Light guide device, optical module and display equipment

Abstract

The embodiment of the invention provides a light guide device, an optical module and display equipment. The light guide device comprises a substrate, and a first grating region, a second grating region and a third grating region which are arranged on the substrate, the first grating area is used for coupling light into the substrate and generating first diffraction light propagating towards the direction of the second grating area; the second grating area receives the first diffraction light and can generate second diffraction light propagating towards the third grating area, and the third grating area receives the second diffraction light and can generate third diffraction light diffracted towards the second grating area. The second diffracted light and the third diffracted light are subjected to pupil expansion in the second grating area along two different dimensions and are coupled out.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of optical technology, and more specifically, the embodiments of the present application relate to a light guide device, an optical module and a display device. Background Art

[0002] Display devices such as head-mounted display devices are now widely used in the field of science and technology, such as augmented reality (AR) display devices, etc. In the above display devices, light guide devices play a vital role, which are used to guide light from a light source to the user's eyes.

[0003] At present, the mainstream pupil expansion solution in the diffraction waveguide solution is mainly the two-dimensional grating pupil expansion solution. Although the two-dimensional grating solution has a compact layout, the optical structure design is relatively complex, resulting in high costs. Therefore, developing a light guide device with both a compact layout and a simple design has become a research focus in this field. Summary of the invention

[0004] The purpose of this application is to provide a new technical solution for a light-guiding device, an optical module and a display device.

[0005] In a first aspect, an embodiment of the present application provides a light guide device. The light guide device includes a substrate and a first grating region, a second grating region, and a third grating region disposed on the substrate;

[0006] The first grating region is used to couple light into the substrate and generate first diffracted light propagating toward the second grating region;

[0007] The second grating area receives the first diffraction light and can generate a second diffraction light propagating toward the third grating area. The third grating area receives the second diffraction light and can generate a third diffraction light diffracted toward the second grating area. The second diffraction light and the third diffraction light are expanded and coupled out along two different dimensions in the second grating area.

[0008] Optionally, a set angle θ2 is formed between the direction of the grating vector K1 of the first grating area and the direction of the grating vector K3 of the third grating area, and 30°≤θ2≤150°.

[0009] Optionally, the first grating region, the second grating region and the third grating region form a closed grating vector polygon, so that the exit angle of the light is consistent with the incident angle when the light is coupled out through the second grating region.

[0010] Optionally, a one-dimensional grating is arranged in the second grating region.

[0011] Optionally, a one-dimensional grating or a two-dimensional grating is arranged in the first grating area.

[0012] Optionally, a one-dimensional grating is arranged in the third grating region.

[0013] Optionally, the light guiding device is a diffractive light waveguide lens;

[0014] The first grating region, the second grating region and the third grating region are located on a surface of the substrate along its thickness direction; or,

[0015] The first grating region, the second grating region and the third grating region are arranged on two opposite surfaces of the substrate along the thickness direction of the substrate.

[0016] Optionally, the grating types of the first grating region, the second grating region and the third grating region include volume holographic grating, surface relief grating or photonic crystal.

[0017] In a second aspect, an embodiment of the present application provides an optical module. The optical module includes the light guide device as described in the first aspect; and

[0018] An optical machine is used to project light onto the light-guiding device, and the light projected by the optical machine can cover the first grating area.

[0019] In a third aspect, an embodiment of the present application provides a display device. The display device includes:

[0020] casing; and

[0021] As in the optical module of the second aspect, the optical module is disposed in the housing.

[0022] The beneficial effects of this application are:

[0023] According to an embodiment of the present application, a light guide device is provided, which can be used in an augmented reality display device. The design realizes effective coupling-in, directional propagation and pupil expansion coupling-out of light through the coordinated work of three grating areas. Compared with traditional light guide devices, the light guide device provided in the embodiment of the present application has the characteristics of compact grating structure design, and can make full use of the energy of light, thereby improving the propagation efficiency and utilization rate of incident light.

[0024] Other features and advantages of the present specification will become apparent from the following detailed description of exemplary embodiments of the present specification with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the specification and, together with the description, serve to explain the principles of the specification.

[0026] Figure 1A schematic diagram of the structure of a light guide device provided in an embodiment of the present application;

[0027] Figure 2 A grating vector closed diagram of the light guide device provided in an embodiment of the present application;

[0028] Figure 3 A light path diagram of the light guiding device provided in an embodiment of the present application.

