WO2023226734A1

WO2023226734A1 - Fresnel lens group and virtual reality device

Info

Publication number: WO2023226734A1
Application number: PCT/CN2023/092665
Authority: WO
Inventors: 黄海涛; 陈丽莉; 韩娜
Original assignee: 京东方科技集团股份有限公司
Priority date: 2022-05-23
Filing date: 2023-05-08
Publication date: 2023-11-30
Also published as: CN114859450A; WO2023226653A1; CN117460973A

Abstract

The present application belongs to the technical field of display. Disclosed are a Fresnel lens group and a virtual reality device. The Fresnel lens group comprises a first Fresnel lens and a light blocking unit. The light blocking unit comprises a light blocking pattern, the first Fresnel lens is provided with a plurality of vertex angles, and the light blocking pattern and at least some of the plurality of vertex angles overlap in a direction parallel to an optical axis of the first Fresnel lens, so that the light emitting amount of an inactive surface of the first Fresnel lens can be reduced, and thus stray light emitted from the first Fresnel lens can be reduced. Therefore, the present application can solve the problem of poor imaging quality of Fresnel lens groups in the relevant art, and can improve the imaging quality of the Fresnel lens groups.

Description

Fresnel lens group and virtual reality device

This application claims priority to the Chinese patent application with application number 202210564712.0 and the invention name "Fresnel lens group and virtual reality device" submitted on May 23, 2022, the entire content of which is incorporated into this application by reference.

Technical field

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

Background technique

At present, with the development of virtual reality technology, there are more and more forms and types of virtual reality devices, and their application fields are becoming wider and wider. Virtual reality technology builds a virtual environment and displays information to users through the virtual environment. The virtual reality device outputs the image displayed by the display component (such as the display screen) in the device to the human eye through the transmission and amplification of the optical system. , what the human eye receives is an enlarged virtual image.

A Fresnel lens group used in a virtual reality device. The Fresnel lens group includes a Fresnel lens. Compared with an ordinary lens, the Fresnel lens can reduce the weight and thickness of the lens, so that the Fresnel lens can The lens group is thinner and lighter.

However, the Fresnel lens in the above-mentioned Fresnel lens group is more likely to generate stray light, resulting in poor imaging quality of the Fresnel lens group.

Contents of the invention

Embodiments of the present application provide a Fresnel lens group and a virtual reality device. The technical solutions are as follows:

According to a first aspect of the present application, a Fresnel lens group is provided, which includes: a first Fresnel lens and a light blocking unit;

One side of the first Fresnel lens has a sawtooth structure, the sawtooth structure includes a plurality of protrusions, and the protrusions have a vertex angle;

The light blocking unit is located outside the side of the first Fresnel lens with the zigzag structure. The light blocking unit includes a transparent base and a light blocking pattern located on the transparent base. The light blocking unit The orthographic projection of the pattern on the first plane overlaps with the orthographic projection of at least part of the plurality of vertex angles on the first plane, and the first plane is perpendicular to the first Fresnel The plane of the optical axis of the lens.

Optionally, the first Fresnel lens has a first area and a second area located at the periphery of the first area;

The orthographic projection of the light blocking pattern on the first plane is located within the orthographic projection of the second area on the first plane.

Optionally, a first ratio of the size of the second area in the first direction to the size of the first Fresnel lens in the first direction satisfies the following formula:
T＝1-2×P×tanθ/D

Wherein, T is the first ratio, P is the distance between the light incident surface of the first Fresnel lens and the viewer’s eyes, and D is the position of the first Fresnel lens in the first direction. The upward dimension, θ, is half the angle of the comfort zone of the human eye's visual field, and the first direction is a direction extending from the center of the first Fresnel lens away from the center.

Optionally, the first ratio ranges from 60% to 70%.

Optionally, the light blocking pattern is located on a side of the transparent substrate close to the first Fresnel lens.

Optionally, the transparent substrate has a through hole, and an orthographic projection of the through hole on the first plane overlaps an orthographic projection of the first region on the first plane.

Optionally, the transparent substrate is a first lens, and the light-blocking pattern is located on a side of the first lens close to the first Fresnel lens. The first lens includes a spherical lens, an aspherical lens, or a third lens. Two Fresnel lenses.

Optionally, the optical axis of the first lens is parallel to the optical axis of the first Fresnel lens, and a side of the first lens close to the first Fresnel lens is flat.

Optionally, the transparent substrate has a bearing surface, the light-blocking pattern is located on the bearing surface, and the bearing surface is parallel to the first plane.

Optionally, the light-blocking pattern includes a plurality of concentric annular patterns, and the width of the annular patterns is greater than 0 microns and less than or equal to 100 microns.

