Multi-State Cholesteric Liquid Crystal Optical Control
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Solution Overview
Problem
Existing light shutters and optical filters, such as electrochromic, suspended particle devices, and thermochromic materials, face limitations in transmittance, response time, and energy requirements, failing to effectively control light and heat in a versatile and efficient manner for protecting sensors and displays.
Innovation Solution
A single layer multi-state cholesteric liquid crystal device with optically transparent substrates and a liquid crystal that can switch between broadband reflection, tunable narrow band reflection, light scattering, and transparency based on applied voltage, allowing for flexible optical states for infrared, visible, and ultraviolet light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If electrochromic materials are used to control light transmission, then opacity control is achieved, but transmittance is limited to 38% in clear state and visible light attenuation reaches 55%
Solution Approach 1:
The patent applies parameter changes by utilizing voltage-controlled optical transitions in cholesteric liquid crystal devices. The device transitions between different optical states (transparent, reflective, scattering) by changing the applied voltage parameter, achieving broadband reflection and high transmittance without the limitations of electrochromic materials. This enables the system to achieve greater than 90% transmittance in clear state while providing multiple adjustable optical states.
2Illumination intensity
If suspended particle devices are used for light control, then dimming capability is provided, but clear state transmittance is limited to 51% and constant electrical current is required
Solution Approach 1:
The patent applies periodic action through pulse-width modulation (PWM) driving schemes. Instead of requiring constant electrical current, the device uses periodic voltage pulses to maintain the desired optical state. The liquid crystal device is switched between states using pulsed signals, reducing continuous energy consumption while maintaining the ability to control light transmission at greater than 90% in clear state.
3Illumination intensity
If thermochromic materials are used for light control, then automatic temperature response is achieved, but clear state transmittance is only around 40%
Solution Approach 1:
The patent applies dynamics by creating a dynamically controllable optical system using voltage-adjustable cholesteric liquid crystal devices. Unlike static thermochromic materials, the device allows real-time dynamic control of optical properties through voltage adjustment. The system can be manually controlled to achieve greater than 90% transmittance while maintaining the capability for automated control through integration with sensors and control circuits.
4Reliability
If prior-art optical filters and shutters are used to protect sensors, then sensor protection is achieved, but response time is slow and transmittance control is limited
Solution Approach 1:
The patent applies mechanics substitution by replacing mechanical shutters and complex optical filter systems with an electrically-controlled cholesteric liquid crystal device. This substitution eliminates moving parts and mechanical complexity, achieving rapid response times while providing comprehensive sensor protection. The device can quickly transition between transparent and protective states, offering both reliability and speed.
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 rapid and efficient control over light and heat transmission, offering high transmittance and adjustable opacity without continuous electrical current, addressing the limitations of prior technologies.
Implementation Method 1
a liquid crystal having portions adapted for producing a plurality of optical states, said liquid crystal being arranged between the two optically transparent substrates
Implementation Method 2
changing the optical states of the liquid crystal ranging from one state to any combination of broadband reflection, tunable narrow band reflection, light scattering, and transparency in accordance with a voltage applied to the device
Implementation Method 3
an optical sensor for changing optical states of respective portions of said liquid crystal to produce a range of respective optical states
Data Source
AI summary
A sensing device may include a cholesteric crystal device including two optically transparent substrates; a liquid crystal having portions adapted for producing a plurality of optical states, said liquid crystal being arranged between the two optically transparent substrates; an optical sensor for changing optical states of respective portions of said liquid crystal to produce a range of respective optical states including all optical states produced by said liquid crystal ranging from one state to any combination of broadband reflection, tunable narrow band reflection, light scattering, and transparency in accordance with an amount of voltage applied across said cholesteric crystal device for changing optical states.