Optical display module and head-mounted device

Abstract

Provided in the present application are an optical display module and a head-mounted device. The optical display module comprises an optical engine, a diffractive waveguide layer, a sealing member and a reflecting film, wherein the optical engine and the diffractive waveguide layer are opposite each other and have a gap therebetween; the sealing member is arranged between the optical engine and the diffractive waveguide layer and connected to both the optical engine and the diffractive waveguide layer; and the reflecting film is arranged on the diffractive waveguide layer, and at least part of the reflecting film is located between the sealing member and a total-reflection propagation region of the diffractive waveguide layer, thus separating the sealing member from the total-reflection propagation region. By means of the reflecting film, the sealing member is prevented from coming into direct contact with the total-reflection propagation region of the diffractive waveguide layer, thereby ensuring light guide efficiency; moreover, providing an internal protection layer on the diffractive waveguide layer is unnecessary, enabling the thickness and weight to be reduced.

Description

Optical display modules and head-mounted devices Technical Field

[0001] The present application belongs to the field of augmented reality technology, and specifically relates to an optical display module and a head-mounted device. Background Art

[0002] The optical module of an augmented reality (AR) near-eye display device usually consists of two parts: an optical engine (or light engine) and an optical combiner. The optical engine consists of an image source and a projection lens. The image source is used to generate the image to be displayed, and the projection lens projects the image displayed by the image source to infinity or a specified distance. The optical combiner can transmit the signal light emitted by the optical engine in a directionally directed manner to the human eye, forming the image to be displayed on the retina. At the same time, the optical combiner has good transmittance to the ambient light in the real world. Through the optical combiner, the human eye can clearly see the real-world scenery and the image projected by the optical engine at the same time. Diffraction optical waveguides are the preferred solution for optical combiners due to their thin thickness, light weight and good light transmittance.

[0003] A diffraction waveguide typically consists of several diffraction waveguide layers, at least one protective layer, and adhesive bonding the diffraction waveguide layers to the protective layer. Each diffraction waveguide layer is provided with an in-coupling grating and an out-coupling grating. The in-coupling grating couples light from the light engine into the diffraction waveguide layer, where it undergoes total internal reflection. After total internal reflection within the diffraction waveguide layer, the light is transmitted to the out-coupling grating, which diffracts the light within the diffraction waveguide layer into free space. Once in the eye, the light forms a virtual image on the retina to be displayed. In addition to the in-coupling and out-coupling gratings, each diffraction waveguide layer may also be provided with a turning grating to achieve requirements such as pupil expansion.

[0004] When the diffraction waveguide is assembled with the light engine, a gap inevitably exists between them due to structural design and other reasons. If the AR optical display module is used directly without sealing this gap, impurities such as dust and water vapor will inevitably enter this gap during use or reliability testing. This will cause the light emitted by the light engine to be scattered by dust and water vapor, affecting the clarity of the virtual image displayed by the entire AR optical display module. Even when a large amount of dust accumulates in the gap, the light emitted by the light engine will be blocked by the accumulated dust, and the light flux entering the diffraction waveguide will decrease, which in turn will cause the image brightness of the virtual image displayed by the AR display module to decrease. It can be seen that if this gap is not sealed, it will affect the quality of the virtual image displayed by the AR display module.

[0005] To seal this gap, existing techniques use sealants to secure the light engine and diffractive waveguide, thereby sealing gap C. As shown in Figure 1 , in the first case, sealant 2 is secured to inner protective layer 3. While this does not affect total internal reflection propagation in diffractive waveguide layer 4 and can seal gap C, the presence of inner protective layer 3 increases the thickness and weight of the diffractive waveguide. As shown in Figure 2 , in the second case, sealant 2 is secured directly to diffractive waveguide layer 4. While this reduces the thickness and weight of the diffractive waveguide, it disrupts total internal reflection propagation in diffractive waveguide layer 4, reducing performance indicators such as optical efficiency and contrast.

[0006] Summary of the Invention

[0007] The technical problem solved by the present application is: how to ensure the light guiding efficiency of the diffraction light waveguide while reducing the thickness and weight of the diffraction light waveguide when assembling and sealing the diffraction light waveguide and the light engine.

