Diffraction optical waveguide, display device and vehicle

Abstract

The utility model relates to a diffractive optical waveguide, a display device and a vehicle, the diffractive optical waveguide comprises a glass substrate, a binder layer, a film substrate and a nanoimprint glue layer which are sequentially arranged along the thickness direction, the surface of the nanoimprint glue layer is sequentially provided with a coupling-in grating, a plurality of turning gratings and a coupling-out grating along a light transmission path, the plurality of gratings in the coupled-in grating are set as blazed gratings with the same grating parameters, the plurality of turning gratings and the plurality of gratings in the coupled-out grating are respectively set as blazed gratings with at least one grating parameter gradually changing along a light transmission path, and the grating parameters comprise a grating period, a duty ratio, a blazed angle and an anti-blazed angle; a display device including an optical machine and a diffractive optical waveguide; a vehicle includes a frame with a windshield, an optical machine, and a diffractive optical waveguide. The diffraction optical waveguide has the advantages of being convenient to manufacture in batches and capable of improving the efficiency of the large-area embossment grating, further improving the display efficiency of the display device and the vehicle using the diffraction optical waveguide, and reducing the application cost of an AR-HUD scheme.

Description

Technical Field

[0001] This utility model relates to the technical field of optical elements, and in particular to a diffractive waveguide, a display device, and a vehicle. Background Technology

[0002] Head-up display (HUD) technology was initially used in fighter jet cockpits to assist pilots in flight operations. With the continuous advancement of HUD technology, it has gradually been adopted by passenger cars as well. HUD projects vehicle driving information and navigation information at a specific distance in front of the windshield, allowing drivers to focus on both road conditions and navigation information simultaneously without looking down at a traditional instrument panel, significantly improving driving safety. Therefore, HUD technology is receiving increasing attention and favor from automakers and users. In recent years, the development of HUD technology has been rapid, with more and more car models being equipped with it.

[0003] Currently, the main automotive HUD technology on the market uses windshield HUDs (W-HUDs), which primarily consist of an image generation unit (PGU), a freeform mirror, and a windshield. The image generated by the PGU is reflected by the freeform mirror and windshield to the driver's eyes, forming a virtual image at a distance. PGU display solutions mainly include TFT, Lcos, and DLP. The mirror can be a freeform mirror, an aspherical mirror, or a combination of both, and can be equipped with an electric control unit to adjust the image projection position. Due to limitations in field of view and exit pupil distance, the content displayed by W-HUDs is relatively simple, and the market is exploring augmented reality head-up display (AR-HUD) solutions.

[0004] AR-HUD solutions primarily apply waveguide technology from AR near-eye displays to HUDs, maintaining pupil expansion functionality while significantly reducing the size of the HUD optical system. This increases performance indicators such as the field of view, further improving the size and performance of HUD technology. In waveguide HUD solutions, the PGU projects and couples the light beam into the waveguide. After two-dimensional pupil expansion within the waveguide, the beam is projected onto the windshield and reflected by the windshield to the driver's eyes. Waveguide HUD solutions mainly employ two-dimensional pupil expansion technology. The PGU beam is coupled into the waveguide in the coupling region, propagates through total internal reflection within the waveguide, and undergoes horizontal and vertical pupil expansion in the turning and coupling regions, finally coupling out in the coupling region. Currently, there are three main types of waveguide HUD solutions: 1. Arrayed waveguide solutions using semi-transparent and semi-reflective films; 2. Embossed grating solutions using large-area straight gratings; 3. Holographic volume grating solutions using volume holographic gratings.

