Oscillating Mirror Phase Error Control Using Sense Signal Sampling
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Solution Overview
Problem
Precise control of the phase error between the drive signal and the opening angle of oscillating mirrors in MEMS devices is challenging, especially in high-definition video applications, due to non-constant phase differences, which affects synchronization with light beams and image projection accuracy.
Innovation Solution
An electronic device with a mirror controller that includes a phase error calculation block to determine the phase error between the mirror sense signal and the drive signal by sampling at specific time intervals, generating an error signal, and a phase correction block to produce a control signal for the oscillating mirror, allowing for precise phase correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional phase detection methods are used, then the system can operate with simpler components, but the phase error control precision is insufficient for high-definition video applications
Solution Approach 1:
The patent replaces complex hardware-based phase detection methods with a digital signal processing approach. By using a mirror sense signal and performing digital comparisons of signal values at specific time intervals (one quarter of the oscillation period), the system achieves high phase error measurement precision without requiring additional complex physical components like piezoresistive devices.
Solution Approach 2:
The system uses the existing mirror sense signal, which is already generated by the oscillating mirror system, to detect phase errors. Instead of requiring separate external sensing components, the system leverages the inherent feedback signal from the mirror's oscillation to perform self-diagnosis and self-correction of phase errors through digital processing.
2Measurement precision
If additional components like piezoresistive devices are used for phase detection, then measurement precision improves, but device complexity and cost increase
Solution Approach 1:
The patent eliminates the need for additional physical sensing components by substituting them with a digital signal processing method. The phase error is determined by comparing values of the existing mirror sense signal at time intervals of one quarter of the expected oscillation period, achieving high measurement precision without adding piezoresistive devices or other complex hardware.
Solution Approach 2:
Instead of using physical sensors to detect mirror position, the system creates a digital representation of the phase error by sampling and comparing the mirror sense signal at specific time points. This digital copy of the phase information is then used for correction without requiring physical intervention from additional components.
Data Source
AI summary
Disclosed herein is a mirror controller for an oscillating mirror. The mirror controller includes a processor configured to receive a mirror sense signal from the oscillating mirror and to determine a phase error between the mirror sense signal and a mirror drive signal. The processor determines the phase error by sampling the mirror sense signal at a first time, sampling the mirror sense signal at a second time at which the mirror sense signal is expected to be equal to the mirror sense signal as sampled at the first time, and generating the phase error as a function of a difference between the sample of the mirror sense signal at the second time and the sample of the mirror sense signal at the first time.