Resonant Mirror Drive Circuit Using LC Amplification to Cut Power Loss
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Solution Overview
Problem
Existing drive circuits for resonant scanning mirrors in mobile display devices face inefficiencies due to high AC voltage requirements, large size, and potential damage from excessive voltage swings, particularly when using boost converters and H-bridges.
Innovation Solution
A linear LC resonant driving scheme is employed to convert DC voltage to AC voltage efficiently, using a drive circuit with a buffer stage and coupled inductors to amplify signals only at the resonant frequency, reducing size and enhancing reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If boost converters and H-bridges are used to generate high AC voltage, then the resonant scanning mirror can be driven at resonant frequency, but the circuit size increases and power loss increases
Solution Approach 1:
The patent employs resonant vibration principles by tuning the LC circuit to match the mechanical resonant frequency of the scanning mirror. This allows the system to achieve the required AC voltage amplitude through resonant amplification rather than using high-power switching circuits, thereby reducing circuit size and power loss while maintaining effective mirror driving capability.
Solution Approach 2:
The patent changes the operating parameters by using variable inductors and capacitors to tune the resonant frequency of the LC circuit. This allows the system to adapt to different mirror resonant frequencies and achieve efficient operation at resonance without requiring complex high-voltage switching circuitry, thus reducing overall device complexity.
2Power
If boost converters and H-bridges are used to generate high AC voltage, then the resonant scanning mirror can be driven at resonant frequency, but power loss increases
Solution Approach 1:
By utilizing resonant vibration, the LC circuit naturally amplifies the voltage at the resonant frequency of the scanning mirror. This resonant amplification effect allows the system to achieve the necessary high AC voltage with minimal input power, avoiding the significant power losses associated with boost converters and H-bridge circuits.
Solution Approach 2:
The patent employs periodic sinusoidal excitation at the resonant frequency of the LC circuit. This periodic action sustains the resonant oscillations, allowing continuous high-voltage output with minimal energy input, thereby dramatically reducing power loss compared to non-resonant switching approaches.
3Power
If high AC voltage is applied to the scanning mirror, then the mirror can be driven effectively, but the mirror may be damaged from excessive voltage swings
Solution Approach 1:
The patent incorporates feedback mechanisms through the resonant LC circuit that naturally limit voltage swings. The resonant circuit's impedance characteristics provide automatic voltage regulation, preventing excessive voltage excursions that could damage the mirror while ensuring sufficient drive voltage for effective operation.
Solution Approach 2:
The resonant LC circuit acts as a buffer that smooths and limits voltage swings before they reach the scanning mirror. The circuit's natural resonance characteristics prevent sharp voltage peaks and excessive swings, providing protective cushioning that preserves mirror reliability while maintaining effective drive voltage.
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 solution provides a compact, power-efficient drive circuit that minimizes exposure to high AC voltages, increasing reliability and reducing power loss, while maintaining efficient operation.
Implementation Method 1
a resonant LC stage configured to amplify the drive signal for provision to the mirror drive element. The resonant LC stage may include a coupled inductor and may utilize a parasitic capacitance of the scanning mirror system
Implementation Method 2
The first resonant LC stage may comprise a first winding of a coupled inductor, and the second resonant LC stage may comprise a second winding of the coupled inductor
Data Source
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AI summary
Examples are disclosed herein that relate to driving a resonant scanning mirror system using a linear LC resonant driving scheme. In one example, a resonant scanning mirror system includes a scanning mirror, first and second mirror drive elements, and a drive circuit to drive the scanning mirror at a resonant frequency. The drive circuit includes one or more signal sources configured to create a first source signal and a second source signal that is 180 degrees out of phase with the first source signal. The drive circuit further includes a buffer stage configured to receive the first and second source signals and output first and second drive signals, a first resonant LC stage configured to amplify the first drive signal for provision to the first mirror drive element, and a second resonant LC stage configured to amplify the second drive signal for provision to the second mirror drive element.