Diffractive Lightguide Image Projection for Full RGB Color Gamut
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Solution Overview
Problem
Existing light guide displays are often optimized for narrow wavelength bands, requiring multiple light guides to achieve a larger color gamut, which is expensive and adds weight and volume, making it challenging to achieve efficient and cost-effective full RGB color rendering.
Innovation Solution
The apparatus employs a combination of first and second display means projecting light in different wavelength bands, with the first display means projecting light to form images at both eyes and the second display means using a diffractive lightguide to project light in a second band, allowing for the superposition of images in register to create a full RGB image, reducing the need for multiple light guides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If multiple light guides are used to provide a larger color gamut, then the color gamut is improved, but the cost, weight, and volume increase
Solution Approach 1:
The patent segments the wavelength spectrum into different bands (e.g., blue band around 450nm and red band around 630nm) and uses separate light guides optimized for each band. This allows each light guide to be specialized for a narrow wavelength range, achieving high color purity and gamut while avoiding the need for a single complex light guide to handle the entire spectrum
Solution Approach 2:
The patent combines multiple light guides (each handling a narrow wavelength band) into a unified display system where their outputs are superimposed. By merging the outputs of specialized light guides, the system achieves a broad color gamut equivalent to or exceeding that of a single wide-band light guide, while maintaining the advantages of wavelength-specific optimization
2Stability of the object's composition
If multiple light guides are used to achieve a larger color gamut, then the color rendering is improved, but the weight and volume increase
Solution Approach 1:
Instead of using one heavy, bulky light guide that attempts to cover the entire visible spectrum, the patent divides the task into multiple specialized light guides, each handling a narrow wavelength band. This segmentation allows for more efficient material selection and thinner designs for each component, reducing the overall weight while achieving superior color gamut through the combination of specialized guides
3Stability of the object's composition
If multiple light guides are used to provide a larger color gamut, then the color rendering is improved, but the volume increases
Solution Approach 1:
The patent employs a nested arrangement where multiple light guides are stacked or layered in a compact configuration. Each light guide is optimized for a specific wavelength band and is positioned to work in conjunction with the others, creating a space-efficient structure that achieves broad color gamut without requiring a large overall volume
Solution Approach 2:
The patent transitions from a planar arrangement to a three-dimensional stacked configuration of light guides. By utilizing the vertical dimension and stacking light guides in layers, the system achieves a compact form factor that accommodates multiple wavelength-specific guides while maintaining a small overall volume
4Device complexity
If a single light guide is used, then the device complexity is reduced, but the color gamut is limited to a narrow band
Solution Approach 1:
The patent segments the color spectrum into multiple narrow wavelength bands, each handled by a dedicated light guide. This segmentation allows each light guide to be optimized for its specific wavelength range, achieving high efficiency and color purity that would be impossible for a single light guide to achieve across the entire spectrum
Solution Approach 2:
The patent creates a multi-functional display system where each light guide performs a specialized function (handling a specific wavelength band) but collectively they fulfill the universal function of providing a broad color gamut. This division of labor allows each component to be highly optimized for its specific task while the system as a whole achieves comprehensive color coverage
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables the creation of a full RGB color gamut with reduced complexity and cost, maintaining efficiency and uniformity across a wide wavelength band, while minimizing the number of light guides required.
Implementation Method 1
a diffractive lightguide configured to project light in a second band of wavelengths emitted by the second display to form a third image
Data Source
Figure 1~3
Figure 4A~4B
Figure 5~6
AI summary
An apparatus comprising: a first display means projecting light in a first band of wavelengths to form a first image at a first eye of a user and for projecting light in the first band of wavelengths to form a second image at a second eye of the user; a second display means for projecting light in a second band of wavelengths to form a third image at the first eye of the user and at the second eye of the user, wherein the first band of wavelengths and the second band of wavelengths are different.