Micromirror Abnormality Detection via Position Signal Fluctuations
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Solution Overview
Problem
Existing optical scanning devices, such as those used in LiDAR and HUD systems, face challenges in detecting abnormal operations of micromirrors at high speeds, as current methods require acquiring and evaluating waveforms over one swing period, leading to slow detection of amplitude deviations.
Innovation Solution
An optical scanning device comprising a micromirror device, a control device, a light irradiation device, a detection device, and an abnormality detection device that uses temporal fluctuations in position signals to detect abnormal operations, with a position sensitive detector and a differential amplification circuit to determine deviations within specific time intervals, enabling rapid detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the amplitude of the mirror is monitored by acquiring and evaluating a waveform for one swing period, then the abnormal operation can be detected, but the detection speed is slow
Solution Approach 1:
The patent segments the swing period into multiple time intervals and processes position signals from each interval independently. Instead of waiting for one complete swing period to detect abnormalities, the system divides the period into segments and evaluates each segment separately, enabling faster detection of amplitude deviations without compromising reliability
Solution Approach 2:
The patent accumulates position signals from multiple time intervals in advance and performs comparative evaluation before a complete swing period elapses. By preparing the data structure and performing preliminary calculations on accumulated signals, the system can quickly determine when amplitude falls outside the predetermined range, achieving both high speed and high reliability
2Speed
If the mirror operation is monitored continuously, then abnormal operations can be detected quickly, but the system complexity increases
Solution Approach 1:
The patent introduces a position signal as an intermediary that indirectly reflects mirror amplitude. Instead of directly measuring mirror position at multiple points, the system uses a single position signal from a light-receiving element that varies with mirror amplitude. This intermediary approach enables continuous monitoring without adding complex direct measurement mechanisms
Solution Approach 2:
The patent implements a feedback mechanism where the position signal is continuously compared against accumulated signals from previous time intervals. The abnormality detection device uses this feedback loop to automatically determine when amplitude deviations occur, maintaining simple hardware while achieving continuous monitoring through intelligent signal processing
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
Enables high-speed detection of abnormal mirror operations by analyzing position signal fluctuations, improving detection speed and accuracy while minimizing false positives and negatives.
Implementation Method 1
a light irradiation device configured to irradiate a back surface of the mirror on a side opposite to the reflecting surface with illumination light; a detection device to which reflected light of the illumination light that has been reflected by the mirror is incident
Implementation Method 2
the detection device is a position sensitive detector capable of detecting a light quantity centroid position of the incidence light
Data Source
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AI summary
Provided are an optical scanning device and an abnormality detection method with which an abnormal operation of a mirror can be detected at high speed during the operation. An optical scanning device of the present disclosure includes: a micromirror device including a mirror that has a reflecting surface for reflecting light and is swingable around at least one axis, and an actuator that allows the mirror to swing; a control device configured to control an operation of the actuator; a light irradiation device configured to irradiate a back surface of the mirror on a side opposite to the reflecting surface with illumination light; a detection device to which reflected light of the illumination light that has been reflected by the mirror is incident and configured to output a position signal representing a position of the incidence light; and an abnormality detection device configured to detect an abnormal operation of the mirror based on a temporal fluctuation amount of the position signal.