[0005] There are currently three main waveguide HUD solutions: arrayed waveguide, embossed grating waveguide, and volume holographic grating waveguide. Arrayed waveguide solutions offer high efficiency but have complex manufacturing processes, high mass production costs, and the semi-transparent / semi-reflective coating may affect the visual experience. Volume holographic grating waveguide solutions facilitate the fabrication of large-area volume holographic gratings but have lower efficiency and are affected by exposure and materials, resulting in significant background stray light. Embossed grating waveguide solutions have gained considerable market attention and favor in small-area waveguide solutions for near-eye displays due to the mass production advantages of semiconductor processing or nanoimprinting. However, their application in large-area waveguides is relatively limited. First, large-area relief gratings are difficult to fabricate. Despite the availability of semiconductor processing and nanoimprinting technologies, the current mass production yield of large-area relief gratings is low. They are commonly fabricated using dual-beam exposure and etching methods, followed by direct board-to-board imprinting on a large area. This method suffers from low yield and high cost due to the stability issues of dual-beam exposure and the direct board-to-board imprinting onto the glass substrate. The high cost is partly due to the high cost of large-area glass substrates. Second, the commonly used straight grating structure for large-area relief gratings is inefficient and cannot effectively improve the efficiency of large-area relief grating waveguides.

[0006] Based on the current market situation and the aforementioned analysis, the AR-HUD solution is currently the most promising solution for revolutionizing HUD technology. Within the AR-HUD solution, the large-area embossed grating waveguide approach demonstrates enormous potential due to its mass production capabilities. Utility Model Content

[0007] The first objective of this invention is to provide a diffractive waveguide that is easy to mass-produce and can improve the efficiency of large-area relief gratings.

[0008] The second objective of this invention is to provide a display device that has the advantages of reducing the application cost of AR-HUD solutions and improving display efficiency.

[0009] The third objective of this invention is to provide a vehicle that has the advantages of reducing the application cost of AR-HUD solutions and improving display efficiency.

[0010] To achieve the first objective mentioned above, this utility model provides the following technical solution:

[0011] A diffractive waveguide includes a glass substrate, an adhesive layer, a thin film substrate, and a nanoimprinted adhesive layer arranged sequentially along the thickness direction. The surface of the nanoimprinted adhesive layer is sequentially provided with an input grating, a plurality of transition gratings, and an output grating along the light transmission path. The plurality of gratings in the input grating are configured as blazed gratings with identical grating parameters. The plurality of transition gratings and the plurality of gratings in the output grating are each configured as at least one blazed grating with grating parameters that gradually change along the light transmission path. The grating parameters include grating period, duty cycle, blaze angle, and anti-blaze angle.

[0012] By adopting the above technical solution, firstly, this utility model, through the structural design of a thin film substrate combined with a nanoimprint adhesive layer, can combine the nanoimprint scheme in the applicant's recently filed Chinese patent with publication number CN118226649A to achieve large-area relief grating processing, thereby improving processing yield and significantly reducing processing costs. Secondly, compared with the traditional straight grating structure, the blazed grating structure is more adaptable to the above-mentioned batch processing method. Moreover, the blazed grating structure is a sawtooth structure, which can adjust the shape and duty cycle of the blazed grating structure. Taking a straight grating with a grating period of 334nm and a grating refractive index of 1.9 as an example, a comparison of +1 diffraction efficiency was conducted. Under the illumination of a beam with an incident angle of -15° to +15° and a wavelength of 532nm, it can be clearly seen that the blazed grating has higher efficiency and can more significantly improve the efficiency of large-area relief grating waveguides.

[0013] The present invention is further configured such that the glass substrate is K9 glass.

[0014] By adopting the above technical solutions, the optical performance of diffractive waveguide products can be effectively improved. K9 glass has excellent light transmittance and stability, ensuring the accuracy and clarity of the light beam during transmission, thereby enhancing the display effect of AR-HUD display devices. At the same time, K9 glass also has good processing performance, meeting the needs of different shapes and sizes, facilitating personalized product customization.

[0015] The present invention is further configured such that the thin film substrate is a PET film or a PC film.

[0016] By adopting the above technical solutions, the flexibility and durability of diffractive waveguides can be further enhanced. Both PET and PC films have good optical transparency, which can effectively reduce light loss during transmission and improve diffraction efficiency. At the same time, these two film materials also have excellent mechanical strength, which can effectively resist damage to diffractive waveguides from the external environment and extend the product's service life. In addition, PET and PC films also have good processing performance, which can meet the needs of various complex shapes and sizes, providing more possibilities for the personalized design of diffractive waveguides.

