Scanning Mirror Noise-Threshold Control for Jitter Reduction
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Solution Overview
Problem
Scanning display devices experience undesired jitter in scanning mirror trajectories due to noise distortions in the feedback signal, leading to visible artifacts in the displayed image.
Innovation Solution
Implement a noise threshold condition to filter out noise in the control parameter before adjusting the scanning mirror trajectory, using a drive signal to maintain a desired trajectory by comparing the control parameter to a noise threshold condition and adjusting the drive signal only when the threshold is met.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the scanning mirror trajectory is continuously adjusted based on feedback signal, then the mirror positioning accuracy is improved, but noise distortions in the feedback signal cause undesired jitter and visible artifacts
Solution Approach 1:
A noise threshold condition is introduced as an intermediary between the feedback signal and the mirror trajectory adjustment. The controller compares the control parameter against the noise threshold before applying corrections, filtering out noise-induced variations while preserving genuine positioning deviations that require correction.
Solution Approach 2:
The system dynamically changes the response behavior based on the control parameter value relative to the noise threshold. When the control parameter exceeds the threshold, trajectory adjustment is enabled; when it remains below the threshold, adjustment is suppressed, effectively adapting the system's sensitivity to the current noise conditions.
2Reliability
If the drive signal is adjusted frequently to correct trajectory deviations, then the image quality is improved, but noise in the feedback signal causes unnecessary adjustments and increases system instability
Solution Approach 1:
The system employs a threshold-based feedback mechanism where the drive signal adjustment is contingent upon the control parameter exceeding the noise threshold condition. This feedback structure ensures that corrections are only applied when genuine positioning errors are detected, rather than responding to noise fluctuations, thereby maintaining system stability while improving image quality.
Solution Approach 2:
Instead of continuously adjusting the drive signal in response to every feedback variation, the system applies partial action by only adjusting the signal when the control parameter exceeds the noise threshold. This selective adjustment approach prevents over-correction and unnecessary signal changes that would destabilize the system.
Data Source
AI summary
One example provides a method enacted on a scanning display device comprising an illumination source, and a scanning mirror system including a sense circuit coupled to a scanning mirror. The method comprises operating the scanning mirror system using a drive signal while operating the illumination source to thereby project an image, obtaining a control parameter based at least upon an output of the sense circuit, and comparing the control parameter to a noise threshold condition. The method further comprises, when the control parameter does not meet the noise threshold condition, continuing operating the scanning mirror according to the drive signal. The method also comprises, when the control parameter meets the noise threshold condition, adjusting the drive signal to form an adjusted drive signal to change a trajectory of the scanning mirror.