Tapered Capsense Touchpad Interleaved Traces Pin Reduction
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Solution Overview
Problem
Conventional touchpads require a large number of pins to detect position and gestures, which can complicate their design and increase the number of components needed, making them less efficient and more cumbersome for portable devices.
Innovation Solution
A touchpad system that integrates a processing device with a capacitance sensor and a relaxation oscillator, using a multi-dimensional sensor array with interleaved conductive traces to detect changes in capacitance, reducing the number of pins required by using a programmable interconnect and logic (PIL) to connect GPIO ports to a digital block array, allowing for efficient detection of user inputs and gestures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional touchpad structures with multiple conductive trace layers are used, then position detection capability is achieved, but the number of pins required increases significantly
Solution Approach 1:
The patent combines row and column conductive traces into a single layer with interleaved patterns. Instead of using separate layers for rows and columns that require independent pin connections, the interleaved single-layer design allows both row and column signals to be detected through shared trace structures, reducing the total pin count while maintaining two-dimensional position detection capability.
Solution Approach 2:
The conductive traces in the interleaved pattern serve multiple functions simultaneously. Each trace acts as both a row trace and a column trace at different positions, enabling the same physical structure to detect signals in both horizontal and vertical directions without requiring dedicated traces and pins for each direction.
2Measurement precision
If multiple layers of conductive traces are used for multi-dimensional sensing, then gesture detection accuracy improves, but device thickness and manufacturing complexity increase
Solution Approach 1:
The patent segments the sensing function into interleaved trace patterns within a single layer rather than using multiple stacked layers. This segmentation approach distributes the row and column sensing functions throughout the same plane, eliminating the need for precise layer-to-layer alignment while maintaining the ability to detect multi-dimensional gestures through the interleaved pattern geometry.
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 solution reduces the number of pins needed, simplifies the design, and enhances the efficiency of touchpad systems, enabling more compact and portable devices while maintaining accurate gesture detection and position sensing.
Implementation Method 1
the capacitance between the conductive lines and ground varies and can be detected
Data Source
AI summary
A touchpad has interleaved conductive traces across a touchpad surface. Each conductive trace has a first end and a second end. The width of the first end is larger than the width of the second end. The interleaved conductive traces have a first group of conductive traces alternated with a second group of conductive traces.