3D Membrane Keypad Manufacturing via UV Casting
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Solution Overview
Problem
Existing methods for manufacturing three-dimensional flexible switch or user interface surfaces are limited to flat geometries, lacking the ability to create closed, three-dimensionally shaped structures with high-quality molded key geometries and sufficient thickness for functional actuation.
Innovation Solution
A method involving a compression mold with a depression and a counterstamp to form a three-dimensionally structured surface layer using a transparent casting compound, cured with UV radiation, allowing for a self-supporting, flexible surface with front surface curvature and rear depression, accommodating additional functional elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If membrane keyboards with embossing or coating are used, then a closed surface is achieved, but the surface is limited to flat basic geometry
Solution Approach 1:
The patent changes the physical state of the casting compound from liquid (uncured) to solid (cured) to enable three-dimensional shaping. By using a casting compound that transitions from fluid to rigid state, the invention achieves complex surface geometries with varying curvatures that were impossible with traditional flat membrane keyboards
Solution Approach 2:
The patent uses a composite structure combining a flexible substrate with a cured casting compound surface layer. This composite approach allows the base membrane to remain flexible while the surface layer provides the desired three-dimensional shape and structural integrity
2Shape
If thermoformed films are used, then three-dimensional shape is achieved, but bending radii are restricted and sharp edges are not possible
Solution Approach 1:
The patent uses a casting process where liquid compound is poured into a mold and then cured, allowing for sharp edges and precise geometric features that cannot be achieved through thermal forming. The mold defines the exact geometry including sharp edges, and the curing process locks this geometry in place
Solution Approach 2:
The patent replaces the mechanical thermoforming process with a casting and curing process. Instead of heating and mechanically forming the material, the invention uses liquid casting followed by chemical or UV curing, which eliminates the bending radius restrictions inherent in thermoforming
3Ease of operation
If plastic buttons in housing are used, then functional actuation is achieved, but the structure is thick and bulky
Solution Approach 1:
The patent uses a flexible membrane keyboard with a thin cured surface layer instead of thick rigid plastic buttons. The flexible substrate allows for thin construction while maintaining functional actuation capability through the cured casting compound surface that provides the necessary structural properties
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 the creation of a closed, three-dimensional surface layer with varying thickness, allowing for sharp-edged keys and integrated functional elements, enhancing tactile feedback and aesthetic appeal while reducing component complexity.
Implementation Method 1
Energy is then introduced into the potting compound so that the potting compound hardens... The energy is introduced in the form of UV radiation, typically at least partial crosslinking and/or polymerisation of the casting compound takes place during the curing process.
Data Source
Figure 1a~1b
Figure 2a~2b
Figure 3
AI summary
The invention relates to a method for producing a flexible, three-dimensional coating structure (2,4,12) with a front surface curvature (23) and a rear recess (24) for a flexible switch or a flexible user interface.The process is essentially characterized by the following process steps: an uncured transparent casting compound (14) is placed into a press mold (13) with a recess (15) forming a surface bulge (21); a counter-punch (17) penetrating at least partially into the recess (15) is inserted, so that the casting compound (14) spreads in the gap between the surface bulge (21) of the press mold (13) and the surface of the counter-punch (17) and fills this gap; energy is introduced into the casting compound (14) so that the casting compound (14) cures to form a substantially self-supporting, flexible, transparent surface layer (4) with a front surface bulge (23) and a rear recess (24).