Capacitive Touch Button Layout With Two-Pin Multi-Button Detection
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Solution Overview
Problem
Conventional touch-sensor button configurations require a one-to-one pin configuration, leading to increased pin count and scan time, as well as memory requirements, making it inefficient to add more buttons without significant hardware changes.
Innovation Solution
The use of two sensing areas with electrically isolated portions, coupled to only two pins of a processing device, allows for the recognition of multiple button operations using a capacitive switch relaxation oscillator, reducing the need for additional pins and memory by interleaving sub-bars to form multiple sensor elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a one-to-one configuration of pins to touch-sensor buttons is used, then each button can be detected independently, but the pin count increases and scan time increases
Solution Approach 1:
Multiple sensor elements are electrically connected in parallel to share common pins, merging multiple detection functions into a single pin connection. This allows three or more buttons to be detected using only two pins, reducing device complexity while maintaining independent button detection capability through software processing of capacitance variations.
Solution Approach 2:
The sensing device uses two sensing areas that can detect multiple different button operations (first button operation, second button operation, third button operation) simultaneously. The same two pins serve multiple detection functions by measuring capacitance variations across different sensor element combinations, making the pin structure universal for multiple button functions.
2Adaptability or versatility
If more touch-sensor buttons are added, then functionality increases, but memory requirements increase
Solution Approach 1:
Multiple sensor elements are electrically connected in parallel to share common pins, merging multiple detection functions into a single pin connection. This allows three or more buttons to be detected using only two pins, reducing device complexity while maintaining independent button detection capability through software processing of capacitance variations.
Solution Approach 2:
The sensing device uses two sensing areas that can detect multiple different button operations (first button operation, second button operation, third button operation) simultaneously. The same two pins serve multiple detection functions by measuring capacitance variations across different sensor element combinations, making the pin structure universal for multiple button functions.
3Reliability
If a one-to-one configuration of pins to touch-sensor buttons is used, then each button can be detected independently, but scan time increases
Solution Approach 1:
Multiple sensor elements are electrically connected in parallel to share common pins, merging multiple detection functions into a single pin connection. This allows three or more buttons to be detected using only two pins, reducing device complexity while maintaining independent button detection capability through software processing of capacitance variations.
Solution Approach 2:
The sensing device uses two sensing areas that can detect multiple different button operations (first button operation, second button operation, third button operation) simultaneously. The same two pins serve multiple detection functions by measuring capacitance variations across different sensor element combinations, making the pin structure universal for multiple button functions.
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 approach enables the expansion of touch-sensor buttons without increasing scan time or memory requirements, allowing for more buttons to be implemented with reduced complexity and resource usage, while maintaining efficient capacitance measurement.
Implementation Method 1
the processing device 110 may include capacitance sensors 104-106, which are coupled to buttons 101-103, respectively. The capacitance sensors of the processing device are coupled to the touch-sensor buttons in a one-to-one configuration. Accordingly, the processing device 110 scans the touch-sensor buttons 101-103 using the capacitance sensors 104-106, and measures the capacitance on the touch-sensor buttons 101-103.
Data Source
AI summary
A method and apparatus to detect a conductive object at a location determines a capacitance variation of a first sensor element and a capacitance variation of a second sensor element. The method and apparatus detects a touch at a first location if the capacitance variation of the first sensor element is greater than a reference value and the capacitance variation of the second sensor element is not greater than the reference value. The method and apparatus detects the touch at a second location if the capacitance variation of the first sensor element is not greater than the reference value and the capacitance variation of the second sensor element is greater than the reference value. The method and apparatus detects the touch at a third location if the capacitance variation of the first sensor element and the capacitance variation of the second sensor element are both greater than the reference value.