CN115963642A - Fresnel lens and virtual reality display device - Google Patents

Abstract

The embodiment of the application provides a fresnel lens and virtual reality display device, wherein, fresnel lens includes: a lens body; the lens comprises a lens body, a plurality of annular bulges, a plurality of lens grooves and a plurality of connecting surfaces, wherein the plurality of annular bulges are arranged on one side of the lens body along the radial direction of the lens body; the light-transmitting substrate is located on one side, away from the lens body, of the annular protrusions, a plurality of shading units are arranged on one side, facing the lens body, of the light-transmitting substrate, wherein orthographic projections of the shading units on the projection surface cover orthographic projections of the corresponding connecting surfaces on the projection surface, and the projection surface is perpendicular to an optical axis of the Fresnel lens. According to the technical scheme, stray light emitted by the Fresnel lens can be reduced, and the imaging quality of the Fresnel lens is improved.

Description

Fresnel lens and virtual reality display device

Technical Field

The application relates to the technical field of display, in particular to a Fresnel lens and a virtual reality display device.

Background

In the related art, a through type aspherical lens group and a return type lens group may be employed in a virtual reality display device. The straight-through aspheric lens group has high luminous efficiency which can reach more than 80%, but has thick thickness which is generally more than 35 mm; the thickness of the folding lens group is thin and can reach below 30mm, but the light efficiency is low and is generally less than 25%. In order to achieve the effects of high luminous efficiency and thin thickness, a fresnel lens group is often adopted, however, the fresnel lens easily generates stray light to affect the display effect, thereby reducing the experience of viewers.

Disclosure of Invention

The embodiment of the application provides a Fresnel lens and a virtual reality display device, and aims to solve or relieve one or more technical problems in the prior art.

As an aspect of the embodiments of the present application, an embodiment of the present application provides a fresnel lens, including: a lens body; the lens comprises a lens body, a plurality of annular bulges, a plurality of lens grooves and a plurality of lens grooves, wherein the plurality of annular bulges are arranged along the radial direction of the lens body; the light-transmitting substrate is located on one side, away from the lens body, of the annular protrusions, a plurality of shading units are arranged on one side, facing the lens body, of the light-transmitting substrate, wherein orthographic projections of the shading units on the projection surface cover orthographic projections of the corresponding connecting surfaces on the projection surface, and the projection surface is perpendicular to an optical axis of the Fresnel lens.

In one embodiment, the fresnel lens further comprises: the annular supporting part sets up in same one side of lens body with a plurality of annular archs, and the annular supporting part is located the bellied periphery of a plurality of annular, is formed with annular groove on the annular supporting part, and annular groove runs through annular supporting part and deviates from the one end terminal surface of lens body and the inner peripheral surface of annular supporting part, and the edge support of printing opacity base plate is in annular groove's diapire.

In one embodiment, a difference between a maximum diameter of the annular groove and a diameter of the light-transmitting substrate is 0.8 μm or less.

In one embodiment, the annular groove has a dimension of 0.5mm to 0.8mm in a direction parallel to the optical axis of the fresnel lens.

In one embodiment, one of the annular supporting portion and the transparent substrate is provided with a positioning column, the other of the annular supporting portion and the transparent substrate is provided with a positioning hole, and the positioning column is arranged in the positioning hole.

In one embodiment, the size of the positioning column is matched with that of the positioning hole, and the diameter of the positioning hole is less than or equal to 5 microns.

In one embodiment, the positioning columns and the positioning holes are multiple, the positioning columns are arranged at intervals along the circumferential direction of the lens body, and the positioning columns are arranged in the positioning holes in a one-to-one correspondence manner.

In one embodiment, the ratio of the dimension of the light shielding unit in the radial direction of the light-transmitting substrate to the radius of the corresponding connecting surface is 1 to 1.6.

As another aspect of the embodiments of the present application, an embodiment of the present application provides a virtual reality display apparatus, including: a display module; the optical module is arranged on one side of the display module and comprises the Fresnel lens of any one of the above embodiments.