[0017] The present invention is further configured such that the adhesive layer is composed of a tackifier.

[0018] By adopting the above technical solutions, the bonding strength and stability of diffractive waveguides can be significantly improved.

[0019] The present invention is further configured such that the nanoimprinted photoresist layer is composed of nanoimprinted photoresist with a refractive index of 1.5 or higher.

[0020] By employing the above technical solution, nanoimprint photoresist with a refractive index of 1.5 or higher possesses excellent light transmittance and photocuring properties, enabling precise replication of mold patterns at the nanoscale, thereby fabricating high-precision diffraction grating structures. This high-precision diffraction grating structure can effectively control the direction of light propagation, improving the diffraction efficiency of light waves, allowing display devices to present clearer and brighter images. Simultaneously, the nanoimprint photoresist layer also exhibits good adhesion and abrasion resistance, ensuring stable performance of the diffraction waveguide during use and extending the product's lifespan.

[0021] The present invention is further configured such that: the grating period of the coupled grating is 380~400nm, the duty cycle is 100%, the blaze angle is 10~40°, and the anti-blaze angle is 60~90°.

[0022] By adopting the above technical solution, it is beneficial to improve the efficiency of large-area relief gratings.

[0023] The present invention is further configured such that: the grating period of the transition grating is 260~290nm, the duty cycle range is 40~100%, the blaze angle is 10~40°, and the anti-blaze angle is 90°, and the duty cycle or blaze angle of the multiple gratings of the transition grating increases along the light transmission path.

[0024] By adopting the above technical solution, it is beneficial to improve the efficiency of large-area relief gratings.

[0025] The present invention is further configured such that: the grating period of the coupled grating is 380~400nm, the duty cycle range is 40~100%, the blaze angle is 10~40°, and the anti-blaze angle is 60~90°, and the duty cycle or blaze angle of the multiple gratings of the coupled grating increases along the light transmission path.

[0026] By adopting the above technical solution, it is beneficial to improve the efficiency of large-area relief gratings.

[0027] To achieve the second objective mentioned above, this utility model provides the following technical solution:

[0028] A display device includes an optomechanism and the aforementioned diffractive waveguide, wherein the diffractive waveguide is arranged on the light output path of the optomechanism with its coupling direction facing the light output end of the optomechanism.

[0029] By adopting the above technical solution, after the light is emitted by the optomechanical system, it is coupled into the glass substrate through the coupling grating of the diffractive waveguide and propagates in the glass substrate. When the light propagates to the deflection grating, it will be deflected and the pupil will be expanded, changing the direction of propagation. Subsequently, the light continues to propagate to the coupling grating, is coupled out into the air, and then enters the human eye to realize the display of the image. It has the advantages of reducing the application cost of AR-HUD solutions and improving display efficiency.

[0030] To achieve the third objective mentioned above, this utility model provides the following technical solution:

[0031] A vehicle includes a frame with a windshield, an optical engine (PGU), and the aforementioned diffractive waveguide, wherein the diffractive waveguide is arranged on the light output path of the optical engine with its coupling direction facing the light output end of the optical engine, and the diffractive waveguide is mounted on the frame with its coupling direction facing the windshield.

[0032] By adopting the above technical solution, after the light is emitted by the optomechanical system, it first passes through the coupling grating of the diffractive waveguide and enters the interior of the glass substrate for transmission. The design of the diffractive waveguide enables the light to be transmitted effectively in the glass substrate and maintains high brightness and clarity during transmission. When the light is transmitted to the deflection grating, it will be deflected and the pupil will be expanded, that is, the transmission direction of the light will change to expand the coverage of the light on the windshield, thereby providing a wider field of view. Subsequently, the light continues to be transmitted to the output grating, and is coupled out from the glass substrate into the air, and finally enters the driver's eyes to realize the display of the image. The driver can see the image information projected by the display device, such as navigation instructions and vehicle status, through the windshield, improving driving safety and convenience.

