Diffractive optical waveguide, waveguide support dot lattice structure and method of manufacturing the same

Abstract

The application relates to a diffraction optical waveguide, a waveguide support dot array structure and a preparation method thereof. The preparation method comprises the following steps: filling a solidifiable ink in an injection space of a mold, the injection space comprising an outer layer space and a plurality of concave dot spaces arranged at intervals on the inner side; attaching and abutting the protective cover plate and the mold by making the first side of the protective cover plate correspond to the injection space; starting the solidification process of the solidifiable ink; and demolding the protective cover plate from the mold after the solidification process is completed, so that the first side of the protective cover plate forms an integrated first hardening layer and a plurality of convex dots. After the scheme of the application is adopted, the one-time and integrated transfer preparation of the hardening layer and the support dot array on one side of the protective cover plate can be realized at the same time, the support dot array and the hardening layer support each other and are integrated and linked, so that the mechanical strength of the support dot array can be effectively improved, and the pressure resistance and reliability of the support dot array are improved.

Description

Technical Field

[0001] This application relates to the field of near-eye display technology, and in particular to a diffractive waveguide, a waveguide support lattice structure, and a method for fabricating the same. Background Technology

[0002] Augmented Reality (AR) technology, as a core technology for next-generation human-computer interaction, has been widely applied in consumer electronics, industrial manufacturing, healthcare, and military training in recent years. Diffractive waveguides, with their advantages of being thin, light-weight, having a large field of view, and high light transmittance, have become the core display optical solution for mainstream AR glasses. Diffractive waveguide lenses (waveguide sheets) typically consist of a transparent substrate and a diffraction grating structure fabricated on its surface. Through the diffraction and total internal reflection effects of the grating structure and the substrate, images can be projected onto the pupil of the human eye.

[0003] However, diffraction grating structures are extremely fragile, and their surface microstructures are highly susceptible to environmental influences: dust and moisture in the air can adhere to the grating surface, reducing diffraction efficiency; physical contact can cause scratches and breakage of the grating, directly resulting in bright spots, dark spots, or even complete failure in the display area. Therefore, the industry commonly uses a transparent protective cover plate attached to the waveguide grating side (i.e., the side of the substrate where the grating structure is fabricated, i.e., the grating side of the waveguide sheet) to physically protect the grating structure. This protective cover plate not only isolates the grating from external environmental erosion and damage but also maintains an air-medium environment on the grating side. The refractive index difference between air and the waveguide substrate is a necessary condition for the normal operation of the diffraction grating.

[0004] In practical applications, controlling the gap between the protective cover and the waveguide sheet becomes a key factor affecting display performance. According to the principle of optical thin-film interference, when an air film of thickness *d* exists between two parallel transparent surfaces, incident light will interfere after reflection from both surfaces. When the air gap *d* is less than a certain distance, the spacing of the interference fringes will exceed the minimum resolution of the human eye, forming concentric rings of alternating light and dark or colored patterns visible to the naked eye—the Newton's rings effect. The Newton's rings effect severely reduces the contrast and clarity of AR displays, causing image ghosting and color distortion, greatly impacting the user's visual experience. Even if the overall average gap is greater than a certain distance, if there is unevenness in the gaps in certain areas, Newton's rings defects will still occur in the corresponding regions.

[0005] To address these issues, relevant technologies typically incorporate a support medium between the protective cover and the waveguide sheet. This support medium precisely controls the minimum gap between the two, ensuring that the gap is greater than a predetermined distance and is uniform. Currently, a common industry solution involves fabricating a support lattice on the protective cover or on a hardened surface of the protective cover. These support lattices serve as a support structure, maintaining a stable air gap between the protective cover and the waveguide sheet.

[0006] To avoid impacting the optical display effect and aesthetics, the parameters of the support dot matrix are strictly limited. For example, the diameter of the support dot matrix typically needs to be less than 80μm, and the spacing between the dots needs to be greater than 500μm to ensure that individual dots are invisible to the human eye and do not significantly obstruct or scatter the display light. However, these parameter limitations directly result in low mechanical strength of the support dot matrix. When the protective cover is subjected to external pressure, drop impact, or thermal stress caused by temperature changes, or when subjected to repeated external forces, the dot matrix is ​​prone to breakage, tilting, or deformation. Especially in the daily use of consumer-grade AR glasses, users often accidentally press on the lens surface. After repeated pressing, the supporting function of the support dot matrix quickly fails, resulting in excessively small local gaps and thus Newton's rings defects.