In one embodiment, the light-transmitting substrate of the fresnel lens faces the display module.

In one embodiment, in the direction toward the display module, the optical module includes a first lens, a second lens, a third lens and a fourth lens, which are sequentially disposed along the same optical axis, wherein the first lens, the second lens and the third lens are fresnel lenses, and the fourth lens is an aspheric lens; or the first lens and the second lens are Fresnel lenses, and the third lens and the fourth lens are aspheric lenses.

In one embodiment, the angle of view of the optical module is 90 °, and the distance between the surface of the first lens facing away from the display module and the display module is less than or equal to 30mm along the optical axis direction of the optical module.

The embodiment of the application adopts above-mentioned technical scheme can effectively reduce the light yield of the bellied invalid side of annular to reduce the stray light of fresnel lens outgoing, and then promote fresnel lens's imaging quality, under fresnel lens was applied to virtual reality display device's the condition, can effectively promote the experience of viewer using virtual reality display device in-process and feel.

The foregoing summary is provided for the purpose of description only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features of the present application will be readily apparent by reference to the drawings and following detailed description.

Drawings

In the drawings, like reference characters designate like or similar parts or elements throughout the several views unless otherwise specified. The figures are not necessarily to scale. It is appreciated that these drawings depict only some embodiments in accordance with the disclosure and are therefore not to be considered limiting of its scope.

Fig. 1 shows a schematic structural view of a conventional lens.

Fig. 2 is a schematic diagram illustrating a structure of a fresnel lens in the related art.

Fig. 3 to 5 are schematic diagrams illustrating imaging of a fresnel lens in the related art.

Fig. 6 shows a schematic structural diagram of a fresnel lens according to an embodiment of the present application.

Fig. 7 is a schematic cross-sectional view illustrating an annular projection of a fresnel lens and a light shielding unit according to an embodiment of the present application.

Fig. 8 and 9 show imaging schematic diagrams of fresnel lenses according to embodiments of the present application.

Fig. 10 shows a schematic diagram of an explosion structure of a fresnel lens according to an embodiment of the present application.

Fig. 11 shows a schematic diagram of an exploded structure of a fresnel lens according to another embodiment of the present application.

Fig. 12 shows a schematic diagram of an exploded structure of a fresnel lens according to yet another embodiment of the present application.

Fig. 13 is a schematic structural diagram of a virtual reality display device according to an embodiment of the present application.

FIG. 14 illustrates a graph of the modulation transfer function of the optical module of the virtual reality display device shown in FIG. 13.

Fig. 15 is a schematic structural diagram of a virtual reality display device according to another embodiment of the present application.

FIG. 16 shows a graph of the modulation transfer function of the optical module of the virtual reality display device shown in FIG. 15.

Description of reference numerals:

the related technology comprises the following steps: 1: a conventional lens; 2: a Fresnel lens; 21: saw-toothed protrusions;

the application: 100: a Fresnel lens;

110: a lens body; 120: an annular projection; 121: an effective surface; 122: an invalid face; 123: a connecting surface; 130: a light-transmitting substrate; 140: a light shielding unit; 150: an annular support portion; 160: an annular groove; 170: a positioning column; 180: positioning holes;

200: a virtual reality display device;

210: a display module; 220: an optical module; 221: a first lens; 222: a second lens; 223: a third lens; 224: and a fourth lens.

Detailed Description

In the following, only certain exemplary embodiments are briefly described. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present application. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.

Near-to-eye display technologies using Virtual Reality (VR) and Augmented Reality (AR) as main application scenes are becoming more and more important ways for people to acquire information. Currently, the mainstream near-eye display optical technology mainly includes: waveguide display, free-form surface display, integrated imaging optical field display and the like. Wherein the waveguide exhibits sensitivity to incident light wavelengths, and is highly susceptible to dispersion; the waveguide optical coupling structure also has a dispersion effect on external light, and ghost images and other phenomena can occur in the wearing process. The overall size of the free-form surface display scheme is large, and the large field angle and the device size are difficult to balance; the integrated imaging light field display is difficult to realize the permeation of external light, and the augmented reality display effect is poor. In the imaging optical system, one or more images similar to the image point exist near the image point, and the image points other than the image point are collectively called "ghost image", which is a kind of light spot.

