Reflective Prism Input Couplers for Compact Waveguide Displays
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Solution Overview
Problem
Designing electronic devices such as virtual and augmented reality headsets with optical systems that minimize bulkiness and enhance optical performance while providing a wide field of view and uniform light intensity is challenging.
Innovation Solution
The use of a reflective input coupler prism mounted to a waveguide, combined with switchable reflective layers and polarization-sensitive films, allows for expanding the field of view and increasing effective resolution by rapidly toggling between different optical states to provide a wide and uniform light distribution within the eye box.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If traditional lens systems are used to redirect light in waveguide displays, then optical performance can be achieved, but the device becomes bulky and requires more lens elements
Solution Approach 1:
The patent combines the functions of multiple optical components into a single reflective input coupling prism. The prism integrates light redirection, field of view expansion, and optical power provision that were previously requiring separate lens elements, thereby reducing device volume while maintaining optical performance
Solution Approach 2:
The reflective input coupling prism serves multiple functions simultaneously: it redirects light into the waveguide, expands the field of view, and provides optical power to the light path. This multi-functionality eliminates the need for separate dedicated components for each function, reducing overall device size
2Adaptability or versatility
If the field of view is expanded using traditional optical methods, then wider viewing angles are achieved, but the device complexity and number of components increase
Solution Approach 1:
The patent merges field of view expansion functionality into the reflective input coupling prism by configuring its reflective surfaces at specific angles. This allows the prism to simultaneously redirect light and expand the field of view without requiring separate field of view expansion components
Solution Approach 2:
The patent incorporates switchable reflective layers that can dynamically change the optical path to expand or reduce the field of view as needed. This dynamic capability allows field of view adjustment without permanently adding complex static optical components
3Adaptability or versatility
If switchable reflective layers are used to expand field of view, then viewing angles increase, but processing power consumption increases
Solution Approach 1:
The patent replaces electronically controlled switching mechanisms with optically switchable reflective layers that can be toggled using optical signals or mechanical actuation. This substitution reduces the need for continuous electronic processing and power consumption while maintaining field of view expansion capability
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 reduces the number of lens elements required, minimizes device size, and enhances optical performance by providing a wider field of view and uniform light intensity without increasing processing power consumption.
Implementation Method 1
The prism may receive the light from the lens through the waveguide and may have a reflective surface that reflects the light into the waveguide
Implementation Method 2
The reflective surface may be curved to provide the reflected light with an optical power
Implementation Method 3
The input coupler may redirect light from the display module so that the light propagates in the waveguide towards the output coupler
Implementation Method 4
A polarization-sensitive film may be provided on the first reflective surface and may reflect a first polarization of light while transmitting a second polarization of light
Data Source
AI summary
An electronic device may include a display module that generates light and an optical system that redirects the light towards an eye box. The system may include an input coupler on a waveguide and a lens that directs the light towards the input coupler. The input coupler may include a prism having a reflective surface that reflects the light into the waveguide. The reflective surface may be curved to provide the light with an optical power. The prism may be configured to expand a field of view of the light. A birefringent beam displacer may expand the effective pupil size of the light. The lens may include lens elements that converge the light at a location between the lens elements and the waveguide. A switchable panel may be placed at the location and toggled between first and second orientations to increase the effective resolution of the light.