Coating method for light guide device, light guide device and head-mounted display apparatus

Abstract

Provided in the embodiments of the present application are a coating method for a light guide device, a light guide device and a head-mounted display apparatus. The coating method for a light guide device comprises: providing a substrate, a coupling-in area and a coupling-out area being formed on the substrate; when the coupling-out area is shielded, forming a metal layer in the coupling-in area, and controlling the thickness of the metal layer to be greater than 15 nm; and, when the coupling-in area is not shielded, forming a non-metal material layer on the substrate, the non-metal material layer at least covering the coupling-out area.

Description

Coating method for light guide device, light guide device and head-mounted display device

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on November 13, 2023, with application number 202311511153.8 and invention name “Coating method for light guide device, light guide device and head-mounted display device”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The embodiments of the present application relate to the field of optical imaging technology. More specifically, the embodiments of the present application relate to a coating method for a light guide device, a light guide device, and a head-mounted display device. Background Art

[0003] Augmented reality (AR) technology integrates virtual information with the real world. Diffractive waveguides are currently considered the best optical display solution for AR. Diffractive waveguides often require separate coating regions. For example, the incoupling and outcoupling regions may have different coating materials and thicknesses. Therefore, the process requires masking one region before depositing the film, and then masking the other region before depositing the film.

[0004] Summary of the Invention

[0005] The purpose of this application is to provide a coating method for a light-guiding device, a light-guiding device, and a new technical solution for a head-mounted display device.

[0006] In a first aspect, the present application provides a coating method for a light guide device. The coating method for a light guide device comprises:

[0007] Providing a substrate, and forming an incoupling region and an outcoupling region on the substrate;

[0008] forming a metal layer on the incoupling region while shielding the outcoupling region, and controlling the thickness of the metal layer to be greater than 15 nm; and

[0009] A non-metallic material layer is formed on the substrate without shielding the coupling-in region, and the non-metallic material layer at least covers the coupling-out region.

[0010] Optionally, the coupling-in region includes a coupling-in grating, and the structure of the metal layer corresponds to the structure of the coupling-in grating.

[0011] Optionally, the thickness of the metal layer is H, and 16 nm ≤ H ≤ 100 nm.

[0012] Optionally, the material of the metal layer includes aluminum, gold, copper or silver.

[0013] Optionally, the metal layer is further covered with the non-metallic material layer;

[0014] The outcoupling region includes an outcoupling grating and the non-metallic material layer covering the outcoupling grating, and the incoupling grating and the outcoupling grating form a closed grating vector polygon.

[0015] Optionally, the metal layer is formed in the coupling-in region by a deposition method, wherein the deposition method includes atomic layer deposition ALD, physical vapor deposition PVD, high temperature gas phase reaction CVD or plasma enhanced chemical vapor deposition PECVD.

[0016] Optionally, the non-metallic material layer is made of silicon oxide, titanium oxide, aluminum oxide or embossing glue.

[0017] In a second aspect, an embodiment of the present application provides a light guide device, which is manufactured using the coating method for a light guide device as described in the first aspect.

[0018] In a third aspect, an embodiment of the present application provides a light guide device, the light guide device comprising a substrate, and an incoupling region and an outcoupling region disposed on the substrate;

[0019] The coupling region is at least covered with a metal layer;

[0020] The outcoupling region is covered with a non-metallic material layer.

[0021] In a fourth aspect, an embodiment of the present application provides a head-mounted display device, comprising:

[0022] a housing; and

[0023] The light guiding device as described in the second aspect or the third aspect.

[0024] The beneficial effects of this application are:

[0025] According to the coating method of the light-guiding device provided in the embodiment of the present application, a metal layer of a certain thickness is first formed in the coupling-in area, and when a non-metallic material layer is formed in the coupling-out area, the coupling-in area does not need to be shielded. This is because the metal material has a skin effect. After exceeding its skin depth, the excess thickness of the metal layer will no longer affect the diffraction behavior of the coupling-in area. The design of the metal layer makes it unnecessary to shield the coupling-in area when the non-metallic material layer is formed on the coupling-out area, thereby effectively reducing the number of steps and lowering the production cost.