In the virtual reality display technology, a display picture presented by a display panel is imaged to a position 25 mm to 50 mm in front of human eyes or a position closer to the human eyes by adopting a lens, and different pictures are seen by the left and right eyes of a person respectively, so that a stereoscopic impression can be generated after brain processing, and a viewer has a feeling of being personally on the scene.

In the related art, a through type aspheric lens group and a return type lens group may be adopted in the virtual reality display device. The through-type aspheric lens group has the advantages of low design and processing difficulty, high lighting effect, no stray light and the like, but is thick and not beneficial to realizing the lightness and thinness of products. The foldback lens group has the advantages of better imaging quality and thinner thickness, but the light efficiency is lower, and the phenomena of ghost shadow and the like exist. The Fresnel lens group is expected to have the advantages of high light efficiency of the straight-through aspheric lens group and thin thickness of the turn-back lens group. However, the fresnel lens is prone to generate stray light, which affects the display effect.

Fig. 1 shows a schematic structural view of a conventional lens 1; fig. 2 shows a schematic structural diagram of a fresnel lens 2 in the related art. Since the refraction of light only occurs at the surface of the lens, the fresnel lens 2 is formed by only preserving the curvature of the surface if the lens is removed as much as possible of the optical material, so that the fresnel lens 2 can be reduced in weight and thickness as compared with the conventional lens 1. One side of the fresnel lens 2 is typically provided with a plurality of serrations 21. In practical applications, the widths w of the plurality of serrations 21 may be equal to form a fresnel lens 2 of equal width; alternatively, the heights h of the plurality of serrations 21 may be equal to form the fresnel lens 2 of equal tooth height.

Simulation tests and experimental results show that the apex angle of the serrations 21 has the greatest effect on the amount of stray light formed by the fresnel lens 2. Fig. 3 to 5 are schematic diagrams illustrating imaging of a fresnel lens in the related art. As shown in fig. 3 to 5, the black area is a background, the white area is an imaging schematic diagram, when bright light passes through the fresnel lens 2, a part of the light is reflected or refracted by the ineffective surface of the saw-tooth protrusion 21 to form stray light, and finally glare is formed during imaging to blur the edge of the image, so that the imaging quality of the fresnel lens 2 is poor, and the experience of a viewer in using the virtual reality display device is poor.

A fresnel lens 100 according to an embodiment of the first aspect of the present application is described below with reference to fig. 6 to 12.

FIG. 6 illustrates a schematic structure diagram of a Fresnel lens 100 according to an embodiment of the present application; fig. 7 is a schematic cross-sectional view illustrating the annular protrusion of the fresnel lens 100 and the light shielding unit 140 according to an embodiment of the present application. As shown in fig. 6 and 7, the fresnel lens 100 includes a lens body 110, a plurality of annular protrusions 120, and a light-transmitting substrate 130. In the description of the present application, "a plurality" means two or more.

Specifically, a plurality of annular protrusions 120 are disposed on one side of the lens body 110, the plurality of annular protrusions 120 are arranged in a radial direction of the lens body 110, each annular protrusion 120 has an effective surface 121, an ineffective surface 122, and a connection surface 123, and the connection surface 123 is connected between the effective surface 121 and the ineffective surface 122. The "effective surface" can be understood as an imaging effective surface, and light refracted by the effective surface can finally form a visual virtual image on human eyes; the "non-effective surface" can be understood as an imaging non-effective surface, and light formed by reflection or refraction through the non-effective surface is stray light which can influence the final display effect and reduce the imaging quality.

The light-transmitting substrate 130 is located on a side of the annular protrusions 120 away from the lens body 110, and a plurality of light-shielding units 140 are disposed on a side of the light-transmitting substrate 130 facing the lens body 110, wherein an orthogonal projection of each light-shielding unit 140 on a projection plane covers an orthogonal projection of the corresponding connection surface 123 on the projection plane, and the projection plane is perpendicular to the optical axis of the fresnel lens 100.

