MEMS Headlight Mirror Resonant Scanning Offset Control
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Solution Overview
Problem
Conventional headlight devices with MEMS light deflectors struggle to adjust the center turning angle effectively when the mirror unit is reciprocally turned at its resonant frequency, leading to issues with maintaining a consistent irradiation region, especially when the vehicle travels along a curved road, causing the irradiation region to be outside the road or not align with the target.
Innovation Solution
The headlight device employs two irradiation systems with a non-resonant control unit that generates a second driving voltage to displace the second irradiation region horizontally within the first irradiation region, ensuring a constant irradiation area by superimposing light from both systems, and includes a situation detection unit to adjust the offset voltage based on the vehicle's driving situation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the mirror unit is reciprocally turned at its resonant frequency to achieve stable high-frequency turning, then the stability of the mirror unit is improved, but the ability to adjust the center turning angle is lost
Solution Approach 1:
The patent divides the irradiation system into two independent irradiation systems (first and second), each with its own mirror unit and actuator. The first mirror unit operates at resonant frequency for stable high-speed scanning, while the second mirror unit operates non-resonantly to enable center turning angle adjustment. This segmentation allows each subsystem to optimize for its specific function without compromising the other.
Solution Approach 2:
The patent changes the operating parameters of the two mirror units differently: the first mirror unit operates at resonant frequency (high frequency) while the second operates at non-resonant frequency (low frequency). Additionally, the second actuator applies an offset voltage to shift the center turning angle, a parameter adjustment that would be difficult when operating at resonant frequency alone.
2Adaptability or versatility
If the scanning region is displaced horizontally to align with the road on curved paths, then the adaptability to curved road conditions is improved, but the structure of the light deflector becomes complicated
Solution Approach 1:
The patent segments the horizontal displacement function between two mirror units: the first mirror unit provides the primary scanning motion at resonant frequency, while the second mirror unit provides the additional horizontal displacement for center turning angle adjustment. This segmentation avoids the need for a single complex light deflector structure that would require turning the entire assembly.
Solution Approach 2:
The patent merges the functions of two irradiation systems into a single headlight device, where the first and second irradiation systems work together to achieve both high-speed scanning and horizontal displacement. The control unit coordinates both systems to produce the desired combined irradiation pattern, effectively combining resonant and non-resonant operations.
3Device complexity
If a single irradiation system is used to maintain a fixed irradiation region, then the device complexity is reduced, but the ability to maintain consistent irradiation on curved roads deteriorates
Solution Approach 1:
The patent segments the irradiation function into two systems with different characteristics: the first irradiation system provides stable high-frequency scanning for normal operation, while the second irradiation system provides low-frequency adjustment capability for curved road conditions. This segmentation enables the device to handle both straight and curved road scenarios effectively.
Solution Approach 2:
The patent introduces dynamic adjustability through the second irradiation system, which can modify the irradiation region in real-time based on driving conditions. The control unit dynamically adjusts the center turning angle of the second mirror unit to maintain the irradiation region within the road boundaries during curved path travel.
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 configuration allows for smooth reciprocal turning of the mirror unit about the second rotation axis, maintaining a consistent irradiation region even when the vehicle is on a curved road, ensuring the target remains within the irradiation area.
Implementation Method 1
an actuator configured to turn the mirror unit about the first and second rotation axes
Data Source
Figure 1
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AI summary
A headlight device (1) provided enables horizontally displacing of the irradiation region (SPOT) for scanning of scanning light (22b) by a light deflector (15b) without problems. The light deflector (15b) includes: a mirror unit that reciprocally turns about first and second rotation axes at first and second frequencies. The first frequency is a natural-oscillation frequency of the mirror unit, and the second frequency is lower than the first frequency. Directions of the first and second rotation axes are set so that scanning directions of the reflected light (23b) due to the reciprocal turning of the mirror unit about the first and second rotation axes are in the directions of vertical axis and horizontal axis, respectively. The control unit (57) controls reciprocal turning of the mirror unit about the second rotation axis based on driving voltage obtained by superimposing offset voltage with basic driving voltage having an increasing and decreasing waveform.