Liquid Crystal Lens Overdrive Voltage Control
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Solution Overview
Problem
Existing electrically-tunable lenses struggle to dynamically adjust focal power and optical center in response to varying angles of incidence and distances, leading to suboptimal performance in adaptive optics applications.
Innovation Solution
The development of an optical device with an electro-optical layer and conductive electrodes, where control circuitry applies voltage waveforms to generate phase modulation profiles that adjust focal power and optical center based on the angle of incidence and distance, using overshoot and undershoot control voltages to reduce switching latency and improve focal power transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional voltage control is used to adjust focal power in liquid crystal lenses, then the lens can change focal length, but the switching latency is excessive and transition speed is slow
Solution Approach 1:
The patent applies overdrive voltage (a voltage higher than the target voltage) before the actual focal power transition to pre-excite the liquid crystal molecules. This preliminary action causes the molecules to start rotating in the desired direction before the actual transition begins, significantly reducing the switching latency and accelerating the focal power transition speed.
Solution Approach 2:
The patent employs a multi-stage voltage waveform that applies different voltages in sequential time periods: first an overdrive voltage for a predetermined time, then a target voltage, and optionally an undershoot voltage. This periodic action pattern optimizes the transition by providing strong initial drive followed by stabilization, achieving fast switching without excessive overshoot.
2Speed
If voltage is increased to accelerate liquid crystal response, then switching speed improves, but focal power precision deteriorates due to overshoot and instability
Solution Approach 1:
The overdrive voltage is applied for a predetermined time period that is carefully selected to provide enough speed boost without causing excessive overshoot. After this preliminary high-voltage phase, the voltage transitions to the target value, ensuring the liquid crystal reaches the desired focal power with minimal oscillation and high precision.
Solution Approach 2:
The patent incorporates feedback mechanisms where the actual focal power is monitored and used to adjust subsequent voltage applications. This feedback ensures that even with overdrive voltage applied, the system converges to the precise target focal power by compensating for any overshoot or deviation from the desired state.
3Adaptability or versatility
If uniform voltage is applied across the liquid crystal layer, then the structure is simple, but the phase modulation profile cannot be optimized for different angles of incidence
Solution Approach 1:
The patent divides the liquid crystal layer into multiple regions corresponding to different angles of incidence, and applies different voltage values to each region. This local quality approach allows optimization of phase modulation for each angular zone independently, improving adaptability to various viewing angles while maintaining a relatively simple overall structure through region-based control.
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 solution enables precise and rapid adjustment of focal power and optical center, enhancing the performance of electrically-tunable lenses in adaptive optics, such as spectacles, by optimizing phase modulation profiles and reducing latency in response to changing viewing conditions.
Implementation Method 1
an electro-optical layer, having an effective local index of refraction at any given location within an active area of the electro-optical layer that is determined by a voltage waveform applied across the electro-optical layer at the location
Implementation Method 2
Liquid crystals are the electro-optical material that is most commonly used for this purpose (wherein the applied voltage rotates the molecules, which changes the axis of birefringence and thus changes the effective refractive index)
Data Source
AI summary
An optical device includes an electro-optical layer and conductive electrodes disposed over opposing first and second side of the electro-optical layer. Control circuitry is configured to apply at least first control voltage waveforms and second control voltage waveforms between the conductive electrodes so as to generate respective first and second phase modulation profiles in the electro-optical layer, which cause rays of optical radiation that are incident on the device to converge or diverge with respective first and second focal powers, and to change from the first focal power to the second focal power by concurrently applying overshoot control voltages to each of a plurality of the conductive electrodes for different, respective transition periods, followed by application of the second control voltage waveforms.