Optionally, the thickness of the transparent substrate ranges from 0.3 mm to 0.7 mm, and the thickness of the light blocking pattern ranges from 0.5 microns to 1.5 microns.

According to another aspect of the present application, a virtual reality device is provided, which includes: a display component and the above-mentioned Fresnel lens group.

Optionally, the display component is located on a side of the light blocking unit facing away from the first Fresnel lens, or the display component is located on a side of the first Fresnel lens facing away from the light blocking unit. .

The beneficial effects brought by the technical solutions provided by the embodiments of this application at least include:

A Fresnel lens group is provided, including: a first Fresnel lens and a light blocking unit. Wherein, the light-blocking unit includes a light-blocking pattern, the first Fresnel lens has a plurality of vertex angles, and the light-blocking pattern and at least part of the plurality of vertex angles are parallel to the optical axis of the first Fresnel lens. There is overlap in the direction, which can reduce the amount of light emitted from the ineffective surface of the first Fresnel lens, thereby reducing the stray light emitted from the first Fresnel lens, which can solve the problem of imaging of the Fresnel lens group in related technologies. The problem of poor quality has been achieved by improving the imaging quality of the Fresnel lens group.

Description of the drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without exerting creative efforts.

Figure 1 is a schematic structural diagram of a Fresnel lens;

Figure 2 is a schematic cross-sectional structural diagram of the Fresnel lens shown in Figure 1 along the position A1-A2;

Figure 3 is a schematic diagram of the optical path of the Fresnel lens shown in Figure 2 in the virtual reality device;

Figure 4 is a schematic structural diagram of a Fresnel lens group provided by an embodiment of the present application;

Figure 5 is a schematic cross-sectional structural diagram of the Fresnel lens group shown in Figure 4 along the position B1-B2;

Figure 6 is a schematic diagram of an image transmitted through a Fresnel lens group;

Figure 7 is a schematic structural diagram of a Fresnel lens provided by an embodiment of the present application;

Figure 8 is a schematic diagram of the visual field characteristics of the human eye;

Figure 9 is a schematic structural diagram of another Fresnel lens group provided by an embodiment of the present application;

Figure 10 is a schematic structural diagram of another Fresnel lens group provided by an embodiment of the present application;

Figure 11 is a schematic diagram of the light shielding experiment results of a Fresnel lens provided by the embodiment of the present application;

Figure 12 is a schematic diagram of the light shielding experiment results of another Fresnel lens provided by the embodiment of the present application;

Figure 13 is a schematic structural diagram of a virtual reality device provided by an embodiment of the present application;

FIG. 14 is a graph of a modulation transfer function of the optical path assembly shown in FIG. 13 .

Through the above-mentioned drawings, clear embodiments of the present application have been shown, which will be described in more detail below. These drawings and text descriptions are not intended to limit the scope of the present application's concepts in any way, but are intended to illustrate the application's concepts for those skilled in the art with reference to specific embodiments.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present application clearer, the embodiments of the present application will be further described in detail below with reference to the accompanying drawings.

Please refer to Figures 1 and 2. Figure 1 is a schematic structural diagram of a Fresnel lens. Figure 2 is a schematic cross-sectional structural diagram of the Fresnel lens shown in Figure 1 along the position A1-A2. The Fresnel lens 10 is a lens formed on the basis of an ordinary lens by using an etching process to remove excess optical material in the ordinary lens and only retaining the curvature of part of the surface. As shown in Figure 1, the surface of the Fresnel lens 10 can have multiple concentric rings ranging from small to large. Compared with ordinary lenses (such as spherical lenses or aspherical lenses), the Fresnel lens 10 weighs less. Light and thin.

As shown in FIG. 2 , one side of the Fresnel lens 10 has a sawtooth structure 11 , and the other side of the Fresnel lens 10 can be a spherical surface, an aspheric surface or a Fresnel surface. The sawtooth structure 11 includes a plurality of protrusions, each protrusion has an effective surface 111, an ineffective surface 112, and a vertex 113 connecting the effective surface 111 and the ineffective surface 112. The effective surface 111 is far away from the Fresnel lens relative to the ineffective surface 112. 10 in the center. In practical applications, the widths of the plurality of protrusions in the zigzag structure 11 can be equal to form equally spaced Fresnel lenses 10; or the heights of the plurality of protrusions in the zigzag structure 11 can be equal to form Fresnel lens with constant tooth height 10.

Figure 3 is a schematic diagram of the optical path of the Fresnel lens shown in Figure 2 in a virtual reality device. As shown in Figure 3, a virtual reality device includes a display component 13 and a lens located on one side of the light exit surface of the display component 13 The lens group may include the Fresnel lens 10. The light S11 emitted by the display component 13 enters the Fresnel lens 10 from the side of the Fresnel lens 10 with the sawtooth structure 11, and is refracted in the sawtooth structure 11. After exiting from the Fresnel lens 10, it enters the viewer's eyes 30. An enlarged virtual image 14 is formed at a certain distance in front of the viewer's eyes 30 .