[0026] 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

[0027] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the specification and, together with the description, serve to explain the principles of the specification.

[0028] FIG1 is a schematic structural diagram of a light guide device provided in an embodiment of the present application;

[0029] FIG2 is a schematic diagram of forming a metal layer on the coupling-in region according to an embodiment of the present application;

[0030] FIG3 is a diffraction efficiency curve of the metal layer shown in FIG2 ;

[0031] FIG4 is a schematic diagram of forming a non-metallic material layer on the metal layer in FIG2 ;

[0032] FIG5 is a diffraction efficiency curve of a non-metallic material layer covered on the metal layer shown in FIG4 ;

[0033] FIG6 is a schematic diagram of covering the coupling-in region of the light guide device with a silicon oxide layer;

[0034] FIG7 is a diffraction efficiency curve of the coupling-in region shown in FIG6 ;

[0035] FIG8 is a schematic diagram of stacking a titanium oxide layer and a silicon oxide layer in the coupling-in region of a light guide device;

[0036] FIG. 9 is a diffraction efficiency curve of the coupling-in region shown in FIG. 8 .

[0037] Description of reference numerals: 100, substrate; 101, coupling-in region; 102, coupling-out region; 200, metal layer; 300, non-metal material layer; 400, titanium oxide layer; 500, silicon oxide layer. DETAILED DESCRIPTION

[0038] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that unless otherwise specifically stated, the relative arrangements of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application.

[0039] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present disclosure, its application, or uses.

[0040] 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.

[0041] 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.

[0042] It should be noted that like reference numerals and letters refer to like items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0043] The coating method of the light guide device, the light guide device and the head-mounted display device provided in the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0044] According to one aspect of an embodiment of the present application, a coating method for a light-guiding device is provided. The light-guiding device finally produced is, for example, a diffraction light waveguide element, which can be applied to AR optical solutions. The coupling-in region and the coupling-out region of the light-guiding device are both formed with a set film layer.

[0045] It should be noted that the conventional coating method for diffractive optical waveguide components involves masking the outcoupling region after the incoupling and outcoupling regions are fabricated. A metal oxide layer is then formed on the incoupling region. The incoupling region is then masked again, and a non-metallic oxide layer is formed on the outcoupling region. This process involves two masking steps. This design is based on the different requirements for light diffraction behavior in the incoupling and outcoupling regions, resulting in different coatings.

[0046] The method for manufacturing a light guide device provided in an embodiment of the present application includes the following steps:

[0047] Step S1, providing a substrate 100, and forming an incoupling region 101 and an outcoupling region 102 on the substrate 100, see FIG1;

[0048] Step S2: forming a metal layer 200 on the coupling-in region 101 while shielding the coupling-out region 102, and controlling the thickness of the metal layer 200 to be greater than 15 nm, see FIG. 2 ; and

[0049] Step S3 : forming a non-metallic material layer 300 on the substrate 100 without shielding the coupling-in region 101 , and the non-metallic material layer 300 at least covers the coupling-out region 102 .

[0050] According to the coating method for a light-guiding device provided in the above-described embodiment of the present application, by first forming a metal layer 200 of a certain thickness at the location of the coupling-in region 101, when the non-metallic material layer 300 is formed at the location of the coupling-out region 102, the coupling-in region 101 need not be shielded. This is because metal materials have a skin effect. After exceeding their skin depth, the excess thickness of the metal layer 200 will no longer affect the diffraction behavior (diffraction efficiency) of the coupling-in region 101. The design of the metal layer 200 ensures that when the non-metallic material layer 300 is formed on the coupling-out region 102, the coupling-in region 101 does not need to be shielded, effectively reducing the number of steps and lowering production costs.

[0051] That is to say, compared with the traditional diffraction waveguide coating solution, the manufacturing solution provided by the embodiment of the present application does not require the separation area coating operation.

[0052] The solution provided by the embodiment of the present application can eliminate the need for a masking step. The coupling region 101 is formed with a metal layer 200. Due to the skin effect of the metal material, even if a non-metallic material layer 300 is formed on the metal layer 200, the diffraction efficiency will not be affected. This means that the diffraction efficiency requirements for the coupling region 101 can be met, thereby ensuring the optical performance of the light guide device and improving image quality.

