Touch Sensing Device Selective Noise Attenuation

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Solution Overview

Problem

Touch panels in mobile devices face interference issues due to noise with unspecified frequencies, leading to errors in recognizing user touches, and conventional frequency hopping can cause signal interference with other systems like WiFi, 3G/LTE, and Bluetooth.

Innovation Solution

A touch sensing device with pre-processing and attenuation units that reduce common signal noise and high-frequency components, and selectively attenuate even and odd multiple frequencies of the driving signal to improve touch recognition accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If frequency hopping is used to avoid noise interference, then touch recognition accuracy is improved, but signal interference with other systems (WiFi, 3G/LTE, Bluetooth) occurs

Engineering Contradiction:

Improvetouch recognition accuracyVSAvoidsignal interference with other systems

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent changes the frequency parameter of the driving signal from fixed to variable, implementing frequency hopping within a specific range (150-250 kHz) to avoid noise interference while maintaining compatibility with other communication systems by avoiding their frequency bands

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces dynamic frequency adjustment capability, allowing the driving signal frequency to be dynamically changed based on detected noise conditions, thereby adapting to different electromagnetic environments and avoiding interference with other systems

Inventive Principle:

Principle #15Dynamics

2Speed

If the driving signal frequency is increased to improve touch detection speed, then response time is reduced, but high-frequency noise interference increases

Engineering Contradiction:

Improvetouch detection speedVSAvoidhigh-frequency noise interference

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful high-frequency noise into a beneficial filtering opportunity by using a low-pass filter with a cut-off frequency higher than the driving signal frequency, allowing the driving signal to pass while blocking high-frequency noise components

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent optimizes the driving signal frequency to be lower than the cut-off frequency of the low-pass filter, ensuring that the signal can be detected quickly while the filter effectively removes high-frequency noise interference

Inventive Principle:

Principle #35Parameter changes

3Object-affected harmful factors

If low-pass filter is used to reduce high-frequency noise, then noise attenuation is improved, but signal delay increases

Engineering Contradiction:

Improvehigh-frequency noise attenuationVSAvoidsignal delay

Core Design Contradiction:

Object-affected harmful factorsVSLoss of time

Solution Approach 1:

The patent optimizes the cut-off frequency parameter of the low-pass filter to be higher than the driving signal frequency, allowing the signal to pass through with minimal delay while still effectively attenuating high-frequency noise components

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS9983732B2Touch sensing device capable of selectively attenuating noise and control device thereof

Publication Date: 2018.05.29 SILICON WORKS CO LTD

AI summary

A touch sensing device may include: a pre-processing unit configured to reduce common signal noise and frequency components higher than a preset cut-off frequency from a pair of signals outputted from a touch panel, in response to a driving signal; and an attenuation unit configured to attenuate a frequency of a preset frequency region in an output signal of the pre-processing unit, and output a sensing signal.