Cross-Shaped Capacitive Sensor Pattern for LCD Noise Reduction

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Solution Overview

Problem

Existing capacitive touchscreen diamond-shaped sensor patterns suffer from noise interference from LCD displays and reduced sensitivity, especially when interacting with objects having small contact surfaces like styluses.

Innovation Solution

A cross-shaped sensor pattern is introduced, where first and second electrically conductive sensor structures are coupled in perpendicular directions, forming open regions with reduced surface area and incorporating floating separators and slotted openings to enhance signal-to-noise ratio and sensitivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If diamond-shaped sensor patterns are used in capacitive touchscreens, then the sensor coverage is maintained, but noise interference from LCD displays increases and sensitivity to small contact surface objects decreases

Engineering Contradiction:

Improvesensitivity to capacitive touchesVSAvoidnoise interference from LCD display

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The sensor pattern is segmented into multiple cross-shaped sensor structures arranged in a matrix, with each cross-shaped sensor consisting of multiple arms extending in different directions. This segmentation allows for reduced sensor surface area while maintaining coverage through the distributed arm structures, thereby reducing noise interference while preserving sensitivity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The cross-shaped sensor structures feature asymmetric arm configurations where arms of different lengths extend in perpendicular directions. This asymmetric design optimizes the sensor's interaction with capacitive fields from objects of various sizes, improving sensitivity to small contact surface objects like styluses while reducing overall sensor area to minimize LCD noise.

Inventive Principle:

Principle #4Asymmetry

2Measurement precision

If diamond-shaped sensor patterns are used, then the sensor matrix coverage is maintained, but resolution and sensitivity for small contact objects are reduced

Engineering Contradiction:

Improveresolution for small contact objectsVSAvoidsensor surface area

Core Design Contradiction:

Measurement precisionVSArea of stationary object

Solution Approach 1:

Each sensor element is divided into multiple cross-shaped structures with arms extending in different directions, creating a segmented sensor matrix. This segmentation maintains comprehensive coverage through the distributed arm structures while reducing the effective surface area of individual sensors, thereby improving resolution for small contact objects.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The sensor design transitions from traditional planar diamond shapes to three-dimensional cross-shaped structures with arms extending in perpendicular directions. This dimensional change allows the sensor to capture capacitive signals from objects at different heights and orientations, improving resolution for small contact objects while maintaining compact surface area.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 cross-shaped design improves resolution, reduces noise interference, and increases sensitivity for capacitive touches and proximity detections, particularly with small contact surface objects, while maintaining a symmetric and linear touch performance.

Implementation Method 1

capacitive touchscreen panels... capacitive sensing structure... sensors... electrically conductive sensor structures... capacitive touches (or proximity detections)

Methodology Applied

Scientific EffectCapacitive sensing: Capacitance

Implementation Method 2

first electrically conductive sensor structures... second electrically conductive sensor structures... electrically coupled... signal-to-noise ratio and sensitivity

Methodology Applied

Scientific EffectElectrical field interaction: Electric Field

Data Source

PatentUS9335876B2Cross-shaped touchscreen pattern

Publication Date: 2016.05.10 STMICROELECTRONICS INT NV

AI summary

A capacitive sensing structure comprises a plurality of first sensors electrically coupled to each other in a first direction, each first sensor comprising: a first arm extending along the first direction, and a second arm extending along a second direction perpendicular to the first direction and bisecting the first arm to form open regions at least partially defined by the first and second arm; a plurality of second sensors electrically coupled to each other in the second direction, each second sensor comprising: a first arm extending along the second direction, and a second arm extending along the first direction and bisecting the first arm to form open regions at least partially defined by the first and second arm; and a plurality of single electrically conductive and electrically floating structures, each disposed within open regions of adjacent first and second sensors.