Broadband optical system based on quantum dot wavelength conversion

Abstract

The invention discloses a broadband optical system based on quantum dot wavelength conversion, and relates to the technical field of micro display. The device comprises a blue light Micro-LED light source, a blazed grating, an RGB color quantum dot conversion module and an RGB beam combination module which are sequentially arranged along a light path, field sequential driving is adopted, and color patterns are formed through sequential controllable light beam deflection, quantum dot conversion and space beam combination. The system is simple and compact in structure, small in size and light in weight, light crosstalk and resolution loss can be effectively avoided, the color purity of a full-color image is remarkably improved, and the system cost is greatly reduced.

Description

Technical Field

[0001] This invention relates to the field of microdisplay technology, and more particularly to a broadband optical system based on quantum dot wavelength conversion. Background Technology

[0002] In near-eye display systems such as augmented reality (AR), virtual reality (VR), and smart glasses, full-color microdisplay optical engines are the core components for achieving highly immersive visual output. To meet the needs of human eye perception and the requirements of wearable devices for lightweight, low power consumption, and high reliability, the industry has developed various full-color technology pathways.

[0003] Currently, directly using full-color Micro-OLED microdisplay chips as the image source is one of the mainstream optical engine solutions. This technology relies on mature semiconductor CMOS backplane technology and OLED evaporation or inkjet printing processes, offering advantages such as high resolution, high contrast, fast response, and natural RGB pixelation. However, limited by the physical and chemical stability of organic electroluminescence, Micro-OLEDs are prone to material degradation under continuous high-brightness driving, leading to accelerated brightness decay and shortened lifespan. Furthermore, their typical peak brightness is generally below 2000 cd / m², making it difficult to meet outdoor visibility requirements in strong sunlight. Another mainstream solution is a beam-splitting and beam-combining optical engine based on independent red, green, and blue Micro-LED microdisplays. This involves driving three monochrome Micro-LED panels separately and achieving beam combining in both spatial and spectral dimensions through a polarization combining cube or dichroic film. This solution can achieve higher brightness, a wider color gamut, and faster response speed; however, it suffers from optical path redundancy, excessively large optical engine mass and size, and high cost. Therefore, to meet the urgent needs of consumer-grade AR glasses for miniaturization, long lifespan, high brightness, low power consumption, and scalable manufacturing, there is a pressing need for a novel full-color optomechanical technology that combines high photoelectric conversion efficiency, strong process compatibility, excellent stability, and a highly compact optical structure.

[0004] Against this backdrop, the full-color optomechanical solution based on blue Micro-LED chips exciting quantum dots for color conversion has become an important technological path in the field of full-color displays due to its breakthrough performance and manufacturing feasibility. This solution requires only a high-brightness, small-sized blue Micro-LED as a unified excitation source, and can generate RGB three-color emission at the pixel scale through pixel-level red and green quantum dot color conversion layers. This technology not only inherits the inherent advantages of Micro-LEDs such as high brightness, fast response, and long lifespan, but also avoids the technical bottleneck of mass transfer of RGB three-color Micro-LEDs, significantly simplifying the driving architecture and reducing system integration complexity. However, current full-color Micro-LEDs based on quantum dot color conversion still face problems such as complex fabrication processes, resolution reduction due to limited pixelation precision, and driving control difficulties caused by differences between blue LED pixels. Summary of the Invention

[0005] In view of the above-mentioned deficiencies of the prior art, the technical problem to be solved by the present invention is how to effectively avoid optical crosstalk and resolution loss of the full-color micro display optical engine, reduce the overall size and weight, and significantly improve the color purity of the full-color image.

[0006] To achieve the above objectives, the present invention provides a broadband optical system based on quantum dot wavelength conversion, comprising a blue Micro-LED light source, a blazed grating, an RGB color quantum dot conversion module, and an RGB beam combining module arranged sequentially along the optical path. It adopts field-sequence driving and forms a color pattern through beam deflection, quantum dot conversion, and spatial beam combining.

