Switchable Device Variable Opacity Glazing
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Solution Overview
Problem
Conventional vehicle windscreen shade bands, typically made of tinted polyvinyl butyral (PVB), are fixed in position and cannot adjust to changing sun positions, limiting optimal opacity and transmission, and require separate capacitor networks for SPD films, which complicates power transmission.
Innovation Solution
A switchable device with two or more switchable regions, each comprising an electrically actuated variable opacity layer between electrodes, connected in series or parallel, using a low-frequency power supply to change opacity, allowing for adjustable opacity without external capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a high frequency power supply is used to switch SPD films, then the opacity of the SPD film can be changed, but the series impedance increases due to the inductance of transmission lines, making power transmission difficult
Solution Approach 1:
The patent changes the operating frequency parameter from high frequency to low frequency (e.g., 50/60 Hz mains frequency), which fundamentally alters the electrical characteristics of the transmission lines. At low frequencies, the inductive reactance (XL = 2πfL) becomes negligible, eliminating the series impedance problem that plagues high frequency SPD switching. This parameter change enables straightforward power transmission without complex impedance matching or specialized high frequency power supplies.
2Adaptability or versatility
If separate capacitor networks are used to power individual SPD films, then each SPD film can be switched independently, but the device complexity increases
Solution Approach 1:
The patent merges multiple SPD films into a single electrical circuit configuration where they are connected in series between two common electrodes. This eliminates the need for separate capacitor networks for each film. The series connection allows all films to be switched simultaneously by a single voltage application, reducing component count and simplifying the power distribution architecture while maintaining the ability to control opacity across multiple films.
Solution Approach 2:
The patent creates a universal electrode structure where two common electrodes serve multiple functions: they act as electrodes for all SPD films simultaneously, eliminate the need for individual capacitor networks, and provide a simplified power distribution interface. This multi-functional design reduces the overall system complexity while maintaining the capability to switch multiple films.
3Adaptability or versatility
If a fixed tinted region of PVB is used in the windscreen, then the windscreen can be manufactured with a shade band, but the position of the shade band is fixed and cannot be adjusted to changing sun positions
Solution Approach 1:
The patent replaces the static, fixed-position PVB tinted region with dynamic SPD films that can change their optical properties electrically. The SPD films are positioned in the same location as the traditional shade band but can be switched between transparent and opaque states on demand. This dynamic capability allows the shade band to adapt to changing sun positions throughout the day without requiring physical repositioning or complex mechanical adjustment mechanisms, maintaining manufacturing simplicity while achieving adaptability.
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
Enables adjustable opacity in vehicle glazing, improving light transmission and accommodating changing sun positions with reduced power transmission complexity, using a single pair of electrical connector regions.
Implementation Method 1
the switchable regions may be electrically connected in series and/or in parallel as if each switchable region was a capacitor
Implementation Method 2
each switchable region comprising an electrically actuated variable opacity layer between a first electrode and a second electrode
Data Source
AI summary
A switchable device for changing the opacity of at least a portion of a glazing is described. The switchable device comprises at least two (a first and a second) switchable regions in electrical communication with at least two (a first and a second) electrical connector regions. Each switchable region comprises an electrically actuated variable opacity layer between a first electrode and a second electrode, the first switchable region being arranged relative to the second switchable region such that upon connecting the first and second electrical connector regions to a suitable power supply, the opacity of the first and second switchable region changes such that at least two (a first and a second) portions of the switchable device have a change of opacity, the first portion of the switchable device having a different opacity to the second portion of the switchable device.