Illustratively, the light-transmitting substrate 130 may be a glass substrate. The light shielding unit 140 may be a light shielding pattern prepared on the light transmissive substrate 130, and the material of the light shielding unit 140 may be a light shielding resin material, or the like. When preparing, it is possible to ensure that the plurality of light shielding units 140 correspond to the plurality of annular protrusions 120 one-to-one by corresponding the coordinates of the light shielding units 140 to the coordinates of the connection surfaces 123 one-to-one.

Illustratively, the lens body 110 has a first side and a second side, and the first side may be disposed toward the light source. The first side is provided with a plurality of annular protrusions 120, and the plurality of annular protrusions 120 may form a plurality of concentric circular ring structures. The second side can be a light-emitting side, and the surface of the second side can be a spherical surface or an aspheric surface. When the light is emitted to the fresnel lens 100, a portion of the light may be emitted to the first side of the lens body 110 through the transparent substrate 130, and the portion of the light may be incident to the fresnel lens 100 from the effective surface 121 of the annular protrusion 120, and is refracted once in the annular protrusion 120, so as to achieve the converging effect of the portion of the light, and finally exits from the light exit side to enter the human eye. Another portion of the light can be blocked or absorbed by the light blocking unit 140, so as to avoid the light from being incident on the connecting surface 123 of the annular protrusion 120. Fig. 8 and 9 show imaging diagrams of the fresnel lens 100 according to an embodiment of the present application. With reference to fig. 8 and 9, the black area is a background, and the white area is an imaging schematic diagram, compared with the related art, the image of the fresnel lens 100 in the embodiment of the present application is clearer, so that the glare amount of blurring the edge of the image is significantly reduced, and a part of light can be prevented from being emitted from the inactive surface 122 after being incident from the connecting surface 123, thereby reducing stray light emitted from the inactive surface 122, improving glare of the fresnel lens 100, and effectively improving imaging quality.

For example, the orthographic projection of each light shielding unit 140 on the projection surface may also cover the orthographic projection of the corresponding ineffective surface 122 on the projection surface, but is not limited thereto.

According to the fresnel lens 100 of the embodiment of the application, the light-transmitting substrate 130 is disposed on one side of the plurality of annular protrusions 120 away from the lens body 110, and the plurality of light-shielding units 140 in one-to-one correspondence with the plurality of annular protrusions 120 are disposed on one side of the light-transmitting substrate 130 facing the lens body 110, so that the light-emitting amount of the inactive surface 122 of the annular protrusion 120 can be effectively reduced, thereby reducing stray light emitted from the fresnel lens 100, and further improving the imaging quality of the fresnel lens 100, and in a case that the fresnel lens 100 is applied to the virtual reality display device 200, the experience of a viewer in using the virtual reality display device 200 can be effectively improved.

Fig. 10 shows an exploded view of a fresnel lens 100 according to an embodiment of the present application. In an embodiment, as shown in fig. 6, 7 and 10, the fresnel lens 100 further includes an annular support portion 150, the annular support portion 150 and the plurality of annular protrusions 120 are disposed on the same side of the lens body 110, the annular support portion 150 is located at the outer periphery of the plurality of annular protrusions 120, an annular groove 160 is formed on the annular support portion 150, the annular groove 160 penetrates through an end surface of the annular support portion 150 facing away from the lens body 110 and an inner peripheral surface of the annular support portion 150, and an edge of the transparent substrate 130 is supported on a bottom wall of the annular groove 160. The inner wall of the annular groove 160 perpendicular to the optical axis of the fresnel lens 100 is a bottom wall, and the inner wall connected to the bottom wall is a side wall.