[0007] Furthermore, the blue Micro-LED light source includes a blue Micro-LED array, and the effective light-emitting area of ​​the blue Micro-LED light source is less than 90% of the tunable area of ​​the blazed grating.

[0008] Furthermore, the blazed grating is an electro-controlled liquid crystal blazed grating, the blazed grating has a groove structure, and the blazed grating includes a glass substrate, a nematic liquid crystal and a substrate arranged sequentially from top to bottom. The substrate is provided with distributed electrodes, and the diffraction angle of the blazed grating is greater than 15°.

[0009] Furthermore, the RGB color quantum dot conversion module includes spatially isolated green, blue, and red quantum dot conversion modules arranged sequentially along the optical path. The blue quantum dot conversion module is transparent, and the sizes of the green, blue, and red images are each smaller than the effective working area of ​​their respective quantum dot conversion modules. Each color quantum dot conversion module is precisely matched to the diffraction order of the blazed grating.

[0010] Furthermore, the RGB beam combining module includes a high-reflectivity mirror, a cholesteric liquid crystal polymer film for blue light reflection, and a cholesteric liquid crystal polymer film for red light reflection, arranged sequentially along the optical path.

[0011] Furthermore, the field sequence is set in the order of green, blue, and red, and the beam deflection is time-controlled.

[0012] This invention relates to a full-color micro-display optical engine for near-eye display systems, including augmented reality, virtual reality, and smart glasses.

[0013] Compared with the prior art, the present invention has the following advantages: (1) This invention requires only a blue Micro-LED chip, a blazed grating, a three-color quantum dot conversion module and a beam combining optical path. By timing the blue light and exciting the RGB quantum dots respectively, field-sequence full-color display can be achieved, significantly reducing the overall size and weight. The system structure is simple and compact, small in size and light in weight, greatly reducing the system cost, and also has good broadband spectral performance.

[0014] (2) The present invention uses blue Micro-LED and blazed grating to work together. The red, green and blue quantum dot color conversion modules are spatially isolated from each other and precisely matched with the diffraction order of the blazed grating to generate independent red, green and blue three-color patterns. This can effectively avoid optical crosstalk, fully preserve the inherent high resolution of Micro-LED, and significantly improve the color purity of full-color images.

[0015] The following will further explain the concept, specific structure, and technical effects of the present invention in conjunction with the accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the broadband optical system structure based on quantum dot wavelength conversion according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the optical structure of the electro-controlled liquid crystal blazed grating according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the optical structure of the RGB color conversion module in an embodiment of the present invention; Figure 4 This is a schematic diagram of the optical structure of the RGB beam combining module in an embodiment of the present invention.

[0017] Among them, 101-blue Micro-LED light source, 102-blazed grating, 103-RGB color quantum dot conversion module, 104-RGB beam combining module, 201-glass substrate, 202-substrate, 203-nematic liquid crystal, 301-green quantum dot conversion module, 302-transparent module, 303-red quantum dot conversion module, 401-high reflectivity mirror, 402-blue light reflection band cholesteric liquid crystal polymer film, 403-red light reflection band cholesteric liquid crystal polymer film. Detailed Implementation

[0018] The preferred embodiments of the present invention are described below with reference to the accompanying drawings to make the technical content clearer and easier to understand. The present invention can be embodied in many different forms, and the scope of protection of the present invention is not limited to the embodiments mentioned herein.

[0019] In the accompanying drawings, components with the same structure are indicated by the same numerical designation, and components with similar structures or functions are indicated by similar numerical designations. The dimensions and thicknesses of each component shown in the drawings are arbitrary, and the present invention does not limit the dimensions and thicknesses of each component. To make the illustrations clearer, the thickness of some components has been appropriately exaggerated in the drawings.