[0053] In step S1 , the coupling-in region 101 and the coupling-out region 102 may be arranged in any combination or arrangement on the same surface of the substrate 100 . Alternatively, the coupling-in region 101 and the coupling-out region 102 may be located on different surfaces of the substrate 100 .

[0054] The coupling-in region 101 includes a coupling-in grating.

[0055] The coupling-in grating may be any type of one-dimensional grating or any type of two-dimensional grating. For example, the coupling-in grating in the coupling-in region 101 is a blazed grating.

[0056] The outcoupling region 102 includes an outcoupling grating.

[0057] The outcoupling grating may be any type of one-dimensional grating or any type of two-dimensional grating.

[0058] In step S2, the thickness of the metal layer 200 is designed to be greater than the skin depth of visible light in the metal layer 200, so that after exceeding its skin depth, the excess thickness of the metal layer 200 will no longer affect the diffraction behavior of the coupling grating in the coupling region 101 to visible light.

[0059] Specifically, as shown in FIG2 , a metal layer 200 having a thickness greater than 15 nm is first formed on the coupling region 101 . At this time, based on the skin effect of the material, the diffraction efficiency curve of the coupling region 101 can be seen in FIG3 .

[0060] In step S3, based on the metal layer 200 having a thickness greater than 15 nm having been formed on the coupling-in region 101 in step S2, a non-metallic material layer 300 can be directly formed on the substrate 100 to cover the coupling-out region 102 without masking the coupling-in region 101. In other words, when forming the non-metallic material layer on the coupling-out region 102, the masking process of the coupling-in region 101 can be omitted. In other words, the non-metallic material layer 300 can be directly formed on the substrate 100 without avoiding the coupling-in region 101, which can simplify the process.

[0061] In step S3, since the coupling-in region 101 is not shielded, the non-metallic material layer 300 is directly formed on the substrate 100. In addition to covering the designated coupling-out region 102, the non-metallic material layer 300 also covers the unshielded coupling-in region 101 (see FIG4 ). The non-metallic material layer 300 formed on the coupling-in region 101 is stacked on a certain thickness of the metal layer 200. Due to the skin effect of the metal material, when incident light diffracts in the coupling-in region 101, the efficiency curve of the coupling-in region 101 is shown in FIG5 . Comparing the efficiency curve with the diffraction efficiency curve shown in FIG3 , it can be seen that the two results remain unchanged. This demonstrates that the introduction of the metal layer 200, even with the stacking of the non-metallic material layer 300, does not affect the diffraction performance of the coupling-in region 101.

[0062] Referring to Figure 6 , which illustrates a conventional coating scheme for a light guide device, an input region 101 is formed on a substrate 100. A metal oxide layer, such as a titanium oxide layer 400, is formed on the input region 101. The trend of the diffraction efficiency curve corresponding to the input region 101 can be seen in Figure 7 . Furthermore, if the input region 101 is not shielded, and a non-metallic material layer 300, such as a silicon oxide layer 500, is formed directly on the output region 102 (see Figure 8 ), the diffraction efficiency curve corresponding to the input region 101 is significantly affected (compared to the diffraction efficiency curve shown in Figure 7 ), resulting in a decrease in overall efficiency (see Figure 9 ).

[0063] It should be noted that, in the embodiment of the present application, the non-metallic material layer 300 may be formed on the substrate 100 by coating, and the non-metallic material layer 300 may cover the outcoupling region 102 .

[0064] In some examples of the present application, referring to FIG. 2 , the coupling-in region 101 includes a coupling-in grating, and the structure of the metal layer 200 corresponds to the structure of the coupling-in grating.

[0065] For example, the coupling grating used in the coupling region 101 is a blazed grating. Referring to FIG. 2 , the shape of the metal layer 200 needs to correspond to the structural shape of the blazed grating.

[0066] In order to better integrate the metal layer 200 with the coupling grating, the structural shape of the metal layer 200 should be adapted to the structural shape of the coupling grating.