[0007] The aforementioned shortcomings urgently require improvement or resolution by those skilled in the art. Summary of the Invention

[0008] In view of this, the embodiments of this application aim to provide a diffractive waveguide, a waveguide support lattice structure and a method for fabricating the same, which can effectively improve the mechanical strength of the waveguide support lattice and enhance its compressive strength and reliability.

[0009] In a first aspect, the waveguide lattice support structure fabrication method provided in this application includes the following steps: filling a mold with curable ink in the injection space, the injection space including an outer layered space and an inner space with multiple recessed points spaced apart from each other; aligning the first side of a protective cover plate with the injection space, so that the protective cover plate and the mold are attached and pressed together; initiating the curing process of the curable ink; and after the curing process is completed, demolding the protective cover plate from the mold, so that the first side of the protective cover plate forms an integrated first hardening layer and multiple protrusions.

[0010] Secondly, the waveguide support lattice structure provided in this application includes a protective cover plate and an integrated first hardening layer and a plurality of protrusions disposed on a first side of the protective cover plate; the waveguide support lattice structure is prepared by the waveguide lattice support structure preparation method described above.

[0011] Thirdly, the diffractive optical waveguide provided in this application includes a waveguide sheet and the waveguide support lattice structure described above, wherein the first side of the protective cover plate is disposed on the diffractive optical unit side of the waveguide sheet.

[0012] After implementing the scheme of this application embodiment, the hardening layer and the support dot matrix (multiple bumps) can be fabricated in one step and integrally on one side of the waveguide protection cover. Specifically, a curable ink is filled into a pre-set injection space on the mold. The injection space includes an outer layered space and a plurality of recessed spaces spaced apart from each other on the inner side. Then, the first side of the protection cover is aligned with the injection space, so that the protection cover and the mold are attached and pressed together. Then, the curing process of the curable ink is started. Finally, after the curing process is completed, the protection cover is demolded from the mold, so that the first side of the protection cover forms an integral first hardening layer and multiple bumps (the multiple bumps form the support dot matrix). Therefore, compared with related technologies that print and prepare the support lattice on the surface of the protective cover plate or the hardened surface of the protective cover plate, this application can simultaneously achieve one-time, integrated transfer preparation of the hardened layer and the support lattice on one side of the protective cover plate. The support lattice and the hardened layer support each other and work together as a whole. The support lattice, the hardened layer, and the protective cover plate cooperate with each other, thus effectively improving the mechanical strength of the support lattice, enhancing its compressive strength and reliability, and avoiding the Newton's rings effect defect caused by the support lattice failing too quickly due to the supporting effect. In addition, compared with related technologies, the one-time preparation of the integrated hardened layer and support lattice also improves the preparation efficiency of the waveguide support lattice structure (including the structure of the protective cover plate, the hardened layer, and the support lattice).

[0013] For further technical effects of the various implementation methods of this application, please refer to the relevant descriptions in the specific embodiments. Attached Figure Description

[0014] Figure 1 A schematic diagram of a waveguide support lattice scheme fabricated using a common printing method, provided for related technologies; Figure 2 This is a basic flowchart of a waveguide-supported lattice structure fabrication method provided in an embodiment of this application. The figure also shows the mold pre-processing and subsequent related process steps of the waveguide-supported lattice structure. Figure 3 for Figure 2 The diagram shows a schematic of the waveguide-supported lattice structure prepared by the method shown. The diagram also shows a schematic of the mold structure and a schematic of the demolding process.

[0015] Figure label: 1. Bump 2 First hardening layer 3. Protective cover plate 4 Second hardening layer 5. Mold 51 Layered Space 52 concave space Detailed Implementation To make the objectives, solutions, and advantages of this application clearer, the technical solutions of the embodiments of this application will be described in detail below with reference to the accompanying drawings. It should be understood that the embodiments described below are only some embodiments of this application, and not all of them; other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are all within the scope of protection of this application. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be arbitrarily combined with each other.