It can be seen from Figure 3 that part of the light S12 in the light S11 emitted by the display component 13 is incident on the sawtooth structure 11 from the effective surface 111, and the light S12 is refracted only once inside the sawtooth structure 11. Exit Fresnel lens 10. Another part of the light S11 emitted by the display component 13 , S13 , is incident on the zigzag structure 11 from the vertex angle 113 , is refracted by a protrusion in the zigzag structure 11 , emerges from the ineffective surface 112 , and enters the adjacent After the second refraction occurs in the bulge, the Fresnel lens 10 emerges. Since the light incident from the vertex angle 113 and the effective surface 111 has different refraction times in the zigzag structure 101, its optical path is also different; and, through simulation testing According to the experimental results, it is found that the vertex angle 113 has the greatest influence on the amount of stray light formed by the Fresnel lens 10, making it easier for the light incident at the vertex angle 113 to form stray light after passing through the ineffective surface of the zigzag structure 101. As a result, the imaging quality of the Fresnel lens is poor, and the viewer has a poor experience when using the virtual display device.

It should be noted that in order to clearly illustrate the optical path of the Fresnel lens in Figure 3, other lenses in the lens group are not shown. The lens group may also include spherical lenses, in addition to the Fresnel lens shown in Figure 3. Various types of lenses such as Fresnel lenses other than the Neel lens 10 are not limited in the embodiments of the present application.

The Fresnel lens group and virtual reality device provided by the embodiments of the present application can solve the problems existing in the above related technologies.

Please refer to Figures 4 and 5. Figure 4 is a schematic structural diagram of a Fresnel lens group provided by an embodiment of the present application. Figure 5 is a schematic cross-sectional structural diagram of the Fresnel lens group shown in Figure 4 along the B1-B2 position. . The Fresnel lens group 20 may include: a first Fresnel lens 21 and a light blocking unit 22 .

One side of the first Fresnel lens 21 may have a zigzag structure, and the zigzag structure may include a plurality of protrusions 211 , and each protrusion 211 may have a vertex angle 2111 . The vertex angle 2111 can be used to connect the effective surface and the ineffective surface of the Fresnel lens 21 .

The light blocking unit 22 may be located outside the side of the first Fresnel lens 21 having a zigzag structure. The light blocking unit 22 may include a transparent base 221 and a light blocking pattern 222 located on the transparent base 221 . The light-blocking unit 22 may also include a light-transmitting area located in the transparent substrate 221. The light-transmitting area may refer to an area on the transparent substrate 221 where the light-blocking pattern 222 is not provided. The light-transmitting area may have better light transmittance.

The orthographic projection of the light blocking pattern 222 on the first plane S1 overlaps with the orthographic projection of at least part of the plurality of vertex angles 2111 on the first plane S1, and the first plane S1 is perpendicular to the first Fresnel The plane of the optical axis L1 of the Er lens 21. That is, the light blocking pattern 222 of the light blocking unit 22 and at least part of the vertex angles 2111 of the first Fresnel lens 21 are parallel to the optical axis L1 of the first Fresnel lens 21 Overlapping in the direction, the light-blocking pattern 222 can block at least part of the vertex corner 2111 to prevent light from irradiating at least part of the vertex corner 2111, or can prevent the light entering the first Fresnel lens 21 from passing through. At least part of the top corner exits. The first plane S1 is a virtual reference plane.

When light hits the Fresnel lens group 20, part of the light S01 can pass through the light blocking unit 22. The light-transmitting area of the first Fresnel lens 21 has a zigzag structure, and this part of the light S01 can be incident into the Fresnel lens 21 from the effective surface of the Fresnel lens 21, and pass through the Fresnel lens 21. A refraction occurs in the zigzag structure 101 of 21 to achieve the convergence effect of this part of the light S01. Another part of the light S02 can be blocked or absorbed by the light-blocking pattern 222 in the light-blocking unit 22 , which can prevent the part of the light S02 from being incident on the vertex angle 2111 of the first Fresnel lens 21 and being in the first Fresnel lens 21 After two refractions occur in the zigzag structure, stray light with a different optical path from the light S01 incident through the effective surface is formed. In this way, the amount of light emitted from the ineffective surface of the first Fresnel lens 21 can be reduced, thereby reducing the stray light emitted by the first Fresnel lens 21 , and preventing stray light from being emitted from the first Fresnel lens 21 into the user's eyes.

