Mutual Capacitance Touch Sensing with Two-Level Noise-Resistant Coding
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Solution Overview
Problem
Existing touch sensing technologies face challenges in effectively detecting position-based attributes of objects amidst noise interference, particularly from display screens, power sources, and wireless frequencies, which affects accuracy and efficiency.
Innovation Solution
The implementation of a touch sensing method and device that utilizes spread spectrum coding and orthogonal coding for mutual capacitance touch sensors, allowing for robust noise resistance and simultaneous driving of multiple touch sensors to enhance sensitivity and reduce sensing time. This involves coding base signals with spread spectrum codes and orthogonal codes to generate driving signals, converting response signals into digital data, and decoding them to determine object proximity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional touch sensing methods are used, then the system is simple to implement, but noise from display screens, power sources, and wireless frequencies degrades measurement precision
Solution Approach 1:
The patent applies spread spectrum coding to modulate the touch sensing signal across a wide frequency range, transforming the concentrated noise problem into a distributed signal that can be distinguished from narrowband interference. Orthogonal coding is used to multiplex multiple transmission electrodes, changing the temporal and spectral parameters of the driving signals to enable noise-resistant detection
Solution Approach 2:
The patent introduces coded driving signals as an intermediary between the transmission electrodes and the touch sensing measurement. By encoding the drive signals with spread spectrum and orthogonal codes, the system creates a mediated measurement process that filters out noise through correlation detection, improving measurement precision in noisy environments
2Productivity
If multiple touch sensors are driven simultaneously, then productivity increases and sensing time is reduced, but signal separation becomes more difficult
Solution Approach 1:
The patent segments the touch sensing measurement into multiple orthogonal channels by assigning different orthogonal codes to different transmission electrodes. This segmentation allows simultaneous driving of multiple sensors while maintaining the ability to separate their responses through correlation detection with the respective orthogonal codes
Solution Approach 2:
The patent uses periodic orthogonal coding sequences to drive multiple transmission electrodes in a time-multiplexed manner. The orthogonal codes provide periodic signal structures that enable clear separation of simultaneous measurements through correlation processing, increasing productivity without excessive complexity
3Reliability
If spread spectrum coding is applied, then noise resistance improves, but device complexity increases
Solution Approach 1:
The patent uses identical orthogonal codes for both transmitting drive signals and receiving response signals. This copying approach simplifies the device architecture by using the same code sequences for encoding and decoding, reducing device complexity while maintaining reliable noise-resistant operation through correlation detection
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
The solution provides robust noise resistance and enhanced touch sensitivity by enabling simultaneous operation of multiple touch sensors, thereby reducing sensing time and improving signal-to-noise ratio.
Implementation Method 1
mutual capacitance touch sensors formed by multiple transmission electrodes TXE and a reception electrode RXE
Data Source
AI summary
The embodiment applies a two-level coding/decoding technology using a spread spectrum code and an orthogonal code, whereby touch sensing can be robust against noise, a touch sensing time can be reduced, and touch sensitivity can be enhanced.