Illustratively, the annular groove 160 has a bottom wall and a side wall. A stepped portion may be formed between the bottom wall and the side wall of the annular groove 160. When mounting, the transparent substrate 130 may be placed in the annular groove 160, such that the edge of the transparent substrate 130 contacts the bottom wall of the annular groove 160, and the middle portion of the transparent substrate 130 is opposite to the plurality of annular protrusions 120. The light-shielding units 140 are disposed at intervals in the middle of the transparent substrate 130, and each light-shielding unit 140 is directly opposite to the corresponding annular protrusion 120. The annular supporting portion 150 may be provided with a dispensing slot, and after the transparent substrate 130 is placed in the annular groove 160, the transparent substrate 130 and the annular supporting portion 150 may be dispensed and fixed at the dispensing slot. Wherein, a side surface of the transparent substrate facing away from the annular protrusion 120 may be substantially flush with an end surface of the annular support portion 150 facing away from the lens body 110.

In this embodiment, the edge of the transparent substrate 130 is supported on the bottom wall of the annular groove 160, so that the transparent substrate 130 can be supported and fixed, and the structure of the fresnel lens 100 is more stable and reliable. Moreover, the side wall of the annular groove 160 can effectively stop and limit the transparent substrate 130, so that the transparent substrate 130 can be prevented from shifting, the light shielding unit 140 on the transparent substrate 130 can accurately shield the connecting surface 123, and the glare of the fresnel lens 100 can be effectively improved.

In one embodiment, the difference between the maximum diameter of the annular groove 160 and the diameter of the light-transmitting substrate 130 is 0.8 μm or less. So set up, when guaranteeing that printing opacity base plate 130 can put into annular groove 160, can effectively inject printing opacity base plate 130 at its ascending removal in footpath, realize printing opacity base plate 130's location to guarantee that shading unit 140 on the printing opacity base plate 130 can just right with the annular arch 120 that corresponds, carry out the accuracy to the connection face 123 of annular arch 120 and shelter from, and the processing degree of difficulty is lower.

In one embodiment, the size of the annular groove 160 is 0.5mm to 0.8mm (inclusive) in a direction parallel to the optical axis of the fresnel lens 100, i.e., the height of the annular groove 160 is 0.5mm to 0.8mm. Specifically, for example, when the height of the annular groove 160 is less than 0.5mm, the height of the annular groove 160 is too small, which may cause the transparent substrate 130 to protrude from the end surface of the annular support 150 to be too large, such that the sidewall of the annular groove 160 cannot function as an effective stop. When the height of the annular groove 160 is greater than 0.8mm, the height of the annular groove 160 is excessively large, which may cause the height of the annular support 150 to be excessively large, thereby increasing the thickness of the entire fresnel lens 100.

Therefore, through the above arrangement, the size of the annular groove 160 is reasonable, the movement of the light-transmitting substrate 130 in the radial direction thereof is effectively limited, and meanwhile, the thickness of the fresnel lens 100 can be reduced, so that the light and thin design of the virtual reality display device 200 is facilitated when the fresnel lens 100 is applied to the virtual reality display device 200.

Fig. 11 shows a schematic diagram of an exploded structure of a fresnel lens 100 according to another embodiment of the present application; fig. 12 shows a schematic diagram of an explosion structure of a fresnel lens 100 according to yet another embodiment of the present application. As shown in fig. 11 and 12, in one embodiment, one of the annular supporting portion 150 and the transparent substrate 130 is provided with a positioning post 170, the other of the annular supporting portion 150 and the transparent substrate 130 is provided with a positioning hole 180, and the positioning post 170 is disposed in the positioning hole 180.

In one example, referring to fig. 11, the annular supporting portion 150 is provided with a positioning post 170, and the transparent substrate 130 is formed with a positioning hole 180. For example, the positioning posts 170 may be disposed on the bottom wall of the annular groove 160, the positioning holes 180 are disposed on the edge of the transparent substrate 130, and the positioning holes 180 penetrate through the transparent substrate 130 along the thickness direction of the transparent substrate 130. The height of the positioning column 170 may be equal to the thickness of the transparent substrate 130. After the installation, the positioning column 170 is fitted in the positioning hole 180, and a side surface of the transparent substrate 130 facing the annular protrusion 120 contacts with the bottom wall of the annular groove 160, and an end surface of the positioning column 170 facing away from the lens body 110 may be flush with a side surface of the transparent substrate 130 facing away from the lens body 110.

