Multi-State Electrodes for Self-Capacitance Touch Sensors
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Solution Overview
Problem
Self-capacitance sensors face challenges with increased size and cost due to the need for drive rings or dedicated drive electrodes, which also create non-responsive regions and complicate signal routing as the sensor grid grows.
Innovation Solution
The implementation of a system with a plurality of cells, each comprising a transmit and receive electrode, where driving signals are applied in alternating timeslots with inverted signals to eliminate the need for drive rings and improve signal routing by using multi-state electrodes and modulation techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If drive rings or dedicated drive electrodes are used in self-capacitance sensors, then the sensor can detect touch, but the size and cost of the sensor increase
Solution Approach 1:
The patent extracts the drive function from dedicated drive rings or drive electrodes and integrates it into the sensing electrodes themselves. Each sensing electrode is configured to both sense capacitance changes and generate drive signals, eliminating the need for separate drive structures and reducing overall sensor complexity.
Solution Approach 2:
The sensing electrodes are given dual functionality: they serve both as sensing elements for detecting capacitance changes and as drive elements for generating the necessary drive signals. This multi-functionality eliminates the need for separate drive rings or dedicated drive electrodes, reducing sensor size and cost.
2Reliability
If drive rings or dedicated drive electrodes are incorporated within the sensor grid, then the sensor can operate, but regions of the sensor become non-responsive to touch
Solution Approach 1:
By making all sensing electrodes multi-functional (both sensing and driving), the entire sensor grid area becomes responsive to touch. No regions are dedicated solely to driving, thus maximizing the active sensing area while maintaining full sensor operation.
3Measurement precision
If every pixel corresponds to an independent electrode, then image quality is improved, but signal routing becomes difficult as sensor grid size increases
Solution Approach 1:
The patent combines the drive and sense functions into the same electrode structure, allowing sensing electrodes to also serve as drive elements. This integration simplifies signal routing by eliminating the need for separate drive electrode connections, while maintaining independent electrode control for high-resolution imaging.
Solution Approach 2:
The patent employs time-division multiplexing where electrodes are alternately driven and sensed in different time slots. During one time slot, an electrode is driven; during another, it is sensed. This periodic switching allows independent electrode control for high-resolution imaging while simplifying routing through shared signal paths.
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 reduces the complexity and cost of the sensor design, enhances signal-to-noise ratio, and allows for efficient measurement without dedicated drive electrodes, improving the overall performance and accuracy of the sensor.
Implementation Method 1
capacitive touch sensors... configured to sense electrical characteristics of an object
Implementation Method 2
receiving a first measurement signal using the receive electrode of the first cell
Data Source
AI summary
In some embodiments, a method for detecting a portion of a user's body may be provided. The method may be performed by a system comprising a plurality of cells, each cell of the plurality of cells comprising a transmit electrode and a receive electrode. The method may include, in a first timeslot, applying a first driving signal to the transmit electrode of a first cell, and receiving a first measurement signal using the receive electrode of the first cell. The method may further include, in a second timeslot, applying a second driving signal to the transmit electrode of the first cell, and receiving a second measurement signal using the receive electrode of the first cell. The second driving signal may be inverted relative to the first driving signal.