Membrane Digital Analog Switch with Dual Threshold Sensing
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Solution Overview
Problem
Existing membrane switches lack the ability to combine digital and analog functionalities in a single button, limiting their application in devices requiring stepless control and proportional pressure sensitivity, such as crane controls and vehicle speed management.
Innovation Solution
The integration of a digital switch with a force-sensing resistor in a membrane design, where the force-sensing resistor is connected in series with a second digital switch, allowing for initial digital signal activation followed by analog control based on increasing pressure, enabling the generation of a variable analog signal corresponding to input pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate digital switches and analog sensors are used, then digital and analog functionalities are achieved, but device complexity and cost increase
Solution Approach 1:
The patent combines a digital switch and an analog sensor into a single integrated membrane switch assembly. The membrane switch includes both a digital switch element and an analog sensor element in one unit, allowing simultaneous digital and analog functionality without requiring separate components. This merging reduces overall device complexity while maintaining functional versatility.
Solution Approach 2:
The membrane switch is designed to perform multiple functions within a single component. It can operate as a digital on/off switch when a threshold force is applied, and simultaneously provide analog force-sensing capability for proportional control. This multi-functionality eliminates the need for separate digital and analog controls, reducing device complexity.
2Adaptability or versatility
If multiple separate switches are used, then digital and analog control are achieved, but manufacturing cost and assembly complexity increase
Solution Approach 1:
The patent integrates the digital switch and analog sensor into a single membrane switch component that can be manufactured as one unit. The membrane structure incorporates both switch types with shared common electrodes, eliminating the need for separate manufacturing and assembly processes for digital and analog controls, thereby simplifying production.
3Measurement precision
If a force-sensing resistor is used for analog control, then pressure sensitivity is achieved, but electromagnetic immunity is reduced
Solution Approach 1:
The patent introduces a signal conditioning circuit as an intermediary between the force-sensing resistor and the control system. This circuit includes filtering and shielding components that protect the analog signal from electromagnetic interference while preserving the pressure-sensing capability. The intermediary elements mediate between the sensitive analog sensor and the electromagnetic environment.
4Volume of moving object
If digital and analog switches are integrated, then compact design is achieved, but signal interference between digital and analog circuits may increase
Solution Approach 1:
The patent divides the membrane switch into distinct functional regions with separate conductive paths for digital and analog signals. The membrane structure includes dedicated signal lines and grounding patterns that segment the electrical pathways, preventing cross-interference between digital and analog circuits while maintaining a compact integrated form factor.
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
This combination reduces the complexity and cost of keypads, enhances reliability, and allows for compact designs with improved electromagnetic immunity, facilitating applications like crane and vehicle speed control by accurately interpreting pressure changes.
Implementation Method 1
a force-sensing resistor adapted to generate an analog switch activation signal when the received pressure on the input button surface is greater than or equal to a specified analog pressure threshold. The analog switch activation signal is variable and corresponds to an analog sensed value of the received pressure on the input button surface.
Data Source
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AI summary
A membrane digital analog switch includes an input button surface adapted to receive an input pressure from a user, and a digital switch positioned below the input button surface to generate a digital switch activation signal when the received pressure on the input button surface is greater than or equal to a specified digital pressure threshold. The membrane digital analog switch also includes an analog switch adapted to generate an analog switch activation signal when the received pressure on the input button surface is greater than or equal to a specified analog pressure threshold. The specified analog pressure threshold is greater than the specified digital pressure threshold, the digital switch activation signal is a binary digital signal, and the analog switch activation signal is variable and corresponds to an analog sensed value of the received pressure on the input button surface.