Single Waveguide Near Eye Display Using Time-Multiplexed Color
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Solution Overview
Problem
The complexity and cost of using multiple waveguides, each optimized for different colors, to address wavelength sensitivity issues in near eye displays, lead to expensive and complicated apparatuses.
Innovation Solution
A single waveguide with an entry and exit diffractive element is used, where the display device outputs images in a rapid sequence of colors, leveraging persistence of vision to merge colors simultaneously, reducing the need for multiple waveguides and simplifying the design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple waveguides are used, each optimized for different colors, then color accuracy is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent applies periodic action by sequentially displaying different color images (red, green, blue) in rapid succession through a single waveguide. The display device outputs images in a repeating sequence of different colors at a frequency of at least 50 Hz, utilizing the human visual system's persistence of vision to merge the sequential color images into a single full-color image. This temporal multiplexing approach eliminates the need for multiple parallel waveguides while maintaining color accuracy.
Solution Approach 2:
The patent changes the temporal parameter of light transmission by switching the wavelength of light passed through the single waveguide in sequence. Instead of transmitting multiple wavelengths simultaneously through multiple waveguides, the system transmits different wavelengths (colors) at different time intervals within each frame cycle, effectively using time-division multiplexing to achieve full-color display with a single waveguide structure.
2Manufacturing precision
If multiple waveguides are used, each optimized for different colors, then color accuracy is improved, but manufacturing cost increases
Solution Approach 1:
The patent merges the functions of multiple color-optimized waveguides into a single waveguide structure. By combining red, green, and blue image transmission capabilities into one waveguide and using sequential display with a single display device, the system reduces the number of components required. This merging approach significantly lowers manufacturing costs while maintaining the ability to display full-color images through temporal multiplexing.
3Adaptability or versatility
If multiple waveguides are used, each optimized for different colors, then color representation is improved, but the apparatus becomes expensive and complicated
Solution Approach 1:
The patent makes a single waveguide multi-functional by enabling it to transmit multiple colors sequentially. The same waveguide structure is used for red, green, and blue image transmission at different time intervals within each frame cycle. This universal waveguide design eliminates the need for separate dedicated waveguides for each color, reducing apparatus complexity while maintaining full-color representation capability through time-division multiplexing.
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 approach reduces the cost and complexity of near eye displays, enabling wider accessibility while maintaining effective color representation and detail resolution by sending images sequentially rather than simultaneously, thus avoiding image degradation.
Implementation Method 1
This display uses a diffraction grating to couple light from a display into the waveguide, and another diffraction grating to couple light—following total internal reflection in the waveguide—into the wearer's eye.
Implementation Method 2
another diffraction grating to couple light—following total internal reflection in the waveguide—into the wearer's eye
Implementation Method 3
If this switching is sufficiently rapid, a person viewing such a display will, on account of their persistence of vision, see all the colours simultaneously.
Data Source
AI summary
A near eye display comprising: a display device; and a waveguide; wherein the waveguide comprises an entry diffractive element and an exit diffractive element; wherein the display device is arranged to direct light into the waveguide via the entry diffractive element and wherein the exit diffractive element is arranged to direct light from the waveguide towards a user's eye; wherein the display device is arranged to output images in a repeating sequence of two or more different colours. Providing the images are transmitted in sufficiently quick succession, the brain will not perceive them as separate images, but will instead essentially merge them (as if they were overlaid on top of one another. As the brain is good at pattern recognition, it can compensate for any minor misalignments that occur between the different images. In this way the time-multiplexing approach avoids the need for multiple parallel waveguides for each specific colour or colour band.