Capacitive Touch Key Structure Without Spring Electrodes
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Solution Overview
Problem
Current capacitive touch-sensing keys have complex structures and poor stability due to the use of springs as sensing electrodes, leading to increased costs and difficulties in installation and quality assurance, as well as susceptibility to detachment under vibration or impact.
Innovation Solution
A touch key structure with a sensing electrode on the circuit board and a conductive medium between the key area and the sensing electrode, allowing for sensitive capacitance detection when a finger approaches or touches the key area, simplifying installation and enhancing stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a spring is used as a sensing electrode in a capacitive touch-sensing key, then the touch sensing function can be achieved, but the structure becomes complex and the installation process becomes complicated
Solution Approach 1:
The patent extracts the spring component from the capacitive touch-sensing key structure and replaces it with a conductive adhesive layer directly mounted on the PCB. This eliminates the complex spring mechanism while maintaining the essential capacitive sensing function through the conductive adhesive layer that forms the sensing electrode.
Solution Approach 2:
The patent replaces the mechanical spring system with an electrical/conductive solution. Instead of using a physical spring to create the sensing electrode, a conductive adhesive layer is applied directly to the PCB, substituting the mechanical structure with a simpler electrical conductor that achieves the same capacitive sensing effect.
2Reliability
If a spring is used as a sensing electrode, then capacitance sensing is enabled, but the manufacturing process becomes complicated and quality assurance becomes difficult
Solution Approach 1:
The spring component is extracted and removed from the manufacturing process. The conductive adhesive layer is applied directly to the PCB in a simple coating process, eliminating the need for spring insertion, positioning, and welding operations that complicate manufacturing and quality control.
Solution Approach 2:
The mechanical spring installation process is replaced with a direct application of conductive adhesive to the PCB. This substitution transforms a complex mechanical assembly process into a simple material deposition process, significantly improving ease of manufacture and quality assurance.
3Reliability
If a spring is used as a sensing electrode, then the touch key function can be implemented, but the cost increases due to additional components and processes
Solution Approach 1:
The spring component is extracted and eliminated from the design. The conductive adhesive layer serves as both the mounting medium and the sensing electrode, removing the need for separate spring components and reducing material costs while simplifying the bill of materials.
Solution Approach 2:
The mounting function and sensing electrode function are merged into a single conductive adhesive layer. This multi-functional approach eliminates the need for separate spring components, reducing part costs and assembly complexity while maintaining the touch key function.
4Reliability
If a spring is used as a sensing electrode, then capacitance detection is possible, but the structure becomes prone to detachment under vibration or impact
Solution Approach 1:
The mechanical spring structure that is prone to detachment is replaced with a conductive adhesive layer that is chemically bonded to the PCB. This substitution eliminates the mechanical connection issues and provides a stable, vibration-resistant sensing electrode that maintains structural integrity under harsh conditions.
Solution Approach 2:
The conductive adhesive acts as an intermediary that provides both mechanical bonding and electrical conductivity. This mediator material securely attaches the sensing electrode to the PCB while maintaining the necessary electrical properties for capacitance detection, solving both structural stability and functional requirements.
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 and reliable touch key structure with improved stability and reduced installation complexity, enhancing the reliability and sensitivity of the capacitive touch-sensing mechanism.
Implementation Method 1
When a user's finger touches or approaches the key area, the finger and the sensing electrode form a capacitance. The capacitance is increased because the conductive medium is provided, and can be sensitively sensed when a finger approaches or touches the key area.
Implementation Method 2
When a finger is close to the area above the electrode, the electric field would be interfered, causing a corresponding change in capacitance.
Data Source
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AI summary
The present disclosure provides a touch key structure and an electrical appliance. The touch key structure includes a touch panel, a circuit board provided behind the touch panel, and a conductive medium. A front side of the touch panel has a key area for a user to touch. The circuit board is provided with a sensing electrode corresponding to the key area. The conductive medium is provided between the key area and the sensing electrode.