Normally Closed Switch With Flexible Conductive Blade
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Solution Overview
Problem
Current technologies for manufacturing flexible keyboards with normally closed electrical contacts are complex, expensive, and unsuitable for portable communication devices, as they require voluminous buttons or electronic management, which are costly and impractical.
Innovation Solution
A method for manufacturing a flexible keyboard with a normally closed electrical contact using a recto-verso printed circuit with an insertion slot for a flexible conductive blade, featuring a fulcrum for exerting a breaking force, allowing the contact to be easily integrated into thin keyboards without additional constraints, maintaining low thickness and competitive manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional normally closed switches are integrated into flexible keyboards, then reliable electrical contact is achieved, but device complexity and manufacturing cost increase significantly
Solution Approach 1:
The switch is segmented into distinct functional components: a flexible printed circuit board with contact pads, a movable conductive element with contact surfaces, and a housing structure. This segmentation allows each component to be optimized independently and assembled into a compact configuration suitable for flexible keyboards.
Solution Approach 2:
The conductive element is nested within the housing structure, with the flexible printed circuit board integrated into the same assembly. The contact surfaces are positioned within the housing to engage with corresponding contact pads, creating a compact nested arrangement that reduces overall device complexity.
2Reliability
If voluminous buttons are integrated to achieve normally closed contact, then reliable electrical contact is achieved, but keyboard thickness increases
Solution Approach 1:
The switch design transitions from a voluminous three-dimensional button structure to a planar configuration where the flexible printed circuit board provides the necessary movement dimension. The conductive element moves within the plane of the keyboard rather than requiring significant thickness, achieving normally closed contact without increasing keyboard thickness.
Solution Approach 2:
The flexible printed circuit board serves as both the structural support and the movable contact element. This thin film structure replaces traditional voluminous buttons, providing the necessary elasticity and contact pressure while maintaining a thin profile suitable for modern flexible keyboards.
3Ease of operation
If complex electronic management is implemented for normally closed contacts, then contact control is achieved, but manufacturing cost increases
Solution Approach 1:
The switch is designed as a self-contained mechanical component that automatically maintains normally closed contact through the elastic properties of the flexible printed circuit board. The conductive element naturally engages with the contact pads without requiring external electronic control systems, eliminating the need for complex electronic management and reducing manufacturing costs.
Solution Approach 2:
The design replaces complex electronic management systems with a simple mechanical solution based on elastic deformation of the flexible printed circuit board. The mechanical elasticity provides the necessary contact pressure and reset function, substituting for expensive electronic control circuitry.
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 a simple, economical, and compact structure for flexible keyboards that can operate reliably for hundreds of thousands of cycles, is resistant to vibrations and shocks, and easy to implement, while maintaining the advantages of flexible membrane technology.
Implementation Method 1
a flexible conductive blade forming a normally closed electrical contact between the recto contact pad and the verso contact pad, this flexible blade comprising a fulcrum allowing the exertion of a breaking force on the normally closed electrical contact
Data Source
Figure 1a~1d
Figure 2~4
Figure 5~8
AI summary
The switch (10) comprises a printed circuit (12), of generally plane shape, and comprising a first face bearing a first contact pad, a second face (12B), opposite the first, bearing a second contact pad (18), and a through-orifice (14) allowing access between the first face (12A) and the second face (12B). The switch (10) also includes a conductor (20), comprising a first part (22), which cooperates with the first contact pad (16), and a second part (24), which extends between a first end (24A), fixed to the first part (22), and a free second end (24B), passing through the orifice (14). The second part (24) is elastically deformable between a rest position, in which its second end (24B) cooperates with the second contact pad (18), and a stressed position, in which its second end (24B) is moved away from the second contact pad (18).