[0008] The present application discloses an optical display module, which includes an optical engine, a diffraction waveguide layer, a seal, and a reflective film. The optical engine and the diffraction waveguide layer are opposite to each other with a gap therebetween. The seal is arranged between the optical engine and the diffraction waveguide layer and is connected to the optical engine and the diffraction waveguide layer, respectively. The reflective film is arranged on the diffraction waveguide layer, and at least a portion of the reflective film is located between the seal and the total reflection propagation area of ​​the diffraction waveguide layer, so that the seal is separated from the total reflection propagation area.

[0009] Optionally, the optical display module further includes a fixing member, the fixing member is connected to the optical engine, and the sealing member is connected to the fixing member.

[0010] Optionally, the reflective film includes a single-layer or multi-layer reflective layer.

[0011] Optionally, the reflective film further includes a protective layer, and the protective layer is arranged on the reflective layer.

[0012] Optionally, the optical display module further includes a transparent film layer, which is arranged on the surface of the diffraction waveguide layer close to the optical machine; the reflective film is arranged on the outer surface of the transparent film layer close to the optical machine, or the reflective film is arranged between the transparent film layer and the diffraction waveguide layer.

[0013] Optionally, the reflective film has multiple reflective regions, and the reflectivity of each reflective region is different.

[0014] Optionally, the sealing member is an adhesive.

[0015] Optionally, the coupling-in grating of the diffraction waveguide layer is a reflection grating, and the coupling-in grating is arranged on a surface of the diffraction waveguide layer away from the optical engine.

[0016] Optionally, the coupling-in grating of the diffraction waveguide layer is a transmission grating, and the coupling-in grating is arranged on a surface of the diffraction waveguide layer close to the optical engine.

[0017] The present application also provides a head-mounted device, which includes the above-mentioned optical display module.

[0018] The optical display module and head-mounted device provided in this application have the following technical effects:

[0019] A reflective film is provided on the diffraction waveguide layer to prevent the seal from directly contacting the total reflection propagation area of ​​the diffraction waveguide layer, thereby ensuring light guiding efficiency. At the same time, there is no need to provide an inner protective layer on the diffraction waveguide layer, thereby reducing the thickness and weight of the diffraction waveguide. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG1 is a schematic diagram of an assembly of a light engine and a diffraction light waveguide in the prior art;

[0021] FIG2 is a schematic diagram of an assembly of an optical engine and a diffractive optical waveguide in another prior art;

[0022] FIG3 is a schematic diagram of an optical display module according to one or more embodiments;

[0023] FIG4 is a schematic diagram of an optical display module according to one or more embodiments;

[0024] 5A, 5B, and 5C are top views of diffraction waveguide layers having reflective films of different shapes according to one or more embodiments;

[0025] FIG6 is a top view of a diffraction waveguide layer having a turn grating according to one or more embodiments;

[0026] FIG7 is a schematic diagram of the composition of a reflective film according to one or more embodiments;

[0027] 8A and 8B are top views of a diffraction waveguide layer when a reflective film has a plurality of reflective regions according to one or more embodiments;

[0028] FIG9 is another schematic diagram of the composition of a reflective film according to one or more embodiments;

[0029] FIG10 is a schematic diagram of a partial structure of an optical display module according to one or more embodiments;

[0030] FIG11 is a schematic diagram of an optical display module having two diffractive waveguide layers according to one or more embodiments;

[0031] FIG12 is a schematic diagram of an optical display module having two diffractive waveguide layers and an outer protective layer according to one or more embodiments;

[0032] FIG. 13 is a schematic diagram of an optical display module according to one or more embodiments.

[0033] The correspondence between the reference numerals and component names is as follows:

[0034] 10-optical engine, 20-diffraction waveguide layer, 21-coupling grating, 22-coupling grating, 23-turning grating, 30-sealing element, 40-reflective film, 41-reflective layer, 42-protective layer, 43-adhesive layer, 50-transparent film layer, 60-outer protective layer, 70-fixing element. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of this application more clearly understood, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0036] Before describing the various embodiments of the present application in detail, the technical concept of the present application is briefly described first: In the prior art, when sealing and assembling a diffraction waveguide and an optical machine, if the sealant is directly in contact with the diffraction waveguide layer, the total reflection propagation process in the diffraction waveguide layer will be destroyed, reducing the light guiding efficiency. If an inner protective layer is provided outside the diffraction waveguide layer and the sealant is connected to the inner protective layer, the thickness and weight of the diffraction waveguide will be increased. To this end, the present application provides an optical display module, in which a reflective film is provided on the diffraction waveguide layer. The reflective film is used to prevent the sealant from directly contacting the total reflection propagation area of ​​the diffraction waveguide layer, thereby ensuring light guiding efficiency. At the same time, there is no need to provide an inner protective layer on the diffraction waveguide layer, reducing the thickness and weight. In addition, the comprehensive optical performance of the diffraction waveguide layer, including display uniformity, MTF (Modulation Transfer Function) and contrast, is not affected.