[0016] See one scheme for a waveguide-supported lattice structure in related technologies. Figure 1 As shown, in this scheme, a first hardening layer 2 and a second hardening layer 4 are first processed on both sides of the protective cover plate 3, and then multiple bumps 1 are printed on the surface of the first hardening layer 2 to form a support dot matrix. Due to the need to consider the influence of optical display effect and appearance, the parameters of the support dot matrix are strictly limited, resulting in low mechanical strength of the support dot matrix. When the protective cover plate is subjected to external pressure, drop impact, or thermal stress caused by temperature changes, or when subjected to multiple external forces, the dot matrix is ​​very prone to breakage, tilting, or deformation. Especially in the daily use of consumer-grade AR glasses, users often accidentally press on the lens surface. After repeated pressing, the supporting effect of the support dot matrix will quickly fail, resulting in excessively small local gaps, which in turn causes the waveguide display to produce the Newton's rings effect.

[0017] Based on this, the embodiments of this application aim to provide an innovative solution to specifically solve or improve the above-mentioned problems. Specifically, the embodiments of this application provide a method for fabricating a waveguide lattice support structure, a waveguide support lattice structure, and a diffractive optical waveguide. For ease of understanding and explanation, the following description focuses on the implementation method of the waveguide lattice support structure fabrication method, while other aspects are supplemented and extended based on this description.

[0018] Please refer to Figure 2 and combined Figure 3 The waveguide lattice support structure fabrication method of this application embodiment may include steps S1, S2, S3 and S4.

[0019] Step S1: Mold Injection. Specifically, curable ink can be filled into the injection space of mold 5. The injection space of mold 5 may include an outer layered space 51 and an inner layer of spaced-apart recesses 52, which are connected to each other. The layered space 51 can be used to prepare the first hardening layer 2 of the waveguide lattice support structure, and the spaced-apart recesses 52 can be used to prepare the multiple protrusions 1 of the waveguide lattice support structure. In practice, the curable ink can be filled into the injection space of mold 5 by coating, that is, the curable ink is uniformly coated into the injection space of the mold.

[0020] Step S2: Alignment and pressing. Specifically, after filling the injection space of mold 5 with transparent curable ink, the first side of protective cover 3 ( Figure 3 The top side of the protective cover 3 corresponds to the injection space, and the protective cover 3 and the mold are attached and pressed tightly together. In specific implementation, the mold 5 can be placed on a horizontal base with the injection space of the mold 5 facing upward. After applying the curable ink, the first side of the protective cover 3 is aligned with the injection space downward and then the protective cover 3 is placed on the mold 5, so that the protective cover 3 is attached to the mold 5. Then, the second side of the protective cover 3 is rolled downward by rollers, so that the protective cover 3 is pressed tightly against the mold 5. The curable ink between the protective cover 3 and the mold 5 is squeezed into a uniform thickness and spread between the protective cover 3 and the mold 5, filling all the concave spaces 52 and layered spaces 51 on the mold 5.

[0021] Step S3: Initiate curing. Specifically, after the curable ink between the protective cover plate 3 and the mold 5 is pressurized and spread into place, the curing process of the curable ink is initiated, allowing the curable ink to cure rapidly. In practice, the type of curable ink is not limited, as long as it is suitable for the waveguide support array requirements. For example, the curable ink can be a UV-curable ink, and step S3 specifically includes: curing the UV-curable ink with UV light (such as an LED UV lamp); or, the curable ink can be a thermosetting ink, and step S3 specifically includes: curing the thermosetting ink by heating.

[0022] Step S4: Demolding and Molding. Specifically, after the curing process of the curable ink is completed, the protective cover plate 3 is demolded from the mold 5, leaving the first side of the demolded protective cover plate 3 with an integrated first hardening layer 2 and multiple protrusions 1, which can form a support matrix. It can be understood that the shape of the first hardening layer 2 matches the layered space 51 of the injection space of the mold 5, and the shape of the protrusions 1 matches the concave space 52 of the injection space of the mold 5.

