Switchable Grating Waveguide for Spectacle-Free 3D Viewing
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Solution Overview
Problem
Conventional three-dimensional displays require spectacles to block light for one eye, causing flicker and discomfort, as they cannot efficiently direct light to each eye independently.
Innovation Solution
A display system combining a waveguide and switchable grating, where the angle and position of a laser beam are controlled, and the diffractive efficiency of gratings are spatially modulated using an electric field to direct light to the left and right eyes in rapid succession, eliminating the need for spectacles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spectacles are used to block light for one eye in conventional three-dimensional displays, then light can be blocked for each eye, but flicker and discomfort occur and viewing comfort deteriorates
Solution Approach 1:
The patent applies periodic action by rapidly alternating the direction of the laser beam between left-eye and right-eye viewing paths at a frequency above the human flicker fusion threshold. This time-multiplexed approach creates the perception of simultaneous viewing for both eyes without actual flicker, resolving the contradiction between effective light blocking and viewing comfort
Solution Approach 2:
The patent uses dynamic control of the laser beam direction through a scanning mirror and dynamic modulation of grating diffractive efficiency to steer light to different eyes in rapid succession. This dynamic system replaces the static spectacle-based approach, enabling flicker-free three-dimensional viewing by continuously adapting light paths in real-time
2Object-affected harmful factors
If a waveguide with switchable grating is used to direct light to each eye independently, then spectacles are eliminated and viewing comfort improves, but device complexity increases
Solution Approach 1:
The patent merges multiple functions into a single integrated waveguide system that combines light guiding, switching, and directional control. The waveguide integrates the scanning mirror control, grating modulation, and light steering functions that would otherwise require separate components, reducing overall system complexity while maintaining viewing comfort benefits
Solution Approach 2:
The patent introduces an index-matching fluid as an intermediary mechanism to control grating switchability. By using the fluid's refractive index properties to enable or disable grating diffraction, the system achieves complex light steering functionality through a simple physical mechanism, managing device complexity while enabling independent eye-directed light control
3Measurement precision
If the diffractive efficiency of gratings is spatially modulated to control light position and angle, then precise light control for three-dimensional imaging is achieved, but manufacturing precision requirements increase
Solution Approach 1:
The patent uses dynamic control of grating diffractive efficiency through index-matching fluid modulation rather than relying on static, precisely fabricated gratings. By controlling the fluid's presence or absence, the system achieves precise light steering without requiring extremely precise grating manufacturing, as the switching function is controlled dynamically rather than through manufacturing tolerances
Solution Approach 2:
The patent changes the refractive index parameter of the medium surrounding the grating by introducing or removing index-matching fluid. This parameter change dynamically controls the grating's diffractive efficiency, enabling precise light position and angle control without requiring high manufacturing precision in the grating structure itself, as the control is achieved through optical parameter modulation rather than geometric precision
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 configuration allows for a flicker-free, three-dimensional image presentation by controlling the position, angle, and intensity of light to each eye, reducing eye strain and enhancing viewing comfort.
Implementation Method 1
light from a laser is injected via a scanner into the edge of a slab waveguide
Implementation Method 2
A spatial array of switchable gratings controllably ejects light from the waveguide
Implementation Method 3
the grating can be made switchable by using an electric field to draw index-matching fluid into a gap between the grating and the waveguide
Data Source
AI summary
A display system produces three-dimensional images. The display system includes a waveguide, and a light source that injects light into the waveguide. A switchable grating allows individual positions in the grating in a two-dimensional array to be turned on and off. A controller configured to spatially modulate the switchable grating so as to control where light exits the waveguide. An eye tracking module tracks eye position of a viewer. The controller uses the eye position to control switching of the grating.