[0037] Specifically, as shown in Figure 3, the optical display module of the first embodiment includes an optical engine 10, a diffraction waveguide layer 20, a seal 30 and a reflective film 40. The optical engine 10 and the diffraction waveguide layer 20 are opposite to each other and have a gap. The seal 30 is arranged between the optical engine 10 and the diffraction waveguide layer 20 and is respectively connected to the optical engine 10 and the diffraction waveguide layer 20. The reflective film 40 is arranged on the diffraction waveguide layer 20, and at least a portion of the reflective film 40 is located between the seal 30 and the total reflection propagation area of ​​the diffraction waveguide layer 20, so that the seal 30 is spaced from the total reflection propagation area to prevent the seal 30 from destroying the light guiding process of the total reflection propagation area.

[0038] Exemplarily, the total reflection propagation area is the light transmission area between the coupling-in grating 21 and the coupling-out grating 22 of the diffraction waveguide layer 20. The dotted area A in FIG5A , the dotted area B in FIG5B , and the dotted area C in FIG5C can all represent the total reflection propagation area. The reflective film 40 can be located entirely within the total reflection propagation area, or a portion of the reflective film 40 can be located within the total reflection propagation area. In other embodiments, if a turning grating 23 is provided on the surface of the diffraction waveguide layer 30 in addition to the coupling-in grating 21 and the coupling-out grating 22, that is, the turning grating 23 is provided between the coupling-in grating 21 and the coupling-out grating 22, the total internal reflection propagation area in this case can be defined as the light transmission area between the coupling-in grating 21 and the coupling-out grating 23. For example, the dotted area D in FIG6 can represent the total internal reflection propagation area. The light introduced through the coupling-in grating 21 passes through the total internal reflection propagation area and reaches the turning grating 23. The turning grating 23 deflects the light and guides the light to the coupling-out grating 22. Finally, the light is projected from the coupling-out grating 22 to the human eye.

[0039] Furthermore, at least a portion of the seal 30 (partial structure or overall structure) abuts against the reflective film 40, and the reflective film 40 separates the seal 30 from the diffraction waveguide layer 20, so that the seal 30 does not directly contact the total reflection propagation area on the diffraction waveguide layer 20.

[0040] Furthermore, to ensure that light from the optical engine 10 can illuminate the coupling-in grating 21, the seal 30 needs to be arranged around the gap between the optical engine 10 and the diffraction waveguide layer 20 to prevent the seal 30 from blocking the light generated by the optical engine 10. At the same time, the coupling-in grating 21 is arranged relative to the optical engine 10. When the coupling-in grating 21 receives the light emitted by the optical engine 10 and then transmits it through total internal reflection, the total internal reflection propagation area will inevitably come into direct contact with the seal 30. In other words, at least part of the structure of the seal 30 will overlap with the total internal reflection propagation area. If no measures are taken, the direct contact of the seal 30 will affect the light guiding process in the total internal reflection propagation area. Therefore, by providing a reflective film 40 between at least part of the structure of the seal 30 and the total internal reflection propagation area, direct contact between the seal 30 and the total internal reflection propagation area is avoided, thereby ensuring light guiding efficiency and ensuring that the comprehensive optical performance of the diffraction waveguide layer, including display uniformity, MTF, and contrast, is not affected. In fact, the total reflection at the contact point between the reflective film 40 and the total reflection propagation area will also be affected. The reflection effect of the reflective film 40 can return the light to the total reflection propagation area, thereby offsetting the effect.

[0041] Exemplarily, the in-coupling grating 21 and the out-coupling grating 22 of the diffraction waveguide layer 20 are both reflective gratings. In this case, the in-coupling grating 21 and the out-coupling grating 22 are both disposed on the surface of the diffraction waveguide layer 20 away from the optical engine 10, that is, the in-coupling grating 21 and the out-coupling grating 22 are both disposed on the inner surface of the diffraction waveguide layer 20. The reflective grating may be a reflective surface relief grating or a reflective volume holographic grating. In other embodiments, as shown in FIG4 , the in-coupling grating 21 of the diffraction waveguide layer 20 may be a transmission grating. In this case, the in-coupling grating 21 is disposed on the surface of the diffraction waveguide layer 20 close to the optical engine 10, that is, the in-coupling grating 21 is disposed on the outer surface of the diffraction waveguide layer 20.