[0029] Description of reference numerals:

[0030] 1. First grating area; 2. Second grating area; 3. Third grating area; 4. Substrate; 01. First diffraction light; 02. Second diffraction light; 03. Third diffraction light; 04. Outcoupled light. DETAILED DESCRIPTION

[0031] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that unless otherwise specifically stated, the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application.

[0032] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present application, its application, or uses.

[0033] Techniques and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the techniques and equipment should be considered part of the specification.

[0034] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0035] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0036] The light guide device, optical module and display device provided in the embodiments of the present application are described in detail below in conjunction with the accompanying drawings.

[0037] According to one embodiment of the present application, a light guide device is provided. Figure 1 and Figure 3The light guide device includes a substrate 4 and a first grating area 1, a second grating area 2 and a third grating area 3 arranged on the substrate 4. The first grating area 1 is used to couple light into the substrate 4 and generate a first diffraction light 01 propagating in the direction of the second grating area 2; the second grating area 2 receives the first diffraction light 01 and can generate a second diffraction light 02 propagating in the direction of the third grating area 3, the third grating area 3 receives the second diffraction light 02 and can generate a third diffraction light 03 diffracted toward the second grating area 2, and the second diffraction light 02 and the third diffraction light 03 are pupil-expanded and coupled out in the second grating area 2 along two different dimensions.

[0038] According to the light guide device provided in the embodiment of the present application, see Figure 3 The second diffraction light 02 and the third diffraction light 03 can be spread along two different dimensions in the second grating area 2, thereby achieving a two-dimensional pupil expansion effect. The outcoupled light 04 coupled out through the second grating area 2 can cover the entire second grating area 2.

[0039] According to the light guide device provided in the embodiment of the present application, see Figure 1 , comprising a substrate 4, the substrate 4 being, for example, a transparent substrate, on which at least three grating regions with different functions are arranged, namely, a first grating region 1, a second grating region 2, and a third grating region 3. The three grating regions each have a different function and work together to achieve light coupling-in, directional propagation, and pupil expansion coupling-out.

[0040] The main function of the first grating area 1 is to receive incident light projected from the outside, and couple the incident light into the inside of the substrate 4 through the diffraction effect of the grating. Once the incident light is coupled into the inside of the substrate 4, it will be converted into the first diffraction light 01 and propagate in the direction of the second grating area 2. This ensures that the incident light projected from the outside can effectively enter the inside of the substrate 4 of the light guide device and continue to propagate.

[0041] The second grating area 2 is used to receive the first diffracted light 01 from the first grating area 1. After being diffracted again by the second grating area 2, the first diffracted light 01 is transformed into the second diffracted light 02, and still maintains the original propagation direction, that is, continues to propagate toward the third grating area 3. In this light propagation process, the light achieves directional transmission inside the substrate 4.

[0042] After receiving the second diffraction light 02, the third grating area 3 generates a third diffraction light 03 through its specific grating structure. This light does not continue to propagate forward, but turns to propagate in the direction of the second grating area 2. In this way, the pupil expansion of the light in two different dimensional directions is achieved in the same area. It is worth noting that the light after pupil expansion can be effectively utilized and transmitted in the entire second grating area 2, further improving the optical performance and light efficiency of the light guide device.

[0043] The light guide device provided in the embodiment of the present application is designed to achieve effective light coupling, directional propagation and pupil expansion coupling through the coordinated work of three grating areas. Compared with traditional light guide devices, this has the characteristics of compact grating structure design, and can fully utilize the energy of light, thereby improving the propagation efficiency and utilization rate of incident light.

[0044] In some examples of the present application, a set angle θ2 is formed between the direction of the grating vector K1 of the first grating region 1 and the direction of the grating vector K3 of the third grating region 3, and 30°≤θ2≤150°.

[0045] The first grating area 1 is used to couple the incident light into the interior of the substrate 4, and make the light propagate through total reflection inside the substrate 4, that is, the first grating area 1 is the coupling-in area of ​​the light-guiding device. The second grating area 2 forms a pupil expansion and out-coupling area. The third grating area 3 is an auxiliary pupil expansion area, which is mainly used to assist the second grating area 2 in achieving the pupil expansion effect of the light. Finally, the light after pupil expansion is re-diffracted and returns to the second grating area 2 to form out-coupling light 04.