To sum up, embodiments of the present application provide a Fresnel lens group, including: a first Fresnel lens and a light blocking unit. Wherein, the light-blocking unit includes a light-blocking pattern, the first Fresnel lens has a plurality of vertex angles, and the light-blocking pattern and at least part of the plurality of vertex angles are parallel to the optical axis of the first Fresnel lens. There is overlap in the direction, which can reduce the amount of light emitted from the ineffective surface of the first Fresnel lens, thereby reducing the stray light emitted from the first Fresnel lens, which can solve the problem of imaging of the Fresnel lens group in related technologies. The problem of poor quality has been achieved by improving the imaging quality of the Fresnel lens group.

It should be noted that in the embodiment of the present application, the plurality of protrusions 211 in the zigzag structure of the first Fresnel lens 21 can be closed around the center of the first Fresnel lens 21 . Alternatively, the protrusion 211 may be in the shape of a closed ring, such as a circular ring, an ellipse, etc., or the protrusion 211 may be in a closed polygonal shape, such as a quadrilateral, a pentagon, etc.

Optionally, at least one side of the first Fresnel lens 21 may have a sawtooth structure, that is, one side of the first Fresnel lens 21 may have a sawtooth structure, and the other side may be a spherical surface or an aspheric surface, and the first Fresnel lens 21 may have a sawtooth structure. The Neel lens 21 is a single-sided Fresnel lens. Alternatively, both sides of the first Fresnel lens 21 may have a zigzag structure, and the first Fresnel lens 21 is a double-sided Fresnel lens, then the number of the light blocking units 22 may be two, and the two light blocking units 22 may be respectively located outside the two Fresnel surfaces of the first Fresnel lens 21 .

Optionally, as shown in FIGS. 4 and 5 , the first Fresnel lens 21 may have a first area 21 a and a second area 21 b located at the periphery of the first area 21 a. The second area 21b may surround the first area 21a, that is, the first area 21a may be surrounded by the second area 21b. The first area 21 a may be located at the middle position of the first Fresnel lens 21 , and the second area 21 b may be located at an edge position of the first Fresnel lens 21 . The shape of the first area 21a may be designed according to the shape of the first Fresnel lens 21. First area 21a It can be circular, square, hexagonal or other shapes, which are not limited in the embodiments of the present application.

The orthographic projection of the light blocking pattern 222 on the first plane S1 is located within the orthographic projection of the second area 21b on the first plane S1. That is, the orthographic projection of the light-blocking pattern 222 on the first plane S1 overlaps with the orthographic projection of the plurality of vertex corners 2111 in the second area 21b on the first plane S1, and the light-blocking pattern 222 is on the first plane. The orthographic projection on S1 does not overlap with the orthographic projection on the first plane S1 of the plurality of vertex corners 2111 in the first area 21a.

When the orthographic projection of the light-blocking pattern 222 on the first plane S1 overlaps with the orthographic projection of all the vertex angles 2111 in the first Fresnel lens 21 on the first plane S1, that is, the light-blocking pattern 222 has an impact on the first Fresnel lens 21. When all the vertex corners 2111 in the Fresnel lens 21 are blocked, the following two problems will occur: On the one hand, the area of the first Fresnel lens 21 blocked by the light blocking pattern 222 is larger, resulting in the first Fresnel lens 21 having a larger area. The light transmittance of lens 21 is low. On the other hand, when the user's eyes receive the light beam transmitted through the Fresnel lens group 20, the first area 21a (ie, the central area) is in the visual field comfort zone of the user's eyes. The light beam in the first area 21a (i.e., the center area) of the lens group 20 has a strong perception ability, resulting in a black circle in the image transmitted by the Fresnel lens group 20 actually seen by the user. This black circle can mean that the brightness is low. circular shadow. As shown in Figure 6, Figure 6 is a schematic diagram of an image transmitted through a Fresnel lens group. In the Fresnel lens group forming the image 201, the light-blocking pattern 22 overlaps with the plurality of vertices 2111 in the first area 21a, making the black circle 2011 in the central area of the image 201 more obvious, resulting in the imaging of the Fresnel lens group Poor quality.

Moreover, according to experiments, the problem of stray light in the edge area of the Fresnel lens group 20 is more serious than the problem of stray light in the center area of the Fresnel lens group 20 .

In this way, the plurality of vertex angles 2111 in the second area 21b of the first Fresnel lens 21 can be blocked by the light blocking pattern 222, so as to reduce stray light emitted by the first Fresnel lens 21, and at the same time, avoid By affecting the light transmittance of the first Fresnel lens 21, the imaging quality of the Fresnel lens group 20 can be improved as a whole.