[0023] After adopting the waveguide lattice support structure fabrication method of the above embodiment, the hardening layer (i.e., the first hardening layer 2) and the support lattice can be simultaneously fabricated in a one-time and integrated transfer hardening process on one side of the protective cover plate 3. The support lattice and the hardening layer cooperate, support each other, and work together as a whole. In a test example, for the waveguide support lattice structure fabricated by conventional printing (such as screen printing) in related technologies, the support lattice began to break and disperse after a 6.5N / 1000 cycles compression molding test. However, for the waveguide support lattice structure fabricated in the above embodiment, the support lattice did not break and its appearance did not change significantly after a 6.5N / 12600 cycles compression molding test. It can be seen that compared with related technologies, this can effectively improve the mechanical strength of the support lattice, enhance its compressive strength and reliability, and thus avoid the Newton's rings effect defect caused by the support lattice failing too quickly due to the supporting effect. Meanwhile, since a single fabrication can produce an integrated hardening layer and support lattice, the fabrication efficiency of the waveguide support lattice structure is also improved.

[0024] In specific implementation, the waveguide lattice support structure fabrication method of the above embodiments can be further optimized or specified in at least one of the following ways: First, the first side of the protective cover plate 3 is preferably in an unprocessed (e.g., unhardened) green state, that is, an integrated hardening layer and support matrix are prepared on the green state side of the protective cover plate 3. Since the surface activity is higher in the green state, its chemical bonding or physical adhesion with curable ink is better, and the mechanical properties of the integrated hardening layer and support matrix prepared therefrom will also be better.

[0025] 2. In order to meet different support requirements, multiple concave spaces can be set with uniform intervals or random intervals. Correspondingly, multiple convex points are set with uniform intervals or random intervals.

[0026] 3. Mold 5 can be made of metal, glass, or resin. Preferably, in order to meet the preparation and processing requirements, mold 5 can be made of metal, such as M333 steel mold, which can simultaneously meet the needs of mold rigidity, temperature, clamping, and rapid demolding during the preparation process.

[0027] IV. The protective cover 3 can be made of transparent materials such as resin, glass, sapphire or silicon carbide.

[0028] See Figure 2 As shown, the waveguide lattice support structure fabrication method of the above embodiment may further include the following single or multiple steps: S0, S5, S6, S5 and S6, S5 and S6 and S7.

[0029] Step S0: Mold processing. Specifically, the injection space of mold 5 can be pre-processed on mold 5 before filling the curable ink into the injection space. For example, taking the mold as a metal material, the surface of the mold body is polished, and then a layered space 51 of a predetermined depth and a recessed space 52 of a predetermined diameter and depth are processed on the surface of the mold body. The arrangement or spacing of the recessed spaces is determined according to the requirements of the support matrix.

[0030] Step S5: Backside hardening. Specifically, a second hardening layer 4 can be provided on the other side of the protective cover plate 3, i.e., the second side. This step can be performed before step S1 or after step S4 (i.e., Figure 3 (As shown in the diagram). This results in a waveguide support lattice structure with hardened layers on both sides of the protective cover plate to meet the needs of subsequent practical use.

[0031] Step S6: Anti-reflection coating. Specifically, an anti-reflection coating can be deposited on the integrated first hardening layer 2 and multiple bumps 3, and an anti-reflection coating can be deposited on the second hardening layer 4 to improve the light transmittance of the waveguide dot matrix support structure and enhance the display effect of the waveguide.

[0032] Step S7: CNC machining. Specifically, after the antireflection film is deposited on the back hardening layer and the integrated hardening and support array, CNC (Computer Numerical Control) machining can be used to cut the waveguide array support structure into the required shape, which can then be used as a protective sheet for the diffractive waveguide.

[0033] In addition, the subsequent processes of the waveguide lattice support structure may further include steps S8 and S9.

[0034] Step S8: Waveguide bonding. Specifically, after fabricating the waveguide lattice support structure and cutting it into a protective sheet, the protective sheet with the support lattice can be bonded to the waveguide sheet with diffractive optical units to assemble them into a single unit. The side of the protective sheet with the support lattice faces the side of the waveguide sheet with the diffractive optical units, and the support lattice acts between them, controlling the minimum gap between them. The diffractive optical units mentioned above can be SRG (Surface Relief Grating) or VHG (Volume Holographic Grating) or other diffractive optical units.

[0035] Step S9: Glasses Assembly. Specifically, after the diffractive waveguide is bonded, it is further assembled with other components of the AR glasses to form the AR glasses. As mentioned earlier, due to the improved mechanical strength, compressive strength, and reliability of the support matrix, the supporting effect of the support matrix is ​​less likely to fail when the waveguide is subjected to external force or repeatedly pressed by the user during actual use of the AR glasses, and the AR glasses are less prone to the Newton's rings effect.