[0046] According to this example, the relationship between the grating vector directions of the first grating region 1 and the third grating region 3 of the light guiding device is described.

[0047] The set angle θ2 is the angle between the direction of the grating vector K1 of the first grating area 1 and the direction of the grating vector K3 of the third grating area 3, and the range of the set angle θ2 is 30° to 150°. This means that the directions between K1 and K3 are not completely parallel or perpendicular, but have a certain inclination angle. Such a design brings the following advantages:

[0048] (1) By optimizing the range of the set angle θ2, the propagation path of the light and the degree of pupil expansion can be further controlled. This provides designers with greater flexibility and allows them to adjust and optimize the optical performance of the light guide device according to specific application requirements.

[0049] (2) In optical imaging devices such as head-mounted display devices, the performance of the light guide device directly affects the brightness and uniformity of the image. By reasonably setting the set angle θ2, the distribution and transmission of light can be optimized, thereby improving the display quality of the image and providing users with a better visual experience.

[0050] In general, the light guide device design that effectively diffuses light and improves display quality is achieved by setting the angle range of the grating vector direction between the first grating area 1 and the third grating area 3. This design improves the performance of the light guide device.

[0051] In addition, an angle θ3 is formed between the grating vector K1 of the first grating area 1 and the grating vector K2 of the second grating area 2. The angle θ3 can be designed to be 50° to 70°, for example, and the present application does not impose any limitation on this.

[0052] According to the light guide device provided in the embodiment of the present application, the grating period of the first grating area 1 is D1, the grating period of the second grating area 2 is D2, and the grating period of the third grating area 3 is D3. The relationship between the periods of the three grating areas is shown in FIG. Figure 2 According to the sine theorem, we can obtain: sinθ1 / D1=sinθ2 / D2=sinθ3 / D3; wherein the angle θ1 is the angle between the grating vector K2 of the second grating area 2 and the grating vector K3 of the third grating area 3.

[0053] The above describes the relationship between the grating periods of the first grating area 1, the second grating area 2 and the third grating area 3 of the light guide device. These grating periods will affect the propagation of light and the pupil expansion effect.

[0054] The grating period D1 of the first grating region 1 can be set, for example, to be between 200 nm and 600 nm. Selecting D1 within this range can ensure that the first grating region 1 couples the externally projected light into the substrate 4 and generates the first diffracted light O1 propagating toward the second grating region 2 .

[0055] The grating period D2 of the second grating region 2 satisfies: sinθ1 / D1=sinθ2 / D2=sinθ3 / D3. Figure 2 The angle θ2 is the angle between the grating vector K3 of the third grating area 3 and the grating vector K1 of the first grating area 1. By adjusting the angle θ2, the diffraction effect of the second grating area 2 on the first diffracted light 01 can be accurately controlled, thereby ensuring that the light can propagate in a predetermined direction and generate the second diffracted light 02.

[0056] For the grating period D3 of the third grating region 3, it satisfies: sinθ1 / D1=sinθ2 / D2=sinθ3 / D3. Figure 2 , the angle θ3 is the angle between the grating vector K2 of the second grating area 2 and the grating vector K1 of the first grating area 1. This relationship ensures that the third grating area 3 can smoothly receive the second diffraction light 02 and generate the third diffraction light 03 diffracted toward the second grating area 2. By precisely controlling D3, the diffraction behavior of the third diffraction light 03 can be optimized, and ultimately the two-dimensional pupil expansion of the light can be achieved in the second grating area 2.

[0057] In some examples of the present application, the first grating region 1, the second grating region 2 and the third grating region 3 form a closed grating vector polygon so that the exit angle of the light is consistent with the incident angle when the light is coupled out through the second grating region 2.

[0058] See also Figure 2 , the grating vectors between the first grating area 1, the second grating area 2 and the third grating area 3 of the light-guiding device form a closed polygonal structure, which means that the grating vector directions of the three grating areas (i.e., K1, K2 and K3) are interrelated, and they form a closed figure in a set manner. This closed structure helps the light to propagate and diffract in a specific way between the grating areas, which can reduce the loss and scattering of light, thereby improving the utilization rate of light. Secondly, this design ensures that when the light is coupled out through the second grating area 2, its exit angle is consistent with the incident angle, which is very important, because maintaining the consistency of the incident and exit angles can ensure that the propagation direction of the light will not change unexpectedly when passing through the light-guiding device, thereby ensuring that the coupled light will not be distorted, and the formed image will not be deformed, which can improve the user's visual experience.