Optionally, as shown in FIG. 7 , which is a schematic structural diagram of a Fresnel lens provided by an embodiment of the present application, the size of the second area 21 b in the first direction f1 is the same as that of the first Fresnel lens 21 The first ratio of the dimensions in the first direction f1 can satisfy the following formula:

T＝1-2×P×tanθ/D

Wherein, T is the first ratio, P is the distance between the light incident surface S2 of the first Fresnel lens 21 and the viewer's eyes 30 , and D is the size of the first Fresnel lens 21 in the first direction f1 , θ is half the angle of the human eye's visual field comfort zone, and the first direction f1 is from the center of the first Fresnel lens 21 to away from the center. The direction in which the heart direction extends. The comfort zone of the human eye's visual field can also be called the binocular comfort zone. It refers to objects within the comfort zone of the human eye's visual field. The human eye can see more clearly. The peripheral part located outside the comfort zone of the human eye's visual field can be called peripheral vision. It belongs to the relatively insensitive range of the human eye, that is, the area where the human eye cannot see clearly enough.

As shown in Figure 8, Figure 8 is a schematic diagram of the visual field characteristics of the human eye. Among them, E1 is the comfort zone of both eyes, and its angle range can be 0° to 60°; E2 is the overlapping visual zone of both eyes, and its angle range can be 90° to 120°; E3 is the full visual zone of both eyes, and its angle range can be 200° °～220°. The binocular overlapping visual field refers to the area where the left and right visual fields of the human eye overlap, and the binocular full visual field refers to the entire area of the left and right visual fields of the human eye.

For example, as shown in FIG. 7 , the visual field comfort zone of the human eye may be 60°, and θ may be 30°. P is 11 millimeters (mm), D is 40mm, the size C1 of the first area 21a in the first direction f1 is approximately 12.7mm (where C1=11×tan30°×2=12.7mm), and the second area 21b is The dimension C2 (not shown in the figure) in the first direction f1 may be 27.3mm (where C2=40-12.7=27.33mm). In this way, the ratio T of the size C2 of the second area 21b in the first direction f1 to the size D of the first Fresnel lens 21 in the first direction f1 may be 68.25% (where T=27.3/40=68.25) .

Or, taking half of the area of the first Fresnel lens 21 shown in FIG. 7 as an example for calculation, the size of the first area 21a in half of the first Fresnel lens 21 is about 6.35 mm (6.35 mm). mm≈11×tan30°), the size of the second area 21b in half of the first Fresnel lens 21 is approximately 13.65mm (13.65mm=20-6.35), then the second area 21b is in the first direction f1 The ratio of the size on to the size of the first Fresnel lens 21 in the first direction f1 is approximately 2/3 (2/3≈13.65/20=68.25%)

Optionally, the first ratio of the size of the second area 21b in the first direction f1 to the size of the first Fresnel lens 21 in the first direction f1 may range from 60% to 70%. Within this range, the light transmittance of the Fresnel lens group 20 is good, and the amount of stray light passing through the Fresnel lens group 20 is small.

For example, the first ratio of the size of the second area 21b in the first direction f1 to the size of the first Fresnel lens 21 in the first direction f1 is 2/3, then the area of the second area 21b is The second ratio to the area of the first Fresnel lens 21 can satisfy the formula: 1-(P×tan30°) ² /(D/2) ² , and the second ratio can be 8/9.

Optionally, as shown in FIG. 5 , the light blocking pattern 222 is located on a side of the transparent substrate 221 close to the first Fresnel lens 21 . The distance between the light-blocking pattern 222 and the vertex 2111 of the first Fresnel lens 21 can be made closer, so that the light-blocking range of the light-blocking pattern 222 can be more accurate. For example, the tooth height of the first Fresnel lens 21 is 0.5 mm, and the tooth spacing is 3 mm.

In the process of manufacturing the Fresnel lens assembly 20 , a light-blocking material layer may first be formed on the transparent substrate 221 , and then the light-blocking material layer may be patterned to obtain the light-blocking pattern 222 . The patterning process can include a photolithography process, and the photolithography error of the photolithography process can be less than 0.6 microns, which can make the size of the light-blocking pattern 222 formed by photolithography more accurate.

After the light-blocking pattern 222 is formed on the transparent substrate 221, the transparent substrate 221 with the light-blocking pattern 222 and the first Fresnel lens 21 are aligned and bonded. The alignment error can be less than 1.5 microns. Therefore, the orthographic projection of the light blocking pattern 222 on the first plane S1 overlaps with the orthographic projection of at least part of the vertex angles 2111 of the plurality of vertex angles 2111 on the first plane S1. In this way, light can be prevented from being incident on the zigzag structure of the first Fresnel lens 21 from the vertex angle 2111 of the first Fresnel lens 21 to form stray light, and the stray light emitted from the first Fresnel lens 21 can be reduced. astigmatism. At the same time, the light-blocking pattern 222 is formed on the transparent substrate 221. Compared with forming the light-blocking pattern 222 on the first Fresnel lens 21, damage to the sawtooth structure of the first Fresnel lens 21 can be avoided. The product yield of the first Fresnel lens 21 is improved.

