Touch Sensor Noise Removal via Frame Difference Binarization

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Solution Overview

Problem

Existing touch sensor technologies, particularly the frame difference method, struggle to effectively distinguish between finger boundary portions and high frequency noise, leading to incorrect detection of touch coordinates and increased manufacturing costs due to the need for a large number of transistors.

Innovation Solution

A method and device that process touch information by generating difference data from adjacent frames, binarizing it based on threshold values, filtering using a Gaussian kernel to differentiate touch boundary lines from high frequency noise, and further binarizing to remove noise, thereby correcting the light sensing data.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the frame difference method is used to detect touch coordinates, then noise components commonly present in light sensing frame data can be removed, but high frequency noise cannot be completely removed and may be misdetected as touch coordinates

Engineering Contradiction:

Improvetouch coordinate detection accuracyVSAvoidnoise removal completeness

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent segments the noise removal process into multiple stages: first removing commonly present noise through frame differencing, then separately addressing high frequency noise through additional processing. This segmentation allows each stage to target specific noise characteristics without interfering with the other, thereby achieving more complete noise removal while maintaining touch detection accuracy.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies different processing qualities to different regions of the data. By analyzing local characteristics of the light sensing data, the system applies enhanced processing specifically to regions containing high frequency noise while preserving the integrity of genuine touch signals. This local quality approach enables selective noise removal without affecting overall detection accuracy.

Inventive Principle:

Principle #3Local quality

2Measurement precision

If a touch sensor integrate circuit including a differential amplifier is used to remove high frequency noise, then high frequency noise can be removed, but a large number of transistors are necessary, increasing manufacturing cost, size, and weight

Engineering Contradiction:

Improvehigh frequency noise removalVSAvoidcircuit structure

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical/electrical differential amplifier circuit with a signal processing method implemented through computation. Instead of using physical transistors and electronic components to filter high frequency noise, the system uses digital or computational processing of the light sensing data. This substitution dramatically reduces device complexity, manufacturing cost, size, and weight while maintaining the noise removal capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent creates a computational model or representation of the noise filtering function that can be executed through software or algorithms rather than requiring physical hardware implementation. By copying the functional behavior of a differential amplifier into a computational process, the system achieves the same noise removal effect without the associated hardware complexity.

Inventive Principle:

Principle #26Copying

3Ease of operation

If the uppermost portion of a finger boundary portion is used as touch coordinates, then touch position can be determined, but it is difficult to distinguish the finger boundary portion from high frequency noise, leading to incorrect detection

Engineering Contradiction:

Improvetouch position determinationVSAvoidtouch coordinate accuracy

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent performs preliminary noise removal processing on the light sensing data before determining touch coordinates. By preprocessing the data to eliminate high frequency noise and other artifacts, the system ensures that subsequent touch coordinate determination operates on cleaned data. This preliminary action prevents misidentification of noise as finger boundary portions, thereby improving detection accuracy.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements a feedback mechanism where the results of touch detection are continuously evaluated and refined. By monitoring the detected touch coordinates and comparing them against expected patterns, the system can identify and correct false detections caused by remaining noise. This feedback loop enhances the reliability of touch coordinate determination while maintaining ease of operation.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS8330777B2Information processing method, touch information processing device, and flat panel display

Publication Date: 2012.12.11 LG DISPLAY CO LTD

AI summary

A method and a device for processing touch information and a flat panel display using the method and the device are disclosed. The touch information processing arrangement includes: generating sensor output data from a touch sensor array; computing the sensor output data corresponding to each of adjacent frames to generate difference data; first binarizing the difference data based on a predetermined first threshold value; filtering the first binarized difference data; and second binarizing the filtered difference data based on a predetermined second threshold value.