In another example, as shown in fig. 12, the transparent substrate 130 is provided with a positioning column 170, and the annular supporting portion 150 is formed with a positioning hole 180. For example, the positioning column 170 and the light shielding unit 140 may be disposed on the same side of the transparent substrate 130, and the positioning hole 180 may be formed by the bottom wall of the annular groove 160 being recessed toward the lens body 110. The depth of the positioning hole 180 may be equal to the height of the positioning post 170.

In this embodiment, by providing the positioning column 170 and the positioning hole 180, the light-transmitting substrate 130 can be accurately positioned, and the light-shielding unit 140 on the light-transmitting substrate 130 can be further ensured to be aligned with the corresponding annular protrusion 120, so as to accurately shield the connecting surface 123 of the annular protrusion 120, thereby improving the glare of the fresnel lens 100.

In one embodiment, the positioning post 170 has a size corresponding to that of the positioning hole 180, and the diameter of the positioning hole 180 is less than or equal to 5 μm. Illustratively, the diameter of the positioning post 170 may be equal to the diameter of the positioning hole 180, or the diameter of the positioning post 170 may be slightly smaller than the diameter of the positioning hole 180. The shape of the positioning post 170 can be matched with the shape of the positioning hole 180. After the positioning column 170 is fitted in the positioning hole 180, the outer circumferential surface of the positioning column 170 can be attached to the inner wall surface of the positioning hole 180, so that relative movement of the positioning column 170 and the positioning hole 180 in the radial direction is effectively limited.

Therefore, the size of the positioning column 170 is matched with that of the positioning hole 180, so that accurate positioning of the light-transmitting substrate 130 can be further ensured, and the light-shielding unit 140 on the light-transmitting substrate 130 can effectively shield the connecting surface 123 of the annular protrusion 120, thereby reducing stray light emitted by the Fresnel lens 100 and improving the imaging quality of the Fresnel lens 100. By making the diameter of the positioning hole 180 less than or equal to 5 μm, the size of the positioning hole 180 is relatively small, thereby avoiding affecting the structural strength of the corresponding annular supporting portion 150 or the transparent substrate 130.

In an embodiment, referring to fig. 11 and 12, a plurality of positioning pillars 170 and positioning holes 180 are provided, the positioning pillars 170 are disposed at intervals along the circumferential direction of the lens body 110, and the positioning pillars 170 are disposed in the positioning holes 180 in a one-to-one correspondence. For example, the positioning posts 170 may be uniformly spaced along the circumferential direction of the lens body 110, and the number of the positioning posts 170 and the number of the positioning holes 180 may be greater than or equal to 3. Therefore, the positioning accuracy and reliability can be further improved by the positioning columns 170 and the positioning holes 180, the shading unit 140 can be opposite to the corresponding annular protrusions 120, and the reliability is higher.

In one embodiment, referring to fig. 6 and 7, the ratio of the dimension L of the light shielding unit 140 in the radial direction of the transparent substrate 130 to the radius R of the corresponding connection surface 123 is 1 to 1.6 (inclusive). For example, L/R may be 1.5. Specifically, for example, when L/R is smaller than 1, the width of the light shielding unit 140 is too small to effectively prevent light from entering from the connecting surface 123 and then exiting from the ineffective surface 122, so that the amount of light exiting from the ineffective surface 122 of the annular protrusion 120 is too large, and a large amount of stray light is easily generated. In the case where L/R > 1.6, the width of the light shielding unit 140 is too large, which may cause the light shielding unit 140 to shield the effective surface 121, which is not favorable for image formation. Alternatively, the radius R of the connecting surface 123 may be less than 30 μm, but is not limited thereto.

Therefore, by setting the L/R to 1 to 1.6, the width of the light shielding unit 140 is reasonable, and the imaging effect of the fresnel lens 100 can be ensured on the premise of effectively reducing the light output amount of the ineffective surface 122 of the annular protrusion 120.