Optionally, as shown in FIG. 9 , FIG. 9 is a schematic structural diagram of another Fresnel lens group provided by an embodiment of the present application. The transparent substrate 221 may have a through hole 2211, and an orthographic projection of the through hole 2211 on the first plane S1 overlaps with an orthographic projection of the first region 21a on the first plane S1. That is, the through hole 2211 can be formed in the area where the light blocking pattern 222 is not provided on the transparent substrate 221 . In this way, the light transmittance at the through hole 2211 of the transparent substrate 221 can be improved, and the material used for manufacturing the transparent substrate 221 can also be saved.

In an optional implementation, as shown in FIG. 10 , FIG. 10 is a schematic structural diagram of another Fresnel lens group provided by an embodiment of the present application. The transparent substrate 221 may be the first lens 23, and the light-blocking pattern 222 may be located on a side of the first lens 23 close to the first Fresnel lens 21. The first lens 23 may include a spherical lens, an aspherical lens, or a second Fresnel lens. . The first lens 23 can be reused as the transparent substrate 221 on the basis of having the lens function. The first lens 23 may be a lens adjacent to the first Fresnel lens 21 , and the light blocking pattern 222 may be provided on one side of the first lens 23 to block at least part of the first Fresnel lens 21 . Corner 2111 to block light. In this way, the structure of the Fresnel lens group 20 can be simplified, and further the structure of the virtual display device including the Fresnel lens group 20 can be simplified.

Optionally, as shown in FIG. 10 , the optical axis L2 of the first lens 23 is parallel to the optical axis L1 of the first Fresnel lens 21 , and the side of the first lens 23 close to the first Fresnel lens 21 is flat. In this way, the difficulty of forming the light-blocking pattern 222 on one side of the first lens 23 can be reduced, and the light-blocking range of the first Fresnel lens 21 by the light-blocking pattern 222 on the first lens 23 can be made more accurate.

Optionally, as shown in Figure 9, the transparent substrate 221 may have a bearing surface S3, and the light blocking pattern 222 is On the bearing surface S3, the bearing surface S3 is parallel to the first plane S1. The first Fresnel lens 21 may be a Fresnel lens with constant tooth height. Therefore, the distance between the light-blocking pattern 222 on the transparent substrate 221 and the plurality of vertices 2111 of the first Fresnel lens 21 is the same, thereby making the light transmission effect on the first Fresnel lens 21 more uniform.

In an optional implementation, the first Fresnel lens may be an equally spaced Fresnel lens. The transparent substrate may have multiple bearing surfaces, the light-blocking patterns are located on the multiple bearing surfaces, and the multiple bearing surfaces are all parallel to the first plane, and each of the multiple bearing surfaces is located on a different plane. So that the distance between the light-blocking pattern on the transparent substrate and the multiple vertices of the first Fresnel lens is the same.

Optionally, as shown in FIG. 4 , the light blocking pattern 222 may include a plurality of concentric annular graphics 2221 , and the width of the annular graphics 2221 is greater than 0 microns and less than or equal to 100 microns. The concentric annular graphics 2221 may be in a closed annular shape, such as a circular ring, an ellipse, etc., or the concentric annular graphics 2221 may be in a closed polygonal shape, such as a quadrilateral, a pentagon, etc.

For example, the width of the annular pattern 2221 can be 20 microns or 25.4 microns. In this way, the light-blocking pattern 222 can be prevented from blocking too much of the effective surface, and enough light can be ensured to enter the first Fresnel lens through the effective surface. , to ensure the light transmittance of the first Fresnel lens.

Optionally, the thickness of the transparent substrate 221 may range from 0.3 mm to 0.7 mm, and the thickness of the light blocking pattern 222 may range from 0.5 μm to 1.5 μm. The material of the light-blocking pattern 222 may be a black light-absorbing material. For example, the black light-absorbing material may be black resin, black matrix (such as black ink), etc., and the optical density value (OD) of the black light-absorbing material may be 0 to 5. /μm.

For example, the thickness of the transparent substrate may be 0.5 mm, the thickness range of the light-blocking pattern 222 may be 1.1 μm, and the optical density value of the black light-absorbing material may be 4/μm.