[0020] Currently, full-color micro-display optical engines face the following challenges: Existing quantum dot-based full-color Micro-LED solutions typically employ pixel-level patterning, directly integrating red, green, and two-color quantum dot color conversion layers onto a blue Micro-LED array to achieve independent emission of each sub-pixel, thus completing the full-color display. However, this structure faces challenges such as severe optical crosstalk, high complexity in precise quantum dot patterning processes, and resolution loss due to the aperture ratio occupied by isolation structures. This leads to low mass production yields and high manufacturing costs, ultimately limiting its practical application and industrialization in near-eye display scenarios such as AR / VR. Furthermore, existing full-color optical engines have large and heavy optical path systems. Whether it's a Micro-OLED microdisplay chip or a red-green-blue three-color composite Micro-LED microdisplay, the limitations in the number of screens and resolution result in significant size and weight, failing to meet the miniaturization and lightweight requirements of wearable devices such as AR.

[0021] To address the aforementioned issues, this invention proposes a broadband optical system based on a quantum dot wavelength conversion layer, combined with a blue Micro-LED excitation source and a blazed grating spectral modulation structure. While retaining the inherent advantages of a monolithic blue Micro-LED excitation structure, such as high brightness, wide color gamut, and nanosecond-level response speed, this optical system utilizes a blazed grating to selectively deflect blue light. Combined with a field-sequence driving method, it precisely guides the red and green light generated by the red and green quantum dot color conversion layers, along with the unconverted blue light, to the same position and superimposes them in chronological order, thereby achieving high-fidelity full-color image output and effectively improving the overall performance of the full-color micro-optical engine.

[0022] The broadband optical system based on quantum dot wavelength conversion proposed in this invention includes a blue Micro-LED light source, a blazed grating, an RGB color quantum dot conversion module, and an RGB beam combining module arranged sequentially along the optical path. It adopts green-blue-red field sequence driving and forms a color pattern through time-controlled beam deflection, quantum dot conversion, and spatial beam combining.

[0023] Among them, the blue Micro-LED light source includes a blue Micro-LED array, and the effective light-emitting area of ​​the blue Micro-LED light source is less than 90% of the adjustable area of ​​the blazed grating.

[0024] The blazed grating is an electro-controlled liquid crystal blazed grating. The blazed grating has a groove structure and includes a glass substrate, a nematic liquid crystal and a substrate arranged sequentially from top to bottom. The substrate is provided with distributed electrodes. The diffraction angle of the blazed grating is greater than 15°.

[0025] The RGB color quantum dot conversion module includes spatially isolated green, blue, and red quantum dot conversion modules arranged sequentially along the optical path. The blue quantum dot conversion module is transparent, and the sizes of the green, blue, and red images are each smaller than the effective working area of ​​their respective quantum dot conversion modules. Each color quantum dot conversion module is precisely matched to the diffraction order of the blazed grating.

[0026] The RGB beam combining module includes a high-reflectivity mirror, a cholesteric liquid crystal polymer film for blue light reflection, and a cholesteric liquid crystal polymer film for red light reflection, arranged sequentially along the optical path.

[0027] This invention relates to a full-color micro-display optical engine for near-eye display systems, including augmented reality, virtual reality, and smart glasses.

[0028] The implementation and realization of the technical solution of the present invention will be further described below through specific embodiments. It should be noted that the implementation and realization of the technical solution of the present invention are not limited to the following embodiments.

[0029] like Figure 1 As shown, the broadband optical system based on quantum dot wavelength conversion in this embodiment adopts a compact architecture, including a blue Micro-LED light source 101, a blazed grating 102, an RGB color conversion module 103, and an RGB beam combining module 104.