A virtual reality display apparatus 200 according to an embodiment of the second aspect of the present application is described below with reference to fig. 6, 13 to 16.

Fig. 13 is a schematic structural diagram of a virtual reality display apparatus 200 according to an embodiment of the present application. As shown in fig. 13, the virtual reality display apparatus 200 includes a display module 210 and an optical module 220. The optical module 220 is disposed on one side of the display module 210, and the optical module 220 includes the fresnel lens 100 according to any of the above-mentioned first embodiments of the present disclosure.

According to the virtual reality display device 200 of the embodiment of the application, by adopting the fresnel lens 100, the light weight, thinness and high light efficiency of a product can be realized, for example, the light efficiency of the product can be more than 50%, outgoing stray light can be reduced, and the experience of a viewer in the process of using the virtual reality display device 200 can be effectively improved.

In one embodiment, as shown in fig. 13, the transparent substrate 130 of the fresnel lens 100 is disposed facing the display module 210. For example, the optical module 220 may include a plurality of fresnel lenses 100, and the transparent substrate 130, which may be one of the fresnel lenses 100 farthest away from the display module 210, is disposed facing the display module 210; alternatively, the transparent substrates 130 of the fresnel lenses 100 are all disposed facing the display module 210. In this way, impurities such as external dust can be prevented from falling into the annular protrusion 120, and the imaging quality of the fresnel lens 100 can be ensured, so that the display effect of the virtual reality display device 200 is improved.

In one embodiment, referring to fig. 13, the optical module 220 includes a first lens 221, a second lens 222, a third lens 223 and a fourth lens 224, which are sequentially disposed along the optical axis in a direction toward the display module 210, wherein the first lens 221, the second lens 222 and the third lens 223 are the fresnel lens 100, and the fourth lens 224 is an aspheric lens. For example, in the example of fig. 13, the optical module 220 includes three fresnel surfaces. The transparent substrate 130 of the first lens 221, the second lens 222 and the third lens 223 are disposed facing the display module 210. The optical module 220 is a straight-through optical scheme as a whole.

Of course, the present application is not limited thereto. Fig. 15 shows a schematic structural diagram of a virtual reality display apparatus 200 according to another embodiment of the present application. In another embodiment, as shown in fig. 15, the first lens 221 and the second lens 222 are fresnel lenses 100, and the third lens 223 and the fourth lens 224 are aspheric lenses. For example, in the example of fig. 15, the optical module 220 includes two fresnel surfaces. The transparent substrate 130 of the first lens 221 and the second lens 222 are disposed facing the display module 210. The optical module 220 is a straight-through optical solution as a whole.

FIG. 14 illustrates a graph of the modulation transfer function of optical module 220 of virtual reality display device 200 shown in FIG. 13; fig. 16 shows a graph of the modulation transfer function of optical module 220 of virtual reality display device 200 shown in fig. 15. Wherein, the horizontal axis is spatial frequency, the unit is line pair/millimeter (lp/mm), and the line logarithm which can be resolved per millimeter is the numerical value of resolution; the vertical axis represents the Modulation Transfer Function (MTF) which is a quantitative description of the resolution of the lens, and represents the magnitude of the contrast, and the smaller the Modulation degree, the smaller the contrast is, and the Modulation degree is 0 if the contrast disappears completely. As shown in fig. 14 and 16, in the field of view of the optical module 220 in this embodiment, the MTF value of the field of view 0 (i.e., the central field of view) may reach 1, and the MTF value of most curves may be greater than 0.1, so that the optical module 200 has a higher imaging quality.

The field of view (FOV) of the optical module 220 is 90 °, and a distance between a surface of the first lens 221 facing away from the display module 210 and the display module 210 is less than or equal to 30mm along the optical axis of the optical module 220. That is, the total optical length of the virtual reality display apparatus 200 may be 30mm or less. Accordingly, the virtual reality display apparatus 200 can realize a large field angle and a light and thin design on the premise of having high light efficiency and high image quality, thereby improving the overall performance of the virtual reality display apparatus 200.

