Touch Panel Noise Cancellation via Signal Difference Processing
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Solution Overview
Problem
Conventional touch panel systems are unable to reliably remove a wide variety of noises, particularly those other than impulse noise, due to inadequate noise processing configurations, which impairs detection sensitivity and increases power consumption.
Innovation Solution
A touch panel system with a plurality of sense lines and drive lines that intersect to form capacitances, featuring a subtracting section to find differences in signal values between adjacent sense lines, a decoding section to calculate capacitance distributions, and a touch detecting section to generate touch information, allowing for effective noise cancellation and reduced power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If noise processing is performed using conventional filter sections to extract AC signal components, then impulse noise can be removed, but other types of noises cannot be reliably canceled and detection sensitivity is impaired
Solution Approach 1:
The patent extracts only the necessary AC signal component from the noisy input signal using a filter section, separating it from other components including impulse noise and other types of noise. This extracted AC signal is then processed further to achieve both noise removal and maintained detection sensitivity.
Solution Approach 2:
The patent inverts the phase of the extracted AC signal by 180 degrees using a logical inversion section. This inverted signal is then added back to the original input signal, causing the AC noise components to cancel each other out while preserving the ability to detect actual touch signals.
2Object-affected harmful factors
If noise processing is performed on the entire touch panel, then comprehensive noise removal can be achieved, but power consumption increases
Solution Approach 1:
The patent applies noise processing selectively to specific regions of the touch panel rather than uniformly across the entire panel. By identifying and processing only the regions where noise is present or where touch detection is needed, the system achieves effective noise removal while minimizing power consumption in inactive regions.
Solution Approach 2:
The patent performs noise processing on a partial basis rather than comprehensively across all regions. The filter section and logical inversion section are applied selectively to AC signal components in specific areas, achieving sufficient noise removal for accurate detection without the excessive power consumption that would result from processing the entire touch panel uniformly.
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 reliably removes various noises, enhances detection sensitivity, and reduces power consumption by selectively driving and processing signals within the touch panel, thereby improving the accuracy of touch operations.
Implementation Method 1
a plurality of sense lines, and a plurality of drive lines provided so as to intersect the sense lines and form capacitances with the sense lines
Data Source
AI summary
A touch panel system includes a touch panel having sense lines, and drive lines which intersect the sense lines and form capacitance with the sense lines, a touch panel controller for processing signals of the sense lines, and a drive line driving circuit for driving the drive lines in parallel. The touch panel controller includes a subtracting section for finding differences in signals between the sense lines adjacent to each other, a decoding section for calculating a distribution of differences between the capacitances by calculating an inner product of code sequences for driving the drive lines in parallel and difference output sequences which correspond to the code sequences, a touch detecting section for obtaining touch information based on the distribution of differences between the capacitances calculated by the decoding section, and a region setting section for setting an effective region in the touch panel based on the touch information.