Touch Sensing System With Differential Amplifier Inversion
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Solution Overview
Problem
Existing touch sensing systems face challenges in maintaining a high signal-to-noise ratio, particularly in edge channels, and require increased processing time and complexity when scaling touch screens, leading to reduced accuracy and increased data processing time.
Innovation Solution
A touch sensing system that incorporates a touch sensing integrated circuit with differential amplifiers and a multiplexer to switch input signals between forward and reverse sensing modes, improving signal-to-noise ratio by selectively connecting adjacent sensing lines and removing noisy channels, thereby enhancing touch input detection and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a dummy signal is applied to the non-inverting input terminal of the differential amplifier connected to the first or last Rx channel, then the number of sensor signals can be increased to N, but the signal-to-noise ratio of the edge channels is reduced
Solution Approach 1:
The patent applies reverse sensing by inverting the connection of sensing lines to differential amplifiers. Specifically, it connects the first sensing line to the non-inverting input terminal and the second sensing line to the inverting input terminal of the first differential amplifier, and similarly inverts connections for the last differential amplifier. This inversion allows edge channels to achieve proper differential amplification without dummy signals, resolving the signal-to-noise ratio degradation problem while maintaining N sensor signals.
Solution Approach 2:
The patent changes the connection parameters of sensing lines to differential amplifiers between forward sensing mode and reverse sensing mode. By switching the which sensing line connects to which input terminal based on sensing mode, the system achieves optimal signal-to-noise ratio for edge channels without requiring dummy signals, thus maintaining both quantity and quality of sensor signals.
2Area of stationary object
If multiple ICs are connected to large-sized touch screens with increased number of Tx and Rx channels, then the touch screen size and resolution can be increased, but the data processing time and complexity increase
Solution Approach 1:
The patent merges forward sensing results and reverse sensing results from multiple ICs processing adjacent sensing lines. By combining results from IC#1 and IC#2 through the multiplexer and processing logic, the system achieves complete touch screen coverage without requiring each IC to independently process all channels, reducing overall data processing time and complexity for large-sized touch screens.
Solution Approach 2:
The patent segments the touch screen sensing into multiple ICs, each handling specific sensing lines. By dividing the sensing task across multiple ICs with each processing a subset of adjacent sensing lines in both forward and reverse modes, the system manages large touch screen data more efficiently, reducing the processing burden on individual ICs and overall system complexity.
3Measurement precision
If differential amplifiers amplify the difference between sensor signals from adjacent Rx lines, then the signal-to-noise ratio is improved, but the processing complexity increases
Solution Approach 1:
The patent implements periodic switching between forward sensing mode and reverse sensing mode. The multiplexer alternates connecting sensing lines to differential amplifiers in different configurations, allowing the system to achieve high signal-to-noise ratio through differential amplification while managing processing complexity through structured periodic operation rather than continuous complex processing.
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 system effectively improves the signal-to-noise ratio across all receiving channels, reduces processing complexity, and maintains accuracy even with large-sized touch screens by selectively handling noisy channels, thus enhancing touch input detection and data processing efficiency.
Implementation Method 1
each of the plurality of differential amplifiers configured to amplify a difference between touch sensor signals received through adjacent sensing lines
Implementation Method 2
a multiplexer configured to connect the adjacent sensing lines to input terminals of each differential amplifier in a forward sensing mode and switch the adjacent sensing lines connected to the input terminals of each differential amplifier in a reverse sensing mode
Data Source
AI summary
A touch sensing system includes a plurality of touch sensors, sensing lines connected to the touch sensors, a touch sensing integrated circuit (IC) sensing a touch input using signals received through a plurality of receiving channels, a plurality of differential amplifiers which are formed between the sensing lines and the receiving channels of the touch sensing IC and amplify a difference between touch sensor signals received through adjacent sensing lines, and a multiplexer which connects the adjacent sensing lines to input terminals of each differential amplifier in a forward sensing mode and switches the adjacent sensing lines connected to the input terminals of each differential amplifier in a reverse sensing mode.