Resonance-Lock Controller for Variable Focal Length Lens

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Solution Overview

Problem

Variable focal length lens devices face instability in resonance-lock control due to changes in resonance frequency caused by temperature fluctuations, leading to inefficiencies in forming standing waves, as the existing methods struggle to accurately determine the direction of frequency adjustments based on drive current changes.

Innovation Solution

Implementing a resonance-lock controller that tunes the drive signal frequency to a peak position of the voltage-current phase difference between the drive signal voltage and current, and adjusts the frequency based on changes in this phase difference to maintain resonance-lock control, thereby stabilizing the operation at the resonance frequency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the drive signal frequency is not tuned to the resonance frequency of the lens system, then the system can operate without frequency adjustment, but the standing wave formation becomes inefficient and resonance-lock control fails

Engineering Contradiction:

Improveresonance-lock control stabilityVSAvoidfrequency adjustment mechanism

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements a feedback mechanism where the resonance-lock controller continuously monitors the voltage-current phase difference and automatically adjusts the drive signal frequency to maintain resonance-lock control. The controller detects phase difference changes and adjusts the frequency accordingly, creating a closed-loop control system that ensures reliable resonance-lock control while operating in a temperature-variable environment.

Inventive Principle:

Principle #23Feedback

2Adaptability or versatility

If the resonance frequency changes due to temperature fluctuations, then the system adapts to new conditions, but the existing drive signal frequency becomes mismatched and resonance-lock control fails

Engineering Contradiction:

Improvetemperature adaptation capabilityVSAvoidresonance-lock control stability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent employs a dynamic frequency adjustment mechanism that allows the drive signal frequency to change in real-time based on temperature variations and resonance frequency shifts. The resonance-lock controller dynamically tunes the frequency by detecting voltage-current phase difference changes and adjusting the drive signal accordingly, enabling the system to adapt to temperature fluctuations while maintaining reliable resonance-lock control.

Inventive Principle:

Principle #15Dynamics

3Measurement precision

If the voltage-current phase difference is used for frequency adjustment, then the resonance-lock control accuracy improves, but the control system complexity increases

Engineering Contradiction:

Improvefrequency tuning accuracyVSAvoidcontrol system structure

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical frequency adjustment mechanisms with an electronic control system that uses voltage-current phase difference detection. The resonance-lock controller electronically adjusts the drive signal frequency based on phase difference measurements, substituting mechanical tuning with electronic control to achieve high frequency tuning accuracy while minimizing structural complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 resonance-lock control by accurately determining frequency adjustments, reducing the likelihood of failure in locking to the peak position and maintaining efficient operation of the variable focal length lens device despite changes in resonance frequency.

Implementation Method 1

a cylindrical oscillator made of a piezoelectric material that is immersed in a transparent liquid. When an alternating-current (AC) voltage is applied to an inner circumferential surface and an outer circumferential surface of the oscillator of the lens system, the oscillator expands and contracts in a thickness direction thereof to oscillate the liquid inside the oscillator

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

when the frequency of the applied AC voltage is tuned to an intrinsic frequency of the liquid, a concentric standing wave is created in the liquid to form concentric regions of different refractive indexes around a center axis of the oscillator

Methodology Applied

Scientific EffectStanding wave resonance: Resonance

Implementation Method 3

when light is introduced into the oscillator of the lens system along the center axis of the oscillator, the light follows a diverging or converging path according to the refractive index of each of the concentric regions

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentUS10908398B2Variable focal length lens device and variable focal length lens control method

Publication Date: 2021.02.02 MITUTOYO CORP

AI summary

A variable focal length lens device includes: a lens system whose refractive index changes in accordance with an inputted drive signal; and a resonance-lock controller that locks the drive signal to a resonance frequency of the lens system. The resonance-lock controller tunes a frequency of the drive signal to a peak position of a voltage-current phase difference between a voltage of the drive signal and a drive current of the lens system, and raises or lowers the frequency of the drive signal in accordance with the drive current when the voltage-current phase difference changes.