[0067] It should be noted that the coupling grating is not shown in Figure 2, and only the structural shape of the blazed grating is used as an example to illustrate the structural form of the metal layer 200. That is, a blazed grating is used as the coupling region, and the metal layer 200 is deposited on its surface.

[0068] In some examples of the present application, the thickness of the metal layer 200 is H, and 16 nm ≤ H ≤ 100 nm.

[0069] The coating solution provided in the embodiment of the present application primarily forms a metal layer 200 of a certain thickness at the location of the coupling region 101 to prevent the subsequently formed non-metallic oxide coating from affecting the diffraction efficiency of the coupling region 101. This utilizes the skin effect of metal materials, which imposes certain requirements on the thickness of the metal layer formed of the metal material. Only after exceeding the skin depth will the excess metal layer no longer affect the diffraction behavior of the coupling region.

[0070] The thickness of the metal layer 200 in the coupling region 101 is typically 16 nm to 100 nm, as the thickness of the metal layer is easy to control and process without increasing the thickness of the light guide device.

[0071] For example, the thickness of the metal layer 200 can be designed to be 16 nm, 25 nm, 40 nm, 60 nm, 95 nm, etc. The thickness of the metal layer 200 can be flexibly controlled as needed, and this application does not impose any limitation thereto.

[0072] In some examples of the present application, the material of the metal layer 200 includes aluminum, gold, copper or silver.

[0073] According to the material of the metal layer 200 provided in the above example, aluminum is more preferably used.

[0074] All of the above-mentioned metal materials have skin effect. In practical applications, they can be selected according to needs and costs, and this application does not impose any restrictions on this.

[0075] In some examples of the present application, the metal layer 200 is further covered with the non-metallic material layer 300, see Figure 3; the outcoupling region 102 includes an outcoupling grating and the non-metallic material layer 300 covering the outcoupling grating, and the incoupling grating and the outcoupling grating form a closed grating vector polygon.

[0076] According to the above example, referring to FIG3 , the coupling-in region 101 includes a metal layer 200 and a non-metallic material layer 300 stacked on the coupling-in grating. The coupling-out region 102 includes a non-metallic material layer 300 stacked on the coupling-out grating. The coupling-in region 101 and the non-metallic material layer 300 on the coupling-out region 102 can be formed by coating the substrate 100.

[0077] Referring to FIG1 , an embodiment of the present application provides a light-guiding device having a substrate 100 with an incoupling region 101 and an outcoupling region 102. The incoupling region 101 is used to couple external light into the substrate 100. The outcoupling region 102 can function as a pupil dilator and outcoupling device, expanding the incoupling light from the incoupling region 101 in both the horizontal and vertical dimensions and outcoupling the light.

[0078] The coupling-in grating of the coupling-in region 101 and the coupling-out grating of the coupling-out region 102 need to form a closed grating vector polygon.

[0079] Optionally, the coupling region 101 may be composed of a single one-dimensional or two-dimensional grating or a plurality of one-dimensional or two-dimensional gratings.

[0080] Optionally, the outcoupling region 102 may be composed of a single two-dimensional grating or a plurality of one-dimensional or two-dimensional gratings.

[0081] In some examples of the present application, the metal layer 200 can be formed in the coupling region 101 by a deposition method, and the deposition method includes atomic layer deposition ALD, physical vapor deposition PVD, high temperature gas phase reaction CVD or plasma enhanced chemical vapor deposition PECVD.

[0082] The formation method of the metal layer 200 provided in the above example is conducive to controlling the thickness of the metal layer 200 to be greater than 15 nm.

[0083] In some examples of the present application, the material of the non-metallic material layer 300 includes silicon oxide, titanium oxide, aluminum oxide or embossing glue.

[0084] According to another aspect of the present application, a light guide device is provided, which is manufactured using the above-mentioned coating method for a light guide device.

[0085] According to another aspect of the present application, a light-guiding device is also provided. Referring to FIG1 , the light-guiding device includes a substrate 100, and an in-coupling region 101 and an out-coupling region 102 arranged on the substrate 100; the in-coupling region 101 is covered with at least a metal layer 200; and the out-coupling region 102 is covered with a non-metallic material layer 300.