[0042] Furthermore, the position, shape, and area of ​​the reflective film 40 can be set according to actual needs, and factors such as the location and size of the seal to be set should be considered. In order for light to smoothly enter the coupling-in grating 21 and exit from the coupling-out grating 22, the reflective film 40 needs to avoid blocking the coupling-in grating 21 and the coupling-out grating 22. The reflective film 40 can be set around or adjacent to the coupling-in grating 21. For example, as shown in FIG5A , the reflective film 40 is in the shape of a circular ring and is arranged around the coupling-in grating 21; as shown in FIG5B , the reflective film 40 is in the shape of a semicircular ring and is arranged around the coupling-in grating 21; and as shown in FIG5C , the reflective film 40 is in the shape of a rectangle and is arranged adjacent to the coupling-in grating 21.

[0043] Specifically, as shown in Figures a and b of Figure 7 , the reflective film 40 includes a single or multiple reflective layers 41. The reflective layer 41 can be a metal reflective layer, a dielectric reflective layer, or a combination of these. The reflectivity of the reflective layer 41 in the visible light band can be adjusted as needed. In one or more embodiments, the reflectivity of the reflective layer 41 in the visible light band is greater than 95%.

[0044] In another embodiment, the reflective film 40 has multiple reflective regions, each with a different reflectivity, to further enhance the display uniformity of the diffraction waveguide. Within the diffraction waveguide layer, light energy loss varies along different light transmission paths, resulting in uneven intensity of the light ultimately emitted from the outcoupling grating. Specifically, the intensity of the light emitted from some outcoupling regions is lower than that from other regions. At least a portion of the reflective film 40 is located along the light transmission path of the diffraction waveguide layer. Therefore, the light intensity can be adjusted by providing reflective regions with different reflectivities on the reflective film 40. For example, a reflective region with lower reflectivity can be provided on a shorter light transmission path, while a reflective region with higher reflectivity can be provided on a longer light transmission path. For example, as shown in FIG8A , the reflective film 40 has six reflective regions with different reflectivities: R1, R2, R3, R4, R5, and R6. As shown in FIG8B , the reflective film 40 has three reflective regions with different reflectivities: R1, R2, and R3. It should be noted that the number, shape and reflectivity of the reflective regions on the reflective film 40 are all set to achieve the requirement of improving the display uniformity of the diffraction light waveguide, and are not particularly limited in this embodiment.

[0045] Furthermore, as shown in a and b in FIG7 , the reflective film 40 further includes a protective layer 42, which is disposed on the reflective layer 41. The protective layer 42 can be disposed on one or both sides of the reflective layer 41 to prevent corrosion from external air and the outgassing effect of the diffraction waveguide layer 20 (outgassing refers to the slow release of water vapor absorbed in the resin over time when the waveguide substrate is a resin material. Without the protective layer, water vapor may corrode the reflective layer). ， This results in a decrease in the performance or reliability of the reflective layer. The number of protective layers 42 can be set according to actual needs.

[0046] For example, the reflective film 40 may be prepared by physical vapor deposition (PVD), chemical vapor deposition (CVD), spraying, dipping, printing, laminating, etc. The preparation process of the reflective film 40 is described below using the laminating process as an example.

[0047] Specifically, as shown in Figure 9 , the reflective film 40 is composed of a reflective layer 41, an adhesive layer 43, and a protective layer 42. The reflective layer 41 and protective layer 42 are prefabricated sheet materials. The prefabricated sheet materials 41 and 42 are then cut into predetermined shapes as needed and then bonded to the diffractive waveguide layer 20 via the adhesive layer 43. Exemplarily, the adhesive layer 43 is made of a transparent adhesive material, preferably a transparent sheet of OCA (which may also be OCR adhesive). The reflective layer 41 and the protective layer 42 can be a complete sheet during the prefabrication process. In this case, the reflective layer 41 and the protective layer 42 are already bonded together during the prefabrication process. In the prefabrication process, the reflective layer 41 and the protective layer 42 can also be prefabricated as separate sheets. When preparing the diffraction waveguide, the reflective layer 41 is first connected to the diffraction waveguide layer 20 via the adhesive layer 43, and then the protective layer 42 is connected to the reflective layer 41 (in this case, the adhesive layer 43 needs to be provided between the protective layer 42 and the reflective layer 41).

