Switchable Window Fail-Safe Mechanism for Power Failure Visibility
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Solution Overview
Problem
Existing electronically controlled switchable windows fail to meet safety criteria as they revert to low transmissive mode in power failures, such as during a fire, hindering visibility and evacuation due to limited design freedom and increased costs from intrinsic fail-safe mechanisms.
Innovation Solution
An optical device with an active matrix using polymer dispersed liquid crystals, guest-host liquid crystals, or polymer stabilized cholesteric liquid crystals, switchable between high and low transmissive modes, featuring a fail-safe mechanism powered by a battery that maintains the high transmissive mode during grid power interruptions, ensuring safety and design flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If electronically controlled switchable windows use conventional materials (PDLC, suspended particles, etc.), then design freedom and cost are improved, but safety is worsened because the window reverts to low transmissive mode during power failure
Solution Approach 1:
The patent inverts the conventional fail-safe approach by using materials that naturally provide high transmissivity without power, and applying power to switch to low transmissive mode. This reversal allows the use of conventional PDLC or suspended particle materials while achieving safety through the inversion of the default state logic.
Solution Approach 2:
The patent introduces an intermediary electrochromic layer that acts as a mediator between the power supply and the conventional active matrix (PDLC or suspended particles). This electrochromic intermediary provides the fail-safe high transmissive state when power is lost, while allowing the conventional materials to maintain their design freedom and cost advantages.
2Reliability
If switchable windows are designed to be intrinsically fail-safe using vertically aligned liquid crystal mode, then safety during power failure is improved, but design freedom is reduced and cost increases
Solution Approach 1:
The patent segments the window system into distinct functional layers: an electrochromic fail-safe layer and a conventional active matrix layer (PDLC or suspended particles). This segmentation allows each layer to perform its specialized function independently, enabling safety through the electrochromic layer while maintaining design freedom through the conventional materials in the active matrix layer.
Solution Approach 2:
The patent creates a multi-functional system where the electrochromic layer provides fail-safe functionality while the conventional active matrix layer provides design flexibility and cost-effectiveness. This universality allows the combination of different material technologies to achieve multiple objectives simultaneously.
3Ease of manufacture
If switchable windows use materials that revert to low transmissive mode without power, then manufacturing cost and ease of manufacture are improved, but safety during emergencies is worsened
Solution Approach 1:
The patent implements preliminary action by providing an external power supply (battery or UPS) that is pre-configured to activate automatically during power failures. This preliminary preparation ensures that the window maintains its high transmissive state during emergencies without requiring complex intrinsic fail-safe mechanisms in the materials themselves.
Solution Approach 2:
The patent uses an electrochromic layer as an intermediary that can be controlled by the external power supply to maintain high transmissivity during emergencies. This intermediary layer bridges the gap between the conventional materials and the safety requirement, allowing cost-effective manufacturing while improving emergency visibility.
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 fail-safe mechanism ensures the optical device remains in a high transmissive mode during power failures, enhancing safety and design freedom by eliminating the need for specific materials with intrinsic fail-safe mechanisms, allowing for broader application in safety-critical locations.
Implementation Method 1
the active matrix contains polymer dispersed liquid crystals, guest-host liquid crystals suspended particles and/or polymer stabilized cholesteric liquid crystals, the active matrix has a high transmissive mode and a low transmissive mode
Implementation Method 2
polymer dispersed liquid crystals, guest-host liquid crystals suspended particles and/or polymer stabilized cholesteric liquid crystals
Data Source
AI summary
An optical device, having an active matrix, containing polymer dispersed liquid crystals, guest-host liquid crystals, suspended particles and/or polymer stabilized cholesteric liquid crystals, the active high transmissive mode has at least 40% of incoming light transmitted through the optical device and in low transmissive mode less than 40% of incoming light transmitted through the optical device, the active matrix is switchable between high transmissive mode and low transmissive mode. The optical device containing a fail-safe mechanism, which is capable to switch the active matrix from a low transmissive mode in a high transmissive mode without the power of an applied grid.The optical device has a fail-safe mechanism comprising at least one battery and a controller.