[0086] The light guide device is, for example, a diffraction light waveguide element, and the substrate 100 is a waveguide substrate.

[0087] The coupling-in region 101 is used to couple external light into the substrate 100 .

[0088] The outcoupling region 102 is a pupil expansion and outcoupling grating, which expands the coupled light from the coupling region 101 in both horizontal and vertical dimensions and couples the light out.

[0089] The coupling-in region 101 and the coupling-out region 102 may be placed on the same surface of the substrate 100 or distributed on different surfaces in any arrangement or combination.

[0090] For the entire light-guiding device, the coupling-in grating in the coupling-in region 101 and the coupling-out grating in the coupling-out region 102 form a closed grating vector polygon. The coupling-in region 101 can be composed of a single one-dimensional or two-dimensional grating or multiple one-dimensional or two-dimensional gratings. The coupling-out region 102 can be composed of a single two-dimensional grating or multiple one-dimensional or two-dimensional gratings.

[0091] According to another aspect of the present application, an embodiment of the present application further provides a head-mounted display device, wherein the head-mounted display device includes a housing and the light guide device as described above.

[0092] The light guide component is, for example, a diffraction light waveguide element, which is disposed in the housing.

[0093] In an embodiment of the present application, the head-mounted display device may be AR glasses or MR glasses, which further includes an image source, which provides incident light for the light guide device. When the incident light is incident from the air medium to the light guide device, it first passes through the diffraction of the coupling-in area 101, then enters the substrate 100, is transmitted by total reflection, and then passes through the coupling-out area 102 and enters the human eye.

[0094] The specific implementation of the head-mounted display device of the embodiment of the present application can refer to the coating method of the above-mentioned light guide device and the various embodiments of the light guide device. Therefore, it has at least all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be repeated here one by one.

[0095] 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.

[0096] Although some specific embodiments of the present application have been described in detail by way of example, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present application. It should be understood by those skilled in the art that the above examples may be modified without departing from the scope and spirit of the present application. The scope of the present application is defined by the appended claims.

Claims

1. A coating method for a light guide device, characterized in that: include: Providing a substrate, and forming a coupling-in region and a coupling-out region on the substrate; Under the condition of shielding the out-coupling region, forming a metal layer on the in-coupling region, and controlling the thickness of the metal layer to be greater than 15 nm; and A non-metal material layer is formed on the substrate without shielding the coupling-in region, and the non-metal material layer at least covers the coupling-out region.

2. The coating method of a light guide device according to claim 1, characterized in that: The coupling-in region includes a coupling-in grating, and the structure of the metal layer corresponds to the structure of the coupling-in grating.

3. The coating method of a light guide device according to claim 1, characterized in that: The thickness of the metal layer is H, and 16nm≤H≤100nm.

4. The coating method of a light guide device according to claim 1, characterized in that: The material of the metal layer includes aluminum, gold, copper or silver.

5. The coating method of a light guide device according to claim 2, characterized in that: The metal layer is also covered with the non-metal material layer; The out-coupling region includes an out-coupling grating and the non-metal material layer covering the out-coupling grating, and the in-coupling grating and the out-coupling grating form a closed grating vector polygon.

6. The coating method for a light guide device according to any one of claims 1 to 5, characterized in that: The metal layer is formed in the coupling-in region by a deposition method, wherein the deposition method includes atomic layer deposition ALD, physical vapor deposition PVD, high temperature gas phase reaction CVD or plasma enhanced chemical vapor deposition PECVD.

7. The coating method of a light guide device according to claim 1, characterized in that: The material of the non-metal material layer includes silicon oxide, titanium oxide, aluminum oxide or embossing glue.

8. A light guide device, characterized in that: The light guide device is manufactured by the coating method of any one of claims 1 to 7.

9. A light guide device, characterized in that: It comprises a substrate (100), and a coupling-in region (101) and a coupling-out region (102) arranged on the substrate (100); The coupling region (101) is at least covered with a metal layer (200); The outcoupling region (102) is covered with a non-metal material layer (300).

10. A head mounted display device, characterized in that: include: a housing; and A light guiding device as claimed in claim 8 or 9.

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