[0059] In some examples of the present application, a one-dimensional grating is arranged in the second grating region 2 .

[0060] For example, only a single one-dimensional grating may be arranged in the second grating area 2, which can simplify the grating design of the second grating area 2. When a one-dimensional grating is adopted in the second grating area 2, it cooperates with the third grating area 3 arranged on one side thereof, so that the one-dimensional grating area can achieve the effect of two-dimensional pupil expansion and outcoupling with the help of the third grating area 3.

[0061] That is to say, the light-guiding device provided in the embodiment of the present application can use a one-dimensional grating to achieve a two-dimensional pupil expansion effect. The overall grating layout is more compact and the grating design is relatively simple, which can reduce the processing difficulty and production cost of the light-guiding device.

[0062] In some examples of the present application, the first grating region 1 includes a one-dimensional grating or a two-dimensional grating.

[0063] That is to say, the first grating region 1 can be composed of a single one-dimensional grating or a two-dimensional grating, a plurality of one-dimensional gratings or a plurality of two-dimensional gratings. The first grating region 1 is the coupling region of the light guide device, and the grating type of the first grating region 1 can be designed according to the coupling efficiency requirements.

[0064] In some examples of the present application, a one-dimensional grating is arranged in the third grating region 3 .

[0065] One-dimensional gratings can be provided for both the third grating area 3 and the second grating area 2. When one-dimensional gratings are used for both, two one-dimensional gratings can be matched to realize two-dimensional pupil expansion of light in the area of ​​one-dimensional grating. The combination of two one-dimensional gratings can improve optical efficiency, simplify the grating structure design on the light guide device, and reduce production costs.

[0066] In some examples of the present application, the light guide device is a diffractive light waveguide lens. The first grating area 1, the second grating area 2 and the third grating area 3 are located on a surface of the substrate 4 along its thickness direction, see Figure 1 and Figure 3 ; or, the first grating region 1, the second grating region 2 and the third grating region 3 are arranged on two opposite surfaces of the substrate 4 along its own thickness direction.

[0067] According to this example, two different layouts of the first grating area 1, the second grating area 2 and the third grating area 3 on the substrate 4 are described when the light guide device is used as a diffractive light waveguide lens.

[0068] For the first layout, the first grating area 1, the second grating area 2 and the third grating area 3 are all located on one surface of the substrate along its thickness direction. This layout means that all grating areas are concentrated on one surface, which is conducive to simplifying the manufacturing process because the grating only needs to be etched or processed on one surface. In addition, this layout may also make the propagation path of light more compact, which helps to reduce the size of the entire light guide device.

[0069] For the second layout, the first grating area 1, the second grating area 2 and the third grating area 3 are arranged on two opposite surfaces of the substrate 4 along its thickness direction. This layout helps to reduce the mutual influence between the grating areas because they are distributed on both sides of the substrate. This design may make the propagation of light more stable and reduce the light loss or deformation caused by the interference between the grating areas.

[0070] The above two layout methods have their own advantages and disadvantages. The first layout method simplifies the manufacturing process and may reduce the size of the device. The second layout method improves the stability of light propagation. As for which layout method to choose, it depends on the specific application requirements and manufacturing conditions. When pursuing simplified manufacturing and reduced size, the first layout method can be selected. When there are higher requirements for light propagation stability, the second layout method can be selected.

[0071] Optionally, the grating types of the first grating region 1, the second grating region 2 and the third grating region 3 include volume holographic grating, surface relief grating or photonic crystal.

[0072] By using volume holographic gratings, surface relief gratings or photonic crystals as the grating type in the light guide device, precise control of light and efficient pupil expansion can be achieved. Each of these grating types has unique advantages and application ranges. The appropriate grating type can be selected according to specific application requirements to optimize the performance of the light guide device.

[0073] According to the light-guiding device provided in the embodiment of the present application, it can be, for example, a diffractive light waveguide lens, which can be suitable for application in a display device, such as a head mounted display (HMD). Furthermore, the display device can be an AR head mounted display device.

