MEMS Mirror Scanning Device Frequency Modulation
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Solution Overview
Problem
Existing scanning devices with MEMS mirror mechanisms face instability due to variations in ambient temperature affecting the resonance frequency, leading to deviations in the corresponding relationship between horizontal and vertical drive signals, which can result in unstable image display.
Innovation Solution
A scanning device with a control unit that generates multiple second signal elements corresponding to a single first signal element, allowing for precise control of the second drive signal and frequency modulation to match the resonance frequency, thereby stabilizing the scanning process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If synchronization is performed at the time of initiating one frame and at the time of terminating one frame between horizontal and vertical drive signals, then the scanning device can operate with simple control logic, but when resonance frequency varies due to temperature changes, deviation in corresponding relationship between drive signals cannot be corrected, leading to unstable image display
Solution Approach 1:
The patent applies periodic action by dividing the vertical drive signal into multiple periodic second signal elements that correspond to periodic first signal elements in the horizontal drive signal. This periodic structure allows for continuous synchronization correction throughout the frame period, not just at beginning and end, thereby maintaining stable corresponding relationships between drive signals even when resonance frequency varies due to temperature changes.
Solution Approach 2:
The patent implements feedback by continuously monitoring the corresponding relationship between horizontal and vertical drive signals and adjusting the second drive signal based on detected deviations. The control unit compares the timing and position information from both drive signals and dynamically corrects synchronization errors, ensuring stable image display despite resonance frequency variations.
2Device complexity
If one second signal element corresponds to one first signal element, then the control structure is simpler, but the waveform control precision is insufficient to compensate for resonance frequency variations
Solution Approach 1:
The patent applies segmentation by dividing one second signal element into multiple smaller second signal elements (N pieces) that correspond to first signal elements. This segmentation increases the resolution of waveform control, allowing for more precise adjustment of the vertical drive signal to compensate for resonance frequency variations. The multiple segmented signal elements provide finer granularity for synchronization correction.
Solution Approach 2:
The patent implements parameter changes by dynamically adjusting the timing, duration, and amplitude parameters of the multiple second signal elements based on the detected resonance frequency variations. This allows the waveform characteristics of the vertical drive signal to be continuously optimized to maintain accurate synchronization with the horizontal drive signal despite environmental changes.
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
This approach ensures stable scanning and image display by minimizing deviations between drive signals, even when the resonance frequency varies, and allows for finer control of the waveform, reducing the risk of flicker phenomena.
Implementation Method 1
an MEMS mirror mechanism 3 that includes a mirror 3a that reflects the laser light emitted from the light source
Implementation Method 2
a control unit 5 that generates a first drive signal for swinging the mirror with respect to the first axial line as a central line and a second drive signal for swinging the mirror with respect to the second axial line as a central line
Data Source
AI summary
A scanning device includes an MEMS mirror mechanism that swings a mirror with respect to a first axial line as a central line and swings the mirror with respect to a second axial line as a central line, and a control unit that generates a first drive signal for swinging the mirror with respect to the first axial line as a central line and a second drive signal for swinging the mirror with respect to the second axial line as a central line. In a lighting-on period in which a light source emits laser light in one swing of the mirror with respect to the second axial line as a central line, the control unit generates the first drive signal and the second drive signal by repeating a process of generating N pieces (N is an integer of two or greater) of second signal elements which respectively constitute the second drive signal with respect to a first signal element in a ½ cycle period in the first drive signal.