[0033] In summary, the beneficial technical effects of this utility model are as follows:

[0034] 1. The diffractive waveguide of this invention, through the structural design of combining a thin film substrate with a nano-imprinted adhesive layer, and attaching it to the release substrate through an adhesive layer, can realize the processing of large-area relief gratings, thereby improving the processing yield and significantly reducing the processing cost. Furthermore, the coupling grating, the turning grating, and the coupling grating all adopt the blazed grating structure, which has the advantages of facilitating mass production and improving the efficiency of large-area relief gratings.

[0035] 2. The display device of this utility model has the advantages of reducing the application cost of AR-HUD solutions and improving display efficiency due to the low manufacturing cost and high display efficiency of the diffractive waveguide.

[0036] 3. The vehicle of this utility model has the advantages of reducing the application cost of AR-HUD solutions and improving display efficiency due to the low manufacturing cost and high display efficiency of the diffractive waveguide, thereby improving vehicle performance. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the diffractive waveguide structure of Embodiment 1 of this utility model.

[0038] Figure 2 This is a schematic diagram of the structure of the nanoimprint adhesive layer in Embodiment 1 of this utility model.

[0039] Figure 3 This is a comparison diagram of the diffraction efficiency of the straight grating and the blazed grating of Embodiment 1 of this utility model.

[0040] Figure 4 This is a schematic diagram of the structure of the coupling grating, the turning grating and the coupling grating of Embodiment 2 of this utility model.

[0041] Figure 5 This is a schematic diagram of the diffractive waveguide structure of Embodiment 3 of this utility model.

[0042] Figure 6 This is a schematic diagram of the display device according to Embodiment 5 of this utility model.

[0043] In the figure, 1 is the glass substrate; 2 is the adhesive layer; 3 is the thin film substrate; 4 is the nanoimprint adhesive layer; 41 is the coupling grating; 42 is the folding grating; 43 is the coupling grating; 5 is the optomechanical system; and 6 is the windshield. Detailed Implementation

[0044] To make the technical means, creative features, objectives and effects of this utility model clearer and easier to understand, the present utility model will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0045] Example 1: Refer to Figure 1 and Figure 2 This invention discloses a diffractive optical waveguide, comprising a glass substrate 1, an adhesive layer 2, a thin film substrate 3, and a nanoimprinted adhesive layer 4 arranged sequentially along the thickness direction. The surface of the nanoimprinted adhesive layer 4 is provided with a coupling grating 41, a transition grating 42, and a coupling grating 43 arranged sequentially along the light transmission path. Multiple gratings in the coupling grating 41 are configured as blazed gratings with identical grating parameters. Multiple gratings in the transition grating 42 and the coupling grating 43 are each configured as blazed gratings with at least one grating parameter that gradually changes along the light transmission path. The grating parameters include grating period, duty cycle, blaze angle, and anti-blaze angle.

[0046] In addition, the glass substrate 1 is K9 glass, the thin film substrate 3 is PET film or PC film, and in this embodiment, PET film is preferred. The adhesive layer 2 is composed of an adhesive agent, and the nanoimprint photoresist layer 4 is composed of nanoimprint photoresist with a refractive index of 1.5 or higher.

[0047] First, this utility model, through the structural design of a thin film substrate 3 combined with a nanoimprint adhesive layer 4, can achieve large-area relief grating processing by combining the nanoimprint scheme in the applicant's recently filed Chinese patent with publication number CN118226649A, thereby improving the processing yield and significantly reducing the processing cost. The specific implementation method is as follows:

[0048] S1 large-area relief grating master and nanoimprint working template production. The template master can be exposed by electron beam, photolithography and double beam interference, and large-area master can be produced by etching process. Alternatively, the master and working template can be made by panelization on this basis.