[0074] Of course, the light guiding device may also be a diffractive optical element in other forms.

[0075] According to another embodiment of the present application, an optical module is provided, which includes the above-mentioned light guide device and an optical engine, wherein the optical engine is used to project light to the light guide device, and the light projected by the optical engine can cover the first grating area 1 .

[0076] The imaging light emitted by the optical machine may be monochromatic light or polychromatic light.

[0077] The light is directly projected onto the first grating area 1 of the light guide device by an optical machine, thereby ensuring efficient use of the light. Since the first grating area 1 is the entrance for the light to enter the light guide device, it is crucial to ensure that the light covers this area.

[0078] Since the three grating areas of the light guide are well designed, the light projected by the optical machine will be precisely controlled and the pupil will be expanded when passing through these grating areas. This helps to optimize the performance of the entire optical module and improve the brightness and clarity of the image.

[0079] The optical module provided in the embodiments of the present application can be used in, for example, a display device, and specifically can be used in AR glasses or an AR helmet.

[0080] According to another embodiment of the present application, a display device is provided, comprising: a housing and the optical module as described above, wherein the optical module is disposed in the housing.

[0081] The specific implementation of the optical module and the display device of the embodiments of the present application can refer to the above-mentioned embodiments of the light guide device, so it at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be repeated here one by one.

[0082] The above embodiments focus on the differences between the various embodiments. As long as the different optimization features between the various embodiments are not contradictory, they can be combined to form a better embodiment. Considering the simplicity of the text, they will not be repeated here.

[0083] Although some specific embodiments of the present application have been described in detail by way of example, it should be understood by those skilled in the art that the above examples are only for illustration, not for limiting the scope of the present application. It should be understood by those skilled in the art that the above embodiments may be modified without departing from the scope and spirit of the present application. The scope of the present application is defined by the appended claims.

Claims

1. A light guide device, characterized in that: It comprises a substrate (4) and a first grating region (1), a second grating region (2) and a third grating region (3) arranged on the substrate (4); The first grating region (1) is used to couple light into the substrate (4) and generate a first diffraction light (01) propagating in the direction of the second grating region (2); The second grating area (2) receives the first diffraction light (01) and is capable of generating a second diffraction light (02) that propagates toward the third grating area (3); the third grating area (3) receives the second diffraction light (02) and is capable of generating a third diffraction light (03) that diffracts toward the second grating area (2); the second diffraction light (02) and the third diffraction light (03) are pupil-expanded and coupled out along two different dimensions in the second grating area (2).

2. The light guide device according to claim 1, characterized in that: A set angle θ2 is formed between the direction of the grating vector K1 of the first grating area (1) and the direction of the grating vector K3 of the third grating area (3), and 30°≤θ2≤150°.

3. The light guide device according to claim 1, characterized in that: The first grating region (1), the second grating region (2) and the third grating region (3) form a closed grating vector polygon, so that when light is coupled out through the second grating region (2), the exit angle of the light is consistent with the incident angle.

4. The light guide device according to claim 1, characterized in that: A one-dimensional grating is arranged in the second grating area (2).

5. The light guide device according to claim 4, characterized in that: A one-dimensional grating or a two-dimensional grating is arranged in the first grating area (1).

6. The light guide device according to claim 4, characterized in that: A one-dimensional grating is arranged in the third grating area (3).

7. The light guide device according to any one of claims 1 to 6, characterized in that: The light guide device is a diffractive light waveguide lens; The first grating region (1), the second grating region (2) and the third grating region (3) are located on a surface of the substrate (4) along its thickness direction; or, The first grating region (1), the second grating region (2) and the third grating region (3) are respectively arranged on two surfaces of the substrate (4) which are opposite to each other along the thickness direction thereof.

8. The light guide device according to claim 7, characterized in that: The grating types of the first grating area (1), the second grating area (2) and the third grating area (3) include volume holographic grating, surface relief grating or photonic crystal.

9. An optical module, characterized in that: include: The light guide device according to any one of claims 1 to 8; as well as An optical machine, the optical machine is used to project light onto the light-guiding device, and the light projected by the optical machine can cover the first grating area (1).

10. A display device, characterized in that: include: shell; and The optical module according to claim 9, wherein the optical module is disposed in the housing.

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