Touch Sensing System Boundary Noise Reduction via Switched Differential Amplification
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Solution Overview
Problem
The signal-to-noise ratio (SNR) is reduced at the boundary between touch sensing integrated circuits (ICs) in large-sized touch screens, making it difficult to accurately detect touch inputs in the middle portion of the screen, as existing methods increase data processing time and reduce accuracy.
Innovation Solution
A touch sensing system that includes a switch connecting the closest sensing line of the second sensing area to the Nth differential amplifier of the first touch sensing IC, improving the SNR by amplifying the difference between adjacent Rx lines and reducing noise components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple touch sensing ICs are used to drive large-sized touch screens, then the touch screen can be divided into multiple sensing areas, but the signal-to-noise ratio is reduced at the boundary between ICs
Solution Approach 1:
The patent introduces an intermediary switching mechanism that connects the sensing lines from multiple ICs to a unified differential amplifier. This mediator (switch) allows the system to dynamically route signals from different ICs to the same processing circuit, enabling noise cancellation across IC boundaries without requiring separate processing paths for each IC.
Solution Approach 2:
The patent merges the signal processing paths of multiple ICs by directing all sensing lines to a common differential amplifier. Instead of having separate amplifiers for each IC, the system combines all inputs into a single amplification stage, allowing the differential amplifier to process signals from multiple sources simultaneously and eliminate boundary noise issues.
2Power
If differential amplifiers are connected to all Rx channels, then signal components are increased, but noise components are also amplified at IC boundaries
Solution Approach 1:
The patent introduces dynamic control of the switching mechanism based on signal detection. The system dynamically adjusts which sensing lines are connected to the differential amplifier based on the presence and location of touch inputs, allowing the system to optimize signal processing in real-time and avoid amplifying noise when no touch occurs in boundary regions.
Solution Approach 2:
The patent applies different processing strategies to different regions of the touch screen. Boundary regions receive enhanced signal processing through the switching mechanism that directs signals to the differential amplifier, while non-boundary regions use standard processing. This localized quality adjustment optimizes performance for the specific problem areas (boundaries) without affecting overall system performance.
3Ease of operation
If dummy signals are applied to non-inverting input terminals, then differential amplifiers can operate, but signal-to-noise ratio is reduced due to amplified noise components
Solution Approach 1:
The switching mechanism acts as an intermediary that selectively connects sensing lines to the differential amplifier's inverting input terminal based on signal detection. This mediator allows the system to determine when and where to apply the dummy signal strategy, enabling differential amplifier operation only when necessary and avoiding unnecessary noise amplification in regions where it would be harmful.
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
Enhances the signal-to-noise ratio at the boundary between touch sensing ICs, allowing for more accurate touch input detection without increasing data processing time or reducing accuracy.
Implementation Method 1
Each of the differential amplifiers 11 to 14 amplifies a difference between an ith touch sensor signal input to the inverting input terminal (−) and an (i+1)th touch sensor signal input to a non-inverting input terminal (+) and outputs ith sensor signals S1 to S4
Data Source
AI summary
A touch sensing system includes a touch screen including touch sensors and sensing lines, the touch sensors and the sensing lines being divided into first and second sensing areas, a first touch sensing integrated circuit (IC) sensing a touch input of the first sensing area using a signal received through receiving channels, a second touch sensing IC sensing a touch input of the second sensing area using a signal received through receiving channels separated from the receiving channels of the first touch sensing IC, differential amplifiers between the sensing lines and the receiving channels of the first and second touch sensing ICs, and a switch connecting a sensing line, which is closest to the first sensing area among the sensing lines of the second sensing area, to an Nth differential amplifier connected to a last receiving channel of the first touch sensing IC.