Infrared-Transparent Opaque Cover Coating to Reduce Display Brittleness
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Solution Overview
Problem
Challenging to provide a coating that imparts desired optical characteristics to electronic devices over a range of different wavelengths without making the device excessively brittle and prone to damage.
Innovation Solution
A coating stack is applied to the display cover layer of electronic devices, comprising infrared transparent and visibly opaque ink layers, optionally with an infrared antireflective coating, to allow infrared light transmission while hiding infrared sensors and emitters and reducing brittleness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a multi-layer physical vapor deposition (PVD) coating is deposited directly onto the display cover layer, then the coating imparts desired optical characteristics over a range of wavelengths, but the display cover layer becomes excessively brittle and prone to damage
Solution Approach 1:
The coating system is divided into separate functional layers: an infrared-transparent visibly-opaque (ITVO) ink layer applied first, followed by an infrared antireflective coating applied second. This segmentation allows each layer to be optimized for its specific function without compromising the substrate's mechanical properties, as the ITVO layer provides optical functionality while the antireflective layer enhances infrared transmission without inducing brittleness in the display cover layer
Solution Approach 2:
The ITVO ink layer serves as an intermediary between the display cover layer and the infrared antireflective coating. This intermediate layer allows the antireflective coating to be applied without directly bonding to the display cover layer, thereby preventing the transmission of mechanical stress that would cause brittleness, while still enabling the antireflective coating to perform its optical function
2Reliability
If the infrared sensor and emitter are visible through the display cover layer, then the optical properties are maintained, but the aesthetic appearance and user experience are degraded
Solution Approach 1:
The ITVO ink layer is applied specifically to regions where infrared sensors and emitters are located, creating a locally selective optical property. This layer is invisible to infrared light (allowing sensor operation) but opaque to visible light (hiding the components from view), thus providing different optical qualities in different wavelength ranges at the same location
Solution Approach 2:
The ITVO ink layer exhibits wavelength-dependent optical properties: it appears opaque in the visible spectrum (hiding infrared components) while remaining transparent in the infrared spectrum (allowing sensor operation). This selective transparency/opacity based on wavelength effectively 'changes color' depending on the light source used to view it
3Reliability
If an infrared antireflective coating is applied directly to the display cover layer, then infrared light transmission is enhanced, but the coating increases device brittleness and complexity
Solution Approach 1:
The coating system is segmented into two distinct layers with the ITVO ink layer applied first and the infrared antireflective coating applied second. This segmentation allows the antireflective coating to be applied without directly bonding to the display cover layer, preventing the transmission of mechanical stress that would cause brittleness while maintaining infrared transmission enhancement
Solution Approach 2:
The ITVO ink layer acts as an intermediary substrate for the infrared antireflective coating, allowing the coating to be applied without directly contacting and potentially weakening the display cover layer. This intermediate layer absorbs the mechanical stress of coating application while preserving the structural integrity of the display cover layer
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 coating stack enhances optical properties for infrared light transmission while minimizing device brittleness and reducing cross-talk, maintaining structural integrity.
Implementation Method 1
one or more infrared transparent and visibly opaque ink layers overlapping the infrared sensor and the infrared emitter in the inactive island
Implementation Method 2
The infrared antireflective coating may be formed from a multi-layer thin-film interference filter
Data Source
AI summary
An electronic device may be provided with a visible and infrared transparent cover layer. The electronic device may include infrared devices that operate on infrared light passing through the cover layer. One or more infrared transparent and visibly opaque ink layers may be disposed on the cover layer overlapping the infrared devices. An optional infrared antireflective coating may be layered onto the infrared transparent and visibly opaque ink layer(s). The ink layer(s) may pass the infrared light while blocking visible light to help hide the infrared devices from view. Layering the ink layer(s) onto the cover layer may cause the cover layer to be less brittle than when a physical vapor deposition (PVD) coating is layered directly onto the cover layer.