Waveguide Light Turning Gaps for Near-Eye Displays
Solution Overview
Problem
Manufacturing durable waveguides for displays, especially near-eye displays, is challenging due to the fragility and limited angle range of multi-layer dichroic mirrors, which are difficult to produce and costly, limiting their use in larger sizes.
Innovation Solution
A waveguide made from optically transparent material with gaps along its length, where these gaps act as partial reflectors and transmitters, allowing for precise control of light angles and eliminating the need for optical coatings, enabling simpler manufacture and wider angle usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multi-layer dichroic mirrors are used to turn light in the waveguide, then light can be reflected at multiple positions, but the mirrors are fragile, difficult to manufacture, and limited in angle range
Solution Approach 1:
The patent removes the complex multi-layer dichroic mirror coatings from the waveguide structure and replaces them with simple geometric gaps. This extraction of the problematic component eliminates manufacturing complexity while maintaining the light-turning function through total internal reflection at the gaps.
Solution Approach 2:
The patent changes the physical parameter of the reflecting surface from a coated continuous surface to a gapped surface with specific geometrical parameters (gap width, orientation, spacing). This parameter change enables simpler manufacturing while achieving the desired light control through geometric optics rather than optical coatings.
2Adaptability or versatility
If multi-layer dichroic mirrors are used, then light reflection is achieved, but the mirrors are limited in the range of angles they can handle
Solution Approach 1:
Instead of using optical coatings to control reflection angles, the patent inverts the approach by using the absence of material (gaps) with specific geometrical orientations to control light paths. This inversion allows a broader angle range because total internal reflection occurs at the gaps regardless of the specific coating properties.
3Manufacturing precision
If precise multiple optical coatings are applied to create mirrors, then light reflection is controlled, but manufacturing becomes difficult and costly
Solution Approach 1:
The patent replaces the mechanical/optical system of applying precise multi-layer coatings with a geometrical system of creating gaps through cutting, molding, or etching. This substitution eliminates the need for complex coating equipment and processes while achieving precise light control through geometric parameters that are easier to manufacture.
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
The solution provides a durable and cost-effective waveguide that can handle a wider range of angles, reducing manufacturing complexity and improving light control, suitable for various display sizes, including near-eye and large displays.
Implementation Method 1
Each gap of each joining surface reflects out of the waveguide light received by the gap within a first angle range, and each gap of each joining surface passes for total internal reflection down the waveguide light received within a second angle range
Data Source
AI summary
The technology provides embodiments for a waveguide including gaps which turn the direction of light. Each of a plurality of planes (202a, 202b) located within a waveguide (123) includes a group of gaps (250) so that each of the gapped planes partially reflects out of the waveguide light within a first angle range and transmits down the waveguide light received within a second angle range. In some examples, the waveguide is formed by joining optically transparent sections, and each group of gaps is formed in a surface of each optically transparent section which becomes a joining surface when bonded with an abutting all flat surface of an adjacent section. The waveguide may be used in displays, and in particular in near-eye displays (NED)s.