As shown in Figure 11, Figure 11 is a schematic diagram of the light shielding experiment results of a Fresnel lens provided by an embodiment of the present application. This experiment tests the transmittance of the same or the same type of Fresnel lens under four blocking conditions. The four occlusion situations include no occlusion, occlusion of the vertex corners in the Fresnel lens, occlusion of the ineffective surface in the zigzag structure of the Fresnel lens (the side walls of the zigzag structure as shown in Figure 11), and occlusion The ineffective surface and the vertex angle in the zigzag structure of the Fresnel lens (the side walls and the vertex corner of the zigzag structure as shown in Figure 11). According to the experimental results, it can be seen that blocking the vertex angle of the Fresnel lens can effectively reduce the stray light transmitted through the Fresnel lens, and at the same time, make the transmittance of the Fresnel lens better. Among them, the experimental results can be expressed by the shape and brightness of the spot R passing through the Fresnel lens.

As shown in Figure 12, Figure 12 is a schematic diagram of the light shielding experiment results of another Fresnel lens provided by the embodiment of the present application. This experiment covers two types of Fresnel lenses (241 and 242) respectively. The transmittance is tested under two conditions: blocked top corner and unblocked top corner. The apex angle of one type of Fresnel lens 242 may be larger than the apex angle of another type of Fresnel lens 241 . The experimental results are shown in Figure 12. For Fresnel lenses with different vertex angle sizes, at least part of the vertex angles can be blocked by light-blocking patterns, which can reduce the stray light emitted by the Fresnel lens.

Please refer to Figures 13 and 14. Figure 13 is a schematic structural diagram of a virtual reality device provided by an embodiment of the present application. Figure 14 is a graph of the modulation transfer function of the optical path component shown in Figure 13. The virtual reality device may include: a display component 41 and an optical path component 42. The optical path component 42 may include the Fresnel lens group 20 in any of the above embodiments. As shown in Figure 14, the abscissa is used to represent the number of line pairs per millimeter in space, and the ordinate is used to represent the modulation transfer function. The modulation transfer function curve (English: Modulation Transfer Function; abbreviation: MTF) refers to the relationship between the modulation degree and the number of line pairs per millimeter in the image. It is used to evaluate the ability of optical elements to restore scene details. Multiple curves are used to represent Test results of optical path components under different fields of view. The modulation transfer function curve in Figure 14 can correspond to the optical performance of the optical path component 42 in Figure 13. It can be seen from Figure 14 that the optical path component 42 in the embodiment of the present application can meet the optical performance requirements of conventional virtual display devices.

As shown in Figures 13 and 14, the optical path assembly 42 in the embodiment of the present application can include three Fresnel lens groups 20. The optical path assembly 42 can achieve a focal length of 20 mm, a total system length of 20 mm, and a field of view (FOV) of 90 °, Eye box 8×8mm effect. Among them, two Fresnel lenses in the three Fresnel lens groups 20 may have one Fresnel surface S4, and the other Fresnel lens may have two Fresnel surfaces S4. The Fresnel lens assembly provided by the embodiment of the present application can effectively reduce the thickness of the lens assembly (thickness is less than or equal to 30 mm), and at the same time can achieve high light efficiency (light efficiency is greater than or equal to 80%).

Since the straight-through aspherical lens group has the characteristics of low design and processing, high light efficiency (>80%), and no stray light, the total length of the system is thick (>35mm), which is not conducive to the thinning of the product; foldback The Pancake (English: Pancake) lens group has the characteristics of better imaging quality and thin total system length (≤30mm), but the folding lens group has lower light efficiency (<25%). Compared with the above-mentioned straight-through aspherical surface Lens group and folding lens group, the optical path assembly in the embodiment of the present application can be called a through-type Fresnel lens group. The through-type Fresnel lens group can have the characteristics of high light efficiency and a lightweight and thin lens group.

Optionally, as shown in FIG. 13 , the display component 41 may be located on the side of the light blocking unit 22 facing away from the first Fresnel lens 21 , or the display component 41 may be located on the side of the first Fresnel lens 21 facing away from the light blocking unit 22 . one side. The display component 41 can emit an image beam, and the light incident surface of the Fresnel lens group 20 can receive the image beam and guide the image beam into the interior of the Fresnel lens group 20 .

For example, as shown in FIG. 13 , the light incident surface of the Fresnel lens group 20 can be located on the side of the light blocking unit 22 away from the first Fresnel lens 21 , that is, the image beam can pass through the Fresnel lens group 20 . One side of the light blocking unit 22 is incident on the Fresnel lens group 20 . Alternatively, the light incident surface of the Fresnel lens group 20 can be located on the side of the first Fresnel lens 21 away from the light blocking unit 22 , that is, the image beam can pass through the first Fresnel lens 21 in the Fresnel lens group 20 . One side enters the Fresnel lens group 20.

Optionally, the first Fresnel lens 21 and the light blocking unit 22 may be bonded through a box-joining process. Alternatively, the virtual reality device may also include a fixed bracket, and the first Fresnel lens and the light-blocking unit in the Fresnel lens group are respectively fixedly connected to the fixed bracket.