Other configurations of the fresnel lens 100 and the virtual reality display device 200 of the above embodiments can be adopted by various technical solutions known to those skilled in the art now and in the future, and will not be described in detail here.

In the description of the present specification, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the present application and to simplify the description, and are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be considered limiting of the present application.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

In this application, unless expressly stated or limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly and encompass, for example, both fixed and removable connections or integral parts thereof; the connection can be mechanical connection, electrical connection or communication; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as appropriate.

In this application, unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may comprise direct contact of the first and second features, or may comprise contact of the first and second features not directly but through another feature in between. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly above and obliquely above the second feature, or simply meaning that the first feature is at a lesser level than the second feature.

The above disclosure provides many different embodiments or examples for implementing different structures of the application. The components and arrangements of specific examples are described above to simplify the present disclosure. Of course, they are merely examples and are not intended to limit the present application. Moreover, the present application may repeat reference numerals and/or letters in the various examples, such repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive various changes or substitutions within the technical scope of the present application, and these should be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims (12)

1. A fresnel lens, comprising:

a lens body;

the lens comprises a lens body, a plurality of annular bulges and a plurality of connecting surfaces, wherein the plurality of annular bulges are arranged at one side of the lens body and are arranged along the radial direction of the lens body;

the light-transmitting substrate is positioned on one side, away from the lens body, of the annular protrusions, a plurality of shading units are arranged on one side, facing the lens body, of the light-transmitting substrate, wherein orthographic projections of the shading units on a projection surface cover orthographic projections of corresponding connection surfaces on the projection surface, and the projection surface is perpendicular to the optical axis of the Fresnel lens.

2. The fresnel lens according to claim 1, further comprising:

the annular supporting part is arranged on the same side of the lens body as the annular bulges, is positioned on the periphery of the annular bulges, is provided with an annular groove, penetrates through one end face of the annular supporting part, which deviates from the lens body, and the inner peripheral surface of the annular supporting part, and is supported on the bottom wall of the annular groove at the edge of the light-transmitting substrate.

3. The fresnel lens according to claim 2, wherein a difference between a maximum diameter of the annular groove and a diameter of the light-transmitting substrate is 0.8 μm or less.

4. The fresnel lens according to claim 2, wherein the size of the annular groove is 0.5mm to 0.8mm in a direction parallel to the optical axis of the fresnel lens.

5. The fresnel lens according to claim 2, wherein one of the annular support portion and the transparent substrate is provided with a positioning post, and the other of the annular support portion and the transparent substrate is provided with a positioning hole, and the positioning post is disposed in the positioning hole.

6. The Fresnel lens according to claim 5, wherein the positioning posts have a size corresponding to a size of the positioning holes, and a diameter of the positioning holes is 5 μm or less.

7. The Fresnel lens according to claim 5, wherein the positioning posts and the positioning holes are plural, the plural positioning posts are arranged at intervals along a circumferential direction of the lens body, and the plural positioning posts are arranged in the plural positioning holes in a one-to-one correspondence.

8. Fresnel lens according to one of the claims 1 to 7, characterised in that the ratio of the dimension of the shading unit in the radial direction of the light-transmitting substrate to the radius of the corresponding connecting surface is between 1 and 1.6.

9. A virtual reality display apparatus, comprising:

a display module;

an optical module disposed on one side of the display module, comprising the Fresnel lens according to any one of claims 1 to 8.

10. The virtual reality display device of claim 9, wherein the light-transmissive substrate of the fresnel lens is disposed facing the display module.

11. The virtual reality display device of claim 9, wherein the optical module comprises a first lens, a second lens, a third lens and a fourth lens which are arranged in sequence along the same optical axis along the direction towards the display module, wherein the first lens, the second lens and the third lens are fresnel lenses, and the fourth lens is an aspheric lens; or the first lens and the second lens are Fresnel lenses, and the third lens and the fourth lens are aspheric lenses.

12. The virtual reality display device of claim 11, wherein the optical module has a field angle of 90 °, and a distance between a surface of the first lens facing away from the display module and the display module is less than or equal to 30mm along an optical axis of the optical module.

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