MEMS Resonance Control via Phase Detection
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Solution Overview
Problem
Current laser projection systems require a specially designed ASIC to maintain the white point of the projected image constant, which increases development costs due to the need for a custom ASIC for each application, and they struggle with precise control of MEMS mirrors and collimated light beams for accurate color representation.
Innovation Solution
A light projection system utilizing a graphics processing unit (GPU) to compensate for the non-linear response of the light module by processing video data, eliminating the need for a custom ASIC and enabling precise control of MEMS mirrors through phase detection and zero cross detection techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a specially designed ASIC is used to maintain constant white point, then color accuracy is improved, but development cost increases due to custom ASIC design for each application
Solution Approach 1:
The patent uses a GPU to copy and adapt general-purpose graphics processing capabilities to perform the specific function of white point compensation, replacing the need for custom ASIC design. The GPU executes shader programs that compensate for light module response variations, achieving color accuracy through software-based processing rather than custom hardware.
Solution Approach 2:
The patent employs a universal GPU that can perform multiple functions including traditional graphics rendering and the additional function of light module response compensation. This multi-functional approach eliminates the need for application-specific ASIC designs, as the same GPU hardware can serve different projection applications through software configuration.
2Measurement precision
If phase detection and zero cross detection techniques are used for MEMS mirror control, then resonance control precision is improved, but system complexity increases
Solution Approach 1:
The patent implements feedback control by detecting the phase and zero-crossing points of the MEMS mirror oscillation signal, comparing these measurements with desired resonance conditions, and adjusting the drive signal accordingly. This closed-loop feedback mechanism maintains precise resonance control while using standard detection circuits rather than complex specialized hardware.
Solution Approach 2:
The patent controls MEMS mirror resonance by adjusting the frequency and phase parameters of the drive signal based on detected zero-crossing points and phase information. By dynamically changing these electrical parameters to match resonance conditions, the system achieves precise control without requiring complex mechanical or structural modifications to the MEMS device.
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
The GPU-based system maintains a consistent white point across temperature variations, reduces development costs by using an off-the-shelf ASIC, and ensures accurate color representation and precise MEMS mirror control, enhancing the overall performance of laser projection systems.
Implementation Method 1
MEMS mirrors used in applications that utilize fast scanning rates (typically over 20 Khz) are often resonance mirrors due to the relative ease of maintaining a mirror at resonance
Implementation Method 2
obtain a first sample of the mirror sense signal at a first phase of the mirror drive signal, obtain a second sample of the mirror sense signal at a second phase of the mirror drive signal
Data Source
AI summary
A light projection system includes a MEMS mirror operating on a mirror drive signal to generate a mirror sense signal resulting from operation of the MEMS mirror based on the mirror drive signal. A mirror driver generates the mirror drive signal from a drive control signal. A controller receives the mirror sense signal from the MEMS mirror, obtains a first sample of the mirror sense signal at a first phase thereof, obtains a second sample of the mirror sense signal at a second phase thereof, wherein the first and second phases are separated by a half period of the mirror drive signal, with the second phase occurring after the first phase, and generates the drive control signal based on a difference between the first and second samples to keep the mirror drive signal separated in phase from the mirror sense signal by a desired amount of phase separation.