[0049] S2 nanoimprinting uses PET or PC film as film substrate 3, and pre-coats nanoimprinting photoresist with a refractive index of 1.5 or higher on the surface of film substrate 3. Nanoimprinting is performed in a roll-to-plate, roll-to-roll, or plate-to-plate manner with stepping and specific pressure parameters, thereby transferring the blazed grating structure on the master or working template onto film substrate 3. Heat treatment and ultraviolet curing treatment can be performed before and after nanoimprinting according to the characteristics of nanoimprinting photoresist.

[0050] S3 thin film transfer: The semi-finished product obtained in S2 is attached to the glass substrate 1 through the adhesive layer 2, and after cutting and packaging, it becomes the final diffractive waveguide product used in AR-HUD display devices. Since the cost of the thin film substrate 3 is low, and the above nanoimprinting method can significantly reduce the cost of large-area imprinting, the thickness of the thin film substrate 3 should be less than 1 mm, and the thickness of the glass substrate 1 is determined according to the HUD parameters. Under normal circumstances, the thickness is greater than 1 mm, and the material is K9 glass or other glass materials.

[0051] Reference Figure 3 Secondly, compared with the traditional straight grating structure, the blazed grating structure is more suitable for the above-mentioned batch processing method. Moreover, the blazed grating structure is a sawtooth structure, which can adjust the shape and duty cycle of the blazed grating structure. Taking a straight grating with a grating period of 334nm and a grating refractive index of 1.9 as an example, a comparison of +1 diffraction efficiency was carried out. Under the illumination of a beam with a wavelength of 532nm at an incident angle of -15° to +15°, it can be clearly seen that the blazed grating has higher efficiency and can significantly improve the efficiency of large-area relief grating waveguides.

[0052] Example 2: Refer to Figure 4 This is a diffractive waveguide disclosed in this utility model. The difference from Embodiment 1 is that the coupling region size of the coupling grating 41 is 15×10mm, the grating period is 390nm, the duty cycle is 100%, the blaze angle is 30°, and the anti-blaze angle is 60°.

[0053] The transition region of the transition grating 42 is 215×23mm, the grating period is 276nm, the duty cycle range is 50~100%, the blaze angle is 30°, the anti-blaze angle is 90°, and the duty cycle of the multiple gratings of the transition grating 42 increases along the light transmission path.

[0054] The coupling region of the coupling grating 43 has a size of 200×95mm, a grating period of 390nm, a duty cycle range of 50~100%, a blaze angle of 25°, and an anti-blaze angle of 70°. The duty cycles of the multiple gratings of the coupling grating 43 increase along the optical transmission path.

[0055] The diffractive waveguide utilizes the aforementioned large-area relief grating processing method, employing nanoimprint adhesive with a refractive index of 1.5 or higher to imprint onto a 0.2mm thick PET film. The imprinted PET film is then cut and attached to a 2mm thick K9 glass substrate 1, resulting in the final grating waveguide product used in AR-HUD display devices. Alternatively, grating modulation can be achieved by adjusting the blaze angle or using a blaze structure with a gradual change in shape.

[0056] Example 3: Reference Figure 5 This invention discloses a diffractive waveguide, which differs from Embodiment 2 in that two folding gratings 42 are provided and symmetrically arranged on both sides of the coupling grating 41.

[0057] Example 4: Reference Figure 6 This is a display device disclosed in this utility model. The difference from embodiment 2 is that it includes an optomechanism 5 and the above-mentioned diffractive waveguide. The diffractive waveguide is arranged on the light output path of the optomechanism 5 in such a way that the coupling direction is toward the light output end of the optomechanism 5.

[0058] After being emitted by the optomechanical system 5, the light is coupled into the glass substrate through the coupling grating 41 of the diffractive waveguide and propagates in the glass substrate. When the light reaches the deflection grating 42, it will be deflected and the pupil will be expanded, changing the direction of propagation. Subsequently, the light continues to propagate to the coupling grating 43, is coupled out into the air, and then enters the human eye to realize the display of the image. It has the advantages of reducing the application cost of AR-HUD solutions and improving display efficiency.

