Capacitive Touch Sensor Layout for More Buttons With Fewer Pins
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Solution Overview
Problem
Conventional capacitive touch sensing systems require a large number of pins for each additional button, leading to increased space and resource usage, limiting the number of buttons that can be supported, especially in mobile devices with limited space and resources.
Innovation Solution
A capacitive touch sensor system that arranges signal paths from each pin to intersect with others, allowing each pin to support multiple buttons, and uses a method to detect touch inputs by transmitting a signal through one line and analyzing modifications received by other lines, reducing the number of pins needed while enabling efficient fault detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional capacitive touch sensors use one pin per button, then each button can be reliably detected, but the number of pins and board area increases quickly for larger devices
Solution Approach 1:
The patent merges multiple button detection functions into shared pin pairs. Instead of dedicating one pin per button, the system uses pairs of pins that can detect multiple buttons through capacitance measurements, reducing the total pin count and board area required
Solution Approach 2:
Each pin pair is designed to serve multiple buttons universally. The same pin pair can detect capacitance changes from different buttons at different times, allowing pins to perform multiple detection functions rather than being dedicated to a single button
2Adaptability or versatility
If more pins are used to support more buttons, then the number of supported buttons increases, but the space and resource usage increases
Solution Approach 1:
Multiple button detection capabilities are merged into fewer pin pairs. The system combines the detection functions of what would traditionally require separate pins into shared pin pairs that can detect capacitance from multiple buttons through sequential or multiplexed measurements
Solution Approach 2:
The patent transitions from a one-to-one pin-button mapping to a many-to-few relationship by utilizing the capacitance dimension. By measuring capacitance changes between pin pairs, the system can distinguish multiple buttons using the same physical pins, effectively adding a functional dimension beyond simple pin count
3Adaptability or versatility
If signal paths from each pin intersect with others, then fewer pins are needed to support multiple buttons, but the complexity of signal routing increases
Solution Approach 1:
The patent employs asymmetric signal path arrangements where pins are strategically positioned and routed to create intentional intersection patterns. Rather than symmetric grid layouts, the design uses asymmetric routing that allows pin pairs to detect multiple buttons while managing signal interference through careful asymmetrical placement
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 allows for a greater number of buttons to be supported with fewer pins, optimizing space usage and eliminating the need for post-processing to determine touch inputs, while also providing fault detection capabilities.
Implementation Method 1
Each of button 112, button 114, button 116, button 118, button 120, and button 122 are operable to change capacitance when touched by a user
Implementation Method 2
The signal is transferred from the conductor with the higher voltage to the conductor with the lower voltage, where it then travels to a pin set to receive mode
Implementation Method 3
When a user touches one of button 112, button 114, button 116, button 118, button 120, or button 122, the electric field of the two conductors is modified, this modification changes the capacitance between them
Data Source
AI summary
A capacitive touch sensor is disclosed for use with input signal. The capacitive touch sensor includes a number n of input/output lines. Each of the number n of input/output lines is electrically disconnected from every other of the number n of input/output lines. Each of the number n of input/output lines is arranged to cross every other of the number n of input/output lines. Each of a number β of positions includes one of the number n of input/output lines crossing another of the number n of input/output lines.