[0036] This application also provides a waveguide support lattice structure, which includes a protective cover plate 3, an integrated first hardening layer 2 disposed on a first side of the protective cover plate 3, and a plurality of protrusions 1; the waveguide support lattice structure is prepared by the waveguide lattice support structure preparation method described in any of the foregoing embodiments or specific methods. In summary, since the aforementioned waveguide lattice support structure preparation methods have the above-mentioned technical effects, the waveguide support lattice structure of this application embodiment also has corresponding technical effects, which will not be elaborated further here.

[0037] This application also provides a diffractive optical waveguide, which includes a waveguide sheet and the waveguide support lattice structure described in any of the above embodiments or specific methods, wherein the first side of the protective cover plate 3 covers the diffractive optical unit side of the waveguide sheet. The diffractive optical unit can be an SRG surface relief grating, or a VHG volume holographic grating, or other diffractive optical units. Since the aforementioned waveguide support lattice structure has the above-mentioned technical effects, the diffractive optical waveguide of this application also has corresponding technical effects, which will not be elaborated further here.

[0038] It should be noted that in the description of this application and its various embodiments, terms such as "top," "side," "upper," "lower," "height," and "depth" indicate the orientation or positional relationship, which are general expressions based on the orientation or positional relationship shown in the drawings or under actual field conditions. These are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0039] In this application and its various embodiments, unless otherwise explicitly stated or affecting logical consistency, the terms "set," "install," "connect," "link," "fix," etc., should be interpreted broadly. For example, where there is no conflict, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0040] In this application and its various embodiments, unless otherwise expressly specified and limited, the phrase "above" or "below" a second feature may include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of a second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" a second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0041] The specific embodiments described above have provided a detailed explanation of the purpose, technical solutions, and beneficial effects of this application. It should be understood that the above descriptions are merely specific embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for fabricating a waveguide lattice support structure, characterized in that, Including the following steps: Curable ink is filled into the injection space of the mold, the injection space including an outer layered space and an inner space with multiple recessed points spaced apart from each other; Align the first side of the protective cover with the injection space, so that the protective cover and the mold are attached and pressed together; Initiate the curing process of the curable ink; After the curing process is completed, the protective cover is demolded from the mold, so that an integrated first hardened layer and multiple protrusions are formed on the first side of the protective cover.

2. The method for fabricating a waveguide lattice support structure as described in claim 1, characterized in that, The first side of the protective cover is in an unprocessed raw board state.

3. The method for fabricating a waveguide lattice support structure as described in claim 1, characterized in that, The specific steps of attaching and pressing the protective cover plate and the mold together include: placing the first side of the protective cover plate on the mold with the liquid injection space facing upward; and rolling the second side of the protective cover plate with rollers.

4. The method for fabricating a waveguide lattice support structure as described in claim 1, characterized in that, The multiple concave points are spaced evenly or randomly.

5. The method for fabricating a waveguide lattice support structure as described in claim 1, characterized in that, The curable ink is a UV-curable ink, and the process of initiating the curing of the curable ink includes: curing the curable ink with UV light; or, the curable ink is a thermosetting ink, and the process of initiating the curing of the curable ink includes: curing the curable ink with heat.

6. The method for fabricating a waveguide lattice support structure as described in claim 1, characterized in that, The method further includes: providing a second hardening layer on the second side of the protective cover.

7. The method for fabricating a waveguide lattice support structure as described in claim 1, characterized in that, The method further includes: depositing an antireflective coating on the integrated first hardening layer and multiple bumps.

8. The method for fabricating a waveguide lattice support structure as described in any one of claims 1 to 7, characterized in that, Before filling the injection space of the mold with curable ink, the method further includes: pre-processing the injection space on the mold.

9. A waveguide-supported lattice structure, characterized in that, It includes a protective cover plate and an integrated first hardening layer and multiple protrusions disposed on the first side of the protective cover plate; the waveguide support lattice structure is prepared by the waveguide lattice support structure preparation method according to any one of claims 1 to 8.

10. A diffractive optical waveguide, characterized in that, The device includes a waveguide sheet and the waveguide support lattice structure as described in claim 9, wherein the first side of the protective cover plate is disposed on the diffraction optical unit side of the waveguide sheet.

Images