Scanning Mirror Control for Non-Rectangular Display Distortion
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Solution Overview
Problem
Controlling the deflection of scanning mirrors in scanning beam display systems to produce accurate angular motion and maintain a rectangular field of view is challenging due to high mechanical gain and non-linear characteristics, which result in motion distortion.
Innovation Solution
A feedback loop system that modifies scanning mirror drive signals by adapting the amplitude and phase of harmonic signals, using LMS tone adders and harmonic coefficient weighting arrays, to account for resonant characteristics and mechanical gain variations, ensuring precise mirror deflection and minimizing distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional scanning mirror control is used, then the system is simple to operate, but motion distortion occurs due to high mechanical gain and non-linear characteristics
Solution Approach 1:
The patent implements a feedback control system that measures the actual mirror deflection and compares it with the desired deflection, then adjusts the drive signals accordingly. This closed-loop approach compensates for non-linear characteristics and mechanical gain variations, achieving accurate mirror control while managing system complexity through systematic error correction.
Solution Approach 2:
The patent dynamically adjusts drive signal parameters including amplitude and phase of harmonic signals to account for resonant characteristics and mechanical gain variations. By changing these parameters in real-time based on measured system response, the system achieves precise mirror deflection control despite non-linear mechanical behavior.
2Manufacturing precision
If harmonic coefficient weighting arrays are used to account for resonant characteristics, then mirror deflection accuracy is improved, but control algorithm complexity increases
Solution Approach 1:
The patent pre-calculates and stores harmonic coefficient weighting arrays that account for resonant characteristics and mechanical gain variations. These pre-computed coefficients are then applied during operation to simplify real-time control while maintaining high precision mirror positioning, reducing the computational burden during active scanning.
Solution Approach 2:
The patent modifies the amplitude and phase parameters of harmonic drive signals using weighting coefficients that are optimized to match the specific resonant characteristics of the scanning mirror system. This parameter optimization allows the system to achieve accurate mirror deflection while managing algorithmic complexity through targeted parameter adjustment rather than full-system reconfiguration.
3Adaptability or versatility
If fast-scan amplitude variations are implemented, then non-rectangular display shapes are achieved, but uniform scan angle amplitude is lost
Solution Approach 1:
The patent applies different amplitude variations to different regions of the scan pattern, allowing non-uniform fast-scan amplitudes in specific areas while maintaining uniform scan angles in other regions. This local differentiation enables flexible display shape control for specific applications while preserving overall scan uniformity where required.
Solution Approach 2:
The patent dynamically adjusts fast-scan amplitude based on the desired display shape requirements, transitioning between uniform and non-uniform scan patterns as needed. This dynamic adaptation allows the system to optimize between rectangular and non-rectangular display shapes while managing the trade-off with scan angle uniformity through real-time parameter modification.
Data Source
AI summary
A scanning beam projection system includes a scanning mirror having a fast-scan axis and a slow-scan axis. Movement on the fast-scan axis is controlled by a fast-scan scanning mirror control system. The control system receives position information describing angular displacement of the mirror. A fast-scan drive signal is generated that causes the scanning mirror to oscillate at a resonant frequency with a varying amplitude.