[0030] In this embodiment, the optical system uses a blue Micro-LED light source 101 as the unified light source for the entire system. The blue Micro-LED light source 101 includes a blue Micro-LED array, which is based on the photoluminescence characteristics of quantum dot materials. Short-wavelength blue light has sufficiently high photon energy, which can efficiently excite red and green quantum dots and emit high-purity red and green light respectively. Combined with direct blue light, it can achieve wide color gamut and high color purity RGB three primary color output. This optical system employs a field-sequential full-color display scheme. Within one frame period, the blue Micro-LED array sequentially emits three sets of intensity-modulated blue light patterns, corresponding to red, green, and blue subframes respectively. After being deflected by a blazed grating 102, the blue light patterns are sequentially incident on spatially isolated red, green, and blue quantum dot conversion modules. Specifically, during the red subframe period, the blue light is deflected to the red quantum dot layer for down-conversion emission; during the green subframe period, the blue light is deflected to the green quantum dot layer for down-conversion emission; and during the blue subframe period, the blue light is output as a corresponding monochrome image in zero-order or direct-through mode. The three time-separated RGB optical patterns are precisely spatially superimposed onto the same outgoing light path by an RGB beam combining module 104, and finally fused into a continuous, high-resolution full-color image by the persistence of vision. To ensure image integrity and color accuracy, the effective light-emitting area of ​​the Micro-LED is less than 90% of the adjustable area of ​​the blazed grating 102, and the diffraction angle of the blazed grating 102 is greater than 15°. This ensures that different diffraction orders (corresponding to R / G / B) are fully separated in space and do not overlap. At the same time, the size of each monochromatic image must be strictly smaller than the effective working area of ​​the corresponding quantum dot conversion module, thereby ensuring that all image details can be completely and accurately converted to color.

[0031] In this embodiment, the blazed grating 102 is an electro-controlled liquid crystal blazed grating. It dynamically adjusts the orientation of liquid crystal molecules through an applied voltage, reconstructing the phase distribution of the equivalent blazed grooves in real time. This allows for the selective diffraction of blue light corresponding to the red, green, and blue subframes onto spatially separated optical paths at different times, offering significant advantages such as millisecond-level response speed, no mechanical moving parts, and programmable deflection angle adjustment. Figure 2 As shown, the blazed grating 102 in this embodiment includes a glass substrate 201, a base 202, and a nematic liquid crystal 203. The base 202 is provided with distributed electrodes, and the phase distribution of the liquid crystal conforms to the groove structure of the blazed grating by modulation of the electric field.

[0032] like Figure 3As shown, the RGB color quantum dot conversion module 103 in this embodiment includes a green quantum dot conversion module 301, a transparent module 302 (i.e., a blue quantum dot conversion module), and a red quantum dot conversion module 303, which are spatially isolated and arranged sequentially along the optical path. The green quantum dot conversion module 301 is responsible for converting the blue pattern deflected by the blazed grating into a green pattern, the transparent module 302 directly transmits the polarized blue pattern, and the red quantum dot module 303 is responsible for converting the blue pattern deflected by the blazed grating into a red pattern.

[0033] like Figure 4 As shown, the RGB beam combining module 104 in this embodiment includes a high-reflectivity mirror 401 (hereinafter referred to as the mirror), a cholesteric liquid crystal polymer film 402 (hereinafter referred to as the blue light film), and a cholesteric liquid crystal polymer film 403 (hereinafter referred to as the red light film), arranged sequentially along the optical path. The three components work together to achieve spatial beam combining and path normalization of red, green, and blue light. The green light pattern is incident on the mirror 401, and after efficient reflection, it is redirected to the main outgoing light path. Furthermore, because the green light wavelength is neither... The blue light pattern is not within the reflection band of the blue light film 402, nor within the reflection band of the red light film 403. Therefore, it maintains high transmittance when passing through these two films and successfully merges into the outgoing optical axis. The blue light pattern first enters the blue light film 402 and is selectively reflected and deflected because it is in the Bragg reflection band of the film. Since it is not within the reflection band of the red light film 403, it successfully merges into the outgoing optical axis after passing through the red light film. The red light pattern enters the red light film 403 and undergoes selective reflection within its reflection band, directly deflecting and merging into the outgoing optical axis. Thus, although the initial incident positions and paths of the three colors of light are different, through the selective transmission or reflection of specific wavelengths by each film layer and the directional guidance of the mirror, they are all ultimately precisely converged into the same outgoing optical axis, achieving low crosstalk and high-efficiency full-color spatial beam combining.

