Backlit Touch Interface Using Transparent Circuit Film on Curved Surfaces
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Solution Overview
Problem
Traditional user interfaces for devices rely on costly substrates like PCBs and FPCs, which limit backlight quality and cannot accommodate curved surfaces or in-molded designs, leading to suboptimal user experience.
Innovation Solution
A backlit user interface device featuring a transparent lens, a fold-over transparent circuit film with LEDs and spacers, silver conductors for capacitive touch, and a layer of transparent pressure-sensitive adhesive, allowing for improved backlighting and capacitive sensing on curved surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If traditional substrates like PCBs or FPCs are used, then structural support is provided, but light cannot transfer from one side to the other and higher cost is incurred
Solution Approach 1:
The patent removes the traditional PCB or FPC substrate entirely and extracts only the essential functions needed: structural support, electrical connectivity, and light transmission. This is achieved by separating the circuit functionality (on a thin flexible circuit) from the substrate functionality (provided by the lens itself), eliminating the need for expensive molded light pipes and complex PCB structures.
Solution Approach 2:
The lens is given multiple functions: it serves as both the optical element for backlight diffusion and as the structural substrate that provides mechanical support and electrical connectivity pathways. The transparent circuit film similarly serves dual purposes as both a structural element and a circuit carrier, eliminating the need for separate dedicated substrates.
2Ease of manufacture
If PCBs and FPCs are used, then electrical connectivity is achieved, but they require molded light pipes and light guides which increase complexity and cost
Solution Approach 1:
The patent merges multiple previously separate components into integrated structures. The lens and substrate are combined into a single multi-functional element. The circuit film integrates structural support with electrical connectivity. The adhesive layer simultaneously provides bonding and structural alignment. This consolidation reduces the total component count and simplifies the manufacturing process.
3Adaptability or versatility
If traditional rigid substrates are used, then structural stability is provided, but curved surfaces and in-molded designs cannot be accommodated
Solution Approach 1:
The patent employs flexible thin films for both the circuit carrier and the adhesive layer. The circuit film can be bent and conform to curved surfaces while maintaining electrical connectivity. The pressure-sensitive adhesive film provides flexible bonding that accommodates non-planar geometries. This flexibility enables the user interface to be integrated into curved or irregularly shaped device surfaces.
4Illumination intensity
If transparent materials are used for backlighting, then light transmission is improved, but capacitive touch sensing becomes more difficult
Solution Approach 1:
The patent applies different material properties to different regions of the user interface. The lens uses highly transparent material for optimal light diffusion and visibility. The circuit film uses transparent or translucent material in regions where backlight transmission is needed, while maintaining capacitive sensing functionality. The adhesive layer is positioned and configured to provide both optical clarity and electrical isolation where needed, allowing simultaneous optimization of both backlighting and touch sensing in different locations.
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 enhanced backlighting and capacitive touch functionality on curved surfaces, reducing costs and improving user interface quality compared to traditional designs.
Implementation Method 1
at least one light emitting diode (LED)
Implementation Method 2
a layer of transparent pressure-sensitive adhesive that secures the bottom surface of the lens to the top surface of the transparent circuit film
Implementation Method 3
at least one silver conductor
Data Source
AI summary
An user interface device includes a lens with a top surface and a bottom surface, where the bottom surface includes at least one graphic that is visible through the top surface of the lens. The user interface device further includes a transparent circuit film with a top surface and a bottom surface, at least one light emitting diode (LED), at least one silver conductor, and a layer of transparent pressure-sensitive adhesive that secures the bottom surface of the lens to the top surface of the transparent circuit film.