[0048] Furthermore, the optical display module also includes a transparent film layer 50, which is disposed on the surface of the diffraction waveguide layer 20 near the optical engine 10. As shown in Figure 10, the reflective film 40 is disposed on the outer surface of the transparent film layer 50 near the optical engine 10. In another embodiment, the reflective film 40 is disposed between the transparent film layer 50 and the diffraction waveguide layer 20, that is, the reflective film 40 is disposed on the inner surface of the transparent film layer 50 away from the optical engine 10. Optionally, the transparent film layer 50 includes at least one of a hardening layer, an anti-reflection layer, and an anti-fingerprint layer. When the transparent film layer 50 includes at least two of the hardening layer, the anti-reflection layer, and the anti-fingerprint layer, the reflective film 40 may also be disposed between two different layers of the transparent film layer 50, for example, between the hardening layer and the anti-reflection layer.

[0049] Furthermore, the optical display module also includes an outer protective layer 60, which is arranged on the side of the diffraction waveguide layer 20 away from the optical machine 10, and the outer protective layer 60 and the diffraction waveguide layer 20 are spaced apart to form an air layer therebetween, thereby ensuring the full reflection propagation of the diffraction waveguide layer 20 and protecting the diffraction waveguide layer 20.

[0050] As shown in FIG11 , in one embodiment, the number of diffraction waveguide layers 20 can be two, with the diffraction waveguide layers 20 spaced apart and an air layer formed between them. The in-coupling grating 21 and out-coupling grating 22 of the outermost diffraction waveguide layer 20 in FIG11 are both transmission gratings and are disposed on the inner surface of the diffraction waveguide layer 20 . The in-coupling grating 21 and out-coupling grating 22 are not exposed to the external environment, and therefore, an outer protective layer 60 is not required on the outer side of the diffraction waveguide layer 20 . As shown in FIG12 , in another embodiment, when there are two diffraction waveguide layers 20, the coupling-in grating 21 and the coupling-out grating 22 of the outermost diffraction waveguide layer 20 are both reflective gratings and are disposed on the outer surface of the diffraction waveguide layer 20. In this case, the coupling-in grating 21 and the coupling-out grating 22 are exposed to the external environment. Therefore, an outer protective layer 60 may be disposed on the outer side of the outermost diffraction waveguide layer 20. That is, from the inside to the outside, the first diffraction waveguide layer 20, the second diffraction waveguide layer 20, and the outer protective layer 60 are sequentially disposed to protect the coupling-in grating 21 and the coupling-out grating 22 on the outermost diffraction waveguide layer 20. The inner surface herein refers to the surface of the diffraction waveguide layer 20 facing the optical engine 10, the outer surface refers to the surface of the diffraction waveguide layer 20 facing away from the optical engine 10, and the outer side herein refers to the side of the diffraction waveguide layer 20 facing away from the optical engine 10. In other embodiments, the number of diffraction waveguide layers 20 may be three or more, and the specific number can be set according to actual needs. In summary, in the case of multiple diffraction waveguide layers 20, when the outer surface of the outermost diffraction waveguide layer 20 is provided with at least one of the coupling-in grating 21, the coupling-out grating 22, and the turning grating, an outer protective layer needs to be provided on the outer side of the outermost diffraction waveguide layer 20 to protect the grating.

[0051] As shown in FIG13 , in another embodiment, the optical display module further includes a fixing member 70, which is connected to the optical engine 10, and the sealing member 30 is connected to the fixing member 70. Exemplarily, the fixing member 70 is a cylinder, and the fixing member 70 is disposed on the periphery of the optical engine 10.

[0052] In one or more embodiments, the sealing member 30 is an adhesive. During assembly, the adhesive is first applied around the coupling grating 21 of the diffraction waveguide layer 20, where a reflective film 40 is pre-formed. The adhesive is partially applied to the reflective film 40. The optical engine 10 or the fixture 70 is then adhered to the adhesive. This seals the gap between the optical engine 10 and the diffraction waveguide layer 20 and secures the optical engine 10. In other embodiments, the adhesive can also be applied to corresponding locations on the optical engine 10 or the fixture 70, so that the optical engine 10 or the fixture 70 is adhered to the diffraction waveguide layer 20 and the reflective film 40.