[0034] In this embodiment, the entire architecture achieves a compact, highly efficient, and extremely low crosstalk Micro-LED full-color micro-display solution under single-source driving conditions through the combined synergistic effect of beam deflection by the blazed grating and wavelength-selective reflection by the cholesteric liquid crystal polymer film.

[0035] This invention introduces a blazed grating to controllably deflect the blue Micro-LED emitted beam, enabling red, green, and blue light to be sequentially excited and output along the same optical path, thus constructing a full-color display mechanism based on the field sequence principle. Because the three colors are strictly separated in time and have no physical pixel overlap in space, the optical color mixing problem caused by blue light diffraction and lateral light leakage in traditional RGB sub-pixel juxtaposition structures is fundamentally avoided, significantly improving color purity, color gamut coverage, and contrast. Simultaneously, the quantum dot color conversion layer no longer relies on high-precision patterning processes but adopts a large-area segmented thin-film structure. The color conversion regions are physically isolated but optically shared, greatly relaxing manufacturing tolerances. This not only improves process yield and reduces material and equipment costs but also enhances the compatibility and mass production feasibility of large-size substrates. By using quantum dot excitation, the full-color optical path system requires only one Micro-LED screen, a blazed grating, a corresponding beam combining optical path, and a color conversion module. This greatly reduces the size and weight of the device and simplifies the previously expensive three-color laser light source to a single-color blue light source, significantly reducing system costs and providing a feasible technical path for commercial applications in consumer-grade AR glasses.

[0036] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A broadband optical system based on quantum dot wavelength conversion, characterized in that, It includes a blue Micro-LED light source, a blazed grating, an RGB color quantum dot conversion module, and an RGB beam combining module arranged sequentially along the optical path. It adopts field sequence driving and forms a color pattern through beam deflection, quantum dot conversion, and spatial beam combining.

2. The broadband optical system based on quantum dot wavelength conversion as described in claim 1, characterized in that, The blue Micro-LED light source includes a blue Micro-LED array, and the effective light-emitting area of ​​the blue Micro-LED light source is less than 90% of the adjustable area of ​​the blazed grating.

3. The broadband optical system based on quantum dot wavelength conversion as described in claim 1, characterized in that, The blazed grating is an electro-controlled liquid crystal blazed grating, the blazed grating has a groove structure, and the blazed grating includes a glass substrate, a nematic liquid crystal and a substrate arranged sequentially from top to bottom, and the substrate is provided with distributed electrodes.

4. The broadband optical system based on quantum dot wavelength conversion as described in claim 3, characterized in that, The diffraction angle of the blazed grating is greater than 15°.

5. The broadband optical system based on quantum dot wavelength conversion as described in claim 1, characterized in that, The RGB color quantum dot conversion module includes a green quantum dot conversion module, a blue quantum dot conversion module, and a red quantum dot conversion module that are spatially isolated from each other and arranged sequentially along the optical path.

6. The broadband optical system based on quantum dot wavelength conversion as described in claim 5, characterized in that, The blue quantum dot conversion module is a transparent module, and the sizes of the green, blue, and red images are smaller than the effective working area of ​​the corresponding quantum dot conversion module.

7. The broadband optical system based on quantum dot wavelength conversion as described in claim 5, characterized in that, The color quantum dot conversion modules are precisely matched with the diffraction orders of the blazed grating.

8. The broadband optical system based on quantum dot wavelength conversion as described in claim 1, characterized in that, The RGB beam combining module includes a high-reflectivity mirror, a cholesteric liquid crystal polymer film for blue light reflection, and a cholesteric liquid crystal polymer film for red light reflection, arranged sequentially along the optical path.

9. The broadband optical system based on quantum dot wavelength conversion as described in claim 1, characterized in that, The field sequence is set in the order of green, blue, and red, and the beam deflection is time-controllable.

10. The broadband optical system based on quantum dot wavelength conversion as described in any one of claims 1-9, characterized in that, A full-color micro-display optical engine for use in near-eye display systems, including augmented reality, virtual reality, and smart glasses.

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