To sum up, embodiments of the present application provide a virtual display device. The virtual display device includes a display component and a Fresnel lens group, where the Fresnel lens group includes: a first Fresnel lens and a light blocking unit. . The light-blocking unit includes a light-blocking pattern. The first Fresnel lens has a plurality of vertex angles. The light-blocking pattern is aligned with at least part of the plurality of vertex angles in a direction parallel to the optical axis of the first Fresnel lens. There is overlap on the lens, which can reduce the amount of light emitted from the ineffective surface of the first Fresnel lens, thereby reducing the stray light emitted from the first Fresnel lens, which can solve the problem of poor imaging quality of the Fresnel lens group in related technologies. This solves the problem of poor quality and achieves the effect of improving the imaging quality of the Fresnel lens group.

It should be noted that in the accompanying drawings, the dimensions of layers and regions may be exaggerated for clarity of illustration. Also, it will be understood that when an element or layer is referred to as being "on" another element or layer, it can be directly on the other element or intervening layers may be present. In addition, it will be understood that when an element or layer is referred to as being "under" another element or layer, it can be directly under the other element or more intervening layers or elements may be present. In addition, it will also be understood that when a layer or element is referred to as being "between" two layers or elements, it can be the only layer between the two layers or elements, or more intervening layers may also be present. or component. Similar reference numbers indicate similar elements throughout.

In this application, the terms "first", "second", "third" and "fourth" are used for descriptive purposes only. and should not be construed as indicating or implying relative importance. The term "plurality" refers to two or more than two, unless expressly limited otherwise.

The above are only optional embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the protection of the present application. within the range.

Claims

A Fresnel lens group, characterized in that the Fresnel lens group includes: a first Fresnel lens and a light blocking unit;

One side of the first Fresnel lens has a sawtooth structure, the sawtooth structure includes a plurality of protrusions, and the protrusions have a vertex angle;

The light-blocking unit is located outside the side of the first Fresnel lens with the zigzag structure. The light-blocking unit includes a transparent base and a light-blocking pattern located on the transparent base. The light-blocking pattern The orthographic projection on the first plane overlaps with the orthographic projection of at least part of the plurality of vertex angles on the first plane, and the first plane is perpendicular to the first Fresnel The plane of the optical axis of the lens.
The Fresnel lens group according to claim 1, wherein the first Fresnel lens has a first area and a second area located at the periphery of the first area;

The orthographic projection of the light blocking pattern on the first plane is located within the orthographic projection of the second area on the first plane.
The Fresnel lens assembly according to claim 2, wherein the size of the second area in the first direction is equal to the size of the first Fresnel lens in the first direction. A ratio that satisfies the following formula:
T＝1-2×P×tanθ/D

Wherein, T is the first ratio, P is the distance between the light incident surface of the first Fresnel lens and the viewer’s eyes, and D is the position of the first Fresnel lens in the first direction. The upward dimension, θ, is half the angle of the comfort zone of the human eye's visual field, and the first direction is a direction extending from the center of the first Fresnel lens away from the center.
The Fresnel lens group according to claim 3, wherein the first ratio ranges from 60% to 70%.
The Fresnel lens assembly according to claim 1, wherein the light blocking pattern is located on a side of the transparent substrate close to the first Fresnel lens.
The Fresnel lens group according to claim 2, wherein the transparent substrate has a through hole, and the orthographic projection of the through hole on the first plane is consistent with the first area on the first plane. Orthographic projection on a plane with overlap.
The Fresnel lens assembly according to claim 1, wherein the transparent substrate is a first lens, and the light-blocking pattern is located on a side of the first lens close to the first Fresnel lens, so The first lens includes a spherical lens, an aspherical lens or a second Fresnel lens.
The Fresnel lens assembly according to claim 7, wherein the optical axis of the first lens is parallel to the optical axis of the first Fresnel lens, and the first lens is close to the first lens. One side of the Fresnel lens is flat.
The Fresnel lens assembly according to claim 1, wherein the transparent base has a bearing surface, the light-blocking pattern is located on the bearing surface, and the bearing surface is parallel to the first plane.
The Fresnel lens set according to claim 1, wherein the light-blocking pattern includes a plurality of concentric annular graphics, and the width of the annular graphics is greater than 0 microns and less than or equal to 100 microns.
The Fresnel lens assembly according to claim 1, wherein the thickness of the transparent substrate ranges from 0.3 mm to 0.7 mm, and the thickness of the light blocking pattern ranges from 0.5 microns to 1.5 microns.
A virtual reality device, characterized by comprising: a display component and the Fresnel lens group according to any one of claims 1 to 11.
The virtual reality device according to claim 12, wherein the display component is located on a side of the light blocking unit away from the first Fresnel lens, or the display component is located on the first Fresnel lens. The side of the lens facing away from the light blocking unit.