Scanning Mirror for Compact AR Display
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Solution Overview
Problem
Current augmented reality systems face challenges in miniaturization and energy efficiency due to the size and energy consumption of image generating components, necessitating the development of more compact and efficient display technologies.
Innovation Solution
The use of highly miniaturized display assemblies incorporating a scanning mirror configured to rotate about multiple axes, combined with optical fibers and an input coupling grating, and a monocrystalline substrate with a mirror support region that rotates using magnetic and piezoelectric actuators, to efficiently direct and modulate light for augmented reality applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If traditional 2D focal plane array light modulators are used, then image quality can be maintained, but device size and energy consumption increase
Solution Approach 1:
The patent extracts the light modulation function from traditional 2D focal plane arrays and implements it through a 1D array of light modulators combined with a scanning mechanism. This separation allows the modulation function to be maintained while significantly reducing the spatial footprint of the display assembly, directly resolving the contradiction between image quality and device size.
Solution Approach 2:
The invention introduces dynamic scanning motion to redirect light from a reduced 1D modulator array across the full display field. By making the light path dynamic through controlled reflection at different angles, the system achieves complete image coverage with fewer static modulators, thereby reducing device volume while maintaining image quality.
2Adaptability or versatility
If traditional display assemblies are used, then display functionality is achieved, but energy consumption increases
Solution Approach 1:
The patent employs periodic scanning motion of the light modulators to refresh the displayed image across the field of view. This time-multiplexed approach allows a reduced number of active modulators to service the entire display area through repeated scanning cycles, significantly lowering the total energy consumption compared to simultaneously activating all pixels in traditional 2D arrays.
3Volume of moving object
If compact display assemblies are implemented, then device portability improves, but optical alignment complexity increases
Solution Approach 1:
The patent designs the light modulator assembly to perform multiple functions: light modulation, angular redirection, and field-of-view control all through a single integrated scanning mechanism. This multi-functionality reduces the need for separate alignment components and simplifies the overall optical train, counteracting the increased alignment complexity that might otherwise result from compact integration.
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 enables the creation of compact, energy-efficient display systems that can project high-quality images while reducing the overall thickness and energy consumption of augmented reality devices, enhancing user experience and device portability.
Implementation Method 1
light emitted from the light emitting end is refracted through at least a portion of the optical element
Implementation Method 2
reflected off the scanning mirror, refracted back through the optical element and into the input coupling grating
Implementation Method 3
an electromagnetic coil disposed on the mirror support region and being configured to emit a second magnetic field that interacts with the first magnetic field to induce rotation of the mirror support region
Implementation Method 4
a mirror support region coupled to the peripheral region by a first flexure and a second flexure, the mirror support region being configured to rotate relative to the peripheral region about a first axis of rotation defined by the first and second flexures
Data Source
AI summary
A display assembly suitable for use with a virtual or augmented reality headset is described and includes the following: an input coupling grating; a scanning mirror configured to rotate about two or more different axes of rotation; an optical element; and optical fibers, each of which have a light emitting end disposed between the input coupling grating and the scanning mirror and oriented such that light emitted from the light emitting end is refracted through at least a portion of the optical element, reflected off the scanning mirror, refracted back through the optical element and into the input coupling grating. The scanning mirror can be built upon a MEMS type architecture.