[0053] The optical display module disclosed in the first embodiment uses a reflective film to prevent direct contact between the seal and the total reflection propagation area of ​​the diffraction waveguide layer, thereby ensuring light guiding efficiency. At the same time, there is no need to provide an inner protective layer on the diffraction waveguide layer, thereby reducing thickness and weight.

[0054] The second embodiment also discloses a head-mounted device, which includes the optical display module in the first embodiment. The head-mounted device can reduce the weight of the device while ensuring the light guiding efficiency, which is conducive to miniaturization design.

[0055] The head-mounted device can be an augmented reality device, such as augmented reality glasses. In the example of augmented reality glasses, the head-mounted device can be configured to transmit data to and receive data from an external processing device via a signal connection, which can be a wired connection, a wireless connection, or a combination thereof. However, in other cases, the head-mounted device can be used as a standalone device, i.e., data processing is performed on the head-mounted device itself. The signal connection can be configured to carry any type of data, such as image data (e.g., still images and / or full motion video, including 2D and 3D images), audio, multimedia, voice, and / or any other type of data. The external processing device can be, for example, a game console, a personal computer, a tablet computer, a smartphone, or other type of processing device. The signal connection can be, for example, a universal serial bus (USB) connection, a Wi-Fi connection, a Bluetooth or Bluetooth Low Energy (BLE) connection, an Ethernet connection, a cable connection, a DSL connection, a cellular connection (e.g., 3G, LTE / 4G, or 5G), or the like, or a combination thereof. Additionally, the external processing device may communicate with one or more other external processing devices via a network, which may be or include, for example, a local area network (LAN), a wide area network (WAN), an intranet, a metropolitan area network (MAN), the global Internet, or a combination thereof.

[0056] It should be noted that it is understandable that a complete augmented reality glasses should also have other necessary basic components, but the other components are not the focus of this embodiment, so they are not shown in the drawings and are not described in detail in the specification, and these components are well-known technologies to those skilled in the art.

[0057] The above describes in detail the specific implementation methods of the present application. Although some embodiments have been shown and described, those skilled in the art should understand that these embodiments can be modified and improved without departing from the principles and spirit of the present application, the scope of which is defined by the claims and their equivalents. These modifications and improvements should also be within the scope of protection of the present application.

Claims

1. An optical display module, wherein: The optical display module includes an optical machine, a diffraction waveguide layer, a seal and a reflective film. The optical machine and the diffraction waveguide layer are opposite to each other and have a gap therebetween. The seal is disposed between the optical machine and the diffraction waveguide layer and are respectively connected to the optical machine and the diffraction waveguide layer. The reflective film is disposed on the diffraction waveguide layer, and at least a portion of the reflective film is located between the seal and a total reflection propagation region of the diffraction waveguide layer, so that the seal is spaced from the total reflection propagation region.

2. The optical display module according to claim 1, wherein: The optical display module further includes a fixing member, wherein the fixing member is connected to the optical machine, and the sealing member is connected to the fixing member.

3. The optical display module according to claim 1, wherein: The reflective film includes a single-layer or multi-layer reflective layer.

4. The optical display module according to claim 3, wherein: The reflective film further includes a protective layer, and the protective layer is disposed on the reflective layer.

5. The optical display module according to claim 3, wherein: The optical display module also includes a transparent film layer, which is arranged on the surface of the diffraction waveguide layer close to the optical machine; the reflective film is arranged on the outer surface of the transparent film layer close to the optical machine, or the reflective film is arranged between the transparent film layer and the diffraction waveguide layer.

6. The optical display module according to claim 1, wherein: The reflective film has a plurality of reflective regions, and the reflectivities of the reflective regions are different.

7. The optical display module according to claim 1, wherein: The sealing member is an adhesive.

8. The optical display module according to claim 1, wherein: The coupling-in grating of the diffraction waveguide layer is a reflection grating, and the coupling-in grating is arranged on the surface of the diffraction waveguide layer away from the optical engine.

9. The optical display module according to claim 1, wherein: The coupling-in grating of the diffraction waveguide layer is a transmission grating, and the coupling-in grating is arranged on the surface of the diffraction waveguide layer close to the optical engine.

10. A head mounted device, wherein: The head-mounted device comprises the optical display module according to any one of claims 1 to 9.

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