Lissajous Scanning Mirror Control Device for Image Distortion Reduction
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Solution Overview
Problem
In Lissajous scanning, deviations between the origin position indicated by the origin signal and the actual scanning position can occur, leading to deviations between the scanning period and light emission timing, resulting in image distortion.
Innovation Solution
A control device that measures elapsed times from reference points for deflection angles about two axes, stores intensity information correlating these times with signal intensities, and uses this information to control light emission timing, thereby synchronizing scanning periods with light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If Lissajous scanning is performed using an origin signal to define the scanning period, then the scanning range is increased due to large deflection angles, but a deviation occurs between the origin position indicated by the origin signal and the actual scanning position, causing image distortion
Solution Approach 1:
The system measures the actual elapsed time from reference points on the movable mirror and uses this feedback to correct the light emission timing. The correction amount is calculated based on the difference between expected and actual timing, and this correction is applied to synchronize light emission with the actual scanning position, eliminating image distortion while maintaining the large scanning range enabled by Lissajous scanning
Solution Approach 2:
The system changes the timing parameter of light emission dynamically based on the measured elapsed time from reference points. By adjusting the light emission timing according to the actual scanning mirror position, the system compensates for deviations between the origin signal and actual scanning position, resolving the position accuracy issue while preserving the expanded scanning range
2Productivity
If the movable mirror is resonantly driven by two sine waves with different frequencies to perform Lissajous scanning, then the scanning efficiency is improved, but a deviation occurs between the scanning period and light emission timing, resulting in significant image distortion
Solution Approach 1:
The system continuously measures the elapsed time from reference points on the resonantly driven movable mirror and uses this feedback to correct the light emission timing. This ensures that even during efficient resonant Lissajous scanning, the light emission remains synchronized with the actual scanning position, preventing image distortion while maintaining high scanning efficiency
Solution Approach 2:
The system replaces the mechanical timing synchronization method with a measurement and correction approach. Instead of relying solely on the origin signal generated by the resonant driving mechanism, the system measures the actual elapsed time from reference points and uses this information to correct the light emission timing, ensuring accuracy during high-speed resonant scanning
3Device complexity
If the origin signal generation portion generates the origin signal to define the Lissajous scanning period, then the scanning control is simplified, but the deviation between the origin position and actual scanning position cannot be detected or corrected
Solution Approach 1:
The system adds a feedback mechanism that measures the actual elapsed time from reference points on the movable mirror and compares it with the expected timing based on the origin signal. This feedback enables detection and correction of deviations between the origin position and actual scanning position, improving synchronization accuracy while maintaining relatively simple control through the use of reference point detection and elapsed time measurement
Data Source
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AI summary
A control device includes a first measurement portion that measures, as a first elapsed time, an elapsed time from a first reference point at which a deflection angle of a movable mirror about a first axis becomes equal to a first reference angle, a second measurement portion that measures, as a second elapsed time, an elapsed time from a second reference point at which a deflection angle of the movable mirror about a second axis becomes equal to a second reference angle, an information storage portion in which intensity information representing a correspondence relationship between the first elapsed time and the second elapsed time, and a signal intensity of the input image is stored, a readout portion that reads out the signal intensity corresponding to the first elapsed time measured by the first measurement portion and to the second elapsed time measured by the second measurement portion from the information storage portion, and a light emission control portion that causes a light emitting device to perform the intensity modulation of the light based on the signal intensity read out by the readout portion.