Series MEMS Mirrors for Uniform Pixel Distribution in Near-Eye Displays
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Solution Overview
Problem
In near-eye display systems, the uneven distribution of illumination pulses or pixels across the scan pattern of resonant MEMS mirrors leads to over-saturation at the extents of the scan, resulting in inefficient power usage due to the need to turn off illumination sources during certain scan regions.
Innovation Solution
Incorporating a low-amplitude, low-frequency MEMS mirror in series with a higher-amplitude, higher-frequency resonant MEMS mirror to redistribute illumination pulses or pixels, allowing the lasers to remain energized throughout the scan range and maintaining a more even pixel distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a resonant MEMS mirror is used to scan light in a sinusoidal pattern, then the scanning speed and frequency are improved, but the pixel distribution becomes uneven with over-saturation at the scan extents
Solution Approach 1:
The patent divides the single resonant MEMS mirror into two separate MEMS mirrors: a first resonant MEMS mirror that performs high-speed sinusoidal scanning, and a second low-frequency MEMS mirror that performs redistribution scanning. This segmentation allows each mirror to have specialized functions, with the second mirror specifically designed to correct the pixel distribution issues created by the first mirror.
Solution Approach 2:
The second low-frequency MEMS mirror acts as an intermediary between the first resonant MEMS mirror and the display medium. It receives the light pattern from the first mirror and redistributes the pixels to achieve uniform distribution, effectively mediating the transition from non-uniform to uniform pixel distribution across the display area.
2Manufacturing precision
If the illumination source is turned off during certain scan regions to avoid over-saturation, then the pixel distribution uniformity is improved, but the power consumption efficiency deteriorates
Solution Approach 1:
The second low-frequency MEMS mirror serves as an intermediary redistribution device that receives light from the first mirror and redistributes pixels uniformly across the display area. This allows the illumination source to remain continuously energized while achieving uniform pixel distribution through the redistribution action of the second mirror.
Solution Approach 2:
The patent changes the operational parameters by introducing a second mirror with different scanning characteristics (lower frequency, different amplitude) to modify the overall pixel distribution pattern. By adjusting the scanning parameters of the second mirror, the system achieves uniform pixel distribution without needing to modulate the illumination source power.
3Area of stationary object
If a single high-amplitude, high-frequency resonant MEMS mirror is used, then the scanning coverage and resolution are improved, but the pixel density becomes non-uniform with clustering at scan extremes
Solution Approach 1:
The patent segments the scanning function into two distinct mirrors: the first resonant MEMS mirror provides high-speed scanning with large amplitude to achieve broad coverage, while the second low-frequency MEMS mirror provides redistribution scanning to ensure uniform pixel density. This segmentation allows each component to optimize for its specific function without compromise.
Solution Approach 2:
The patent introduces an additional spatial and temporal dimension by adding a second mirror with different scanning characteristics. The second mirror operates at a lower frequency and different amplitude, creating a superposition of scanning patterns that results in uniform pixel distribution across the entire scan area, effectively adding another degree of freedom to the scanning system.
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 achieves a more even distribution of illumination pulses or pixels across the field of view, enhancing user experience and reducing power consumption by keeping the lasers energized throughout the scan.
Implementation Method 1
a first, relatively low-amplitude, low-frequency micro-electromechanical system (MEMS) mirror to scan light across a first range of angles
Implementation Method 2
a second, higher-amplitude, higher-frequency resonant MEMS mirror to scan the light across a second range of angles
Implementation Method 3
The optical relay receives the scanned light from an initial MEMS mirror and introduces a convergence to the light (e.g., via collimation) to focus the light to a point or a line at an exit pupil plane
Implementation Method 4
The incoupler receives the light over a range of input angles, and the light propagates through the waveguide within angles acceptable to achieve total internal reflection (TIR) within the waveguide
Data Source
AI summary
A near-eye display system employs a low-amplitude, low-frequency micro-electromechanical system (MEMS) mirror in series with a higher-amplitude, higher-frequency resonant MEMS mirror to rotate at a reduced amplitude and frequency with respect to the resonant MEMS mirror redistribute illumination pulses or pixels at the extents of a sinusoidal angular scan pattern of the resonant MEMS mirror.