[0059] Example 5: Refer to Figure 6 This is a vehicle disclosed in this utility model. The difference from embodiment 4 is that it includes a frame with a windshield 6 (not shown in the figure), an optomechanical unit (PGU) 5, and the aforementioned diffractive waveguide. The diffractive waveguide is arranged on the light output path of the optomechanical unit 5 with the coupling direction facing the light output end of the optomechanical unit 5, and the diffractive waveguide is installed on the frame with the coupling direction facing the windshield 6.

[0060] After being emitted by the optical engine 5, the light first passes through the coupling grating 41 of the diffractive waveguide and enters the interior of the glass substrate for transmission. The design of the diffractive waveguide enables the light to be transmitted effectively in the glass substrate and maintains high brightness and clarity during transmission. When the light is transmitted to the deflection grating 42, it will be deflected and the pupil will be expanded, that is, the transmission direction of the light will change to expand the coverage of the light on the windshield 6, thereby providing a wider field of view. Subsequently, the light continues to be transmitted to the coupling grating 43, and is coupled out from the glass substrate into the air, and finally enters the driver's eyes, which can realize the AR-HUD content display of 10°×4° FOV. The driver can see the image information projected by the display device, such as navigation instructions and vehicle status, through the windshield 6, improving driving safety and convenience.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model and are not intended to limit it. Although this utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this utility model without departing from the spirit and scope of the technical solutions of this utility model, and all such modifications or substitutions should be covered within the scope of the claims of this utility model.

Claims

1. A diffractive optical waveguide, characterized by: The glass substrate (1), the adhesive layer (2), the film substrate (3) and the nanoimprint glue layer (4) are arranged in sequence along the thickness direction, the surface of the nanoimprint glue layer (4) is provided with the incoupling grating (41), the turning grating (42) and the outcoupling grating (43) along the light transmission path in sequence, the gratings in the incoupling grating (41) are arranged as blaze gratings with the same grating parameters, the gratings in the turning grating (42) and the outcoupling grating (43) are arranged as blaze gratings with at least one grating parameter gradually changing along the light transmission path, and the grating parameters include the grating period, the duty cycle, the blaze angle and the anti-blaze angle.

2. A diffractive optical waveguide according to claim 1, wherein: The glass substrate (1) is K9 glass.

3. A diffractive optical waveguide according to claim 1, wherein: The film substrate (3) is PET film or PC film.

4. A diffractive optical waveguide according to claim 1, wherein: The adhesive layer (2) is composed of a tackifier.

5. A diffractive optical waveguide according to claim 1, wherein: The nanoimprint glue layer (4) is composed of a nanoimprint photoresist with a refractive index of 1.5 or more.

6. A diffractive optical waveguide according to claim 1, wherein: The grating period of the incoupling grating (41) is 380-400 nm, the duty cycle is 100%, the blaze angle is 10-40°, and the anti-blaze angle is 60-90°.

7. A diffractive optical waveguide according to claim 1, wherein: The grating period of the turning grating (42) is 260-290 nm, the duty cycle ranges from 40% to 100%, the blaze angle is 10-40°, and the anti-blaze angle is 90°, and the duty cycle or the blaze angle of the gratings of the turning grating (42) increases along the light transmission path.

8. A diffractive optical waveguide according to claim 1, wherein: The grating period of the outcoupling grating (43) is 380-400 nm, the duty cycle ranges from 40% to 100%, the blaze angle is 10-40°, and the anti-blaze angle is 60-90°, and the duty cycle or the blaze angle of the gratings of the outcoupling grating (43) increases along the light transmission path.

9. A display device, characterized by: The diffractive optical waveguide according to any one of claims 1-8 is arranged on the light path of the light machine (5) in a manner that the incoupling direction is towards the light outlet end of the light machine (5).

10. A vehicle characterized by: The diffractive optical waveguide according to any one of claims 1-8 is arranged on the light path of the light machine (5) in a manner that the incoupling direction is towards the light outlet end of the light machine (5), and the diffractive optical waveguide is installed on the vehicle frame in a manner that the outcoupling direction is towards the windshield (6).

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