly; The pancake display assembly includes a lens, a semi-transparent and semi-reflective film, a first phase delay film and a reflective polarizing film; wherein, there are multiple lenses, and the lenses include at least one Fresnel lens, the first phase delay film and the reflective polarizing film are stacked and arranged on any one of the multiple lenses in a direction away from the light-emitting assembly, and the semi-transparent and semi-reflective film is arranged on any one of the lenses between the display assembly and the stacked first phase delay film and the reflective polarizing film.

2. The module according to claim 1, characterized in that: There are two lenses, a convex lens and a Fresnel lens; The convex lens and the Fresnel lens are arranged in sequence along a direction away from the light-emitting component.

3. The module according to claim 2, characterized in that: One side of the Fresnel lens has a sawtooth structure, the sawtooth structure is arranged toward one side of the light-emitting component, the other side of the Fresnel lens is a plane, and a first phase delay film and a reflective polarizing film are arranged on the plane of the Fresnel lens; A semi-transparent and semi-reflective film is arranged on one side of the convex lens facing the light-emitting component.

4. The module according to claim 2, characterized in that: One side of the Fresnel lens has a sawtooth structure, the sawtooth structure is arranged toward the light-emitting side of the pancake display assembly, the other side of the Fresnel lens is an aspherical surface, and the side of the Fresnel lens having the sawtooth structure is provided with a first phase delay film and a reflective polarizing film; A semi-transparent and semi-reflective film is arranged on one side of the convex lens facing the light-emitting component.

5. The module according to claim 2, characterized in that: One side of the Fresnel lens has a sawtooth structure, the sawtooth structure is arranged toward one side of the light-emitting component, the other side of the Fresnel lens is an aspherical surface or a plane, and the aspherical surface or the plane of the Fresnel lens is provided with a first phase delay film and a reflective polarizing film; A semi-transparent and semi-reflective film is disposed on one side of the convex lens facing the light-emitting side of the display module.

6. The module according to any one of claims 2 to 5, characterized in that: The convex lens is an aspherical lens.

7. The module according to claim 6, characterized in that: 0.88<total length of display module / focal length of pancake display assembly<0.9, 14mm<total length of display module<15mm.

8. The module according to claim 1, characterized in that: There are two lenses, namely Fresnel lens and convex-concave lens; The Fresnel lens and the convex-concave lens are arranged in sequence in a direction away from the light-emitting component; One side of the Fresnel lens is a convex surface, the convex surface of the Fresnel lens is arranged toward one side of the light-emitting component, and the other side of the Fresnel lens has a sawtooth structure; a semi-transparent and semi-reflective film is arranged on the convex surface of the Fresnel lens; One side of the convex-concave lens is a concave surface, which is arranged toward one side of the light-emitting component, and the other side is a convex surface. A first phase delay film and a reflective polarizing film are arranged on the convex surface of the convex-concave lens.

9. The module according to claim 8, characterized in that: The thickness of the Fresnel lens is less than 6 mm, and the absolute value of the radius of curvature of the side of the Fresnel lens with a serrated structure is less than 70 mm; the space between the convexo lens and the Fresnel lens is less than 5.5 mm, and the total length of the display module is less than 15 mm; 0.88<total length of the display module / focal length of the pancake display assembly<0.

9.

10. The module according to claim 9, characterized in that: The refractive index n1 of the Fresnel lens is 1.96, the Abbe number is 17, the aperture is greater than 40 mm, the curvature radius of the side surface of the Fresnel lens with a sawtooth structure is 64.1 mm, the curvature radius of the convex surface of the Fresnel lens is 49.5 mm, and the thickness of the Fresnel lens is 2 mm; The refractive index n2 of the convex-concave lens is 1.7, the Abbe number is 54, the aperture is greater than 40 mm, the curvature radius of the convex surface of the convex-concave lens is 56 mm, the curvature radius of the concave surface of the convex-concave lens is -714 mm, and the thickness of the convex-concave lens is 3 mm; The space between the Fresnel lens and the convex-concave lens is 5.25 mm; n1 and n2 satisfy: 1 <n1 / n2<1.1。 11. The module according to claim 1, characterized in that: The light emitting component comprises: A light emitting element, used for emitting light; The dimming element is used to adjust the optical form of the light emitted by the light-emitting element so that the emitted light of the light-emitting component is circularly polarized light.

12. The module according to claim 11, characterized in that: The dimming element comprises: Polarizer and second phase retardation film; Wherein, on a side close to the pancake display assembly, along a direction away from the light-emitting element, the polarizer and the second phase delay film are arranged in sequence.

13. The module according to claim 12, characterized in that: The second phase delay film is a quarter wave plate, and the first phase delay film is a quarter wave plate.

14. The module according to claim 1, characterized in that: The first phase delay film and the reflective polarizing film are integrally formed with or bonded to any one of the plurality of lenses.

15. The module according to claim 1, characterized in that: There are more than three lenses, and the first phase delay film and the reflective polarizing film are arranged on the lens adjacent to the light-emitting side of the pancake display assembly, and the first phase delay film and the reflective polarizing film face the light-emitting side of the pancake display assembly.

16. The module according to claim 1 or 15, characterized in that: There are more than three lenses, and the semi-transparent and semi-reflective film is arranged on the lens adjacent to the light-entering side of the pancake display component, and the semi-transparent and semi-reflective film faces the light-entering side of the pancake display component.

17. A head mounted display device, characterized in that: It comprises a head-mounted support component and a display module as described in any one of claims 1 to 16, and the display module is used to present images.

Images